Singapore Land Group Ltd.
Clifford Centre Redevelopment
PSD Specification for Main Contract
ARP-ST-SPE-02
T1 | 18 May 2023
PIP Tender
This report takes into account the particular
instructions and requirements of our client.
It is not intended for and should not be relied
upon by any third party and no responsibility
is undertaken to any third party.
Job number
283004-00
Arup Singapore Pte Ltd
182 Cecil Street
#06-01 Frasers Tower
Singapore 069547
www.arup.com
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Singapore Land Group Ltd.
Clifford Centre Redevelopment
PSD Specification for Main Contract
Contents
Page
1
General
1.1
1.1.1
1.1.2
1.1.3
1.2
1
Project Particulars
Site Description
Project Team
Superintending Officer (SO) and Project Manager (PM)
General Description of the Works
1
1
1
2
2
2
As-built Drawings
5
3
BCA Buildability and Built Environment Transformation (BET)
Scheme
5
4
Base Specifications
6
5
Project Specific Data (PSD)
8
Appendices
Appendix A
G01-010-01 PSD for Buildable Design
Appendix B
C03-010-01 PSD for Green Concrete
Appendix C
C03-010-02 PSD for High Strength Concrete
Appendix D
C00-010 Design and Construct Performance Criteria
Appendix E
Base Specifications
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1
Clifford Centre Redevelopment
PSD Specification for Main Contract
General
This section sets out the general requirements, including scope of works, for
carrying out any works for the project and shall be read in conjunction with all
relevant work sections and other contract documents.
1.1
Project Particulars
1.1.1
Site Description
The proposed development is located at 24 Raffles Place adjacent to Collyer Quay,
bounded by Raffles Place MRT Station and high-rise buildings. Refer to Figure 1
for the site location.
The site was occupied by a 29-storey commercial office building consisting of 7
storey high retail/carpark podium and 1 storey basement which was constructed in
year 1970s. The existing foundation was a caisson type foundation.
Geylang River
Project Site
Figure 1 Site Location Plan
1.1.2
Project Team
The project team comprises the following:
Organisation
Project Manager/ Developer
Singapore Land
Architectural Design Consultant
PLP Architecture
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Clifford Centre Redevelopment
PSD Specification for Main Contract
Architect / QP
A61 Architects Pte. Ltd.
C&S Engineer
Arup Singapore Pte. Ltd.
M&E Engineer
Squire Mech Pte. Ltd.
Quantity Surveyor
AECOM Cost Consulting and Projet Management
(Singapore) Pte Ltd.
Landscape Consultant
Ortus Design Pte. Ltd.
Green Mark & ESD Consultant
GreenA Consultants Pte. Ltd
Façade & Lighting Consultant
Arup Singapore Pte. Ltd.
Acoustic Consultant
Arup Singapore Pte. Ltd.
Fire Safety Consultant
Ignesis Consultants Pte Ltd
Design for Safety Consultant
Arup Singapore Pte. Ltd.
Traffic Consultant
Ramboll
Lighting Consultant
Light Collab LLP
1.1.3
Superintending Officer (SO) and Project Manager (PM)
For this contract, Superintending Officer (SO) shall mean the Architect in their
capacity as contract administrator.
1.2
General Description of the Works
The proposed works shall include the following:
a. Construct bored piles and other foundation systems specified for the project
including withdrawing/demolishing any existing foundations or any other
inground obstructions obstructing the proposed new piles.
b. Construction of a 4 Level basement structure including excavation, temporary
support ground water and movement control, instrumentation and monitoring,
removal of all encumbrances, and other temporary works.
c. Construction of a 6 Level podium and 34 level tower super structure in
accordance with the drawings.
d. Construction of underground pedestrian link to the Raffles Place MRT station
including the required temporary support works in accordance with the
drawings.
e. Construction of all external works and drains in accordance with the drawings
and authority requirements.
f. Construction of new and modified roads and traffic junctions.
g. Construct new minor sewer pipes and minor sewer diversion, if required for
the completion of the Works.
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Clifford Centre Redevelopment
PSD Specification for Main Contract
h. Obtain all necessary approvals from the relevant authorities/agencies prior to
commencement of any works on sites, including and not limited to:
•
•
•
POWS submissions and any other required submissions to PUB due to
proximity of the works to public sewer, water mains and drainage systems.
CCTV surveys shall be carried out pre and post construction works in
accordance with PUB requirement.
Contractor shall take due care and precautionary measure to ensure that no
damage or settlement occurs to any existing sewer, water mains and
drainage systems in the course of the works. The contractor shall carry out
impact assessment to establish the influence zone of the proposed works
which affected the existing sewer, water mains and drainage systems. The
impact assessment shall be endorsed by a Professional Engineer and
submitted to PUB.
LTA MSRA & permit submissions for all works within Railway
Protection/Safety Zone.
CAAS submissions for Obstruction Control activities such as erection of
cranes or any other tall construction machineries.
i. Obtain all the cable, pipelines and any other inground services drawing from
relevant authorities/agencies/service providers to verify presence of any
inground services and utility lines within and around the development. Carry
out detection of existing underground cables and services by a Licensed Cable
Detection Worker (LCDW) and inform the relevant
authorities/agencies/service providers prior to commencement of any works.
j. Conduct condition surveys (pre and post) of buildings, services,
infrastructures, and other structures within the area of influence of the Works.
k. Engage Registered Surveyor and specialist geophysical surveyor to accurately
locate and to provide prominent physical marking on the locations of
•
•
•
•
railway protection/safety zones,
sewer and water main pipes, setbacks and corridors,
drainage reserves,
inground services.
The Registered Surveyor shall carry out topographical surveys of the
development and surrounding affected areas including level survey of all
existing surrounding drains and drainage facilities as required by PUB.
Topographical surveys shall be carried out prior to commencement of the
works and upon completion of the works.
l. The I&M contractor has been appointed by the Employer and will be novated
to the Main Contractor. The Main Contractor shall be responsible for
coordination and sequencing installation of instruments. Instruments shown in
I&M drawings are the minimum requirement. Contractor shall review and
allow provision of additional instruments as required by Contractor's QP or
Authorities. Additional I&M will be under the Contractor's own cost and time.
m. The Main Contractor shall provide steel casing for the installation of
inclinometer in wall and coordinate with I&M Contractor to install the casing
and inclinometer during secant piling works.
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PSD Specification for Main Contract
n. Design and construct ERSS system for any excavation works required for the
project. Engage Singapore Registered Professional Engineer to carry out full
design, authority submission and supervision of ERSS system and excavation
works. Provide instrumentation and monitoring works required for the
excavation works. Engage qualified site supervisors (RE/RTO) to assist the
Professional Engineer in supervising the installation of ERSS system and
excavation works.
o. Provide Professional Engineer’s Assignee(s) if required by LTA, PUB, and
any other authorities, to provide standing supervision of any critical
construction works within railway protection zones and/or sewer and drainage
corridors.
p. Coordinate and construct substructure and below ground structure such as pile
caps, underground tanks and chambers (incoming services, detention tank,
fuel tank, ICs, etc.).
q. Coordinate and construct structures of the proposed Clifford Centre
Redevelopment in accordance with the drawings.
r. The Contractor shall undertake detailed construction stage analysis to simulate
the crucial stages of the structure under construction and demonstrate
structural stability and safety. The analysis shall include for sensitivity of key
input parameters. The Contractor shall also use construction stage analysis to
simulate and demonstrate what structural compensation is required for the
superstructure to be constructed within the necessary short- and long-term
verticality tolerances. The Contractor shall develop a field monitoring plan for
checking of actual movement of the building versus predictions. The plan
shall include strain measurement of column/transfer deformation using
vibrating wire-gauge, and optical survey for lateral and vertical movement.
Measurement shall be monitored and checked throughout construction. The
plan shall also include control strategies for monitoring and checking the
performance during construction stage.
s. Construct miscellaneous structures in accordance with the drawings.
t. Engage competent and experienced waterproofing specialist to coordinate,
design and install waterproofing system to all structures in contact with
ground.
u. Construct all external works and drains in accordance with PUB, LTA and
NParks standards and codes, including road modification/enhancement works
specified in the drawings.
v. Design and provide all temporary works necessary for completing the Works.
Engage Singapore Registered Professional Engineer to carry out full design
and supervision of all temporary works.
w. The Contractor shall engage a Singapore Registered PE for the full design of
the amenity boxes located at Levels: 7th - 7th(Mid) and 18th - 19th. The design
submissions and proposals shall be endorsed by a Singapore Registered PE
and submitted for SO’s acceptance and onward submission to BCA. Authority
submissions and supervision shall be undertaken by Project QP.
x. Design and construct:
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PSD Specification for Main Contract
o All railings/barriers, catwalks, services supports, DFMA
frames/supports, façade supports, canopies, purlins, BMU support,
trellises, lift separator beams, bollards, glass support, hanging double
slabs, and any other secondary steelworks that are not shown in the
structural drawings.
o All steel connections and beam penetrations.
o The building crown including the crown signage support.
o Cable net wall supporting frames at Collyer Quay and Raffles place.
o All temporary structure including strengthening resulting from
construction sequence.
o All temporary ERSS works.
o Contractor shall check construction sequence and temporary supports
that affect load path through the transfer trusses.
The Contractor shall engage Singapore Registered Professional Engineer to
carry out full design, authority submission and supervision of these Works.
y. Liaise and coordinate with other contractor(s) appointed separately by Client.
z. Obtain authorities’ clearances for the completed works.
aa. All related works required for the completion of the above.
2
As-built Drawings
Contractor shall obtain authority approved plans in CAD from the SO. These
plans must be updated to capture all deviations or amendments, including those
captures in SO’s Instructions (SOI), Project Manager’s Instruction (PMI),
Architect’s Instructions (AI), Engineer’s Instructions (EI), Request for
Information (RFI), construction sketches, etc. Contractor is to submit such revised
plans as as-built drawings to SO for record and authority record plan submission.
The as-built plans shall be submitted progressively floor by floor not later than
two weeks from casting date. Also, the Contractor is to reflect all structural
deviations in the Final As-built models.
3
BCA Buildability and Built Environment
Transformation (BET) Scheme
The project has adopted the BCA BET scheme. The BET scheme has several
mandatory requirements that relate to the construction industry transformation
outcome requirements. The mandatory structural requirements adopted for this
project are summarized below. Refer to the Architectural specification for full
summary of the mandatory requirements applied to this project and the associated
obligations of the Contractor.
The following Structural BET requirements shall be noted and complied with:
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PSD Specification for Main Contract
•
Structural Steel floor framing shall be adopted for a minimum of 80% of
the total office area.
•
Composite columns shall be adopted for all office floors.
•
70% system formwork shall be used.
4
Base Specifications
The following sections of base specification are included in Appendix E. This
base specification shall be read in conjunction with Project Specific Data (PSD)
Specification included in Section 0 of this report.
Table 1 List of Sections of Base Specification (Appendix E)
Section
Number
Section Titles
G01-010
General Requirements Parts
C01-010
Demolition and Site Clearance
C01-020
Condition Survey
C02-010
Site Investigation
C02-020
General Earthworks (Excavation and Filling)
C02-030-01
Diaphragm Wall
C02-030-02
Sheet Pilling
C02-030-03
Contiguous Bored Pile Walls and Secant Pile Walls
C02-040-01
Jet Grouting Method
C02-050
Instrumentation and Monitoring
C03-010
Concrete Construction Generally
C03-020
Reinforcement
C03-030
Formwork and Falsework
C03-040
Designed Joints
C03-050
Water-resistance to Concrete Structures
C03-060
Precast Concrete Works
C03-070
Prestressed Concrete Works
C03-080
Concrete Repairs
C03-090-01
Ferrocement
C03-100
Sprayed Concrete
C03-110
Fibre Reinforce Concrete
C04-010
Bored Pilling
C04-020
Displacement Pilling
C04-030
Pile Testing
C05-010
Structural Steelworks
C05-020
Protective Works for Structural Steelwork
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PSD Specification for Main Contract
C06-010
Sewers Construction
C06-020
Drains Construction
C07-010
Construction of Roads and Footpaths
C07-020
Pavement for Roads and Footpaths
C07-030
Road Ancillaries
C08-010
Structural Timberwork
C08-020
Mass Engineered Timber
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5
Clifford Centre Redevelopment
PSD Specification for Main Contract
Project Specific Data (PSD)
This section specifies Project Specific Data (PSD) to be read in conjunction with
Base Specifications in Error! Reference source not found.. All modifications and
additions noted in this PSD take precedence over clauses noted in the base
specifications.
Table 2 List of PSD Specifications
Section
Number
Section Titles
Remarks
G01-010-01
PSD for Buildable Design
Appendix A
C03-010-01
PSD for Green Concrete
Appendix B
C03-010-02
PSD for High Strength Concrete
Appendix C
PSD for General Requirements Parts
Table 3
PSD for Demolition and Site Clearance
No item
PSD for Condition Survey
Table 4
C02-010
PSD for Site Investigation
No item
C02-020
PSD for General Earthworks (Excavation and Filling)
No item
C02-030-01
PSD for Diaphragm Wall
Not applicable
PSD for Sheet Pilling
Table 5
C02-030-03
PSD for Contiguous Bored Pile Walls and Secant Pile
Walls
Table 6
C02-040-01
PSD for Jet Grouting Method
Not applicable
C02-050
PSD for Instrumentation and Monitoring
Table 7
PSD for Concrete Construction Generally
Table 8
PSD for Reinforcement
Table 9
PSD for Formwork and Falsework
No item
PSD for Designed Joints
Table 10
PSD for Water-resistance to Concrete Structures
Table 11
PSD for Precast Concrete Works
Table 12
PSD for Prestressed Concrete Works
Table 13
G01-010
C01-010
C01-020
C02-030-02
C03-010
C03-020
C03-030
C03-040
C03-050
C03-060
C03-070
C03-080
PSD for Concrete Repairs
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PSD Specification for Main Contract
Table 14
C03-090-01
PSD for Ferrocement
No item
C03-100
PSD for Sprayed Concrete
No item
C03-110
PSD for Fibre Reinforce Concrete
No item
PSD for Bored Pilling
Table 15
PSD for Displacement Pilling
Not applicable
PSD for Pile Testing
Table 16
PSD for Structural Steelworks
Table 17
PSD for Protective Works for Structural Steelwork
Table 18
C06-010
PSD for Sewers Construction
No item
C06-020
PSD for Drains Construction
No item
C07-010
PSD for Construction of Roads and Footpaths
No item
C07-020
PSD for Pavement for Roads and Footpaths
No item
PSD for Road Ancillaries
Table 19
C08-010
Structural Timberwork
No item
C08-020
Mass Engineered Timber
Table 20
C04-010
C04-020
C04-030
C05-010
C05-020
C07-030
Table 3 G01-010 PSD for General Requirement Parts
Clause
Description
General
Read this section in conjunction with Project Form of Contract provision and
if there are discrepancies, the Project form of Contract takes precedence over
the requirement of this PSD section.
1.1.1 The Site
Refer to Section 1.1 of this report
1.1.2 Project
Team
Refer to Section 1.1 of this report
1.2 General
Description of
the Works
Refer to Section 1.1.3 of this report
1.3.1 Standards
and Codes
In case of conflicting requirements between the codes, refer to the Qualified
Person (QP) for resolution. Priority of precedence of different standards and
codes shall be in descending order as follows:
1. Singapore Standards SS and SS CP
2. SS ISO or ISO
3. BS or BS EN
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PSD Specification for Main Contract
4.
Other standards such as ASTM (US), AS (Australia) and DIN
(German), as agreed with the QP.
1.4.9 Approved
Subcontractors
All sub-contractors for the works are subject to the SO’s acceptance. At the
time of tender, submit the list of sub-contractors intended to be engaged for
the works. Submit with the list, details such as the relevant track records of
the firms, the qualification of the personnel and details of equipment to be
engaged for the works.
1.4.10 Site
Supervision
Provide personnel with adequate and relevant experience to SO’s
acceptance, to supervise the Work. Submit the CV of the supervisor(s) to SO
where directed.
1.4.11
Coordination of
Works
Ensure that all units, components or assemblies whether from one or
different sources, are available in time for incorporation into the Works.
1.5.2
Environment
Contractors shall submit to relevant authorities appropriate Earth Control
Measures (ECM) designed and endorsed by Qualified Erosion Control
Professionals before the start of any construction work.
1.5.4
Buildability
Refer to G01-010-01 PSD for Buildable Design.
1.6.6 Approved
Suppliers
All suppliers are subject to the SO and QP’s acceptance.
1.45
Engagement of
Bizsafe Level
Certified
Subcontractors
Refer to SO/PM/Architect/QS requirement.
1.52 Provision
of Envelopes
for Keys
During
Handover
Refer to SO/PM/Architect/QS requirement.
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PSD Specification for Main Contract
Table 4 C01-020 PSD for Condition Survey
Clause
Description
1.1.1 Prescribed
Scope of Survey
Carry out the condition survey and monitoring for all the immediate
neighbouring properties and the following specific buildings/properties
which are within the influence zone of the Works:
•
Arcade Building
•
Raffles Place MRT
•
OUE Link Bridge
•
Income @ Raffles
•
CIMB Plaza
•
Surrounding roads, drains and other infrastructure such as bus stops
and pedestrian overhead bridge
•
CCTV survey of existing sewer networks within the vicinity of the
Works.
1.4.5 Notice of
Survey
Provide at least 14 days’ notice of the intended date and scope of precondition and post-condition surveys to the affected parties.
4.4 Crack
Survey
The survey shall include at least the cracks previously identified as
described below:
CRACK SCHEDULE
Crack No. & Location
Width
Comments
N.A, to be determined after pre con survey
5.2 Survey
Records
Submit survey records as listed below within 14 days after completion of
the survey:
Item
Description
Reference
Clause(s)
Applicable
1.
Photographic Records
4.2
Yes
2.
Crack Survey Records
4.4
Yes
3.
Level Survey Records
4.5
Yes
4.
Records of Defects
4.8
Yes
5.
Plumb Survey Records
4.7
Yes
6.
Others (Insert where applicable)
5.3.3 Factual
Reporting
Unless specified otherwise, submit reports of monitoring results at weekly
interval.
5.3.4.1
Frequency
Based on the factual information received, submit interpretative reports of
monitoring results at intervals of 14 days.
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Table 5 C02-030-02 PSD for Sheet Piling / Soldier Pile Wall
Clause
Description
2.5 Permissible
Damage Criteria
for Existing
Critical
Structures or
Services
Carry out Building Damage Assessment on the effects of ground movement
to the neighbouring properties due to the works, for the purpose of
establishing suitable values for ‘Alert’ and “Work Suspension’ levels for
monitoring. Submit to SO with endorsement from a PE.
Table 6 C02-030-03 PSD for Contiguous Bored Pile Walls and Secant Bored Pile Walls
Clause
Description
1.4.1
Development of
Design
Requirement
The design of the SBP wall works is indicated in the drawings, together
with the schematic lateral supports, i.e. reinforce concrete slabs and
temporary strutting system, indicated in terms of the installation levels, the
required stiffness and preloading where necessary. Based on the
information, engage a Professional Engineer (Civil) with relevant
experience to:
•
Carry out design verification checks based on actual ground conditions
to confirm the required penetration length and size of all temporary or
permanent strutting elements and wailings for the SBP walls and
ensure that the required control on wall deflection can be achieved.
•
Prepare a response plan in the event that the temporary or permanent
strutting elements do not perform as expected in the design in
controlling the wall deflection. Ensure the response plan is feasible in
considering the construction sequence and site restraints.
•
Prepare and submit all design and construction sequence, including
drawings endorsed by the PE to the SO for review and the authorities
where applicable.
•
Propose as a response plan in the event that measures taken to control
ground movement and vibration do not perform satisfactorily.
Take into account of the design requirements as set out in Clause 2.1 below.
Submit the CV of the PE to the SO for acceptance.
1.4.4 Upholding
of Adjoining
Properties
Adequately maintain roads and footpaths within and adjacent to the site and
keep clear of mud and debris in compliance to relevant authorities’
requirements.
4.3.2.1 Deviation
of Centre Line
Maximum permitted deviation of pile centre at cut-off from specified
position shall be ±50mm in any direction.
Allow an additional 5mm for every additional metre of the cut-off level
below the top of the guide wall for hard/soft secant piles.
4.3.2.2
Verticality
For hard/soft secant piles, 1:200 for the exposed face of the pile unless
otherwise agreed.
4.3.2.3
Allowance for
Overbreak
An additional 50mm is allowed for concrete protrusions resulting from
overbreak in the ground unless otherwise agreed.
Where very soft layers or obstructions are anticipated, notify the SO to
agree on an additional tolerable allowance for the overbreak.
5.4.4 Testing of
Self-Hardening
Mixes
Check for compliance with the mix proportions.
Make cube samples at a rate of six per 50m3 of self-hardening slurry or part
in each day’s work, three for testing at 7 days and three for testing at 28
days after casting.
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PSD Specification for Main Contract
Table 7 C02-050 PSD for Instrumentation and Monitoring
Clause
Description
3.1 Schedule of
Instrumentation
Engage a qualified, competent, and suitably experienced PE to design
instrumentation and monitoring works related to his/her design of ERSS
system for excavation works. The proposed instrumentation and monitoring
works shall be submitted to the relevant authorities for approval.
4.2.2 Ground
Movements and
Vibrations
Determine permissible limit of ground movements and vibrations from
impact assessment carried out by PE. The permissible limit shall comply to
regulatory requirement and shall not exceed the following:
Building
& Road
Limits on ground movement (mm)
Horizontal
Alert
All
areas
Worksuspension
Vertical
(Settlement)
Alert
Worksuspension
To comply with LTA DBC and BCA’s
design requirement and impact
assessment acceptance criteria.
Limits on level of
vibration (mm/s)
Alert
10
Worksuspension
15 at 4 Hz
increase to
20 at 15
Hz and
above
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Table 8 C03-010 PSD for Concrete Construction Generally
Clause
Description
2.5
Execution
Class
The works are to be built in accordance with Execution Class 2, other than for
post-tensioned construction where Class 3 is to be used.
3.6.1
Designated
Concrete
When designing the concrete mix, comply with the limiting mix parameters and
constituent materials as set out below to satisfy the strength, durability and
other requirements.
The parts below shall be supplied as prescribed mixes in accordance with SS 5441 and SS EN 206-1
Requirements
Project
Project
1
Concrete designation
RC32/40
RC32/40
(ref SS544-2 Table 5)
(Piling)
2
Maximum aggregate size (mm)
20
20
Enter 10, 14, 20 or 40
3
Consistence class
S4
S3
S1, S2, S3, S4
4
Special restrictions on cement types (enter
None
None
reference if required)
5
Special requirements for aggregates (enter
Comply
Comply
reference if required)
with SS EN
with SS EN
12620
12620
6
Use of RCA permitted?
No
Yes
Maximum mass fraction of total coarse
aggregate enter a higher mass fraction of total
coarse aggregate where permitted (Ref SS 5441 cl 4.2.3c)
7
Requirements for accelerated or retarded set
None
None
8
Special colour requirements
None
None
None or see 4.11.4
9
Type and dosage of fibres
Refer to C3- Refer to C3Refer to C3-20 PSD
20
20
10 Chloride class Cl1.0 for GEN series, Cl0.20 for Cl 0.40
Cl 0.40
SRPC, Cl 0.40 for all other concretes or enter
special requirements
11 Minimum air content
None
None
12 Method of placing content
Tremie
Normal
13 Requirement for finishing concrete
None
None
14 Identity testing for consistence or other
Yes
Yes
properties required in accordance with SS EN
206-1 Annex B and SS544-1 Annex B. (If yes
then details to be added into section 6
Notes
1. All sections of the specification must be completed before it is passed to the
producer. The person sending the final specification to the producer must send
copies of the document to all other parties (PM, Engineer, Employer as
appropriate) who have contributed to the specification.
2. Where ‘None’ is entered in the table this is a default value to ensure that the
specification is complete. All those involved in completing the specification
need to check if ‘None’ is applicable
3. Guidance on specification of designed concrete can be found in SS544-1, section
4.2.
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3.6.2
Designed
Concrete
Clifford Centre Redevelopment
PSD Specification for Main Contract
When designing the concrete mix, comply with the limiting mix parameters and
constituent materials as set out below to satisfy the strength, durability and
other requirements.
The mixes below shall be supplied as designed mixes in accordance with SS544-2
and SS EN 206-1
Requirements
Project
Project
1
Concrete reference
C50/60
C60/75
(similar for
C70/85)
2
Strength class
C50/60
C60/75
3
Maximum water-cement ratio where
appropriate
4
Minimum cement content kg/m³
As per SS EN
206-1
As per SS EN
206-1
5
DC class where appropriate
6
Permitted cement types see SS 544-1 Cl
4.3.2, Note 3
As per SS5441 Cl4.3.2 note
3
As per SS5441 Cl4.3.2 note
3
7
Maximum aggregate size (mm) – Enter
10, 14, 20, 40
20
20
8
Chloride class (a value must be entered
unless Cl 0.40 is acceptable)
9
Target density/density class (for
lightweight and heavyweight concrete)
10
Consistence class S1, S2, S3, S4
S3
S3
11
Method of placing concrete
Normal
Normal
12
Requirement for finishing concrete
None
None
13
Type and dosage of fibres
Refer to C3-20
0.15% (by
volume)
polypropylene
fibrer. Refer
C03-110
14
Use of RA conforming to SS 544-2
Clause 4.3, permitted?
If YES: enter requirements for the
following in section 3.5
Not allowed
Not allowed
Maximum acid-soluble sulfate, method
for determination of the chloride
content classification with respect to
ASR, method for determination of
alkali content, any limitation on use in
concrete, e.g. exposure classes,
maximum mass fractions, etc. (Enter
details is section 3.5)
None
None
15
Special requirements for aggregates
None
None
16
Minimum air content, or other
requirements to resist freeze-thaw
attack
17
Special requirements for temperature of
fresh concrete
None
None
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PSD Specification for Main Contract
18
Special requirements for strength
developments
None
None
19
Special requirements for heat
development during hydration. See SS
EN 197-1 Cl 7.2.3 for definition of low
heat.
Low heat for
large pour
Low heat for
large pour
20
Special requirements for retarded
stiffening
None
None
21
Special requirements for resistance to
water penetration
None
None
22
Special requirements for resistance to
abrasion
None
None
23
Requirements for tensile splitting
strength
None
None
24
Additional technical requirements See
SS544-1 Clause 4.3.3 sections n & m
None
None
25
Identity additional Strength testing
required (If yes then details to be added
into section 6 of the PSD)
None
None
26
Identity additional Consistence testing
required (If yes then details to be added
into section 6 of the PSD)
None
None
27
Other properties identity testing
required (If yes then details to be added
into section 6 of the PSD)
None
None
Notes
1. All sections of the specification must be completed before it is passed to the
producer. The person sending the final specification to the producer must send
copies of the document to all other parties (SO, Engineer, Employer as
appropriate) who have contributed to the specification.
2. Where ‘None’ is entered in the table this is a default value to ensure that the
specification is complete. All those involved in completing the specification
need to check if ‘None’ is applicable
3. Guidance on specification of designed concrete can be found in SS544-1,
section 4.3.
3.6.3
Prescribed
Concrete
No prescribed concrete shall be used.
4.8.1
Concrete
Temperature
Control for
Thick
Section
The temperature of the mixed concrete for the structures shall not exceed the
specified temperatures of 30°C at the point and time of placing.
The Contractor is deemed to have allowed for the cost of installing and
monitoring the temperature monitoring devise together with all necessary
methods of controlling the temperature in his tender.
The following methods of controlling the temperature of the concrete sections
thicker than 1000mm are suggested:
1. Night concreting or restricting the mixing and placing to those periods
when the ambient temperature is below 30°C on a rising thermometer or
below 33°C on a falling thermometer.
2. Use of white or reflective paint on mixer drums, water storage tanks,
cement silos and/or storage sheds or permanent screening and shading of
the concrete mixing area.
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PSD Specification for Main Contract
3.
Shading and/or mist spraying of aggregate with water complying with
Clause 3.4 provided adjustments is made to the quantity of water added to
the mix.
4. Cooling formwork and reinforcement with water complying with C3-10
Clause 3.6 provided no pools of water remain in the forms when the
concrete is placed.
5. Using cements with a temperature of less than 60ºC at the time of adding
to the mixer.
6. Reducing the temperature of the mix water by chilling or the addition of
sliced, flaked or crushed ice provided that all the ice is melted before the
water is added to the mix.
Any formwork made of metal, concrete or other material of high thermal
capacity shall be cooled with water before the concrete is placed against it.
Concrete used for the casting of concrete sections thicker than 1000mm is to be
cooled prior to being placed. This is to be achieved by cooling the water using
finely chopped ice, shading aggregate stockpiles and cooling the aggregates. In
addition, cement with low heat development during concrete curing shall be
used (Refer to SS EN 197-1 Cl 7.2.3 for definition of low heat cement). This
shall be Portland blast furnace cement (CEM III) to SS EN 197-1 unless
otherwise directed by the Engineer.
4.8.2
Requirement
s for Curing
Concrete
Sections
Thicker than
1000mm
In addition to Clause 4.12, concrete in concrete sections thicker than 1000mm
shall be cured by the application of an approved pigmented liquid membrane.
Starter bars and construction joints shall be masked and protected from
exposure to the curing membrane. After the application of the curing
membrane, the concrete is to be properly covered with an approved Polythene
sheeting around the concrete members with the Polythene sheeting in close
contact with the concrete surfaces. The Polythene sheeting should be
adequately secured to the concrete members and fastened at the edges to
prevent draughts. On completion of the above-mentioned curing treatment to
the concrete, a layer of sand and/or polystyrene panels shall be applied onto the
exposed surfaces of the thick concrete sections as a thermal insulation. The
minimum curing period shall be at least fourteen days. Forms and exposed
concrete shall be kept continuously wet for at least the first ten days after
placing.
Contractor is to propose concrete mock-ups of the thick sections in order to
ensure that the temperature requirements are met.
4.11.1.1
Formed
Finishes
An Ordinary finish is to be provided in accordance with BS EN 13670 unless
otherwise specified in the following table.
4.11.1.5
Special
Finish
Location
Type of Finish
Refer to Architectural Specification
and Drawings.
As nominated by Architect.
Special finishes (other than formed or unformed, basic and ordinary finishes)
are required as follows:
Refer to the Architectural Specification and Drawings for location and type of
finish. Contractor shall propose a concrete mix design that is suitable for
achieving the minimum requirement.
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4.11.2.1
Unformed
Finishes
Clifford Centre Redevelopment
PSD Specification for Main Contract
A Basic finish is to be provided unless specified otherwise in the following
table.
Location
Type of Finish
No item
4.12.1
Curing
For cements with ground granulated blast furnace slag, minimum curing time is
to be 4 days.
4.13
Accuracy of
Construction
Construct to tighter accuracy to items as noted below:
Clause
No.
Description
Permitted Deviation (mm)
Elevator shaft
requirement
The contractor shall ensure the
elevator shaft (individual hoist way
and pit) is built square, plumb and
flush to within ±25mm tolerance over
the full height of the elevator shaft,
from a single reference point as per
SS550:2009 requirement. Any
protrusion (nails, etc.) shall be
removed from the elevator shaft and
any holes not required for lift
installation shall be covered.
Any areas where tighter
accuracy is required for
installation of building
services, building
envelop, architectural
finishes/fixtures, and the
like
The contractor shall coordinate with
other trade contractors or subcontractors to establish areas/elements
of structures where tighter accuracy is
required for installation of façade,
services, finishes/fixtures, and the
like. The contractor shall ensure the
structures are built in compliance with
such tighter accuracy requirement.
Structural elements in
close proximity to
development boundary
lines, green buffers,
drainage reserves, or
other statutory
demarcation and reserve
lines or setbacks
Encroachment to statutory
demarcation and reserve lines and
setbacks are not permitted.
5.1
Compliance
Testing
Testing type and quantity shall not be less than the testing requirement in the
latest edition of BCA/IES/ACES Guide Book for Site Supervision Plan.
5.4.1
Temperature
Testing of
Fresh
Concrete
All tests are to be carried out at the point of discharge into the concrete sections
thicker than 1000mm. Tests are to be carried out on samples of concrete not
less than 0.25 cubic metres that are representative of the concrete batches from
which they come.
The temperature is to be measured in the centre of the sample, or in three
evenly spaced points in the sample. The temperature shall be taken to be the
single measured temperature or the average of the three measured temperatures,
whichever is the higher.
Samples are to be tested at a frequency of not less than one sample for every 12
cubic metres of concrete placed and as directed by the Architect.
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PSD Specification for Main Contract
The results of these tests are to be immediately available to the Architect at any
time during concreting, and shall be submitted to the Architect within 3 days of
completion of any concreting.
Concrete temperature shall comply with the requirements of Clause 4.8.1 to
within an accuracy of 1ºC.
5.5
Assessment
of In0situ
Compressive
Strength
Carry out assessment of in-situ compressive strength as scheduled below:
5.6 NonDestructive
Testing
Carry out non-destructive testing to the concrete structure as scheduled below:
Element
Location
Number of tests
Refer to testing requirement specified in drawings.
Type of test
Location
Number of tests
Refer to testing requirement specified in drawings.
Table 9 C03-020 PSD for Reinforcement
Clause
Description
5.3 Material
testing
Carry out material testing in accordance with Table 1 and latest edition of
BCA/IES/ACES Guide Book for Site Supervision Plan, whichever more
stringent.
Table 10 C03-040 PSD for Designed Joints
Clause
Description
1.4.2 Provision
of Spare
Material
Provide no additional material
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PSD Specification for Main Contract
Table 11 C03-050 PSD for Water-resistance to Concrete Structure
Clause
Description
2.1.1 Durability
The waterproofing system is required to achieve a minimum design life of
30 years against leakage and any failure of waterproofing, water-tightness
or any defects.
2.1.2 Basement
Grade
The basement grade designation for various areas of the project is as
follows:
Basement Location
Usage
Grade
Below ground
tanks, pits, ICs, etc.
Lift pits
Grade 2
Fuel tanks, detention tanks,
ICs/sumps
Grade 2
Carpark
Grade 2
Plantrooms against retaining
wall at B2
Grade 3
Plantroom
Grade 2
UPL
Grade 3
Basement
Refer to Architect’s drawings and specifications for waterproofing details
for other areas (toilets, roofs, etc).
Adopt the following protection system:
Location
Protection System
Lift pits/Sumps/IC
etc.
• External bonded waterproofing membrane on
concrete base slabs and walls; and
• waterproofing admixtures on concrete base
slabs and walls.
Interface between
basement wall and
slab
•
Water stop and re-injectable grout tubes at
slab and wall interface
•
Waterproofing admixture for slab at interface
Lowest basement
slab
•
Waterproofing admixture in concrete base
slab with drainage cavity.
Basement wall
•
Skin wall with water stop and re-injectable
grout tubes at slab and wall interface
•
Water stop at skin wall construction joint
•
Waterproofing admixture for skin wall
•
Drainage cavity
•
External bonded waterproofing membrane on
concrete base slabs and walls
•
Water stops and re-injectable grout tubes at
slab/wall interfaces and construction joints.
•
Waterproofing admixture in concrete base
slab with drainage cavity
UPL wall and slab
3.4
Waterproofing
Admixtures
The waterproofing admixture shall be hydrophilic crystalline admixtures.
The waterproofing admixtures shall not affect the strength, workability,
retardation, setting time and other properties of the concrete. The trial mix
concrete shall have a corrected 30 minute water absorption of not greater
than 1.0% (one percent) as measured by BS 1881:Part 122:1983 (or except
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Clifford Centre Redevelopment
PSD Specification for Main Contract
that the age at test shall be 7 days. The trial mix concrete shall have an
average water permeability coefficient when tested at 28 days of an average
water penetration depth not greater than 10mm as measured by DIN 1048:
Part 5:1991. The admixture used must be shown by an independent
authority to have had no reduction in performance after field exposure for a
minimum of 15 years.
The contractor shall carry out absorption and permeability testing by
accredited laboratory. The SO reserves the right to take cores from the
structure to confirm compliance.
Waterproofing admixtures concrete shall be adopted/applied to the
following areas and as shown in the drawings:a. Entire concrete section of concrete elements in contact with soil/ground
water such as raft, ground slabs/beams, below ground tanks, lift pits,
etc.
b. Concrete waterproofing admixture shall extend to the sidewalls of
sumps and similar depressions of the base slab so as to form a
continuous watertight surface. The surfaces of such concrete shall be
power floated whilst the concrete is still green in accordance with the
manufacturer’s recommendations, and areas such as kickers shall be
subject to additional vibration and compaction.
c. For roof slab system
Table 12 C03-060 PSD for Precast Concrete Works
Clause
Description
1.4.1.1 Develop
the Design of
Precast Concrete
Elements
Cover the following items when developing the design:
1.4.1.3
Temporary
Supports
Item
Description
1.
Structural design of the elements in the
permanent building structure.
2.
Design for prestress covering both temporary
and permanent states.
3.
Design for demoulding stresses.
Yes
4.
Design for Lifting, handling, transporting and
storage.
Yes
5.
Design for all connections and joints.
Yes
6.
Design for waterproofing of the permanent
structure and joints.
Yes
Applicable
All temporary works including protection to precast units, temporary
supports and restraints, storage, lifting hooks/ frames etc. are to be
designed, supplied and installed by the Contractor. The Contractor is
required to submit his proposals including method statements and
supporting calculations for the approval by SO.
Lifting positions, holes and points of attachment of lifting slings to precast
units to be submitted for Engineer’s approval.
Lifting sequence shall be coordinated with the Contractor and the
Construction Manager. This should follow the construction sequence of the
superstructure as specified by the Construction Manager.
All additional reinforcements required for temporary lifting and propping
shall be designed, supplied and installed by the Contractor. No time and
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PSD Specification for Main Contract
cost will be entertained due to lifting, bracing and propping at temporary
stage.
1.4.3
Maintenance/
Replacement
Manual
Prepare and submit a maintenance/replacement manual for components and
connections as listed below:
Item
Description
Applicable
1.
Joint Sealant system
Yes
2.
Structural steel connection and fasteners
Yes
3.
Sliding joint membrane / pad
Yes
Table 13 C03-070 PSD for Prestressed Concrete Works
Clause
Description
2.1 Contractor’s
Submission and
Proposals
The design shown in the drawings are based on a notional prestressing
system. The contractor is to engage his own PE to verify and design the
final prestressing system in conjunction with the prestressing specialist and
submit to Engineer for approval.
2.1.1 Design
Intent
No items.
2.1.2
Verification on
Serviceability
In developing the design for the prestressing works, take into consideration
of serviceability requirements in the relevant codes and standards.
4.8.4.3 Bleeding
Test
Inclined tube test is required additionally.
4.8.5 Grouting
Trials
Grouting trials is required.
5.3 Tests
Testing type and quantity shall not be less than the testing requirement in
the latest edition of BCA/IES/ACES Guide Book for Site Supervision Plan.
5.3.5.1 Sampling
Duct friction test is required for the project.
Table 14 C03-080 PSD for Concrete Repairs
Clause
Description
1.4.4 Warranty
Warrant the Works for a minimum period of 5 years against all defects
from the date of completion.
2.1 Contractor
Proposal
(b) Minimum characteristic strength of the repair material shall be at least
the same as the characteristic strength of the element being repaired, but not
less than 45 MPa.
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PSD Specification for Main Contract
Table 15 C04-010 PSD for Bored Piling
γs,t
Less than 25mm
2.00
1.00
2.00
Less than 15mm
2.00
1.00
2.00
1.00
γt
1.70
1.00
2.00
1.00
γb
1.40
1.00
1.60
1.00
γs
R4
R1
R4
1.55
1.55
1.00
R1/R4
Partial Resistance Factor
R1
Tension Resistance
Compression resistance
1.35
1.55
Refer to drawing (Pile Schedule)
Refer to drawing
Model
Factor
Permitted Settlement at 2 x SWL
(mm)
Any of the piles, when under static or dynamic load test, is to satisfy the
performance criteria as set out below:
Permitted Settlement at 1.5 x SWL
(mm)
2.2 Performance
Criteria for
Serviceability
Limit State
Specified Working Load (SWL)
(kN)
Description
Pile Reference
Clause
Design Assumptions:
•
The design life of all permanent foundations is 100 years.
•
Preliminary test pile shall be carried out to verify the design parameters
prior to working piles installation.
•
All piles to be base grouted.
3.2 Drilling
Fluid
The use of support fluid is required for all piles to ensure stability of the
bore and cleanliness of the base of the pile.
3.2.1 General
Requirement
The drilling fluid shall be tested as per the specification at regular intervals
and in particular the following key construction stages:
a. When fluid is first introduced into the bore
b. Immediately upon base cleaning
c. Immediately before concreting
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4.5 Cleanliness
of Pile Bases
4.9 Grouting of
Piles
Clifford Centre Redevelopment
PSD Specification for Main Contract
The assessment of the base hardness is made using a tape measure with a
weighted end. This weight needs to be sufficiently heavy to allow a base
assessment to be made when the bore is filled with bentonite but not so
heavy that it cannot be easily moved up and down during the checking
procedure. A standard weight has been developed to meet these needs and
weighs approximately 1kg. It is made up of a short section of T25
reinforcement welded to a square section of 10mm steel plate
approximately 100mm×100mm of 20mm steel plate to form a flat base and
weighing approximately 1kg.
It is recommended that the pile be dipped in five locations; four around the
perimeter of the pile (North, South, East and West) and one in the centre. It
is important that the pile base is re-checked at the same locations to make a
reasonable assessment of any rises in the base or variations in the hardness.
The base quality is graded on a scale of 1 to 5 as described in the table
below depending on the contact made when striking the base. Grades 4 and
5 are unacceptable and the contractor is required re-clean the pile base to
remove any sludge or loose soil.
Pile base hardness grading system
Grade
Base
Quality
Observation by Arup engineer with weighted
measuring tape
1
Hard
Sharp impact
2
Firm
Sudden impact felt but some damping of impact
vibrations
3
OK
Distinct base detected with slight embedding of
weight into soil
4
Soft
Significant embedding of weight detected making
definitive base difficult to detect
5
Very Soft
Weight sinks slowly into soil making definitive
base very difficult to detect
Base grouting is required for the preliminary test pile, working load test
pile, and all building piles (except for Secant bored pile walls).
Contractor is to propose the base grouting methodology for the engineer’s
approval.
The base of grout tube/s shall be positioned 50mm above from the base of
the cage with a tolerance of +25/-0m.
Grouting shall commence a minimum of 2 days and a maximum of 8 weeks
after casting of the pile. In addition, the minimum time between cracking
the last grout tube and grouting of the first grout tube of a particular pile is
3 hours.
Cracking of the grout tube/s in preparation for the subsequent base grouting
operations shall occur between 2 days and 2 weeks after completion of pile
construction (as defined by the end of concreting).
The grouting system (pump, hoses, couplings, and grout tubes etc) shall be
capable of supplying 70 bars of pressure and both the volume and pressure
shall be read and recorded electronically in real time throughout the
grouting process.
Prior to commencing the base grouting operation, the contractor shall
demonstrate the grouting system’s compliance. The contractor shall
calibrate the delivery system by measuring the stiffness of the hoses,
couplings, and grout tubes etc. This shall be taken into account when
assessing the volume of grout injected.
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PSD Specification for Main Contract
The pile head and pile base uplift shall be measured during base grouting.
The uplift of the pile shall be measured by two independent methods during
base grouting. These shall be an LVDT (including data logging/recording)
and a dial gauge. Details of the measurement system shall be submitted
with the tender and shall be subject to the acceptance of the engineer.
The pile uplift shall also be measured at an elevation 0.5m above the pile
base using 2 retrievable extensometers installed within tubes cast into each
pile. The proposed extensometer system shall be submitted for approval by
the engineer. Fibreglass extensometers cast into the pile shall not be
accepted.
The level of the reference beam shall be checked by precise level, both
before and after the base grouting operation. The supports of the reference
beam shall be at least 3 pile diameters apart.
The following base grouting criteria shall be satisfied:
1. At completion of base grouting, the pile head uplift shall be not less
than 0.2mm and the pile base uplift not less than 0.3mm. The uplift at
the pile head or base shall not exceed 2.0mm.
2. A minimum pressure of 30 bars on each grouting tube. The residual
grout pressure of 15 bars to be held at least 2 minutes on each grout
tube.
3. A minimum grout volume of 25 litres per grout tube
Pressure measurements for criteria (2) will only be accepted if a minimum
volume of 5 litres of grout (after allowing for the compliance of the
delivery system) has been injected.
If any of these criteria is not met during the first grouting phase then the
pile shall be re-grouted, up to a limit of three grouting operations including
the initial operation. A minimum of 3 hours must be allowed between each
round of grouting.
If criteria (2) and (3) are met as a result of any secondary or tertiary
grouting and minimum uplift measurements of not less than 0.1mm at the
pile head and 0.15mm at the pile base are achieved the base grouting will
be deemed acceptable.
The grout mix shall be submitted to the engineer 14 days prior to the start
of grouting for approval, satisfying a minimum cube strength class of 25
N/mm2. Details of quality control on the grout shall include viscosity
measurement (March Cone), density measurement and cubes for strength
testing.
The quality control testing requirements for the grout are given in the table
below.
Parameter
1.
Test
Criteria
Cement Gout – Base Grouting
UCS
Three 100mm cubes
per pile, for testing, 1
at 7 days and 2 at 28
days
Nominal 25N/mm2 at
28 days
Bleed
One sample per pile
5% (max)
Specific Gravity
One sample per pile
Target (1.84) + 5%
March Cone
One sample per pile
Target (45 sec.) + 5%
Coring of the pile/grout interface shall be performed in all preliminary and
working load test piles. Coring is to extend a minimum of 1.5m below the
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toe of the pile. Unconfined compressive strength tests to be performed on
grout samples retrieved. Grout to have a UCS >1.2MPa.
5.0 Verification
and Submission
In addition to the items listed in the NPQS, the Piling Contractor shall
submit the following with their Method Statement for completion of the
works:
a. ‘Emergency recovery plan’ (detailing proposed actions in the
event of problems/ delays to pile construction, for example:
i.
Obstructions are not able to be penetrated by the piling rig
ii.
Breakdown of pile during pile construction
iii.
Concrete supply not available after completion of the bore or
if supply is interrupted during pour
iv.
Other scenarios the contractor may reasonably anticipate
b. Details of the action that would be taken to stabilise an excavation
if for any reason the completion to the excavation or the
concreting is delayed or prevented.
c. Pro-forma pile record sheet.
d. Details of installation of monitoring equipment such as
inclinometer tubes for example CV for key staff including project
manager and site engineers.
e. CV for key staff including Project manager and Site Engineers.
During the works the Contractor in addition to items detailed in the iNPQS,
shall keep records of the following:
a. Measured pile verticality of each pile
b. Site concrete testing: slump/ flow tests and cube tests: establish a
range of target values to be agreed by the engineer before the
commencement of contract piling.
Piling records shall be submitted to the SO within 24 hours of the
completion of concreting of each pile.
Table 16 C04-030 PSD for Pile Testing
Clause
Description
1.2 Related
Section
In addition to those sections listed in the Specifications document, read this
work section in conjunction with the relevant requirements of other work
sections as follows:
•
C1-20 Site Investigation
• C4-10 Bored Piling Works
C4-10 PSD Bored Piling Works
3.3.1 Equipment
for Applying
Load
Contractor shall provide reaction loads sufficient to complete the specified
load schedule, i.e. 1.2 times the maximum test load.
4.2.5
Instrumentation
for Preliminary
Piles
Piles shall be instrumented as per Test Pile Details drawing
All instrumentation shall be appropriate for the normal range of
movement/strain/vibration reasonably associated with the scheduled test
loads.
Measurements shall be taken electronically at the following times:
1. During fixing operation whilst the reinforcement cage is up in the air
2. After lowering the reinforcement cage prior to concreting
3. After concreting
4. Prior to application of the test load
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5.
4.1.1 Location of
Test Piles
During the load test
Preliminary Test Piles
•
Compression test piles shall be located within the footprint of the
building and no less than 3.5 times diameter (centre to centre spacing)
from the proposed permanent piles.
•
Each preliminary test pile shall be positioned close by to one of the Site
Investigation boreholes (within 3m).
•
Test Pile Layout Drawing indicates suggested locations for the test.
Working Load Test Piles
•
Working Load Test piles to be proposed by the contractor and agreed
with the SO.
4.2.6 Cut Off
Level
Cut Off Level shall be as per Pile Schedule Drawings.
Extend the pile shaft above ground level such that gauges and other
apparatus to be used in testing will not be damaged by water or falling
debris.
Where the pile shaft is extended above the Cut Off level of a working pile
in soil which would influence the load bearing capacity of the pile install
de-bonding.
5.1 General
Submission
In addition to the items in C4-30, the contractor shall provide the following:
•
At least 2 weeks prior to the preliminary test pile construction, the
contractor shall provide their method statement for installation of
the test pile and testing procedure to the SO for their review and
comment.
•
The Contractor shall maintain detailed soil logs (recorded by an
appropriately experienced geologist with a minimum of 5 years
relevant experience) throughout the excavation of the test piles.
These shall be submitted as per the C4-30 Section 5.2.1.
Results shall also be submitted in Excel spreadsheet format.
•
The following information shall also be presented:
•
Total load settlement plot at pile head;
•
Total load vs time plot at pile head;
•
Load vs settlement and time plot at each strain gauge level. As
reference the total load on the pile shall be recorded on the plot;
•
Difference in total and shaft load plotted against deflection.
Table 17 C05-010 PSD for Structural Steelworks
Clause
Description
1.1 Scope
Specific Requirement on Bolted Steel-Plate or Glass-Reinforced Plastic
(GRP) or Fiber-Reinforced Plastic (FRP) Tanks.
All large (2m high or more) bolted steel-plate or GRP or FRP water storage
tanks and their base structures shall be the subject of an independent firstprinciples design review from a qualified and competent Professional
Engineer (Civil).
Tanks fabrication and installation inspection and test plans shall be checked
by a qualified and competent Professional Engineer (Civil).
Materials must be verified as conforming prior to commencement of
construction. Construction inspections (including hold point inspections)
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must be undertaken by a qualified and competent Professional Engineer
(Civil). Stee material used shall comply to specification C05-010.
The record set must be reviewed by a qualified and competent Professional
Engineer (Civil) prior to filling tank with water.
1.3.1 Standards
and Codes
Alternative steel material subject to Engineer’s Approval.
1.4.1.1
Connection
Design
In the event the Steelwork Contractor submits an alternative design, the
Steelwork Contractor shall engage a PE(Civil) to develop the alternative
design based on structural design drawings, subject to SO’s and Engineer’s
acceptance.
1.4.3.1 Steel
Fabricators
Engage steel fabricators who possess suitable accreditation category as
shown in table below for the fabrication and erection works. The minimum
required grade of steel fabricator is Category S4.
Accreditation
category
Criteria of structural steel works
Category S1
1. Building, industrial plant or portal structures of over
30m in height, or
2. Large span portal, bridges or truss work of over
30m
Category S2
1. Building, industrial plant or portal structures of up
to 30m in height, or
2. Medium span portal, bridges or truss work of up to
30m
Category S3
1. Building, industrial plant or portal structures of up
to 20m in height, or
2. Short span portal, bridges or truss work of up to
20m
Category S4
Structural steel structures of up to 10m in height or
span
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1.4.6
Independent
Inspection and
Testing Agency
Clifford Centre Redevelopment
PSD Specification for Main Contract
Appointment of an Independent Inspection and Testing Agency is required
to carry out the following scope of service:
S/N
Description
Tick where
applicable
1.
Review the quality manuals, inspection & test
plans
Yes
2.
Review fabrication and erection procedures
Yes
3.
Review of welding procedure specification,
procedure qualification records, welder and
welding operator qualification records.
Yes
4.
Pre-inspection meeting and audit of fabricator
facilities/plants
Yes
5.
Review of material test certificates/records, verify
or inspect materials and witness pre-treatment
processes, if any
Yes
6.
Witness cutting/edge joint preparations, verify
joint geometry and inspect fit-up condition
Yes
7.
Verify that welding processes are carried out in
accordance with the approved welding procedures,
codes/standards and relevant documents
Yes
8.
Perform visual inspection and verify dimensional
records
Yes
9.
Select weld joints for testing & witness nondestructive testing and assess all results
Yes
10.
Witness blasting & galvanising processes
Yes
11.
Inspect painting and galvanising works
Yes
12.
Identify & verify completed structural members
and witness the handling of these members onto
lorry/truck for delivery to site
Yes
13.
Inspect delivered structural members for damage
due to handling and transportation
Yes
14.
Inspect the assembly of structural members at
erection site prior to welding
Yes
15.
Verify all welding procedure and welder
qualification records at site
Yes
16.
Witness procedure trial of stud welding process
Yes
17.
Inspect all welds & bolt tightening
Yes
18.
Select weld for testing and witness site NDT
Yes
19
Inspect all remaining site painting and witness
repairing of all protective treatment works
Yes
20.
Witness fireproofing mock-up test as well as
laboratory tests
No
21.
Witness and inspect the application of fireproofing
works
Yes
22.
Final inspection of all structural members
Yes
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23.
2.3 Execution
Class
Review all documents and records including but
not limited to the following:
- Dimensional
- Procedures
- Testing
The structure shall be constructed in accordance with execution class 3. The
following parts of the structure are to be constructed in accordance with
execution Class 4:
•
Transfer trusses at Level 6
•
King posts
4.1.2 Marking
Hard stamping shall be used in all areas.
4.3.1 Cutting
Thermal cutting is not permitted at the following areas:
•
4.3.2 Holing
N.A
Thermal holing or full size hole punching are not permitted at the following
areas:
•
5.4 Tests for
Structural Steel
Members and
Bolts
Yes
N.A
Testing type and quantity shall not be less than the testing requirement in
the latest edition of BCA/IES/ACES Guide Book for Site Supervision Plan.
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Table 18 C05-020 PSD for Protective Works for Structural Steelwork
Clause
Description
1.4.4
Independent
Inspection and
Testing Agency
Appointment of an Independent Inspection and Testing Agency is required
to carry out the following scope of service:
S/N
Description
Indicate where
applicable
1.
Review proposal for the protective system
Yes
2.
Review quality control plans
Yes
3.
Inspect the application of:
Yes
4.
•
Corrosion protection
•
Fire protection
Conduct non-destructive testing
Yes
1.4.7 Warranty
Warrant the Works (Structural Steel Framing and Protection Works for
Steel – including primary, secondary and tertiary steelwork connections,
joints and stiffeners) in accordance with contract conditions for a minimum
period of 10 years against all defects from the date of completion.
2.1.1 Durability
Account for the required durability range of High (more than 15 years) in
accordance with BS EN ISO 12944 for the protective system.
2.1.2.1
Environmental
Exposure Class
Account for the environmental exposure class for the project as follows:
Location
Member
Environmental
Exposure Class
Remarks
All internal steel
elements
All
C3
Not exposed to
weather, not near
swimming
pool/water feature
All steel elements
exposed to weather
All
C4
Note: Environmental exposure classification is categorised to six
atmospheric environmental categories and three categories for water and
soil in accordance with BS EN ISO 12944-2 Clause 5.
2.1.3.1 Period of
Fire Resistance
2.1.5
Architectural
Finishes
Account for the level of fire protection required for the various members as
follows:
Location
Member
Fire Rating
(Hour)
All
Structural
steel
As per
Architect’s
specifications
Remarks
Account for the required architectural finish effects at the various locations:
Location
Type of finish
All
architecturally
exposed steel
To Architects
specifications
Particular
requirements
(thickness etc.)
Proprietary
product specified
(if any)
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3.2.2
Prefabrication
Coating
Provision of prefabrication coating is required.
3.4 Sealants
Contractor to propose for SO’s acceptance.
3.5 Fireproofing
Materials
All fireproofing materials for steel members at various locations to be
compliant with Architect’s specifications.
3.5.1
Intumescent
Paints
Contractor to propose for SO’s acceptance.
3.5.2.3
Proprietary
Products
Contractor to propose for SO’s acceptance.
3.5.3 Dry Lining
Contractor to propose for SO’s acceptance.
5.2.1 Reference
Areas for Paint
Protection
Coating
The required number of reference areas is: 10
Note: Numbers in relation to the size of structure (painted area) are given in
BS EN ISO 12944-7.
5.3.1 Schedule
of Tests
Carry out the following tests:
Item
Description
Reference
Clause(s)
Applicable
1.
Test for Dry Film Thickness
5.3.2.2
Yes
2.
Test for Adhesion
5.3.2.3
Yes
3.
Test for Porosity/Pinholes
5.3.2.4
Yes
4.
Test for Dry Density and Thickness
5.3.4.1
No
5.
Test for Air Erosion
5.3.4.2
No
6.
Test for Deflection
5.3.4.3
No
7
Test for Compressive Strength
5.3.4.4
No
8
Test for Bond Impact
5.3.4.5
No
9
Test for Cohesion/Adhesion
5.3.4.6
No
10
Test for Contribution to Corrosion
5.3.4.7
No
11
Salt Spray Testing
5.3.4.8
No
Table 19 C07-030 PSD for Road Ancillaries
Clause
Description
1.4.3 Provide
Spare Material
Supply the following spare materials and store in an area agreed with the
SO:
Item
Quantity
Road Marking Paint
5%
Vehicle Guard Rails
5%
Retro-reflective sign sheeting
5%
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1.4.7.2 Other
Road Ancillary
Items
Clifford Centre Redevelopment
PSD Specification for Main Contract
Warrant the road marking paint and vehicle guard rails for a minimum
period as specified in LTA’s Materials and Workmanship Specification,
against all defects from the date of completion.
Table 20 C08-020 Mass Engineered Timber
Clause
Description
1.1 Scope
Further requirements for MET components in Amenity Boxes to be read as
per attachment “Amenity Boxes Performance Criteria”.
1.4.1
Contractor’s
Submissions and
Proposals
Contractor’s submissions and proposals shall be endorsed by Singapore
Registered PE and submitted for SO’s acceptance and onward submission
to BCA.
Some indicative details on the connection intention are shared as below. All
connections / fixings shall align with the required architectural intention,
e.g. concealed fixings, etc.
i)
Amenity Boxes Diagonal Truss Details
ii) Amenity Boxes Roof Connection Details
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iii) Amenity Boxes Roof (Plan View) Connection Details
iv) Amenity Boxes Roof to Corewall Connection Details
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v) Amenity Boxes Diagrid Connection Details
Reference picture:
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Appendix A
G01-010-01 PSD for Buildable
Design
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A1
Clifford Centre Redevelopment
PSD Specification for Main Contract
General
Read with the General Requirement section, and all other contract documents.
A1.1
Scope
This section covers requirements for the contractor’s design, materials and
construction methods adopted in construction works to achieve the required
Buildability Design Scores.
A1.2
Standards and References
A1.2.1
Standards
Unless otherwise agreed by the QP, ensure all of the Works comply with the
relevant requirements of the Standards and Codes listed below or referenced in the
body of the Specification. All Standards and Codes quoted are the current version
unless specific year references are noted.
Singapore Standards
Code of Practice on Buildability, 2019 Edition
A2
Buildable Design Requirement
Minimum Buildable Design Score is as follow:
•
Superstructure
90 points
•
Basement
70 points
A3
Buildable Features
A3.1
Mandatory Requirements
Materials/construction methods listed in the tables below have to be used/adopted
in construction in order to achieve the Minimum Buildable Design Scores.
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Mandatory Requirements
Basement
Superstructure
Floor mesh - in areas
80%
80%
Beam cage / Continuous stirrup - in
nos. (only accept cages from factory)
NA
NA
Column cage / Continuous stirrup - in
nos.
80%
80%
Wall mesh - in nos.
NA
NA
High strength concrete (>= Grade 70, at
least 5%)
At least 5%
NA
Self-compacting concrete (>= 30%)
At least 30%
NA
Diaphragm wall (>= 65% length of
basement permanent retaining wall)
NA
NA
Standard precast staircase of riser
height of 150mm or 175mm & tread
width of 275mm or 300mm for typical
storeys - in nos. (or alternative system
recognised and approved by BCA)
90%
90%
The contractor shall be responsible to ensure that any value engineering or
alternative design proposals comply with the Buildability Score
requirements.
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Appendix B
C03-010-01 PSD for Green
Concrete
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B1
Clifford Centre Redevelopment
PSD Specification for Main Contract
General
Read with the General Requirements section, contract preliminaries and all other
contract conditions.
B1.1
Scope
This document specifies specific requirements for green concrete which are to be
read in conjunction with C03-010 “Concrete Construction Generally”. All
modification and additions noted in this document take precedence over clauses
noted in C03-010. Clause references in this document tie with those in C03-010
with the same clause title.
B1.2
Related Sections
Read this work section in conjunction with C03-010 “Concrete Construction
Generally”. The more stringent requirement shall govern.
Refer to general notes drawing for the green cement and recycle aggregates
requirements.
B1.3
Standard and Technical Reference
B1.3.1
Standard
Unless otherwise approved by the QP, ensure all of the Works comply with the
relevant requirements of the Standards and Codes listed below or referenced in the
body of the Specification. Alternative Standards and Codes may be proposed for
approval by the QP, provided it can be demonstrated that the alternative Standards
and Codes comply with the requirements of the standards specified. All Standards
and Codes quoted are the current version, unless specific year references are
noted.
The following standards apply in addition to Section 1.3.1 of C03-010 “Concrete
Construction Generally”.
Other Standards
SS EN 12620
Specification for aggregates for concrete
PD 6682-1
Aggregates. Aggregates for concrete. Guidance on the use of BS EN 12620
BS EN 450-1 + A1
Fly ash for concrete. Definition, specifications and conformity criteria
SS EN 15167
Ground granulated blast furnace slag for use in concrete, mortar and grout
Part 1 Definitions, specifications and conformity criteria
Part 2 Conformity evaluation
In the event that the standards or codes are revised or superseded, refer to the
latest edition or the appropriate substitution for the relevant subjects.
In case of conflicting requirements between the codes, refer to the QP for
resolution, the QP’s decision shall be final.
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B1.3.2
Technical Reference
Refer to the following technical for guidance where appropriate when carrying out
the works:
a.
Sustainable Construction: A Guide on the Use of Recycled Materials
(Building & Construction Authority Singapore, 2008)
B1.4
Trade Preliminaries
Submit a list of project references in relation to experience in supply of green
concrete.
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B2
Materials
B2.1
Cement
All combined cement is to meet the requirements set out in SS 544 Part 2 Annex
A.
B2.1.1
Portland Cement
Portland Cement shall comply to Class 42.5 as specified in SS EN 197-1. Any
proposal by the Contractor to partially substitute any cementitious materials, such
as fly ash, ground granulated blast furnace slag or silica fume, for Portland cement
shall be submitted for SO’s approval. The Contractor shall not change the cement
brand or source of any approved cementitious material until he has obtained
approval in writing from the SO prior to the change.
B2.1.2
Pulverized Fuel Ash (PFA)
PFA shall conform to SS EN 197-1, Clause 5.2.4 (Fly ashes). PFA shall only be
used with ordinary Portland cement to SS EN 197-1. Mixtures of PFA with any
blended cement will not be permitted. All PFA shall come from the same single,
proprietary source.
B2.1.3
Ground Granulated Blast Furnace Slag (GGBS)
Comply with the requirements of SS EN 197-1, Clause 5.2.2 (Granulated blast
furnace slag). GGBS shall only be used with ordinary Portland cement to SS EN
197-1. Mixtures of GGBS with any blended cement will not be permitted. All
GGBS shall come from the same single, proprietary source.
B2.2
Aggregates
B2.2.1
Fine Aggregates
Comply with SS EN 12620 and not to be alkali reactive. Marine aggregates shall
not be used.
Washed copper slag (WCS) (Mohs hardness >6) shall be used to partially replace
sand as fine aggregates in concrete with the following quality control acceptance
criteria:
•
No visible foreign material like glass, metal wires, barnacles / shells etc. This
can be achieved by dry sieving through large sieve shaker to remove the larger
articles. Sieve aperture size should not be greater than 2.0 mm.
•
Water soluble chlorides shall not exceed 0.01% m/m in accordance with SS
73-17, tested weekly by third party accredited laboratories.
•
Water soluble sulphates shall not exceed 0.03% m/m in accordance with SS
73-18, tested monthly by third party accredited laboratories.
•
Recycled aggregate suppliers are accredited by BCA.
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•
Proof that copper slag recycling companies has submitted regular Toxicity
Characteristic Leaching Procedure (TCLP) to National Environment Agency
(NEA) to proof that copper slag has been processed properly. The TCLP limits
are in compliance to international recognised standard for leachate test.
•
The supplier of concrete has informed BCA on the location of batching plant
and provide records of building projects supplied with concrete using copper
slag.
•
Consent letter from SO on supplying concrete with copper slag.
B2.2.2
Coarse Aggregates
Coarse aggregate shall comply with SS EN 12620 and SS 544. Aggregates shall
not be alkali reactive. Marine aggregates shall not be used.
B2.2.3
Sampling & Testing
Sampling and testing of all aggregates shall be carried out in accordance with the
following requirements:
•
Max masonry/ lightweight material/ asphalt/ foreign material content
complying to SS 544 Part 2 Cl 4.3 Table 2.
•
Max fines content complying to BS 812-103.1.
•
Max acid-soluble sulphate (SO3) content complying to SS 73-18.
•
Max chloride content complying to SS 73-17.
•
Alkali Silica Reaction (ASR) complying to ASTM C295 and C1260.
B2.2.4
Grading
Grading tests shall be carried out in accordance with SS EN 12620 before the start
of any production and at weekly intervals when concrete is being produced. The
SP reserves the right to draw samples of aggregates from any stockpile at any time
for testing and the Contractor shall deliver the samples at his cost to any approved
accredited laboratory. Aggregates, whose grading, are found to fall outside the
approved zone shall be rejected.
B2.3
Water
Water shall be clean and free from harmful matter. If taken from a source other
than the Public Utilities Board, water shall be tested in accordance with BS EN
1008 and shall be subject to the SO’s approval.
B2.4
Admixture
To comply with the requirements of SS EN 206-1 and SS EN 934-2.
Acceptance of admixtures will only be made upon provision of satisfactory
information relating to name, type, dosage and justification for use.
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B3
Design Mix
B3.1
General
Refer to C3-10 for required strength, durability and additional requirements.
The Contractor shall submit the appropriate information as described in SS EN
206-1 and SS 544 for the SO's approval before any concrete is supplied.
B3.2
Concrete Constituents
For structural concrete, PFA content shall be not more than 55% by mass of the
specified minimum cementitious content, and GGBS content shall content shall be
not more than 85% by mass of the specified minimum cementitious content.
For structural concrete, WCS can replace up to 10% by mass of sand. For nonstructural concrete, which includes slabs on grade (non-suspended slabs),
pavements, ancillary works etc, WCS can replace up to 100% by mass of sand.
WCS for use in concrete shall be obtained from BCA approved source. WCS for
use in concrete is to be obtained from BCA approved source, which are precleared by NEA
Eco-concrete containing washed copper slag should comply with the requirement
of SS EN 206-1 and SS544, for non-structural elements in buildings or other
building elements not subject to approval of plans by BCA.
B3.3
Testing Requirement
Trial mixes of three separate batches of concrete shall be made using approved
materials and produced under full-scale production conditions. Sampling and
testing shall be in accordance with BS EN 12350 and BS EN 12390.
The workability of one trial batch shall be determined and six cubes made from
the trial. Three each shall be tested at an age of 7 and 28 days respectively. The
average cylinder strength of the cubes tested at 28 days shall exceed the specified
characteristic strength by at least 6N/mm2.
During production, the SO may require additional trial mixes to be made before a
substantial change is made in the materials or in the proportions of the materials to
be used. They need not be carried out when adjustments are made to the mix
proportions in accordance with SS EN 206-1 and SS 544.
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Requirement for Fresh Concrete
The workability of the fresh concrete shall be such that the concrete is suitable for
the conditions of handling, placing and compaction.
B5
Requirement for Hardened Concrete
The grade of concrete to be used in the Works shall be as defined by the
characteristic cylinder strength in N/mm2 at 28 days as determined from test
cubes.
The total chloride content of the concrete mix arising from the aggregate together
with that from any admixtures and any other source shall not in any circumstances
exceed the limits as specified in C3-10. When required by SO, the Contractor
shall carry out tests to demonstrate that these limits are not exceeded.
When directed by the SO, tests in accordance with BS 1881: Part 124 shall be
made on hardened concrete to determine the total sulphate content as SO3 of any
mix. The concrete shall be rejected if the sulphate content exceeds 4% by weight
of cement in the mix.
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B6
Production of Concrete
B6.1
General
Separate storage facilities with adequate provision for drainage shall be provided
for each different size of aggregates used.
Aggregates shall be handled and stored so as to minimise segregation and
contamination. All aggregate deliveries shall be inspected and the grading and silt
content of each size of aggregate from each pit, quarry or other source of supply
shall be determined at least once weekly.
The quantity of cement, the quantity of fine aggregate and the quantities of the
various sizes of coarse aggregate shall be measured by weight.
A separate weighing device shall be provided for weighing the cement.
The amount of water shall be measured, by volume or by weight. Any solid
admixtures to be added shall be measured by weight but liquid or paste
admixtures may be measured by volume or weight.
The batch weights of aggregate shall be adjusted to allow for a moisture content
typical of the aggregates being used.
The accuracy of the measuring equipment shall be within ± 3% of the quantity of
cement, water or total aggregates being measured and within ±5% of the quantity
of any admixture being used. All measuring equipment shall be maintained in a
clean, serviceable condition.
The mixing time shall be not less than that used by the manufacturer in assessing
the mixer performance.
Any adjustments of mix proportions made in order to minimise the variability of
strength and to approach more closely the target mean strength shall be subjected
to the approval of SO. Such adjustments are regarded as part of the proper control
of production but the specified limits of minimum cement content and maximum
water/cement ratio shall be maintained. Such adjustments to mix proportions shall
not be taken to imply any reduction in the target mean strength.
B6.2
Ready Mixed Concrete
Ready mixed concrete shall be carried in purpose made agitators, operating
continuously, or truck mixers. All concrete delivered to site shall be accompanied
by a delivery docket, which can be traced to the relevant individual batching
records, clearly stating the time batched, grade of concrete, specified slump,
cement content and special features such as additives used.
When truck mixed concrete is used, under no circumstances shall water be added
in transit.
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B7
Verification and Submissions
B7.1
General
All sampling and testing of fresh and of hardened concrete shall be carried out in
accordance with the relevant parts of SS78, BS EN 12350 and BS EN 12390.
The characteristic strength of concrete is the 28 days cylinder strength below
which not more than 5% of the test results may be expected to fall.
Compliance with the specified characteristic cylinder strength shall be judged by
tests made on cubes at an age of 28 days unless there is evidence, approved by
SO, that a particular testing regime is capable of predicting the strength at 28 days
of concrete tested at an earlier age.
In cases where Portland blast furnace cement or ground granulated blast furnace
slag is used as a cement substitute, compliance with the specified characteristic
strength may be judged by tests made on cubes at a later age than 28 days, where
there are suitable evidence approved by SO.
B7.2
Project Reference
Concrete suppliers shall furnish a list of project reference where concrete with
copper slag was supplied to. These suppliers must be listed in BCA’s list of Eco
Concrete Ready Mix Concrete Suppliers.
B7.3
Compliance Testing
Trial mixes of three separate batches of concrete shall be made using approved
materials and produced under full-scale production conditions. Sampling and
testing shall be in accordance with BS EN 12350 and BS EN 12390 or/and as per
requirement by BCA.
The workability of one trial batch shall be determined and six cubes made from
the trial. Three each shall be tested at an age of 7 and 28 days respectively. The
average cylinder strength of the cubes tested at 28 days shall exceed the specified
characteristic strength by at least 6N/mm2.
During production, the SO may require additional trial mixes to be made before a
substantial change is made in the materials or in the proportions of the materials to
be used. They need not be carried out when adjustments are made to the mix
proportions in accordance with SS EN 206-1 and SS 544.
Supply three copies of all test results to the SO as soon as they are available.
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Appendix C
C03-010-02 PSD for High
Strength Concrete
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General
Read with the General Requirements section, contract preliminaries and all other
contract conditions.
C1.1
Scope
This document specifies specific requirements for high strength concrete, namely
concrete with compressive strength greater than C50/60 MPa, which are to be read
in conjunction with C03-010 “Concrete Construction Generally”, as well as
“Section 3 Guide to Ensure Product Conformity and Quality for High Strength
Concrete” and “Section 4 Guideline on the Submission to BCA for the Use of
High Strength Concrete” of “BC 2 Design Guide of High Strength Concrete to
Singapore Standard CP 65”. In case of conflicting requirements, the more onerous
requirements shall take precedence. Clause references in this document tie with
those in Section 4a with the same clause title.
C1.2
Related Sections
Read this work section in conjunction with C03-010 “Concrete Construction
Generally”.
C1.3
Standard and Technical Reference
C1.3.1
Standard
Unless otherwise approved by the QP, ensure all of the Works comply with the
relevant requirements of the Standards and Codes listed below or referenced in the
body of the Specification. Alternative Standards and Codes may be proposed for
approval by the QP, provided it can be demonstrated that the alternative Standards
and Codes comply with the requirements of the standards specified. All Standards
and Codes quoted are the current version, unless specific year references are
noted.
The following standards apply in addition to Section 1.3.1 of C3-10 “Concrete
Construction Generally”.
Other Standards
BC 2
Design Guide of High Strength Concrete to Singapore Standard CP 65
In the event that the standards or codes are revised or superseded, refer to the
latest edition or the appropriate substitution for the relevant subjects.
In case of conflicting requirements between the codes, refer to the QP for
resolution, the QP’s decision shall be final.
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C1.4
Trade Preliminaries
C1.4.1
Mix Design
Engage qualified and experienced personnel to prepare and submit concrete mix
design for approval by the SO.
C1.4.2
Quality Management System
Work to a Quality Management System consistent with SS ISO 9001. Provide
details to the SO prior to commencement of work on site.
C1.4.3
Construction Joints
Engage qualified and experienced personnel to prepare and submit suitable
construction joints and details for approval by the SO, including joints where
different grades of concrete meet.
C1.4.4
Project Reference
Submit a list of project references in relation to experience in supply of high
strength concrete, including historical data if available.
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C2
Performance Requirements
C2.1
Concrete Mix and Concreting Process
Ensure the concrete mix delivered and the concreting process will achieve the
specified concrete quality uniformly and consistently for all the concrete
members, taking into consideration of site conditions and reinforcement details.
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Materials
All Clauses shall make reference to C03-010 “Concrete Construction Generally”.
C3.1
Concrete
Concrete shall conform to SS 544-2 and SS EN 206-1.
C3.2
Cement
High early strength cement should be avoided.
C3.3
Fine Aggregates
Comply with SS EN 12620 and not to be alkali reactive.
C3.4
Coarse Aggregates
Comply with SS EN 12620.
C3.4.1
Size
Not to exceed 20mm.
Not too angular and elongated.
C3.5
Recycled Aggregate and Recycled Concrete
Aggregate
Refer to C03-010.
C3.6
Water
Refer to C03-010.
C3.7
Admixtures
To comply with the requirements of SS EN 206-1 and SS EN 934-2.
Acceptance of admixtures will only be made upon provision of satisfactory
information relating to name, type, dosage and justification for use.
Superplasticisers should be used to achieve maximum water reduction.
Considerations should be made to retain reasonable workability during
transportation and placing.
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C3.8
Concrete Mix Constituents
C3.8.1
Concrete Mixes
C3.8.1.1 Design Mixes
Cement content would usually be optimum at 450-550 kg/m³. Target
water/cement ratio can be in the range of 0.30-0.35, or even lower. The mix
should be cohesive with minimum voids. This can be done by theoretical
calculations or subjective laboratory trials. Higher workability should be specified
to avoid honeycombing.
The design mix can achieve a higher ultimate strength with a low initial strength
gain and cementitious additions and micro-cracking associated with high thermal
gradient can be avoided. Strength compliance shall be measured at 56 days instead
of 28 days.
Maximum temperatures and thermal gradients and their effect on constructability
and long term design properties, should be determined during preconstruction
trial, including effect of curing on strength development.
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Workmanship
All Clauses shall make reference to C03-010 “Concrete Construction Generally”.
C4.1
Construction Joints
Propose method of pouring HSC at joints where different grades of concrete meet.
C4.2
Formed Finishes
All formed finishes for columns to be of the standard mentioned below unless
otherwise specified. Use high quality concrete and formwork. Thoroughly
compact the concrete. All surfaces to be true, with clean arises. Only very minor
surface blemishes may occur, with no staining or discolouration from the release
agent.
Prepare a sample of the specified formed finishes at the start of the Contract to the
approval of the SO, to be kept and used as a reference throughout the duration of
the Contract.
C4.3
Accuracy of Construction
Construct all work with high strength concrete within half the permissible
deviations given in C03-010 “Concrete Construction Generally”.
Note that the tolerances given here are not cumulative. Carry out regular checks
on the accuracy of the structure and if a part of the structure is found to be out of
tolerance propose any remedial work required.
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C5
Verifications and Submissions
C5.1
Compliance Testing
All Clauses shall make reference to C03-010 “Concrete Construction Generally”.
C5.1.1
Testing of Concrete Cubes
Two additional set of samples shall be retained for cube test at 56 and 90 days,
respectively, on top of the numbers specified in SS EN 206-1 and SS 544.
C5.1.2
Non-Destructive Testing
Carry out non-destructive testing in accordance with the relevant parts of SS78 on
all actual structural elements made up with high strength concrete (hammer tests
or ultrasonic pulse velocity measurements) for comparison with compliance cube
test results. This is to establish that no significant difference exists between the
two sets of results. Minimum 5 sets to be conducted on each element subject to
correlation requirement.
C5.2
Submission
C5.2.1
Mix Proportion
To submit materials and proportions that are evaluated in the laboratory to
determine the appropriate material proportions and their relative characteristics up
to full strength being achieved. To include production sized trials which will
establish optimum batching and mixing sequence.
For truck mixing, maximum load that can be mixed adequately should be
determined.
C5.2.2
Concrete Properties
Fresh concrete shall be tested for (but not limited to):
a) Slump
b) Air content
c) Temperature
d) Slump loss
Hardened concrete shall be tested for (but not limited to):
a) Compressive strength
b) Modulus of elasticity
c) Modulus of rupture
d) Shrinkage
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e) Creep
Tests for hardened concrete shall be based on standard cured specimens and on
cores drilled from monolith mock-up of adequate size and the results to be
correlated based on adequate sampling.
C5.2.3
Non-compliance
To submit procedures to deal with non-compliance of design strength of HSC.
C5.2.4
Concrete Suppliers
To submit details of qualified concrete supplier including:
a) Successful production-sized trials
b) Successful full scale trial casting of typical structural sub-assemblage
c) Plans to measure development of strength and temperature
d) Project references
e) Historical data on production of similar concrete strength.
f) Quality Management System, including Quality Assurance and Quality
Control plans.
g) Capabilities and qualifications of experienced personnel
h) Testing and batching facilities
i) Accreditation of test laboratory
C5.2.5
Method Statement
To submit the following for SO’s approval:
a) Batching of concrete in plant
b) Delivery of concrete up to before placement
c) Placement of concrete, including during wet and hot climate
d) Curing of concrete
e) Test programmes
f) Solutions to non-compliance test results
C5.2.6
Authority Submission
To assist SO by providing relevant documentation for submission and obtaining
approval from authority on the use of high strength concrete. This includes:
1.
to provide a Quality Control and Assurance Manual:
a)
Concrete mix design
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b)
The concrete supplier should carried out laboratory trial mixes on the
proposed concrete mixed design to show that they are achieved the
required target mean concrete strength and standard deviation with
local available materials, subjected to QP’s acceptance.
c)
The supplier should carry out plant trial for different batches of
concrete and subject the concrete for tests for the required concrete
properties at different ages and provide the statistical analysis of test
results.
d)
Quality Control Procedures at the plant
2.
to provide a concrete specialist to review the Quality Control and Assurance
Manual above and report on its suitability.
3.
to propose a full-scale mock up and the required concrete strength and
properties and quality control procedures at site such as measuring of
temperature, slump tests, etc.
4.
to consolidate all information into High Strength Concrete Report to BCA
BC2 requirement.
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Appendix D
C00-010 Design and Construct
Performance Criteria
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General
Read with the General Requirements section, contract preliminaries and all other contract
conditions.
The Contractor shall be fully responsible for the complete design of all works identified as
Design and Build. The Contractor shall develop the civil and structural design in accordance
with the Employee’s requirements as stated in the contract document.
It is the duty of Contractor to ensure that the proposed design is in alignment with the design
intent of the architect.
The Contractor shall be responsible to carry out verification on the accuracy, adequacy and
correctness of the design and build information provided in the contract document. It is to be
at the risk of the Contractor to rely on that information and there shall be no additional time
and cost implication to the contract due to the information provided.
The Contractor shall be informed and deemed to have accepted that the design and information
for design and build scope shown in the contract document is the minimum requirements (but
not exhaustive) and shall be subjected to any further requirements imposed by the relevant
authorities.
The Contractor shall adopt and accept all the design for the design and build scope shown in
the contract document as if it is their own design. The Contractor shall be deemed to undertake
full design responsibility and liability of the works. The Contractor shall be responsible for any
deficiencies or discrepancies of the design. In the case of difference between the minimum
requirements and further requirements by the relevant authorities, the more stringent
requirement shall govern.
The design and build scope shown on structural layouts illustrates indicative member sizes and
structural systems and are generally for the Contractor’s information only.
D1.1
Design Responsibility
Contractor shall engage and appoint a Qualified Person who is a Singapore registered
Professional Engineer to carry out full detailed design and documentation including statutory
submissions to obtain all necessary clearances/approvals from all relevant authorities.
Contractor’s appointed Qualified Person/Professional Engineer shall engage and appoint the
required qualified site supervision team to supervise the construction works in accordance with
building control acts and regulations.
The Contractor shall be responsible for ensuring full compliance with the latest edition of the
relevant building regulations, standards and codes of practices, and by-laws of Republic of
Singapore.
D1.2
Alternative Structural System Proposals
The Contractor is allowed to propose any alternative structural systems with the following
requirement taken into account:•
To conform with the Employer’s requirements and the contract documents.
•
To conform with the appropriate standards, codes of practices, statutory requirements
and particular requirements as specified in the contract document.
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•
To be coordinated with the requirements of architectural, mechanical, electrical and
other related disciplines/specialist.
•
To achieve maximum operational, functional and maintenance efficiency.
•
To achieve maximum buildability, sustainability, standardization and optimization of
construction speed.
D1.3
Reference Documents
The following reference document are provided as part of tender/contract document:
•
•
•
•
Soil Investigation reports
Wind Tunnel Test Report
Architectural Drawings
Structural Specification
These reference documents are provided for information. The contractor and its designer
shall review and carry out the necessary verifications and/or additional
tests/surveys/analysis/assessments, which are deemed to be part of the Works, to satisfy
himself and the approving authorities on the accuracy and completeness of information
provided.
D2
Scope of Works
The scope of works shall include all scope necessary for the completion of design, statutory
approval, and construction of the following elements:
•
All railings/barriers, catwalks, services supports, DFMA frames/supports, façade
supports, canopies, purlins, BMU support, trellises, lift separator beams, bollards,
glass support, hanging double slabs, and any other secondary steelworks that are not
shown in the structural drawings.
•
All structural steel connections and beam penetrations.
•
The building crown including the crown signage support.
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Figure 2 - Crown D&B Scope Definition
Figure 3 - Crown Signage Indicative Size and Location
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Cable net wall supporting frames at Collyer Quay and Raffles place.
Figure 4 - Cable Net Notional Structural Scheme to Illustrate Scope of Work, similar at Collyer Quay
•
All temporary structure including strengthening resulting from construction sequence.
•
All temporary ERSS works.
•
Contractor shall check construction sequence and temporary supports that affect load
path through the transfer trusses.
The scope of works shall include all scope necessary for the completion of design, and
construction of the following elements:
•
D3
The amenity boxes located at Levels: 7th - 7th (Mid) and 18th - 19th. (Note - BCA
submission and construction supervision to be undertaken by project QP)
General Design Requirements
The following sections present the requirements for the design of all structures.
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Design Guidelines
The system and components shall be designed in accordance with the following standards
and guidelines. In case of discrepancies between the standards the SO shall be contacted for
further clarification.
•
SS EN 1990 + NA
Eurocode 0: Basis of Structural Design
•
SS EN 1991 + NA
Eurocode 1: Actions on Structures
•
SS EN 1992 + NA
Eurocode 2: Design of Concrete Structures
•
SS EN 1993 + NA
Eurocode 3: Design of Steel Structures
• SS EN 1994 + NA
Eurocode 4: Design of Composite Steel and Concrete
Structures
• SS EN 1995 + NA
Eurocode 5: Design of Timber Structures
•
Eurocode 7: Geotechnical Design
SS EN 1997 + NA
• SS EN 1998 + NA
Eurocode 8: Design of Structures for Earthquake Resistance
• BCA BC1:2012
Design Guide on Use of Alternative Structural Steel to BS 5950
and Eurocode 3
• BCA BC3:2013
Guidebook for Design of Buildings in Singapore to
Requirements in SS EN 1998-1
•
Building and Construction Authority Approved Document Acceptable Solutions
•
Land Transport Authority Code of Practice for Railway Protection
•
Land Transport Authority Civil Design Criteria for Road and Rail Transit Systems
•
Public Utility Board Code of Practice on Surface Water Drainage
•
Public Utility Board Code of Practice on Sewerage and Sanitary Works
•
Fire Code 2013
Any other relevant current Singapore Standards and codes of practice and/or guidelines
issued by relevant authorities.
This document shall be read in conjunction with the relevant requirements of the following
specification sections:
•
C03 Concrete Construction Work
•
C05 Structural Steel Work
•
C08-010 Structural Timber Works
•
C08-20 Mass Engineered Timber
D3.2
Design Life
In accordance with Table NA.2.1 in the Singapore National Annex to SS EN 1990: Basis of
Structural Design, the proposed structures are classified as working life category 4 and
therefore be designed to achieve a durability and service life, with appropriate maintenance of
50 years.
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Table: Design Working Life Table NA2.1 from SS NA EN 1990.
D3.3
Durability & Fire
General requirements for durability are as set out in SS EN 1990.
D3.3.1
Concrete Exposure Classification
The exposure classes are as defined in Table 4.1 of SS EN 1992-1-1 and Table A.1 of SS
544-1:2019. The values of minimum concrete cover to reinforcement are in accordance with
Table A.4 of SS 544-1:2019. (SS 544-1:2019 is Singapore’s adoption of BS 8500-1: 2006.).
D3.3.2
Structural Steel Corrosion Protection
Corrosion protection of structural steel shall comply with EN ISO 12944. Cross reference
shall be made to the requirements of C05-020 and the corresponding PSD.
D3.3.3
Fire Rating
Structural members shall be designed to comply to fire rating requirements specified in Code
of Practice for Fire Precautions in Building: 2013 by Singapore Civil Defence Force and SS
EN 1992-1-2.
Fire resistance periods as follows, unless noted otherwise on fire plan by architect:
• Substructure – 4 Hours
• Superstructure – 2 Hours
Structural steel elements shall be fire protected using applied fire protection coatings.
Connections of steel elements shall also be fire rated to the most onerous rating of the two
connecting elements. The fireproofing system shall be approved by the Architect.
Contractor shall engage a fire engineer / specialists to ensure the structural members can
perform under fire load as per code and authority requirements.
Fire resistance for reinforced concrete elements shall be achieved by adequate cover to the
reinforcement based on the requirements of the design standard.
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D3.4
Materials
D3.4.1
Concrete
Concrete shall be specified and produced in accordance with SS EN 206-1.
The concrete mix designs shall achieve the durability requirements for the required exposure
classes in Table A.4 of SS 544-1:2019 and DC-class based on ACEC-class determined in
accordance with Table A.10 and A.12 of SS 544-1:2019.
D3.4.2
Steel Reinforcement
The properties of steel reinforcement to be used in the design shall comply with BS 4449
(steel for the reinforcement of concrete) and BS4483 (steel fabric for the reinforcement of
concrete). This British Standard compliments SS EN 1992-1-1, Annex C. All reinforcing
shall be Class B.
D3.4.3
Prestressing Strand
Prestressing strands shall be manufactured in compliance with BS 5896 Specification for
High Tensile Steel Wire and Strand for the Prestressing of Concrete.
D3.4.4
Structural Timber
All timber members shall be specified and produced in accordance with SS EN 1995.
The Contractor is responsible for the design of member sizes and connection details of those
elements shown on the drawings, the same elements shall be regarded as indicative only and
the Contractor shall be responsible for ensuring that the comply to SS EN 1995.
Contractor shall if necessary, engage a fire engineer / specialists to ensure that the structural
members can perform under fire load as per code and authority requirements.
D3.4.5
Structural Steelwork
All structural steelworks shall be designed as Class 1 to BC1 manufactured and tested in
accordance with the following standards:
•
BS EN 10025
Hot rolled products of structural steel
•
BS EN 10210
Hot finished structural hollow sections of non-alloy and fine grain steels
•
BS EN 10219
Cold formed welded structural hollow sections of non-alloy and fine grain
steels
D4
Loading and Stability
Reference shall be made to the loading plans, codes of practice and reference documents. In
case of discrepancies between the reference documents the SO shall be contacted for further
clarification.
D4.1
Load Combinations
Load combinations shall be considered as per Section D3.1.
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D4.2
Clifford Centre Redevelopment
PSD Specification for Main Contract
Dead Load
Dead and superimposed dead loads shall be considered as per Section D3.1. Reference shall
also be made to the loading plans. The more stringent requirement shall govern.
Density of construction material shall be in accordance with Annex A of SS EN 1991-1-1.
Concrete (reinforced, normal weight)
25.0 kN/m3 including normal percentage
of reinforcing and prestressing steel
Concrete (plain, normal weight)
24.0 kN/m3
Structural steel
78.5 kN/m3
Water
10.0 kN/m3
Planter soil
20.0 kN/m3
Glass
25.0 kN/m3
Brick/concrete block
22.0 kN/m3
D4.3
Live Load
Live and stability loads shall be considered as per Section D3.1. Reference shall also be made
to the loading plans. The more stringent requirement shall govern.
D4.4
Wind
The wind load shall be determined based on the code of practice and findings of the Wind
Tunnel Test Report. The more stringent requirement shall govern. Wind actions shall be
determined in accordance with SS EN 1991-4:2010 and Singapore national annex SS EN
1991-1-4 using a basic wind velocity (Vb,0) of 20m/s as recommended in the Singapore NA.
D4.5
Thermal Loading
In accordance with NA to SS EN 1991-1-5 the 50-year return period maximum and minimum
shade temperatures are 35.7ºC and 19.5ºC respectively. A thermal range of +/-10ºC shall be
used in the design.
D4.6
Lateral Deflection Criteria
The total lateral deflection at the top of the building under the characteristic serviceability
loading combinations shall be limited to H/500, where H is the total height of the building.
The relative lateral deflection over any one storey under the characteristic serviceability
combinations shall be limited to h/500, where h is the height of the storey.
Lateral deflection of earth retaining wall shall be limited to 0.5% of the excavation depth in
accordance with BCA Advisory Note 1/09. Wall deflection and ground movements shall be
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checked with consideration of adjacent buildings and foundations in accordance with BCA
circular on impact assessment to adjacent structures from ERSS works.
D4.7
Vertical Deflection Criteria
The following vertical deflection criteria for slab and beams shall be adopted in the design:
Construction dead loads
Span/200 (max 25mm)
Service Imposed Loads
Cantilevers
Length/180
Floor Beams
Span/360
Beams carrying brittle finishes.
Span/500
Span/200 (max 30mm)
Total Loads
Where deflections exceed 30mm pre-cambering shall be implemented to offset the deflection.
D4.8
Vibration
Analysis of vibration response shall follow an established and reputable method. Analysis
modelling for the purpose of prediction of vibration performance shall be undertaken using a
3D model in a reputable software platform. The following limits shall be applied:
•
Amenity boxes shall be designed to response factor limit of 4.
•
All members shall achieve a minimum frequency of 4 Hz
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PSD Specification for Main Contract
Appendix E
Base Specifications
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(1) G01-010 GENERAL REQUIREMENTS PARTS
(2) C01-010 Demolition and Site Clearance
(3) C01-020 Condition Survey
(4) C02-010 Site Investigation
(5) C02-020 General Earthworks (Excavation and Filling)
(6) C02-030-01 Diaphragm Wall
(7) C02-030-02 Sheet Pilling
(8) C02-030-03 Contiguous Bored Pile Walls and Secant Pile Walls
(9) C02-040-01 Jet Grouting Method
(10)C02-050 Instrumentation and Monitoring
(11)C03-010 Concrete Construction Generally
(12)C03-020 Reinforcement
(13)C03-030 Formwork and Falsework
(14)C03-040 Designed Joints
(15)C03-050 Water-resistance to Concrete Structures
(16)C03-060 Precast Concrete Works
(17)C03-070 Prestressed Concrete Works
(18)C03-080 Concrete Repairs
(19)C03-090-01 Ferrocement
(20)C03-100 Sprayed Concrete
(21)C03-110 Fibre Reinforce Concrete
(22)C04-010 Bored Pilling
(23)C04-020 Displacement Pilling
(24)C04-030 Pile Testing
(25)C05-010 Structural Steelworks
(26)C05-020 Protective Works for Structural Steelwork
(27)C06-010 Sewers Construction
(28)C06-020 Drains Construction
(29)C07-010 Construction of Roads and Footpaths
(30)C07-020 Pavement for Roads and Footpaths
(31)C07-030 Road Ancillaries
(32)C08-010 Structural Timberwork
(33)C08-020 Mass Engineered Timber
3
108
134
143
187
238
265
283
297
316
361
397
414
428
442
458
500
536
559
576
601
615
654
687
750
791
815
842
863
885
912
930
955
979
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(1) G01-010 GENERAL REQUIREMENTS PARTS
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1
GENERAL
This Section sets out the general requirements for carrying out any works for the Project and shall be
read in conjunction with all relevant work Sections and other contract documents.
In addition, under the same clause heading of each Section, any modifications and additions as listed in
the Project Specific Data (PSD) shall take precedence over the original specification appended under
same clause.
1.1
Project Particulars
1.1.1
The Site
The Site is located at [to be specified by user].
1.1.2
Project Team
The following words shall have the meaning assigned to them:
1.1.3
.
Organisation
Address
Represented by
Architect
[to be specified by
user]
[to be specified by
user]
[to be specified by user]
C&S Engineer
[to be specified by
user]
[to be specified by
user]
[to be specified by user]
M&E Engineer
[to be specified by
user]
[to be specified by
user]
[to be specified by user]
Quantity Surveyor
[to be specified by
user]
[to be specified by
user]
[to be specified by user]
Definitions, Abbreviations and Interpretations
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1.1.3.1
Definitions
In the Specification, the following words and expressions shall have the meanings hereby assigned to
them except where the context otherwise requires:
"Employer" shall mean the party as set out in the Conditions of Contract.
"Consultants" shall mean the Employers Appointed Architectural Consultant, Civil and Structural
Engineering Consultant, Mechanical and Electrical Engineering Consultant, Quantity Surveying
Consultant, Project Management Consultant and other appointed Consultants.
"SO" shall mean the Superintending Officer who is the Architect, the Engineer or their representative on
site, or as designated by the Employer.
"Architect" shall mean the Employers Appointed Architectural Consultants who is registered with the
Board of Architects in Singapore.
"QP" shall mean Qualified Person who is a registered architect or a professional engineer with valid
practical certificate registered in Singapore.
"PE" shall mean Professional Engineer who is registered under the Professional Engineers Board,
Singapore
"AE" shall mean Authorised Examiner who is approved by the Commissioner for Workplace Safety and
Health of the Ministry of Manpower by a Certificate in writing for the purpose of carrying out
examinations and tests on lifting equipment in accordance with the Workplace Safety & Health
(General Provisions) Regulations.
"Contractor" shall mean the party as set out in the Conditions of Contract.
"Registered Surveyor" shall mean Surveyor who is registered under the Land Surveyor Board,
Singapore
"as approved" shall mean as approved by the Superintending Officer in written format. "as
agreed" shall mean as agreed with the Superintending Officer.
"as directed" shall mean as directed by the Superintending Officer. "or
other" shall mean as approved by the Superintending Officer
"as required" or "as shown" or "as indicated" or "as specified" shall mean as required or as shown or as
indicated or as specified in the Drawings and/or Specification.
"acceptance" and "approval" are used within the following limitations:
1.1.3.2
(a)
No approval or acceptance by the SO shall relieve the Contractor of any responsibility to achieve the
specified quality and performance of the work under the Contract.
(b)
Any approval given in respect to samples of materials, workmanship or methods of construction
submitted in accordance with the requirements of the Specification, are not to be interpreted as denoting
any degree of satisfaction with the materials used in the Works or in the execution of the Works.
Abbreviations
The following abbreviations are used in the Specification: ABGSM
= Association of British Generating Set Manufacturers
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AC or ac = alternating current
ACMV = Air-Conditioning and Mechanical Ventilation AISI =
American Iron and Steel Institute
AMCA = Air Movement and Control Association
ANSI = American National Standard Institute AS
= Australian Standard
ASTM = American Society for Testing and Material AVA
= Agri-Food and Veterinary Authority of Singapore BCA =
Building and Construction Authority
BMT = Building Maintenance Team BS
= British Standard
CAAS = Civil Aviation Authority of Singapore CCTV
= Closed-circuit Television
CPF = Central Provident Fund Board
CP = Code of Practice
DC or dc = direct current
DIN = Deutsches Industrie Normen
DSTA = Defence Science and Technology Agency (DSTA) ECM =
Earth Control Measures
ECO = Environmental Control Officer
EIA = Electronic Industry Association
ELCB = Earth Leakage Circuit Breaker
EMA = Energy Market Authority
EN = European Standards
EPR = Ethylene Propylene Rubber
FTRR & I = for their respective rights and interests FSSD =
Fire Safety and Shelter Department
GS or gs = Galvanised Steel GST
= Goods and Services Tax HRC =
High Rupturing Capacity
IDA = Info-Communications Development Authority of Singapore IEC =
International Electrotechnical Commission
IECEE = IEC System for Conformity Testing and Certification of Electrical Equipment
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IP = Index of Protection
ISO = International Organization for Standardization ITE
= Institute of Technical Education
JIS = Japanese Industrial Standard LEW
= Licensed Electrical Worker MCB =
Miniature Circuit Breaker MCCB =
Moulded Case Circuit Breaker
MEWR = Ministry of the Environment and Water Resources MSSL
= Market Support Services Licensee
Max or max = maximum
Min or min = minimum
MOM = Ministry of Manpower
MRT = Mass Rapid Transit MS
or ms = mild steel
NEA = National Environment Agency
No. or no. = number
ONORM = Osterreichisches Normungsinstitut (Austrian Standard) PBTS
= Public Basic Telecommunications Service Operators
PLS = Product Listing Scheme
PowerGrid or Grid = PowerGrid Ltd PPE
= Personal Protection Equipment PSB =
TUV SUD PSB Pte Ltd
PSD = Project Specific Data
PTL = Public Telecommunication Licensees PUB =
Public Utilities Board
PVC or pvc = Polyvinylchloride RC
or rc = Reinforced Concrete
RCCB = Residual Current Circuit Breaker rms =
root mean square
SAC = Singapore Accreditation Council
SCV = StarHub Cable Vision Pte Ltd
SINGLAS = Singapore Laboratory Accreditation Scheme SLA =
Singapore Land Authority
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SMRT = Singapore MRT Ltd SOA
= Socket-outlet assembly SPPG =
SP Power Grid
SPSL = SP Services Ltd SS
= Singapore Standard SWA
= Steel wire armoured
SWG = Standard Wire Gauge (British) SingTel
= Singapore Telecommunications Ltd
TIA = Telecommunications Industry Association UHF
= Ultra High Frequency
UL = Underwriters Laboratories Inc
uPVC or UPVC = Unplasticised Polyvinylchloride VHF =
Very High Frequency
v/v = measured by volume
w/w = measured by weight
WSH = Workplace Safety and Health
WSHO = Workplace Safety and Health Officer
XLPE = Cross linked polyethylene
% = percent
± = plus or minus
= or < = less than or equal to
= or > = greater than or equal to
< = is less than
> = is greater than
1.1.3.3
Interpretations
(a)
Words importing the singular shall also include the plural and vice versa where the context requires.
(b)
The clause or subclause headings in the Specification shall not be deemed to be part thereof or be taken
into consideration in the interpretation or construction thereof or of the Contract.
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1.1.4
(c)
All clauses, including all subclauses under them in the Specification shall be deemed to be directed at the
Contractor unless expressly specified otherwise to the contrary, and the Contractor shall perform and/or
comply with such instructions, directions, requirements and obligations specified in the Specification and
required under the Contract.
(d)
All Acts of Parliament, statutes, regulations, bylaws, orders, local and foreign standards and codes of
practice specified shall be deemed to refer to the latest and shall be deemed to include any
amendments, and/or modifications and/or additions and/or re- enactments thereto.
BCA Green Mark
The Project shall attain the respective Green Mark Score (as per BCAs requirements) to achieve the
stipulated Green Mark rating.
Allow for all cost and manpower in relation to application, submission and assessment in order to
receive the Green Mark rating.
1.2
General Description of the Works
The Works for the project is generally described below:
[to be specified by user]
[to be specified by user]
Refer to the PSD for the specific description of work requirements for the project.
1.3
Standards, Codes, Regulations and Technical References
1.3.1
Standards and Codes
Unless otherwise agreed by the SO, ensure all of the Works comply with the relevant requirements of
the Standards and Codes referenced in the body of the Specification. Alternative Standards and
Codes may be proposed for approval by the SO, provided it can be demonstrated that the alternative
Standards and Codes comply with the requirements of the standards specified. All Standards and
Codes quoted are the current version unless specific year references are noted.
In the event that the Standards or Codes are partially superseded or become obsolete, refer to the
latest edition or the approved substitution for the relevant clauses.
In case of conflicting requirements between the Codes, refer to the SO for resolution.
1.3.2
Regulations
The whole of the Works and materials are to be in accordance with the Building Control Regulations,
other regulations as set out by the Authorities having jurisdiction over the Works, and the relevant
bylaws unless otherwise stated.
Ensure that the Specification referred to are strictly adhered to when carrying out the Works, unless
otherwise directed.
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1.3.3
Technical References
Ensure that the Works comply with the relevant authority regulations and directions.
Where specified, be guided by the principles and methods as set out in the technical references when
carrying out the Works. Alternative methods and principles may be proposed in lieu of the referenced
document, subject to SOs acceptance, if it can be demonstrated that the specified quality or
performance of the Works can be achieved.
1.4
Trade Preamble
1.4.1
Ambiguity
Before commencing any works, obtain clarification or instructions in relation to any discrepancy or
ambiguity, which is discovered within and between the Specification work sections, and/or other
contract documents issued by the various parties.
1.4.2
Licences, Permits and Liaison with the Authorities
Be responsible to initiate the application for all necessary licences, permits, and to carry out all
necessary liaison with the Authorities, whenever necessary, for the satisfactory completion of the
Works.
Be responsible for ensuring that these licences and permits are obtained in good time.
1.4.3
Safety Regulations and Design for Safety
Strictly observe all necessary safety requirements to comply with the Workplace Safety and Health Act
and any other requirements from the Authorities having jurisdiction over the Works.
Comply to the Workplace Safety and Health (Design for Safety) Regulations, and to participate in any
Design for Safety (DfS) initiatives if so required for the project.
Responsible to execute the Works in a safe manner and ensure that the subcontractor and Designers
engaged are competent and provide them all relevant information needed for them to perform their
duties under the Workplace Safety and Health (Design for Safety) Regulations.
These Designers are as defined under the Workplace Safety and Health (Design for Safety)
Regulations.
Together with the relevant designers and subcontractors, attend the DfS review meeting held by the
DfS Professional, to address to hazards or risks identified and ensure that they are properly
managed through the execution GUIDE-3 of the Design Review Process.
Take over the DfS Register from the Consultants and continue from Guide 2 onwards. Refer to
Clause 5 "Site Safety" of this Section for further detail requirements.
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1.4.4
Safeguarding Properties Adjacent to Site
Propose and adopt site procedures and methods of working such as to limit to a minimum any
disturbance and vibration to the buildings around the Site.
Identify and implement protective measures necessary to safeguard the adjacent properties prior to
carrying out the Works.
Indemnify the Employer in accordance with contract conditions against all claims for loss and/or damage
to the adjoining properties by reason of the carrying out of the Works or by reason of insufficiency of
precautionary measures.
Refer to Section G01-010:Clause:1.7.7 for further detail requirements.
1.4.5
Maintenance Manual
Develop and submit, for the SOs acceptance, a strategy in the form of a maintenance manual and
logbook, to ensure that elements that are likely to deteriorate significantly can be replaced or rectified.
The maintenance manual and logbook are to describe the procedures for the satisfactory long- term
care and regular maintenance of the materials and components identified in the work sections, which
shall be carried out by the building owners. Include the following information, where appropriate:
(a)
An outline description of the installation and detailed description of specific items with product names,
types, serial numbers, etc.
(b)
The name, address and telephone number of each supplier, fabricator, finisher, installer, etc., involved in
the Works.
(c)
Recommendation on maintenance periods and planned preventive maintenance procedures.
(d)
Copies of manufacturers warranties or guarantees, service manuals, brochures, recommendations, etc.
(e)
Copies of test and approval certificates.
(f)
One original copy of documents showing "As Built" information and the like, relevant to the installation.
Submit the "As-Built" information in soft copies where directed by the SO. The Contractor shall compile
one single set of the information from various subcontractors for submission.
(g)
Compilation of a list of parts to be replaced periodically and the names and contacts of the suppliers.
(h)
Realignment and adjustment instructions where relevant.
(i)
Procedures for dismantling and reassembling.
(j)
Details of finishes, including colour and required maintenance.
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Logbook pages set up for recording the times of performance of the above procedures, sufficient in
number to receive the entries for a minimum of 10 years or otherwise directed. Show examples of
typical entries by recording any maintenance procedures (such as cleaning) performed during the
Contract Period and/or maintenance/defects liability period.
The forms of the maintenance manual and logbook are to be in A4 size, printed or typed on durable
printing paper, each page consecutively numbered, neatly bound in durable vinyl or similar hard cover,
and permanently labelled with the project name and date of issue. The Contractor shall compile one
single set of the information from various subcontractors for submission.
1.4.6
Testing Authority
When tests and checks are called for in the Specification, engage a suitably equipped organisation or
laboratory accredited under the Singapore Laboratory Accreditation Scheme (SINGLAS) and to SOs
acceptance, to carry out the tests and checks required.
1.4.7
Quality Control Plan
Prepare and submit a quality control plan for SOs acceptance. Include a set of procedures/actions to:
1.4.8
(a)
Ensure the understanding of the project brief.
(b)
Ensure a number of checks and verification are put in place in the work process to enable the delivery of
the brief.
(c)
Ensure the right person is employed to carry out the Works.
(d)
Ensure the Works are carried out based on proper operating instructions.
(e)
Ensure feedback and poor/defective works is picked up and attended to, and corrective/preventive action
is in place.
(f)
Ensure prior approvals are obtained from SO for any deviations from the Specification before Works
commence.
(g)
Ensure documents of all tests and quality checks as specified are properly done and kept as records.
Building Information Modelling (BIM)
Allow for the BIM requirements stipulated for the project, including all cost for necessary but not limited to
manpower, license, software and hardware. Such adoption shall be in line with latest Particular
Conditions for Building Information Modelling and Singapore BIM Guide published by Building and
Construction Authority.
1.4.8.1
BIM Particular Conditions
The Particular Conditions for Building Information Modelling shall refer to the BIM Particular Conditions,
published by the Building and Construction Authority.
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1.4.8.2
Singapore BIM Guide
The Singapore BIM Guide, published by the Building and Construction Authority, will be used for
references for the project.
1.4.8.3
BIM Execution Plan
Together with the Consultants and BIM Professional, develop a BIM Execution Plan at the start of the
project. The goals and the implementation details will be outlined in the BIM execution Plan.
1.4.9
As-built Drawings
Contractor to obtain authority approved plans in CAD from SO. These plans must be updated to capture all
deviations or amendments, including those captured in SO’s Instructions (SOI), Project Manager’s
Instructions (PMI), Architect’s Instructions (AI), Engineer’s Instructions (EI), Request for Information (RFI),
Construction sketches, etc. Contractor is to submit such revised plans as as-built drawings to SO for record
and authority record plan submission. The as-built plans shall be submitted progressively floor by floor not
later than two weeks from casting date. Also, the Contractor is to reflect all structural deviations in the Final
As built Models.
1.5
Performance Criteria
1.5.1
General Requirement
Engage methods and resources that will ensure the Works achieve the specified quality within the
agreed programme and cost.
1.5.2
Environment
Ensure the carrying out of the Works will not cause unacceptable pollution, noise, erosion and vibrations
to the environment as stipulated by the NEA and other relevant Authorities.
1.5.3
Code on Accessibility
Comply to the Code on Accessibility in the Built Environment and its latest updates.
1.5.4
Buildability (Buildable Design and Constructability)
Comply to the latest amendments on Building Control Act and Regulations on Buildability and
Productivity.
The Contractor is responsible to achieve the Constructability Score required for the project and declare
the Constructability Score achieved and on the Certificate of Compliance of Constructability Score.
1.5.5
Good Industry Practices
Adopt the details of good pratices as appended in BCA publications and advisories on the Good
Industry Practices Guide Book.
1.6
Materials
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1.6.1
Materials Generally
Products shall be new unless otherwise specified. All materials shall be supplied clean, undamaged and
in good condition ready to be used for the Works.
For products with a limited shelf life, ensure no parts or whole are expired.
Where a choice of manufacturer or source is allowed for any particular product, supply the whole
quantity required as the same type and from the same manufacture and/or source unless otherwise
approved. Produce written evidence of sources of supply when requested. Ensure that the whole
quantity of each product supplied is of consistent kind, size, quality and overall appearance.
Ancillary products and accessories shall be of a type recommended by the main product manufacturer,
unless otherwise specified.
1.6.2
Ordering of Materials
Unless otherwise directed, do not place orders for materials before the sources and samples of the
materials have been approved and the results of any preliminary tests required by the Specification
have been accepted by the SO.
1.6.3
Certificates for Materials
All materials and products shall be manufactured and tested in accordance with the specified or
appropriate Standard. All materials and products delivered to the Site shall bear the manufacturer's
name, brand name or any other data required to verify compliance with the specified requirements.
Where appropriate, provide certificates from the supplier or test agencies verifying such compliance.
Include, whenever applicable, the location in the Works or the delivery or batch which the certificate
represents.
Where certificates of manufacture or tests are not available for materials proposed for use in the
Works, carry out independent testing to determine compliance with the specified requirements
where directed by the SO.
1.6.4
Storage of Materials
Store all materials in a manner, which is not detrimental to their use in the Works and in accordance
with any specified requirements.
Ensure that the storage facilities and the loadings resulting from the storage will not adversely affect the
construction, the building and other buildings/amenities nearby. Engage specialist advice if appropriate.
Do not permit the storage of materials, components or equipment on new or partially completed work
without prior approval.
1.6.5
Rejected Materials
Immediately remove from the site, all materials which are unidentified or do not comply with the
Specification.
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1.7
Workmanship
1.7.1
Workmanship Generally
Ensure that all works are carried out:
1.7.2
(a)
In accordance with the specified methods and procedures where applicable.
(b)
In accordance with good building practice.
(c)
In accordance with the manufacturers instructions where applicable.
(d)
By suitably qualified and experienced personnel.
(e)
With required site supervision by qualified personnel.
Co-Ordination of Drawings
Check all drawings and schedules to ensure that there is sufficient information to carry out the Works
and that all the instructions, drawings and schedules provide compatible information on the Works to
be carried out.
In the event of any discrepancy being found between the contract drawings and/or schedules, and other
contract documents, notify the SO immediately for resolution the SOs decision shall be final.
1.7.3
Setting Out and Levels
1.7.3.1
Accuracy
Arrange the setting out, erection, juxtaposition of components and application of finishes in such
manner as to ensure:
1.7.3.2
(a)
Compliance with specified tolerances.
(b)
Satisfactory fit at junctions.
(c)
No visually unacceptable changes in plane, line or level.
(d)
True, regular finished appearance.
Levels
Site levels, either spot or contour, and all other levels shown in the drawings are established with
respect to the datum of 100.00 m at mean sea level. Check and verify all existing and proposed
levels as indicated in the drawings. Highlight and resolve any discrepancy prior to the commencement
of the Works.
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1.7.4
Delivery, Storage and Handling
Deliver materials and products to the Site with labels showing brand name, product name and
manufacturer's batch number.
Store materials in accordance with manufacturer's recommendations. Use in order of delivery and
before expiration of the shelf life date.
1.7.5
Protection of Products and Components
Take measures to prevent overstressing, distortion and other damage to the products.
Keep products and components clean and free from contamination. Prevent staining, chipping,
scratching or other disfigurement, particularly of products exposed to view in the finished work.
Keep dry to prevent premature setting, moisture movement and similar defects. Where appropriate store
off the ground and allow free air movement between stored products.
Prevent excessively high or low temperatures and rapid temperature changes in the products.
Protect adequately from rain, damp, sun and other elements as appropriate. Ensure that products are
of a suitable temperature and moisture content at time of use.
Ensure that sheds and covers are of ample size, in good weatherproof condition and well secured.
Keep different types and grades of products separately and adequately identified.
Keep products in their original wrappings, packings or containers until immediately before use. Wherever
possible, retain protective wrappings after fixing until shortly before handing over to the Employer.
Ensure that protective measures are fully compatible with and not prejudicial to the products and
materials.
1.7.6
Suitability of Conditions at the Start of Works
Provide all trades with necessary details of related types of work. Before starting each type of work,
ensure that:
1.7.7
(a)
Previous work is appropriately complete, in accordance with the project documents, to a suitable standard
and in a suitable condition to receive the new work.
(b)
All necessary preparatory work has been carried out, including provision for services, openings, supports,
fixings, damp-proofing, priming and sealing.
(c)
The environmental conditions are suitable.
Execution of Works
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1.7.7.1
Methods
Carry out the Works in accordance with accepted methods and equipment.
1.7.7.2
Allowance for Movements
Ensure that the performance, appearance and proper functioning of the Works are not affected by any
movement, settlement, deflection, expansion or contraction that can be reasonably expected to
occur in the building or the Works.
Where applicable, form joints between the Works and adjacent works to accommodate possible
movements, settlement, deflection, expansion or contraction between the works.
1.7.7.3
Monitoring of Adjacent Structures
Provide proposals for surveys and monitoring of movement and vibration in adjacent structures and
services before work commences and during the course of the Works.
Submit the assessment of the effect of wall deflection and ground settlement to adjacent properties and
the proposed control limits.
1.7.7.4
Instrumentation and Monitoring
Provide instrumentation to monitor the ground movement, vibration and condition of adjacent
properties. Refer to the drawings for the schedule of instrumentation required. If necessary or as
required by the Authorities, propose and provide additional instrumentation and monitoring for records.
Take cognisance of and co-ordinate with other contractors on site who the persons may be carrying out
instrumentation and monitoring works to avoid duplication of installation and readings.
Refer to Section C02-050 "Instrumentation and Monitoring" for further details.
1.7.7.5
Application/Installation of Products and Components
Use or fix each product and component in accordance with manufacturer's recommendations. Inform
the SO if recommendations conflict with any other specified requirement.
Provide suitable packings at screwed and bolted fixings to take up tolerances and prevent distortion.
Adjust the location and fixing of components and products so that joints which are opened to view are
even and regular.
Ensure that all moving parts operate properly and freely. Do not cut, grind or plane pre-finished
components and products to remedy binding or poor fit without approval.
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1.7.8
Holes, Chases, Inserts and Fittings
Obtain approval for the size and position of any hole, chase, insert or fixing required before the related
work begins. Unless otherwise agreed, form all holes and chases and build in any inserts or fixings at
the time of construction. Do not cut or drill any part of the Works without approval.
Do not cast any conduits, recesses, pipes, etc. inside structural columns, walls, beams or slabs unless
otherwise agreed.
1.7.9
Protection of Works
Take all necessary precautions to prevent damage to the Works from rain and other hazards, and due
to the other works in progress, until hand over.
1.7.10
Defective Work
Where, in the opinion of the SO, any of the finished work or materials or workmanship in any part of
the Works fail to comply with the Specification, that part of the Works will not be accepted and may
be classified as defective.
All work classified as defective shall be cut out and removed from the Works and replaced or otherwise
dealt with in accordance with the Conditions of Contract. Propose and carry out suitable remedial
measures to the SOs satisfaction.
The extent and nature of any measures required as a result of defective work shall be determined by
the SO.
1.7.11
Cleaning Up
Where, in the opinion of the SO, any of the finished work or materials or workmanship in any part of
the Works fail to comply with the Specification, that part of the Works will not be accepted and may
be classified as defective.
All work classified as defective shall be cut out and removed from the Works and replaced or otherwise
dealt with in accordance with the Conditions of Contract. Propose and carry out suitable remedial
measures to the SOs satisfaction.
The extent and nature of any measures required as a result of defective work shall be determined by
the SO.
1.8
Verification and Submission
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1.8.1
Records and Certificates
Unless otherwise directed, maintain 3 copies of records of all inspections and tests performed to
substantiate conformity with the Contract Specification, including those carried out by subcontractors
and/or third party testing agencies and manufacturers' or suppliers' certificates of test.
Retain one copy of these records on site and make available for inspection at any time. Submit the
other 2 copies to the SO and the Employer respectively and progressively. On completion of the
Works, hand over all records to the SO, unless otherwise agreed.
Submit to the SO, without delay, any records which indicate work or materials not complying with the
Specification, in order that proposals for any rectification may be assessed and carried out in good
time.
1.8.2
Tests to Establish Acceptability of Works
In the event of failure to comply with the requirements of the Specification, propose suitable tests to
establish the acceptability of the Works and be responsible for any consequential costs and delays.
1.9
Stamp Duties
All documents required by or arising out of or in connection with this Contract shall be properly stamped
to comply with the Stamp Duties Act. The cost and expense arising out of this obligation, including all
stamp duties required, shall be borne by the Contractor and shall be deemed to have been allowed
for in the Contract Sum.
1.10
TOL Fee for Land Outside Contract Boundary
Where the Contractor requires land outside the contract boundary for the setting up of construction
equipment and other temporary facilities for the Works, the Contractor shall check on the availability of
such land and apply to the relevant Authority for the use of such land. In the event the relevant
Authority allows the Contractor the use of such land, the Contractor shall at its own cost and expense
comply with all the terms and conditions, pay any TOL (Temporary Occupation Licence) fees, bear all
costs and expenses for the use and maintenance of and access to the said land imposed by the
relevant Authority.
Any materials or goods stored at such land shall be considered unused materials or goods not delivered
to Site.
1.11
Provisional Sum Items
Where Provisional Sum Items are included in the Contract, the Provisional Sum Items shall include all
costs necessary in carrying out or supplying the Work, materials or goods. These Provisional Sum Items
shall include the Contractor's profit and overheads but shall be nett of trade and cash discounts.
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1.12
Prime Cost Sums
Where Prime Cost Sums (referred to as PC Sum for the purposes of this subclause) are provided for
any work, materials or goods, these sums shall be inclusive of carriage but exclusive of Contractor's
profit and attendance. These PC Sums shall also be net of trade and cash discounts.
Allow and separately price for profit and attendance in respect of such PC Sum in the Form of Tender.
Deduct PC Sum from the Contract Sum and in lieu thereof add the sums due to the Contractor for the
said work, materials, or goods. The sum allowed by the Contractor in the Contract for attendance in
respect of any PC Sum shall be fixed regardless of whether the actual sum expended is greater or
lesser than the PC Sum. In respect of profit, the amount to be paid shall be the percentage quoted by
the Contractor against the actual sum expended in relation to the PC Sum.
Should the work, materials or goods for which a PC Sum is provided in the Contract be not required,
or if the Employer chooses to carry out or supply the aforesaid work, materials or goods by its own
workmen or by other contractors, which the Employer is contractually entitled so to choose, then such
PC Sum together with the profit and attendance allowed by the Contractor in the Contract shall be
deducted in full from the Contract Sum.
Should the Contractor be engaged or instructed to carry out or supply any work, materials or goods
under a PC Sum, the profit and attendance allowed by the Contractor in the Contract in respect of the
PC Sum shall be deducted in full from the Contract Sum. In such event, the amount to be paid to the
Contractor for the work, materials or goods shall be inclusive of the Contractor's overheads and profit
for the work, materials and goods.
1.13
Overclaim Leading to Overpayment
If at any time during the Contract Period (including any extension thereof), the Contractor is found to
have over-claimed and was paid for more than the value of the Permanent Works carried out and/or
approved unfixed materials at the Site, the SO shall be empowered to deduct from the Contractor's
subsequent payments the sum overpaid together with the Employer's charge, and interest calculated at
the prevailing rate.
1.14
Existing Ground / Road Levels
The existing ground / road levels / drain invert levels as shown in the drawings are approximate.
Note that existing ground /road levels and drain invert levels may not necessarily be the same as
shown in the drawings. Ascertain this and visit the Site prior to the tender and is include whatever
extra cost of cut and fill in the Contract Sum. In the event of the Contractor failing to visit the Site, the
tender shall be deemed to have been submitted with its satisfaction of the actual levels on Site and
other related ground conditions. The Contractor is deemed to have made necessary provision in the
Contract Sum to cater for additional earthwork arising from the difference in levels found on site and
that shown in the drawings, and no claims or compensation shall be entertained.
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1.15
Raising or Lowering of Existing Sewer Manholes and Other Services Manholes
Include in the Contract Sum the cost of raising or lowering of existing sewer manholes and other
services manholes/chambers, and their related works within the contract boundary to suit and match
the proposed driveways and platform levels.
1.16
Work Method and Trade Demonstration
Submit to the SO for approval the work methods of various trades as required by the SO to ensure
good in-process quality control and reasonably acceptable final workmanship. A marking system,
where applicable, showing, inter alia, the control, grid and level reference lines shall be included in the
work methods.
Ensure that subcontractors engaged for each trade shall also comply with the work methods
approved by the SO. As instructed by the SO, conduct trade demonstrations for all critical work
methods as approved prior to full scale production in the Contract.
Should it appear to the SO at any time that the work methods proposed by the Contractor will not
ensure good workmanship in the Works, the SO may require the Contractor to make at his own cost
and expense such modifications to the original work methods as the SO may consider necessary or
appropriate.
Employ only skilled workers who are capable of executing the Works in accordance with the work
methods approved by the SO. When there is a change in subcontractors, the SO may instruct the
Contractor to re-conduct the relevant trade demonstration if deem necessary.
Approval by the SO of the Contractors work methods, revised work methods or any details and
information provided under this subclause shall not in any way relieve the Contractors liabilities or
obligations under the Contract.
1.17
Site Layout Plan
After the Contract is awarded, submit a site layout plan to the SO indicating proposed locations of all
temporary structures (for example site offices, workers' quarters, stores, hoistways, construction
equipment and labour lines) for approval before their erection. Notwithstanding such approval, any
such structures shall be relocated at the Contractors own cost and expenses when required to do so
by the SO.
All such materials and structures shall be kept away from proposed roads, driveways, car parks and
services lines.
Should any hoistway or structure be erected without the approval of the SO, pull down and re- erect
the hoistway or structure in an approved position within 7 days from the date of instruction by the SO.
Provide for the maintenance of all such structures in a clean, hygienic and safe condition for the duration
of the Works.
All such structures and hoistways shall be removed on completion of the Works.
1.18
Site Offices
Within an agreed period of time from the date of taking possession of the Site, erect site offices complying
with the requirements of the MEWR and remove them on completion of the Works or at a time approved
by the SO. Submit proposals for the design (inclusive of PE calculations),
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configuration and layout for the approval of the SO taking full consideration the site constraints and
conditions.
The following rooms shall have at least the minimum stipulated areas and complete with basic facilities,
fittings and furniture,which can be made available at all times for use by the SO and the Employer:
.
S/N
Facilities, Furniture and
Fittings
No. of Items
.
.
.
SO Room
Resident
Site Staff/
Consultant
Room
Meeting
Room
Sample
Room
.
1.
Room (Minimum size andable to
accommodate all facilities specified)
[to be
[to be
specified by specified by
user]
user]
[to be
specified
by user]
[to be
specified by
user]
.
2.
Tables and Chairs
.
.
.
.
.
[to be
(a) 1.5m x 0.8m office table complete [to be
with at least 3 drawers
specified by specified by
user]
user]
[to be
specified
by user]
[to be
specified by
user]
.
.
(b) 1.5m x 0.8m working table
complete with storage space for
drawings
[to be
[to be
specified by specified by
user]
user]
[to be
specified
by user]
[to be
specified by
user]
.
.
(c) 0.8m wide side tables for
computer and peripherals
[to be
[to be
specified by specified by
user]
user]
[to be
specified
by user]
[to be
specified by
user]
.
.
(d) 1.2m x 0.8m table
[to be
[to be
specified by specified by
user]
user]
[to be
specified
by user]
[to be
specified by
user]
.
.
(e) Chairs with hand rests
[to be
[to be
specified by specified by
user]
user]
[to be
specified
by user]
[to be
specified by
user]
.
.
(f) Chairs without hand rests
[to be
[to be
specified by specified by
user]
user]
[to be
specified
by user]
[to be
specified by
user]
.
.
(g) High Chairs without handrests (for
working table)
[to be
[to be
specified by specified by
user]
user]
[to be
specified
by user]
[to be
specified by
user]
.
3
Steel Cabinet complete with
Shelves and Double-Leaf Doors with
lock
[to be
[to be
specified by specified by
user]
user]
[to be
specified
by user]
[to be
specified by
user]
.
4
Soft Board complete with
Accessories
[to be
[to be
specified by specified by
user]
user]
[to be
specified
by user]
[to be
specified by
user]
.
5
White Board complete with
Accessories
[to be
[to be
specified by specified by
user]
user]
[to be
specified
by user]
[to be
specified by
user]
.
6
Key cabinet
[to be
[to be
specified by specified by
user]
user]
[to be
specified
by user]
[to be
specified by
user]
.
7
Air-Conditioner of Minimum 10,000
BTU Output
[to be
[to be
specified by specified by
user]
user]
[to be
specified
by user]
[to be
specified by
user]
.
8
Telephone Installation
.
.
.
.
.
(a) Separate telephone line
[to be
[to be
specified by specified by
user]
user]
[to be
specified
by user]
[to be
specified by
user]
.
.
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.
.
(b) Telephone set
[to be
[to be
specified by specified by
user]
user]
[to be
specified
by user]
[to be
specified by
user]
.
9
Drawing Rack complete with
Drawing Holders
[to be
[to be
specified by specified by
user]
user]
[to be
specified
by user]
[to be
specified by
user]
.
10
Electrical Installation, Connections and
Accessories
.
.
.
.
.
(a) Lighting lux level
[to be
[to be
specified by specified by
user]
user]
[to be
specified
by user]
[to be
specified by
user]
.
.
(b) 13 Ampere socket outlet
[to be
[to be
specified by specified by
user]
user]
[to be
specified
by user]
[to be
specified by
user]
.
.
(c) 15 Ampere socket outlet
[to be
[to be
specified by specified by
user]
user]
[to be
specified
by user]
[to be
specified by
user]
.
.
(d) Data point
[to be
[to be
specified by specified by
user]
user]
[to be
specified
by user]
[to be
specified by
user]
.
.
(e) Emergency light
[to be
[to be
specified by specified by
user]
user]
[to be
specified
by user]
[to be
specified by
user]
.
The doors leading to the SOs room, the Resident Technical Officers room and the meeting room
shall be provided with locksets and all the keys to the locksets shall be given to the SO. Allow for the
maintenance of the site offices, rest areas and all the facilities, furniture and fittings therein in a clean,
habitable and good working condition to the satisfaction of the SO. The Contractor shall pay all
charges for the provision and use of the telephone and electricity at the site offices.
Should the Contractor fail to provide any of the aforementioned facilities, furniture and fittings after the
commencement date of the Contract Period, the SO shall forthwith purchase and provide the same
on the Contractor's behalf and all costs and expenses for such purchase and provision plus charges
shall be recovered by the Employer from any monies due or becoming due to the Contractor or be
recovered as a debt due by the Contractor to the Employer.
1.19
Provision of Equipment, Apparatus, Devices, etc.
1.19.1
Facsimile Machine
Provide 1 plain paper (A4 size) facsimile machine at the site office. Facsimile machine of the
thermal paper type is not acceptable. Keep such machine in the Resident Site Staff room
throughout the Contract Period (including any extension thereof). The facsimile machine shall be for
the exclusive use by the SO and/or Employer's officers only. Another facsimile machine should be
provided for the Contractors own use.
Pay all charges, costs and expenses and be responsible for the continuous proper, good and efficient
working conditions and maintenance of such facsimile machine. Produce the maintenance agreement
with the vendor to the SO for checking when requested. The maintenance agreement shall cover the
whole duration of the Contract Period (including any extension thereof).
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1.19.2
Digital Camera on Site
Provide a digital still camera on the Site throughout the Contract Period (including any extension
thereof), for the purpose of photographing site occurrences (within the Site) by the SO.
The digital still camera shall have zooming functions and be capable of taking pictures at a digitised
resolution of at least 10 million pixels. The digital still camera shall have an expandable and removable
memory storage media with a minimum capacity of 128 GB, and be provided with all the necessary
software and accessories for editing and transferred digital images from the camera to the computer
hardware. The Contractor shall bear all the costs and expenses incurred arising from usage of the
digital camera and shall be responsible for its continuous and proper functioning.
1.19.3
Torch Lights
Provide sufficient torch lights on the Site at all times for use by the SO, Resident Site Staff and/or
representatives from other Authorities. These torch lights shall be in good working condition and
sufficiently bright enough for use.
1.19.4
Metal Detector
Provide a battery-operated portable metal detector for the purpose of detecting metal reinforcement
embedded in cement mortar joints of brickwalls. The detector must have either a light or buzzer
indicator to indicate the presence of metal.
1.19.5
Moisture Meter
Provide a portable, battery operated, digital LCD display moisture meter with integral electrode pins for
measuring moisture content of timber doors and frames delivered to the Site. The moisture meter
shall be capable of measuring actual moisture content of wood in the range from 8% to 44%
(minimum) with a 1% indicating tolerance at 0°C to 40°C ambient temperature. The meter shall also
possess a built-in device for performing simple calibration checks.
1.19.6
Personal Protection Equipment (PPE)
Provide sufficient Personal Protection Equipment (PPE) such as safety helmets, safety boots, goggles
and ear plugs for use by the Employer's officers and visitors visiting the Site throughout the Contract
Period (including any extension thereof). The ownership of the safety helmets and safety boots shall be
reverted back to the Contractor upon the satisfactory completion of the Works.
Immediately replace those PPE which the SO considers to be not in good working condition.
1.19.7
Stationery for Resident Site Staff / Consultants
Provide stationery and other devices for site use by the Employer's officers upon commencement of the
Works.
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1.19.8
Photo Copying Machine
Provide one plain paper photocopying machine at the site office with the following Specification:
(a)
minimum [to be specified by user] ppm in black and white
(b)
Support paper up to 160gsm and A3+
(c)
Auto paper selection
(d)
Auto response sensor
The photocopying machine shall be kept in the Resident Site Staff room throughout the Contract
Period (including any extension thereof). The photocopying machine shall be for the exclusive use by
the SO and/or Employers officers only. Another photo copying machine should be provided for the
Contractors own use.
Pay all charges, bear all costs and expenses and be responsible for the maintenance of such
photocopying machine. Produce the maintenance agreement with the vendor to the SO for checking
when requested.
The maintenance agreement shall cover the whole duration of the Contract Period (including any
extension thereof).
1.20
Provision of Temporary Site Facilities/Utilities
1.20.1
Access Roads and Protective Crossings
Repair and maintain all access roads serving the Site and provide temporary protective crossings
over existing drains, channels, footways, etc. throughout the Contract Period (including any extension
thereof). The Contractor shall be responsible for making good all damage and/or clearing away on
Completion to the requirements of the relevant Authorities and to the satisfaction of the SO.
1.20.2
Temporary Electricity Supply and Installation
Engage a LEW of appropriate grade to design and in charge of all temporary electrical installations
necessary for building operations and works of engineering construction in accordance to SS 650-1; for
site offices, meeting rooms, dormitories and etc. located within construction site in accordance to SS
638, at the date of closing of the Tender. Throughout the Contract Period and any time period when
liquidated damages are imposed under the Contract, the Contractors LEW shall ensure good safety
standards and practices and including the following:
(a)
For redevelopment sites, the Contractor is strongly encouraged to use M/s PowerGrid Ltds power
supply to provide temporary electricity supply during the construction stage. All electrical generator sets
shall be licensed with valid EMA licence. However, when the generator is used for the passenger cum
material hoist and other general purposes, the minimum capacity of the generator for each block shall be
upgraded to 100 kVA.
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1.20.3
(b)
The electrical switch board which holds the ELCB shall be housed in a switch box located at least 1.5 m
from the floor level.
(c)
Socket-outlet assembly complete with miniature circuit breakers (MCBs) and residual current operated
circuit breakers (RCCBs) shall be provided at each storey of the building block. The installation shall last
the entire Contract Period unless authorised to be removed earlier by the SO or when permanent
electricity supply is secured (whichever is earlier). The temporary incoming supply cable located within
the precast refuse chute shall be supported with insulated lock bands. Upon termination of the temporary
electricity supply, all cables and lock bands installed in the precast refuse chute shall be removed and the
surface of the precast refuse chute shall be made good to a smooth finish.
(d)
All sheaths of cables, sockets outlets and plugs are in good working condition.
(e)
All cables are properly bound and do not cause obstruction to passageways, walkways and stairs.
(f)
All cables are properly supported with L-shaped galvanised steel brackets or insulated lock bands and
placed at a suitable height, away from any source which cause mechanical damage.
(g)
All plugs, socket-outlets, socket-outlet assembly (SOA), cable couplers and plug adaptors are to be of
the standard industrial type and of minimum classification of latest edition SS 638 and SS 650-1.
(h)
The supply to provide artificial lighting shall be taken from the socket-outlet assembly located at each
storey. Fluorescent lighting of 1 200 mm enclosed in suitable mechanical enclosure to a minimum
classification of IP 44 shall be used to provide lighting or to achieve a minimum lighting level of 400 lux.
(i)
Provide sufficient temporary lighting, according to the instruction of the SO, for workers/subcontractors to
carry out in-process construction works such as internal plastering/skimming, wall and floor tiling,
application of water-proofing membrane etc. within the units or common areas of the building under
construction.
Temporary Use of Lift
For each building block in the Works designed with lift facilities, when needed during the progress of
works, seek the SOs approval for the temporary usage of one lift upon completion of lift testing and
commissioning by the lift subcontractor. All costs and expenses incurred in complying with the
provisions of this clause shall be deemed to be included in the Contract Sum.
The temporary use of the lift shall be subjected to the terms and conditions stipulated hereunder. Such
terms and conditions shall be incorporated into the agreement to be executed between the Contractor
and the lift subcontractor. The terms and conditions shall be as follows:
(a)
The Contractor shall seek the approval of the SO for the use of the lifts.
(b)
The Contractor shall arrange for a designated person to certify that the lifts are for temporary use and
seek approval from MOM before it can be used.
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1.21
(c)
The Contractor shall provide proper protection such as plywood, adhesive tapes, etc. to the lift cages,
floors, car doors, architraves, transoms and landing doors, etc. The Contractor shall ensure that the
protection for the lifts is always in a proper condition. Any physical damage to the lifts shall be the
responsibility of the Contractor.
(d)
The Contractor shall engage a full-time lift attendant to operate each lift. Under no circumstance shall a lift
be left unattended when it is in operation.
(e)
The Contractor shall ensure that the lifts are not over-loaded.
(f)
The Contractor shall take up additional insurance for the use of the lifts as temporary use lifts and Public
Liability coverage, naming the Employer and the lift subcontractor as the co-insured, for the period of
usage. Copies of the insurance policies shall be given to both the SO and the lift subcontractor before
the lifts are allowed to be used. Alternately, the Contractor may pay the lift subcontractor for taking up the
insurance and public liability coverage on its behalf.
(g)
The Contractor shall be responsible for the daily maintenance of the lifts, such as cleaning up the cages
and sills in order to prevent unnecessary breakdown and damage to the lifts.
(h)
The lift subcontractor shall service the lifts once a month during normal working hours.
(i)
Smoking is strictly prohibited in the lifts.
(j)
At least 3 days prior to handing over each building block to the Employer, a joint inspection shall be
conducted between the Contractor and the lift subcontractor for the purpose of handing the lift back to the
lift subcontractor. Any damage that occurs during or as a result of or arising from the temporary usage of
the lift which affect the handing over of the lift to the Employer shall be the responsibility of the Contractor.
All costs and expense for rectification and repair shall be borne by the Contractor, subject to verification
by the SO.
Protective Roof for Temporary Site Structures
Provide appropriate protective materials for the roof of these temporary structures. The protective
material shall be made of 18 mm thick timber ply.
For site office and workers' quarters, the timber ply shall be laid in dual double layers; with one double
layer laid just beneath the metal roofing sheet and another double layer at the bottom of the steel truss
system supporting the metal roofing sheet. For all other temporary structures, such as toilets, carpenter
yards, etc. the protective timber roof shall be laid in single double layer beneath the roofing sheet.
However, at the sole discretion of the SO, such protective materials may not be necessary if the
temporary structures are deemed far beyond the nearest building block under construction. Under such
cases, there shall be no adjustment to the Contract Sum. The Contractor's PE shall consult the SO on
these protective roofs before proceeding with the design of the temporary structures.
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1.22
Construction Site Hoarding
Submit a complete set of the hoarding workshop drawings to be endorsed by the Contractors PE for
SOs approval. The proposed layout of the images and designs used on the hoarding shall be
indicated on the plans and elevation of the workshop drawings submitted.
All sites will use flat panel hoardings on all sides of the contract boundary lasting throughout the Contract
Period including any period when liquidated damages are imposed under the Contract. The hoarding
panels shall be white or off-white zincalume steel or galvanised steel flat panel.
Maintain and upkeep the hoarding panels in good condition. As and when instructed by the SO, replace
the hoarding panels to the satisfaction of the SO, at the cost and expense of the Contractor.
As and when instructed by the SO, remove or relocate all or part of the hoarding panels with the
signage and reinstate the affected grounds to the satisfaction of the SO at the cost and expense of
the Contractor. On satisfactory completion of the Works, the hoarding panels with the signage shall
be cleared away upon the approval of the SO.
1.22.1
Signage on Hoarding
Provide images for the "Construction in Progress" and way-finding signage to inform the public that the
project is under construction and for guiding the public on the correct way to take around a
construction site.
The "Construction in Progress" and way-finding signage shall be mounted conspicuously on the white or
off-white zincalume steel or galvanised steel flat panel hoarding throughout the external perimeter of
the contract boundary.
(a)
Ensure that the signage is printed on adhesive laminate film that is waterproof, fade- proof and durable
against the weather. The colour setting on the printer shall be Adobe RBG. The signage shall be stuck
onto the flat panel hoarding.
(b)
The signage shall be mounted at areas of high pedestrian traffic and/or high visibility and shall last
throughout the Contract Period including any period when liquidated damages are imposed under the
Contract.
(c)
The size of the "Construction in Progress" signage shall be 4.0 m in height and 2.7 m in length on a 6.00
m high flat panel hoarding. It should be scaled proportionately for hoarding of other heights. The signage
shall be mounted at a comfortable viewing angle and level for the public. Seek the SOs approval for the
appropriate size for the way- finding signage.
(d)
The signage shall not block or obstruct the hoarding design with images depicting the overall
perspectives of the project, community images and project information and construction progress at all
times. Seek the SOs approval of the appropriate placement of the signage. The SO shall instruct the
Contractor to remove the signage should it be placed at an inappropriate location, at the cost and
expense of the Contractor.
(e)
Conduct regular inspection of the condition of the signage to ensure the signage are in good condition.
Should any signage be found to have faded or damaged, the SO shall instruct the Contractor to replace
the defective signage, at the cost and expense of the Contractor and to the satisfaction of the SO.
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1.23
Site Management
Within 14 days from the date of the Letter of Acceptance, submit to the SO for his approval the following
details on site planning:
(a)
Site organisational structure
(b)
Names, roles and responsibilities of Contractor's site management, technical and supervisory staff
(c)
Manpower schedule for each trade
(d)
Schedule of heavy equipment and machinery
(e)
Measurement Plan and Survey method
(f)
Safety Management System
Within 30 days from the date of the Letter of Acceptance, submit to the SO for his approval the overall
construction programme for each building block and/or phases of Works of the entire project.
Furnish the SO with such further details and information as the SO may require in regard to the above
items.
Should it appear to the SO at any time that the site planning proposed by the Contractor is not able to
ensure smooth progress and good workmanship in the Works, the SO is empowered to require the
Contractor to make, at the Contractors own cost and expense, all necessary modifications to the
plans.
Approval by the SO of the Contractor's site planning details, revised site planning details and further
information provided under this subclause shall not in any way affect, vary or relieve the Contractor's
liabilities or obligations under the Contract.
At least 14 days before the commencement of the Works by the subcontractors or the supply of the
materials by the manufacturers / suppliers, submit the names of its subcontractors for the Works and
the manufacturers / suppliers of the materials to the SO. Where there are changes made by the
Contractor to its subcontractors / suppliers, such information shall be submitted to the SO 14 days prior
to the commencement of the Works or supply of materials.
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1.24
Employment of Contractors Site Personnel
Employ the site personnel as specified in the table below and station them full-time on site upon the
approval from the SO.
The Project Manager, Workplace Safety and Health Officer, Environmental Control Officer, Security
Guard and at least 50% of the total number of the stipulated Site Supervisors (Architecture,
Structural, or Mechanical and Electrical Engineering) shall be employed and be full time on site from
the commencement date of the Contract. The Contractor is given up to one month from the
commencement date to deploy the Workplace Safety and Health Co- ordinator, Site Clerk and the
rest of the Site Supervisors.
Upon their employment, the site personnel shall be full time on site throughout the construction period
including any period when liquidated damages are imposed under the Contract, unless otherwise
approved by the SO.
1.24.1
S/N
Type of Personnel
Number of Each
Type
of
Personnel to be
Employed
Fully Agreed andAccepted Rate by the
Contractor andthe Employer For the Cost and
Expense Deemed to be Allowed by the
Contractor for the Employment of Each
Personnel
1
Project Manager
[to be specified
by user]
$ [to be specified by user]permonth
2
Workplace Safety &
Health Officer (WSHO)
[to be specified
by user]
$ [to be specified by user]permonth
3
Workplace Safety &
Health Co-ordinator
[to be specified
by user]
$ [to be specified by user]permonth
4a
Site
Supervisor
Architectural
Structural Works
for [to be specified
& by user]
$ [to be specified by user]permonth
4b
Site
Supervisor
for [to be specified
Mechanical & Electrical by user]
Works
$ [to be specified by user]permonth
5
Environmental Control
Officer
(ECO)
[to be specified
by user]
$ [to be specified by user]permonth
6
Security Guard
[to be specified
by user]
$ [to be specified by user]permonth
7
Site Administrator
[to be specified
by user]
$ [to be specified by user]permonth
8
Customer
Relations [to be specified
Officer
(CRO)
for by user]
Building
Maintenance
Team
$ [to be specified by user]permonth
Qualifications/Experience/Responsibilities of Site Personnel
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1.24.1.1
Project Manager
The Contractor's Project Manager shall be qualified, competent and possess the skill, knowledge and
ability to manage and co-ordinate the project effectively. The Project Manager shall be the Contractor's
Representative as required under the Contract.
The Project Manager shall possess the following minimum academic qualifications and experience:
(a)
1.24.1.2
For Contract Sum less than $50 million, the candidate shall have:
(i)
A degree in Architecture, Civil/Structural/Electrical/Mechanical Engineering, Construction
Management, Building Science or Quantity Surveying with 3 years of relevant post-graduate
working experience in the building construction industry. The degree shall be recognized by the
respective Professional Bodies professional institutions or Building and Construction Authority; or
(ii)
A diploma in Architecture, Civil/Structural/Mechanical/Electrical Engineering, Building Science,
Building Management, Construction Management, Building Services Engineering and at least
8 years of relevant working experience in the building construction industry. The working
experience should preferably be working on past projects and shall be recognised by SO as
relevant working experience.
(b)
For Contract Sums of $50 million and above, the candidate shall have a Degree in Architecture,
Civil/Structural/Electrical/Mechanical Engineering, Construction Management, Building Science or
Quantity Surveying with 5 years of relevant post- graduate working experience in the building
construction industry. The degree shall be recognized either by the respective Professional Bodies,
professional institutions or Building and Construction Authority.
(c)
Regardless of the Contract Sum, the Project Manager shall possess a Certificate in Construction
Productivity Management recognised either by the respective Professional Bodies, professional institutions
or Building and Construction Authority. The Project Manager who is without "Certificate in Construction
Productivity Management" shall attend the course conducted by BCA Academy and obtain it within 12
months upon his employment at the site. Where there is a need to attend the course conducted by BCA
Academy, the fee will not be reimbursed.
Workplace Safety and Health Co-ordinator / Workplace Safety and Health Officer (WSHO)
The Contractor's Workplace Safety and Health Co-ordinator shall possess recognised and approved
certification in construction safety to take charge of all matters related to safety. The said Workplace
Safety and Health Co-ordinator shall spend their time fully performing the following:
(a)
To supervise safety and promote safety conduct
(b)
To inspect and rectify any unsafe place of work
(c)
To correct any unsafe practice
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(d)
To ensure that the provisions of the Workplace Safety and Health Act and its Subsidiary Legislation made
thereunder are complied with
Employ a full-time Workplace Safety and Health Officer to comply with the requirements under the
Workplace Safety and Health Act, Workplace Safety and Health (Workplace Safety and Health
Officers) Regulations. The Workplace Safety and Health Officer shall implement appropriate safety
measures and ensure a safe work environment and safe work procedures in accordance with the
Workplace Safety and Health Act and Subsidiary Legislation including the provisions of the Workplace
Safety and Health (Construction) Regulations 2007 and the requirements specified under the
Contract.
1.24.1.3
Site Supervisors
The Contractor's Site Supervisors shall be qualified and competent, and possess the relevant skills,
knowledge and the ability to supervise and co-ordinate the Works; and with any one of the following
requirements:
(a)
Possess a National Certificate in Construction Supervision (NCCS) and at least 5 years of similar capacity
relevant working experience in the building construction industry
(b)
Possess a recognised Diploma in Architecture / Civil / Structural / Mechanical / Electrical Engineering,
Building Science, Building Management, Building Services Engineering, Construction Management and
at least 3 years of relevant working experience in the building construction industry
(c)
Possess a Degree (foreign university) in Architecture / Civil / Structural/ Mechanical / Electrical
Engineering, Building Services, Construction Management and at least 2 years of relevant working
experience in the local building construction industry
(d)
Relevant working experience of minimum 15 years working in past projects.
Notwithstanding the requirements as specified in (a) to (d) (inclusive) above, where the Contractor
is required to employ the Site Supervisor for mechanical/electrical Works, the Site Supervisor must
be suitably qualified under the mechanical/electrical engineering academic qualifications and with
the relevant work experience and also received adequate safety and health training to ensure that
the work which he oversees or supervises can be carried out safely.
1.24.1.4
Environmental Control Officer (ECO)
Employ an Environmental Control Officer (hereinafter referred to as "ECO" for the purposes of this
subclause) to comply with the Environmental Public Health Act Environmental Public Health
(Employment of Environmental Control Officers) Order 1999. The ECO shall be employed on a fulltime basis where the Contract Sum is above $50 million or on a part-time basis where the Contract
Sum is between $10 million and $50 million. The ECO shall be responsible for monitoring and
advising the Contractor on the following main areas:
(a)
Control of disease-bearing vectors and rodents.
(b)
Proper management and disposal of solid waste.
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(c)
Control of noise and dust pollution.
(d)
Drainage and silt control.
(e)
Air and water pollution control.
(f)
General housekeeping management of the project/Site.
The ECO shall conduct regular site checks and take prompt corrective actions to ensure that the
workers' quarters, toilets, site offices and other facilities and general surroundings of the Site are kept
clean, tidy and hygienic at all times. In addition, the ECO shall also ensure that the Site is kept
mosquito-free at all times.
The ECO shall possess a "Certificate of Competency (CoC) in Earth Control Measures (ECM) for
Construction Site Personnel". The ECO who is without "Certificate of Competency (CoC) in Earth
Control Measures (ECM) for Construction Site Personnel" shall attend the course conducted jointly
by PUB and IES (Institute of Engineers Singapore) and obtain it within 6 months upon his
employment at the site.
The ECO shall compile and submit environmental related data to the SO upon request. This data can
include:
(i)
Water, electricity and diesel consumption on site.
(ii)
Concrete wastage on site.
(iii)
Amount of construction debris generated on site.
The ECO shall also compile a record of any checks by the Authorities (e.g. NEA for noise and
vectors, PUB for ECM) and the result of such checks. This record shall also be submitted to SO upon
request.
If the Works have been certified more than 95% completed, the Contractor may write to NEAs
Regional Office to seek approval to allow the ECO to perform on a part-time basis and copied to SO.
There shall be no cost recovery from the Contractor if NEA is agreeable to allow the ECO to
perform on a part-time basis.
1.24.1.5
Security Guards
(a)
Employ Security Guards from a Security Agency licensed by the Singapore Police Force with a minimum
Grade of "C". Inform the SO in writing on the security agency which supplied the Security Guards, within
2 weeks from the commencement date of the Contract Period.
(b)
All Security Guards shall at all times be in proper uniform of their security agency with their names and
identification tags on. Essential security enforcement equipment such as whistle, torchlight, walkie-talkie,
shall be provided to them. They shall respond within 5 to 10 minutes whenever they are called either
through telephone or walkie-talkie. They shall also have the necessary access to the telephone at the
Contractor's site office during and after normal working hours for emergency reporting purpose. The
Security Guards must not be armed with weapons that are disallowed by the Singapore Police Force.
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1.24.1.6
(c)
A proper guard post with adequate security lighting and communication facilities shall be erected at every
major entrance to the Site. All temporary gates/openings along the
fencing/hoarding shall be guarded by a Security Guard during normal working hours and locked
up after normal working hours.
(d)
The Security Guards shall be responsible for the general security of the Site and shall ensure that
unauthorised personnel and vehicles do not enter the Site. They shall also be responsible for the security
of the Contractor and site offices during and after normal working hours.
(e)
The Security Guards shall be employed to perform site security duties on a 24-hour basis. A minimum
of one Security Guard shall be on duty at any one shift including Sundays and public holidays throughout
the Contract Period (including any extension thereof). No Security Guard shall leave the Site until he is
properly relieved by a replacement, even if his shift has ended.
(f)
A proper record of the Security Guards' attendance must be kept and made available to the SO upon
request.
Site Administrator
Employ [to be specified by user] full-time Site Administrator(s) at the site office to answer all in- coming
calls during office hours and to attend to the clerical works as and when directed by the SO. The Site
Administrator shall be proficient in basic software and equipped with good public relations skills and
able to handle phone enquiries competently.
1.24.1.7
Customer Relations Officer (CRO)
Deploy [to be specified by user] full-time Customer Relations Officer(s) (CRO) to manage the Building
Maintenance Team (BMT).
Notwithstanding other provisions in this clause, if the Contractor incurs additional costs and expenses
over and above the agreed rates specified herein complying with the requirements stipulated in this
clause, the Contractor alone shall bear such additional costs and expenses in full.
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1.24.2
Certified CONQUAS Personnel
Ensure that site personnel employed are recognised by Building and Construction Authority (BCA)
under the Certified CONQUAS Manager and Certified CONQUAS Supervisor Schemes.
To fulfil this requirement, the Contractor is allowed to have their existing site personnel recognised as
Certified CONQUAS Manager and Certified CONQUAS Supervisors in addition to their existing role.
S/N
Type of Personnel
Number of Each Type of
Personnel
to
be
Employed Based on
Contract Sum Value
Not
Exceeding
$50 Million
Exceeding
$50 Million
Fully Agreed and Accepted Rate by the
Contractor andthe Employer For Cost
andExpense Deemed to be Allowed
by the Contractor for the Employment
of Each Personnel
1
Certified CONQUAS
Manager
1
1
$ [to be specified by user]per Certified
CONQUAS Manager per month
2
Certified CONQUAS
Supervisor
1
2
$[to be specified by user]per Certified
CONQUAS Supervisor per month
The number of Certified CONQUAS Personnel are specified in the table above. The Contractor is
given up to 12 months from the commencement date to deploy such personnel upon approval from
the SO.
In the event that the site personnel employed do not have the required certification, the Contractor
shall employ personnel to fulfil the requirement, at its own cost and expenses. Upon their employment,
the Certified CONQUAS Personnel shall be full time on site throughout the construction period
including any period when liquidated damages are imposed under the Contract, unless otherwise
approved by the SO.
1.24.3
Replacement of Site Personnel
The SO shall be empowered to instruct the Contractor to replace at the Contractor's own cost and
expense, any site personnel not carrying out their duties to the satisfaction of the SO.
1.24.4
Compliance with Requirements and Submission of Information of Site Personnel
The employment of the site personnel shall be subject to the approval of the SO. Submit to the SO
within one month from the commencement of works, the name, identity card numbers and
documentary evidence of the educational qualifications and experience of all the site personnel
employed by the Contractor.
In addition, comply with the requirements and keep records and submit information to the SO or
Employer upon request to show compliance with the requirements.
(a)
Keep records indicating the number of days the site personnel are employed for each month.
(b)
Except for the security guards and safety supervisors, all the site personnel employed shall be on the
Contractor's monthly payroll. Keep records of monthly CPF or levy contributions as proof of
employment.
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1.24.5
Inclusion of Cost and Failure To Employ The Site Personnel
The Contractor shall be deemed to have included in the Contract Sum for all costs and
expenses it incurs in complying with the requirements stipulated in this clause.
In the event of the Contractor not employing the number of site personnel, required by the Contract or
not employing such site personnel for the period or periods required by the Contract, without prejudice
to the Employer's rights under the Contract, the Contractor shall be indebted to the Employer at the rate
or rates as specified for each of the respective site personnel per month and such indebtedness shall
be deducted by the Employer from any monies due or becoming due to the Contractor or be recovered
by the Employer as a debt due from the Contractor. These rate or rates shall be deemed to have been
fully agreed and accepted by the Contractor and the Employer as the costs and expenses allowed by
the Contractor for the employment of each of the respective site personnel for each month.
For the purpose of this clause, each of the site personnel shall be employed by the Contractor for at
least 20 days within a calendar month before he can be considered as being employed for that particular
month under the Contract, except where expressly specified otherwise. In the event that the first
and/or the last calendar month of the Contract Period or any period when liquidated damages are
imposed under the Contract, have less than 20 days, each of the site personnel shall be employed for
the full number of days in the said first and last calendar month of the Contract Period or any period
when liquidated damages are imposed under the Contract.
In the event that the deployment of the site personnel fails to comply with the requirements, the cost
recovery for the period of non-deployment shall be based on the stipulated monthly rates on pro-rated
basis.
Notwithstanding other provisions in this clause, if the Contractor incurs additional costs and expenses
over and above the agreed rates specified herein in complying with the requirements stipulated in this
clause, the Contractor alone shall bear such additional costs and expenses in full.
1.24.6
Application for Release of Site Personnel
The SO may consider a request by the Contractor in writing to release any of its site personnel from the
obligations of this clause if the Works has been certified more than 95% complete. It shall be up to the
absolute discretion of the SO to decide whether the Contractor's site personnel can be released and
the number of site personnel to be released as provided for under this clause. A written approval from
the SO shall be obtained in this respect.
1.24.7
Superintending Officer's Decision
All differences and/or disputes arising under this clause including all subclauses under it (including
questions relating to interpretation) shall be determined by the SO whose decision shall be final and
binding.
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1.25
Service Roads, Driveways and Drains
For completed service roads, driveways and drains within the Site contract boundary, the Contractor
is obliged to maintain washing and cleaning; and making good any damage arising from their own
actions to the satisfaction of the SO all at the Contractor's cost and expense. If the Contractor fails to
carry out his obligations as aforesaid, the SO may engage other parties to execute the outstanding
works and all costs and expenses incurred shall be borne by the Contractor.
1.26
Existing Services and Cables/Services Detection
Visit and examine the Site carefully and ascertain its nature and make provision in the Contract Sum or
prices for the type of ground conditions, constraints and underground services.
Take due care to safeguard all existing services that will be affected by the Works. Where existing
services are required to be terminated or diverted for the execution of the Works, give the necessary
notices to the Authority and the Employer. Co-ordinate site survey to identify the existing services and
arrange for the Works to be carried out.
Where in the case the SO is of the opinion that it becomes essential to divert permanently any sewer,
drain, pipe, cable, or other services, the cost for the diversion shall be borne by the Employer.
Provided always that such diversion does not form part of the Works.
1.26.1
Statutory Requirements
Comply with all the requirements of the various Authorities in respect of the existing services at and
around the vicinity of the Site, whether underground, on or above ground, or at the site peripherals.
Terminate or divert all relevant existing services as required by the Authorities before work begins.
1.26.2
Information on Services
Obtain information in relation to existing services from the relevant Service Providers.
Verify actual sizes and locations of all services with the Public and Statutory Authorities and make
enquiries as to the presence and location of any privately-owned land drains and services. Locate,
identify and mark on site before commencing work.
Arrange with and offer the Authorities all necessary assistance in ensuring timely diversion,
disconnection, termination, or capping off of the services.
(a)
Detection of services located on site.
(b)
Locate and mark the positions of services affected by the Works.
(c)
Conduct detection of suspected underground services. Propose suitable method for acceptance by the
SO.
(d)
Mark underground services with signboards giving type and depth and inform the Authorities concerned of
any such services encountered on site.
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1.26.3
Drains in Use
Protect drains, manholes, gullies, vent pipes and fittings still in use and ensure that they are kept free
of debris at all times. Make good any damage arising from the Works and leave clean and in working
order at completion.
1.26.4
Bypass Connections
Provide as necessary to maintain continuity of services to occupied areas of the Site and adjoining
properties. Give sufficient notice to occupiers if shutdown is necessary during changeover.
1.26.5
Services to Remain
Notify the SO and the Authorities or Employer of any damage. Make all arrangements for repair to the
satisfaction of the SO, the Authorities or Employer.
1.26.6
Cable/Services Detection
Provide cables/services detecting devices to locate all existing cables/services prior to the
commencement of excavation or any other work such as driving of piles, piling of earth electrode and
lightning conductors or poles and columns which are liable to damage existing buried services. Engage
EMA licensed cables/services detection workers to carry out all cables/services detection work. The
proposed line of excavation or area of other work shall be checked for existing services in a systematic
manner by making sufficient passes in a grid formation to cover the entire area of work.
The extent of checking carried out shall be properly documented and countersigned by the SO. The
Contractor shall be liable for all costs and charges incurred if he damages any services.
Seek assistance from the relevant Authorities if it has any query on the location of existing
cables/services belonging to the Government Department or Statutory Board. In the case of PowerGrid
or SPSL cables/services, the Contractor may seek assistance from the Cable Damage Prevention
Unit, PowerGrid or SPSL.
Engage the services of EMA Registered Excavator Operator only for all excavation Works. In the
event the Contractor fails to employ EMA Registered Excavator Operator, no excavation works
shall be allowed.
1.27
Damage to Public/Private Property
In the event damage is caused to public/private services or property such as cables, pipes, fittings
and fixtures, etc. by the Contractor whether by accident or otherwise leading to black- outs or other
nuisance or inconvenience to the public or is likely to bring the Employer into disrepute, all costs and
expenses incurred for necessary reinstatement or repairs including charges shall be recoverable by the
Employer from the Contractor by deduction from monies due or becoming due to the Contractor, or as
a debt due by the Contractor to the Employer.
1.28
General Housekeeping
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(a)
Periodic Cleaning Up
All rubbish and debris shall be cleared from the Site and buildings under construction at least weekly
or from time to time as they accumulate or when so directed by the SO. Particular attention shall be
directed to those areas where other tradesmen or contractors will be working. Housekeeping shall be
carried out in such manner and at such times so as not to cause any inconvenience to either the
adjoining owners, occupiers and the public. Debris shall be wet to minimise the risk of dust pollution
(b)
Provision of Bins for Waste and Debris
During the course of construction, provide proper bulk bins of adequate size and appropriate locations
for the proper storage of construction waste, chemical waste and debris in compliance with the relevant
legislative requirements or regulations imposed by MEWR.
(c)
Dumping of Debris And Rubbish
Dispose of all unwanted debris, rubble or excess earth at MEWR approved dumping grounds/sites.
All charges levied for the use of the dumping grounds/sites shall be borne by the Contractor.
If the Contractor indiscriminately dumps construction debris, rubble or excess earth on land owned by
the Employer or the Government without written permission, it shall remove all such debris, rubble, or
excess earth from such land at its own cost and expense.
1.29
Time Required for Contractor to Prepare for Project Handover Inspection
Complete the Works or any phase or sub-phase thereof as set out in the Letter of Acceptance in
accordance to the Contract Period or any subsequent extensions of time approved by the SO.
All completed Works or any phase or sub-phase thereof shall be handed over to the Employer within or
by the Contract Period or any subsequent extensions of time approved by the SO, prior to the issue of
any Completion Certificate.
Note that the Contract Period has been computed to include the time allowed for preparation of handing
over inspections. Therefore, the duration required for the preparation of and the handing over
inspections shall be incorporated into the Programme for the Works or revised Programme, if any, to
be submitted to the SO for approval, as required under the Contract.
1.30
Restriction on Use of Project Information for Publicity
The Contractor and its subcontractors/suppliers shall not quote or make reference to the project design,
products, technologies or methods of construction used in the Works for trade promotion,
advertisement, publicity, etc. or for any other purposes without the written approval of the SO. This
requirement shall not be applicable to proprietary products, technologies or methods of construction
introduced by the Contractor or its subcontractors/suppliers.
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1.31
Provision of Respiratory Masks
Building contractors are required to provide suitable respirators for their outdoor workers, as well as the
supervising consultants' site staff at the sites, when the haze level at the Site reaches a very
unhealthy level with a 24-hour Pollutant Standards Index (PSI) value measured by NEA exceeding
200 or upon appropriate public advisories by NEA.
The air-purifying respirators must have an efficiency to filter 95% of 0.3 micron diameter fine particle
size, commonly referred to as N95.
Start to purchase and stock up the N95 respiratory masks when the haze condition is approaching the
unhealthy range with the PSI Index value exceeding 100.
1.32
Publicity
Provide and render all necessary assistance to the SO or other authorised persons procuring publicity
materials on any aspects of the construction works in progress. When directed by the SO, provide all
brochures, quotations, subcontract agreements, invoices, etc., from its subcontractors, suppliers and
specialists for goods and services provided for the Works, all at the Contractor's cost and expense.
1.33
Handover Inspection
(a)
(b)
Notify the SO in advance to request for a handing over inspection and the following functional tests,
where relevant. The extent of testing shall be agreed on with the SO.
S/N
Type of Test
1
Chokage Test for Main and Secondary Stack Pipe
2
Chokage Test for Rainwater Down Pipes and Down Pipes
3
Chokage Test for Branch Pipes Serving Units on Lowest Floor
4
Chokage Test for Branch Pipes Serving Units on Typical Floor
5
Leakage Test for Refuse Chute Flushing System
6
Water Pipe Pressure for Concealed Pipes
7
Gradient Test for House Drains
8
Gradient Test for House Sewer Lines
9
Gradient Test for Main Roof, Pump Room Roof, Staircase Roof, Lift Machine Room Roof
10
Gradient Test for Scupper Drains and Wash Area
11
Water Test for Toilet, Kitchen, Service Yard and Private Balcony
12
Water tightness Test for Window/Wall Joints
13
Water tightness Test for Precast Wall Joints
Upon receipt of the Contractors request, the SO shall arrange a joint inspection date with the Employer.
The Employer shall be present to witness the functional tests. In the event the tests fail to meet the
requirements of the Contract, proceed to rectify the defect with due diligence and expedition and without
delay, and arrange for re-tests in accordance with the requirements under the Contract.
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(c)
If the Works are considered to have met the requirements of the Contract, including the approved
workmanship standards, and there is no major defect detected during the handover inspection, the
Works shall then be taken over by the Employer. Otherwise, the SO shall give the Contractor a list of
outstanding defects for rectification. The Contractor shall proceed to rectify the defects with due diligence
and expedition and without delay. The Contractors liability to rectify the defects under this Subclause shall
not be limited to the list of defects given by the SO, but shall include all other defects surfaced in
between the handing over inspections. Upon completion of the defect rectification, the Contractor shall
notify the SO in writing that all outstanding defects found in the inspection, as well as all apparent defects
identified between the handover inspections have been rectified and shall request another handing over
inspection. The provision of the preceding Subclause (b) above shall apply, mutatis mutandis.
(d)
If the Contractor is unable to hand over the Works to the Employer after 2 handing-over inspections, the
SO shall invoke the provisions of the Clause 6 on "Nuisance and Irregularities".
(e)
The Contractor shall clean all parts of the project thoroughly. If the cleanliness of an area is not satisfactory
before handing over to the Employer, the Contractor shall do repeat cleaning of the area at the
Contractors own cost and expense.
(f)
The Contractor shall, before Completion of the Works, remove all rubbish, construction equipment and
surplus materials, wash and scrub clean all floors, staircases, pavings, drains and all parts of the
buildings and leave the Works in a clean and hygienic condition fit for habitation. The Site and periphery
shall be cleared of all rubbish left from the Contractor's work.
1.34
Defects Management
1.34.1
Employment and Deployment of Site Supervisor
Employ and deploy [to be specified by user] Site Supervisors full- time on the Site for every day where
defect rectification works are carried out during the Maintenance/Defects Liability Period.
For defects reported, deploy a full-time Site Supervisor to manage and complete the rectification
works within 14 calendar days. In the event that Contractor is unable to meet the service standards of
14 calendar days, the Contractor is required to increase the number of Site Supervisors to eliminate
the delay. All cost and expense arising from the additional manpower/resources deployed is deemed
to have been included in the Contract. In addition, the Employer may exercise the provisions of Clause
6 "Nuisance and Irregularities" to address the unsatisfactory works.
The Contractor's Site Supervisor shall be qualified and competent, and possess the relevant skills,
knowledge and the ability to co-ordinate and supervise the defect investigation and rectification works.
The Site Supervisor deployed to handle defects reported to Building Maintenance Team must be able
to communicate with neighbours effectively. The Site Supervisor shall attend inspections together with
the neighbours to better understand their requests and/or feedback, monitor the defect rectification to
ensure timely completion of the rectification works, and attend the handover inspection together with the
neighbours. The Site Supervisor is also required to conduct surveillance checks on the lift operation,
illegal dumping and any other duties related to the project as instructed by SO.
The Site Supervisor shall possess one of the following academic qualifications and experience:
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(a)
National Certificate in Construction Supervision (NCCS) and at least 5 years of similar capacity relevant
working experience in the building construction industry.
(b)
Recognised Diploma in Civil/Structural/Mechanical/Electrical Engineering, Building Science, Building
Management, Building Services Engineering and at least 3 years of relevant working experience in the
building construction industry.
The SO shall be empowered to instruct the Contractor to replace, at the Contractor's own cost and
expense, any Site Supervisors not carrying out their duties to the satisfaction of the SO. In the event
of the Contractor not employing the number of Site Supervisors required by the Contract or not
employing such Site Supervisors for the period or periods required by the Contract, without prejudice
to the Employer's rights under the Contract, the Contractor shall be
indebted to the Employer at the rate of $ [to be specified by user] per month per Site Supervisor not
deployed and such indebtedness shall be deducted by the Employer from any monies due or
becoming due to the Contractor or be recovered by the Employer as a debt from the Contractor. This
rate shall be deemed to have been fully agreed and accepted by the Contractor and the Employer as
the cost and expense allowed by the Contractor for the deployment of a Site Supervisor.
For the purpose of this clause, a Site Supervisor shall be deployed by the Contractor for at least 20 days
within a calendar month before the supervisor can be considered as being employed for that particular
month under the Contract, except where expressly specified otherwise. In the event that the first and/or
the last calendar month of the BMT operating period or any period when liquidated damages are
imposed under the Contract, have less than 20 days, each of the Site Supervisors shall be deployed
for the full number of days in the said first and last calendar month of the BMT operating period or any
period when liquidated damages are imposed under the Contract.
Notwithstanding other provisions in this subclause, if the Contractor incurs additional cost and expense
over and above the agreed rate specified herein in complying with the requirements stipulated in this
subclause, the Contractor alone shall bear such additional cost and expense in full.
On expiry of the Defects Liability Period, the Contractor may submit a written request to the SO for the
release of the Site Supervisor. A written approval from the SO shall be obtained with this request.
1.34.2
Timeframe for Defects Management
Ensure that an operationally ready Building Management Team (BMT) is set up in a timely manner.
The defects and feedback reported can be through:
(a)
Physical BMT on site which is 12 months subjected to extension by the Employer.
(b)
Virtual BMT, which is an online version of BMT.
(c)
Any emails/instructions from Employer and SO.
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Unless otherwise instructed by the SO, the BMT operating hours during the physical BMT stage shall
be: Mondays to Saturdays: 8.30am to 5.30pm (except Sundays and Public Holidays).
Whichever channel that is provided for feedback, attend to them for a period of [to be specified by
user] months from the Completion Certificate.
The personnel employed by the Contractor to manage the virtual BMT subsequently after the physical
BMT has ceased must also possess the skill, knowledge and ability as specified in the "Employment of
Customer Relations Officer". The service level during the virtual and physical BMT shall remain the
same.
At the Contractors own cost and expense, provide uniforms for all site personnel, including
subcontractors and suppliers, etc deployed to carry out defects rectification works reported to BMT. The
design of the uniform shall be submitted to the SO for approval at least 4 weeks before the BMT
commences operation.
1.34.3
Provision of BMT Office
Liaise with the SO for a suitable location within the Site to host the BMT for at least 2 months before
the estimated completion date. The minimum size of BMTs Office is [to be specified by user] m2 and
shall comfortably accommodate a waiting area for visitors, working space for Contractors Staff,
Registered Technical Officer and Employers Representatives, office furniture/equipment and materials
sample display area. Use materials that are non-combustible and water-resistant properties to enclose
the BMTs Office. Provision of metal gate in front of the aluminium framed glass door is required. The
plan layout of the items such as furniture, equipment within the BMTs Office shall be submitted to
Employer for comments before setting up.
The BMTs Office shall be equipped with:
- an air-conditioning system: To provide thermal comfort for the occupants
- a personal computer: Based on current Specification for "Computer Hardware And Software" for the visitors to
make e-appointment
- Two (minimum) office desks: including lockable drawers
- steel cabinet of size: 1.7 m x 0.8 m x 0.4 m, including shelves and double-leave doors
- a printer (capable to print up to A3 size)
- a colour scanner
- a photo stating machine
- a fax machine, telephone
- an auto-message and voice recording machine with 120-hour recording time
- adequate fluorescent lighting
- a digital camera
- torch lights
- chairs
- aluminium suggestion box of size: 0.3 m x 0.3 m
- soft board and white board of size: Size 2.4m x 1.2m, including accessories
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- hot and cold drinking water dispenser
- drawing rack: complete with drawing holders and office stationary
- sofa at waiting area
- vinyl flooring
- area to display material samples (e.g., tiles, parquet flooring, water closet, wash basin, shower mixer and shower
assembly, basin mixer, bib tap, electrical sockets and switches).
Provide and install a signboard of minimum size: 1.4 m x 1.0 m, before starting the operation of the
BMT. The design of the signboard shall be submitted to the SO for approval.
Provide and install 2 notice boards at the BMTs Office. Each notice board shall be of size: 1.8 m x 1.2
m with aluminium casing and aluminium frame door in-filled with 5mm thick clear polycarbonate sheet.
1.34.4
Information on Key Personnel
Within 14 days from the Date of Completion of the first building block and/or first phase of Works,
submit the following to the SO for approval:
(a)
Name and contact numbers of the Contractor's key management staff and the appointed Site
Supervisors for defect investigation and rectification works within the Defects Liability Period
(b)
Name and contact numbers of the relevant manufacturers, suppliers and specialist contractors etc.
(c)
Name and contact numbers of the stand-by plumber and stand-by electrician
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1.34.5
Defects Investigation and Rectification During Building Maintenance Team Operation
Within `14 calendar days from the date the access to the area is granted by Employer and/or upon
SOs instruction and/or written notification by the SO, at the Contractor's own cost and expense,
investigate, repair, rectify and make good to the satisfaction of the SO all defects, imperfections,
shrinkages and other faults arising from or out of the use of materials or workmanship not in
accordance with the Contract or from neglect or failure (of the Contractor) to comply with any
obligation on its part under the Contract which may become manifest.
Propose and implement a Quality Management System for defects rectification to ensure that the
reported defects are rectified within 14 calendar days. The Quality Management System shall be
submitted to the SO for approval.
Prior to the commencement of any defect rectification works, submit a schedule of repair and method
statement for the approval of the SO. Mobilise only skilled and certified workers who are capable of
executing the works in accordance with the method statement as approved by the SO. All works
must be attended to and supervised in person by the appointed Site Supervisor.
Dust and noise must be minimised, whenever possible and cleaning up must be carried out daily if the
unit is occupied and/or after the repairs. Inconvenience caused to others should be minimised by
completing the defect rectification works in the shortest possible time.
If there is failure by the Contractor to carry out its obligations as aforesaid, the SO may invoke the
relevant provisions of Clause 6 "Nuisance and Irregularities".
Without prejudice to the foregoing provisions, the SO shall have the right to engage other persons or
contractors to repair, rectify and make good all such defect, imperfections, shrinkages and other faults
if the same are not repaired, rectified and made good within 14 calendar days from the date the
access to the unit is granted by resident and/or upon the SOs instruction and/or written notification by
the SO, and the cost and expense incurred shall be recovered from the Contractor. In addition, the SO
may invoke the relevant provisions of Clause 6 "Nuisance and Irregularities".
1.34.6
Rectification of Defects Prior to Issuance of Final Completion Certificate
For the purpose of certifying completion of defect rectification prior to the issuance of the Final
Completion Certificate, one month before the expiry date of the Defects Liability Period, arrange with
SO for a final joint inspection. All defects listed after this joint inspection shall be rectified by the end of
the succeeding one month commencing from the expiry date of the Defects Liability Period. A
second final joint inspection shall be arranged to verify the completion of defects rectification.
If the Contractor fails to rectify and make good the defects on the second final joint inspection, the SO
may invoke the relevant provisions of the clause on "Nuisance and Irregularities".
Notwithstanding the above, the SO shall in addition have the right to engage workmen or other
contractors to rectify and make good all defects and the cost of rectification and charges imposed shall
be recovered from the Contractor.
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1.34.7
Standby Plumber and Electrician for Restoring Essential Services
Provide a stand-by plumber and a stand-by electrician for 24-hour stand-by duties every day, including
Sundays and Public Holidays, throughout the Defects Liability Period. The plumber and electrician
need not be stationed on the Site but would be called upon to rectify defects causing disruption to
essential supply such as water and electricity.
The Contractor or its representatives shall be contactable 24 hours a day, for every day, including
Sundays and Public Holidays throughout the Defects Liability Period by means of telephone, mobile
phone, radio pager, facsimile or any other suitable modes of communication.
The stand-by plumber and/or stand-by electrician shall attend to such defects within an agreed time
with the SO for their services is made. They shall carry out the rectification expeditiously and in a
workmanlike manner to restore the essential services quickly to minimise any inconveniences to the
residents. In the event that the stand-by plumber and/or stand-by electrician fails to attend or fails to
attend within the time frame stipulated, the SO may exercise the relevant provisions of the clause on
"Nuisance and Irregularities".
1.34.8
Protection to Lift Interior During Defect Liability Period
Provide protection to all interior finishes of lift car using an approved material, to protect the lift car walls,
top of the lift car and the lift car base. Handrail protection shall be made of cloth tape or other durable
protection cover approved by the SO.
Check and maintain the condition of the protection to the interior of the lift car regularly. In the event that
the protection is found to be not in good condition, replace and make good such protection at its own
cost and expense.
Seek the SO approval before the removal of lift car protection. If the Contractor fails to rectify and
make good any defects, the Employer reserves the right to exercise its rights under Clause 6 on
"Nuisance and Irregularities".
1.35
Precautionary Measures to Be Taken during a Disease Pandemic
Implement necessary precautionary measures as advised by Ministry of Health or other relevant
Authorities during a disease pandemic. Based on the recommendations from government's advisory,
provide full cooperation and follow up expeditiously to plan for such a contingency and stock up
necessary supplies or equipment (e.g., thermometers) so as to be able to implement the required
measures at short notice.
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1.36
Works Within Railway Protection Zone And Railway Safety Zone
Comply with the Land Transport Authority (LTA) Code of Practice for Railway Protection and the Mass
Rapid Transit (Rail Protection, Restricted Activities) Regulations for construction of the Works and
other activities within the railway protection zone and railway safety zone.
Submit proposals to the SO for approval on the effective measures for the protection of MRT above
ground structures together with details of activities of mobile cranes, tower cranes and other mechanical
equipment adjacent to the MRT line structures. Such submissions shall be made at least one month
prior to the use of such construction equipment. No jib or lifting appliance or any other moving or
stationary part of the mechanical construction equipment shall encroach within 6.0 m on plan from the
edge of the nearest MRT above-ground or at-grade structure unless the construction equipment is
restricted to work beneath the structure. The foundation of the mechanical construction equipment shall
be certified structurally sound and adequate by the Contractor's PE prior to its installation.
Install an auto cut-off system on tower cranes to prevent the top of the boom from swinging closer than
6.0 m from edge of the viaduct structure. The jibs of the cranes must always be pointed away from the
MRT line structure. Any temporary access shall be sufficiently stable and level for construction
equipment travel. Carry out regular checks to ensure that all mechanised construction equipment is in
good working condition at all times. Employ only experienced, trained and competent operators for the
operation of mobile cranes, tower cranes and other mechanical equipment. Install temporary height
restriction gantries with signboard 6.0 m away from the edge of both sides of the viaduct structure for
any access passing underneath the MRT line structures.
1.37
Recovery of Legal Costs for Court Proceedings
All legal costs, charges and expenses (including but not limited to solicitors' fees as between solicitor
and client) incurred by the Employer for the purpose of, or incidental to, the enforcement by the
Employer of any rights and remedies under the Contract, or any other contracts between the Employer
and the Contractor or in respect of any garnishee proceedings which may be brought or commenced
against the Employer by the Contractor's creditors, may be deducted by the Employer from monies due
or becoming due to the Contractor including any retention monies, financial bonds, or security deposits,
or other bonds.
1.38
Completion of Site Works
Take note that site works refers to all site structures/facilities, such as, but not limited to, driveway, car
park, guard house, childrens playground/hard courts/footpaths and landscaping works, such as earth
mound formation, turfing, trees and shrubs planting where included in the Works.
Plan the stages of site works to be completed and submit to the SO for approval.
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1.39
Erection of Temporary Buildings
In addition to the submission of the site layout plan, further submit detailed structural plans and design
calculations, certified by the Contractors PE, for temporary buildings of 2 storeys or higher, to the SO not
later than 3 months from the commencement date of the Contract Period or 2 weeks before the actual
commencement of the Works for such proposals, whichever is earlier. Bear all consequences for late
submission.
Erect all such temporary buildings in strict compliance with its PEs plans and calculations. The works
shall be supervised by the Contractor's PE.
Not later than 2 weeks after the completion of the Works, the Contractor's PE shall submit a Certificate
of Supervision, stating that it has carried out such supervision work and is fully satisfied that the works
have been constructed in accordance with its structural plans and design calculations as approved by
the SO.
1.40
Goods and Services Tax
Do not include in the rates and prices quoted in the Contract Sum, the GST chargeable for the supply
of goods, services or Works required in the Contract. All rates and prices quoted shall be exclusive of
the GST.
The Employer shall reimburse the Contractor any GST charged on the goods, services or Works
supplied.
The Contractor shall declare its GST status in its Tender. The Contractor shall clearly indicate whether
it is, or whether it will be, a taxable person under the GST Act. The Contractor shall, if available, furnish
the GST registration number to the Employer.
The Contractor will be deemed to be a taxable person if no declaration to the contrary is made in the
Form of Tender. A Contractor that declares itself to be a non-taxable person under the GST Act but
that becomes a taxable person after it has been awarded the contract shall forthwith inform the
Employer of its change in GST status. The Contractor shall be entitled to reimbursement by the
Employer of any GST charged on the goods, services or Works it supplies after its change in GST
status.
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1.41
Works and Materials Warranty
In every case where the Specification require the Contractor's Specialist to co-warrant the Works
and/or materials to be executed or supplied under the Contract, such Specialist, subject to such other
requirements as may be prescribed in the Specification, may only be employed by the Contractor with
the Employer's prior written approval. The Employer will approve such employment if the Specialist
gives his written undertaking to execute the Deed of Warranty prescribed in the Specification. If such
written undertaking is not given, then appoint an alternative Specialist willing to give the written
undertaking. The employment of any Specialist who refuses to give its written undertaking is not
recognised by the Employer, and no Specialist may commence any work or supply any materials
before its written undertaking is given.
The Employer's prior written approval of such Specialist's employment shall not in any way affect or
diminish the Contractor's contractual obligations to the Employer in respect of any Works or materials
executed or supplied by such Specialist on behalf of the Contractor, and the provisions of this subclause
shall not in any way affect or diminish the Employer's entitlement to withhold the payment of any sums
due to the Contractor by reason of the Contractor's and/or Specialist's failure to execute and submit
the Deed of Warranty within the time specified.
1.42
Cost of Water and Electricity
Provide suitable and adequate supply of water and electricity for the Site including for the purposes of
conducting tests on the Works. Where directed by the SO, provide and allow other contractors on the
Site employed by the Employer, free and unrestricted use of the water and electricity for carrying out
testing and commissioning of such other contractors' works. Bear all costs and expenses for the water
and electricity consumed at the Site, including the cost of water and electricity consumed for carrying
out testing and commissioning by such other contractors employed by the Employer on the Site.
Where applicable, the SO may at his/her sole discretion, direct the Contractor to transfer the account
for the water and electricity supply to the Employer or such Management Corporation or such other
party. The Contractor shall be deemed to have included in the Contract Sum for all costs and expenses
incurred in complying with the requirements stipulated in this Subclause.
1.43
Site Control and Security
1.43.1
Identification Pass
Provide a serially-numbered security identification pass to each of its workers and subcontractors'
workers. The identification pass shall consist of the worker's photograph, name, identification card
number or passport number and name of the Contractor. Issue temporary entry passes, on a day to
day basis, to workers from other contractors employed by the Employer or other Government/Statutory
Board Authorities or other companies carrying out works on the Site.
Be responsible for controlling and issuing these security identification passes and temporary entry
passes. Maintain an updated list of the passes issued for accountability and to facilitate enforcement
checks. Ensure that all workers on the Site wear and display their passes prominently and securely at
all times while working on site.
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1.43.2
Erection and Removal of Temporary Metal Hoarding
Unless otherwise specified, provide, erect and maintain a continuous metal hoarding around the
entire contract boundary before the commencement of Works. The hoardings shall be erected at
not less than 300 mm away from any permanent structure such as footway, drain, pipeline, etc.
Refer to the drawings for the location and type of hoardings to be used. Should there be failure to
comply with this requirement, the SO reserves the right to impose any action deemed necessary
and any cost and expense incurred thereof, including charges that shall be recoverable from the
Contractor.
As and when instructed by the SO, remove, relocate, reconstruct all or part of the hoardings and
reinstate all the affected grounds to the satisfaction of the SO, all at the cost and expense of the
Contractor.
Submit a complete set of workshop drawings to be endorsed by its PE and approved by the SO.
Provide metal gates/doors for the main and side entrances. Location of these entrances shall be
approved by the SO. There shall be a maximum of 2 entry points for the entire Site, unless otherwise
approved by the SO. Close the metal gate at the main entrance (for vehicular traffic) and lock up after
working hours when construction activities have stopped. Provide a side entrance beside the main gate
for passage of workers and visitors that can be monitored by the Security Officers. These
entrances/gates and the perimeter shall be well-lit during the hours of darkness (7.00 pm to 7.00 am).
(a)
(b)
Comply with the following minimum requirements for the flat panel hoardings:
(i)
Use a minimum of 0.60 mm thick steel with zinc/aluminium alloy coating for the metal hoardings.
All exposed metal sheet surfaces of the metal hoardings shall be finished with paint coating.
(ii)
The full height of the hoardings shall be 6 m, the hoardings comprising an overhang roofing
that has a vertical height of 1 m. There shall be no use of netting.
(iii)
Use corrugated panel for the overhang roofing.
(iv)
There shall be no struts at the exterior of the hoardings where it is visible to the public.
(v)
The colour for the flat/corrugated panel hoardings and the overhang roofing shall either be white
or off-white.
Comply with the following minimum requirements for the corrugated panel hoardings:
(i)
Use a minimum of 0.42 mm thick steel with zinc/aluminium alloy coating for the metal hoarding.
All exposed metal sheet surfaces of the metal hoardings shall be finished with paint coating.
(ii)
The full height of the hoardings shall be 4 m with no overhang roofing and no netting (as shown
in the drawings).
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(iii)
The colour for the flat/corrugated panel hoardings and the overhang roofing shall either be white
or off-white.
Use timber posts and horizontal bracings of common grade timber under strength group A of SS CP 7
and/or steel members of grade S275.
Use a minimum of grade 30 concrete foundations.
"DANGER - KEEP OUT", "NO TRESPASSING" and "WORK IN PROGRESS" signs in 4 official
languages shall be displayed on the exterior side of the hoardings. Print these signs using the
template provided. Mount the signs only on the corrugated hoardings where required and not on the
flat panel hoardings. The size of these signboards is specified in the drawings.
The position of the lightings is critical in achieving a professional look and feel for the entire project. Do
not install the lightings (LED light fixtures) on the design panel this prevents covering the messages or
community photos on the hoardings design panels. Locate the lightings above the design panel
instead. Ensure that the hoardings erected are illuminated adequately to achieve a maintained
illuminance of average 10 lux, or as otherwise instructed by SO.
Maintain the hoardings and gates at all times to ensure no deterioration of the structures and fading of
the paint works throughout the Contract Period (including any extension thereof).
On satisfactory Completion of the Works, clear the hoardings away upon the approval of the SO.
1.44
Registered Trade Subcontractors
At the time of tender, submit the list of subcontractors intended to be engaged for the Works. Submit
with the list, with details such as the relevant track records of the firms, the qualification of personnel
and details of equipment to be engaged for the Works. All subcontractors for the Works are subject to
the SOs acceptance.
Ensure that the Contractors appointed first-level subcontractors have valid Building and Construction
Authority (BCA) or Ministry of Finance (MOF) registration at the time of appointment. If the appointed
first-level subcontractor is registered with BCA, ensure that the appointed first-level subcontractor is
registered under the appropriate BCA workhead.
At least 14 days before commencement of the Works by the subcontractors for the respective trades,
confirm the name of its subcontractors for the Works to the SO. In the event that there are changes to
any of the Contractors subcontractors, submit such information to the SO.
The Contractor shall be responsible for any eventual delay in the progress of the Works owing to its
failure to ensure the required on-time registration of its subcontractors and no extension to the Contract
Period shall be granted on account of such delays.
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1.45
Engagement of Bizsafe Level Certified Subcontractors
All subcontractors engaged by the Contractor shall possess a valid bizSAFE Level [to be specified
by user] Certificate awarded by the Workplace Safety and Health Council. Ensure that all
subcontractors possess a valid certification throughout the entire period which they are engaged to
carry out works on site.
At the point of engagement, if any of the subcontractors have not attained the aforesaid certification,
seek written approval from the SO for their engagement, provided that the Contractor gives a written
undertaking to the SO that the subcontractor shall attain the aforesaid certification within 6 months or
before work commencement on site, whichever is earlier.
The SO may invoke the provisions of Clause 6 "Nuisance and Irregularities" if they fail to meet the
above requirement.
1.46
Insurance Policies
The Contractor shall warrant that the insurance policies issued in accordance with the Conditions of
Contract include the following requirements:
(a)
(b)
Insurance for Work Injury Compensation
(i)
The Policy shall be issued in a prescribed form as agreed with the Employer.
(ii)
The Insured shall be "(Name of Contractor to insert) as Contractor and all its
subcontractors, and the Employer as Principal FTRR & I".
(iii)
The period of insurance shall commence from the date the Site is handed over to the
Contractor and shall end upon expiry of the Defects Liability Period under the Contract.
The Policy shall firstly cover the whole of the original Contract Period plus 6 months and
plus a further 12 months for Defects Liability Period.
Insurance for Personal Injury and Property Damage
(i)
The Policy shall be issued in the joint names of the Employer, the Contractor and all its
subcontractors.
(ii)
The limits of liability shall be read as follows:
(iii)
(a)
In respect of any one accident: $ [to be specified by user]
(b)
Unlimited for the period of insurance
The period of insurance shall commence from the date the Site is handed over to the
Contractor and shall end upon expiry of the Defects Liability Period under the Contract.
The Policy shall firstly cover the whole of the original Contract Period plus 6 months and
plus a further 12 months for Defects Liability Period.
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(iv)
The period of notice for cancellation of the Policy, if such a period is stipulated, shall read
30 days.
(v)
The Policy shall expressly include coverage of the following risks:
(vi)
(a)
Death, bodily injury or damage to property caused or occasioned by the Insured's
subcontractors or by such subcontractors' employees.
(b)
Death, bodily injury or damage to property caused or occasioned by or connected with or
arising from the ownership, possession or use by or on behalf of the Insured of any
equipment or machinery not expressly specified in the Schedule of such equipment or
machinery.
(c)
Liability assumed by the Insured by agreement, unless such liability would have
attached to the Insured notwithstanding such agreement.
(d)
Liability in respect of loss or damage to property belonging to or in the charge or control
of the Insured or of any servant or agent of the Insured.
(e)
Liability in respect of injury to or illness of any person or loss or damage to any property
or land or building caused by vibration or removal or weakening of support
(f)
Liability in respect of injury, illness, loss or damage caused by or connected with or
arising from any commodity, article or thing supplied, repaired, altered or treated by or to
the order of the Insured, happening at any of the Insured's premises.
The Policy shall expressly contain the following endorsements:
(a)
"This Policy shall cover all the Contractor's insurance obligations with regard to personal
injuries or death and injury or damage to property real or personal (including property of
the Employer but not the Works themselves) arising out of or in the course of or by
reasons of the carrying out of the Works stated in the Contract between the Employer
and the Contractor (name of Contractor to insert)."
(b)
"Each of the parties comprising the Insured shall for the purpose of this Policy be
considered as a separate and distinct unit and the words "the Insured" shall be
considered as applying to such party in the same manner as if a separate policy had
been issued to each of the parties and the insurers hereby agree to waive all rights of
subrogation action which they may have or acquire against any of the aforesaid
parties arising out of any accident in respect of which any claim is made hereunder
provided nevertheless that nothing in this clause shall be deemed to increase the
limitation on extent of Insurer's liability in respect of any one accident or series of
accidents as stated in the Schedule."
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(c)
1.47
(c)
"This Policy is extended to cover the employees and/or representatives of the Employer,
consultants, other professional parties and Resident Site Staff whilst on the contract
site as third parties."
(d)
"Notwithstanding anything stated in the Policy to the contrary, cover under the Policy
shall not be suspended in the event of stoppage of work by the Contractor on the
contract site from any cause for a period not exceeding 90 days. In the event of partial or
total cessation of work, the Insured shall use diligence and do all things reasonably
practicable to protect the insured property. Subject otherwise to the Terms Exceptions
and Conditions of this Policy."
(e)
"All deductibles shall be borne by the Contractor."
Insurance for Works
(i)
The Policy shall be issued in the joint names of the Employer and the Contractor.
(ii)
The Works insured shall read the project title given in the Employer's Letter of
Acceptance.
(iii)
The sum insured shall be the same as the Contract Sum.
(iv)
The period of insurance shall commence from the date the Site is handed over to the
Contractor and shall end upon expiry of the Defects Liability Period under the Contract.
The Policy shall firstly cover the whole of the original Contract Period plus 6 months and
plus a further 12 months for Defects Liability Period.
(v)
The period of notice for cancellation of the Policy, if such period is stipulated, shall read
30 days.
(vi)
The policy shall expressly contain the following endorsements:
(a)
"This Policy shall cover all the Contractor's Works insurance obligations stated in the
Contract between the Employer and the Contractor (name of Contractor to insert)".
(b)
"Notwithstanding anything stated in the Policy to the contrary, cover under the Policy
shall not be suspended in the event of stoppage of work by the Contractor on the
contract site from any cause for a period not exceeding 90 days. In the event of partial or
total cessation of work, the Insured shall use diligence and do all things reasonably
practicable to protect the insured property. Subject otherwise to the Terms Exceptions
and Conditions of this Policy".
(c)
"All deductibles shall be borne by the Contractor".
Contract Documents and Reference Material on Site
Keep at the Site the following:
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(a)
A complete set of the signed contract documents described in the Agreement.
(b)
A complete set of the further or revised Drawings and instructions referred to in the Conditions.
(c)
The relevant Codes of Practice or Standards referred to in the Specification.
(d)
These documents shall be made available for inspection and use by the SO, and any other person
authorised by the SO in writing.
Prohibition of Dogs in Construction Sites
Do not rear or keep dogs at the Site for any purposes or under any circumstances, regardless of
whether or not the dogs are licensed with Agri-Food and Veterinary Authority of Singapore (AVA). The
feeding of stray dogs beyond the contract boundary by any site personnel is also prohibited.
The Contractor shall be responsible for complying with this requirement and shall take the necessary
measures which include but are not limited to the following:
(a)
Providing designated waste bins with covers for food waste disposal at workers quarters, workers rest
and recreation areas, and other areas where workers are likely take their meals. The waste bins should
remain closed at all times to prevent dogs from foraging for the disposed food.
(b)
Ensuring that the waste collector removes the food waste from the Site on a daily basis.
(c)
Putting up notices at prominent areas within the Site as well as on the external face of the hoarding to
remind workers and members of the public not to feed stray dogs.
(d)
Having a system of regular site checks which should also cover the secluded spots within the Site
where stray dogs could hide, such as under storage containers. The Contractor shall keep a record of
such checks indicating the days, time and names of site personnel conducting the checks. The records
shall be made accessible to SO upon request.
(e)
Having a system of regular reminders to all site personnel (security guards and customer relations officers
inclusive) on this requirement.
(f)
Informing AVA immediately for assistance if the presence of stray dogs is found within or at the vicinity of
the Site.
If the Contractor is found to have breached the above requirement, the SO may invoke the provisions of
Clause 6 "Nuisance and Irregularities".
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Lightning Protection to Temporary Structures and Metal Structures
Ensure that all temporary buildings such as site office, site electrical substation, workers quarters,
carpenter and bar bending sheds and temporary structures with continuous metal such as steel
framework, scaffolding, tower cranes, batching plants and mobile machinery such as crawler cranes
and concrete pumps are adequately and effectively protected from lightning strike at all times. The
lightning protection system shall be in accordance with and complying with the latest edition of SS
555.
Submit detailed risk assessment and management, drawings showing the design of the lightning
protection system, consisting of the air-termination system, down conductor system and earthtermination system, duly signed by the Contractors PE (Electrical) stating that the design complies with
the latest SS 555. For temporary structures without Lightning Protection System (LPS), a PE certification
with reasons shall be provided. The Contractors PE (Electrical) shall provide a Certification of
Supervision on the lightning protection system together with the earthing reports not later than 3 weeks
after the erection of the temporary structure and before usage. The Contractors PE (Electrical) shall
also conduct routine inspections including submitting earthing reports once every 6 months to ensure
that the Contractor has provided adequate and effective lightning protection system for the Site. The
inspection and earthing reports are to be submitted to the SO and a copy shall be kept in the site
office and made available for inspection at all times.
1.50
Computer Hardware and Software
1.50.1
Computerised Project Management Software
Within one month from the commencement date of the Contract Period, provide and implement a
Computerised Project Management Software (CPMS) during the Contract Period (including any
extension thereof). The SO and the Employer's officers shall be allowed to have full and free access
and usage of the CPMS at all times.
Use the CPMS which shall be installed on the Site to prepare the programme for the Works based on
the Critical Path Method. The programme for the Works shall include the duration, early start/finish
dates, late start/finish dates and floats for all activities involved in the Works. It shall also include
constraints and parameters such as fixed start/finish and target start/finish dates for the activities and
milestones for the different phases or stages of the Works.
The programme for the Works shall comprise summary and detailed reports in textual and graphical
forms. It shall be updated monthly or as and when required by the SO to indicate, inter alia, the critical
path, actual start and finish dates of completed activities, actual start dates and percentage completion of
the activities in progress, and target start and finish dates of the delayed activities, their slippages and
floats.
Submit to the SO the actual programme for the Works within 3 weeks after the Date of Completion.
1.50.2
Computer Hardware
Within one month from the commencement date of the Contract Period, provide the computer hardware
during the Contract Period (including any extension thereof) and till closing of BMT.
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1.50.2.1
Personal Computer
Provide [to be specified by user] Personal Computers (PC) for the exclusive use of the SO and unless
specified otherwise, 3 units of PC for BMT operation. The PC shall comply with the following
minimum requirements:
(a)
An Intel Core i5-4670 Processor of 3.4GHz equivalent or faster processor.
(b)
4 GB DDR3 1600MHz Memory equivalent or better.
(c)
500 GB or more SATA 3.0Gb/s Hard Drive equivalent or better [The hard disk must have 2 partitions
e.g. C and D drive].
(d)
An Intel® HD Graphics 4600 equivalent or better.
(e)
One 24" LCD monitor equivalent or better.
(f)
System BIOS updateable via software should be licensed flash BIOS of the latest version.
(g)
One keyboard.
(h)
One optical USB mouse or compatible.
(i)
One DVD writer.
(j)
Wireless enabled.
(k)
Casing shall be secure and come with one good quality chassis lock of unique combination. AIl keys to
the lock shall be given to the SO.
(l)
Include all the necessary features and accessories required to support the type of broadband connection
services specified in this Clause and all subclauses under it.
(m)
Loaded with the software as specified in this clause including all subclauses under it.
The PC shall be Microsoft certified.
1.50.2.2
Internet Connection
The Contractor shall at its own cost and expense provide and maintain Broadband Connection Services
and WiFi via a major Broadband Service Provider, e.g. Starhub, M1, SingNet or equivalent to be
approved by the SO) for the PC during the Contract Period (including any extension thereof) and till
closing of BMT operation. The minimum connection speed to be provided is as follows:
(a)
50 Mbps for cable broadband, or
(b)
100 Mbps for fibre
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The broadband connection shall be catered solely for the PC. Access to the broadband connection
must be adequately secured with password protection to prevent unauthorised usage or network
eavesdropping.
1.50.2.3
Laser Printer
Provide [quantity to be inserted] laser printer equivalent or better, complying with the following minimum
Specification:
1.50.2.4
(a)
At least 16 MB of RAM and upgradeable to at least 160 MB.
(b)
Able to print at least 20 pages of A4 per minute and 11 pages of A3 per minute.
(c)
Automatic Duplex Printing Unit.
(d)
Print at 600 x 600 dpi resolution or more.
(e)
Support high speed bidirectional IEEE 1284-compliant parallel port (C-type connector).
(f)
Support PCL 5e, PCL 6 and Postscript Level 3 emulation.
(g)
Must be able to support printing in the software specified in this Clause, including all subclauses under it.
(h)
Bundled with drivers for the software specified in this Clause, including all subclauses under it.
Uninterruptible Power Supply (UPS)
Provide [quantity to be inserted] Uninterruptible Power Supply (UPS) equivalent or better, complying with
the following minimum Specification:
(a)
Conform to the following industry standards: IEEE 446, NEMA PE1, ANSI C62.41, IEEE587B, IEC 801146;
(b)
Conform to the following safety standards: UL 1778, CSA C22.2 and VDE
(c)
10 minutes or more runtime at full load
(d)
Provide alert on AC power failure, power restore and diagnostic tests through management software
(e)
Provide at least 3 output ports
(f)
Include all connecting cables joining the UPS output ports and equipment.
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1.50.2.5
Colour Scanner
Provide [quantity to be inserted] colour scanner equivalent or better complying with the following
minimum Specification:
(a)
Flatbed, one-pass colour and monochrome
(b)
At least 600dpi x 600dpi resolution
(c)
Able to scan A4 size documents
(d)
Support Universal Serial Bus(USB) port
(e)
Include(s) scanning software that can display the image file size to users at the preview screen
(f)
Able to support all image formats including but not limited to:
- TIFF
- BMP
- JPEG
- FPX
- GIF
- WMF
- PDF
(g)
1.50.3
Bundled with drivers for the software specified in this clause including all subclauses under it.
Computer Software
Within one month from the commencement date of the Contract Period, provide the computer software
during the Contract Period (including any extension thereof).
Provide the latest version of the following licensed software packages (full packs with original licences,
documentation and media provided) for each PC and/or tablets provided under this Clause, including
all subclauses under it:
(a)
Windows operating system
(b)
Microsoft Project
(c)
Microsoft Office
(d)
Firewall and anti-virus package
(e)
Internet Explorer
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(f)
BIM Revit software
(g)
NavisWorks (for site staff to view BIM model)
Adopt the software listed above so as to ensure compatibility with Consultants IT environment and
applications. Alternative software may be proposed, subject to the SOs approval and provided the
software does not pose any compatibility issues.
Purchase maintenance license for the Virus Scan software to cover the Contract Period (including any
extension thereof). The PC must be set to automatically scan for virus at least once a day when the PC
is switched on.
1.50.4
Computer Software Licensing
All the computer software as specified in this Clause, including all subclauses under it shall be licensed
copies obtained from Authorised distributors or dealers. The Contractor shall at its own cost and
expense provide any software upgrade, to the latest version or release upon request by SO, during
the Contract Period (including any extension thereof). Ensure that only authorised software are used
with the hardware and obtain written approval from the SO before installing any software other than the
ones specified in this Clause including all subclauses under it, into the computer hardware system.
1.50.5
Approval and Testing of Computer Hardware and Software
Submit Specification and details of the computer hardware and software as specified in this Clause
including all subclauses under it to the SO for approval BEFORE the purchase of the hardware and
software. The Contractor shall at its own cost and expense make such necessary arrangement for the
hardware and software to be tested at the relevant Consultant's office and the subsequent delivery to
the work site upon request by the SO.
1.50.6
Computer Furniture and Accessories
Provide the necessary furniture and accessories at the site office to accommodate and facilitate the
usage of the computer hardware and software. The PC designated for the exclusive use of the SO
shall be located in a fully enclosed room within the site office. The room shall be of minimum size 8
m² as specified. The room shall be provided with a lock and be partitioned in half-height glass panels.
1.50.7
Computer System Maintenance
Ensure that the computer hardware and software are in good working condition and pay for all
maintenance, licence fees, subscription fees, etc. for the hardware and software during the Contract
Period (including any extension thereof).
If the Contractor fails to make available the hardware and software within one calendar month from
the commencement date of the Contract Period or fails to rectify any hardware or software faults, within
one day, the SO will make the necessary arrangement to acquire or to rectify the faults and all costs
and expenses thus incurred shall be deducted from payments due to or becoming due to the
Contractor or recovered as a debt due from the Contractor.
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1.50.8
Security
Make all necessary arrangements and provisions to prevent theft/burglary of the computer hardware
and software. Replace any stolen or missing hardware and software within 3 days of such occurrence,
failing which the SO will make the necessary arrangement to acquire the systems and all costs and
expenses thus incurred shall be deducted from payment due to or becoming due to the Contractor or
recovered as a debt due from the Contractor.
1.50.9
Unauthorised Usage
Ensure that the hardware and software are not used for any other purpose except for those approved by
the SO.
1.50.10
Email Account
Apply for and maintain an email account to facilitate transmission of information and
correspondence. Provide the email address to the SO within 1 month from the date of the Letter
of Acceptance.
1.51
Assignment of Copyright of Photographs, etc
Assign the copyright of the photographs (including the prints/slides/transparencies/negative) taken and
all documents prepared under this Contract to the Employer.
The Employer shall have unfettered rights to use or reproduce all the photographs (including the
prints/slides/transparencies/negatives) taken and all documents prepared by the Contractor under this
Contract for any purpose other than for the purpose for into which the Contract was entered.
In the event that third parties are engaged (by the Contractor) to take the photographs (including the
prints/slides/transparencies/negatives) or prepare the documents, procure the assignment of the
copyright from such third parties to itself and thereafter, assign the copyright to the Employer.
The Contractor and/or any third parties are strictly prohibited from using or reproducing any of the
photographs (including the prints/slides/transparencies/negatives) taken and all documents prepared
under this Contract in any other publication or for any other purpose whatsoever.
1.52
Provision of Envelopes for Keys During Handover
Upon successful handover of the Works to the Employer after inspection by the SO and the Employer,
provide the necessary number of envelopes to contain the household keys of each area or room in the
Contract. Each envelope provided shall fulfil the following requirements:
(a)
C6 size (114 mm by 162 mm)
(b)
Key envelope with string and white eyelet
(c)
120 gsm paper
(d)
Colour white
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Propose the type of envelope to the SO for approval.
The 2 external sides of the envelope may either be printed or stamped with the following information:
(e)
On the Front of the envelope Print/Stamp in Arial Black Font Type of Font Size 18, the following
statement: KEY TO PREMISES NO. [to be specified by user]
(f)
On the Back of the envelope: To print/stamp in Arial Black font type of font size 12, the following
statements:
S/N Location
No. of keys
1
[to be specified by user]
2
[to be specified by user]
3
[to be specified by user]
4
[to be specified by user]
Total
1.53
[to be specified by user]
Schedule of PEs Submission
Provide the required PEs submissions as specified for the Works and/or as agreed with the SO. These
submissions shall include but not be to limited the following:
(a)
Site offices
(b)
Temporary buildings
(c)
Passenger cum material hoist foundation, masts and tie-back
(d)
Metal Access scaffold and working platforms.
(e)
Alternative system to safety net system
(f)
Working platforms for lift shafts and voids wall
(g)
Protective Shelter as Overhead Shelter
(h)
Tower cranes and other tall construction equipment foundation and tie-back
(i)
Mobile crane and piling machine access
(j)
Temporary staircases
(k)
Planking and strutting
(l)
Rectification of defective work
(m)
Design of formwork
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(n)
Formwork system for reinforced concrete water tank
(o)
Metal roof structural plans and fastening details
Earth Control Measures
The Contractor shall be responsible for the implementation of effective Earth Control Measures (ECM)
during construction stage at all time. The ECM shall be implemented according to the Code of
Practice on Surface Water Drainage and meet the requirement under the latest Sewerage and
Drainage Act Cap 294.
Note that ECM are meant for the containment and treatment of silty rainwater runoff only, and not
meant for the treatment of process water from construction activities such as slurry from tunnelling, pipejacking and bore-piling works. Such process water shall be handed and treated to comply with the
requirements under Environmental Protection and Management Act (Chapter 94A).
Provide schematic diagrams outlining the ECM for the whole duration of the construction activities,
taking into account the various ECM requirements under different phases of construction activities.
The ECM plan shall be designed and endorsed by a Qualified Erosion Control Professional (QECP)
and form the basis for the Contractor to price for ECM. The Contractor shall be deemed to have
included all the costs and expenses for complying with all ECM requirements in the Contract Sum.
Engage a QECP to design ECM. Implement ECM accordingly to the QECP's ECM plan before earth
works starts. During the course of construction works, engage a QECP to review the effectiveness of
the ECM regularly, in tandem with the various phases of construction works. Revise the ECM as and
when advised by its QECP.
Keep good records of the ECM operation and maintenance. The records shall be made readily
available to the SO.
Do not remove the ECM until all Works are completed and upon the advice of the Contractors QECP.
Submit the ECM plan duly endorsed by its QECP to Director, Catchment and Waterways (PUB) to
obtain the necessary clearance before the earth works start, in the format as prescribed by PUB. The
ECM plan shall include the following content:
(a)
Project Brief, which shall include the following:
(i)
Project description
(ii)
Name and address of site occupier
(iii)
Site area and Contract Period
(iv)
Location map and site plan
(v)
Construction phases and schedules
(b)
ECM Design Calculations
(c)
Erosion Control Plan
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1.54.1
(d)
Sediment Control Plan
(e)
Site ECM Management System
Erosion Control Plan
The plan shall include minimising of bare earth areas/slopes/stockpiles via sequencing and phasing the
earth works, paving up / covering bare earth surfaces with lean concrete, milled waste, erosion control
blankets, close turfing, canvas, etc.
1.54.2
Sediment Control Plan
The plan shall include the following:
1.54.3
(a)
Concrete-lined cut-off drains (minimum C7 precast channel) along the perimeter of the construction sites.
(b)
Sealing of site hoarding.
(c)
Ramp/curb at site entrance/exit.
(d)
Separate drainage for bare earth surfaces and non-bare earth surfaces.
(e)
Silt fence properly installed and embedded onto the ground along the internal and perimeter cut-off
drains.
(f)
Silt traps.
(g)
Holding sumps/ponds for silty water.
(h)
Adequate silty water treatment systems to treat silty water before the discharge points into public drain.
(i)
Turbidity curtains for works in or adjacent to water bodies, such as canals, rivers, sea or in a reclamation
work.
ECM Management System
The Management System shall include:
(a)
Daily ECM inspection and report by an ECM trained site staff.
(b)
Regular ECM review and report by QECP.
(c)
Monitoring and alerts of the treated runoff quality, and if required by PUB, CCTV with Silt Imagery
Detection System to monitor the discharge at the public drain.
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Deploy an ECM trained site staff to supervise the operation and maintenance of the ECM
implemented on site as well as conduct daily checks. The site staff shall be the project manager, a
qualified ECO, RTO or Safety Officer, who has attained, or will attain within 3 months from
commencement of contract, a valid certificate from attending and passing an IES- endorsed ECM
course for site staff, such as "Certificate of Competency in ECM for Construction Site Personnel
Course."
1.55
Environmental Public Health Measures at Construction Sites
1.55.1
General Requirements
Comply with the Environmental Public Health Act (hereafter referred to as "the Act" for the purposes of
this subclause) and its Subsidiary Legislations including the Environmental Public Health (Employment
of Environmental Control Officers) Order 1999, (hereafter referred to as "the Order" for the purposes
of this subclause) and any amendment or re-enactment thereto throughout the Contract Period
(including any extension thereof).
Upon completion of the Works, engage a NEA registered Acoustic professional to measure the
boundary noise for Building Permit application, from sound generating equipment, e.g. cooling towers,
generators, AC condensing units, exhaust fan outlets, refuse compactor; and recommend mitigation
measures when noise levels measured are excessive.
1.55.2
Noise Nuisance
Judicious management and control over the activities within the Site shall be exercised by the
Contractor for the abatement of noise nuisance. In this respect, implement all necessary noise control
measures at its own cost and expense, to comply with the Environmental Protection and Management
Act (hereafter referred to as "the Act" for the purposes of this Subclause) and its Subsidiary
Legislations including the Environmental Protection and Management (Control of Noise at Construction
Sites) Regulations, (hereafter referred to as "the Regulations" for the purposes of this subclause) and
any amendment or re-enactment thereto throughout the Contract Period (including any extension
thereof).
The Contractor shall be deemed to have inspected and examined the Site and its surroundings and to
have satisfied itself as to the surrounding developments and construction activities. Prior to the
commencement of Works, propose a noise management plan and execute the appropriate noise
control measures at its own cost and expense.
1.55.3
Noise Control at Construction Site
1.55.3.1
Noise Management Plan
Within 14 days from the date of the Letter of Acceptance, submit a noise management plan
complying with SS CP 602 to the SO for approval. The noise management plan shall include, but not
be limited to the following:
(a)
Comparison charts between baseline noise monitoring results prior to the commencement of Works and
the anticipated noise emission levels during construction.
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(b)
Identification of sensitive buildings, for example hospitals, schools, institutions of higher learning, homes for
the aged sick, etc., and residential buildings within 150 m from the construction site boundary.
(c)
Site utilisation plan, indicating the locations of site facilities and noise generating equipment including, but
not limited to generators, compressors and concrete pumps.
(d)
Specification of the machinery, equipment and plant proposed to be utilised on site as well as their
indicative noise emission levels. Construction equipment and methods of work that generates excessive
noise will not be allowed to be used on Site.
(e)
Identification of noise generating activities and delineate the sequence of work and construction methods
for such activities, as well as indicate the anticipated noise levels accompanying each type of activity.
(f)
Proposed noise control measures for noise generating activities along with the estimated reduced noise
levels in the form of administrative and engineering controls or other measures deemed effective in noise
abatement. Noise control measures shall take into consideration site planning and layout (administrative
controls), adoption of engineering controls and behavioural considerations of site personnel.
(g)
Proposed scheduling of works with due consideration to noise generating activities.
(h)
Contingency noise abatement measures for unavoidable works that have to be carried out after 7pm with
the approval of the SO.
(i)
Noise monitoring system to be implemented, which includes the details of instrumentation, locations of
installation, measured values of Leq and correction factor to be applied in the presence of ambient noise.
(j)
Public relations strategies to foster close community relationships throughout the Contract Period
(including any extension thereof), such as signboards, newsletters, circulars, complaint handling
procedures and investigation, standard response time to public feedback and complaints
In formulating the noise management plan, take into account the working days and hours, as well as
consider the effects of construction noise on personnel working in or around the site as well as the
neighbourhood within proximity of the Site. Take into account the nature of land use in the area, duration
of works and the effect of lengthening works period or other nuisances that may affect the
neighbourhood.
1.55.3.2
Noise Control Measures
Implement all noise control measures included in the approved noise management plan, including any
other noise control measures as instructed by the SO or NEA from time to time. Noise control measures
shall include the following, where necessary to comply with the Regulations:
(a)
All machinery and plant shall be identified to be sound-reduced prior to entering the Site.
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(b)
All plant, machinery and equipment shall be pasted with a weather-proof sticker clearly indicating its noise
emission level (at source) under normal operating condition.
(c)
All machinery in operation shall have their covers properly shut at all times.
(d)
Noisy plant and equipment shall be housed in acoustic sheds or enclosures.
(e)
Noisy activities shall be barricaded with portable noise barriers and panels.
(f)
Noise barriers shall be erected prior to commencement of works.
Noisy construction equipment (e.g., compressors) and installation (e.g., temporary refuse chute) shall
be sited away from occupied blocks. All construction equipment shall be properly insulated and
maintained to minimise its operating noise level. The SO has the discretion to require the Contractor
to take necessary precautions, whether specified herein or not, to maintain or to repair such
construction equipment or to instruct their removal from site when it is determined that the noise level
generated from the construction works fails to comply with the Regulations or Code.
1.55.3.3
Noise Monitoring System
Set up the wireless, web-based real-time noise monitoring system prior to the commencement of Work
on Site. The cost of setting up, operating and maintaining the noise monitoring system shall be borne
by the Contractor.
The system shall include an integrated solar-powered sound level meter complying with IEC 61672
(Type 1) or other comparable standards approved by the SO. In addition, the system shall provide
wireless, real-time transmission of the sound level data to a secured (password- protected) website,
where data is presented for Leq 5-min, Leq 1-hr and Leq 12-hr periods. The system shall enable all
current and historical sound level data recorded from the Site to be retrieved from the website. The
system shall also incorporate a short message service (SMS) alert system to notify the designated
recipients when the construction noise levels exceed the permissible noise limits stated under the
Regulations.
The sound level meter must comply with the following requirements:
(a)
An integrating-averaging sound level meter set to frequency weighting "A".
(b)
Equipped with a data logger for sampling the running value of "A"-weighted sound level pressure levels
with adequate memory to store 5-min equivalent continuous readings on a 24-hr basis for up to 1 month.
(c)
Dynamic range shall be of at least 40 dB.
(d)
The sound level meter shall have a laboratory calibration certificate dated not more than 3 months before
the commencement date of the Contract. The integrating sound level meter shall be sent to an approved
accredited laboratory for calibration at an interval of every 6 months or as and when required by the
SO.
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Install the sound level meter at a suitable location at the nearest occupied building. The location shall
approved by the SO or NEA. Liaise with the relevant Authorities, for example Town Council, for
permission to install the sound level meter. Where there is no suitable location outside the Site, the
sound level meter may be installed within the Site, subject to the approval of the SO or NEA. The
installed sound level meter can be sheltered, but the microphone of the sound level meter must face
the construction site and in the line of sight of the construction activities without any physical barrier or
obstruction.
1.55.3.4
Sites in Close Proximity to Sensitive Buildings
For construction sites close to premises that are sensitive to noise disturbances, e.g. schools, hospitals,
institutions of higher learning, homes for the aged sick, the SO reserves the right to direct the
Contractor to implement any noise control measures deemed necessary to reduce the noise
disturbances regardless of the noise level generated and compliance with the permissible noise levels
in the Regulations. For the avoidance of doubt, the measures could include, but not be limited to
erection of temporary noise barriers to shield the affected buildings from excessive noise, switching to
use of quieter machinery or adoption of quieter construction methods, installation of air-conditioning
systems within the noise sensitive premises, etc. The Contractor shall also be responsible for
dismantling all temporary noise control measures and shall make good any affected premises when
requested by the occupier of the affected buildings. The Contractor shall obtain written permission from
the SO prior to the dismantling of such measures. The cost of implementation of such measures,
including dismantling, shall be borne by the Contractor.
1.55.4
Landscaping Works
1.55.4.1
Preservation of Trees
Where any existing tree(s) on the Site is stipulated to be preserved (hereinafter referred to as
"Preserved Trees" for the purpose of this Subclause), take all necessary precautions to avoid damage
or injury to such tree(s) and the roots and comply with the following requirements:
(a)
Treatment of Preserved Trees in Area of Fill
(i)
Tolerable Depth of Fill: The area around Preserved Trees shall not be filled more than
300 mm in depth.
(ii)
Construction of Well Around Trees: Well not exceeding 1 m in depth shall be constructed
around Preserved Trees. The minimum diameter of the well shall be 6 times the
diameter of Preserved Trees measured at the trunk 0.5 m above ground level. Details of
the well shall be as shown in the drawings.
(iii)
Treatment of Preserved Trees in Area of Cut
(iv)
Tolerable Depth of Cut: The area around Preserved Trees shall not be cut to a depth
exceeding 300 mm.
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(v)
(b)
Retention of Raised Planter Around Tree: An area around Preserved Trees shall be
retained as raised planter to conserve the root system. The minimum diameter of raised
planter shall be 6 times the diameter of Preserved Trees measured at the trunk 0.5 m
above ground level. Details of retention of raised planter are as shown in the drawings.
Protection of Existing Trees from Physical Damage
(i)
All Preserved Trees shall be protected against damage during construction operation by
suitable fencing or armouring. The protection of Preserved Trees shall be placed before
commencing any excavation or grading operation/work and shall be maintained in repair
for the duration of the Contract Period (including any extension thereof) unless otherwise
directed. The extent of fencing shall be determined by the SO. Fencing shall be erected
all round not less than 1.2 m from the trunk of Preserved Trees.
(ii)
Individual Preserved Trees near heavy construction traffic shall be wrapped with gunny
sacks and 50 mm x 100 mm planks worn vertically as armour around the trunk and
spaced at no more than 50 mm apart to a height of 1.5 m above ground.
(iii)
Any damage to Preserved Trees root system shall be repaired immediately by the
Contractor under the supervision of a qualified horticulturist. Roots that are exposed
and/or damaged during grading operations shall be cut off immediately and the inside of
the exposed and/or damaged area cleaned; cut surfaces shall be treated with approved
sealing compound and topsoil spread over the exposed root area.
(iv)
Any damage to Preserved Trees branches shall be treated in accordance with the
drawings.
(a)
Branch trimming of damaged branches
- First cutting: To be made at point A 300 mm from the main trunk of Preserved Trees;
depending on the diameter of the branch being cut. Depth of cut shall not be more
than ½ of the diameter of the branch.
- Second cutting: To be made at point B parallel to cutting at point A. The distance
between these 2 cuttings shall be 75 mm to 150 mm.
- Make a shallow cut at C.
- Final cut to be sharp and clear.
- Apply coats of anti-fungus wound sealant on cut area.
(b)
Wound treatment
- Clean away ragged or loose edges of bark with a sharp pruning knife.
- Shape the wound into an oval, pointed at both ends
- Coat the entire exposed surface with tree-wound paint.
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(v)
(c)
Health and Condition of Preserved Trees
(i)
1.55.4.2
If any Preserved Trees are severely damaged by any mechanical equipment, etc., make
good such damages and pay for any fines imposed by the Authorities.
Ensure the following:
(a)
Compaction of soil around Preserved Trees shall be avoided.
(b)
No materials shall be stored within the root system.
(c)
There shall be no spillage of any nature within the spread of the Preserved Trees.
(d)
There shall be no parking of vehicles underneath the Preserved Trees.
(e)
There shall be no dumping of excavated materials, concrete, equipment etc., within the
spread of the Preserved Trees crown.
(f)
Soil around Preserved Trees is properly cultivated to ensure that adequate supply of air
and water get to the roots.
(g)
The Site is drained in periods of heavy rainfall and irrigated during periods of drought.
(ii)
Carry out any other routine maintenance of the Preserved Trees, e.g. branch trimming,
pesticide spraying, etc. as instructed by the SO.
(iii)
If the growth of the Preserved Trees is stifled, the Contractor shall inter alia bear the
cost of making good and charges imposed by Authorities, in accordance with Clause 6
on "Nuisance and Irregularities".
Turfing, Landscaping and Tree Planting
Carry out all turfing and planting works to the satisfaction of the National Parks Board (NParks) and/or
the SO. All works in connection with external landscaping shall be considered accepted, only upon the
successful handover to the NParks.
1.55.4.3
Supply and Spreading Approved Soil Mix (ASM)
The Soil Media / Mixture used for general landscape must comply the guidelines specified in the
latest edition of "Specification for Soil Mixture for General Landscaping Use", a publication by Centre
for Urban Greenery and Ecology (CUGE), National Parks Board.
The component of ASM, generally to be used for landscape beds shall be in the ratio 3:2:1 of loamy
soil, compost and washed sand, respectively. The proportions are by volume.
The ASM shall be clear of all lumps of clay, debris, stones, rubbish, hazardous materials, and roots.
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1.55.4.4
Maintenance of Grass
Throughout the Maintenance/Defects Liability Period of the Contract, all turfing shall be watered
regularly and weeded until it is accepted by the SO. All weeds shall be pulled out by the roots. Allow
for such watering and tending. Any dead turves, badly growing turves or otherwise unsatisfactory
turves shall be removed and replaced with approved quality turves by the Contractor at its own
expense. All weeds shall be removed at least twice a month.
All cut grass, cuttings together with trimmings, loose stones, rubbish, etc. shall be collected and removed
from the Site and disposed of expeditiously to the ENV's approved dumping grounds.
After one month until the end of the Maintenance/Defects Liability Period, the Contractor shall carry out
top-dressing with top soil and rolling for any depressions or unevenness of the terrain detected on the
ground.
1.55.4.5
Grass Cutting Frequency
Unless otherwise specified, the frequency of grass cutting for established turf area shall be once
every 2 weeks, until the end of Maintenance/Defects Liability Period. All cut grass within the road
reserves shall be immediately swept and removed.
1.55.4.6
Tree and Shrub Planting
Unless otherwise specified, provide the necessary specified tree saplings and shrubs, plant and
maintain them till established. Replace any trees or shrubs that die or are in a poor state of growth or
had failed to establish.
All plants proposed and the planting plan must be approved by the SO.
Any plants replaced within the last 3 months just before the end of the Maintenance/Defects Liability
Period, the Contractor shall undertake to maintain the plants for a period of 3 months commencing from
the date of the plants replaced.
At the end of Maintenance/Defects Liability Period, the plants must be healthy, lush and undamaged.
At the end of Maintenance/Defects Liability Period, rectify all defects to the satisfaction of the SO.
1.55.4.7
Watering
Immediately after planting, water the trees and shrubs and continue to do so at least once a day and as
and when required until the trees and shrubs are well established and need no further daily watering.
The Contractor is expected to water the plant at any time during the Maintenance/Defects Liability
Period whenever it is required and as directed by the SO, all at the Contractor's expense.
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1.55.4.8
Maintenance of Trees and Shrubs
Carry out all necessary maintenance of the planted trees and shrubs. Maintenance shall mean
watering and replacement of trees or shrubs that failed to establish, replacement of tree guards and
stakes, proper pruning and trimming, weeding and clearing of unnecessary growth such as weeds and
"lallang", at least once a month or at any time as directed by the SO, liming, feeding, forking of soil
around the plant base (area of planting hole or bed) spraying with approved pesticide, adding
compost to the top 50 mm, etc. all at Contractor's own expenses.
The period of maintenance begins as soon as a tree, shrub or sod of turves is planted up to the end of
the Maintenance/Defects Liability Period .
If the Contractor fails to carry out regular maintenance of the turves and trees as stipulated, the SO
shall engage others to carry out the necessary maintenance work. All expenses arising therefrom
shall be borne by the Contractor and shall be deducted from any monies due or to become due to the
Contractor, including 20% administration charges.
1.55.4.9
Handover
Turfs, trees and shrubs planted in public areas, e.g. within road reserves shall be handed over to
NParks. Carry out regular weeding, cut the turf, top dressing, prune the trees and shrubs, etc., and
get them ready to a standard acceptable to NParks for inspection and taking over.
Attend all site inspection by NParks and comply with all requirements and comments by NParks including
any re-inspections till the turves, trees and shrubs are accepted and taken over by the relevant Authorities
all at the Contractors own expenses.
Note that the taking over of the road is dependent on the taking over of turves, trees and shrubs within
road reserve. The Contractor shall therefore have to attend expeditiously to all NParkss requirements
and comments.
Trees, shrubs and turves in other areas shall be to a standard acceptable to the SO for handover to
relevant Authorities.
Allow for the compliance of the above requirements in its Tender Price.
1.55.4.10 Turfing / Grass Cutting Within Road Reserve
Commence turfing works progressively as the side tables are ready. Proper care shall be taken to
ensure that the turf covers the full area in time for the inspection by NParks for taking over, otherwise
the close turfing shall have to be provided, all at the Contractors own costs.
Carry out grass cutting once in 2 weeks throughout the Contract Period. Continue to maintain the turf
by submitting schedule of maintenance to SO till successful handover the turf to relevant Authorities
or NParks.
The schedule of maintenance includes monthly weeding, fortnightly grass cutting, rolling, top dressing,
mulching to trees and shrubs, pest and disease control, and nutrient management regime.
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1.55.5
Temporary Site Access Within Site Boundary
Propose and construct a temporary site access within the Site boundary linking the main construction
entrance/exit to all building blocks, inclusive of multi-storey carpark building.
Engage a PE to design the access. The drawings and calculations endorsed by the PE shall be
submitted to the SO for approval before the construction of the access. The access shall be of
concrete or bituminous pavement or precast concrete plank. It shall be laid over well- compacted
hardcore base or other suitable material to the Contractors PE design. The access shall be inspected
by the Contractors PE and the certificate of supervision issued prior to use.
The precast concrete plank shall be 175 mm thick with modular size of 1.20 m by 2.20 m. The
Contractor can opt for any other size subject to the SOs approval. It shall be reinforced with welded
mesh and the edges shall be protected with angle iron. It can be cast with grade 40 eco-green
concrete.
To ensure proper site drainage, properly-graded Type C7 composite channel cut-off drains shall be laid
along the perimeter of the construction site. Similar cut-off drains shall be laid along the access and
other areas where required. The drainage system shall comply with the requirements specified in
Clause 1.55 on "Earth Control Measures" and subclauses under it.
The area between the temporary site access and the building blocks / multi-storey car park shall be
laid with well compacted subgrade with lean concrete surface.
The access shall be provided immediately after the completion of the first storey. The provision of
access prior to the completion of first storey shall comply with the requirements specified in Clause
5.1.14 "Access for The Use of Mobile Crane and Piling Machines Next to Built-Up Area". The
access shall be maintained in good working condition and free from water stagnation at all times
throughout the Contract Period (including any extension thereof), or unless otherwise approved by
the SO.
As part of the housekeeping effort, deploy workers to clear the mud deposits/droppings regularly and
maintain the access as clean and dry as practically possible. A heavy duty vehicular washing bay shall
also be provided at the main entrance/exit point abutting completed public road. All tyres of vehicles
shall be thoroughly clean if necessary before leaving the Site.
The area at the main construction entrance/exit shall be laid with concrete surface to improve the
maintainability of the site access. Where the access had been excavated for underground services
work (e.g., sewer construction, underground piping system draw pit), use steel plate to temporarily
cover these excavated areas and the access shall be immediately reinstated to good working
condition upon the completion of the underground services work in accordance to PE design.
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1.55.6
Temporary Sanitary Facilities
Within 21 days from the date of the Letter of Acceptance, provide temporary sanitary facilities in suitable
structures with adequate lighting, on the Site. Such temporary sanitary facilities shall be subject to
approval by the SO. Use the Employer's Standard Drawings as a guide in designing the temporary
sanitary facilities. The temporary sanitary facilities shall comprise water closets and shower
compartments in the proportion of one closet and one shower to every 25 workmen, throughout the
Contract Period (including any extension thereof). In addition, provide separate sanitary facilities with
water closet and shower compartment for the exclusive use of the Employer's officers. Prior written
approval by the SO shall be obtained before commencing the erection of these facilities.
The water closets shall be of the type, make and pattern approved by the MEWR and PUB (Water).
Provide and lay glazed wall tiles or other approved material to the internal walls of the temporary
sanitary facilities up to a height of 1.8 m from the floor. The doors to the cubicles of the temporary
sanitary facilities shall be of approved material.
All waste discharge from the water closets and all waste water from the temporary sanitary facilities
and from the Site shall be discharged into a public sewer. Arrange with the MEWR to carry out
connection work from the temporary sanitary facilities to the public sewer and pay all charges and
maintenance in connection therewith. The Contractor shall be responsible for all damages to and shall
indemnify the Employer against all liabilities in respect of such sewer connections.
Where a public sewer is not available or where it is not possible to connect to a public sewer, provide
and install temporary septic tanks of the type, pattern and capacity approved by the MEWR, to serve
the water closets, showers and baths.
Prior to commencing the installation of the temporary septic tanks on the Site, engage a Licensed
Plumber who shall submit his/her proposal to the MEWR and SO for approval. The proposal shall
include the manner and frequency of post installation management and maintenance of the septic
tanks on the Site. The Contractor and its Licensed Plumber shall be fully responsible for any
mismanagement or misuse of the temporary sanitary facilities, which may result in the pollution of the
controlled water course.
1.55.7
Removal of Construction Debris from Building Blocks
Before the commencement of Works on site, submit proposal for the daily removal of the construction
debris from the building blocks to the SO for approval.
1.55.8
Pest Control and Surveillance
Engage an approved Pest Control Operator who is registered with the following to provide
comprehensive pest control and surveillance work on the Site:
(a)
BCA, under the Work Head for Pest Control
(b)
NEA, under the Control of Vector and Pesticide Act
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In this respect, submit the name of the Pest Control Operator and proof of BCA/NEA registration to
the SO for approval prior to carrying out the Works. The SO may reject the Pest Control Operator
selected by the Contractor and the Contractor shall not be entitled to any claims for compensation and
extension of time arising from such decisions.
Pest Control measures and surveillance programmes shall fully comply with the requirements of NEA
as well as the following:
(a)
The Contractor is required to submit a detailed pest control and surveillance programme inclusive of
"Source reduction regime/strategy", "Water bearing receptacle removal team" at the Site to the respective
NEAs regional office and the SO prior to commencement of the Works. The frequency of fogging shall be
in accordance to NEAs requirement. Fogging shall be carried out only by licensed Pest Operator using
approved chemical.
(b)
The Contractor shall maintain a site register containing an up-to-date record of the pest control and
surveillance work that has been carried out. The site register shall be made available and ready for
inspection by the SO when required.
(c)
The Contractor shall submit monthly summarised returns of the site records required by NEA to the
respective NEAs regional office.
(d)
On the instruction of the SO, the Contractor shall seal up all sanitary openings in the dwelling units prior
to the handover of the completed Works all at the Contractor's cost and expense.
The works required under this subclause shall include all necessary measures to prevent the Site from
becoming conducive to the breeding or harbouring of vectors. Carry out site checks at least once a
week to detect and remove all breeding and harbouring grounds. If breeding or harbouring of vectors
is found at the Site, enforcement action may be taken against the Contractor by NEA. The SO may
also invoke the provisions of Clause 6 "Nuisance and Irregularities".
1.55.9
Air Pollution by Construction Equipment
Take all necessary measures to abate the discharge of smoke, fumes or obnoxious gases from
construction equipment and other equipment on the Site. When notified by the SO that a particular
construction equipment or equipment is discharging excessive smoke, fumes or obnoxious gases, stop
the use of that construction equipment or equipment, and replace the same with acceptable
construction equipment or equipment. No claims from the Contractor for extension of Contract Period or
costs and expenses shall be allowed.
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1.55.10
Cleaning of Public and Private Roads and Drains
Ensure that all vehicles used by the Contractor, the Contractors agents, or by the Contractors
subcontractors or suppliers and their agents (hereinafter referred to as the "Contractor's Vehicles" for
the purposes of this subclause) shall not dirty any public or private roads and drains. In this respect, it is
the Contractor's responsibility to ensure that all such Contractor's Vehicles are properly cleaned
before they move onto these roads.
Check with the SO if it is in doubt of any road being a public or private road and the decision of the SO in
this respect shall be final and binding and conclusive against the Contractor.
In the event the Site abuts a public or private road and the Contractor's Vehicles use the road for site
access, provide a washing bay to wash and clean Contractor's Vehicles before they move onto the
public or private road. Should vehicles of the other contractors also use such public or private road for
site access, provide, at the Contractors own cost and expense, similar washing and cleaning facilities
and services for these other contractors' vehicles before they move onto the public or private road.
Provide also at the Contractors own cost and expense, the same facilities and services for similar
purposes in the event a road abutting the Site becomes a public or private road and is used for site
access by the Contractor's Vehicles or other contractors' vehicles.
1.55.11
Restriction on The Use of Styrofoam in Construction processes
The use of styrofoam in the course of formwork erection or concreting works shall be disallowed,
unless specific approval has been given by SO.
The Contractor shall also ensure that its subcontractors do not use styrofoam in openings and recesses.
1.56
Material Sample Display Room
Within 21 days from taking possession of the Site, a Material Sample Display Room of 3 m X 5 m (i.e.
15 m2) shall be provided at the Site office and situated beside the meeting room. A new air-conditioner
and adequate lighting shall be provided to the Material Samples Display Room.
Appropriate and proper display racks/shelves shall be provided. The display room shall be maintained
neat and tidy at all times.
1.57
Audit of M&E Systems
Test the M&E systems and rectify all defects before submitting all M&E systems test reports
endorsed by the professional engineers and licensed electrical worker (LEW) engaged by the
Contractor. The Employer reserves the right to audit any of the M&E systems installed by the
Contractor. Provide the necessary manpower, equipment and means of access for the audit by the
Employer. Rectify all defects detected during the audit and report to the Consultant for verification.
For buildings under construction, ensure compliance with the requirements of the FSSD (dry/wet
rising mains, etc). Make the necessary arrangements to enable the officers from FSSD, SO, and/or
the Employer to carry out any inspection and testing during the construction stage.
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1.58
Environmental Management
1.58.1
Environmental Management Programme
1.58.2
(a)
Implement an effective Environmental Management Programme.
(b)
The Programme shall include monitoring and tracking to minimise:
(i)
electricity consumption
(ii)
diesel consumption
(iii)
water consumption
(iv)
concrete wastage.
(c)
Submit data to the SO on a monthly basis and present it as a standing item in the monthly meeting.
(d)
The programme shall also include measures to be taken to raise awareness and promote environment
friendly habits amongst site personnel.
Environment-Friendly Practices
(a)
Implement a system to facilitate the use recycled water obtained through Earth Control Measure for:
(i)
wash bay
(ii)
dust control
(iii)
tremie piles
(iv)
washing of site access.
(b)
Segregate metal and concrete waste from general construction waste for recycling purpose.
(c)
Provide recycling bins near the site office to facilitate recycling.
(d)
Use eco-green concrete, subject to Contractors PE approval where necessary, for the base slab of:
(i)
site office
(ii)
workers quarter
(iii)
workers toilet
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(iv)
(e)
1.59
cube room.
To reduce energy consumption for the Site Office, the contractor is encouraged to carry out the following:
(i)
Use aircon with green rating.
(ii)
Use white colour for the roof of the site office.
(iii)
Use the east and west end for meeting room or toilet as it has lower occupancy.
(iv)
Reduce the office ceiling height at about 2.4 m to reduce air conditioning and lighting
energy consumption.
(v)
Provide ultra violet film or blinds at site office windows.
(vi)
Maintain office temperature at more than 24°C.
(vii)
Provide door closer at doors where space is air conditioned.
(viii)
Design the site office toilet such that they do not need mechanical ventilation.
(ix)
Use pedestal pan integrate with wash basin.
(x)
Use motion sensor for lights and ventilation fan for toilet.
(xi)
Orientate the site office in the northsouth facing if feasible.
(f)
The Contractor is encouraged to be familiar and closely follow the BCAs Green and Gracious Builders
Guide (e.g. use energy efficient air conditioning system complying with Singapore Energy Labelling
Scheme, use T5 lights combined with motion sensors to reduce energy consumption).
(g)
The Contractor is also encouraged to:
(i)
provide more greening on Site to lower ambient temperature during construction period
(ii)
eliminate environmentally unfriendly products and packaging.
Protection of Personnel Data
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1.59.1
Security
Take all reasonable measures to ensure that Personal Data held in connection with this Contract is
protected against loss, and against unauthorised access, use, modification, disclosure or other misuse
in accordance with the procedures set out in this Clause and its subclauses, and that only authorised
personnel have access to the data.
Do not vary the security procedures set out in this Contract without the prior written approval of the SO.
1.59.2
Use
Use any Personal Data held in connection with this Contract only for the purposes of fulfilling its
obligations under this Contract.
1.59.3
Disclosure
Do not disclose any Personal Data obtained in connection with this Contract without the written
approval of the SO. Immediately notify the SO when it becomes aware that a disclosure of Personal
Data may be required by law.
1.59.4
Transfer of Personal Data Outside Singapore
Do not transfer Personal Data held in connection with this Contract outside Singapore, or allow parties
outside Singapore to have access to it, without the prior written approval of the SO.
1.59.5
Data Protection Requirements and Undertakings
Ensure that any employee of the Contractor or any subcontractor, requiring access to any Personal
Data held in connection with this Contract gives an undertaking in writing to not access, use, disclose
or retain Personal Data except in performing their duties of employment and is informed that failure to
comply with this undertaking may be a criminal offence and may also lead the Contractor to take
disciplinary action against the employee.
In respect of any Personal Data held in connection with this Contract, immediately notify the SO where
the Contractor becomes aware of any breach of the obligations contained herein by itself or any
subcontractor, or by their respective employees.
In respect of any Personal Data held in connection with this Contract, cooperate with any reasonable
requests, directions or guidelines of the Employer, or Employers nominee/agent, arising in connection
with the handling of Personal Data.
All the above Clauses shall continue to have effect after the termination or expiry of the Contract.
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1.59.6
Subcontracting
Whether or not the Contract contains clauses that prevent subcontracting or assignment without the
consent of the SO, the written approval of the SO must still be obtained pursuant to the clauses
herein, before any Personal Data can be disclosed to any subcontractor or assignee. Ensure that all
clauses relating to protection of Personal Data are included in any Contract between the Contractor
and subcontractor or assignee.
2
MATERIALS
2.1
Metric Components
All components for incorporation into the Works shall be in metric units. However, when metric
components are not available, their equivalent in imperial units may, subject to the approval of the SO,
be used and such a substitution shall not constitute a variation to the Contract.
2.2
Materials and Workmanship
As directed, furnish the SO with approved documents to prove that materials are as specified. The
documents shall include but not be limited to any or all of the following, such that the authenticity of the
materials can be easily ascertained:
(a)
shipping documents
(b)
serial numbers
(c)
warranty certificates
In the event that any documents submitted are not original copies, they shall be duly certified by the
originating parties. No information within the documents shall be tampered with, unless it is clearly
discernible that the items are not related to the materials specified in the Contract.
Where specific brand and model number are specified, or where alternative brands and model
numbers are offered by the Contractor and accepted by the SO, it shall be deemed that the finished
products are entirely of original make by the registered manufacturer and fully supported by the
manufacturer's warranty. In the event that any alteration is made to the goods by a local agent or any
other intermediary, obtain the approval of the SO shall be sought and the result of the alteration shall
be fully supported by the manufacturer such that the manufacturer's warranty is maintained.
Samples of materials shall be submitted to the SO for approval before order is placed with the supplier.
Such approval by the SO shall not relieve the Contractor of its obligations under the Contract. Ensure
that the materials are free from any defects, damage or any other flaws.
2.3
Sample , Mock-up and Quality Standards
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2.3.1
Sample, Mock-up and Quality Standard
All samples shall be provided as per the requirements of each technical section of the Specification.
The cost and expense for inspection, testing and approval of sample and mock-up (as instructed by
the SO), shall be provided by the Contractor. These samples and/or mock-ups shall be truly
representative of the actual works to be constructed in every respect, inclusive of all architectural
details, architectural and structural features, finishes, services, fittings, etc.
Comply with the quality standards specified under each Section for setting up of sample and/or mockup. Read the Specification, drawings or details in conjunction with the quality standards specified under
each Section. In case of discrepancies between the Specification, drawings or details and the quality
standards specified under each Section, obtain approval from the SO before proceeding with the
Works.
Use the approved sample and/or mock-up as reference for the standard and quality of workmanship
and materials that are acceptable to the SO. Ensure that the completed Works (including works that are
not listed in the quality standards specified under this clause) are at least of the same standard and
quality as that in the samples.
Maintain the sample and/or mock-up in a clean, neat and tidy condition at all times. Adequate artificial
lightings shall be provided where possible and as directed by SO, all at the Contractors cost and
expense.
Notwithstanding the approval of the SO in respect of these sample and/or mock-up units, the Contractor
shall not be released from any of the duties and obligations as required of the Contractor under the
Contract.
These samples shall be appropriate displayed at the designated area within the Material Sample
Display Room upon approval of the said sample by the SO.
The SO reserves the right to instruct the Contractor to provide and display the sample for other building
materials and components, especially newly introduced items, big ticket items and special items, under
the Contract where deemed necessary and fit all at the Contractor's cost and expense. The approved
material samples shall be provided and displayed before construction, erection or installation. All
approved materials shall be labelled with the supplier's name and materials' type/grade/model.
2.4
Storage Facility for Cement
Where storage of cement is required, provide adequate storage facilities at the Site to accommodate
cement up to 2 weeks' requirement for the Works.
The store to accommodate the cement shall be constructed so that each consignment of cement can
be separately stacked. Each consignment of cement shall also be used in the same sequence as they
are delivered, that is, on a "first-in first-out" basis.
Ensure that the cement stored at the Site is kept dry and properly protected against loss or damage at
all times.
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2.5
Precautions Against Materials Being Taken Out Of Site
The Contractor shall be responsible for the safe custody of cement and all other materials delivered
to the Site and shall therefore ensure adequate protection and prevention of such materials from
being taken out of the Site. The SO will not accept any excuse for materials taken out of the Site by
the Contractor, the Contractors foreman or any other individual even without the knowledge of the
Contractor who is deemed to have provided for proper control against such malpractice. If it is
established that cement or any other material is taken out of the construction Site without specific
written approval from the SO, this shall be deemed to be an irregularity, with penalties to be imposed
by the SO.
2.6
Ready-Mixed Concrete from Approved Suppliers
Obtain ready-mixed concrete from any of the pre-approved suppliers and provide the names and
addresses of the ready-mixed concrete suppliers to the SO. The use of ready-mixed concrete shall
be subject to the terms and conditions set by the SO. All delivery orders for ready-mixed concrete
delivered to the Site shall be endorsed by the Employer's Resident Site Staff and submitted to the
SO.
Failure to inform the SO or non-compliance with the terms and conditions set by the SO for the use of
ready-mixed concrete shall, inter alia, result in the Contractor forfeiting its right under the Contract to claim
compensation for price fluctuations for all materials.
2.7
Provision of Spare Materials
Provide all spare materials as specified under each Section.
3
LABOUR
3.1
Labour Laws
Pay workmen (Contractors workmen) promptly, and observe the workmen's working hours and holidays
in accordance with current laws and regulations. Keep records and produce them for inspection by the
SO.
3.2
Keeping Records of Workmen
Comply with all labour laws regarding the engagement of non-citizen workmen. Obtain work permits
from MOM for these workmen. The Contractor shall be held solely liable for and shall indemnify the
Employer in respect of all actions against the Employer for employing foreign workmen without permits.
Keep proper records of all workmen engaged on Site. These records shall include the following
information:
(a)
Name of Workmen (and alias if any)
(b)
Identity Card No./Passport No.
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(c)
Address
(d)
Work Permit No., if any
(e)
Expiry date of work permit
This information shall be recorded before any workman is allowed to commence duty.
Appropriate action shall be taken by the SO if the Contractor fails to record any of the
abovementioned information of any worker found at the Site.
3.3
Employment of Illegal Immigrants (Prohibition)
For the purpose of this Subclause, an "illegal Immigrant" shall refer to any person who enters the
Republic of Singapore in contravention of the provisions of the Immigration Act or any statutory
modification or re-enactment thereof.
The Contractor shall ascertain the legitimacy of all foreign workers employed by itself and/or any
subcontractor prior to employment and throughout the Contract Period (including any extension thereof).
Clarification as to the legitimacy of Foreign Workers may be made with the Immigration Authority, the
Ministry of Manpower and/or the Police.
The Contractor and/or its subcontractors shall not employ any illegal immigrants in the execution of the
Works. The Employer shall not be responsible for any such act or acts by the Contractor and/or any of
its subcontractors and the Contractor shall indemnify the Employer for all consequences arising
thereof.
3.4
Biometric Time Attendance System for Manpower Data Collection
Propose, supply, deliver, install and set up a biometric time attendance system, including testing and
commissioning, and subsequent maintenance of a biometric time attendance system for personnel
entering or leaving the worksite throughout the Contract Period. Propose the mode of authentication
(fingerprint, facial recognition, etc.).
The system shall be located at all worksite entrances and exits for the purpose of electronically
monitoring and tracking the manpower usage throughout the Contract Period. Install a CCTV at
locations with the biometric time attendance system. The system shall be installed and functional upon
completion of the perimeter hoarding and site entrance.
Submit a detailed proposal to the SO for approval within 14 days from the date of the Letter of
Acceptance. The proposal shall include, but not be limited to, the following details:
(a)
Type of system to be implemented
(b)
Track record of proposed system in similar projects and environment in Singapore
(c)
Proposed location(s) of the system at Site
(d)
Type of access barrier (e.g. tripod turnstile, flap barrier, swing barrier etc.)
(e)
Installation method
(f)
Maintenance plan
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The system shall be able to accurately monitor and track the manpower under their respective trade.
At each controlled access location, the system shall be able to achieve a maximum clearance time of 1
minute for every 10 persons.
The system shall be able to generate the manpower report according to BCAs current Electronic
Productivity Submission System (ePSS) in Microsoft Excel format (Refer to
https://www.bca.gov.sg/epss/ ). Refer to BCAs website for the latest requirements on manpower
submission to ePSS.
The system shall be able to generate raw data or output in the required format which shall include but
not limited to, the following details:
(a)
Employee name
(b)
Date
(c)
Clock in time
(d)
Clock out time
(e)
Total number of working hours at site
(f)
Classification of workers (e.g. tiler, painter)
(g)
Personal identification number (i.e. NRIC/ FIN/ WP no.)
(h)
CoreTrade Registration ID
The system shall be able to generate trend charts to show the total manpower used in man- days
under the respective trade over time.
There shall be a real time monitoring and recording device installed at each controlled access point to
prevent any fraudulent attempt by the site personnel.
The system shall be equipped with suitable measure(s) (e.g., backup battery supply etc.) such that the
integrity of the manpower monitoring data is not affected during power outage. Ensure that the system
is protected against unauthorised editing of collected manpower tracking data, virus or malicious
software which may otherwise corrupt the system.
In the event of system breakdown, ensure that there are alternative mean(s) to continue to monitor
and track the manpower under the respective trades. The Contractor shall bear all costs and expenses
in carrying out the necessary repairs and/or replacements to the equipment installed to resume
system operation.
Submit the manpower tracking data in the Contract to BCA through the ePSS at monthly intervals or
at other frequencies as required by BCA. A copy of the submitted manpower report shall also be given
to the SO.
Extend usage of the system to the Employer and Consultants. The list of personnel required to use the
system shall be as agreed with the SO.
The system shall be able to generate raw data or output which shall include but not limited to, the
following details:
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(a)
Employee Name
(b)
Company
(c)
Designation
(d)
Date
(e)
Clock-in Time
(f)
Clock-out Time
(g)
RE and RTO registration number
Access rights control shall be given to the personnel as summarised in the table below:
Access Rights
Attendance Record
Contractor
Consultant
Employer
Employer
Yes
Yes
Yes
Consultants
Yes
Yes
No
Contractors
Yes
No
No
At the end of every month, the Consultant Project Manager shall generate the manpower data and
submit to the Employer.
3.5
Allocation of Man-Year Entitlements
Where materials, goods or products for the Works in the Contract are to be purchased and/or obtained
by the Contractor, allocate Man-Year Entitlements to such suppliers and/or subcontractors engaged
(by the Contractor) for the supply of such materials, goods or products.
The Contractor shall be deemed to have included in the Contract Sum for all costs and expenses
arising from having complied with the requirements stipulated in this subclause.
3.6
Employment of Skilled Workers
Employ workers that are capable of producing good workmanship for all key trades as agreed with the
SO. These workers shall possess Skill Evaluation Certificate from local institutions where available.
Submit a list of the workers to the SO for pre-screening and approval before they are allowed to
commence work. These workers are also required to wear identification pass upon approval by the
SO. The pass shall be easily distinguishable from other passes used at the Site, by their colour, size or
pattern.
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4
CONSTRUCTION EQUIPMENT
Provide information on the construction equipment to be deployed to the Site within 3 months from the
date of the Letter of Acceptance to the SO for approval. Notwithstanding the submission for SOs
approval, when deemed necessary, the SO may instruct the Contractor to deploy additional
equipment to the Site. No claim by the Contractor for additional payment/s will be allowed for these
additional pieces of equipment. Similarly, no claim by the Contractor for additional payment will be
allowed for additional equipment brought to Site by the Contractor on its accord.
All construction equipment used at the Site as specified herein shall be obtained from reliable source,
subjected to the Consultants approval.
Where such construction equipment is used at the Site for a duration of less than a week, the SO may
at his sole discretion, waive the aforementioned requirement. Under such a case, there shall be no
adjustment to the Contract Sum.
4.1
Maintenance
Keep all construction equipment provided to the Site in good working order at all times and comply with
all statutory regulations in relation to the construction equipment.
4.1.1
Mobile Crane
Before operating a mobile crane on the Site, submit the following:
(a)
Record of latest overhaul servicing of the crane. The latest overhaul servicing of the crane shall be
conducted within 1 year before transferring it to the Site.
(b)
Record of checking the connecting devices between parts/components and the condition of
parts/components by an AE. Any defect found when checking shall be rectified immediately; and
(c)
Certificate of test/thorough visual examination of lifting equipment by the AE.
Maintain the crane in good working order at all times on the Site. Document and keep all records and
certificates of checking and testing in the site office for inspection by the SO upon request. Attend to the
following:
4.1.2
(d)
Engage a licensed crane operator to check the crane daily before operation. The licensed crane operator
shall have a Certificate of Competence.
(e)
Engage a competent mechanic to conduct servicing of the crane once in every 3 months.
(f)
Engage the AE to carry out test and visual examination on the crane once in every 6 months.
Tower Crane
Before operating a tower crane on the Site, submit the following:
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(a)
Record of latest overhaul servicing of the crane. The latest overhaul servicing of the crane shall be
conducted within 1 year before transferring it to the Site.
(b)
Record of checking the connecting devices between parts/components and the condition of
parts/components by an AE. Any defect found in the checking shall be rectified immediately.
(c)
Record of checking the installation and functioning of safety devices by the AE; and
(d)
Certificate of test/thorough visual examination of lifting equipment by the AE.
Maintain the crane in good working order at all times on the Site. Document and keep all records and
certificates of checking and testing in the site office for inspection by the SO upon request. Attend to the
following:
(e)
Engage a licensed crane operator to check the crane daily before operation. The licensed crane operator
shall have a Certificate of Competence;
(f)
Engage a competent mechanic to conduct servicing of the crane once in every 3 months;
(g)
Engage the AE to check the installation and functioning of the safety devices once in every 6months; and
(h)
Engage the AE to carry out test and visual examination on the crane once in every 6 months.
For every extension of height made on the tower mast and before operating the crane with the new
height, engage the AE to conduct test and thorough visual examination on the crane.
4.1.3
Passenger Cum Material Hoist
Before operating a passenger cum material hoist on the Site, submit the following:
(a)
Record of latest overhaul servicing of the hoist. The latest overhaul servicing of the hoist shall be
conducted within 6 months before transferring it to the Site.
(b)
Record of checking the connecting devices between parts/components and the conditions of
parts/components by an AE. Any defect found in the checking shall be rectified immediately.
(c)
Certificate of test/thorough visual examination of lifting equipment by the AE.
Maintain the hoist in good working order at all times on the Site. Document and keep all records and
certificates of checking and testing in the site office for inspection by the SO upon request. Attend to the
following:
(d)
Require an authorised hoist operator to check and operate the hoist daily before operation.
(e)
Engage a competent mechanic to conduct servicing of the hoist once in every 3 months.
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(f)
Engage the AE to check the connecting devices between parts/components and condition of
parts/components once in every 3 months. Any defect found in the checkings shall be rectified
immediately.
(g)
Engage the AE to carry out test and visual examination on the hoist once in every 3 months.
(h)
The swing gates are to be maintained, checked and certified to be in good working condition by the AE
every month.
(i)
Interlocking gates shall be provided at every lift landing level and they shall comply with the Workplace
Safety and Health Act and its Subsidiary Legislation including any amendment or re-enactment thereto.
4.2
Provision and Deployment of Equipment to Improve Site Productivity
4.2.1
Construction Machinery and Equipment to be Deployed at the Site
The Contractor shall provide and deploy suitable construction machinery and equipment to improve site
productivity. The Contractor shall submit the Machinery Utilization Plan within 3 months from the date of
the Letter of Acceptance to the SO for approval. The Contractor shall provide for a minimum of one
number of ride-on power trowel, one boom lift, one scissors lift and one telescopic handler.
Notwithstanding the foregoing requirements, the Contractor shall provide an Automatic Wheel Washer
per site entrance and a Mast Work Platform per building block.
4.2.2
Technical Specification
(a)
Ride-on Power Trowel
The power trowel shall be used for power floating of finished concrete to achieve a smooth finish in
accordance to the Drawings and Specification. The requirement for provision of the power trowel may
be waived at the discretion of the SO if the Contract does not require power floating of finished
concrete.
(b)
Boom Lift and Scissors Lifts
The boom lift and scissors lift shall be used for any work that is needed to be carried out at soft storey,
void deck space and external façade. The boom lift and scissors lift shall also be used for rectification
works from the second storey to sixth storey for the building during the handing over stage.
(c)
Telescopic Handler
The telescopic handler shall be provided on Site not later than the completion of concreting work for
the sixth storey slab of the first building block or any other time as instructed by the SO and shall not be
removed without his prior approval.
(d)
Mast Work Platform
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The mast work platform shall be used for any external façade works (skimming and painting) for each
building block in preparation for handing over. The requirement for provision of the mast work platform
may be waived at the discretion of the SO if the layout of the building block does not allow for erection
of mast work platform.
(e)
Automatic Wheel Washer
The automatic wheel washer shall be used to replace the manual manpower needed at the site
entrance to wash and clean the wheels of the vehicles leaving the Site. The Wheel washer shall be
provided onsite upon completion of substructure works or at any time instructed by the SO and shall
not be removed without his prior approval.
(f)
Wireless Cleaning Machine
The wireless cleaning machine is a multi-function auto scrubber which delivers effective and efficient
floor cleaning performance. It is able to wash and dry hard floors in a single pass, saving labour as
compared to the 2-man rotary scrubber and vacuum cleaner method. The wireless cleaning machine
shall be provided on site at block handover stage or at any time instructed by the SO and shall not be
removed without the SOs prior approval.
(g)
Electric Sanding Machine
The electric sanding machine is an equipment used to smoothen the wall and ceiling surface. It shall
replace the manual sanding method by using sandpaper to smoothen the wall and ceiling surface. The
electric sanding machine shall be provided on Site upon completion of superstructure works or at any
time instructed by the SO and shall not be removed without the SOs prior approval.
5
SITE SAFETY
5.1
Site Safety Measures
5.1.1
General Requirement
The Contractor shall allow for the compliance with the Workplace Safety and Health Act and its
Subsidiary Legislation including the provisions of the Workplace Safety and Health (Construction)
Regulations and any amendment or re-enactment thereto. The subsidiary legislations are:
(a)
The Workplace Safety and Health (General Provisions) Regulations
(b)
The Workplace Safety and Health (Registration of Factories) Regulations
(c)
The Workplace Safety and Health (First-Aid) Regulations
(d)
The Workplace Safety and Health (Exemption) Order
(e)
The Workplace Safety and Health (Composition of Offences) Regulations
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(f)
The Workplace Safety and Health (Incident Reporting) Regulations
(g)
The Workplace Safety and Health (Risk Management) Regulations
(h)
The Workplace Safety and Health (Workplace Safety and Health Officers) Regulations
(i)
The Workplace Safety and Health (Work at Height) Regulations
(j)
The Workplace Safety and Health (Design for Safety) Regulations
Precedent to the commencement of the Works, first obtain a Certificate of Registration, under the Act
and its subsidiary legislation, The Workplace Safety And Health (Registration Of Factories)
Regulations.
It shall be the duty of the Contractor to comply with all such requirements of the Act and its
Subsidiary Legislation, as affect the Contractor or any person or persons in its employ, and as related
to any work, act or operation performed or about to be performed by the Contractor. Do not permit any
person to do anything not in accordance with the generally accepted principles of safe and sound
practice.
Ensure a safe environment on the Site at all times. All safety provisions shall be properly maintained
and shall not be removed without the written approval of the SO. Ensure that necessary and sufficient
precautions are taken by the Contractors workmen when safety provisions are used. Do not allow any
of the safety provisions to be used unless it has deemed the provision safe. Submit a safety
management system to the SO within 14 days from the date of the Letter of Acceptance for approval
prior to the commencement of the Works.
The submission of the safety management system shall comply with and be kept in the site office and
made available for reference at all times.
Display safety posters at the site office, exit/entry points of buildings and passenger cum material hoist
area.
Submit drawings, detailings and calculation for all temporary structures as required, certified by its PE,
for approval at least one week before the commencement of the Works unless otherwise specified.
The approval of the SO shall not relieve the Contractor and its PE of the need to ensure the adequacy
and sufficiency of the safety provisions.
The Contractor is deemed to have allowed in the Contract Sum for all cost and expense for the safety
provisions and for all additional costs that may arise from amendments to the Act and its Subsidiary
Legislation or changes in the requirements of MOM.
Ensure that the requirements of the Regulations and the requirements specified hereunder are strictly
complied with at all times.
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5.1.2
Metal Access Scaffold and Working Platforms
Provide, erect and maintain all metal access scaffold for all buildings other than buildings of 4 storeys
and above or 12 m in height and above. This requirement may be waived, subject to approval by the
SO, where industrialised and semi-industrialised methods of construction together with peripheral
safety nets are employed. Under such case, there shall be no adjustment to the Contract Sum. Allow
free use of the scaffold by all subcontractors, specialists, artisans and other tradesmen employed by
the Employer or the Contractor.
The metal access scaffold shall be of the type approved by the MOM. It shall comply with CP 14 and
any amendment or re-enactment thereto. The metal access scaffold shall be prezinc galvanised or
other scaffold approved by the SO.
The metal access scaffold shall be erected, or substantially extended to, or dismantled, by approved
scaffold contractor, in accordance with the Factories (Scaffolds) Regulations. The metal access
scaffold and any components therein shall be designed according to the CP14 and Workplace Safety
and Health (Scaffolds) Regulations by a PE employed by the Contractor. The metal access scaffold
shall be removed only with the permission of the SO. Submit the PEs drawings and calculations to the
SO for approval prior to the erection and dismantling. The PE shall be satisfied that his proposal shall
not duly overload the RC structure. Make the submission before the commencement of the Works.
Erect the metal access scaffold, for access and finishing work ahead of the structural work. The metal
access scaffiold shall be supported by cantilevered platforms erected in accordance with the drawings
of the PE. The cantilevered platforms shall project about 1.1 m from the edge of the building or any
other distance approved by the SO.
The material used for the metal working platform shall be pre-zinc galvanised steel and in compliance
with SS 280. The working platform shall be adequately secured to the metal access scaffold frame at the
required levels. The connections between the metal working platform and metal access scaffold frame,
and between the working platforms shall be subjected to the approval of the SO. For any portion of
the working platform where the use of metal is not suitable, timber working platform may be used,
subject to the approval of the SO. The working platform shall be complete with at least 90 mm high
coloured toeboards and metal guardrails of at least 1.1 m above the platform. The vertical distance
between any 2 adjacent guardrails shall not exceed 600 mm. Any working platform or workplace and
the guardrail immediately above it shall not exceed 600 mm. The working platform shall be at least
500 mm in width and distance between the edge of the platform shall not exceed 300 mm from
building edge
Provide, erect and maintain an overlying screening net to cover the entire external face of the scaffold.
The installation of the net shall follow the erection of the fence closely. A 90 mm high toeboard shall be
provided at the base of the net. After installation, there shall be no opening between separate sets of
the net and any torn net shall be replaced or repaired immediately. The net shall comply with the
following requirements:
(a)
Maximum mesh size: 15mm square
(b)
Twine No.: Minimum 350D
(c)
Knot type: Single or English knot
(d)
Minimum 12 ply
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The overlying screening net shall be installed on the entire external face of the access scaffold and its
installation shall follow the erection of the metal access scaffold closely. The SO shall have the right to
decide on the colour of the net all at the Contractors cost and expense.
The metal access scaffold shall be effectively tied to the building structure by means of tie- backs. All tiebacks shall be painted with a bright colour for easy identification.
5.1.3
Prefabricated Mesh Barricade
Provide, erect and maintain a vertical prefabricated mesh barricade (hereafter referred to as "mesh
barricade" for the purpose of this Clause, including all subclauses under it) for all peripheral open sides
of construction level of building (excluding multi-storey carpark/garage) where a person is liable to fall
from height. Mesh barricade shall be of sound construction and produced in the factory and installed at
the construction level from the inside of the building. Mesh barricade and its support shall be prezinc
galvanised or other approved equivalent by the SO, easily installed and dismantled, and reusable
throughout the construction (super-structure) stage. External works of the building, such as painting,
touching up works, repair and redecoration, and other minor works, shall be carried out using
mechanical suspended scaffold or other vertical access equipment.
Where the use of mesh barricade is not feasible, as interpreted by SO, during the construction (superstructure) stage, the Contractor can counter-propose localised alternative system other than the use of
metal access scaffold
Mesh barricade / counter-proposals for localised alternative system, its vertical support and any
components therein shall be in modular sizes and designed according to the WSH (Construction)
Regulations by a PE employed by the Contractor. The PEs drawings and calculation shall then be
submitted to the SO for approval within 6 weeks from the Letter of Acceptance, before installation and
use. Trial setting out of the mesh barricade shall be carried out on Site 2 weeks after approval of
submission.
The mesh barricade shall be erected ahead of the structural work (including the construction of water
tank rooms) from the second storey and held by a supporting system designed by the said PE. The
height of the mesh barricade shall be at least 1.1 m above the construction level. Together with the
PE, ensure that the substrate to which the mesh barricade is affixed to, can resist the designed
imposed loads. The PE shall satisfy himself that his proposal shall not duly overload the RC structure.
Where necessary, provide, erect and maintain an overlying screening net to cover the entire internal
face of the mesh barricade. The installation of the net shall follow the erection of the fence closely.
Where necessary, a 90 mm high toeboard shall be provided at the base of the net from the inside of
the mesh barricade. After installation, there shall be no opening between separate sets of the net and
any torn net shall be replaced or repaired immediately. The net shall comply with the following
requirements:
(a)
Maximum mesh size (square): 15 mm square
(b)
Twine No.: Minimum 350D
(c)
Knot Type: Single or English knot
(d)
Minimum 12 ply
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The vertical supports of mesh barricade shall be effectively anchored to the building structure. All
vertical supports shall be painted with a bright colour for easy identification.
The mesh barricade shall be erected according to a pre-determined safe work procedure
established by the Contractor, or substantially dismantled, by trained erectors, under the immediate
supervision of a competent supervisor. The mesh barricade and its components shall only be erected
and dismantled by workers using life-line and safety belts or other equivalent, if not better, means
of preventing a fall.
Do not use the prefabricated mesh barricade and vertical supports for other purposes.
5.1.4
Personal Protective Equipment (PPE)
Provide and maintain suitable personal protective equipment to all workmen employed at the Site.
Ensure that such personal protective equipment comply with the requirements of the Regulations.
Ensure that all equipment are properly used by (the Contractors) workmen during the course of their
work. The Contractor shall record the issuance of all equipment to the workmen.
The forms shall be kept in the site office and made available for inspection at all times. The colour
code of safety helmets provided by the Contractor shall comply with the requirements of the
Regulations. Three mirrors of sizes 600 mm x 1500 mm are to be installed for the workers to check
their personal protective equipment during Tool Box Meetings. The locations of these mirrors shall be
approved by the SO.
Provide life-lines and safety harness for workers who are required to carry out work within 2 m from any
open sides at or near the external of the building blocks, any floor or topmost construction level, lift
shafts and void areas or any other locations as directed by the SO, all at the Contractor's cost and
expense.
Approved Personal Protective Equipment (PPE) station shall be set up near the site entrance where
PPE is issued/stored.
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5.1.5
Safety (Anti-Fall) Net
Provide and maintain a safety net system to catch person(s) falling whilst working in any location from
where he/they would be liable to fall.
The safety net system shall be obtained from suppliers approved by the SO. An alternative system may
be proposed to be certified by its PE, and submitted to the SO for approval.
The safety net shall comply with SS 292 or other approved standards. The net shall be of sufficient
size and strength to catch any person for whose protection it is to be used and the net shall be so
located to cover the area of the possible fall.
Conduct a sample test on the safety net system, comprising the net and its supporting structures,
before it is installed. Subsequent tests shall be carried out when directed by the SO.
For all building blocks of 4 storeys and above, a peripheral safety net system shall be provided. Initially
the net shall be installed at the second storey. As construction progresses, reposition the net to follow
the topmost working level but keep at not more than 6.0 m below it. Remove the net only with the
approval of the SO.
Where access scaffolding is used, or any alternative safety measure approved by the SO is used, a
peripheral safety net system is not required.
The colour of the safety netting shall be approved by the SO. Safety netting of orange colour shall not
be used unless such colour is specifically decided by the SO, all at the Contractor's cost and expense.
5.1.6
Working Platforms for Lift Shafts, Central Refuse Chute and Voids
Provide working platforms, according to the design of the Contractors PE, for the erection of lift shafts
and void walls except for central refuse chute. The lift shaft and central refuse chute platforms shall
effectively cover the voids at alternate storeys.
The lift shaft, central refuse chute and void wall platforms shall be left in place until approval is given by
the SO to remove them.
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5.1.7
Protective Shelter as Overhead Shelter
Provide, erect and maintain protective shelter as overhead shelter at every point of entry/exit to
buildings of 2 more storeys height. The protective shelter shall be constructed immediately below the
second storey. It shall protrude at least 3.0 m from the building edge. It shall have a clear width of at
least 1.5 m and a clear height of at least 2.0 m as shown in the drawings. If the protective shelter is
intended for access by forklift, it shall have a clear width of at least 2.0 m and a clear height of at
least 3.0 m.
Ensure that the protective shelter rest on a rigid base. The protective shelter shall be aesthetically
pleasing, free of rust and does not trap water. The access to, along and egress from the entry/exit
points shall be kept free from obstructions and accumulation of oil, grease, water and other substances
that may cause slipping and tripping.
The protective shelter shall be strong enough to support a point load of at least 75 kg. It shall be
endorsed in accordance with the relevant statutory requirements by a PE. The PEs drawings,
detailing and calculations shall be submitted for the approval of the SO.
The protective shelter may be made of curved metal roofing with a diameter of at least 1.5m or pitched
metal roofing with a slope of greater than one in 2, with timber boarding below supported by steel
pipes.
5.1.8
Peripheral Overhead Shelters
Provide peripheral overhead shelters for buildings of more than 15 m in height. They shall be erected
in place when the construction reaches the fourth storey slab. The overhead shelter shall be at least
2 m wide and erected at a height not more than 5 m from the base of the building, and inclined so
that the outer edge is at least 150 mm higher than the inner edge. The overhead shelter shall be
sufficiently strong to support a weight of at least 75-kg point load.
5.1.9
Barricades to Lift Openings, Voids, The Open Sides of Buildings and Excavations
Barricade all lift openings, internal voids and the open sides of buildings and excavations where a
person is liable to fall. The barricade shall be at least 1.1 m high with 90 mm high toeboard and shall
have sufficient strength and rigidity to withstand a lateral point load of 50 kg. All services openings
shall be fully covered and secured to prevent unauthorised removal.
5.1.10
Mechanical Suspended Scaffold
Mechanical suspended scaffold system shall only be used for touching up, repair and redecoration and
minor work. Where mechanical suspended scaffold system is to be used, first obtain a Certificate of
Registration under the Workplace Safety and Health Act from MOM and a written approval from the
SO prior to its installation and usage. The mechanical suspended scaffold system shall comply with
the requirements of the SS 598 and any amendment or re- enactment thereto. Where the use of
access scaffolding is not stipulated, suspended scaffold may be used for finishing works. Provide lifelines for the mechanical suspended scaffold users to anchor their safety belts.
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5.1.11
Authorised Operators for Machinery and Vehicles
Employ only qualified operators for its site machinery. The operator for the machinery shall possess a
Skill Evaluation Certificate (SEC) from the BCA Academy or other approved training centre. For the
machinery whereby BCA Academy or other approved training centre does not conduct courses or
practical tests for machinery operator, only authorise an experienced and trained operator who has at
least a minimum of 2 years experience in operating the machinery.
In the case of vehicles, which are operated within the Contract boundary, the authorised operator shall
possess a minimum valid Class 3 driving licence from the Registrar of Vehicles (Singapore) or its
equivalent. The equivalent of a minimum Class 3 driving licence shall first be verified by the respective
embassy in Singapore and thereafter submitted to the SO for approval.
Record the particulars of the operators for the machinery and vehicles in the prescribed form and
submit to the SO for approval 1 week before the commencement of the Works. The prescribed form
shall be updated and kept on the Site and made available for inspection at all times.
5.1.12
Safety Training
5.1.12.1
Safety Orientation Course
Employ workmen who possess valid Safety Orientation Course Certificates. The Contractor shall be
required to ensure that its workmen attend a prescribed safety refresher course at an interval of time
decided by the SO.
5.1.12.1
Safety Training Course
When directed by the SO, send employees/staff in the Contractors employ to MOMs accredited training
providers for the appropriate safety trainings. The safety training shall be applicable to all levels of
employees/staff stipulated in this subclause including top management at the site.
Give particular attention to the needs of young employees/staff. Further training shall be required
where:
(a)
Employees/staff are transferred or where employees/staff take on new responsibilities or where a change
in the work activity or work environment could arise; and
(b)
There is a change in the work equipment or systems of work in use.
Training shall be repeated periodically to ensure continued competence.
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5.1.13
Tower Cranes and Other Tall Construction Equipment
Comply with all height restrictions on the use of tower crane or other tall construction equipment,
imposed by the Civil Aviation Authority of Singapore and Ministry of Defence. In addition, the height
clearance of tower crane or other tall construction equipment shall be submitted to the SO for
approval before they are brought to the Site. Force limiting device, speed limiters and moment limit
switches shall be installed for all cranes.
Submit detailed layout drawings and safety requirement of the tower cranes to MOM and the SO for
approval at least one month prior to their installation. The Safety Factor for tower crane shall have a
minimum of 1.3, which includes the built-in factor of safety for the tower crane. The lifting load shall
include the weight of the component, the spreader beam and the lifting device. The tip-load shall have
the capacity to hoist the heaviest component including the necessary lifting appliances. The slewing
radii of the tower cranes shall not overlap, unless the tower cranes are equipped with an anti-collision
system. It is not permitted to be hoisted over temporary building structures, outside the contract
boundary and other sensitive areas. The slewing limit switch shall be activated to stop the slewing
action before the jib slews into the overlap zone.
The jib of a tower crane shall not be allowed to slew outside the Contract boundary lines without the
written approval of the SO. The free-standing mast of the tower crane must be certified by the
Contractor's PE prior to its use on the Site.
Submit detailed drawings and calculations of the type of foundation support and the tie-back for the
tower crane, duly endorsed by its PE, together with technical information to the SO for approval. The
Contractor's PE shall certify that the free-standing height of the mast is structurally adequate and
sound before the tie-back is installed. No tower crane shall be installed and supported on the
constructed RC structure of a building.
5.1.14
Access for The Use of Mobile Crane and Piling Machines Next to Built-Up Area
Where the Contractor uses mobile cranes and piling machines on the Site which is next to existing
buildings or public roads or MRT lines, the access for the mobile cranes and piling machines shall
be of steel plates or reinforced concrete or bituminous pavement as approved by the SO. All such
access shall be provided over adequate compacted hardcore base.
Provide full access for the movement of the cranes and piling machines and for their lifting or pile driving
operations. The access shall be able to distribute the load so as not to exceed the bearing capacity of
the underlying materials.
Engage a PE to design the access. The drawings and calculations endorsed by the PE shall be
submitted for approval by the SO before the construction of the access. The access shall be
constructed according to the approved drawings and maintained in a good condition at all times
throughout the Contract Period (including any extension thereof). The access shall be inspected by the
Contractor's PE prior to its use.
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5.1.15
Warning Signs and Lights
Display warning signs of size 900 mm x 600 mm at strategic points around the periphery of the Site
where trespassing is likely to occur. Such signs shall have the words "DANGER KEEP OUT" in the 4
official languages in red on white background with reflective material and approved by the SO.
Warning lights shall be placed at similar positions at night to serve as a warning.
If work is carried out near public roads, all signage shall comply with the recommendations of the
Temporary Road Signage Manual issued by the LTA.
5.1.16
Mobile Crane
Submit layout and details of the crane access to the SO for approval prior to the use of the crane on
the access. Ensure and check that the crane access is properly constructed. Keep all records of
inspections of the crane access at the Site and produce them for examination when requested by the
SO. The boom of the mobile crane with hoisted load shall not be allowed to swing outside the
contract boundary without the written approval of the SO. All hoisting areas must be effectively
barricaded.
Ensure the installation of barriers to warn the crane operator of depressions, excavated areas and
other obstructions.
Moment limiters shall be installed for all cranes. The safety factor for mobile crane shall have a minimum
of 1.3, which includes the built-in factor of safety for the mobile crane. The lifting load shall include the
weight of the component, the spreader beam and the lifting device. The tip- load shall have the
capacity to hoist the heaviest component including all necessary lifting appliances. A Permit-To-Hoist
must be obtained before any hoisting operation is carried out.
Station a lifting supervisor on the Site to oversee and guide the crane operator during positioning,
hoisting and slewing. The cranes shall be tested by an AE before its use on the Site irrespective of any
valid test certificate. Ensure daily checks are carried out by the crane operator and maintenance
checks conducted once every 3 months. The crane must have overhaul checks before it is used on
the Site. Test certificate, overhaul certificates, maintenance certificates, inspection records by the crane
operator, data on the AE and the Contractor's site engineer shall be properly documented, kept on the
Site and produced for inspection by the SO.
5.1.17
Crane Operator, Lifting Supervisor, Rigger and Signalman
Comply with the Workplace Safety and Health (Operation of Cranes) Regulations 2011. Appoint at least
one full-time lifting supervisor to supervise all lifting operations of any crane for the Site. However,
where more than one crane is used on the Site, the number of lifting supervisors employed by the
Contractor shall be increased as required by the SO. No lifting activity shall be allowed without the
supervision of the lifting supervisor.
The lifting supervisor shall have a minimum of 3 years experience in construction work and lifting
operations. He must be a site foreman or site engineer and possesses a certificate on Safety
Instruction Course for Lifting Supervisor. He shall spend his time fully on all lifting activities and ensure
that unsafe conditions are rectified.
For lifting operations within the Site not next to existing buildings, public roads or MRT lines, the crane
operators shall have a minimum of 2 years experience in the operation of cranes.
The Contractor can employ crane operators with less than 2 years experience for lifting operations on
site but subject to the following conditions and approval by the SO:
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(a)
The site must be situated in a non-built-up area and not next to existing buildings, public roads or MRT
lines.
(b)
The crane operator shall be enrolled for the BCA Building Specialist Sponsorship (Crane Operations)
programme at the On-the-Job Training (OJT) stage and be subject to the passing requirement of the
programme.
(c)
Other measures as and when instructed by the SO, including the removal of such crane operator if the
crane operator is found to be not operating the crane in a safe manner.
Notwithstanding other provisions within this Clause, the employment of such crane operator will not
subject the Contractor to cost omission.
The Contractor can also employ apprentices from BCA Building Specialist Sponsorship (Crane
Operations) programme for lifting operations on site but subject to the following conditions and approval
by the SO:
(d)
The site must be situated in a non-built-up area and not next to existing buildings, public roads or MRT
lines.
(e)
Contractor and crane supplier shall brief the Employer and Consultants on the risk assessment and
control measures prior to deploying an apprentice on Site.
(f)
Tower crane is preferred to be sited on the inner side of building so that the building acts as a buffer.
(g)
Cranes collapse zone must not overlap with existing buildings or public facilities when it is free standing.
(h)
Apprentice shall operate the crane from the beginning of the construction. In the first few months, he will
get used to the crane without involving heavy lifting of precast components.
(i)
Apprentice can only operate in the same crane on site till project completion and not allowed to switch
crane.
(j)
Apprentice shall not operate in a crane serving a building under construction with storey height exceeding
25 storeys.
(k)
Apprentice shall pass a competency assessment under the BCA Building Specialist Sponsorship (Crane
Operations) programme before being allowed to lift heavy precast components for installation.
(l)
A maximum of one apprentice can be employed on each site.
(m)
Other measures as and when instructed by the SO including the removal of the apprentice if the
apprentice is found to be not operating the crane in a safe manner or/and not complying with the safety
measures listed above.
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Notwithstanding other provisions within this Clause, the employment of apprentices from the BCA
Building Specialist Sponsorship (Crane Operations) programme will not subject the Contractor to cost
omission.
For lifting operations within a site which is next to existing buildings, public roads or MRT lines, the crane
operators shall have a minimum of 5 years experience in crane operation.
Nevertheless, upon the approval of the SO, the Contractor is allowed to employ crane operators with
a minimum of 3 years experience in crane operation instead but shall subject to the following conditions
and approval by the SO:
(n)
The crane operators shall pass an assessment by BCA on their competency.
(o)
The Contractor shall carry out risk analysis based on the positions of the cranes to decide which cranes
would be suitable for deploying such crane operators. Generally, this means that such operators should
operate tower cranes that are at least 50 m away from any existing buildings and facilities, and the
collapse zone of the crane does not overlap with existing buildings.
(p)
Other measures as and when instructed by the SO.
(q)
Riggers and signalmen shall also be appointed for all lifting operations and they must have completed an
approved training course.
(r)
The crane operator, lifting supervisor, rigger and signalman shall carry out their duties strictly according to
the relevant regulations and other duties as the SO deems necessary from time to time.
Submit a list of crane operators, lifting supervisors, riggers and signalmen with their names,
identification card or passport numbers, qualifications and years of experience to the SO for approval
1 week before the use of the crane. The list shall be updated and kept on site at all times. The SO
reserves the right to examine the list as and when required.
5.1.18
Temporary Staircases
Provide and maintain 0.8 m minimum wide temporary metal staircases from one working floor to
another. Place the staircases against the adjacent staircase walls or formwork of the staircase walls
that are under construction. Provide the outer sides of the staircases with metal handrails 1.1 m above
the outer staircase strings. The bottom of the staircases shall be covered fully with metal plate.
Engage a PE to design the staircases. Submit the PEs drawings, details and calculations for approval
by the SO before the construction of the staircases.
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5.1.19
Gas Cylinders and Related Equipment
Use gas cylinders fitted with a low pressure gauge and a high pressure gauge, a reducing valve with
pressure regulator, and safety relief device. The gas cylinders shall not be kept in the same room
where welding, cutting or heating is being carried out or placed within 5 metres of any source of heat.
The gas cylinders must always be kept upright in a wheeled-trolley.
The hose connecting a gas cylinder to an apparatus for cutting, welding, heating or other related
works shall be of good construction and sound material, free from defect, properly maintained, and
not entangled or kinked.
A flashback arrester or any other similar device which stops flashback that is acceptable to the
Commissioner for Workplace Safety and Health must be fitted at every outlet of a gas cylinder and every
inlet of an apparatus.
The gas cylinders and hoses shall be colour-coded to conform to SS 152: Specification for Identification
of Contents of Industrial Gas Cylinders or any amendments thereof.
Engage a competent person to check the safety devices referred herein once in every 6 months. The
competent person is any person who is competent by education, training and experience on the safety
and operational aspects of the use of gas cylinders and related equipment.
5.1.20
Socket Outlet Assembly
Provide, install and maintain the socket-outlet assembly (hereinafter referred to as "SOA" for the
purpose of this subclause) for all temporary electrical installations. The SOA shall be manufactured
in accordance with the latest edition of SS 650-1. It shall be designed for wall mounting or fitted
with castors so that it can be moved around on the Site. Every electrical equipment used shall be
plugged directly into the industrial SOA.
5.1.21
Others
Provide and maintain guards or fences or barriers around excavations, lift pits or other similar potential
places of danger to prevent accidents. The guards, fences and barriers shall be of sound material,
good construction and possess adequate strength.
At the site entrance gate, provide a gantry fitted with a height control device and a siren to control the
height limit of construction vehicle/machinery when the vehicle/machinery leaves the Site. This limit
shall comply with the requirements of LTA.
The Contractor shall provide and maintain storey number indicators of size 400 mm x 400 mm at
every staircase area and 900mm x 900mm at the metal scaffold enclosing passenger cum material
hoist. The indicators shall be displayed at alternate storeys starting from the second storey.
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5.2
Safety Infringement
Include in the Contract Sum for all costs and expenses for complying with the safety requirements.
The SO shall conduct periodic inspections on the provision of safety measures with the Contractor's
site safety supervisor or the Contractor's Representative. The Contractor shall rectify immediately any
contravention of or non-compliance with the Workplace Safety and Health Act and its Subsidiary
Legislation, Workplace Safety and Health (Construction) Regulations or safety measures specified. All
Works or part of the Works may be stopped when the SO considers the working environment or
procedure is unsafe for Works to continue. In such event, the SO may invoke the provisions of Clause 6
"Nuisance and Irregularities" and the Contractor shall not be entitled to any claims for compensation or
extension of Contract Period.
If the contravention is not rectified by the subsequent inspection, the SO may invoke the provisions of
the clause on "Nuisance and Irregularities".
Upon any accident or dangerous occurrence, occurring on site, the SO, the Employer or any Competent
Authority may order a total or partial stoppage of the Works, depending on the nature and extent of the
accident/dangerous occurrence, to allow for investigations and/or to carry out remedial measures.
Under such cases, the Contractor shall not be entitled to any claims for compensation or extension of
Contract Period.
The SO may, at its absolute discretion, also invoke the provisions of Clause 6 "Nuisance and
Irregularities" for the following type of incidents occurring in the course of or arising out of or in
consequence of the Works:
(a)
Fatal accident, if the SO or Competent Authority is of the opinion that the accident is the result of the
defaults, acts, omissions or negligence, in part or in whole, of the Contractor.
(b)
Other accident which the SO, the Employer or Competent Authority is of the opinion that the accident is
the result of failure of the Contractor to provide necessary and sufficient safety measures stipulated in
the Contract or the Workplace Safety and Health Act and its Subsidiary Legislation, the Workplace Safety
and Health (Incident Reporting) Regulations.
(c)
Dangerous occurrence as classified in the Subsidiary Legislation, Workplace Safety and Health (Incident
Reporting) Regulations, Part II if the SO, the Employer or the Competent Authority is of the opinion that
the dangerous occurrence is the result of failure of the Contractor to provide necessary and sufficient
safety measures stipulated in the Contract or the Workplace Safety and Health Act and its Subsidiary
Legislation, the Workplace Safety and Health (Incident Reporting) Regulations.
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5.3
Reporting of Accidents and Dangerous Occurrence
In the case of an accident or dangerous occurrence as classified under the Workplace Safety and
Health (Incident Reporting) Regulations, the Contractor shall notify the Employer and relevant
Authorities within one hour of an incident. After being informed of it, the SO or the Employer may at
his discretion make a preliminary investigation of the circumstances and record its findings.
Notwithstanding the aforementioned requirements, make an incident investigation and prepare/submit
an incident investigation report to SO and the Employer within 10 days of the incident. Upon submitting
this report, arrange for the injured workman, witnesses and an interpreter, if necessary, to report to SO
to furnish evidence relating to the incident.
If the Contractor fails to give any required notice or fails to furnish evidence of the incident as required in
this Clause, the SO may at his discretion invoke the provisions of Clause 6 "Nuisance and
Irregularities".
6
NUISANCE AND IRREGULARITIES
6.1
Irregularities
If the Contractor is found to have committed any of the following irregularities:
(a)
Omitting building materials or labour, reducing the sizes of the materials, using inferior materials; or
materials constructed not according to the Specification or Drawings;
(b)
Creating nuisance at the Site thereby causing inconvenience to the SO or the public or committing
similar acts (such as not complying with site safety requirements, etc.) which are likely to bring the
Employer into disrepute;
(c)
Non-compliance with any part of the Specification or Drawings, or non-fulfilment of any contractual
obligation.
The SO or Employer is empowered to respond in one the following ways:
6.2
(i)
Order any irregular work to be removed and made good to the satisfaction of the SO or
Employer at the Contractor's own cost and expense.
(ii)
In lieu of correcting work not done in accordance with the Contract, the SO or the
Employer may allow such work to remain and shall recover any cost differences between
the specified requirements and the non- compliance.
Nuisance
For nuisance committed on the Site, take immediate action to cease the nuisance committed upon
instruction given by the SO or Employer.
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7
SPECIAL CONDITIONS ON SURVEY WORKS
7.1
General Requirements for Land Survey Services
The Contractor shall engage a registered surveyor at its own cost and expense to provide Land Survey
Services to facilitate construction works and to carry out surveys for record purposes or for submission
to authority as and when requested by the SO during construction and post construction stage.
The cost incurred shall include the purchase of information and any equipment required for the survey
works. The Contractor shall be held fully responsible for the accuracy of all the survey works carried out
by its Registered Surveyor and for ensuring the Works fully comply with the following:
7.1.1
(a)
Technical requirements and standards in the conduct of the surveys as specified in the latest version of the
land surveyors board directive on engineering and hydrographic survey practices.
(b)
Technical requirements and standards in the conduct of the surveys as specified in the latest Singapore
Land Authority (SLA) directive on cadastral survey practices;
(c)
Circulars that are issued from time to time by the Chief Surveyor, Singapore, SLA.
(d)
A field works and office works are executed by the Registered Surveyor or qualified staff under the
registered surveyor direct supervision and direction.
(e)
All documents and survey works pertaining to the survey are certified and dated by the registered
surveyor supervising the survey.
(f)
Latest SLAs Standard and Specification for 3D Topographic Surveying (Mapping) in Singapore
For Projects with Contract Sum of $50 Million and more
For projects with contract sum of $50 million and more, the Contractors Resident Surveyor or Lead
Surveyor performing land surveying works on site must be a registered Technical Member of Singapore
Institute of Surveyors and Valuers (SISV) from 1 Jan 2017 onwards.
7.2
Pre-condition Survey
Where applicable, prior to and upon completion of the Site Works, carry out a condition survey to
adjacent buildings in accordance with the requirements of Section C01-020 "Condition Survey".
Submit all records to the SO and adjacent property owners where directed. The influence zone due
to the excavation works with the sheet piles as support system shall be according to BCA
requirement. Keep a copy of the survey report on site ready for inspection.
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7.3
Engineering Survey Services (Construction Stage)
All forms of land survey services required for the purpose to facilitate the construction works or survey
works requested by the SO in relation to the construction of the projects shall be performed by the
Contractors Registered Surveyor. Such surveys shall include the following:
(a)
Setting out of parcel boundaries, grids, piles position, building blocks, minor sewer and service roads
alignments, etc.
(b)
Piles eccentricity checks survey.
(c)
Topographical survey of surrounding services and roads.
(d)
As-built survey of services and preparation of setting out plans, cross-sectional and longitudinal plans and
surveys to monitor ground settlement, where applicable.
(e)
Last inspection chamber/sewer manhole.
(f)
SPPG electrical substation
The Registered Surveyor engaged by the Contractor to prepare the pre-computation plan shall ensure
the approved pre-computation plan tallies with the Consultants drawings. The Contractor receiving the
approved pre-computation plan shall also check that it tallies with the Consultants drawings. Prior to the
setting out of the piles position, the Contractor shall ensure that the distance between the piles position
and the parcel boundary, the distance between the piles position and the building block, and the
distance between the piles position and the gridlines are according to the Consultants drawings.
7.3.1
Additional Site Investigation
Carry out additional ground investigation where additional information is needed for the Works or when
directed by the SO. Carry out the Works in compliance with Section C02-010 "Ground Investigation"
and BCA requirement.
The permeability, strength of the subsoils and the groundwater level are key design parameters to be
ascertained to determine the required penetration depth of the sheet pile wall to ensure overall
stability and seepage cut-off.
Carry out the boreholes pregressively, prior to commencement of the Works in areas according to the
Contractor/s contruction programme. On completion of drilling, backfill the boreholes with a suitable
bentonite/cement mix.
Submit the location and schedule for the boreholes to the SOs acceptance prior to carrying out the
Works. On completion, prepare the site investigation report and submit to the SO for acceptance.
The Contractor shall report immediately to the SO any circumstance which indicates that in the
Contractors opinion, the ground conditions differ from those reported in or which could have been
inferred from the subsurface investigation reports.
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8
CONTRACTOR TO VISIT SITE
The Contractor shall be deemed to have taken note of all conditions for the construction and
completion of the Contract, in particular, the following conditions pertaining to this Contract and satisfy
itself on and make provision in the Contract Sum:
(a)
The nature of sites and soils both above and below ground with respect to various stages of construction in
particular the possible existence of boulders/granite underground and other buried materials which have
to be removed from site.
(b)
The provision of temporary access for traffic diversion while work is in progress to ensure undisrupted
movement of traffic at all times.
(c)
The effect of existing properties, building structures / foundations.
(d)
The availability, supply of and conditions affecting labour within the Contract Period.
(e)
The effect of other contractors or persons approved by the SO, working within the contract area.
(f)
The probable adverse effect of the weather on the execution of the Contract.
(g)
The effect of execution of works due to the presence of hard soil strata, existing services, etc.
(h)
The means of access to facilitate the transportation and movement of construction equipment.
(i)
The general ground levels, spot levels of the work site.
(j)
The provision of earth drains; silt traps and the requirements to deal with drain diversion.
(k)
All aspects of local conditions, physical or otherwise, at the site that pertains to or affects in any way the
construction works required at the Site concerned.
(l)
The effect of encountering various existing cables, pipes, sewers, etc. which may require diversion.
(m)
The effect of heavy vehicular and pedestrian traffic.
(n)
The necessary re-instatement of all affected turfing areas and works affected by this contract.
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The Contractor must also ascertain for itself the most convenient and expeditious method of carrying
out the Works. The working conditions and the space to be made available as a work site should be
inspected and no claims shall be allowed on the ground of lack of knowledge of the conditions under
which the work will be executed.
The Contractor shall note that all information regarding existing levels given in the drawings only
serves as a guide and it shall obtain its own information whenever it is doubtful.
No claim by the Contractor for additional payment will be allowed on the ground of any
misunderstanding or misinterpretation in respect of any such matter nor shall the Contractor be released
from any risks or obligations imposed on or undertaken by itself under the Contract on any such ground
or on the ground that it did not or could not foresee any matter which might affect or have affected the
execution of the Works.
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(2) C01-010 Demolition and Site Clearance
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1
GENERAL
Read this Section with G01-010 "General Requirements" and all other contract documents.
1.1
Scope
This Section covers the requirements for works involving the demolition of existing buildings and other
structures and general site clearance. The scope of demolition works and particular requirements are
as indicated and shown in the drawings.
[Note 1: The drawings should specify and indicate particular requirements relating to and information
about the existing structures, restrictions on working methods, constraints imposed by the permanent
works, etc. If there are particular phasing requirements due to either structural issues or
access/availability, these must be adequately described, similarly occupied premises.
Requirements for partial demolition should be fully described.
Identify in the drawings if the works are within the MRT Protection Zone.]
1.2
Related Sections
Read this Section in conjunction with the relevant requirements of the following sections:
1.3
C01-020
Condition Survey
C02-020
General Earthworks (Excavation and Filling)
C02-050
Instrumentation and Monitoring
Standards, Codes, Regulations and Technical References
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1.3.1
Standards and Codes
Unless otherwise agreed by the SO, ensure all of the Works comply with the relevant requirements of
the Standards and Codes listed below or referenced in the body of the Specification. Alternative
Standards and Codes may be proposed for approval by the SO, provided it can be demonstrated that
the alternative Standards and Codes comply with the requirements of the standards specified. All
Standards and Codes quoted are the current version, unless specific year references are noted.
In the event that the Standards or Codes are partially superseded or become obsolete, refer to the
latest edition or the approved substitution for the relevant clauses.
Singapore Standards
NA to SS EN 1991-1-4
Singapore National Annex to Eurocode 1: Actions on Structures - Part 14: General actions - Wind actions
SS CP 14
Code of practice for scaffolds
SS CP 20
Code of practice for suspended scaffolds
SS CP 49
Code of practice for noise control on construction and demolition sites
SS 280-1
Specification for metal scaffoldings - Part 1: Frame scaffoldings
SS 280-2
Specification for metal scaffoldings - Part 2: Modular scaffoldings
SS 557
Code of practice for demolition
SS 568
Code of practice for entry into and safe working in confined spaces
SS 580
Code of practice for formwork
Other Standards
BS EN 1808
Safety requirements on suspended access equipment - design
calculations, stability criteria, construction - test
BS EN 12811-1
Temporary works equipment. Scaffolds. Performance requirements and
general design
BS EN 12812
Falsework - Performance requirements and general design
BS 5228-1
Noise and vibration control on construction and open sites - Part 1: Code
of practice for basic information and procedures for noise and vibration
control
BS 5395-1
Stairs, ladders and walkways - Part 1: Code of practice for the design
construction and maintenance of straight stairs and winders
BS 5607
Code of practice for safe use of explosives in the construction industry
BS 5974
Temporary installed suspended scaffolds and access equipment
(partially superseded by BS EN 1808)
BS 5975
Code of practice for falsework
BS 6187
Code of practice for demolition for full and partial demolition
[Note 1: SS 557 and BS 6187 provide detailed guidance on matters relating to demolition.]
1.3.2
Regulations
Unless otherwise specified, the Works shall comply with the relevant sections of the following statutory
requirements:
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1.4
(a)
Workplace Safety and Health Act
(b)
Workplace Safety and Health Guidelines - Management and Removal of Asbestos
(c)
Workplace Safety and Health (Scaffolds) Regulations
(d)
Asbestos Hazards in Building Work Involving Old Buildings, MOM
(e)
Revised Regulations to Enhance Protection of Workers from Asbestos Exposure, MOM
(f)
Workplace Safety and Health (Medical Examinations) Regulations 2011
(g)
Requirements for medical monitoring, MOM
(h)
Building Control Act and Regulations
(i)
Environmental Protection and Management Act, NEA
(j)
Environmental Public Health Act, NEA
(k)
Environmental Pollution Control (Air Impurities) Regulations
(l)
Code of Practice for Railway Protection, LTA
(m)
Guide to Carrying Out Restricted Activities within Railway Protection and Safety Zones, LTA
(n)
Fire Safety Act;
(o)
Fire Safety (Building Fire Safety) Regulation;
(p)
Not In Use
S(p)
SCDF Code of Practice for Fire Precautions in Buildings.
(q)
PUB (Earth COntrol Measures)
(r)
Code of Practice of Sewerage and Sanitary Works
Trade Preamble
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1.4.1
Contractor’s Submissions and Proposals
Propose and submit for SOs acceptance method statement that shall include sequence and method of
demolition, protective measures and equipment for the demolition.
Do not vary methods on site from the agreed method statement without prior approval by the SO.
Notify the SO any proposed variations to the method statement within 14 days unless otherwise
agreed.
Propose as a response plan in the event that measures taken to control ground movement and vibration
do not perform satisfactorily.
1.4.2
Engineering Design and Calculations
1.4.2.1
General
Engage a suitably qualified, experienced and competent PE and other qualified and experienced
personnel to prepare all drawings and calculations for the following works:
1.4.2.2
(a)
Temporary support structures
(b)
Temporary hoarding
(c)
Scaffolding and staging
Professional Engineer
The responsibilities of the PE include the following:
1.4.2.3
(a)
Planning of sequence of installation and dismantling
(b)
Assessment of the structural integrity of existing property and abutting property
(c)
Design of temporary vertical and lateral supports to prevent uncontrolled collapse
(d)
Design to control ground water and provision of temporary drainage
(e)
Assessment of construction loadings permitted on existing structure
(f)
Submission of all calculations to BCA for approval as required under the Building Control Act and to the
other authorities for record.
(g)
Supervision of the demolition work in accordance with the Building Control Act and Regulations
Temporary Hoarding
Design the temporary hoarding to withstand all imposed loads due to wind, crowds and impact, where
applicable, and to provide protection to workers and the public.
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1.4.2.4
Scaffolding and Staging
Provide PE’s endorsement when the scaffolding and staging works exceeds the following criteria:
(a)
The deck is more than 3 m above ground.
(b)
The deck carries an intensity of loading higher than 1.5 KN/m2.
(c)
The staging is more than 3 tiers.
1.4.3
Supervision
1.4.3.1
Demolition
Engage a full-time qualified and competent supervisor with suitably experienced in demolition to
supervise the work strictly in accordance with the directions of the PE engaged for the
responsibilities as provided in Section C01-010: Clause:1.4.2.2.
A competent supervisor shall have sufficient professional or technical training, knowledge and actual
experience to enable them to:
1.4.3.2
(a)
carry out their assigned duties at the level of responsibility allocated to them.
(b)
understand fully any potential hazards related to the work under consideration.
(c)
detect any technical defects or omissions in that work, recognise any implications for health and safety
caused by those defects or omissions.
(d)
be able to specify a remedial action to mitigate those implications.
Scaffolding and Staging
Engage a registered scaffold erector to supervise the erection of all scaffolding and staging in compliance
with Workplace Safety and Health (Scaffolds) Regulations.
1.4.4
Qualifications
Provide evidence of past experience for all personnel to the SO for acceptance prior to commencement
of the Works.
1.4.5
Verification of Information
Obtain from the SO and verify available information relevant to the following:
(a)
Existing site surveys
(b)
Existing services
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(c)
Existing building on the Site
(d)
Site or ground investigation
Carry out additional investigation or request from the Authorities to ensure that adequate information is
available to carry out the Works.
Allow for conditions peculiar to the site and all other matters affecting the proposed Work and allow as
necessary for the types of materials to be excavated.
1.4.5.1
Existing Site Surveys
Engage a Registered Surveyor to carry out or, if given, to verify the survey prior to commencement of the
Works.
1.4.5.2
Existing Services
Comply with all the statutory requirements in respect of the existing services at and around the vicinity of
the Site.
Terminate or divert all relevant existing services as required by the authorities prior to commencement of
the Works.
Obtain information on the existing services, including services to private properties. Verify actual sizes
and locations of all services and mark on site prior to commencement of the Work.
Conduct under ground services detection. Propose suitable method to the SO for acceptance.
Mark type and depth of under ground services with signboards and overhead services with headroom
markers. Inform the authorities any services encountered on site.
[Note 1: Details of retained features and under or above ground live services should be provided.
Include where appropriate their shut-off points. This information should be given on drawings. It is
important to be clear that information from the authorities will be approximate only and will not cover
property connections etc. Check the contract preliminaries and other sections for clauses that may give
conflicting or duplicated information.]
1.4.6
Condition Survey
Prior to and upon completion of the site works, carry out a condition survey to adjacent buildings in
accordance with the requirements of Section C01-020 "Condition Survey". Submit all records to the
SO and adjacent property owners where directed.
Keep a copy of the survey report on site ready for inspection.
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1.4.7
Instrumentation and Monitoring
Provide instrumentation to monitor the ground movement, vibration and condition of adjacent properties.
Refer to Section C02-050: Clause:3.1, and the drawings for the schedule of instrumentation required. If
necessary or as required by the authorities, propose and provide additional instrumentation and
monitoring for records.
Take cognisance of and co-ordinate with other contractors on site who may be carrying out
instrumentation and monitoring works to avoid duplication of installation and readings.
For general requirements of the instrumentation and monitoring works refer to Section C02- 050
"Instrumentation and Monitoring".
1.4.8
Upholding of Adjoining Properties
Accept responsibility for the upholding of the adjoining buildings and roads, footpaths etc., where
applicable, together with the mains and services from the time of taking possession of the Site
through the duration of the Works.
Adequately maintain roads and footpaths within and adjacent to the Site and keep clear of mud and
debris.
1.4.8.1
Weatherproofing of Adjoining Buildings
Allow for the weatherproofing of any surfaces of the adjoining buildings that are exposed by the
demolition as required.
[Note 1: Where it is required, the form and life expectancy of the weatherproofing should be specified and
agreed, if appropriate, with the owners of the adjacent building.]
1.4.9
Site Safety
1.4.9.1
General
Do not permit any person to do anything not in accordance with the generally accepted principles of
safe and sound practice.
Ensure a safe environment on the Site at all times. Maintain all safety provisions properly and do not
remove any specific equipment, etc., without the written acceptance of the SO.
Ensure that all personnel take necessary and sufficient safety precautions.
1.4.9.2
Legislation Compliance
Site safety shall comply with the WSH Act and its subsidiary legislations, including WSH Regulations and
Code of Practices issued by the Workplace Safety and Health Council.
Obtain a Certificate of Registration under the WSH Act, and the necessary permits and approvals
under the Building Control Act and Regulations prior to the commencement of the Works.
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1.4.9.3
Site Safety Supervisor
Employ a site safety supervisor with a recogniszed and approved certification in construction safety on
full-time basis throughout the duration of site works.
The responsibilities of the site safety supervisor include the following:
1.4.10
(a)
To supervise safety and promote safety conduct
(b)
To inspect and rectify any unsafe place of work
(c)
To correct any unsafe practice
(d)
To ensure compliance with the provisions of the WSH Act and its subsidiary legislations
Temporary Access Roads
Submit the proposed alignments and levels of temporary access roads to the SO for acceptance
prior to commencement of the Works.
Maintain all necessary temporary access roads with drainage ditches over their full length. Divert
and reinstate the permanent drainage system.
1.4.11
Temporary Access Stairways and Walkways
Provide temporary access stairways and walkways in compliance with BS 5395-1, particularly with
respect to minimum headroom and clearance, both vertically and perpendicular to the plane of the
stairs.
1.4.12
Temporary Works
Erect all temporary structures in strict compliance with the PE's design.
1.4.13
Temporary Hoarding
1.4.13.1
General
Erect protective hoarding, safety netting/catch platform or other structures to ensure public safety prior to
starting demolition works.
Provide, erect and maintain a continuous hoarding around the entire contract boundary prior to
commencement of the Works.
Erect the hoarding at not less than 300 mm away from any permanent structure such as footway,
drain, pipeline, etc., unless otherwise agreed.
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1.4.13.2
Type of Hoarding
The types of hoardings to be erected depend on the building locality and the demolition zone. In
general, the categories of hoarding shall be as follows:
Category A: Protective hoarding for use where footway is needed. Category B:
Protective hoarding for use where footway is not needed. Category C: Protective
hoarding erected on carriageway.
Category D: Scaffold hoarding shall be minimum 6.8 m high where the distance between the building
edge and the hoarding is less than 1½ times the height of the building.
Category E: Metal hoarding shall be minimum 2 m high where the distance between the building
edge and the hoarding is more than 1½ times the height of the building.
Provide the categorty type of hoarding as indicated and specified in the drawings or as directed by the
SO. Unless agreed by the SO, the hoardings shall be in accordance with SS 557.
1.4.13.3
Access Locations
Provide metal gates/doors with minimum and maximum height as indicated in the drawings for the
main and side entries located at approved positions. There shall be a maximum of 2 entry points for
the entire site unless otherwise agreed.
1.4.13.4
Hoarding Decoration and Signage
Maintain the hoarding and gates at all times to ensure no deterioration of the structure and fading of
the paint works throughout the duration of the Contract.
Display "DANGER", "KEEP-OUT" and "NO TRESPASSING" signs in the 4 official languages at
conspicuous locations on the exterior side of the hoarding.
Paint such signs in red and white background with gloss finishing enamel paint.
1.4.13.5
Project Signboard
Where required, incorporate project signboard according to architectural drawings as part of the
hoarding.
1.4.14
Site Inspection
Visit and inspect the Site to understand the conditions and characters of the Works and to ascertain the
exact position and full extent of the Works.
1.4.15
Demolished Material
Take possession of all demolished material and hand over those identified in the drawings or as
directed by the SO.
Dispose all debris at NEA approved tips. Take special care to prevent debris from site being
carried or blown onto surrounding areas. Clean vehicle wheels before the vehicle leaves site.
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1.4.16
Rubbish
Take all reasonable steps to minimise waste production on site.
Dispose rubbish and unwanted non-hazardous materials at NEA approved tips and keep the site
clean and tidy.
Remove all rubbish, dirt and residues from voids and cavities before filling or closing in.
Sort and dispose of recyclable materials at an NEA approved Material Recycling Facility where
applicable.
Retain waste transfer documentation on site.
1.4.17
Burning on Site
Do not permit burning of materials.
1.4.18
Reinstatement and Making Good
1.4.18.1
General
Avoid damage to existing structures, pavements and properties.
Reinstate and make good any damage caused by or as a result of the Works. Reinstatement and
making good shall also include all affected fixtures, fittings and finishes.
1.4.18.2
Consent
If it is found necessary to break up existing pavement, road, footpath, etc., for purposes as required in the
Contract, notify the SO accordingly prior to commencement of Works.
If work is to be carried out on public roads, obtain permission from LTA.
1.4.19
Security
Adequately safeguard the site, products, materials, plants and any existing buildings affected by the
Works from theft.
1.4.20
Pest Control
Engage a pest control operator who is registered with the BCA under the Work Head for Pest Control to
provide comprehensive pest control and surveillance work on the Site.
Submit the name of the pest control operator and proof of BCA registration to the SO for acceptance
prior to commencement of the Works.
Pest control and surveillance programmes shall comply with the requirements of the NEA as listed
below:
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(a)
Submit a detailed pest control and surveillance programme to the Environmental Health Office, NEA prior
to commencement of the Work.
(b)
Maintain a site register containing an up-to-date record of pest control and surveillance that have been
carried out. Make site register available for inspection by the SO.
(c)
Take all necessary measures to prevent the site (including vacant flats where relevant) from becoming
conducive to the breeding or harbouring of vectors.
(d)
Carry out site checks at least once a week to detect and remove breeding and harbouring grounds.
1.4.21
Pollution Control
1.4.21.1
General
Take all reasonable precautions to prevent pollution of the site and the general environment, including
streams and waterways. If pollution occurs, inform the appropriate authorities and the SO immediately
and provide them with all relevant information.
1.4.21.2
Air Pollution Control
Take all necessary measures to abate the discharge of smoke, fumes or obnoxious gases from any
construction equipment.
Stop using construction equipment discharging excessive smoke, fumes or obnoxious gases and
replace it with the accepted equipment.
Comply with the relevant provisions of the Environmental Pollution Control (Air Impurities) Regulations
and/or any requirement of other relevant authorities.
1.4.21.3
Dust Control
Take all necessary measures to control the dust such as periodically spraying demolition works with
water.
For buildings exceeding 6 storeys, erect fine netting adequately supported to a minimum height of 6 m
above the hoarding for further dust control.
1.4.22
Fire Prevention
Take all necessary precautions to prevent personal injury, death and damage to the Works or other
properties from fire. Comply with SCDF’s requirements for Fire Prevention on Construction Sites.
[Note 1: Existing buildings, particularly old ones and those that are listed will generally represent
an extreme risk where additional precautions are necessary.]
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1.4.23
As-Built Site Survey
Carry out a complete topographical survey of the Site upon completion of the Works indicating levels
of ground and remaining structures and services, and other ground features remaining on site.
1.4.24
Quality Control Plan
Submit and work to a quality control plan as agreed with the SO. Refer to the Section G01-010:
Clause:1.4.7.
1.5
Definitions and Abbreviations
1.5.1
Definitions
1.5.1.1
temporary works
All construction works that are not part of the permanent works but are required in order to complete the
permanent works.
1.5.2
Abbreviations
No item.
2
PERFORMANCE REQUIREMENTS
2.1
Contractor’s Design
2.1.1
Temporary Works
Design temporary works in accordance with the relevant standards and codes, and statutory
requirements. The design shall include foundations or other appropriate supports. Refer to BS EN
12811-1 that specifies performance requirements and methods of structural and general design for
access and working scaffolds.
2.1.2
Hoarding Design
Design hoarding in accordance with the relevant statutory requirements. Ensure
that the hoarding erected is able to resist all relevant design loading.
2.2
Falsework
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2.2.1
Foundations
Foundations for falsework shall be suitable to sustain the calculated maximum loads without failure or
unacceptable settlement.
2.2.2
Duration of Use
Falsework shall remain in place until the elements of the permanent construction are capable of selfsupport.
2.2.3
Protection from Impact
Protect falsework from accidental impact such as passing vehicles, plant and cranes. Where a
residual risk of impact is identified design the system accordingly.
[Note 1: Bollards and barriers, or concrete encasement may be used at low level. There may be a
risk due to crane swinging, etc., which needs to be considered. A horizontal load of 25 kN is
sometimes adopted for design but this needs to be assessed together with the level at which it would
be applied.]
2.3
Ground Movements and Vibrations
Generally comply with the requirements of BS 5228-1.
The vibration generated by the works in MRT structures not to exceed a peak particle velocity of 15
mm/s.
Unless otherwise directed, refer to Section C02-050: Clause:4.2.2 for general restrictions on ground
movements and vibration limits for adjacent structures where relevant.
2.4
Noise Nuisance
Take all necessary actions to ensure compliance with the Environment Public Health Act or the current
noise control regulations imposed by the NEA and any relevant authorities.
2.5
Works within Railway Protection Zone and Railway Safety Zone
Comply with all the provisions under the latest LTA Code of Practice for Railway Protection and the
Guide to Carrying Out Restricted Activities within Railway Protection and Safety Zones for the Works
and other activities within the railway protection zone and railway safety zone.
3
MATERIALS AND EQUIPMENT
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3.1
Falsework
Comply with the requirements of SS 580, BS EN 12812, and BS 5975 where appropriate.
[Note 1: SS 580 is code of practice for formwork (formerly CP 23).
Note 2: BS EN 12812 specifies performance requirements and sets out the rules that have to be
taken into account on falsework structure. BS 5975 gives guidance on the procedural controls to be
applied to all aspects of temporary works and includes guidance on design, specification,
construction, use and dismantling of falsework.]
3.2
Backfill Material
Comply with the requirements of Section C02-020: Clause:3.1, unless otherwise agreed by the SO.
3.3
Scaffolds and Access Equipment
Comply with the requirements of BS EN 12811-1 and BS 5974, and WSH Act and Regulations.
3.4
Prohibited Equipment
Do not use the prohibited equipment and methods as scheduled in the drawings or as directed by the
SO.
4
WORKMANSHIP
4.1
Survey
Prior to the commencement of the Works, verify all available information. Carry out a detailed visual
survey and examination of the physical condition and structural stability of the building(s) to be
demolished and other surrounding buildings.
Take photographs where necessary.
Carry out a further survey and examination of the structures on completion of the Works.
[Note 1: This clause requires a detailed post tender survey by the Contractor, an essential activity
if subsequent problems are to be controlled.
Information included in the tender documents or made available for inspection should be comprehensive
enough to enable the Contractor to comply with all parts of this clause.
Some types of structure present special hazards for demolition work, e.g., prestressed or post- tensioned
constructions. Demolition procedures described in Health and Safety Executive Guidance Notes GS29/3
should be followed.]
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4.2
Demolition Methods
Identify appropriate method for demolition by completing risk assessments for the Works. Adopt
specific precautionary safety measures appropriate to the proposed method.
Establish and maintain safe working spaces and exclusion zones as appropriate.
Ensure all personnel are familiar with and trained in the use of the particular plant and machinery
that will be used.
Follow the requirements of the method statement for the Works. [Note 1 :
Detailed guidance is given in BS 6187 and SS 557. ]
4.3
Precautions Against Uncontrolled Collapse
Ensure that the removal of certain parts of the building or structure during demolition will not affect the
structural integrity of other parts.
If at any time, it appears that the other parts have become unsafe or the structural integrity of the
building is compromised, propose all necessary remedial actions to provide adequate support to the
building to prevent uncontrolled collapse.
Pre-determine where temporary support will be needed. If the structure abuts other buildings, provide
such lateral support to prevent collapse.
Provide adequate shoring before the existing lateral support is disturbed.
4.4
Safety Measures
4.4.1
Sequence
Demolish buildings and other structures in the reverse order to that of their construction. The order of
demolition for buildings should be progressive storey-by-storey, having regard to the type of
construction.
4.4.2
Debris
4.4.2.1
Restrictions on Free Falling of Debris
Allow demolition debris to fall freely to the ground internally or externally only where the horizontal
distance from the point of fall to a public access or adjoining property is more than 6 m or half the
height from which the debris is dropped, whichever is greater. In any case, ensure the erection of
protective hoarding, safety netting/catch platform or other structures to protect public safety prior to
starting demolition works.
In cases when demolished material is allowed to fall freely externally, provide a covered hoarding
with catch fan. In other cases, use chutes or skips.
Prior to demolition of walls, sections of the floors should be removed by hand demolition to facilitate the
free fall of debris.
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4.4.2.2
Debris Accumulation
Do not allow debris to accumulate above an average height of 2 m from ground level. Prevent
debris from overloading scaffold platforms.
4.4.2.3
Use of Look-out
When material is being dropped, post a look-out man to ensure safety generally.
4.4.3
Use of Swinging Ball Method
Not used.
[This section is not used as the use of swinging ball method is no longer practised.]
4.4.4
Use of Explosives
Use of explosives will only be permitted subject to the following:
(a)
Obtain permission and approval from all relevant authorities.
(b)
Agree locations and times of use.
(c)
Comply with BS 5607.
(d)
Ensure that explosive charges are not excessive.
(e)
Protect properly charged boreholes.
(f)
Take proper precautions for the safety of persons and properties.
[Note 1: The use of explosives may not be permitted in densely populated areas. ]
4.4.5
Scaffolding Defects
Correct immediately any defects found during an inspection.
If this is not possible, do not use the scaffold that shall be out of use immediately by removing all
persons from it and placing a barrier and warning sign at each access point.
4.5
Temporary Structures
Keep all such structures away from proposed roads, driveways, car parks and services lines. Maintain all
such structures in a clean, hygienic and safe condition.
Remove all such structures on completion of the Works.
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4.6
Excavation
Refer to Section C02-020: Clause 4.2.
4.7
Adjoining Properties
When demolishing structure(s) against adjoining property, leave adequate temporary support and
protection at each stage.
Maintain and alter temporary supports and protection as necessary as work progresses.
Ensure the Works do no cause damage to adjoining properties and do not leave unnecessary or
unstable projections.
Do not disturb foundations of adjoining properties.
Report to the SO any defects exposed or becoming apparent in adjoining properties.
Promptly repair any damage caused to adjoining properties by the Works. Make good to ensure
safety, stability, weather protection and security.
4.8
Partly Demolished Structures
Cut away and strip out with care to reduce the amount of making good to a minimum. Prevent
debris from overloading any part of the structures to be retained.
Leave partly demolished structures in a stable condition with adequate temporary supports at each
stage to prevent risk of uncontrolled collapse.
Prevent access of unauthorised persons to partly demolished structure(s).
4.9
Works within Railway Protection Zone and Railway Safety Zone
4.9.1
Restrictions on Plant
No jib, lifting appliance or any other moving and stationery parts of the mechanical equipment shall
encroach within 6m on plan from the edge of the nearest Mass Rapid Transit above- ground structures
unless the equipment is restricted to work beneath the structure.
Engage a Professional Engineer to certify that the foundation of the mechanical equipment is structurally
sound and adequate prior to its installation.
Install an auto cut-off system for tower cranes to prevent the top of boom to swing closer than 6m from
edge of viaduct structure. The jibs of the cranes shall be pointed away from Mass Rapid Transit
structures. The temporary access shall be stable for machinery to move on.
4.9.2
Equipment Checks
Carry out regular checks to ensure that all mechanised equipment are in good working condition
at all times.
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4.9.3
Equipment Operators
Employ only experienced, trained and competent operators for mobile cranes, tower cranes and
other mechanical equipment.
4.9.4
Height Restriction
Install a temporary height restriction gantry with signboard 6m away from the edge of both sides
of the viaduct structure for any access passing underneath the Mass Rapid Transit structures.
4.10
Removal of Asbestos Material
4.10.1
Location of Asbestos
If known to exist, asbestos materials are identified at locations as shown in the drawings.
[Note 1: Where asbestos is present, the information should be provided in the drawings as
comprehensive as possible in terms of location, type and nature for examples tiles, insulation, etc.]
Undertake an independent survey to ascertain the presence, location, extent and nature of asbestos
materials in the buildings.
Report immediately to the SO any suspected asbestos materials discovered during demolition. Avoid
disturbing such materials.
Agree with the SO on safe methods for removal.
4.10.2
Regulations
Undertake all asbestos removal work in strict accordance to the "Guidelines on Handling Asbestos
Materials" and "Code of Practice for Handling of Asbestos Materials" issued by WSH Act, MOM.
In general, notify MOM, Chief Inspector of Factories prior to commencement of the work in accordance to
the Factories Act (Asbestos) Regulations, and Factories (Asbestos) (Amendment) Regulations.
Submit X-ray examination report of the workers prior to commencement of the work to the OHD,
MOM.
[Note 1: These guidelines spell out safe work procedures and practices that workers carrying out such
removal should follow.]
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4.10.3
Preparation of Area
Prior to the physical removal of the asbestos materials, carry out preparation of the asbestos work area
by removing all movable objects to prevent contamination. Cover all immovable objects with
polyethylene sheeting.
Demarcate the asbestos work area to prevent unauthorised access, including warning signs. Remove
the asbestos materials with minimal breakage and supplement by vacuuming using High Efficiency
Particulate Air (HEPA) filter and/or wet method using water spray.
4.10.4
Safety Precautions
Ensure all workers to use respirators, goggles and protective clothing.
Collect all debris, used respirators, goggles and protective clothing into sealed and labeled impermeable
containers. Consult NEA on the disposal of asbestos materials.
4.11
Precautions against Vibrations and Concussion
Take special care for demolition of tall buildings to ensure that no undue vibration or concussion is
caused which could result in damage to other properties, MRT structures, pedestrian crossings,
underground services or drains or other adjacent properties by flying debris.
4.12
Site Drainage
Prevent ponding on site from rainwater or other causes by pumping, creation of bunds, use of temporary
drainage or other means prior to backfilling/levelling.
4.13
Unknown Hazards
Inform the SO of any unrecorded tanks, chemicals, etc., discovered during demolition work. Agree with
the SO methods for safe removal, filling, etc.
4.14
Open Basements
Leave adequate buttress walls or provide temporary support to basement retaining walls up to ground
level.
Make the remaining sections of any retaining and buttress walls safe and secure.
Make holes in basement floors to allow water drainage or penetration (depending on water table).
Provide a hole not less than 600 mm in diameter for every 10 m² or as agreed with the SO.
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4.15
Filling of Basements
Leave adequate buttress walls or provide temporary support to basement retaining walls up to ground
level.
Make holes in basement floors to allow water drainage or penetration (depending on water table).
Provide a hole not less than 600 mm in diameter for every 10m² or as agreed with the SO.
Remove all organic material and soil from basements and other voids. Fill and consolidate with material
as indicated in the drawings.
[Note 1: Specify any particular requirements for fill material and drainage provision. The former might be
e.g., well-compacted hardcore/selected material placed in layers not exceeding 150 mm thickness or
foamed concrete.]
[Note 2: Use this clause when it is advantageous for filling to be carried out as a demolition item.
Basement party walls should be inspected to ensure they could withstand the pressure exerted by the
fill. Where basements extend beneath footpaths or roads, they should be filled to the satisfaction of
Land Transport Authority.]
4.16
Reinstatement and Making Good to Disturbed Areas
4.16.1
Services
Temporarily disconnect and/or divert all affected services prior to the commencement of Works and
reinstate immediately upon Substantial Completion of the Works.
Reinstate and make good the affected Works and services in such a manner that upon
substantial completion, they shall be in as good order and condition as they were at the
commencement of the Contract.
4.16.2
Backfilling / Leveling / Compaction
Refer to Section C02-020: Clause:4.7.
4.17
Completion
Clean all rubbish, debris and surplus materials and leave the whole site clean and tidy. Complete to
the required final condition of the Site as indicated in the drawings or as directed by the SO.
[Note 1: Example on requirements:
- Grade the site to follow the levels of adjacent areas
- Cover the site using ... mm thick consolidated layer of ashes and ... mm thick consolidated layer of crushed hard
rock.]
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4.18
Preparation for Cultivation with Turfing
Clean all loose stones, gravels, tree stumps and building debris in the areas indicated for turfing
on the drawings.
Loosen the top 100 mm deep layer and grade to fall as indicated.
For specific requirements on turfing, refer to architectural specifications.
4.19
Other Particular Requirements
Comply with other project specific requirements or restrictions for the Works as indicate in the drawings or
directed by the SO.
[Note 1: State any particular restriction on the methods or working conditions etc. if applicable to the
project. ]
5
VERIFICATION AND SUBMISSION
5.1
Work Submissions
Propose for the SOs acceptance, the list and timing for required submissions for the Works as follows
where applicable :
5.1.1
(a)
Design Submission
(b)
Method Statements
(c)
Site Management
(d)
Site Layout Plan
(e)
Survey Report
(f)
Scaffolding/falsework Inspection
(g)
Proposals for Monitoring MRT Structures for Vibration
(h)
Works within Railway Protection Zone and Railway Safety Zone
Design Submission
Submit the design, calculation and detailed drawings of temporary works, temporary hoarding,
scaffolding and staging to the SO for acceptance at least 14 days before commencement of the
relevant work.
[Note 1: Buildings which may be adversely affected by demolition works include those housing sensitive
equipment, (e.g., laboratories, hospitals, schools, etc.)
Insert details of other information reasonably required to allow development of the appropriate health and
safety procedures, e.g.,
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5.1.2
(a)
results of tests to determine the precise nature of hazardous materials.
(b)
details of services supplied by the statutory boards.
(c)
structural calculations in support of method statements procedures and arrangements generally applicable
to the demolition.]
Method Statements
Submit method statements covering the following and describing how and when the following tasks are
carried out within 14 days from commencement of the relevant work:
(a)
Sequence, method and schedule of demolition
(b)
Sequence, method and schedule of excavation/backfilling
(c)
Services detection
(d)
Existing site surveys
(e)
Temporary access roads
(f)
Temporary access stairways and walkways
(g)
Temporary works
(h)
Temporary supports of buildings/services to be retained
(i)
Temporary hoardings
(j)
Scaffolding and staging
(k)
Fans and any other temporary works required
(l)
Plant and equipment
(m)
Debris disposal
(n)
Rubbish disposal
(o)
Asbestos material removal
(p)
Reinstatement and making good
(q)
Noise nuisance control
(r)
Vibration control
(s)
Pest control
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(t)
Pollution control
(u)
Dust control
(v)
Fire prevention
(w)
Safety measures
[Note 1: Add any other additional items in the submission here.
Potential risks to health and safety arising from the nature and condition of the site/existing buildings(s)
shall be identified in the Specification.
To specify maximum noise levels and the hours during which work may be carried out.
Vibration may also be restricted if surrounding buildings are old or of historical importance, or are
particularly sensitive to vibration.]
5.1.3
Site Management
Submit to the SO for acceptance the following details soon as practical from commencement of the
Contract:
(a)
Site organisation structure
(b)
Names and qualifications of Contractor’s staff
(c)
Names and qualifications of site safety supervisors
(d)
Names and qualifications of pest control operators
(e)
Names and qualifications of scaffolding inspectors
(f)
Quality control plan
(g)
Additional requirement as noted in the PSD
[Note 1: Add any other additional items in the submission here. ]
5.1.4
Site Layout Plan
Submit a site layout plan to the SO indicating proposed locations of all temporary structures for
acceptance before their erection.
Notwithstanding such acceptance, relocate any such structures when required to do so by the SO.
5.1.5
Survey Report
Submit a survey report to the SO covering at least the following information:
(a)
Form, condition and demolition methods of the structure(s)
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(b)
Form, location and removal methods of any toxic or hazardous materials
(c)
Type and location of adjoining properties which may be adversely affected by noise, vibration, dust or
removal of structure
(d)
Identification and location of services above and below ground
(e)
Type and location of any features of historical, archaeological or geological importance
(f)
Any potentially dangerous site conditions
(g)
Any constituent materials have deteriorated in strength to an extent that could result in instability due to a
particular demolition process
Scaffolding/ Falsework Inspection
Submit scaffolding inspection record to the SO, including date of inspection, name of inspector and any
defects/modifications/rectifications carried out.
5.1.7
Proposals for Monitoring MRT Structures for Vibration
Submit proposals for monitoring the MRT structures for vibrations generated by the demolition works to
the LTA for approval prior to the commencement of the Works, including the following:
5.1.8
(a)
Proposal for monitoring the MRT structures for vibration generated by demolition work.
(a)
Method statement of demolition, including sequence, equipment to be used and proposals to reduce
impact from falling debris onto the ground.
(b)
Proposal to trap/minimise dust from being sucked into MRT vent shaft and affecting the railway operation.
(c)
Condition survey of the affected structure carried out by an independent qualified building surveyor.
Works within Railway Protection Zone and Railway Safety Zone
Submit proposals on effective measures for the protection of MRT above ground structure together
with the detail of activities of mobile cranes, tower cranes and other mechanical equipment adjacent
to MRT structures to the SO for acceptance at least 1 month prior to the use of such equipment.
5.1.9
Quality Control Plan
Prepare and submit the quality control plan for SOs acceptance prior to starting work.
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5.2
As-built Survey
After the completion of the demolition works, engage a Registered Surveyor to carry out a site survey of
the Site and immediate surround.
Submit copies of the survey plan as directed by the SO showing at least the following information:
(a)
Level of ground and structures
(b)
Existing structures known, both above and below ground
(c)
Existing services
(d)
Demarcation of property boundaries
(e)
Reserved zones as required by the authorities
(f)
Street furniture, drainage systems, etc.
(g)
Existing trees in accordance to NPark requirements
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1
GENERAL
Read this Section with Section G01-010 "General Requirements" and all other contract documents.
1.1
Scope
This Section covers the requirements for the condition survey of buildings, services and other structures
within the area of influence of other construction works. This includes condition survey that is carried out
prior to and or after the execution of the construction works.
This Section applies generally to buildings, services and other structures that could be affected by
works such as the following:
(a)
Demolition
(b)
Piling
(c)
Earthworks
The requirements for instrumentation for monitoring are given in Section C02-050 "Instrumentation and
Monitoring".
[Note 1: Use the drawings to set out the specific requirements in terms of requirements or performance for
a given project.
The Work covers two specific aspects: the initial survey, followed by the monitoring during the course of the
Work. In some cases, a post-condition survey is required.
The survey is only for the purpose described, and makes no representation concerning the underlying
condition or integrity of the buildings/structures/services concerned, although the responsibility of the
Contractor to avoid damage to the buildings remains as stated in the related section.]
1.1.1
Prescribed Scope of Survey
Carry out the condition survey for the specific buildings as identified and shown in the drawings or as
directed by the SO.
[Note 1: Specifier may define specific buildings here, such as conserved buildings, essential buildings,
etc.]
1.2
Related Sections
Read this Section in conjunction with the relevant requirements of the following section:
C02-050
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1.3
Standards, Codes, Regulations and Technical References
Undertake the Works in compliance with all standards and regulations as required by the authorities.
1.4
Trade Preamble
1.4.1
Contractor’s Submissions and Proposals
Propose suitable methods of survey and instrumentation for the purpose of monitoring, for SOs
acceptance and comply with such.
1.4.2
Access to Adjacent Sites
Obtain appropriate permission for access to adjacent sites prior to commencement of the Works. Provide
arrangements for the access as shown in the drawings or as directed by the SO.
1.4.3
Quality Control Plan
Submit and work to a quality control plan as agreed with the SO. Refer to the Section G01010:Clause:1.4.7.
1.4.4
Verification of information
Obtain relevant information on existing buildings, services and other structures from the SO. Verify the
information given and, if necessary, carry out additional investigation or request from the Authorities to
ensure that adequate information is available to carry out the works
1.4.5
Notice of Survey
Provide within time specified in the drawings, notice of the intended date and scope of condition and postcondition surveys to the affected parties.
1.4.6
Instrumentation and Monitoring
Install suitable instrumentation for continuous monitoring of the conditions of the prescribed buildings in the
course of other construction works. Based on the condition of the buildings surveyed, propose suitable
schedule of instrumentation and frequency of readings for the SOs acceptance.
Take cognisance of and co-ordinate with other contractors on site who may be carrying out instrumentation
and monitoring works to avoid duplication of installation and readings.
For general requirements of the instrumentation, refer to Section C02-050 "Instrumentation and
Monitoring".
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1.4.6.1
Instrumentation Engineer
Engage a suitably qualified and experienced engineer for the instrumentation and monitoring work to
the SOs acceptance, to install, record readings and report for all instruments and monitoring.
S1.5
Definitions
a.
Trigger Value
The value of movement or vibration detected as reaching the
“Alert” or “Work Suspension” level as defined below.
b.
Alert Level
The value of movement or vibration detected at which the
frequency of readings is reviewed and the instrumentation
checked.
c.
Work Suspension Level
The value of movements or vibration detected at which the
work causing the movement or vibration is halted pending
further review of both the structure and the methods of
working.
2
PERFORMANCE REQUIREMENTS
2.1
The Survey
Provide adequate information to allow agreement as to the condition of the identified buildings, services
or other structures prior to the commencement of the construction works and any change in that
condition that has occurred during and upon completion of the construction works.
2.2
Instrumentation and Monitoring
Provide adequate record to identify changes that have occurred and allow changes to methods of the
construction works in order to avoid or minimise damage to the surveyed buildings.
When planning for suitable methods and instrumentation for the survey, take account of the limits
on movements and levels of vibration, Section C02-050:Clause:4.2.2, as well as in the respective
work sections relevant to the other construction works. Also take account of the frequency of
monitoring as indicated in the respective sections.
3
MATERIALS AND EQUIPMENT
3.1
Instrumentation
For general requirements of instrumentation and monitoring works, refer to Section C02-050
"Instrumentation and Monitoring".
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3.2
Camera
Use a camera capable of producing digital records of the survey unless otherwise agreed with the SO.
[Note 1: Add detailed specification on the clarity of digital images required. Refer also to Section C01020:Clause:4.2.]
4
WORKMANSHIP
4.1
Working Method
Plan to carry out the Works in a manner that the Works do not cause any damage to the buildings,
services or other structures. Submit a workable and reliable working method to the SO for acceptance.
If damage is inevitable, provide a solution to rectify the damage to the SO for acceptance prior to
commencement of any work.
4.2
Photographic Record
Unless otherwise agreed by the SO, submit digital colour photographs to the SO for record.
Where a digital camera is used, submit an electronic copy of the photographs in a *.jpg or *.bmp format or
any other format as agreed by the SO.
The photographs shall show clearly all required details and shall contain a graduated scale and colour
chart for reference. These photographs shall be taken under natural light condition and the intensity of
light shall be uniform to reflect the natural colour of the intended objects. Use flashlight only as agreed.
Ensure that all labels and markers are clearly identified within the photograph.
4.3
Installation of Instrumentation
Give at least 48 hours’ notice of the intention to install any instrument unless otherwise agreed by the
SO. Install all instruments and establish initial readings prior to the construction activity or area of works
to which they relate unless otherwise agreed by the SO.
4.4
Crack Survey
Carry out a visual survey of all structural elements in the adjacent properties for cracks in excess of 0.1
mm. Notify the SO if there are signs of structural damages. Mark the location of cracks thus identified
on plans and elevations as appropriate.
The survey shall include at least the cracks previously identified in the crack schedule as shown or
indicated in the drawings or as directed by the SO.
[Note 1: Drawings should provide and describe as actual width/hairline/taper dims; add any comment, e.g.
plaster/paint flaking around crack, crack follows mortar joint/brick fractured, horizontal displacement
across crack, etc.]
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4.5
Level Survey
Establish the initial (datum) reading of each survey point and submit records to the SO. Protect the
datum during monitoring period.
4.6
Reflector Targets
Install prism reflector targets at the locations shown in the drawings.
4.7
Plumb Survey
Carry out a plumb survey to establish the verticality of the members where necessary.
4.8
Record of Defects
Record any obvious defects on plans/elevations.
4.9
Reading of Crackmeters and Tiltmeters
Typical details of acceptable installations for ground and building settlement points are shown in the
drawings.
Submit for approval details of any alternative installations.
Monitor and record the levels of ground survey and building settlement points throughout the duration of
the Works to the accuracy of 0.5 mm.
4.10
Readings of Vibration Sensors
Readings to be carried out by qualified personnel only.
4.11
Monitoring Records
Review the monitoring records on receipt. Notify the SO immediately if the alert or work suspension
levels are reached and agree on any action proposed.
4.12
Reinstatement
Reinstate all affected or damaged areas to the acceptance of the SO.
5
VERIFICATION AND SUBMISSION
5.1
Submissions
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5.1.1
Method Statement
Submit to the SO for acceptance, a method statement containing the following information for the
buildings, services or other structures to be surveyed and monitored:
5.1.2
(a)
Nature of survey to be undertaken
(b)
Scheduling and timing of survey and monitoring
(c)
Differentiating between initial survey and subsequent monitoring
(d)
Effect of alert and work suspension levels on timing of subsequent monitoring
(e)
Personnel undertaking survey and monitoring
(f)
Special concern and method of survey and monitoring
(g)
Anticipated damage to the surveyed area and proposed method of reinstatement
Proposals for Monitoring
Provide proposals for monitoring in the form of a method statement to the SO prior to
commencement of the Work or as soon as practicable during the survey if the results indicate the need
for additional monitoring.
The proposals shall include the following:
5.1.3
(a)
Proposed instrumentation
(b)
Details and drawings of instruments
(c)
Manufacturer’s specifications and recommendations for installation and maintenance
(d)
Details of sequence of assembly and connections
(e)
Location of instrumentation
(f)
Programme of installation
(g)
Details of monitoring arrangements and verification procedures
(h)
Frequency of readings
(i)
Format of records
Quality Control Plan
Prepare and submit the quality control plan for SOs acceptance prior to starting work. Refer to
Section G01-010:Clause:1.4.7.
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5.2
Survey Records
Submit survey records within the time frame as as agreed by the SO after completion of the survey.
Provide each neighbouring owner a copy of relevant portion of the survey as directed by the SO.
Survey records shall include:
(a)
Photographic Records (Section C01-020:Clause:4.2)
(b)
Crack Survey Records (Section C01-020:Clause:4.4)
(c)
Level Survey Records (Section C01-020:Clause:4.5)
(d)
Records of Defects (Section C01-020:Clause:4.8)
(e)
Plumb Survey Records (Section C01-020:Clause:4.7)
5.3
Monitoring Records
5.3.1
General
Submit 2 copies of preliminary records of the installation of each instrument within 24 hrs from the time
of installation of each instrument.
Submit final records for each instrument incorporating any comments from the SO within 7 days of
completion of installation of each instrument.
5.3.2
Record information
The records shall incorporate a graphical illustration of the instrument installation and shall include the
following information:
(a)
Instrument number and location (in eastern and northern co-ordinates and level)
(b)
Names of personnel responsible for installation
(c)
Time and date for commencement and completion of instrument
(d)
Plant and labour used
(e)
Ground conditions encountered (if applicable)
(f)
Details of instrument installation (grout, fixings, etc.)
(g)
Instrument readings during installation, calibration and immediately after installation are completed
(h)
Location of instrument terminals, housings and any leads or cabling
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5.3.3
(i)
Details of any splices, numbers of casings or joins
(j)
Details of any breakdowns or delays
Factual Reporting
Submit the factual reports of monitoring results at intervals as specified or indicated in the drawings or as
agreed by the SO.
Submit to the SO in a format acceptable to the SO, a plan showing the location of the structure and
instrumented lines and comprise at least the following:
(a)
Plots of measured parameters vs time, depth and/or location of construction activity with reference to each
instrument etc., as agreed with the SO.
(b)
A comparison of data with predetermined trigger values (alert or work suspension levels),
e.g. settlement vs time, horizontal deflections vs time, load vs depth of excavation, settlement vs
location of construction activity / depth of excavation, etc.
(c)
Highlight of idle or damaged instrument and provide estimated time frame for corrective measures.
5.3.4
Interpretative Reporting
5.3.4.1
Frequency
Based on the factual information received, submit for the SOs acceptance interpretative reports of
monitoring results at intervals as agreed by the SO.
When established trends indicate potential problems then such areas of concern shall be re- appraised at
intervals consistent with the data collection and reports issued accordingly as required.
5.3.4.2
Report Content
Interpretative Reports shall include a summary plot of all instrumented lines or points which indicate a
trend (including historical data where appropriate) that could result in a work suspension level being
exceeded and any instrumented line or point in which a work suspension level has been exceeded.
Submit recommendations for any protective measures or actions that are necessary.
5.4
Post-completion Survey Records
Submit the post-completion survey for the SO for record. Follow the same procedures as for the precondition survey unless otherwise required by the SO.
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1
GENERAL
Read this Section with G01-010 "General Requirements" and all other contract documents.
1.1
Scope
This Section covers the requirements for ground investigation, including:
(a) Boring and drilling
(b) Excavation of trial pits and trenching
(c) Probing
(d) Sampling
(e) In-situ testing and laboratory testing
(f) Monitoring
This Section does not cover geophysical methods of investigation
1.2
Related Sections
Read this Section in conjunction with the relevant requirements of the following sections:
1.3
C02-020
General Earthworks (Excavation and Filling)
C02-050
Instrumentation and Monitoring
Standards, Codes, Regulations and Technical References
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1.3.1
Standards and Codes
Unless otherwise agreed by the SO, ensure all of the Works comply with the relevant requirements
of the standards and codes listed below or referenced in the body of the Specification. Alternative
standards and codes may be proposed for approval by the SO, provided it can be demonstrated that
the alternative standards and codes comply with the requirements of the standards specified. All
standards and codes quoted are the current version, unless specific year references are noted.
In the event that the standards or codes are partially superseded or have become obsolete, refer to
the current edition or the approved substitution for the relevant clauses.
Singapore Standards
SS EN 1997-1
Eurocode 7: Geotechnical design - Part 1: General rules
SS EN 1997-2
Eurocode 7: Geotechnical design - Part 2: Ground investigation and
testing
SS CP 79
Safety management system for construction worksites
Other Standards
BS EN ISO 14688-1
Geotechnical investigation and testing - Identification and classification of
soil - Part 1: Identification and description
BS EN ISO 14688-2
Geotechnical investigation and testing - Identification and classification of
soil - Part 2: Principles for a classification
BS EN ISO 14689- 1
Geotechnical investigation and testing. Identification, description and
classification of rock. Part 1: Identification and description
BS EN ISO 17892
Geotechnical investigation and testing. Laboratory testing of soil
BS EN ISO 22475-1
Geotechnical investigation and testing. Sampling methods and
groundwater measurements. Technical principles for execution
BS EN ISO 22476-1 to 15
Geotechnical investigation and testing - Field Testing - Parts 1 to 15
BS EN ISO 22282-1 to 12
Geotechnical investigation and testing - Geohydraulic testing - Parts 1 to
12
BS 5930
Code of practice for site investigations
BS1377-1 to 9
Soils for Civil Engineering Purposes - Parts 1 to 9
ASTM D1785
Unplasticized PVC pipe for industrial purposes
Unless Singapore Standards are not available, all Eurocodes shall mean and refer to the Singapore
Standard EN and their National Annexes.
1.3.2
Technical References
Refer to the following technical references for guidance in carrying out the Works:
(a)
International Society of Rock Mechanics (ISRM), Standardisation of laboratory and field tests. Suggested
Methods for determining the uniaxial compressive strength and deformability of rock materials
(b)
International Society of Rock Mechanics (ISRM), Testing methods. Suggested Method for determining point
load strength
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(c)
BRE Special Digest 1 Concrete in aggressive ground
(d)
BRE Digest 251 Assessment of damage in low rise building
(e)
BCA/IES/ACES, Advisory Note 1/03 on Site Investigation and Testing
(f)
Geological Map of Singapore
(g)
BCA, Guidelines for Electronic Transfer of Site Investigation Data
1.4
Trade Preamble
1.4.1
Contractor’s Submissions and Proposals
Propose for the SOs acceptance Provisional Bill of Quantities as provided in Appendix 1 to Section
C020-010 "Ground Investigation" on the Works to be carried out as part of the ground investigation.
1.4.2
Co-ordination with Other Works
Co-ordinate with other contractors who may carry out other works at the same time at the Site. Take into
account site access, space occupation, safety and safeguarding of adjoining properties and each
other’s works.
1.4.3
Temporary Access
Provide temporary accesses required for the execution of the Works. Provide at all times during the
progress of the Works proper means of access and the necessary attendance for inspection of the
Works by the Employer or the Employer’s Representative as directed.
1.4.4
Water Supply
Provide water required in connection with the Works, including the supply and fixing of all fittings,
maintenance of the supply, removal of all fittings and making good all disturbances after completion of
the Works.
1.4.5
Electrical Power Supply
Make all necessary arrangements and supply any electrical power required for the Works.
1.4.6
Storage Facilities
Provide proper facilities for the storage and protection of soil, rock and water samples. These facilities
shall provide protection at all times from temperatures in excess of 35°C and from wetting or drying out
due to weather exposure.
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1.4.7
Quality Control Plan
Submit and work to a quality control plan as agreed with the SO. Refer to the Section G01010:Clause:1.4.7.
1.4.8
Personnel
1.4.8.1
Supervising Site Personnel
Engage qualified, competent and suitably experienced site personnel with the SOs acceptance, to
supervise the Works and verify the accuracy of the investigation findings. Information on items to be
verified, checked or monitored during the Works shall be clearly identified and made known to the
supervising personnel.
1.4.8.2
Endorsing Professional Engineer
Engage a suitably qualified, experienced and competent Professional Engineer (PE) to verify the
accuracy of the investigation findings, tests and results, including all field and laboratory works, and
interpretative reports as appropriate, and to endorse the ground investigation report.
1.4.8.3
Registered Surveyor
Employ a Registered Surveyor to survey investigation points, including borehole locations and levels, and
specific investigative locations, and submit the results to the SO together with the ground investigation
report.
1.4.8.4
Engineering Geologist
Engage a suitably experienced, qualified and competent engineering geologist at the Site to ensure the
use of proper equipment, methods and procedures, materials and quality of the Works in compliance
with specifications, and to ensure correct and accurate logging, sampling and testing in accordance with
specified standards and codes.
1.4.8.5
Driller
Engage a competent, qualified, and experienced driller who is in charge of drilling operations and the
rig to ensure the use of proper equipment, methods and procedures, and materials for boring, drilling,
probing, sampling, field tests, making groundwater observations in boreholes and properly recording the
information obtained in accordance with the specifications and standards.
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1.4.9
Upholding of Adjoining Properties
Accept responsibility for the upholding of the adjoining buildings and roads, footpaths etc., where
applicable, together with the mains and services from the time of taking possession of the Site
through the duration of the Works.
Adequately maintain roads and footpaths within and adjacent to the Site and keep clear of mud and
debris.
1.4.10
Removal of Personnel, Improper Plant, Equipment or Tool
Remove from the Site and replace any plant, equipment or tool not conforming to the requirements of the
Specification and standards.
Remove from the Site any personnel or operative found incapable or unsuitable for the Works, or refusing
to follow or comply with the work procedure as specified, and replace without delay such personnel as
directed by the SO.
1.4.11
Existing Services Affected by the Works
Ensure that existing services affected by the Works are detected, protected and/or diverted. Comply with
all requirements by the Authorities.
1.4.12
Damage to Overhead and Underground Mains and Services
Take due care to avoid damages to electricity mains, water mains, telephone lines, sewerage mains,
gas mains and the like.
Ascertain the positions of all utility mains or services in the vicinity of the exploratory hole. Inform the
SO immediately and propose alternative location for the SOs acceptance if any of the location of the
exploratory hole coincides with the position of the utility mains or services.
[Note 1: Trenching works can potentially damage underground utilities and services.]
1.4.13
Laboratory Testing Facilities
Propose for SOs acceptance to carry out the laboratory testing at accredited testing laboratory or
at an independent laboratory as directed by the SO.
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1.4.14
Photographs
Supply digital colour photographic records and data taken with proper lighting of samples, rock cores,
excavation face of trench, trial pits, site conditions or such portion of the Works in progress or as
directed by the SO, within 7 days of the taking of the photographs.
Propose to the SO for acceptance with regard to the quality and format of digital images. Photographs
shall show clearly all required details and shall contain a graduated scale and colour chart in a format
to be agreed by the SO.
Take the photographs under natural light condition with uniform intensity of light to reflect the natural
colour of the intended object, e.g. cores, trenches, etc.
[Note 1: As a minimum, digital images shall be at least 12 megapixels ( MP) and the camera sensor
size not less than Advanced Photo System type-C (APS-C).]
1.4.15
Instrumentation and Monitoring
Provide and monitor the instruments as indicated in the drawings or provided in the bill of quantities
or as directed by the SO to monitor vibrations, noise and ground movements. If necessary or as
required by the Authorities, propose and provide additional instrumentation and monitoring for
records.
Take cognisance of and co-ordinate with other contractors on site who may be carrying out
instrumentation and monitoring works to avoid duplication of installation and readings.
For general requirements of the instrumentation and monitoring works, refer to Section C02- 050
"Instrumentation and Monitoring".
1.4.16
Fenced Protection
Protect all equipment and working area using fencing or other methods as appropriate.
1.4.17
Noise and Disturbance
Take all necessary actions to ensure compliance with the Environment Public Health Act and Regulations
or the current noise control regulations imposed by the NEA or any relevant authorities.
The noise level at the nearest occupied building outside the Site shall not exceed the maximum
permissible noise level stated in the NEA guidelines.
1.5
Definitions and Abbreviations
1.5.1
Definitions
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1.5.1.1
Accredited Testing Laboratory
This refers to an organisation or laboratory accredited under the Singapore Laboratory Accreditation
Scheme (SINGLAS), and fully equipped and accredited to carry out the relevant tests and checks
required by the Specification.
1.5.2
Abbreviations
No item.
2
PERFORMANCE REQUIREMENTS
2.1
General
Undertake the ground investigation works such that the execution, including boring, drilling, sampling,
logging, making groundwater observations, and field and laboratory testing, is carried out according to
the relevant standards and codes, with adequate supervision and quality control; and data are
collected, recorded and interpreted by appropriately qualified personnel.
Ground investigation comprising field investigations and laboratory testing, including drilling, sampling
of soils and rocks, and groundwater measurements, shall be carried out and reported in accordance
with internationally recognised standards and recommendations, in particular complying to the
principles and requirements of SS EN 1990 and SS EN 1997-1 and SS EN 1997-2 and the related
test standards cited therein. Deviations from these standards and additional test requirements shall
be subject to the SOs agreement.
2.2
Sampling of Soils and Rocks
Sampling of soils and rocks by drilling and excavations, and groundwater measurements shall be
conducted appropriately to provide the prescribed laboratory quality class in accordance with SS EN
1997 for testing and the basis for assessment and evaluation of geotechnical parameters under SS
EN 1997 requirements.
2.3
Description of Soils and Rocks
Provide and report detailed descriptions for engineering purposes of all the soil and rock samples
obtained. These engineering descriptions shall be accurately incorporated in the field logs to form part
of the ground investigation report.
For rotary cored boreholes, cores shall be logged and described in their fresh condition as the work
proceeds.
Where trial pits and other exploratory excavations are required and where existing natural or manmade exposures of the ground are involved, provide and report the detailed recording of the soils and
rocks, their stratification, structure and fabric.
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2.4
Method of Advancement and Locating of Boreholes
The method of advancement shall be such that the boring can be completed and logged to the specified
depth, with samples obtained, in-situ testing carried out and instrumentation installed as specified.
Borehole locations shall be surveyed prior to drilling commencement and the drilled position shall be
expressed in Northern and Eastern co-ordinate system with reference to the Singapore National
Grid.
All elevations, including ground level and top of instruments shall be in the nearest 50 mm relative to
the Singapore Height Datum (SHD).
2.5
Reporting Requirements
Reporting shall be in accordance with SS EN 1997 and all relevant authority requirements.
2.5.1
Digital Data
Digital data, including AGS format data, for the survey information, boreholes and test results is
required. The specific content and format shall be in accordance with BCA publication on guidelines
for electronic transfer of site investigation data, and shall be subject to the SOs approval.
3
MATERIALS AND EQUIPMENT
3.1
General
The drilling and sampling equipment shall be appropriate and in accordance with the following:
(a) Sampling categories and laboratory quality class as defined in SS EN 1997-2.
(b) Depth to be reached.
(c) Required diameter of the sample.
(d) Such functions required from the drilling rig as recording of the drilling parameters, automatic or manual adjustment.
3.2
Drilling and Sampling Equipment
Drilling and sampling equipment adequate to the soil sampling category prescribed in SS EN 1997-2
are required to be in accordance with EN ISO 22475-1.
Samples for tests as appropriate shall be in accordance with the sampling categories and laboratory
quality classes prescribed in SS EN 1997-2.
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3.3
Drilling Fluid for Rotary Coring
Use clean water, air or air mist. Drilling muds or additives may be used subject to agreement with the
SO. For ground conditions with artesian pressure, propose the unit weight of drilling fluid for the SOs
acceptance.
3.4
Casing and Support of Borehole Sides
Casing shall be used to the full depth of the boreholes at all times unless otherwise permitted by the
SO. Submit for the SOs acceptance other methods of stabilisation of the borehole.
Casing shall be used when there is doubt as to the effectiveness of the method of stabilisation. Methods
of stabilisation involving the use of bentonite or other drilling fluids shall not be used when permeability
tests are to be carried out or piezometers are to be installed.
3.5
Cement/Bentonite Grout for Backfilling
Mix equal portions by weight of ordinary Portland cement and bentonite by hand or machine to a
uniform colour and consistency before placing. Moisture content shall not exceed 250%.
The mix shall provide a proper seal against the borehole wall and prevent the formation of potential
seepage paths for groundwater through the borehole.
For backfilling boreholes where there is no groundwater, add just sufficient amount of water to produce a
pumpable mix.
Where there is water in the exploratory hole, add only sufficient water to form a cohesive paste.
3.6
Sample Tubes
Use hydraulic piston type of sampler unless otherwise agreed by the SO. Do not use plastic lining
tubes in substitution for steel or aluminium sampling tubes. Use Mazier Sampler in place of the thinwalled sampler for stiff soil with the agreement of the SO. Thin-walled sampler tubes shall be made of
steel or aluminium. Open tube and piston samples shall have a minimum of 75 mm internal
diameter.
3.7
Standpipes
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3.7.1
Tube
Standpipe shall consist of a minimum 25 mm internal diameter unplasticised polyvinylchoride (uPVC)
tube with minimum thickness of 2 mm with an end cap and slotted or perforated over its lower end.
Unless otherwise agreed by the SO, the slots or perforations shall be at least 1.5 mm wide, and evenly
distributed over the slotted or perforated part of the tube to provide a minimum open area of 30% of
the total circumferential surface. The slotted part of the tube shall be wrapped with filter fabric as
approved by the SO. The length of the slotted portion shall be 3 m at minimum.
The standpipe shall be placed in the borehole, backfilled with graded filter sand (600 to 2 000
micron) up to 1.0 m below ground level or as specified or as directed by the SO. The top 0.5 m (as a
minimum) of the borehole shall be sealed with a concrete plug and subsequent 0.5 m (as a minimum)
depth sealed with bentonite pellets or with an approved bentonite cement grout.
The top of the standpipe shall be covered by a plastic cap or similar as approved by the SO.
3.7.2
Filter
Where gravel filter is required, use pea gravel or similar material, 6 to 10 mm in diameter.
Where sand filter is required, the sand filter surround to the porous element shall be clean and fall
wholly between the limits of grading 1200 and 210 microns and the volume of the sand filter placed shall
be recorded. Ensure that no sand adheres to the soil in the sides of the unlined borehole. Where there
is water in the borehole, allow sufficient time for all the sand to settle.
The final elevation of the top of this sand shall be recorded. The porous element shall be placed in
the hole and the remaining sand filter shall then be added as described above.
3.7.3
Grouting
A grout of cement and bentonite shall be used. If water in the exploratory hole is contaminated by
grout, replace with clean water using a method or procedure to be agreed by the SO. Unless
otherwise approved by the SO, the grout shall consist of 4 parts of bentonite mixed with 10 parts of
water to which is then added 1 part of ordinary Portland cement.
[Note 1: It is common practice to seal the filter section with 0.5 m of bentonite pellets and then grout
above to protect the filter.]
3.8
Piezometers
The piezometer tip shall consist of a porous ceramic element or other elements not less than 150 mm
long with a diameter not less than 40 mm, and shall be protected at each end by UPVC fittings. The
porous element shall be a pore diameter of the order of 60 microns and permeability of the order of 3
x 10-4m/s. The tubes shall be jointed together and to the porous element with approved couplings and
glue in such a manner that the joints remain leak-proof under the anticipated head of water.
Piezometers shall generally be the Casagrande type or vibrating-wire type piezometers subject to the
SOs approval.
Refer to Section C02-050:Clause:3.10 for general requirements.
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3.9
Field Vane Shear Tests
The maximum period between calibration and use on site shall be 4 months. Submit calibration
certificates for acceptance by the SO before commencement of field test. Calibration shall be
repeated after completion of the site works.
Permitted tolerances on vane dimensions shall be ±0.5 mm due to either manufacture or wear.
Actual vane dimensions shall be measured at the start of Works to an accuracy of ±0.1mm.
The vane dimensions shall be checked at the end of the Works.
Permitted tolerances on the torque head measurements shall be ±5% of the measured value.
3.10
Pressuremeter Tests
The pressuremeter shall be properly and appropriately calibrated at frequent intervals, including
recalibrating daily or after every 10 tests or as directed by the SO for validation checks and
results obtained.
3.10.1
Volume or Radius Measurements
Methods of calibrating the volume or radius measurement system are required to include inflating the
pressuremeter in close fitting (10% expansion) and loose fitting (80% expansion) steel cylinders, and
calibrating individual feeler arms against a suitable micrometer or calliper gauge. Repeatable results to
within the required accuracy have to be obtained.
3.10.2
Pressure Measurements
An independent Bourdon gauge or equivalent device is required on site to check the calibration of the
pressuremeter and the inflation of the pressuremeter in air at the operating testing rate. The
repeatability of these tests shall be established.
3.10.3
Equipment for Pre-forming Holes
Provide the necessary equipment for pre-forming holes on site, including a range of different types of
core barrels of appropriate size, hand auger equipment, sampling tubes with an internal chamfer and
an external diameter slightly larger than the pressuremeter, and borehole callipers.
4
WORKMANSHIP
4.1
Sinking Boreholes
4.1.1
Method of Advancement
Unless otherwise specified, the following methods may be used as appropriate:
(a)
Rotary coring
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(b)
Percussion boring
(c)
Auger boring
Submit proposal of a suitable method to be used and the justification for use to the SO for approval.
The minimum nominal casing diameter shall be 150 mm. At ground level before boring commences,
the initial casing diameter shall be sufficiently large to ensure that the borehole can be completed
to its scheduled depth.
4.1.2
Circulation of Drilling Fluid and Cutting Sedimentation Pits
Locate pits for circulation of drilling fluid and cutting sedimentation away from the borehole, and connect
through trenches, unless otherwise agreed with the SO for other alternative methods due to site
constraint.
4.1.3
Heaving of the Bottom of the Borehole
Control the level of drilling fluid in the borehole at all times to be at least equal to or higher than the
elevation of the groundwater to prevent heave and disturbance of the soil at the bottom of the
borehole. This condition shall be strictly observed in boring through strata comprising sand or coarse
silt, or in operations involving undisturbed sampling and in-situ testing.
In strata comprising soft to very soft soils or when instructed by the SO, use appropriate drilling fluid in
addition to full depth casing to stabilise the borehole. Drilling fluids shall not be used when permeability
tests are to be carried out or piezometers are to be installed in the borehole.
4.1.4
Addition of Water
Do not use water to advance the borehole other than in dry granular soils or otherwise agreed by the
SO.
If water is added to assist with the Works, record the depth when water is added. Maintain a positive
hydraulic head in the borehole where it advances below the water table in cases where disturbance of
the soils is likely.
If boring indicates artesian or sub-artesian groundwater condition in granular soils, immediately add and
maintain a head of water during boring and sampling in order to counteract the disturbance caused by
the removal of overburden or inflow of groundwater.
4.1.5
Obstructions
Use rotary coring method or a method agreed with the SO where a hard stratum or obstruction is
encountered.
Do not continue for more than an hour without informing the SO and obtaining the SOs further
instructions.
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4.1.6
Coring Through Hard Stratum
When hard stratum is encountered, use a core barrel with a diamond-impregnated drill bit or other
methods as agreed with the SO for sampling the stratum. Take samples at the change of such hard
stratum.
4.1.7
Use of Clay Cutters
Clay cutters shall not be used for advancing the boring in soils where they will cause excessive
disturbance in soils to be sampled. Where clay cutters are permitted, they shall be of a type pattern
approved by the SO, and the combined weight of clay cutter and any sinker bar shall not exceed 150
kg.
4.1.8
Continuation of Boreholes
Cover any borehole remaining open overnight. The casing shall be pulled up by about 0.3 m and left
in such position overnight to prevent the entry of rainwater and surface water but allow a free passage
of air into the casing. Before the first sample is taken on the following new day of operation, advance
the boring for at least 0.3 m. In soft soils, a head of water shall be maintained in the casing to
minimise heave of the borehole.
4.1.9
Backfilling of Boreholes
Do not backfill boreholes with soil arisings, unless otherwise agreed with the SO. Backfill all boreholes
with cement bentonite grout, including boreholes for standpipes and piezometers together with their
response zones installed at the depths specified, or as directed by the SO.
Introduce the grout using a tremie pipe which shall be kept below the surface of the grout as filling
proceeds.
Agree with the SO on a suitable method to be used where ground condition is such that normal grouting
is impracticable.
Leave the area in a clean and tidy condition.
4.2
Pits and Trenches
4.2.1
Inspection Pits for Locating Underground Services
Unless otherwise directed by the SO, excavate pit not less than 1.5 m2 by hand to a depth of
1.2 m and hand auger for another 1.8 m, making a total of 3.0 m to locate underground
services.
Use hand-operated power tools where necessary to assist the excavation.
Record the positions, depths and dimensions of all services encountered in the daily reports.
Exploratory holes shall not begin until the present or otherwise of all such services has been
established.
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4.2.2
Trial Pits and Trenches
Excavate pits by hand to a depth of 1.2 m unless otherwise specified, or by machine to the required
depth to enable visual examination and sampling from outside the excavation. Do not allow access to
excavations greater than 1.2 m, unless the pits are shored, or benched or otherwise agreed with the
SO.
4.2.3
Observation Pits and Trenches
Excavate by hand or machine as required. Provide adequate and stable support to enable safe access
for in situ examination, sampling and testing as required. The supports shall be placed so as to
minimise interference with the taking of samples or inspection of the faces. Take all necessary
safety checks, including checking for noxious or toxic gases or materials, or radioactive materials.
4.2.4
Dimensions of Pits and Trenches
Unless otherwise specified,
4.2.5
(a)
Inspection pits as in Section C02-010:Clause:4.2.1 shall have a base area not less than
1.5 m²;
(b)
Trenches other than as in Section C02-010:Clause:4.2.1 shall be 1 m wide.
Groundwater
Keep pits and trenches free from surface water run-off. Control ground water by pumping from a
sump, but take adequate safety measures to maintain the stability of the excavation.
4.2.6
Description of Pits and Trenches
Provide a log with detailed description of the nature of the ground encountered within the excavation,
including:
(a)
the nature of the strata
(b)
the condition of the base
(c)
the presence of any water
(d)
suspected contamination
(e)
any special features
Photograph each face of the excavation to show the details of the ground conditions and any unusual
features identified. Photographs shall be taken or accompanied with a reference information board,
including a colour chart, to show the pit reference number and the orientation of the face being
photographed.
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4.2.7
Sampling from Pits and Trenches
If samples are recovered from trial pits and trenches, the requirements of EN ISO 22475-1 shall be
followed.
For small disturbed samples, samples of not less than 1 kg shall be taken at each change in soil
type, change in consistency with an agreed method or as instructed by the SO. The samples shall
be placed immediately in air-tight containers.
For bulk disturbed samples, representative samples representative of the zone, of not less than 30
kg shall be collected over a depth interval of 0.5 m at specified depths with an agreed method or as
instructed by the SO.
4.2.8
Protection to Excavations Left Open
4.2.8.1
Protection to Personnel
Provide all necessary signing and lighting, together with temporary barriers/fencing.
4.2.8.2
Protection against Inclement Weather
Provide all necessary precautions to protect the excavations from the effects of inclement weather.
4.2.9
Backfilling
Backfill as soon as practicable using excavated material unless otherwise agreed.
Compact with excavation plant or as agreed by the SO and subsequent checks to ensure the area
remains level after filling.
Remove any surplus material from site. Leave the area in a clean and tidy condition.
4.3
Sampling
4.3.1
Sampling by drilling
The drilling equipment for sampling shall be selected according to following:
(a)
Sampling categories required, as defined in SS EN 1997.
(b)
Depth to be reached.
(c)
Required diameter of the sample.
(d)
Functions required from the drilling rig, e.g. recording of the drilling parameters, automatic or manual
adjustment.
The requirements of EN ISO 22475-1 shall be followed.
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4.3.2
Open Tube and Piston Samples
Soil sampling length shall be at least 1 000 mm long to have sufficient sampling length for laboratory
testing.
4.3.3
Frequency of Sampling and Testing
Requirements for the frequency of sampling and testing are given in the Provisional Bill of Quantities in
Section C02-010:Clause:1.4.1 or otherwise instructed by the SO.
Refer to SS EN 1997-2 on the mass of soil required for test on undisturbed samples.
Specific sampling and in-situ testing pattern such as values of Standard Penetration Test (SPT) following
every attempt to take an open-tube or piston sample, shall be approved by the SO.
[Note 1: For establishing correlation between SPT-N value and Undrained Shear Strength, in- situ vane
shear tests shall be carried out in separate borehole in close proximity, at 1 m away.]
4.3.4
Identification, Handling, Transport and Storing of Samples
4.3.4.1
General
Handling, transporting and storing of samples shall be carried out in accordance with EN ISO 224751.
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4.3.4.2
Identification, Storage and Disposal of Samples
Remove all samples from the site of the boreholes at the end of each day's work and protect from
excessive heat by storing on or near the site under cover and secured from interference. Any temporary
store areas on site shall be subject to the SOs approval. Any such store area shall ensure samples are
well protected from excessive heat (>35°C), rain and other elements. Samples shall be accessible
and organised to allow fast location of particular specimens.
Label all samples clearly and identify clearly any material that is or is suspected to be harmful.
Seal, transport and store the samples so that no change in moisture content and soil structure occurs
prior to laboratory testing.
Store all samples in an orderly fashion at site in protective boxes in a dry place and under cover to the
requirements of Section C02-010:Clause:1.4.6 until they are despatched to the designated laboratories
or as directed by the SO.
Remove all samples from the site so as to reach the laboratory within the same day of being taken
unless otherwise agreed.
The thin-walled, stationary piston and Mazier type undisturbed samples shall be stored, protected and
transported with utmost care to avoid disturbance to the samples. They shall be placed and transported
in approved sample containers.
The sample container shall be constructed such that the sample container is padded throughout
with rubber foam and contain partitions to stop the sampler tubes from moving in any direction during
transporting to the laboratory. The rubber foam lining shall have a minimum uncompressed
thickness of 100 mm.
The sample container shall be capable of accommodating a minimum of 3 undisturbed samples and shall
be of strong construction with carrying handles. Prior to the commencement of site work, submit a
sample of the shipping container for approval by the SO.
During transportation, all undisturbed samples shall be protected in the same manner as during storage
on site.
All samples are required to be kept for a period of not less than 3 months after submission of the
approved final report and shall be discarded only with approval by the SO. Give the SO at least 1
week’s notice before the disposal of samples.
4.3.5
Disturbed Samples
Retain disturbed samples at all changes of strata from the cutting shoe of an open tube.
Store these samples in small airtight PVC containers, correctly labelled, and deliver to the SOs
office or other premises as directed by the SO, upon completion of the Work.
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4.3.6
Undisturbed Samples
Take undisturbed samples by thin walled piston or other approved sampler in cohesive materials at
the change of strata and at appropriate intervals as directed by the SO within each type of soil.
Unless otherwise directed by the SO, use a Mazier sampler to obtain stiffer soils where the thin walled
sampler is not able to take undisturbed samples.
4.3.6.1
Recovery and Preservation of Undisturbed Samples
Submit for the SOs acceptance on the recovery, sealing (including wax protection),
preservation, and storage of undisturbed samples immediately following their sampling, to avoid
disturbance to the samples. Carry out the following procedure:
(a)
After the undisturbed sampling, a rubber cap shall be placed on the lower end of the sampling tube
containing the cutting edge. This is to prevent damaging the cutting edge itself.
(b)
From the other end of the sampling tube, about 40 mm of material shall be carefully removed. The material
shall be retained in a screw top clear plastic container and sealed.
(c)
The inside of the tube from its open end to the surface of the undisturbed sample shall be cleared of all soil
debris using special cleaning tools and lightly greased.
(d)
A circular piece of paper having the same diameter as the inside of the sampling tube shall be placed on
top of the sample. This paper is to minimise wax impregnation.
(e)
The inside of the tube to be covered with wax shall be thoroughly degreased and melted non-shrinking
microcrystalline wax shall be poured onto the paper disc to a thickness of about 10 mm.
(f)
Once the wax is nearly solid, a neoprene disc having the same diameter as the inside of the tube shall
be gently pressed into the wax to ensure the wax makes a good seal with the wall of the sampler.
(g)
Another 10 mm thickness of wax shall be poured onto the neoprene disc, and once hardened a final 30 mm
thickness of wax shall be poured onto the sample.
(h)
Once the wax has hardened, moist sand, saw dust or soil shall be placed on the waxed sample to fill
completely the sampling tube.
(i)
A rubber cap shall then be placed on the end of the sample tube and its edge sealed against the outside
of the sample tube with adhesive vinyl tape and wax.
(j)
The tube shall be inverted carefully and steps (b) to (i) repeated for the cutting shoe end of the tube.
(k)
The sample tube shall be labelled in accordance with Section C02-010:Clause:4.3.10.
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(l)
4.3.6.2
Until the samples are removed from the site, they shall be placed in protective boxes in a dry place and
under cover to the requirements of Section C02-010:Clause:1.4.6.
Unsuccessful Sampling
Where an attempt to take an undisturbed sample fails, the boring shall be cleaned out for the full depth
to which the sampling tube has been driven and the recovered soil saved as a disturbed sample. A
fresh attempt shall then be made from the level of the base of the failed attempt. If the second
attempt is still unsuccessful, adopt alternative means of sampling as agreed with the SO.
[Note 1: Consider an alternative method if the sample is less than 70% recovery.]
4.3.7
Standard Penetration Test (SPT) Samples
When a standard penetration test (SPT) is carried out, retain the sample from the split barrel sampler as
a small disturbed sample.
Where no sample is retained, take a bulk disturbed sample or obtain a sample with a Shelby type
Undisturbed (UD) sampler from the test area of similar ground conditions.
4.3.8
Groundwater Samples
Where directed by the SO, take a water sample of not less than 0.25 litres from each water standpipe.
Store each sample in a clean, dry container.
4.3.9
Description of Samples
Examine and describe all samples in accordance with SS EN 1997-2. For weathering classifications
and descriptions of soils and rocks, refer to SS EN1997-2, BS EN ISO 14688-1, BS EN ISO 14688-2
(for soils) and BS EN ISO 14689-1 (for rocks).
4.3.10
Labelling of Samples
All samples, including water shall be labelled immediately after being taken from the borehole or
investigation point. The label shall be clearly and indelibly marked and shall show all the necessary
information about the sample, including:
(a)
Title and reference number
(b)
Date of sampling
(c)
Investigation pit/hole reference number
(d)
Sample reference number
(e)
Depth of sample (including top and bottom of sample)
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The following legend shall be used for the investigation hole/pit and sample reference number:
Rotary wash or percussion boring
BH
Auger borings
HA
Trial pits
TP
Trial trench
TT
Mazier core sample
MZ
Rotary core sample
RS
Stationary piston undisturbed sample
UP
Thin-walled tube undisturbed sample
UT
Open-tube undisturbed sample
UD
Small disturbed sample
DS
Bulk disturbed sample
DB
Ground water sample
WG
Surface water sample
WS
The label shall be securely fixed onto the outside of the sample tube, jar or bag. The outside of the
sample tube, jar or bag shall also be clearly and indelibly marked with the same information as the label.
4.3.11
Recording Depths
Record the depths below ground at which all samples are taken.
For open tube and piston samples, record the depth to the top and bottom of the sample and the
length obtained.
For bulk samples, record the depth of the sample zone.
4.3.12
Rock Cores
4.3.12.1
Equipment for Core Recovery
Unless otherwise specified or directed by the SO, use a triple tube coring system, effected by the use
of a double tube barrel with a semi-rigid liner to be agreed by the SO.
Use triple tube core barrel of NX size or larger, or as directed by the SO to obtain cores of not less than
50 mm diameter in rock.
[Note 1: Although NX is accepted by ISRM, ISRM does suggest a size of at least 54 mm. For rock
cores, size of at least HQ (63.5 mm) is used for purposes including better core quality and sample quality
recovery, more reliable test results, and better recovered joint infilling.]
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4.3.12.2
Recovery of Cores
Produce cores not less than the specified diameter throughout the length of the core.
No drilling run shall exceed 1.5 m in length. Withdraw the core barrel from the hole and remove the core
as often as necessary to secure the highest possible core recovery and quality. Probe rock for a
minimum depth of 5 m by rotary core drilling or continue drilling until not less than 90% total core
recovery is achieved in any 1.5 m run. Core recovery of less than 90% is not acceptable. If the
measured core recovery is less than 90%, the subsequent core run shall be reduced (subject to a
minimum core run length of 0.5 m) and if such measures are not successful, alternative coring
measures shall be proposed for approval by the SO.
The Total Core Recovery (TCR), Solid Core Recovery (SCR), Rock Quality Designation (RQD) and
the Fracture Index (FI) as defined in BS ENISO22475-1 and BS 5930, shall be reported for each core
run.Refer to the definitions listed below:
Term
Definition
Fracture Index (FI)
The number of naturally occurring fractures per metre run of
core.
Solid Core
The intact core having a full diameter without fractures.
Solid Core Recovery (SCR)
Theratio of the total length of the solid core over the drilling run.
Rock Quality Designation (RQD)
The percentage of the total length of solid cores each exceeding
100 mm in length over the drilling run.
Any length of core containing breaks caused during drilling or handling shall be considered as solid when
computing the SCR, RQD and FI.
4.3.12.3
Removal of Cores
Submit for the SOs acceptance a method statement detailing how the core shall be extracted from the
core barrel prior to the commencement of drilling works.
Care shall be exercised to ensure that fractures caused during drilling or extraction of the core from the
core barrel or liner are minimised and those which cannot be avoided are identified and not included
in the assessment of SCR, RQD and Fl.
Carry out all operations so as to minimise disturbance to the cores. Support the core rigidly while the
liner is removed and subsequently as the core is extruded.
4.3.12.4
Marking of Cores
Immediately after removal of the liner, mark both ends in indelible ink or other agreed manner. Cap
and seal the liner, where cores are not to be examined on site. Where cores are taken out, they
shall be indelibly marked and logged on site.
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4.3.12.5
Inspection of Cores
Boxes containing the cores shall be neatly stored at the borehole locations in such a manner that
inspection of the cores can easily be made. Store the boxes under cover and protected from the
weather. Transport all core boxes to avoid damage and disturbance to the contents.
Unexamined core samples contained within plastic lining tubes and waxed samples retained for
testing shall be stiffened with laths of wood and wrapped carefully with foam sheeting to minimise
disturbance during transportation.
4.3.12.6
Storage of cores
Immediately after removal from the core barrel, wrap selected lengths of core in 3 layers of linen
cloth, coat each layer with wax and place the cores in core boxes in a consistent sequence.
Alternative wrapping for the cores is subject to the SOs acceptance.
Store the core boxes on or near the site under cover and secured from public interference.
Core boxes shall be constructed of sound materials such as timber, galvanised steel or reinforced
plastic with a lid having secure fastenings. Handles shall be attached to the core box for lifting. Core
boxes shall not contain more than 50 kg of core. The height of the core boxes shall be compatible
with the diameter of the core to be stored in them.
As the core is extruded, it shall be arranged in the box in proper sequence starting with the shallowest
core on the left side nearest the hinge and then working along the slat and subsequently outwards
towards the clasp. Slat shall be positioned and secured such that the core is restrained from
movement.
Wooden partition blocks not less than 25 mm in thickness shall be placed at the beginning and end of
each box and at the end of each core run. These blocks shall be marked with the depth below ground
level in waterproof marking ink numbers at least 20 mm high and facing the box lid. The box label or
marking shall include information on locality, borehole number, core box number, depth and date.
Core losses shall be shown by wooden blocks or polystyrene of a square cross section to fill the core
space and of a length equal to the core lost. Send all cores to the laboratory as soon as possible after
retrieving from the ground.
4.3.12.7
Testing of cores - Unconfined Compression Strength
Carry out point load test or uniaxial compression strength test on selected core samples as agreed by
the SO at an accredited testing laboratory.
4.4
In-situ Testing
4.4.1
General Requirements
Carry out the in-situ tests in accordance with SS EN 1997-1, SS EN 1997-2 and ISRM guidelines for
tests in rocks, or as directed by the SO.
For the in-situ or field tests, equipment and procedures shall correspond to the requirements in
appropriate parts of EN ISO 22476 or as directed or approved by the SO.
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4.4.2
Equipment Calibration
Calibrate all equipment as required in accordance with the manufacturer’s requirements. Evidence
of calibration shall be provided to the SO. Where evidence is insufficient or if there are reasons to
doubt or suspect that the equipment may need to be recalibrated, carry out the recalibration of the
equipment as directed by the SO.
4.4.2.1
Boreholes
The in-situ tests to be undertaken within boreholes, at the intervals at which they are required (where
given) are specified in Section C02-010:Clause:1.4.1 Provisional Bill of Quantities. The Contractor shall
undertake these tests in accordance with the Provisional Bill of Quantities unless otherwise directed by
the SO.
4.4.2.2
Observation Pits and Trenches
Carry out tests at the observation pits and trenches as indicated in the drawings, and any in- situ tests
such as vane shear, in-situ density, cone penetration tests, soil infiltration test, trial grouting test,
mackintosh probing etc., where provided in the Provisional Bill of Quantities or otherwise required by
the SO.
4.4.3
Standard Penetration Tests
Standard Penetration Tests (SPT) shall be undertaken in accordance with BS EN ISO 22476-3.
4.4.4
Vane Shear Tests
Carry out in-situ vane shear tests in accordance with BS EN ISO 22476-9.
The vane blade size is required to be 130 mm x 65 mm or larger and advanced through cohesive soil
without the assistance of boring.
4.4.5
Pressuremeter Tests
Carry out in-situ pressuremeter tests of the type to be approved by the SO at specified depths or as
determined by the SO.
All pressuremeter tests shall be in accordance with BS EN ISO 22476-4 or other internationally accepted
standards to be agreed with the SO.
4.4.6
Cone Penetration Tests
Carry out in-situ Cone Penetration tests (CPT) and Cone Penetration tests with porewater pressure
measurement (CPTu or piezocone), or any other type of CPTs (e.g. seismic cone or pressuremeter
cone) as required by the SO, in the specified locations.
CPTs (including CPTu) shall be undertaken in accordance with BS EN ISO 22476-1, unless an
alternative standard is agreed with the SO.
Present the following parameters together with the results:
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(a)
Net cone resistance
(b)
Sleeve friction
(c)
Pore pressure
(d)
Friction ratio
(e)
Pore pressure ratio.
Carry out dissipation test in silty/clayey strata where required, at locations and depths to be decided by
the SO. Penetration of the piezocone shall be stopped and excess pore water pressure shall be
allowed to dissipate. During these periods, remove loading on the sounding tubes. Record dissipation of
excess pore pressure on a time scale.
4.4.7
Falling/Rising Head Permeability Tests
Carry out permeability tests at depths in accordance with BS EN ISO 22282-2, and as specified,
or otherwise directed by the SO. Indicate clearly in the interpretation of the results whether a
constant-head or variable-head method has been adopted for the test. For falling head test, the
water level in the borehole shall be raised by adding water to a level agreed as in the drawings and
be allowed to stand for a minimum of 30 minutes to saturate the surrounding soil prior to
commencement of the test.
For rising head tests, the water level in the borehole shall first be lowered by bailing to a level agreed by
the SO. Measure the water level at time period of 10-second intervals or at time period intervals as
agreed by the SO, to obtain a representative record of the fall or rise in the water level relative to time.
The level of the natural groundwater table shall be established at the time of testing. In cases where the
stratum being tested may be partially saturated, the initial part of the test may be repeated a number of
times until a repeatable result is obtained.
[Note 1: The 10-second interval data serves as a guideline.]
4.4.8
Packer Tests
Carry out Packer or water absorption tests in rock to measure water acceptance by in-situ rock mass
under a given pressure in accordance with BS EN ISO 22282-3. Express the results in terms of
Lugeon units. A staged test consisting different water pressures is preferable. Clearly state in each test
location whether the test has been carried out using single or double packers.
4.4.9
Plate Load Tests
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4.4.9.1
General
Carry out the test in accordance with SS EN 1997-2 and BS 1377-9 at depth below the existing
ground level as specific with a minimum plate size of 300 mm in diameter as required by the SO
Load the plate to cause bearing failure by a constant load. The failure load is defined as the load at
which the plate continues to settle at a steady rate or the plate has at least gone through 15% of the
plate width, whichever is the lesser.
Prior to the carrying out of the plate load test, propose for the SOs acceptance the test range and
purpose, giving details on expected or estimated bearing strength and deformation characteristics of
the materials to be tested and the maximum plate load test loading.
Apply the test load by means of a newly calibrated hydraulic jack using kentledge or other method as
accepted by SO.
Provide a certificate of calibration from an accepted testing authority before test commencement.
4.4.9.2
Test Procedure
Load testing shall be of the Maintained Load Method. Loading shall be in increments of producing not
more than one-fifth of the design bearing pressure or smaller steps as agreed. Unloading shall be in
at least three equal steps. Each loading shall be maintained for a minimum period of 5 minutes and
until settlement is stabilised. At the maximum load pressure, the load shall be maintained for a
minimum of 6 hours or as agreed by the SO, and until settlement is stabilised.
The settlement is deemed to stabilise if the rate does not exceed 0.1 mm per hour or in proportion for a
shorter maintaining time.
Throughout the test, make observations of vertical movement of the plate with 2 dial gauges
graduated in 0.025 mm divisions. Place a linear metric scale graduated with the appropriate number
of subdivisions vertically on either side of the plate to allow independent measurement of its vertical
movement with a precise level. Refer to the dial gauge readings on stiff steel beams, the ends of
which shall rest on, or are fixed to reliable supports.
The beam supports shall extend not less than 1 m below ground surface and not be located closer than
two metres from the centre of test plate. Check the elevation of the supports frequently with reference
to a fixed benchmark.
Protect the entire measuring assembly against rain, direct sunlight and other disturbance that might
affect its reliability. Provide all necessary facilities to enable the supervision staff to check readings during
the progress of the test. Keep the test under continuous and competent supervision. Give at least 24
hours’ notice of the commencement of each test.
4.5
Laboratory Tests
Conduct laboratory tests in accordance with SS EN 1997-2, and BS 1377 where the standards are
appropriate and consistent with the SS EN 1997 for soil samples and rock samples.
Where SS EN 1997-2 does not cover the relevant tests, ISRM or other suitable internationally
standards as specified, subject to the SOs approval, shall be used for rock testing.
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4.5.1
Classification Tests
Carry out tests for the classification of soil for the determination of basic physical properties as specified:
4.5.2
(a)
Moisture content (SS EN 1997-2 and BS EN ISO 17892-1)
(b)
Atterberg limits, including liquid limit, plastic limit and plasticity index (SS EN 1997-2 and BS EN ISO
17892-12)
(c)
Bulk density and dry density (SS EN 1997-2 and BS EN ISO 17892-2)
(d)
Particle density or specific gravity (SS EN 1997-2 and BS EN ISO 17892-3)
(e)
Particle size distribution with wet sieving and hydrometer methods (SS EN 1997-2 and BS EN ISO 178924)
(f)
Identification and classification of soil (BS EN ISO 14688-1).
Chemical Tests
Carry out tests for determining the organic matter, chemical substances and corrosivity
properties of soil and water samples as specified in accordance to SS EN 1997-2 and BS 13773:
4.5.3
(a)
Organic matter content (SS EN 1997-2)
(b)
Total sulphate content of soil and sulphate content in 2:1 water-soil extract (SS EN 1997-2)
(c)
pH value of soil (SS EN 1997-2)
(d)
Sulphate content (SS EN 1997-2) and pH value of ground water (BS1377-3)
(e)
Chloride content of soil (SS EN 1997-2).
Compressibility Tests
Carry out one-dimensional consolidation and swelling tests in an oedometer for determining the
consolidation and swelling characteristics of soil when subject to changes in applied vertical effective
stress in accordance with SS EN 1997-2 and BS EN ISO 17892-5.
The loading stages shall typically include a full unload - reload cycle and the number of stages as well
as the loadings required for each stage shall be agreed on with the SO.
4.5.4
Shear Strength Tests
Carry out compression tests for the determination of the shear strength parameters of soils in terms of
total and effective stresses in compliance with the following as appropriate:
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(a)
Consolidated Direct shear test (SS EN 1997-2 and BS EN ISO 17892-10)
(b)
Unconfined compression test (SS EN 1997-2 and BS EN ISO 17892-7)
(c)
Unconsolidated-undrained triaxial compression test by single stage or multistage loading without
measurement of pore pressure (SS EN 1997-2 and BS EN ISO 17892- 8)
(d)
Consolidated-undrained triaxial compression test with measurement of pore pressure (SS EN 1997-2 and
BS EN ISO 17892-9)
(e)
Consolidated-drained triaxial compression test with measurement of pore pressure (SS EN 1997-2 and BS
EN ISO 17892-9).
Agree with the SO, the required cell pressures for triaxial tests and the stress levels required for the
direct shear tests, prior to carrying out the tests.
4.5.5
Strength Tests on Rock Samples
Carry out the following tests for the determination of the shear strength parameters of rocks in compliance
with SS EN 1997-2 and ISRM suggested methods for rock testing as appropriate:
(a)
Uniaxial compression strength test
(b)
Point load test
(c)
Brazilian tensile strength test
(d)
Direct shear strength of rock (intact or along rock joint).
4.6
Instrumentation and Monitoring Requirements
4.6.1
Groundwater in Boreholes
Make careful observations of groundwater conditions and levels daily during each boring operation.
Record the level of the water table in each borehole twice daily: once in the morning before resumption of
boring and once at the end of the day.
If artesian conditions are encountered, agree with the SO on the measures to be adopted.
Record the readings by an electrically operated water level indicator capable of measuring the depth to
water levels of up to 30 m.
4.6.2
Standpipes and Piezometers
Typical installation details for standpipes and piezometers are shown in Figures 1 and 2.
Figure 1. Details of Piezometer Installation
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Figure 2. Typical details of water standpipe installation
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4.6.2.1
Sand filter
Record the volume of the sand filter placed. The response zone formed by the sand filter shall
4.6.3
M
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oe
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ertshe
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raipteboor rpeiheozloem
s eatnedr at idneteprtvhassl anodf 1o
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sp
inidni,c8atm
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gsino, r1dhirre, c2tehdr,b3y hthr,e4ShOr,. 5 hr, 6 hr, 7 hr, 8 hr, 16 hr, 24 hr, or when
the water level has returned to its initial steady level.
Protect the tops of standpipes and piezometers by surface boxes as indicated.
wda.
The water standpipe or piezometer shall be in working condition throughout the monitoring A
r io
p ello
meincitm
l agoefdownaetehrosutrabnedtpwipee norpplae
R
i fyuamnytim
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above to prevent probable mixing up of the intended permeable and
T
s aema pb le sl aoyf egr rso. u n d w a t e r of not less than one litre from the standpipes and piezometer when
i mapk e r m
required.
Unless otherwise agreed, monitor all standpipes and piezometers daily during the fieldwork.
S
o rreth
thecwoa
lynlcaebeal w
an
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i nfcieleldaw
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atiu
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n pole
f tshe
edekd teolivmeer atosuthretlh
eclhienmeiaccahl taensdts.every standpipe and piezometer for a period of one month unless otherwise
specified or agreed with the SO. Give one day's notice to all occupiers on the site on which the The tests
for sulphate content (% S03), chloride content, acidity (pH value) and degree of piezometers and
standpipes are situated.
salinity shall be determined from the same sample.
5
VERIFICATION AND SUBMISSION
5.1
Submissions
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5.1.1
General
Unless agreed by the SO, all investigation reports shall follow the requirements of SS EN 1997- 1
and SS EN 1997-2.
Reference shall be made to SS EN 1997- 2 for information on the use of laboratory and field tests
for geotechnical parameters.
5.1.2
Testing laboratory
Submit the proposed testing laboratories for acceptance during tender.
5.1.3
Field Reports
Submit electronically, a copy of the Daily Site Record on the following working day. For all drilling,
borings, sampling and field tests, the site records, logs and test data or reports shall follow the
requirements of BS EN ISO 22475 (on drilling, sampling and groundwater measurements), BS EN ISO
22476 (on field testing), and BS EN ISO 22282 (on geotechnical investigation and testing) as
appropriate, to include the following:
(a)
Location (chainage where known)
(b)
Borehole number
(c)
Date and times of boring
(d)
Type of plant used
(e)
Diameter of boring casing and core as appropriate
(f)
Depth of base of each stratum from surface
(g)
Description of strata
(h)
Level of the bottom of the casing when each sample is taken or in-situ test carried out or each core run
drilled
(i)
Depths at which all samples were taken and in-situ tests carried out
(j)
Detailed test records
(k)
Level at which water was standing at the commencement and end of each day's work
(l)
All water levels encountered and amount of water added (if any) when boring cohesive soils
(m)
Length of drill runs and the actual lengths of core recovered in each drill run
(n)
Percentage and colour of drilling fluid returns
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5.1.4
(o)
Rotary drilling penetration rate and variations
(p)
Remarks on any matters not referred to the above which may be of value in interpreting and understanding
the ground conditions.
Borehole Logs
Submit 1 copy of the Preliminary Borehole Logs, as preliminary version of borehole logs, for the
preliminary description of the soils and rocks at each borehole. Provide a further copy with complete
list of samples retrieved for laboratory testing within 2 days of the completion of site work at each
borehole.
5.1.5
Field test set-up and data
Submit calculations and sketches of the test set up and method statement for the field tests such as
plate load tests to the SO for approval before commencement of the test.
Engage a suitably experienced, competent and qualified PE to review and endorse all submissions.
Submit all records and plot of load versus deformation characteristics within 24 hours after completion of
the test. Propose format of records and reports for the SOs acceptance.
5.1.6
Laboratory Testing Schedules
Prepare a blank test schedule by considering the provisional quantities in Section C02- 010:Clause:1.4.1,
including the following information:
(a)
Borehole number
(b)
Sample number
(c)
Sample type
(d)
Sample depth and on the other axis the following standard laboratory tests shall be listed:
(i)
Moisture content
(ii)
Atterberg Limits
(iii)
Bulk density and dry density
(iv)
Specific gravity of soil particles
(v)
Particular size distribution by Wet sieving method
(vi)
Particular size distribution by hydrometer method
(vii)
Organic matter content
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(viii)
Sulphate of soil and in sample of water-soil extract
(ix)
pH of soil
(x)
Sulphate and pH of water sample
(xi)
Chloride of soil
(xii)
Oedometer (leave space for pressure range to be specified)
(xiii)
Direct shear test
(xiv)
Unconfined compression test
(xv)
Quick triaxial test on 38mm diameter specimen (leave space for pressure range to be specified)
(xvi)
Consolidated-undrained and consolidated-drained triaxial compression tests on 38mm diameter
specimen (leave space for pressure range to be specified)
(xvii)
Uniaxial compression strength test
(xviii)
Point load test
(xix)
Three blank columns for other tests
Submit these draft schedule sheets to the SO with the preliminary logs.
5.1.7
Ground Investigation Report
5.1.7.1
General
Unless agreed by the SO, Ground Investigation Report as provided in SS EN 1997 shall consist
of the following:
(a)
A presentation of all available geotechnical information, including geological features and relevant data.
(b)
A geotechnical evaluation of the information, stating the assumptions made in the interpretation of the test
results.
The information is required to be presented as 1 report or as separate parts.
Submit digitally or as directed by the SO, of the ground investigation report with verification and
endorsement of accuracy and correctness of the report by an appropriately qualified PE after
completion.
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5.1.7.2
Final Report Content
Submit for the SOs approval the Final Report in a format to be agreed by the SO, which shall contain the
following information, where applicable:
(a)
Factual account and description of the Works, stating the scope and purpose of the Works, including a
description of the site and its topography, site plans and detail, of the planned structure and the stage of
the planning the account is referring to; the names of all parties, specialists and laboratories; dates of field
and laboratory investigations and tests performed; field reconnaissance of the site and the surrounding
area; geology of the site; description of site operations, weather, handling of samples; and tests, including
standards used.
(b)
Documentation and description of the methods, procedures and results, including all relevant findings and
reports of:
(c)
(i)
desk studies
(ii)
field investigations, such as field logs, sampling, field tests and groundwater measurements
(iii)
laboratory tests and results.
Documentation of the evaluation and interpretation of information, including as appropriate:
(i)
the tabulation and graphical presentation of the results of field investigation and laboratory testing
in cross-sections of the ground showing the relevant strata and their boundaries including the
groundwater table in relation to the requirements of the project
(ii)
the values of the geotechnical parameters for each stratum
(iii)
a review of the derived values of geotechnical parameters.
The results of the field and laboratory investigations shall be presented and reported according to the
requirements defined in the EN and/or ISO standards applied in the investigations.
5.1.7.3
Approval of Final Report
Preliminary version of the Final Report shall be submitted to the SO for approval before submission of
the Final Report. Allow the Final Report to be included in the Programme for the SOs approval, and for
revision or amendments as required by the SO.
5.2
Equipment Calibration
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5.2.1
Field Vane Shear Tests
Provide full details of the equipment used as well as calibration record and specimen calculation
sheets.
Submit preliminary results for both virgin and remoulded shear strength to the SO within 24 hours after
completion of the test.
5.2.2
Pressuremeter Tests
Provide full details of the equipment used, its range of operation, including maximum depth below
ground level and calibrations record together with specimen calculation sheets.
Submit preliminary results for both initial loading and reloading cycles to the SO within 24 hours
after completion of the test.
5.3
Media Labelling, Data Checking and Virus Protection
5.3.1
General
Clearly label all files, media and conventions.
For AGS (SG) format data, all media are required to be properly labelled and clearly marked with the
following:
5.3.2
(a)
Title âAGS(SG) Format Dataâ
(b)
Project identification (PROJ_ID)
(c)
Project Location (PROJ_LOC)
(d)
Number of boreholes / CPT tests / trial pits
(e)
Date of Project (PROJ_DATE)
(f)
Name of the Contractor or Firm
(g)
Name of the Client
(h)
Version: AGS (SG)
(i)
Reference number of digital storage and retrieval devices or suitable devices
Data Checking
Check and be responsible to provide true, correct and accurate data. Data format and integrity, data
completeness and data validation checks shall be carried out on each data set issued or received prior
to submission. For geo-information, validate the data. Any shortfalls shall be corrected accordingly
before submission to the SO.
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5.3.3
Virus Protection
All electronic data files shall be virus-free. Precluding executable files from the data set reduces the
risk of virus transfer. Scan each data set medium with virus-checking programme prior to submission
to the SO.
5.3.4
Data Submission
Provide and submit a soft copy of the media containing electronic data which shall be the current
electronic copies of all data, preliminary or final. The electronic copies of data, being submitted in
suitable digital storage and retrieval devices, shall be labelled âPRELIMINARYâ or âFINALâ as
appropriate.
APPENDIX 1
Provisional Bill of Quantities for Works to be carried out for ground investigation
Provisional Schedule of Works
Item
Description
Qty
Unit
.
1
FIELD WORK
.
.
.
1.1
Mobilisation and Demobilisation
Provide drilling rigs, all necessary equipment
and crew on the Site and remove upon
completion, including moving rigs and
equipment between borehole position. The
required number of plants/rigs shall be
substantiated with the actual productivity of the
plants/rigs in relation to the deadline.
.
Item
.
1.2
Authority Approval
.
Obtain approval from authorities, including LTA,
HDB, JTC, NParks, NEA, BCA, SLA,
SCDF, etc. and all other necessary clearances.
Item
.
1.3
Specialist/Professional Attendance on Site
Provide suitably experienced, competent and
qualified specialist personnel, including
engineering geologists full-time on site during
site operations to ensure quality work,
compliance with specification and taking site
instructions, ensuring consistent and correct
logging according to specified standards.
.
Item
.
1.4
Erosion Control Measures
Provide adequate erosion control and water
quality throughout duration of the
Investigation Works.
.
Item
.
2
EXPLORATORY HOLES
.
.
.
2.1
Movement on Land
Move the boring plant to the designated
borehole position (including site clearance,
erection of temporary platform if necessary,
etc.), setting out of borehole position by
registered surveyors and including
dismantling it after completion.
.
No.
.
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2.2
Movement over Water / Tidal Range / Swamp .
Move the boring plant to the designated
borehole position (including site clearance,
erection of temporary platform if necessary,
etc.), setting out of borehole position by
registered surveyors and including
dismantling it after completion.
No.
.
2.3
Boring in Soil on Land / Over Water / Tidal
Range / Swamp Wash boring with casing
Carry out wash boring cased at depth from
existing ground level to not exceeding 20 m.
.
a
Ditto - 20 m to 40 m
.
m
.
b
Ditto - exceeding 40 m
.
m
.
2.4
.
Boring in Soil on Land / Over Water / Tidal
Range / Swamp Boring with bentonite
Carry out boring with bentonite as stabilising
fluid cased at depth from existing ground level to
not exceeding 20 m.
m
.
a
Ditto - 20 m to 40 m
.
m
.
b
Ditto - 40 m to 60 m
.
m
.
c
Ditto - exceeding 60 m
.
m
.
2.5
Boring in Soil on Land / Over Water / Tidal
Range / Swamp Boring with polymer
Carry out boring with polymer as stabilising fluid
cased at depth from existing ground level to
not exceeding 20 m
.
m
.
a
Ditto - 20 m to 40 m
.
m
.
b
Ditto - 40 m to 60 m
.
m
.
c
Ditto - exceeding 60 m
.
m
.
2.6
Boring in Soil on Land / Over Water /
Tidal Range / Swamp Boring with foam
Carry out boring with foam as stabilising fluid
cased at depth from existing ground level to
not exceeding 20 m.
.
m
.
a
Ditto - 20 m to 40 m
.
m
.
b
Ditto - 40 m to 60 m
.
m
.
c
Ditto - exceeding 60 m
.
m
.
2.7
Boring on Land / Over Water / Tidal Range /
Swamp Diamond Drilling
Diamond drilling in NX Size or larger
boreholes in solid rock and other hard
materials with SPT "N"values not less than
100 blows / 300 mm using triple tube core
barrel to obtain cores of not less than 50
mm diameter, storing cores in core boxes,
including delivery of cores in core boxes to the
SO and taking of photographs at depth from
existing ground level to depth not exceeding
20 m.
.
m
.
a
Ditto20 m to40 m
.
m
.
b
Ditto - 40 m to 60 m
.
m
.
.
m
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c
Ditto - exceeding 60 m
.
m
.
2.8
Standard Penetration Test
Carry out Standard Penetration Tests (SPT),
including collection of disturbed samples at
depths.
.
No.
.
2.9
Disturbed Samples
.
Take disturbed samples storing in airtight
polythene jars correctly labelled and delivering
to the SO, from existing ground level to not
exceeding 20 m.
No.
.
a
Ditto 20 m to 40 m
.
No.
.
b
Ditto - 40 m to 60 m
.
No.
.
c
Ditto - exceeding 60 m
.
No.
.
.
Undisturbed Sampling with Piston Sampler
Take samples of not less than 75 mm in
diameter and 1000 mm in length, using thinwalled piston sampler completely sealed either
with caps and waterproof adhesive tape or
with paraffin wax for depth from existing
ground level to not exceeding 20 m, and deliver
to an approved laboratory for testing.
No.
.
2.10
a
Ditto - 20 m to 40 m
.
No.
.
b
Ditto - 40 m to 60 m
.
No.
.
c
Ditto - exceeding 60 m
.
No.
.
2.11
.
Undisturbed Sampling with Thin Wall Tube
Take samples of not less than 75 mm
diameter and 1000 mm length using thinwalled open tube sampler or other sampler,
approved by the SO, completely sealed either
with caps and waterproof adhesive tape or
paraffin wax for depth from existing ground
level to not exceeding 20 m, and deliver to an
approved laboratory for testing.
No.
.
a
Ditto - 20 m to 40 m
.
No.
.
b
Ditto - 40 m to 60 m
.
No.
.
c
Ditto - exceeding 60 m
.
No.
.
Undisturbed Sampling with Mazier Sampler
Take samples of not less than 75 mm
diameter and 400 mm length using triple
tube core barrel with retractable shoe(
Mazier sampler), completely sealed either
with caps and waterproof adhesive tape or
paraffin wax for depth from existing ground
level to not exceeding 20 m, and deliver to an
approved laboratory for testing.
.
No.
.
a
Ditto - 20 m to 40 m
.
No.
.
b
Ditto - 40 m to 60 m
.
No.
.
c
Ditto - exceeding 60 m
.
No.
.
2.13
Undisturbed Sample Storage Box Provide
sufficient UD storage box for
recovered UD samples to the specification.
.
No.
.
2.12
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2.14
.
Piezocone on Land
Move equipment from one position to the next,
setting out of position by qualified surveyors and
including dismantling it after completion.
No.
.
2.15
Piezocone over Water / Tidal Range / Swamp .
Move equipment from one piezocone position
to the next, setting out of piezocone position by
qualified surveyors and including dismantling it
after completion. The platform must be stable
and shall not sway or move under disturbance
from water, test equipment and personnel
working on it. The platform shall be approved
by the SO. (Floating pontoon shall not be
used).
No.
.
2.16
Deep Sounding Test
Carry out deep sounding tests at depth from
existing level to not exceeding 15 m
.
m
.
a
Ditto 15 m to30 m
.
.
.
b
Ditto 30 m to50 m
.
.
.
c
Ditto exceeding 50 m
.
.
.
2.17
Dissipation Tests
Carry out Dissipation Tests
.
Vane Shear Test on Land
Move equipment from one position to the next,
setting out position by qualified surveyors and
including dismantling after completion.
.
2.19
Vane Shear Test over Water / Tidal Range /
Swamp
Move equipment from one position to the next,
setting out position by qualified surveyors and
including dismantling after completion.
.
No.
.
2.20
Carry out in-situ Vane Shear Test at depth
from existing ground to not exceeding 20 m.
.
No.
.
a
Ditto - 20 m to 40 m
.
No.
.
b
Ditto - 40 m to 60 m
.
No.
.
c
Ditto - exceeding 60 m
.
No.
.
2.21
Borehole Vane Shear Test on Land Move
equipment from one position to the next,
setting out position by qualified surveyors
and including dismantling after completion.
.
No.
.
2.22
Borehole Vane Shear Test over Water / Tidal
Range / Swamp
Move equipment from one position to the next,
setting out position by qualified surveyors and
including dismantling after completion.
.
No.
.
2.23
Borehole Vane Shear Test over Water / Tidal
Range / Swamp
Carry out in-situ Borehole Vane Shear Test at
depth from existing ground to not exceeding
20 m.
.
No.
.
a
Ditto - 20 m to 40 m
.
No.
.
2.18
.
.
No.
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b
Ditto - 40 m to 60 m
.
2.24
Mackintosh Probe on Land
a.Setting out of location by a qualified
surveyor, setting up, dismantling and moving
the equipment to the next location. b.Carry out
Mackintosh Probes tests as per specification.
.
2.25
No.
.
.
No.
Mackintosh Probe over Water / Tidal Range
.
/ Swamp
a.Setting out of location by a qualified surveyor
setting up, dismantling and moving the
equipment to the next location.
b.Carry out Mackintosh Probes tests as per
specification.
.
No.
Hand Auger
Carry out hand augers, including the provision
of sealed disturbed samples.
.
2.28
Trial Pits
Carry out trial pits as per specification, on land,
at depth not exceeding 3 m.
.
.
.
a
Ditto - for depth exceeding 3 m but not
exceeding 5 m.
.
.
.
2.29
Disturbed Samples
Take bulk disturbed samples of not less than
30kg, store in airtight polythene bags correctly
labelled and deliver to SO's office.
.
No.
.
2.30
Disturbed Samples for Water Content
Determination
Collect a set of 2 sealed samples for
determination of in-situ water content at the
laboratory (testing measured separately) for
every sampling in bulk.
.
Set
.
2.31
Pressuremeter Test
In-situ Pressuremeter test down to the
depths not exceeding 20 m.
.
a
Ditto - 20 m to 30 m
.
No.
.
b
Ditto - 30 m to 40 m
.
No.
.
c
Ditto - exceeding 40 m
.
No.
.
2.32
Ground Water
Take recordings of water levels in all
boreholes twice daily throughout the period of
ground investigation.
.
Supply and install standpipe with protective
surface box to a depth not exceeding 15 m in
borehole, commissioning and taking readings
twice daily for duration of field work and weekly
for one month upon completion of field work.
.
Supply and install standpipe with protective
surface box to a depth (15 m to 25 m) in
borehole, commissioning and taking readings
twice daily for duration of field work and weekly
for one month upon completion of field work.
.
2.27
a
b
.
m
.
No.
.
Item
.
No.
No.
.
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c
Supply and install standpipe with protective
surface box to a depth exceeding 25 m in
borehole, commissioning and taking readings
twice daily for duration of field work and weekly
for one month upon completion of field work.
.
No.
.
d
Supplying and install piezometer with
protective surface box, to a depth of not
exceeding 30 m in borehole, commissioning
and taking readings twice daily for duration of
field work and weekly for one month upon
completion of field work.
.
No.
.
2.33
Groundwater Samples from Borehole Take
sample of ground water of not less than 1 litre
from borehole, storing in clean sealed
container and delivering to an approved
laboratory for testing.
.
2.34
.
No.
.
Groundwater Samples from Standpipe/
.
Piezometer
Take sample of ground water of not less than 1
litre from standpipe and piezometer, storing in
clean sealed container and delivering to an
approved laboratory for testing.
No.
.
Item
Description
Qty
Unit
.
3
LABORATORY TESTS
.
.
.
3.1
Moisture content determination
.
Set
.
3.2
Atterberg limits determination (set of one liquid
limit and one plastic limit)
.
Set
.
3.3
Bulk and dry density determination
.
Set
.
3.4
Specific gravity determination
.
No.
.
3.5
Particle size analysis by sieving only
.
No.
.
3.6
Particle size analysis by sieving plus
sedimentation (hydrometer)
.
No.
.
3.7
Determination of pH, sulphate content and
salinity of sea/ground water
.
Set
.
3.8
Determination of chloride content of sea/ground
water
.
No.
.
3.9
Determination of pH of soil
.
No.
.
3.10
Determination of organic matter content of soil
.
No.
.
3.11
Determination of total sulphate content of soil
.
No.
.
3.12
Determination of sulphate content of aqueous
soil extract
.
No.
.
3.13
Determination of chloride content of soil
.
No.
.
3.14
Constant Head Triaxial Permeability Test for
determination of co-efficient of permeability
.
No.
.
3.15
Consolidation test (oedometer).
.
No.
.
3.16
Consolidated Direct shear test on a set of 3
compacted specimens (60 mm x60 mm).
.
No.
.
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3.17
Consolidated Drained Direct Shear Box Test
with multiple reversal and re-shearing on a set
of 3 reconstituted specimens (60 mm x 60
mm)
.
No.
.
3.18
Unconsolidated undrained triaxial
compression test on one 38mm diameter x 75
mm specimen.
.
No.
.
3.19
Unconsolidated undrained triaxial
compression test on one 50 mm diameter x 75
mm specimen.
.
No.
.
3.20
Unconsolidated undrained triaxial
compression test on one 70 mm diameter x 75
mm specimen.
.
No.
.
a
Single-stage test (test at one cell pressure only
0.5Ïâ or 1.0Ïâ or 2Ïâ using single (1) sample).
.
Set
.
b
Three-stage tests (set of 3 tests of three cell
pressure 0.5Ïâ, 1.0Ïâ, 2Ïâ using single (1)
sample).
.
Set
.
c
Three-stage tests (set of 3 tests of three cell
pressure 0.5Ïâ, 1.0Ïâ, 2Ïâ using three (3)
independent samples.
.
Set
.
3.21
Consolidated undrained triaxial compression test .
with pore water pressure measurement on one
38mm diameter x 75 mm specimen, including
submission of digital photographs of the
undisturbed samples before and after shearing,
digital files on stress path data and other
relevant tests data.
No.
.
3.22
Consolidated undrained triaxial compression test .
with pore water pressure measurement on one
50 mm diameter x 75 mm specimen, including
submission of digital photographs of the
undisturbed samples before and after shearing,
digital files on stress path data and other
relevant tests data.
No.
.
3.23
Consolidated undrained triaxial compression test .
with pore water pressure measurement on one
70 mm diameter x 75 mm specimen, including
submission of digital photographs of the
undisturbed samples before and after shearing,
digital files on stress path data and other
relevant tests data.
No.
.
a
Single-stage test(test at one cell pressure
only 0.5Ïâ or 1.0Ïâ or 2Ïâ using single (1)
sample).
.
Set
.
b
Three-stage tests (set of 3 tests of three cell
pressure 0.5Ïâ, 1.0Ïâ, 2Ïâ using single (1)
sample).
.
Set
.
c
Three-stage tests (set of 3 tests of three cell
pressure 0.5Ïâ, 1.0Ïâ, 2Ïâ using three (3)
independent samples.
.
Set
.
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3.24
Consolidated drained triaxial compression
test (CID) with pore water pressure
measurement on one 38mm diameter x 75
mm specimen, including submission of
digital photographs of the undisturbed
samples before and after shearing, digital
files on stress path data and other relevant
tests data.
.
No.
.
3.25
Consolidated drained triaxial compression test
(CID) with pore water pressure measurement
on one 50 mm diameter x 75 mm specimen,
including submission of digital photographs of
the undisturbed samples before and after
shearing, digital files on stress path data and
other relevant tests data.
.
No.
.
3.26
Consolidated drained triaxial compression test
(CID) with pore water pressure measurement
on one 70 mm diameter x 75 mm specimen,
including submission of digital photographs of
the undisturbed samples before and after
shearing, digital files on stress path data and
other relevant tests data.
.
No.
.
a
Single stage test (test at one-cell pressure only
0.5Ïâ or 1.0Ïâ or 2Ïâ using single (1) sample).
.
Set
.
b
Three-stage tests (set of 3 tests of three-cell
pressure 0.5Ïâ, 1.0Ïâ, 2Ïâ using single (1)
sample).
.
Set
.
c
Three-stage tests (set of 3 tests of three-cell
pressure 0.5Ïâ, 1.0Ïâ, 2Ïâ using 3
independent samples.
.
Set
.
3.27
Unconfined compression test on soil (including
preparation of specimen from sampling tube or
borehole core and presentation of
load/deformation plot).
.
No.
.
3.28
Uniaxial compression strength test without
measurement of Poisson Ratio and Elastic
Modulus on rock (including preparation of
specimen from borehole core and
presentation of load/deformation plot).
.
No.
.
3.29
Uniaxial compression strength test with
measurement of Poisson Ratio and Elastic
Modulus on rock (including preparation of
specimen from borehole core and
presentation of load/deformation plot).
.
No.
.
3.30
Point load test on rock from borehole (rock core). .
No.
.
3.31
Soil Compaction Test (Proctor Test) Carry
out compaction test on remoulded samples:
.
.
.
a
With a 2.5 kg Hammer
.
Set
.
b
With a 4.5 kg Hammer
.
Set
.
4
REPORT
.
.
.
TS 185/1065
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4.1
Allow for digital photographs with resolution (1600 .
x 1200) pixels per frame showing boring rigs
at all borehole locations, extruded undisturbed
samples and rock cores with labelling and
colour reference strip, stored in suitable digital
storage and retrieval devices to be agreed by
the SO.
Copy
.
4.2
Provision of the Final Report (including asbuilt survey endorsed by licensed surveyor) and
2 sets of soft copies(in suitable digital storage
and retrieval devices) containing all SI data in
AGS format (in accordance to the Specification
for AGS format) and soft copy of the as-built
survey plan. This is inclusive of daily
investigation field records, reports, findings,
logs or data, etc.
.
Copy
.
[Note 1: Provide a list showing provisional quantum of works to be carried out for the ground
investigation, including in-situ tests, laboratory tests, sampling of soils and rocks, water level
monitoring, etc.
Note 2: In addition, provide a schedule of exploratory holes that tabulates provisional quantum of
exploratory holes to be carried out (including boreholes, CPTs, trial pits, etc.) and where applicable,
the requirements for sampling, in-situ testing and instrumentation in each hole.]
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(5) C02-020 General Earthworks (Excavation and Filling)
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1
GENERAL
Read this Section with G01-010 "General Requirements" and all other contract documents.
1.1
Scope
This Section covers the requirements for the following general earthworks items for building works:
(a)
Excavation
(b)
Filling and Embankments
(c)
Site-won and imported fill materials
(d)
Rock-fill
This Section does not cover ground improvement beneath an earth structure, dredging and land
reclamation earthworks.
1.2
Related Sections
Read this Section in conjunction with the relevant requirements of the following sections:
1.3
C01-020
Condition Survey
C02-010
Ground Investigation
C02-030-1
Diaphragm Wall
C02-030-2
Sheet Piling
C02-030-3
Contiguous Bored Pile Walls and Secant Pile Walls
C02-050
Instrumentation and Monitoring
Standards, Codes, Regulations and Technical References
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1.3.1
Standards and Codes
Unless otherwise agreed by the SO, ensure all of the Works comply with the relevant requirements of
the Standards and Codes listed below or referenced in the body of the Specification. Alternative
Standards and Codes may be proposed for approval by the SO, provided it can be demonstrated that
the alternative Standards and Codes comply with the requirements of the standards specified. All
Standards and Codes quoted are the current version, unless specific year references are noted.
In the event that the standards or codes are partially superseded or have become obsolete, refer to
the current edition or the approved substitution for the relevant clauses.
Singapore Standards
SS EN 1997-1
Eurocode 7: Geotechnical Design - Part 1: General Rules
SS EN 1997-2
Eurocode 7: Geotechnical Design - Part 2: Ground Investigation and
Testing
NA to SS EN 1997-1
Singapore National Annex to Eurocode 7: Geotechnical design - Part
1: General rules
NA to SS EN 1997-2
Singapore National Annex to Eurocode 7: Geotechnical design - Part
2: Ground investigation and testing
SS EN 1992-1-1
Design of concrete structures, Part 1-1 General rules and rules for
buildings
SS EN 1993-1-1
Eurocode 3 - Design of steel structures - Part 1-1General rules and
rules for buildings
SS CP 4
Foundations
SS CP 79
Safety management system for construction worksites
SS 31
Aggregate from natural sources for concrete
SS 593
Code of Practice for Pollution Control
Other Standards
BS EN 16907-1
Earthworks - Part 1: Principles and general rules
BS EN 16907-2
Earthworks - Part 2: Classification of materials
BS EN 16907-3
Earthworks - Part 3: Construction procedures
BS EN 16907-4
Earthworks - Part 4: Soil treatment with lime and/or hydraulic
binders
BS EN 16907-5
Earthworks - Part 5: Quality control
BS EN 16907-6
Earthworks - Part 6: Land reclamation earthworks using dredged
hydraulic fill
BS EN ISO 22476
Geotechnical investigation and testing. Field testing.
BS EN ISO 22282
Geotechnical investigation and testing. Geohydraulic testing.
BS 3882
Specification for topsoil
BS 6031
Code of practice for earthworks
BS 8002
Code of practice for earth retaining structures
BS 8004
Code of practice for foundations
BS 5835-1
Recommendations for testing of aggregates. Compactibility test for
graded aggregates
TS 189/1065
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1.3.2
Technical References
Refer to the following technical references for guidance in carrying out the Works:
(a)
BRE Digest 251(1995) Assessment of damage in low rise building
(b)
Jurong Town Council (JTC), Guidelines on Environmental Baseline Study (EBS) (2019 Edition)
(c)
CIRIA C760 Guidance on embedded retaining wall design
(d)
Singapore, TR26 Technical Reference for Deep Excavation
1.4
Trade Preamble
1.4.1
Contractor’s Submissions and Proposals
1.4.1.1
Design for Temporary Works
Engage a qualified, competent and suitably experienced PE to carry out the following:
(a)
Design and supervise the temporary works, if necessary, and precautionary measures, including earth
retaining and stabilising structures e.g., temporary stabilising slope, retaining structures and supports for
stability of the earthworks.
(b)
Prepare a response plan in the event that the temporary works do not perform as expected in the design.
(c)
Prepare and submit all designs, including drawings to the SO and the authorities for approval where
applicable, before the commencement of temporary works.
Submit the curriculum vitae (CV) of the PE to the SO for acceptance.
[Note 1: Identify temporary works and submit the design and drawings early before the commencement
of the main work.]
1.4.1.2
Impact Assessment
Engage a qualified, competent and suitably experienced PE to carry out an Impact Assessment on
the effects of ground movement to the neighbouring properties due to the works, for the purpose of
establishing permissible limiting suitable values as appropriate, for monitoring for alerts, review and
suspension of work in complying with the regulating requirements, including Building Control Act and
Regulations, or as directed by the SO. Submit the report with endorsement from the PE to the SO for
acceptance.
Refer to the current advisory, guides and requirements issued by the Commissioner of Building
Control.
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1.4.1.3
Equipment and Methods
Propose suitable equipment and methods to carry out the Works. Detailed method statements, and
construction sequences, and construction schedule shall be included with the submission to the SO for
acceptance.
The method statements shall include full details of the methods to ensure adherence to the following:
1.4.1.4
(a)
Quality control, which shall be in accordance with the quality control plan in C02- 020:Clause:1.4.14
(b)
Health, safety and environmental requirements
Temporary Diversion of Services
Where applicable, propose schemes and details for the temporary diversion of existing above ground or
underground services to facilitate the works.
1.4.2
Contractor’s Responsibility
The earthworks shall be executed and undertaken strictly in accordance with the relevant local
regulations and by-laws that are current at the date of the tender together with all amendments and
addenda which are imposed as statutory requirements in the course of the Works. Provide for all things
necessary for compliance with the requirements of this Section and to complete the Works. Provide all
necessary and safe temporary works required for the purpose of and to complete the earthworks. This
shall include conducting ground investigations, preparing adequate designs, making statutory
submissions, constructing, testing, monitoring and subsequently removing all necessary temporary
works to the satisfaction of the SO and the relevant authorities.
Unless endorsed by the PE and agreed with the SO, the Works shall not deviate from the designs,
method statements and construction sequences for the temporary works. Strictly adhere to the use of
good workmanship, proven construction techniques and timely implementation of agreed construction
method and sequence to limit ground loss and movement next to the excavation.
1.4.3
Co-ordination with Other Works
Co-ordinate with other contractors who may carry out other works at, or around, the same time at the
Site, as well as parties who undertake preliminary works prior to commencement of the Works and
those who take ownership of the site following completion of the Works. Take into account site
access, space occupation, safety and safeguarding of adjoining properties and each other’s works.
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1.4.4
Condition Survey
Where applicable, prior to and upon completion of the Site Works, carry out a condition survey to
adjacent buildings in accordance with the requirements of Section C01-020. Submit all records to
the SO and adjacent property owners where directed.
Keep a copy of the survey report on site ready for inspection.
For each adjacent building or facility, a set of photographic records together with proper
documentation and a schedule listing the size of the superstructure, extent of underground structure,
visible defects with measurement and any other relevant details pertaining to the general condition
of that building or facility are required. In the case where blasting is used, prior to commencing
blasting operations, submit a written report listing any existing defects in the structures in the zone
which may be affected, supported by photographs where necessary, to the SO.
1.4.5
Instrumentation and Monitoring
Provide instrumentation to monitor the ground movement, vibration and condition of adjacent
properties. Refer to Section C02-050:Clause:3.1, and the drawings for the schedule of
instrumentation required. If necessary or as required by the authorities, propose and provide additional
instrumentation and monitoring for record. The method of construction shall comply with the more
severe of either the statutory limits imposed on lateral and vertical ground movements, construction
noise, vibration and air pollution levels, or such limits necessary for the adequate protection and proper
functioning of neighbouring roadways, buildings and facilities as agreed with the SO.
Take cognisance of and co-ordinate with other contractors on site who may be carrying out
instrumentation and monitoring works to avoid duplication of installation and readings.
For general requirements of the instrumentation and monitoring works refer to Section C02- 050
"Instrumentation and Monitoring".
1.4.6
Upholding of Adjoining Properties
Accept responsibility for the upholding of the adjoining buildings and roads, footpaths etc., where
applicable, together with the mains and services from the time of taking possession of the Site
through the duration of the Works.
Adequately maintain roads and footpaths within and adjacent to the site and keep clear of mud and
debris.
Where temporary works will cause alterations to the permanent structure, such as changes in the
design loadings to accommodate construction loads, provision of temporary construction openings,
incorporation of the temporary works or part thereof into the permanent structure etc., complete
revised designs and details of the affected permanent work certified by the PE, shall be provided.
Revised designs of the permanent structure shall comply with the requirements of these
specifications and shall be in general conformance with the design concept of the permanent
structure, all to the satisfaction of the SO.
1.4.7
Verification of Site Information
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1.4.7.1
Site Surveys
Verify and be satisfied that the information given in the existing site survey plans provided are accurate. If
necessary, engage a Registered Surveyor to carry out additional site survey before commencing any
work.
1.4.7.2
Additional Site Investigation
Take all necessary steps before the commencement of earthworks to verify and supplement the
ground investigation report and any other information provided at tender, to the extent that is required
in the method of construction.
Consider all relevant factors, including those arising from the nature of the ground (e.g., ground
levels, water table level, rock formations, subsoil conditions, etc.), geology of the Site, climatic
conditions, the availability or lack of access, working space, storage, accommodation, the proximity of
adjoining structures and roads, the local regulations regarding the obstruction of public highways and
any other limitations imposed by the Site and its surroundings, for the satisfactory completion of the
earthworks. Make due allowance for the effect of these constraints on the Contractor’s construction
operations to ensure on-time completion of the Works.
Carry out additional ground investigation where additional information is needed for the works or when
directed by the SO. Carry out the Works in compliance with Section C02-010 and EN 16907-1 to 6,
which describe investigation and testing methods specific to earthworks.
Carry out the exploratory holes and any testing progressively prior to commencement of the Works in
areas according to the Contractor’s construction programme. On completion of drilling, backfill the
boreholes with a suitable bentonite/cement mix. Backfilling of trial pits may be undertaken with the pit
arisings subject to the SOs approval, on the condition that it is safe to do so, and the arisings shall be
placed and compacted in layers to ensure any settlement is within acceptable levels. Should
settlement of the backfilled trial pits be considered a risk, the site shall be revisited at a later date(s) as
agreed with the SO to check the pit locations and, where necessary, to top up and level off the
ground to the satisfaction of the SO.
Submit the location and schedule for the boreholes with the SOs acceptance prior to carrying out the
Works. On completion, prepare the ground investigation report and submit to the SO for acceptance.
1.4.7.3
Groundwater Level
Verify the data on groundwater level from available ground investigation reports and where possible,
continue groundwater monitoring on existing installations, in addition to installing new groundwater
monitoring wells and piezometers, and commencing monitoring of these installations.
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1.4.7.4
Contamination
Verify information on contamination identified or believed to be present on site. Environmental Baseline
Studies (EBS) or Environmental Site Assessment (ESA) in compliance with the requirements of
relevant authorities as appropriate, shall be undertaken to investigate or verify contamination of soil and
groundwater.
In the event that contamination is either positively identified or suspected, draw to the attention of all
personnel working on site together with the need to take any precautionary measures in handling
contaminated materials, groundwater and obnoxious vapours from the ground.
[Note 1: Contamination of soil and groundwater shall be verified or investigated in accordance with JTC’s
guidelines on EBS or ESA, and relevant requirements by authorities including SLA and NEA.
Note 2: Contamination may have been previously identified or suspected from the past history of the
Site. In either case, details should be given, and even where no such information is available the
Contractor should notify the SO of any relevant findings and take appropriate precautions while
working on the Site.]
1.4.8
Existing Services Affected by the Works
Refer to G01-010 "General Requirements" for the requirements to deal with existing services affected by
the Works.
Conduct pre-commencement site visits where necessary to establish and verify the locations and
levels of all existing underground utilities within and surrounding the Site that are affected by the
earthworks, and take all necessary steps either of a temporary or a permanent nature to protect, divert
or shut off the affected services to the satisfaction of the relevant authorities or service providers.
Any information made available at the time of the tender is indicative and is intended only as an
approximate guide for verification on site. Immediately after taking possession of the Site and before
commencing work, establish test holes to confirm the locations and levels of all existing
underground utilities within and surrounding the Site that are affected by excavation works. If the site
verification survey of underground services is incomplete or inadequate in any way, additional
confirmatory test holes shall be carried out as directed by the SO. Immediately notify the SO and
the relevant authority if encountering services not known to have existed at the time of tender.
1.4.9
Site Protection
Protect all equipment and working area using fencing or other methods as accepted.
Upon completion of construction operations, remove all temporary works to the satisfaction of the SO
and to the requirement of the relevant authority. Provide approved fill material, transport, deposit in
voids between the face of the excavation and the permanent structure, and compact to the required
lines, levels and grades required for the satisfactory completion of the earthworks. Propose for the SOs
acceptance on the use surplus excavated materials as fill provided the material meets the
requirements of these Specifications.
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1.4.10
Temporary Access Roads
Provide and maintain all necessary temporary access roads and divert and reinstate the permanent
drainage system.
Submit the proposed alignments and levels of temporary access roads to the SO for approval prior to
their construction.
Provide all temporary roads with drainage ditches over the full length of the roads.
All temporary works, e.g., temporary cut, fill, retaining structures, strengthening measures, etc., that will
be left behind and form part of the permanent works shall comply with the requirements, standards,
specifications, safety standards and serviceability conditions as the similar types for permanent works.
Obtain all necessary statutory approvals on temporary access into the Site for the tenure of the contract
period and comply strictly and diligently with all conditions attached with these approvals. The access as
well as the portion of public road and walkway connected with it shall be kept clean and safe at all times.
Provide continuous and adequate security arrangements at access points into the Site for the full
duration of the Contract.
1.4.11
Obstructions
The submission of the tender shall take full account of the Site, including site visits, the nature, extent
and practicality of the excavation, earthworks or associated temporary works. Prior to the submission
of the tender, check and verify that the existing ground and formation levels as shown on the
drawings are correct.
If any obstructions such as existing fences, structures, footings, boulders, concrete blocks, pipes,
drains, driveways or ramps are encountered during excavation, submit proposals for their removal
for the SO's acceptance.
Regardless whether or not the service to be diverted is known to exist at the time of tender, give the
necessary notices to the relevant authority or service provider and arrange for the diversion work to
be carried out if required or as directed by the SO and the relevant authority or service provider to
temporarily or permanently divert any cable, pipe or other services.
Co-ordinate all service diversion works that are carried out during the tenure of the Contract Period to
ensure that such works do not adversely affect the on-time completion of the Works, and bear all
consequences for any delay arising from failure to do so.
1.4.12
Supervision of the Works
Engage a qualified, competent and suitably experienced site engineer to the SOs acceptance, to
supervise the field works. The excavation and earthworks shall be such that the design or required
lines, levels and grades meet the requirements of the Works and any surplus excavated material
shall be removed off the Site or as directed by the SO. The exposed faces of the excavation and all
slope shall be adequately protected with approved materials and measures in timely sequence in
accordance with the agreed method of construction.
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1.4.13
Registered Surveyor
Employ a Registered Surveyor who shall be responsible for surveying the site and submit the results to
the SO.
1.4.14
Quality Control Plan
Submit and work to a quality control plan as agreed with the SO. Refer to G01-010: Clause:1.4.7.
1.4.15
Safety
Provide safety precautions to comply with all current legislation and regulations, notably:
(a)
Building Control Act and Regulations
(b)
Code of Practice for Traffic Control at Work Zone
(c)
Workplace Safety and Health Act and Regulations
(d)
SS CP 79 Safety management system for construction worksites
(e)
For works within LTA Railway Protection Zone, ensure the works comply fully with Code of Practice for
Railway Protection.
Additionally, comply also with the following:
(f)
BRE Digest 251 (1995) Assessment of damage in low rise building
(g)
Not In Use
S(g)
BS 8008: Guide to safety precautions and procedures for the construction and descent of
machine-bored shaft for piling and other purposes.
1.4.16
(h)
Factories (Building Operations and Works of Engineering Construction) Regulations
(i)
Factories Act
Environmental Protection
Provide environmental protection measures and pollution control precautions to comply with all current
legislation and regulations.
1.5
Definitions and Abbreviations
1.5.1
Definitions
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1.5.1.1
Accredited Testing Laboratory
The Testing Laboratory shall mean an organisation or laboratory accredited under the
Singapore Laboratory Accreditation Scheme (SINGLAS) and fully equipped to carry out all tests
and checks required by the Specification.
1.5.1.2
formation
The surface of the ground after completion of any excavation or filling.
1.5.1.3
obstructions
Include rock, concrete, reinforced concrete, solid brickwork, sheet piles and the like, met within the
excavations, but excluding those met on the surface of the ground.
1.5.1.4
S1.5.1.4
Not In Use
rock
Material with a large coherent mass of such size and strength, which can be loosened or fractured only
by blasting, or the employment of heavy pneumatic tools, or by chemical expansion methods.
Loose boulders up to 1m³ in volume that can be removed are not classified as rock.
1.5.1.5
suitable material
All that which is acceptable in accordance with the Contract for use in the works and which is capable
of being compacted in the manner as specified to form a durable and stable fill, having side slopes as
indicated on the drawings and meeting all other necessary performance requirements.
1.5.1.6
non-suitable material
Other than suitable material, including:
(a)
Material from swamps, marshes or bogs
(b)
Peat, logs, stumps or other organic matter and perishable and toxic materials
(c)
Material susceptible to spontaneous combustion
(d)
Marine clay generally and clay of liquid limit exceeding 70 and/or plasticity index exceeding 35
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1.5.1.7
temporary works
All construction works that are not part of the permanent works but are required for their completion.
1.5.1.8
topsoil
Soil which by its nutrient content is capable of supporting the growth of vegetation.
1.5.2
Abbreviations
No item.
Note: Refer to EN 16907 on other definitions and abbreviations as applicable for the Works.
2
PERFORMANCE REQUIREMENTS
2.1
General
Carry out the earthworks in accordance with SS EN 1997-1 and SS EN 1997-2, and EN
16907-1 to EN 16907-6.
2.2
Site Clearing
The whole Site shall be cleared to the extent as shown in the relevant drawings. Include clearing,
grubbing and removing all trees, shrubs, vegetation and butts; and demolishing, breaking up and
removing all structures above ground level, such as buildings, walls, fences and other obstruction
within the Site which have been designated to be demolished or removed. All spoil and debris shall be
removed and disposed as approved or as directed by the SO.
Grubbing shall consist of the removal and disposal of surface vegetation, the bases of stumps, roots, the
underground parts of structures, and other obstructions to a depth of at least 0.5 m below ground level,
all with the agreement of the SO.
Stripping topsoil shall consist of the removal of topsoil to an average depth of at least 150 mm below
ground level, and its stockpiling for use in the Works, and/or its disposal, as directed by the SO.
Dump all materials resulted from site clearing to the approved dump site, unless otherwise directed by
the SO. Method statement on dumping with particular emphasis on prevention of environmental pollution
shall be submitted for the SOs acceptance.
2.3
Preservation of Existing Trees
Take precaution to protect from damage all existing trees and shrubs which are designated to be
preserved by NParks or as specified or directed by the SO. When necessary, adequate temporary
fencing shall be erected for each tree or a group of trees. When required, the tree shall be protected
by wrapping with suitable paling materials up to 1.5 m high.
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2.4
Demolition of Existing Structures
Any existing structures and other obstruction which are designated to be removed shall be demolished,
broken up, removed and disposed as approved by the SO.
All salvaged materials arising from the demolition work shall, unless otherwise specified, be removed
from Site as soon as possible.
Refer to the drawings or as specified or required by the SO on major structures which cannot practicably
be cleared by bulldozer and/or hydraulic excavator; whose demolition requires pneumatic tools,
explosives and/or other specialised equipment, and depth to which extent each of such structure
shall be demolished.
2.5
Temporary Earth Retaining Supports
The design for the temporary supports in C02-020:Clause:1.4.1.1 shall take into account of all loads and
actions as in SS EN 1997, including those due to the hydrostatic pressure, earth pressure, surcharge
loads, overburden, effects of surrounding properties and varying load conditions or unfavourable
conditions due to different stages of constructions.
The design of temporary earth-retaining supports and related works shall be in accordance to the
requirements of the relevant authorities and SS EN 1997, including the use of appropriate factors
and performance criteria in terms of performance requirements with regard to permissible earthretaining wall deflection and ground movement limits, as stipulated by taking into account the effects of
the designed temporary strutting or anchoring system and installation.
Verify the design based on SS EN 1997-1 and SS EN 1997-2, unless otherwise agreed by the SO.
2.5.1
Pits and Trenches
Design, supply, fix and remove all planking and strutting for the excavation as required. Take all
necessary measures to ensure that the sides of pits and trenches remain stable at all times against all
anticipated loadings; and to ensure the safety of the workmen and prevent damage to any adjoining
property. The design and execution shall comply with the requirements of SS EN 1997-1 and SS EN
1997-2.
2.6
Slope Stability
Provide necessary protective measures to ensure the durability and stability of slopes for the whole
duration of the slope’s design life.
Check slopes from both cut and fill against slip failure in accordance with SS EN 1997-1.
For slopes with intermediate berms, check the stability of both the overall slope and slopes between
berms.
For slopes formed in weathered or fresh rock such that joints dip into the excavation are exposed, the
potential for kinematic failure, including wedge, planar and topple failure shall be assessed, and
appropriate remedial measures shall be installed where necessary.
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2.7
Filling Works for Embankment
Design and execute the filling works to remain stable at all times.
Embankment construction over weak ground shall be staged to allow any required consolidation of
the foundation strata between stages and ensure stability of the foundation. For all such cases, before
proceeding to higher fill at every stage of filling works, the relevant parameters including strength and
porewater of the underlying soils shall be verified and reported to the SO for approval to proceed
further.
2.8
Ground Movements and Vibrations
2.8.1
Ground Movement and Vibration Control for Existing Critical Structures or Services
Unless values are already stipulated in the Contract, propose for the SOs acceptance, the permissible
ground movement and vibration limits due to the works taking into account the vulnerability and sensitivity
of the adjacent properties after carrying out damage impact assessment as stated in Section C02020:Clause:1.4.1.2.
State the limiting values for "alert" and "work suspension" levels as appropriate in the
submission proposal in accordance with the requirements of Building Control Act and
Regulations.
[Note 1: Refer to BCA advisory notes and guidelines on excavation and impact on neighbouring
properties.]
Notwithstanding the above, ensure that the values of ground movements and vibrations generated by
the Works shall not exceed the following requirements:
2.8.2
(a)
Generally comply with the requirements of BS 5228.
(b)
The vibration generated by the works in MRT structures shall not exceed a peak particle velocity of 15
mm/s.
(c)
Unless otherwise directed, refer to Section C02-050:Clause:4.2.2 for general restrictions on ground
movements and vibration limits for adjacent structures where relevant.
Consolidation Settlement
Upon completion of the Works, ensure that consolidation settlement due to filling activities have
achieved a degree as stipulated in the drawings or directed by the SO. Make good any settlement
that occurs up to the end of the period of maintenance.
Upon completion of the Works, ensure that consolidation settlement due to filling activities have
achieved a degree of 95% minimum, unless otherwise directed by the SO.
3
MATERIALS
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3.1
General
All materials excavated from the Site or imported into site for use as fill shall be classified as defined
below in this Section unless otherwise defined by the SO or shown in the drawings.
3.2
Unsuitable Fill
Unsuitable fill shall include but not be limited to:
3.3
(a)
cohesive soils having a liquid limit in excess of 80% or plasticity index in excess of 55%
(b)
any material containing topsoil, wood, peat or waterlogged substances
(c)
any material containing bio-degradable or organic material (more than 2.5%)
(d)
any material containing scrap metal
(e)
material from contaminated sites
(f)
material which by virtue of its particle size or shape cannot be properly and effectively compacted (e.g.,
some slate wastes)
(g)
material susceptible to significant volume change (e.g. marine mud, swelling clays and collapsible soils)
Classification of Materials for Compaction
For the purpose of compaction defined by Section C02-020:Clause:3.7.2, materials are grouped
as follows:
3.3.1
Cohesive Soil
Cohesive soil includes clays and silts with at least 15% passing the 63 m BS sieve and up to 20% of
gravel.
It shall have a moisture content not less than the value of the plastic limit (determined in accordance with
SS EN 1997-2) minus 4.
3.3.2
Well-Graded Granular and Dry Cohesive Soils
Well-graded granular and dry cohesive soils include clays and silts containing more than 20% of
gravel and/or having a moisture content less than the value of the plastic limit (determined in
accordance with SS EN 1997-2:2010) minus 4, and well-graded sands and gravel with a
uniformity coefficient exceeding 10.
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3.3.3
Uniformly-Graded Material
Uniformly-graded material includes sand and gravel with a uniformity coefficient of 10 or less, and silts
and pulverised fuel ashes.
[Note 1: Any soil containing 80% or more material in the particle size range from 0.06 mm to
0.002 mm will be regarded as silt for this purpose.]
3.4
Granular Fill Materials
In general, granular fill materials shall conform to the requirements of types 1 and 2 materials as
delineated below:
3.4.1
Type 1
Fill materials of this category shall consist of any combination of the following:
3.4.2
(a)
Crushed rock (other than argillaceous rock)
(b)
Crushed concrete
(c)
Crushed (non-expansive) slag
(d)
Well-burned non-plastic colliery shale
(e)
Natural sand
Type 2
Fill materials of this category shall consist of any combination of the following:
(a)
Crushed rock (other than argillaceous rock)
(b)
Crushed concrete
(c)
Crushed (non-expansive) slag
(d)
Well-burned non-plastic colliery shale
(e)
Natural sand
(f)
Natural gravel
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3.4.3
Gradation
The particle size distribution, determined in accordance with SS EN 1997-2, EN 14688-2 and EN
ISO 17892-3, shall be within the grading limits below:
Table 1. Gradation of Granular Fill Materials
% by mass passing
BS Sieve Size
3.4.4
Type 1
Type 2
75 mm
100
100
37.5 mm
85 - 100
85 - 100
20 mm
60 - 100
60 - 100
10 mm
40 - 70
40 - 100
5 mm
25 - 45
25 - 85
600 micron
8 - 22
8 - 45
63 micron
0 - 10
0 - 10
Plasticity of Fines
The material passing the 425 micron BS sieve, when tested in accordance with SS EN 1997-2, shall
be non-plastic for type 1 granular material and shall have a plasticity index of less than 6% for type 2
granular material. Report for each test, the amount of material retained on the sieve.
[Note 1: These requirements may be a bit restrictive for general granular fill. Typically, if less than
15% fines (<63 microns), it is then acceptable even if slightly plastic. These requirements are more
onerous than that for Special Fill as described below Section C02-020:Clause:3.2.]
3.4.5
Crushing Resistance
In a test to determine the crushing resistance in kN required to produce "ten percent fines value" or
10% of fines by mass of the test sample, the fill materials shall have the following minimum crushing
resistance:
Table 2. Fill materials and minimum crushing resistance
Material
Load (kN)to produce 10% fines
Type 1
50
Type 2
50
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3.5
Special Fill Material
When required in the project, special fill material may consist of suitable material of which at least
95% shall pass a 125 mm BS sieve and at least 90% shall pass the 75 mm BS sieve. Up to 5% of
the material may be made up from isolated boulders of maximum dimensions not exceeding half the
thickness of the layer of material being placed, provided that the fill can be compacted in the manner
as specified in C02-020:Clause:4.7.
The coefficient of uniformity shall be greater than 10. The fraction passing a 63 m BS sieve shall be
less than 20% by weight and shall have the following characteristics:
3.6
(a)
Liquid limit not exceeding 35
(b)
Plasticity index not exceeding 12
Rock Material
Provide clean well-graded quarry waste from sources outside the Site. The material shall be
resistant to weathering. The maximum size particles in the material shall pass through a rigid 200
mm square grid and the largest dimension of any particle shall not exceed 300 mm. The material
shall not have more than 10% of its particles passing a 0.63 mm BS sieve.
Rock used in rock fill embankments shall, except for any specified external cover to slopes or within 500
mm of formation levels, be of such size that it can be deposited in horizontal layers each not exceeding
450 mm loose depth and extending over the full available width of the embankment.
3.7
Hardcore
Hardcore shall consist of any combination of the above, together with broken brick free from plaster,
dust, loam, wood, rubbish or organic materials. All pieces shall be less than 75 mm in any direction.
3.7.1
Crushing Resistance
The hardcore material shall have a crushing resistance of not less than 50 kN for 10% fines value.
Refer to C02-020:Clause:3.1.5.
3.8
Fill Materials from Excavated Rocks
Propose for the SOs acceptance on the use of excavated rocks of satisfactory quality that shall be
crushed and screened to produce aggregates required for concrete, road base, subbase, or other
purposes with the prior approval of the SO.
Propose for the SOs acceptance on the replacement of excavated rock needed for earthwork
construction with borrowed materials of satisfactory quality from alternative locations approved by the
SO.
Unless otherwise agreed by the SO, excavated rock shall be used in the construction of
embankment, and fill as approved or directed by the SO, to the fullest practical extent, in one of the
following ways:
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3.9
(a)
Excavated rock shall be broken down to a maximum particle size of 300 mm and used as rock fill.
(b)
Excavated rock shall be broken down to a maximum particle size of 150 mm, blended with suitable earth
fill material in a proportion not exceeding 1 rock to 1 earth, and used as common fill.
Materials with Excessive Moisture Content
Naturally occurring materials within the Site that are non-suitable due only to excessive moisture
content may be spread and dried or may be blended with other suitable materials. The use of
material treated in this way shall be subject to the acceptance of the SO.
3.10
Blinding to Fill
Blinding layer to the surfaces receiving sheet overlays or concrete shall be either of the following:
(a)
Grade 15 concrete
(b)
Sufficient sand, fine gravel or other approved fine material applied to fill interstices and moistened as
necessary before final rolling to provide a flat, close smooth surface
Sand for blinding shall meet the requirements of SS 31, Table 6, Type C or M.
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3.11
Geotextile Sheet
Unless otherwise specified, geotextiles shall be non-woven and shall be made of polypropylene,
polyethylene, polyester or a combination of the aforesaid materials.
Geotextiles shall not be susceptible to bacterial and fungal attack and shall be resistant to chemical
action and not affected by exposure to ultra-violet light.
Use Class A geotextiles where the geotextiles serve as a separation or reinforcement function, Use
Class B geotextiles where the geotextiles serve as a filtration function. The property requirements for
Class A and Class B geotextiles are specified below.
Submit methods of laying and jointing prior to commencement of work.
Table 3. Physical properties of geotexiles
Class of Geotextile
Physical Property
Specification
Class A
Class B
Minimum
Unit Weight, g/m2
125
50
ASTM D5261 or
ISO 9864
Minimum Grab
Tensile Strength, N
530
270
ASTM D4632
Minimum Elongation
To Break, %
60
55
ASTM D4595
Or ISO 10319
Minimum Trapezoidal
Tear Strength, N
180
80
ASTM D4533
Water Permeability,cm/sec
2.0x10 -2
2.7x10 -2
Manufacturer’s
test report to be submitted
4
WORKMANSHIP
4.1
Preparatory Work
4.1.1
General
Carry out at least the following in preparing the Site for excavation or fill. All materials resulting from site
clearing shall be dumped at the approved Contractor’s dump site, unless otherwise directed by the
SO. The method statement on dumping with particular emphasis on prevention of environmental
pollution shall be submitted for the SOs agreement.
Confirm the extent of work before proceeding:
(a)
Break out old foundations, beds, drains, etc. Seal off drain ends and remove contaminated earth. Backfill
as necessary.
(b)
Remove existing fences, gates, walls, roads, paved areas and other site features as required.
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(c)
Remove trees, shrubs and hedges as shown on the drawings. Cut down, grub up main roots and fill voids.
Dispose of all wood using methods approved by the relevant authorities.
(d)
Clear site of rubbish and vegetation. Grub up and dispose of large roots.
(e)
Remove unwanted materials from Site.
[Note 1: The work involving removal or planting of trees shall be carried out in accordance with the
requirements of National Parks Board, Singapore (NParks). Where there are extensive site
features/trees to be removed, mark the relevant items on site.
Co-ordinate this requirement with clauses of the contract preliminaries and/or other sections such as
demolition sections, C01-010, covering the protection of features to be retained.]
4.1.2
Ground Movements
Verify the precise topography and layout of the site, with all key features and neighbouring structures
accurately surveyed, as per the requirements stated in G02-020:Clause:1.4, and establish an agreed
datum to monitor ground movements at the start of the Works.
4.1.3
Demolition of Existing Structures
Any existing structures and other obstructions which are designated to be removed shall be demolished,
broken up, removed and disposed as approved by the SO.
4.1.4
Topsoil
Remove all topsoil to full depth (including turf) from the areas of cuttings and embankments, and
other areas shown on the drawings. Remove topsoil also from existing embankments required to
receive additional fill and from areas of new ditches and watercourses. Stripping topsoil shall consist
of the removal of topsoil to an average depth of at least 150 mm below ground level, and its
stockpiling for use in the Works, and/or its disposal, as directed by the SO.
Stockpile all removed top soil for reuse, where practicable. Remove
the topsoil in accordance with BS 3882.
4.1.5
Areas for Stockpiling
Make arrangements and provide appropriate areas for stockpiling of topsoil and/or suitable material.
Topsoil to be stockpiled for the Works shall be sufficiently fertile to promote and support the growth of
vegetation, and shall be taken from such areas where clearing, grubbing and stripping of topsoil is
required as approved or directed by the SO. Before stockpiling, separate topsoil from objectionable
materials, all to the agreement of the SO and in accordance with BS 3882. Arrange for stockpile sites
either within or outside the project site as agreed by the SO.
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4.1.6
Disposal of Material
Objectionable material from clearing, grubbing and stripping topsoil (including the demolition of structures)
shall be disposed of as approved or directed by the SO.
Subject to the SOs agreement, pile up combustible material, including all timber (except timber to
be salvaged or used), all brush, stumps, roots, vegetation and other combustible refuse within the
Site as agreed or directed by the SO, and burned, where burning is allowed or as agreed or directed
by the SO.
All burning shall be subject to the prior approval of the relevant statutory authorities, and shall be
carried out in conformance with all pertinent regulations. Burning shall also be carried out at such
places and at such time and in such a manner as to prevent fire from damaging vegetation and
property within the project site designated to be preserved, and from spreading to areas adjoining the
project site and damaging vegetation and property therein.
Where burning is not permitted at any time, or if objectionable material is not to be burnt, combustible
material shall be disposed of, together with incombustible material.
All necessary provisions shall be made for incombustible material, including where appropriate, the
remains of burning, to be disposed of in a safe and tidy manner at solid waste dumps outside the
Site, whether on public or private land, unless otherwise approved or directed by the SO.
4.1.7
Ground improvement by Jet Grouting Method
Carry out ground improvement if necessary prior to commencing the earthworks. For jet
grouting methods of ground improvement, refer to Section C02-040-1.
4.1.8
Verification of Ground
Verify the ground conditions detailed in any available ground investigation report, and evaluate and
develop a specific ground investigation report for the project in accordance with SS EN 1997-1 and
SS EN 1997-2. Keep a copy of the latter ground investigation on site for verification and update of
the ground conditions.
Continue to add to the ground investigation report throughout the full duration of the Works, including
not only preconstruction ground investigation data, but all monitoring data, and test data from both the
natural ground and the fill and embankment material.
[Note 1: The ground investigation report in accordance with SS EN 1997-1 and SS EN 1997-2 does
not necessarily take the form of a single report, but can be a collection of reports and relevant
geotechnical data.]
4.2
Excavation: General Requirements
4.2.1
Drainage of Excavations
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4.2.1.1
General
Arrange for the rapid dispersal of water shed on to the Site from any source. Where practicable, and
in accordance with authority’s requirements, discharge the water into the permanent outfall for the
drainage system. Provide adequate means for trapping silt on temporary systems discharging into
permanent drainage systems.
4.2.1.2
S4.2.1.2
Not In Use
Provision of Temporary Systems
Provide where necessary temporary water courses, ditches, drains, pumping or other means of
maintaining the earthworks free from water. Maintain a sufficient minimum surface crossfall at all
times and, where practicable, a sufficient longitudinal gradient to enable them to shed water and
prevent ponding.
[Note 1: Typically, minimum surface crossfall is 4%.
Note 2: It may be practically impossible to keep open excavations totally dry – the intention of this
Clause is for any water which does enter to be rapidly removed. Refer to EN 16907 and BS 6031 for
additional guidance.
Note 3: Particular care is necessary when excavating close to water mains or on sloping ground.]
4.2.1.3
Temporary Obstruction of Free Drainage
Do not rely on pumping to provide drainage where temporary earth dumping obstructs the free drainage
of a cutting.
Construct temporary drains to a suitable outfall or install a permanent drainage through the dumping to
ensure free drainage for the whole duration of the Works.
4.2.2
Surface and Percolating Water
Provide for adequate measures so that the stability of the excavation and nearby ground are not
undermined by surface and percolating water through the process of ground loss, consolidation
and/or increase in lateral earth loading and to maintain the stability of the excavation. These
measures shall at least include the following:
(a)
Carrying out adequate slope protection.
(b)
Diverting surface and percolating water clear of all excavations by means of temporary drains and sumps,
and provide a groundwater recharging system, etc., if necessary.
(c)
Filling up and sealing on a daily basis all movement cracks that appear on the surface of adjacent ground
and continue until ground movement has ceased.
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Any bank slips, erosion of slopes and other forms of ground loss, and any consequential damage
to drains, culverts, pipes, utilities, etc. occurring in the course of excavation and during the period
when the excavation stays open, shall be rectified and made good.
4.2.3
Dewatering
4.2.3.1
General
Give particular attention to avoid soil consolidation and ground loss next to the excavation caused by
fluctuations in the water table level. In the event that temporarily pumping water out from excavations
may lower down the water tables, take due care in protecting the stability of all structures and prevent
any non-allowable settlement from occurring on these structures.
Groundwater control and drawdown shall comply with the requirements of SS EN 1997 and be in
accordance with the methods agreed with the SO.
The dewatering method chosen shall ensure the stability of the excavation and the safety of nearby
structures.
Assess the effects of dewatering settlement on structures, services and land in the vicinity, in accordance
with SS EN 1997-1 and with the acceptance of the SO.
[Note 1: Techniques such as sheet piling or the injection of cement grout or bentonite clay slurry or in
combination, may be necessary in some deep excavations below the ground water table.]
4.2.3.2
Damage Due to Settlement
Where settlement due to consolidation is predicted to cause unacceptable damage to structures
or utilities, implement measures to prevent such damage.
Provide a risk register which details appropriate mitigation measures to ensure settlement does not
exceed the predicted values, but also plan for appropriate remedial measures in the event that
settlement exceeds predicted values.
4.2.3.3
Drainage Control Measures
For excavations carried out in permeable material below groundwater level, make provisions for
adequate drainage control measures to prevent piping or a general weakening of the foundations
due to the flow of water.
4.2.4
Adjacent Excavations
Where excavations are to be made in close proximity to each other, agree with the SO to complete the
deepest excavations first and, where required, fill.
Do not place excavated material adjacent to the excavation, unless the additional surcharge from
such placement has been considered in the design.
[Note 1: Specific ground and site conditions need to be assessed in order to determine any particular
requirements to the Works.]
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4.2.5
Surplus Excavated Material
Remove all surplus materials that are not specified to be spread and levelled on site and dispose of
to a suitable location. All materials resulting from site clearing shall be dumped to the approved dump
site, unless otherwise directed by the SO. Method statement on dumping with particular emphasis on
prevention of environmental pollution shall be submitted for his agreement.
4.2.6
Formations
(a)
Remove the last 150 mm of excavations above formation level just before inspection. Trim excavations to
the required profiles and levels, and remove all loose materials.
(b)
Keep the bottom of all excavations free from mud and water, trim clean, protect from the effects of weather
and thoroughly compact and consolidate by approved means.
(c)
Unless otherwise specified, seal formations within 4 hours of inspection with concrete or other agreed
blinding.
[Note 1: Depending how long the cut surface is left exposed before exposing the top of the
formation for development, a thicker protective layer of 150 mm to 300 mm may be
appropriate.]
4.2.7
Surcharge Adjacent to Excavation
Surcharge loads or actions due to construction or other vehicles and equipment, excavated material,
or other stockpiled material shall not be placed alongside the banks of the excavation without first
making adequate provisions to underpin such loads and ensuring the stability of the excavation at all
times.
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4.2.8
Protection of Slopes and Banks
All exposed earth slopes shall be protected with approved temporary protection immediately without delay
after they are cut or formed prior to the application of permanent protection, i.e. closed turfing or
hydroseeding and before proceeding further.
Temporary protection shall not be removed until proper and adequate slope drainage (berm drains,
cascade drains and toe drains) and permanent protection (close turfing or hydroseeding) are
constructed in accordance to the drawings or as approved by SO.
As earthworks progress, slope shall be protected and maintained in a diligent and expeditious manner on
completion of each stage of excavation.
Any deviation from the agreed method or sequence of slope protection must be approved in advance by
the SO prior to implementation.
The slopes of cuttings shall be cleared of all rock fragments which move when prised with a crowbar. Where, in the slopes of cuttings, layers of rock and soft material alternate, agree with the SO on
the protective measures for the slope, immediately after dressing, that can be affected by weather,
and the replacement of any insecure material to an approved depth and build up the resulting
spaces, including the use of grade 15P / 20 concrete, shotcrete, or masonry using rock similar to the
adjoining natural rock so as to ensure a stable face. Any such protective measure, materials and
method shall be subject to the agreement of the SO.
4.2.9
Dimensional Tolerances
Slopes in cutting shall be trimmed mechanically to neat and even surfaces which shall have gradients
not steeper than that shown on the drawings. Widths of excavations shall not exceed the dimensions
shown on the drawings by more than 300 mm and shall be obstruction free to complete the Works,
unless otherwise approved by the SO.
4.2.10
Trafficking in Cuttings
Do not permit constructional traffic other than that required for the excavation and trimming, on the
surface of the bottom of a cutting unless the cutting is in rock or as agreed or directed by the SO.
Make good any damage to the sub-grade arising from such traffic on the surface with same materials or
materials having the same characteristics.
4.2.11
Separation of Materials
Where the excavation reveals a combination of Suitable and Not Suitable Materials, carry out the
excavation in such a manner that Suitable Materials are excavated separately for use in the works
without contamination by Not Suitable Materials.
[Note 1: It may be feasible to treat Not Suitable Materials by either blending with Suitable Materials or
by the addition of additional additives but where possible this should be undertaken only after the
materials have been excavated and separated.]
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4.2.12
Temporary supports
Provide temporary supports, including temporary retaining structures, strutting and ground anchors where
necessary, in accordance with SS EN 1997-1 and the accepted design proposals.
Ensure that the construction sequence comply with the accepted design proposals. Obtain the approval
from the SO and the PE for temporary supports for every level of support before proceeding with
further excavations to the next level of support.
The method of construction of temporary works shall take into account the following:
(a)
The geology along the length and depth of the cutting
(e)
The water levels, hydrogeology and strata permeability along the length and depth
(f)
The expected movements or settlements and the anticipated effect on neighbouring structures
(g)
The depth of construction required
(h)
Any particular difficulties that special plant might meet with respect to access, clearances and working
space
(i)
Control of heave and instability of the base of excavation
(j)
The adequate support of existing utilities affected by excavation
(k)
The operation of heavy equipment, storage of bulk materials and any other form of surcharge next to
excavation
(l)
Control of lateral load increase and ground loss induced by water seepage through ground surface cracks
behind temporary retaining structures
4.3
Excavations: Pits and Trenches
4.3.1
General
Ensure the sides of pits and trenches remain stable at all times.
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4.3.2
Supports to Excavation
Where required by the nature of the materials being excavated, provide all necessary planking, strutting,
shoring, ground anchoring and any necessary staging for upholding the face of the excavation.
Before removing any planking, ground anchors or struts, demonstrate that there is sufficient support to
the retained ground to avoid excessive movement.
For temporary ground anchors, as soon as progress of the Works permits and with the acceptance of
the SO, de-stress temporary ties and remove all strands if required. Identify locations where ties are to
remain and ensure these are accepted.
Alternatively, subject to the prior agreement, suitably batter the face of the excavation.
4.3.3
Struts and Walings
Struts and wailings shall be adequate to sustain the calculated maximum loads without failure or
unacceptable deflections.
When necessary, preload struts to remove any slackness of the propping system. Submit the proposed
magnitude of preloading for the SOs acceptance.
Ensure the gaps between the waler and the retaining wall are properly wedged or packed to SOs
acceptance.
Indicate all working loads of struts clearly on the relevant construction drawings. Design of
struts and walings shall comply with SS EN 1997, SS EN 1992, SS EN 1993. Refer to
Technical Reference TR26, BS 8002 and CIRIA C760.
4.3.4
Timbered Excavation
Submit for the SOs acceptance the use of timbered members for proper support to the sides of
excavation as appropriate.
Propose for the SOs acceptance the use of additional suitable methods as ground water cut- off
system such as jet grouted piles in adverse ground conditions, including water-bearing granular soil
conditions where water leakage into the excavation will cause significant groundwater drawdown
leading to ground loss and/or soil consolidation resulting in adverse impact on the surroundings.,
All timber elements shall be removed on completion of work, but where timber is likely to be left in
place, use treated timber to prevent rotting.
4.3.5
Width and Length of Pits and Trenches
Trenches and pits shall not be wider than is necessary for the efficient laying and jointing of pipes or for
other works to be carried out. Do not excavate more than the agreed length of trench at any one
time.
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4.3.6
Base of Excavation
Ensure the bottom of all excavations is to the correct levels as required. The base of all excavations,
after being trimmed and levelled, shall be well rammed and compacted to form a solid formation to the
approval or as directed by the SO. The prepared formation shall be protected and prevented against
damage or adverse effects from weathering, trampling by personnel and other construction activities.
Fill any over-excavation of foundation pits or trenches below the specified levels with Grade 15 concrete
to the specified levels.
In a situation where concrete is placed without first having prior approval of the SO or verification by
testing or otherwise to SOs acceptance that the base of any excavation is at least of the required
bearing capacity and/or having the minimum modulus of subgrade reaction, the concrete that has
been placed shall be removed to allow excavation to continue deeper.
Remove any pockets of soft material or loose rock at the bottom of pits and trenches and fill the
resulting cavities and any large fissures with Grade 15 concrete, or otherwise fill with Suitable
Material compacted in layers as required. Do not trim the side faces within 24 hours after placing
such concrete.
In situations where the excavation has gone beyond or below the designated lines or levels of competent
stratum, or where the prepared formation has deteriorated and become soft or unstable or not in
accordance to the Drawings or specifications, such over-excavation and softened formation shall be
replaced with approved granular fill or as directed by the SO.
4.3.7
Spoil
Remove all surplus spoil immediately on excavation and keep reusable material tidy at all times.
4.3.8
Handling and Disposal of Excavated Materials
Provide for excavation works and disposal of excavated materials to include any additional handling, the
temporary formation of spoil heaps and re-excavating from within the Site and raising to higher levels as
required or directed by the SO.
No excavated material shall be removed from the Site except on the direction or with the approval of
the SO. Depending on the construction methods and operational activities where suitable materials
are permitted to be removed from the Site, any consequent deficit of fill material arising the reexcavating from shall be made good. Unless designated dump sites have been shown in the
drawings, dispose surplus suitable material at the approved dump areas outside the Site as
approved by the SO and in compliance with statutory requirements such as payment of royalties,
environmental protection, etc. Take all precautions and preventive measures to avoid any spillage or
soiling of the public roads during the earth removal operation. A method statement on dumping with
particular emphasis on prevention of environmental pollution shall be submitted to the SO for
agreement prior to dumping.
4.3.9
Not In Use
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S4.3.9
Backfilling of Pits and Trenches
Use Suitable Material, deposited and compacted by approved plant in accordance with Section 02020:Clause:4.7.2 or otherwise, as agreed with the SO.
Remove timber sheeting and other excavation supports carefully as the filling proceeds except where
they are required to be left in the position as agreed.
4.4
Excavations: Cuttings and Slopes
4.4.1
Excavation in Rock
Unless otherwise specified, excavation in rock shall extend to at least 150 mm below the specified
formation level and backfilled with approved materials.
4.4.2
Undulation
In all cuttings, whether in earth or rock, undulation in the general plane of the slope shall not be
permitted.
4.4.3
Loose Material
Remove any overhanging, loose or unstable material on slopes.
4.4.4
Drainage
Ensure the working areas are adequately drained throughout the period of construction.
The excavation shall at all times be kept well drained and dry by means of temporary slopes, drains,
sumps, etc., and by pumping. As earthworks progresses, temporary concrete drainage channels with
cascades shall be provided and maintained for the efficient drainage of the area. These drains shall be
cut to a gradient not exceeding 1 in 100. Temporary drains after use shall be demolished, removed
and make good as required or directed by the SO. Subject to the SOs approval, provide and install a
drainage and sump system at the final excavation level, and maintain the drainage and sump
system for the duration the excavation is kept open.
All temporary drains shall be directed to the nearest water course or to sumps which are pumped
out to the roadside drain. The roadside drain shall have an adequately large section so that no mud
or water spills onto the roads or pavements. Only self-priming submersible pumps of sufficient
capacity such as Flygt pumps or similar equipment shall be used. Pumps shall be of sufficient number
and capacity to provide adequate pumping capability in the event of breakdown.
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4.4.5
Benching
Unless otherwise specified, when cutting through any material subject to fretting, provide a 900 mm
wide horizontal bench at a height of 600 mm above the table drain. Slope the cut surface at both
ends of the bench in accordance with Section C02-020:Clause:4.4.6.
In cutting earth overlaying rock, which is required to be cut to a slope steeper than 1:2, provide a 900
mm wide horizontal bench at the interface and slope the rock and earth surfaces in accordance
with Section C02-020:Clause:4.4.6.
4.4.6
Required Slopes
Cut slopes shall satisfy the requirements for stability as provided in Section C02- 020:Clause:2.6.
4.5
Excavation: Rock Blasting
4.5.1
General
In a situation where rock is encountered in the course of excavation, remove it by approved means,
which may include blasting.
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4.5.2
Rock
Rock refers to those geological strata of hard materials which necessitate the use of blasting or approved
pneumatic tools for their removal. Rock excavation shall be carried out by methods appropriate to Site
requirements as approved by the SO.
Agree with the SO on the type of equipment or machinery or process, including size of the in- situ
material, for the removal of material that is classified as rock and boulder.
[Note 1: For determining the volume of individual boulders, the average diameter of the boulder in 3
orthogonal directions can be taken and used to calculate the volume of the boulder. In local practice,
individual masses of rock less than 0.5 m3 are usually considered as boulders that may be
mechanically excavated and will not need blasting or other methods, machinery or equipment
required to remove rock.
Note 2: In local practice, rock does not include material which can be loosened by using a dozer
mounted drawn ripper of the following description with a production rate not exceeding 50 m3/hr:
Tractor Unit: Equipment with a minimum weight of 37 tons and a net horse power rating of 305 brake
horse power or more. The tractor unit shall be in good condition and operated by experienced
personnel skilled in the use of ripping equipment.
Dozer Unit: Plant with a minimum weight of 236 kN and net horsepower rating of 300 h.p. or 225
kw. The tractor unit shall be in good condition and operated by experienced personnel skilled in
the operation of ripping equipment.
Ripper Unit: The ripper to be attached to the abovementioned tractor should have a minimum
penetration force of 120 kN. The ripper should have a single shank in good working condition with a
sharpened cutting point.
Note 3: Shale and clay boulders are not considered as rock.
Note 4: Rippable material is considered to comprise material that cannot be excavated using standard
digging methods (backhoe or face shovel) but can be ripped using one of the following:
- A bulldozer with a single shank ripper (up to and including the CAT D9 Ripper or similar) and minimum operating
mass of 35 tons.
- A hydraulic excavator up to and including those with a minimum net flywheel power of 200 kW (CAT 330D L or
similar) and with hydraulic breaker with a minimum of 1 700 kg service weight (Atlas Copco MB1700 or similar)].
4.5.3
Use of Explosives
On each occasion that the use of explosives is proposed:
(a)
Obtain the written consent of the SO.
(b)
Obtain all necessary licences and permits from the appropriate authorities and conform to all statutory
acts and regulations relating to transport, storage, handling and use of the explosives.
(c)
Conform to the rules and regulatory requirements of the Singapore Police Force - Arms and Explosives
(A&E) Police Licensing & Regulatory Department (PLRD)
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Check that the method of blasting is safe, and that all statutory and imposed limitations are adhered
to; and comply with the conditions of issue of the permit. Obtain all necessary licences for the
procurement, possession, transport, storage and handling of explosives and to ensure the validity of
such licences at all times. Before starting work, submit for the SOs acceptance that all the required
permits are in order and that this category of work is adequately covered in the insurance policies.
4.5.4
Storage and Handling for Explosives
Provide proper buildings or magazines in suitable positions for the storage of explosives in manner and
quantities to be approved; and ensure no unauthorised issue or improper use of any explosives
brought on the Works. Employ suitably experienced and qualified personnel to handle explosives for the
purpose of the Works. Comply with the relevant security regulations dealing with the storage, handling
and transport of explosives at all times.
4.5.5
Blasting Limits
The maximum permissible air overpressure must not exceed 110 dB. Blasting shall be restricted to
such periods as directed by the SO and as prescribed or required by the relevant authorities. In situation
where blasting is deemed to be dangerous to persons or property or to any finished work or is being
carried on in a reckless manner, the rock shall be excavated by other means, including chemical or
mechanical splitting, or hydraulic breaking as directed or required by the SO. The use of explosives in
large blasts, as in seams, drifts, shafts, pits or large holes, is prohibited unless authorised in writing
by the SO.
[Note 1: Using 9 kg or more of explosive is considered as large blast.]
All drilling and blasting shall be done in such manner as to bring the excavation as close as possible
to the required cross-section or profile and to disturb as little as possible the material to be left in place.
Make all provisions for any extra work occasioned by breakage outside the required cross-section or
profile when blasting by means of drill holes, tunnels or any other similar method is carried out.
4.5.6
Safety Precautions
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4.5.6.1
General
When blasting is proposed, determine the danger zone likely to be created and ensure that no damage is
caused to persons or property on or off site.
Provide full details as to the steps and precautionary measures to be taken to safeguard the surrounding
properties.
Inform the SO of the steps taken to safeguard the surrounding property and lives and to mitigate,
protect or prevent any damage or annoyance caused by reason of blasting.
Explosives shall be used in the quantities and manner recommended by the manufacturers and
blasting specialist.
Provide all necessary steps to preserve in the soundest possible condition the materials below and
beyond the lines of all excavations. Delayed blasting to reduce shock waves shall be used to avoid
damage to concrete and other works already completed. As the excavation approaches its final lines,
blasting with pre-splitting technique of approved drillhole spacing shall be carried out to reduce blast
damage and create reasonably even finished surface by means of parallel drill holes perpendicular to
the toe of the excavation and parallel to the finally required face.
4.5.6.2
Road Closures
When blasting operations are being carried out, close any road affected to traffic and erect the
appropriate signs in accordance with the latest "Code of Practice for Temporary Traffic Control"
published by the LTA and other authority requirements.
Prior to the start of blasting operations, conduct a survey of all structures and services within 120 m of
the site where blasting is proposed and any other structures within an area of influence or as
required or directed by the SO to establish the existing or pre-blast condition of these structures.
All blasting works shall be carried out within the hours as approved by the relevant authority and by
the SO.
4.5.7
Removal of Loose Material
Upon completion, all rock faces shall be scaled of loose blocks.
[Note 1: Rock blasting will not be required for most building work. Where this is considered, it is
essential to involve those experienced in such operations and to ensure full compliance with all
regulations and safety precautions.]
4.6
Filling: Generally
4.6.1
General
Filling works shall include the preparation, placing and compaction of Suitable Material at specified
areas.
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4.6.2
Placing Fill
The areas that are to be filled shall be free from loose soil, rubbish and standing water.
Take all necessary precautions to ensure stability of adjacent structures. Ensure plants employed for
transporting, laying and compacting are suited to the material.
Spread and level material in layers and compact as soon as practical. Lay differing materials separately
so that only one type of material occurs in each layer.
[Note 1: Filling needs to be well compacted so that structures, paving, drainage, etc. are not affected by
settlement. All compaction works shall comply with Section C02-020:Clause:4.7.
Refer to BS 6031 and EN 16907 for guidance on placement methods for even spreading.]
Where fill platform is to be constructed against existing ground with a cross-slope of steeper than 1
(vertical) to 10 (horizontal), the foundation shall be excavated in all materials (including hard rock) to
form benches with horizontal and vertical faces from which construction of the fill platform shall proceed.
The maximum vertical height of each bench shall not exceed 500 mm. The benches shall be
contiguous beneath the full width of the fill platform, and shall be of a suitable width to accommodate
construction equipment such as motor-graders, trucks, rollers, etc.
Unless otherwise agreed by the SO, the horizontal and vertical faces of the benches shall be
scarified, and the material excavated in forming the benches can be used as fill in the platform as
approved by the SO.
4.6.3
Stability of Works
Filling works shall remain stable at all times.
4.6.4
Weather Condition
Stop all filling works when the weather is judged by the SO as would adversely affect the compaction of
the fill.
4.6.5
End Tipping
End tipping of fill is not permitted unless otherwise agreed by the SO.
4.6.6
Soft Spots
Where any undue movements due to the presence of soft unstable soil under the fill occur, or
unsuitable material is encountered at the bottom of the fill, it shall be excavated to such depth and
over such areas as approved by the SO, and shall be removed to spoil. The resulting excavation
shall be backfilled with suitable material as specified in this Section or as directed by the SO, and
deposited in loose lifts not exceeding 225 mm thick and compacted as described above, or with
compaction equipment suitable for working in small excavation.
Provide in the execution to allow for settlement or displacement of fill over soft areas, and build up to the
required finished level with necessary compaction as appropriate.
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4.6.7
Filling Under Floors, Aprons, Beside Pilecaps and Trenches
Filling shall be provided and laid under floors, aprons, etc., where required or directed by the SO.
Filling shall be of suitable material as specified in this Section, deposited in loose lifts not exceeding
150 mm in loose thickness, and each loose lift shall be well watered where necessary, rammed and
compacted. No clay shall be used for filling under floors and aprons unless with the approval by the
SO.
Propose for the SOs acceptance free draining coarse grained materials to be used for backfilling in
areas where compaction is practically difficult due to space constraint.
4.7
Filling: Compaction of Fill
4.7.1
General
All materials shall be compacted in layers as soon as practicable after deposition.
Upon completion and before overlaying, the surface of the layer shall be free from ridges, cracks,
loose material, potholes, ruts or other defects. Rectify such defects to the full thickness of the layer
before overlaying.
Before commencing any filling, test each class of material to be compacted by an acceptable
laboratory to establish the maximum value of the dry density that can be achieved and the
optimum moisture content for compaction. Test in accordance with EN 13286-2. The number of tests
required for each source material shall be as indicated in the Bill of Quantities or drawings or as
required by the SO.
[Note 1: Generally it is advisable to conduct additional tests, including laboratory Californian Bearing
Ratio (CBR), and Moisture Condition Value (MCV) tests. Refer to EN 16907-2, Table 13 for an
indication on the types of tests recommended, depending on how the fill will be used.
Note 2: Requirements for compaction should only be relaxed for landscaping filling which does not
support any structures or paving, and for which settlement behind retaining structures will not be an
issue.]
4.7.2
Compaction by mechanical plants
Refer to Table 4 which gives requirements for establishing appropriate use of compaction methods and
mechanical plants.
The depth of each compacted layer shall not be greater than the maximum depth of the compacted layer
stipulated for each type of compaction plant.
Earthmoving plant shall not be accepted as compaction equipment.
Alternative methods or plants may be accepted which can be demonstrated to the satisfaction of the
SO at site trials that the required field density can be achieved.
Table 4. Requirements for the use of compaction plants
Cohesive Soil
Type of
Compaction
Well-graded granular
and dry cohesive soils
Uniformly -graded
materials
Category
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Plants
Max depth
of Compacted
layer (mm)
Min No.
of
passes
Max depth
of
Compacted
layer (mm)
Min No.
of
passes
Max depth
of
Compacted
layer (mm)
Min No.
of
passes
Smoothwheeled roller
Force per 100 mm
width
.
.
.
.
.
.
.
2.1 - 2.6 kN
2.61 - 5.2 kN
125
125
8
6
125
125
10
8
125
125
10*
8*
.
More than 5.2 kN
150
4
150
8
Unsuitable
Grid-roller
Force per 100 mm
width
.
.
.
.
.
.
.
2.6 - 5.2 kN
150
10
Unsuitable
150
10
.
5.3 - 7.8 kN
More than 7.8kN
150
150
8
4
125
150
12
12
Unsuitable
Unsuitable
Tamping roller
More than 40 kN
225
4
150
12
250
Pneumatictyred roller
Wheel Load
.
.
.
.
.
.
1 - 1.5 tonnes
125
6
Unsuitable
150
.
1.5 - 2 tonnes
150
5
Unsuitable
Unsuitable
2 - 2.5 tonnes
2.5 - 4 tonnes
4 - 6 tonnes
6 - 8 tonnes
8 - 12 tonnes
More than
12 tonnes
175
225
300
350
400
6
5
4
4
4
125
125
125
150
150
12
10
10
8
8
Unsuitable
Unsuitable
Unsuitable
Unsuitable
Unsuitable
450
4
175
6
Unsuitable
.
.
.
.
.
75
75
16
12
150
150
16
12
4
10*
Vibratory
Roller
Force per 100 mm
width
.
.
0.25 - 0.45 kN
0.46 - 0.70 kN
Unsuitable
Unsuitable
.
0.71 - 1.25 kN
1.26 - 1.75 kN
1.76 - 2.30 kN
2.31 - 2.80 kN
2.81 - 3.50 kN
3.51 - 4.20 kN
4.21 - 4.90 kN
100
125
150
175
200
225
250
12
8
4
4
4
4
4
125
150
150
175
200
225
250
12
8
4
4
4
4
4
150
200
225
250
275
300
300
6
10*
12*
10*
8*
8*
8*
Vibratingplate
Compactor
Static
pressure
under base plate
.
.
.
.
.
.
.
8.6 - 10.3 kN/m2
Unsuitable
Unsuitable
75
6
75
75
10
10
100
150
6
6
2
.
10.3 - 12.1 kN/m
12.1 - 13.8 kN/m2
Unsuitable
Unsuitable
.
13.8 - 17.2 kN/m2
17.2 - 20.7 kN/m2
more than 20.7
kN/m2
100
150
200
6
6
6
125
150
200
6
5
5
150
200
250
4
4
4
VibroTamper
Mass kilogramme
.
.
.
.
.
.
.
50 - 65
65 - 75
More than 75
100
125
200
3
3
3
100
125
150
3
3
3
150
200
225
3
3
3
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.
.
Power
rammer
Mass kilogramme
.
.
.
.
.
150
275
4
8
150
275
6
12
Unsuitable
Unsuitable
Weight of hammer
over 5 kN
Drop 0 m to 0 m
600
Drop over 0 m
600
4
2
600
600
8
4
450 8
Unsuitable
100
more than 150
Dropping
weight
compactor
(a)
The depth of compacted layer is the height by which an embankment is raised by each successive compacted layer.
(b)
The number of passes is the number of times that each point on the surface of the layer being traversed by the
compaction plant (or struck in the case of power rammers or dropping weight compactors).
(c)
The effective width of a pneumatic-tyred roller is the sum of the widths of the individual wheeltracks together with the
sum of the spacing between the wheeltracks provided that each spacing does not exceed 230 mm. Where the
spacing exceeds 230 mm, the effective width shall be taken as the sum of the widths of the individual
wheeltracks only.
(d)
The force per 100 mm width of roll is the total weight on the roller divided by the total roll width. Where a smoothwheeled roller has more than 1 axle the machine shall be assessed on the basis of the axle giving the highest
value of force per 100 mm width.
(e)
Wheel load is the total weight of the roller divided by the number of wheels.
(f)
For items marked with an asterisk (*), the rollers shall be towed by track-laying tractors. Self-propelled rollers are
unsuitable.
(g)
Where a combination of different types of plants are used, the following additional definitions apply:
(i)
The depth of layer shall be that for the type of plant requiring the least depth of layer.
(ii)
The number of passes shall be that for the type of plant requiring the greatest number of passes.
Where a lighter type of plant is used to provide some preliminary compaction only to
assist the use of heavier plant, this shall be disregarded in assessing the above
requirements. ]
4.7.3
Required Field Density
Unless otherwise agreed with the SO, produce a compacted fill material having a field density of at least
the following percentage of the maximum dry density previously established for that material:
(a)
95% in the case of material within 500 mm of formation level.
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(b)
90% in the case of material more than 500 mm below formation level.
Propose for the SOs acceptance to determine field density using the nuclear density meter or the sand
cone replacement method where appropriate.
Notwithstanding compliance with Table 4, verify by site tests at a rate of not less than 3 tests per 300
m2, with a minimum number of 3 tests per site, unless otherwise agreed by the SO, that the required
field density is being achieved and make any adjustments to the compaction methods if necessary.
[Note 1: The compaction values of 90% and 95% are commonly used in many cases but if
structures are to be placed on top, more stringent criteria are required with compaction values of 98%
or even 100%. The selection is project specific and will be dependent on the strength and stiffness
of the fill after compaction - hence the importance of doing CBR and MCV or even triaxial tests on
the compacted laboratory samples as mentioned for comment in Section 02-020:Clause:4.7.1.]
4.7.4
Moisture Content
Maintain the moisture content of the in-situ material during compaction as close to the optimum
moisture content as possible, and within the allowable range determined by the proctor or modified
proctor tests as referred to in Section 02-020:Clause:4.7.1. If necessary, adjust by wetting or drying on
site to consistently maintain the required in-situ field densities.
4.7.4.1
Type 1 Fill Materials
The materials of Type 1 in Section C02-020:Clause:3.1.4.1 shall be transported, laid and compacted
without drying out or segregation.
4.7.4.2
Type 2 Fill Materials
The materials of Type 2 in Section C02-020:Clause 3.1.4.2 shall be transported, laid and compacted
at a moisture content within the range 1% above to 2% below the optimum moisture content
determined in compliance with BS 5835-1 and without drying out or segregation.
4.7.5
Air-Voids
To reduce the potential of collapse compression of unsaturated cohesive fill due to wetting, the moisture
content range at fill placement shall be controlled to achieve a compacted fill with allowable air void
content not exceeding 5%.
4.7.6
In-situ Tests
Refer to SS EN 1997-2 and BS EN ISO 22476 on field testing, and BS EN ISO 22282 on
geohydraulic testing, as appropriate.
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4.7.7
Compacting Different Materials
When materials of widely divergent characteristics are used in fill areas, compact in separate clearly
defined areas for each type of material.
If defining the areas in which each material occurs is not practical, operate the compaction plant base
on the material which requires the greatest compacting effort.
4.7.8
Use of Rock Fill
Assess and evaluate the rock fill on Site for for satisfactory compaction to the requirements of table in
Section C02-020:Clause:4.7.2 for well graded granular soil, compact the fill according to the table.
Refer to Section C02-020:Clause:4.9.3.1 on spreading and levelling for rock fill.
4.7.9
Deterioration of Material
If the material deposited as fill subsequently reaches a condition such that it cannot be
compacted in accordance with the specified requirements, seek agreement with the SO to carry
out one of the following:
(a)
Make good by removing the deteriorated material and replace with Suitable Material.
(b)
Make good the material by mechanical or chemical means to improve its property.
(c)
Cease work on the material until its physical condition is again such that it can be compacted as required.
4.8
Filling: Fill Adjacent to Bridge Abutments, Culverts and Retaining Walls
4.8.1
Not In Use
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S4.8.1
Fill Material
Within the limits defined in Table 5, adjacent to all structures, Special Fill Material as defined in Section
C02-020:Clause:3 shall be provided.
Place fill in horizontal layers of thickness appropriate to the compacting plant used and compact with
care to the density specified in Section C02-020:Clause:4.7 for fill material.
Table 5. Fill Adjacent to Abutments, Culverts and Retaining Walls
Structure
Minimum Width of Special Fill
Bridge Abutment & Wingwalls
2m
Culvert wingwalls
H/3
Retaining walls
H/3 or full width of base, whichever is greater
Barrels of box culverts
H/3
Barrels of pipe culverts
600 mm all round
[Note: H = height of structure]
4.8.2
Filter Drain
Provide a filter drain layer when filling behind structures with weep holes.
The filter drain shall consist of clean, hard and durable broken stones or hardcore conforming to the
grading as set out in Table 6.
Table 6. Filter Drain Material
BS Sieve Size
Percentage by weight passing
63 mm
100
37.0 mm
85 - 100
20 mm
0 20
10 mm
0-5
3.30 mm
0
Place the larger stones adjacent to the weep holes and the smaller particles behind and above the
larger layer.
Unless otherwise specified, the filter drain shall:
(a)
have a width of 300 mm
(b)
extend horizontally across the whole width of the structures
(c)
cover every weep hole vertically by at least 300 mm.
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4.8.3
Placing Fill
For framed structures, bring up fill at both ends of the structure simultaneously with the difference in
levels of fills at both ends limited to 600 mm.
Do not place fill against concrete structures within 21 days after placing concrete unless sufficient
supports have been provided to the walls with the acceptance of the SO.
[Note 1: The SO may require calculations to be submitted to show that no damage to the concrete
structures will be caused by backfilling earlier than 21 days.]
4.8.4
Compaction
Place fill in horizontal layers of thickness and compact using the appropriate plant in compliance
with Section C02-020:Clause 4.7.2.
The degree of compaction shall be at least 95% of the maximum dry density achievable of the material
unless otherwise agreed with the SO.
Do not use heavy compaction equipment close to the back of the wall.
[Note 1: The effect of compaction shall be taken into account in the design, and the allowable loading due
to compaction equipment shall be clearly specified.
Note 2: Structural fill or special fill is often better to compact to 98% which should be achievable for
the type of material used as special fill, even when using hand held compacting equipment.]
4.9
Filling: Embankments and Fill Slopes
4.9.1
Material
Ensure Suitable Materials are being used for embankment fill, including materials which may be
initially wetter than specified but become suitable after drying. For capping layers which comprise
materials used to improve the performance of the foundation soils before laying the sub-base, and to
protect the subgrade from damage by construction traffic, ensure specified materials, including
topsoil are placed to a consolidated thickness below the formation level.
4.9.2
Build-up and Compaction
Unless justified as impractical, build up embankments evenly over the full width and maintain a sufficient
cambered surface to enable ready drainage of surface water. Compact fill material as per Section C02020:Clause 4.7.
4.9.3
Rock Fill
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4.9.3.1
Spreading and levelling
Rock used in rock fill embankments shall be of maximum particle size of 300 mm so that it can be
deposited in horizontal layers, each not exceeding 500 mm in compacted depth and extending over
the full width of the embankment except for any specified external cover to slopes or new formation
level. The materials shall be spread and levelled by a crawler tractor weighing not less than 15
tonnes. Each layer shall consist of reasonably well-graded rock and all large voids with averaging
dimension of exceeding 150 mm shall be filled with broken fragments before the next layer is placed.
The top surface and side slopes of embankments so formed shall be thoroughly blinded with
approved fine graded material to seal the surface.
There shall be a transition layer between rock fill and earth fill or the top 300 mm below formation level
of at least 300 mm compacted thickness. This shall consist of uniformly-graded crushed rock between 6
mm and 150 mm as approved by the SO.
Refer to Section C02-020:Clause 4.7.8 on the assessment and evaluation of rock fill for compaction
method to be approved by the SO.
Unless otherwise required or directed by the SO, spread and level each layer of rock fill and
systematically compact by at least 12 passes using the following methods as appropriate:
(a)
A towed vibratory roller with a static load per metre width of roll of at least 1 800 kg, or with a static load
per 25 mm width of roll of at least 80 kg.
(b)
A grid roller with a load per metre width of roll of at least 8 000 kg, or with a load per 25 mm width of roll
of at least 200 kg.
(c)
Other approved plant.
[Note 1: Each horizontal layer of 500 mm is the maximum thickness. Normally compacted thickness of
rockfill layers should be not be less than 1.5 x the maximum particle size.]
4.9.3.2
Finishing
Fill surface voids with broken fragments before the next layer is placed.
Thoroughly blind the top surface and side slopes of embankments with approved fine graded material to
seal the surface.
[Note 1: Depending on the rockfill and the end use of the embankment, agree with the SO on the use
of geotextile layers with the blinding layer if there is a risk that the voids between the rock fill are not
filled and material may migrate from the embankment body into these voids.]
4.9.3.3
Use of Isolated Boulders
Isolated boulders each within the range 0.02 m3 to 0.10 m3 in size may be used provided that the
specified compaction requirements are met and no stone exceeding 0.02 m3 shall be placed less
than 0.5 m below the top of the embankment fill.
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4.9.4
Embankments Bridging Culverts, Pipe Drains and Bridges
In constructing embankments up to and over culverts, pipe drains and bridges, bring the
embankments up equally on both sides. Filling may proceed over widths less than the full width
of the embankment and in steps not exceeding the depth of one layer above the adjoining
area of fill.
4.9.5
Construction Traffic
During construction, control constructional traffic uniformly over the full width of the embankments.
If the intention is to use the surface of embankments for constructional traffic before trimming to
formation level, bring up and maintain the area to a level not less than 150 mm above formation
level before allowing constructional traffic on the surface. In areas of shallow filling where the ground
level is within 300 mm of formation level, bring up and maintain the surface level at least 300 mm
above formation level.
Make good any damage caused to the subgrade.
[Note 1: Many situations require control construction traffic uniformly over the full width of the
embankments. However, it depends on embankment materials and its trafficability particularly if using
cohesive fill. If haul roads are required and much of construction traffic should be kept off as this is
particularly critical for formation surface.
Refer to the guidance in BS 6031.]
4.9.6
Formation of Slope Faces
(a)
Form the slope faces of embankments by overfilling, cutting back and trimming neatly to the determined profile. The
formed slopes shall satisfy the requirements for as provided in Section C02-020:Clause:2.6.
(b)
Where an embankment is to be constructed on a hillside, or where the natural surface falls away at a slope steeper
than 1 vertical to 4 horizontal, cut a horizontal bench to support the toe. The minimum width of the bench shall be
one third of the vertical height of the fill (measured from the toe) but not less than 600 mm.
(c)
Where an embankment is to be constructed on the slopes of existing embankments exceeding one vertical to four
horizontal, the existing slope shall be cut in the form of horizontal terrace over the full area to be covered by the
new fill. Cut the terraces in minimum width of 600 mm and stepped progressively as the fill progresses.
(d)
At 1.2 m below the embankment surface, no point on the completed slope shall vary from the required face by more
than150 mm measured at right angles to the slope. At greater than 1.2 m below the surface, no point on the
completed slope shall vary by more than 300 mm.
[Note 1: Refer to Section C02-020:Clause 4.4.4 on the requirements on drainage and also
Technical publication UK TRL PPR 314 on drainage of earthworks slopes.]
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4.10
Method of Measurement
All measurement of excavation shall be based on the net dimensions between the external faces
of the permanent construction.
Levels shall be taken and certified before and after excavation, to calculate the volume for each
method of excavation. Levels taken shall be subject to approval by the SO.
Maintain all boundary markers, bench marks and other such reference points which shall be offset
before commencement of the Works. All offsets shall be carried out by a qualified surveyor.
Should any such markers be disturbed or destroyed, these references shall be replaced immediately and
the SO informed of such replacement.
4.11
Hardcore Under Concrete Slabs
Use material as stated in Section C02-020:Clause:3.4. Provide thicker layer than specified if necessary to
make up levels from stripped site levels to underside of slabs.
[Note 1: For many small projects, a layer of hardcore beneath a ground-bearing slab will be adequate.
The intention of this clause is to simplify drawings by making it unnecessary to show the precise
thickness of hardcore but only minimum thickness required.]
4.12
Use of Geotextile Sheet
4.12.1
General
(a)
Protect from exposure to light, except for a maximum of 5 hours during laying. Protect from all materials listed as
potentially deleterious by the manufacturer.
(b)
Before commencing laying, remove humps and sharp projections from the ground and fill hollows. Do not stretch or
bridge the geotextile over irregularities and ensure that the specified lap is maintained.
(c)
Take care to avoid damage to geotextile by vehicles, plant or by tipping material from excessive height. Do not allow
construction traffic over geotextiles until covered by the full thickness of fill.
(d)
Temporarily weight edges of sheet with fill and lay a maximum of 15 m of geotextile before covering to prevent
uplift. Place fill as soon as possible after laying and within a maximum of 24 hours.
(e)
Place geotextile patches over tears with minimum lap of 300 mm beyond extent of damage and cover immediately
to retain in place.
(f)
Geotextiles are adversely affected by exposure to ultraviolet light. Minimum lap must be maintained unless joints are
stitched or stapled, even if laying in strong winds. Both of these requirements are best achieved by not laying more
geotextile than can be covered by fill in the same day.
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4.12.2
Jointing
Propose and comply with one of the following methods of jointing:
(a)
300 mm overlaps: Overlaps to be 300 mm to 1 000 mm, with the wider overlap necessary on very soft subgrades
to allow for movement when trafficked by vehicles. Overlaps shall be weighted down immediately with small
amounts of aggregates.
(b)
Single-stitched prayer seam with high tenacity polyester thread: Carry out sewing with portable stitching machines
using high tenacity polyester or polyester/cotton thread in a single or double stitch to form a prayer seam
configuration. A single line stitch is generally adequate.
(c)
Single welt with two rows of staggered, corrosion resistant staples - Carry out stapling on welted seams with two rows
of staggered, corrosion resistant, staples.
[Note 1: Seam strengths are likely to be considerably lower than those achieved by sewing.]
4.13
Preparation for Cultivation with Spot and Close Turfing
Trim and cultivate cut or filled areas that are to be turfed as soon as possible after completion of the
earthworks.
For turfing requirements refer to the architectural specifications or drawings and G01-010 General
Requirements.
4.14
Seeding
Seeding or hydroseeding shall be carried out as soon as practical on slopes and other areas as
shown in the drawings and/or as directed by the SO.
Submit to for the SOs approval, in advance of the proposed work, full details of the proposed method of
seeding and hydroseeding. The information submitted shall include, but not necessarily be limited to, a
full description of the following aspects of the Works:
(a)
Penetration of the areas to be seeded or hydroseeded, including if appropriate the amount of topsoil to be
used and its method of application.
(b)
Details and results of investigations to determine which types of grass or legume are comparable with the
soil in the areas to be seeded.
(c)
Types of grass and legume (if any) and strains of seed to be used, and the function, root and growth
characteristics of each type.
(d)
Rates of application of the grass and legume seeds.
(e)
Composition of fertiliser to be used at the time of seeding and its rate of application.
(f)
Composition of fertiliser to be used after seeding, the times of application after seeding, and the rates of
application.
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(g)
Type of mulch to be used and its method and rate of application.
(h)
Amount of lime or other chemicals (if any) to be applied to improve the soil before, during and/or after
seeding.
(i)
Type and amounts of binding agents to be applied with the seeds, mulch, fertiliser, etc., as appropriate.
(j)
Proportions and methods of preparation of the seeding mix.
(k)
Equipment and method to be used in preparing and placing the seeding mix and other materials.
(l)
Cultivation and after-care if the seeded areas, including rates and frequencies of watering, fertilising,
grass cutting and general maintenance for at least 1 year after seeding.
(m)
Time after seeding required for establishing permanent, dense growth of grasses, which will require
minimal maintenance.
(n)
Guarantees of success of the seeding work.
All grass shall be regularly watered until the vegetation is satisfactorily established to the
satisfaction of the SO. Any dead grass shall be replaced.
Hydroseeding shall be carried out after the proposed slope surface exceeds 1 000 m2 or within 2 weeks
after cutting or 1 week during monsoon season, whichever is earlier on all slopes and other areas as
shown in the drawings and/or directed by the SO.
4.15
Monitoring of Fill Performance
Provide and arrange for the performance of the fill, once placed, to be monitored. Propose for the SOs
acceptance and implementation on monitoring the performance which can consist of one or more of the
following as appropriate:
4.15.1
(a)
Optical levelling of surface markers
(b)
Standpipes or piezometers
(c)
Load tests
(d)
Other methods as required or directed by the SO.
Instrumentation
Arrange for the supply of the instruments as specified, or required or directed by the SO and inform the
SO of the date on which the equipment installation shall commence. Provide the SO with the following
details:
(a)
A full description of the nature and type of instrument and the purpose it fulfils.
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(b)
The number required and the location and or depth at which each instrument is to be installed.
(c)
The frequency, accuracy and duration for which any readings are to be taken.
4.16
Accuracy and Tolerance
4.16.1
General
Comply with EN 16907 except where noted below.
4.16.2
Permitted Deviations (PD) from Formation Levels
(a)
Beneath mass concrete foundations: ±25 mm.
(b)
Beneath ground bearing slabs and reinforced concrete foundations: ±15 mm.
(c)
Embankments and cuttings: ±50 mm.
(d)
Ground abutting external walls: ±50 mm, but such as to ensure that finished level is not less than 150 mm below any
damp proof course.
4.16.3
Blinding to Fill
Permitted deviations on surface level: +0, -25 mm.
[Note 1: The zero plus tolerance is to ensure that minimum thickness of overlying concrete slabs is
maintained.]
5
VERIFICATION AND SUBMISSIONS
5.1
Submissions
5.1.1
Method Statement
Before work commences, provide the SO with a method statement, including at least the following
information as relevant:
(a)
Proposed excavation and compaction plant
(b)
Maximum depth of each compacted layer
(c)
Minimum number of passes per layer
(d)
Method of treating slopes
(e)
Protection of formation and slopes
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5.1.2
(f)
Proposed temporary works
(g)
Dewatering control
(h)
Ground anchors, etc.
Programme of Works
Submit to the SO prior to the start of the Work unless otherwise agreed.
5.1.3
Additional Site investigation Factual Report
Extend to the SO, a copy of the factual report for additional site investigation conducted under Section
C02-020:Clause 1.4.6.2.
5.1.4
Temporary Works Design
5.1.4.1
General
Before commencement of Work, submit details of proposals for supporting the sides of all excavation
which have slopes steeper than 1:2, or less if poor conditions exist, or exceeding
1.5 m in depth which will be formed during the course of the Works.
Provide adequate information to justify the adequacy of the proposals, if so requested. [Note 1: A
risk assessment is generally required based on actual ground conditions and the
activity to be undertaken to determine where temporary supports to excavations are required. Though 1.5
m has been taken as the depth lesser which these are not required, this will not always be the case.]
5.1.4.2
Flow chart for ground movement monitoring
Submit a flow chart clearly indicating the proposed line of actions and the persons in-charge in
connection with the actions to deal with critical ground movements for the SOs acceptance.
5.1.4.3
Use of ground anchors
Where there are use of ground anchors as part of the temporary works, submit to the SO a detailed
specification for the anchors as part of the method statement.
Provide an appraisal of the suitability of the proposed anchor installation in relation to the ground
conditions, the possible effects on adjoining structures and services, and the rights of adjoining owners
whose structure or land may be affected.
Ensure all necessary approvals and permits have been obtained from the authorities.
5.1.5
Quality Control Plan
Prepare and submit the quality control plan for SOs acceptance prior to starting work.
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5.2
Inspection and Tests of Temporary Works
Inspect the temporary works scheduled as follows:
(a)
Intermediate inspections if the works are in place for more than 1 week
(b)
If there has been a change in loading conditions, including impact
(c)
After any adverse weather conditions
Submit a method statement for acceptance indicating the proposed frequency and details of the
inspections.
5.2.1
5.3
Pull Out Tests for Ground Anchors
(a)
Pull-out test shall comply with SS EN 1997-1 and BS EN 1537.
(b)
Propose numbers of tests for acceptance in the method statement.
(c)
Perform preliminary pull-out tests prior to the installation of working ground anchors to verify the design
capacity of ground anchors.
(d)
Carry out acceptance tests on the working ground anchors.
Fill Material Samples
At least 21 days before filling work commences, submit full details of the sources and types of the
proposed filling materials together with 25 kg representative samples of each type from each source.
On request from the SO, collect and dispose of these samples.
At the same time, deliver to an accepted accredited laboratory, sufficient representative samples
of each material for the specified tests, at a rate of one set of tests per sample.
[Note 1: All materials submitted should be examined, described (and photographed), and samples
retained for comparison with those supplied to the Site. Tests should be made to determine the
properties (grading, plasticity, SO3 content, density, California Bearing Ratio, CBR, etc.) relevant to
the Works and as described in subsequent clauses, and to provide a basis for comparison with
materials supplied to site.]
5.4
Testing of Fill Materials
Carry out the following tests according to SS EN 1997-1 and SS EN 1997-2 and relevant
standards including BS 1377 on all proposed fill materials at the rate of one test for each
representative sample:
(a)
Classification
(b)
Ground Investigation
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(c)
Determination of the particle size distribution
(d)
Determination of the plasticity index (of material passing the 425 micron BS sieve; % of material retained
to be reported)
(e)
Determination of the total sulphate content
(f)
Determination of the ten per cent fines value
Carry out the following tests (but not limited to the list below) according to SS EN 1997-2 and relevant
standards as required for certain materials when specified or directed by the SO:
5.4.1
(i)
Determination of the dry density/moisture content relationship of granular soil (vibrating hammer
method).
(ii)
Determination of the California Bearing Ratio.
(iii)
Determination of sand-geotextile frictional behaviour by direct shear.
(iv)
Determination of strength of aggregates.
Additional Tests
When directed, test all imported fill for compliance with specified limits on contamination to ensure that
material is "clean" relative to the proposed end use. Propose and submit the specific criteria,
schedule and timing of tests required to SO for acceptance.
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(6) C02-030-01 Diaphragm Wall
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1
GENERAL
Read this Section with G01-010 "General Requirements" and all other contract documents
1.1
Scope
This Section covers the requirements for the construction and installation of diaphragm walls as an
embedded retaining wall type. Other types of embedded retaining walls are covered in:
C02-030-02 Sheet Piling
C02-030-03 Contiguous Bored Pile Walls and Secant Bored Pile Walls
The walls may be used solely to form embedded retaining walls resisting principally horizontal loads, or to
support vertical loads.
1.2
Related Sections
Read this Section in conjunction with the relevant requirements of the following sections:
1.3
C01-020
Condition Survey
C02-010
Ground Investigation
C02-020
General Earthworks (Excavation and Filling)
C02-050
Instrumentation and Monitoring
C03-010
Concrete Construction Generally (including recycled material)
C03-020
Reinforcement
C04-030
Pile Testing
Standards, Codes, Regulations and Technical References
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1.3.1
Standards and Codes
Unless otherwise agreed by the SO, ensure all of the Works comply with the relevant requirements
of the standards and codes listed below or referenced in the body of the Specification. Alternative
standards and codes may be proposed for approval by the SO, provided it can be demonstrated that
the alternative standards and codes comply with the requirements of the standards specified. All
standards and codes quoted are the current version, unless specific year references are noted.
In the event that the standards or codes are partially superseded or have become obsolete, refer to
the current edition or the approved substitution for the relevant clauses.
Singapore Standards
SS EN 1992-3
Eurocode 2: Design of concrete structures - Part 3: Liquid retaining
and containment structures.
SS EN 206
Concrete - Specification, Performance, Production and
Conformity
SS CP 79
Code of practice for safety management system for construction
worksites
SS 544-1
Concrete - Complementary Singapore Standard to SS EN 206 Part 1:
Method of specifying and guidance for the specifier
SS 544-2
Concrete - Complementary Singapore Standard to SS EN 206 Part 2:
Specification for constituent materials and concrete
Other Standards
BS EN 1538
Execution of special geotechnical work - Diaphragm Walls
BS EN 1008
Mixing water for concrete, specification for sampling, testing and
assessing the suitability of water
BS EN ISO 17660
Welding. Welding fof reinforcing steel. Load bearing welded joints
BS 5228-1
Code of practice for noise and vibration control on construction and
open sites - Part 1: Code of practice for basic information and
procedures for noise and vibration control
BS 5228
Code of practice for noise and vibration control on construction and
open sites - Part 4: Code of practice for noise and vibration control
applicable to piling operation
BS 8002
Code of practice for earth retaining structures
ISO 10414-1
Petroleum and natural gas industries - Field testing of drilling fluids Part 1: Water based fluids
ISO 13500
Petroleum and natural gas industries - Drilling fluid materials Specifications and tests
DIN 4126
Stability Analysis of Diaphragm Walls
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1.3.2
Technical References
Refer to the following technical reference for guidance in carrying out the Works:
CIRIA C760
Guidance on embedded retaining wall design
EFFC/DFI
EFFC/DFI Guide to Tremie Concrete for Deep Foundations (2nd
Edition, 2018)
EFFC/DFI
EFFC/DFI Guide to Support Fluids for Deep Foundations (1st Edition,
2019)
API RP 13B-1
API Recommended Practice for Field Testing Water-based Drilling
Fluids
.
.
1.4
Trade Preamble
1.4.1
Development of Design Requirements
The notional design of the diaphragm wall works is indicated in the drawings, together with the
construction sequence, schematic strutting or ground anchor system indicated in terms of the installation
levels, the required stiffness and preloading. Based on the information provided, undertake and provide
for the SOs acceptance the following which shall be carried out by appropriately qualified, competent
and experienced personnel and PE:
(a)
Construction or design verification checks based on actual ground conditions to confirm the required
penetration length for toe stability, horizontal and basal stability requirements, and the structural and
geotechnical capacity. Size and provide all temporary or permanent propping elements and walers,
ground improvement, where necessary, for improved horizontal restraint required for the diaphragm walls,
and take into all necessary considerations that the required control on wall deflection can be achieved.
(b)
Prepare a response plan in the event that the temporary and or permanent strutting elements do not
perform as expected in the design in controlling the wall deflection, and in the event that measures
taken to control ground movement and vibration do not perform satisfactorily. Establish and indicate the
alert levels and work suspension levels for forces and deflection of the diaphragm wall structure in the
drawings. The response plan shall be feasible for timely implementation with due consideration of the
construction sequence and site constraints.
(c)
Prepare and submit all design and construction sequence, including drawings and reviews that shall be
endorsed by appropriately qualified, competent and experienced PE to the SO for his acceptance.
Take into account the design requirements as set out in C02-030-01: Clause:2.1 in this Section.
Submit the CV of the personnel and specialists where applicable to the SO for acceptance.
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1.4.2
Layout Drawings
Engage qualified and experienced personnel to prepare co-ordinated layout drawings for the diaphragm
wall panels.
Submit the drawings to SO for acceptance prior to commencing the installation works.
1.4.3
Co-ordination with Other Works
Co-ordinate with other contractors who may carry out other works at the same time at the Site. Take
account of site access, space occupation, safety and safeguarding of adjoining properties and each
other’s works.
1.4.4
Upholding of Adjoining Properties
Accept responsibility for the upholding of the adjoining buildings and roads, footpaths, etc., where
applicable, together with the mains and services from the time of taking possession of the Site
through the duration of the Works.
Adequately maintain roads and footpaths within and adjacent to the Site and keep clear of mud and
debris.
1.4.5
Verification of Site Information
1.4.5.1
Site Surveys
Verify and be satisfied that the information given in the existing site survey plans provided are accurate. If
necessary, engage a Registered Surveyor to carry out additional site survey before commencing any
work.
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1.4.5.2
Additional Site and Ground Investigation
Carry out additional ground investigation where additional information is needed for the Works or when
directed by the SO. Carry out the Works in compliance with Section C02-010 "Ground Investigation.
The permeability, strength of the subsoils and the groundwater level are key parameters to be
ascertained to determine the suitability of the execution method and equipment and the required
penetration depth, and to ensure overall stability and seepage cut-off.
Carry out the boreholes progressively, prior to commencement of the Works in areas, according to the
Contractor’s construction programme. On completion of drilling, backfill the boreholes with a suitable
bentonite/cement.
Where rock is encountered, carry out sufficient number of boreholes before the panel excavation to
establish the quality and grade of the rock for design and execution requirements. Where cavity is
suspected from existing geological or published information in the area, e.g. in limestone, carry out
adequate number of boreholes for sufficient information to carry out any pre-treatment works that are
necessary before diaphragm wall installation commences.
Submit the location and schedule for the boreholes to the SOs acceptance, prior to carrying out the
Works. On completion, prepare the Site Investigation Report and submit to the SO for acceptance.
1.4.5.3
Groundwater level
Verify the data on groundwater level from available ground investigation reports. Carry out additional
water standpipes and piezometers if deemed necessary or as directed by the SO.
1.4.5.4
Contamination
Verify information on contamination identified or believed to be present on site.
In the event that contamination is either positively identified or suspected, draw to the attention of all
personnel working on site together with the need to take any precautionary measures in handling
contaminated materials, groundwater and obnoxious vapour from the ground.
1.4.6
Supervision of the Works
Engage a qualified, competent and suitably experienced site engineer with the SOs acceptance, to
supervise the field works. Information on items to be checked or requiring monitoring during construction
shall be clearly identified and made known to the supervising personnel.
Site Supervision Plan (SSP) for supervision of the structural and geotechnical building works shall be
prepared and submitted by qualified, competent and experienced PEs to the relevant authorities, and
in accordance with the current guidelines issued under the Building Control Act and Regulations.
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1.4.7
Quality Control Plan
Submit and work to a quality control plan as agreed with the SO. Refer to G01-010: Clause 1.4.7.
1.5
Definitions and Abbreviations
1.5.1
Definitions
1.5.1.1
Accredited Testing Laboratory
An organisation or laboratory accredited under the SAC-SINGLAS to carry out tests required by the
Specification.
1.5.1.2
cement
Include all mineral admixtures such as PFA, GGBS, silica fume, etc. that have cementitious properties as
in SS EN 197-1.
1.5.1.3
obstructions
Include concrete, reinforced concrete, solid brickwork, sheet piles and the like of man-made object, met
during drilling, but excluding those met on the surface of the ground
1.5.2
Abbreviations
No item.
2
PERFORMANCE REQUIREMENTS
2.1
Verification of Performance during Execution
When carrying out the performance verification as set out in C02-030-01: Clause:1.4.1, take into
account the following considerations.
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2.1.1
Wall Movements
The required size of diaphragm wall system is shown on the drawings, including the wall penetration
depth and the size of all permanent supports. A schematic temporary propping system indicated in
terms of the installation levels, the required stiffness and preloading are also shown in the drawings,
where applicable.
Based on the actual ground condition encountered, verify the wall penetration depth and the
adequacy of diaphragm wall system as indicated in the drawings and in accordance with SS EN
1997. The diaphragm wall movements shall be checked and reviewed throughout the execution to
ensure that the wall movements are within the allowable limits as specified or indicated in the
drawings and in accordance to the requirements of the relevant authorities. The diaphragm walls shall
withstand all loads on it, including those due to hydrostatic pressure, earth pressure, surcharge loads,
overburden, effects of surrounding properties and varying load conditions due to different stages of
construction. Check that the application of partial factors assumed in the design and control on wall
movement are verified by taking into account the construction effects and field performance of the
intended temporary supporting system.
The verification shall be in accordance with SS EN 1997. Check that the ultimate limit states (ULS)
shall not be exceeded when appropriate load combinations and partial factors are applied in
accordance with SS EN 1997. In addition, control of wall deflection shall also satisfy serviceability limit
states (SLS) and the requirements of Building Control Authority
The verification of performance shall be in accordance with SS EN 1997 and SS EN 1992 as
appropriate when the diaphragm wall is used as water retaining structure.
[Note 1: Refer to CIRIA 760 on the use of appropriate factors for permanent and temporary works in
selecting the diaphragm wall section.]
[Note 2: Temporary and permanent works shall be treated with equal importance and shall be well coordinated without ambiguity at all stages of design and construction. When an observational
approach is adopted, a highly co-ordinated site team would need to be employed, and clearlydefined protocols for decision-making and monitoring requirements would have to be in place before
construction commences.]
2.1.2
Embedment for Load Bearing
If the diaphragm walls are also used for vertical load bearing purposes, verify the required
embedment length, taking into account the actual ground conditions and the results of load tests of
preliminary elements.
2.2
Use of Support Fluid
Where support fluid is used, fulfill the following requirements:
(a)
Provide continuous support of the excavation.
(b)
Do not form a thick filter cake layer prior to concreting.
(c)
Have the ability to keep solid particles in suspension.
(d)
Be capable of being easily displaced and the interface layer remains on the top of the rising concrete during
concreting.
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(e)
Limit the penetration of support fluid into the surrounding soil.
(f)
Does not pollute the ground and groundwater at all stages.
(g)
Does not coat the reinforcement such as to impair the bond between the reinforcement and concrete.
Bentonite, polymer or a mixture of bentonite and polymer support fluids may be considered for these
requirements.
Testing of support fluid shall be carried out to demonstrate compliance of limits as specified in BS EN
1536 or ICE specification for piling and embedded retaining walls if applicable, or European
Federation of Foundation Contractors and Deep Foundations Institute (EFFC/DFI) Guide to
Support Fluids for Deep Foundations, or the manufacturer’s instructions shall be complied with, as
appropriate.
2.3
Watertightness
Take all necessary measures to ensure that the walls formed are substantially watertight, that is, free
from running or percolating water or seepage water. Seal all damp patches. When total damp patches
exposed on the excavated face of the wall exceeds 10% of the visible area or any individual damp
patch is found to be more than 4 m2, repair works shall be carried out.
[Note 1: For guidance, refer to BS 8102 "Code of Practice for protection of below ground structures
against water from the ground", Table 2; and B1.9 of ICE "Specification for Piling and Embedded
Retaining Walls", 3rd Edition.]
3
MATERIALS
3.1
Source of Materials
Do not change sources of supply until it has been demonstrated that the materials from the new
source can meet all the requirements of this Specification.
Remove from site any materials that fail to comply with this Specification.
3.2
Support Fluid
3.2.1
Bentonite
3.2.1.1
Source
Bentonite supplied to the Site shall comply with BS EN 1538.
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3.2.1.2
Performance of Bentonite Slurry
Include proportion of bentonite in the slurry by taking into account the rheological properties of the
bentonite such that the slurry is sufficient to maintain the stability of the excavation in the ground
conditions encountered.
The density and lowest head of slurry above ground water shall together be such as to ensure the
stability of the trench excavations throughout its entire depth.
3.2.1.3
Use
Use in accordance with the manufacturer’s instructions unless there is a demonstrable reason to do
otherwise.
3.2.1.4
Mixing
Mix bentonite powder thoroughly into the water by a suitable high shearing action mixer until all lumps
have been broken up and dispersed within the mix, to make a suspension which will maintain the
stability of the panel excavation for the period necessary to place concrete and complete construction.
Where saline or chemically contaminated groundwater occurs, take special precautions to modify the
bentonite suspension or pre-hydrate the bentonite in fresh water so as to render it suitable in all respects
for the construction.
3.2.1.5
Quality Control of Bentonite
If bentonite is used, in any 100 tonnes of bentonite supply, moisture content shall not deviate more than
±2%. Residue of diameter greater than 75 µm shall not exceed 4%. Bentonite slurry properties
obtained at the recommended dosage by the manufacturer/ supplier shall conform to Tables 1 and 2
of BS EN 1538.
3.2.1.6
Reuse of Bentonite
Upon reuse, the density, maximum sand content and pH of bentonite shall to comply with the criteria as
set out in Tables 1 and 2 of BS 1538.
3.2.1.7
Storage
Store solid additives in separate waterproof stores or containers which will prevent the materials
from becoming contaminated.
Store bentonite in dry cool conditions. Take particular care with bulk storage to prevent balling together of
bentonite powder due to dampness, or deterioration of properties due to dampness and heat.
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3.2.1.8
Testing
Allow for one sample of bentonite powder per panel to be tested under the same conditions as those
under which testing was carried out by the supplier or manufacturer, at the date on which work
commences on the panel.
[Note 1: Refer to EFFC/DFI, Guide to Support Fluids for Deep Foundations.]
3.2.2
Alternative Materials
If alternative drilling fluid such as polymer is to be used in lieu of bentonite, submit proposals for the
additional or alternative ingredients and admixtures to the support fluid for the SOs acceptance.
These proposals should include samples and full details, including the supplier and manufacturer of
such ingredients. Any such materials must not detrimentally affect the concreting, or formed
concrete. Comply with ISO 13500.
Polymers can be used as the main component for support fluid or as additives to bentonite to improve
their rheological properties. Different type of polymer exists, ranging from natural gums, cellulose
modified and synthetic high molecular weight polymers (PHPA - partially hydrolysed
polyacrylamide).
Use of polymer fluid should rely on the Contractor’s experience and recommendation based on past
experience on similar ground conditions or by performing a trial trench test to confirm support fluid
characteristics and performance suitable to the specific project and to ensure trench stability during
panel excavation.
Testing of polymer solution shall conform to ISO 10414-1.
3.3
Water
Water shall be clean and free from harmful matter in solution or suspension.
If taken from a source other than the Public Utilities Board, water shall be tested in accordance with SS
EN 206.
3.3.1
Water for Mixing Bentonite
Water used for dispersion of bentonite shall be as nearly neutral in pH as practicable. Saline water or
water contaminated by salts shall not be used unless tests are performed to show compliance with
bentonite slurry performance, as required in BS EN 1538.
3.4
Concrete
General requirements of concrete and constituent materials shall refer to SS EN 206, SS 544 Part 1
and SS 544 Part 2. In particular for specific diaphragm wall concrete shall additionally refer to Annex
D of SS EN 206. The concrete mix design shall satisfy the specification of concrete and shall take
into account the following:
(a)
the need for a high resistance against segregation
(b)
the need for adequate plasticity and good cohesiveness
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(c)
the need to flow well
(d)
the need to be able to compact adequately by gravity
(e)
the need of sufficient workability retention for the duration of the placement procedure
(f)
the need of a concrete final set within 20 hours.
In order to minimise segregation, aggregates should be continuously graded. The specified upper value
of aggregate size, Dupper shall not exceed 32 mm and -¼ of the clear space between the
longitudinal bars.
3.4.1
3.4.2
Minimum Fines and Cement Content
(a)
The minimum cement content for any mix shall be 325kg/m³.
(b)
For concrete placed by tremie tube, this value shall be 380kg/m³ for a Dmax of 20 mm.
(c)
Where the concrete is exposed to sea water, it shall follow the requirements of SS 544- 1 and 544-2 for
resisting the specified exposure class.
(d)
Sand content (D ≤ 4mm) shall be greater than 40% by mass of the total aggregate.
(e)
Fines ((D ≤ 0.125mm) shall be between 400 kg/m3 to 550 kg/m3 in the concrete (including cement and
other fine materials).
Water and Cement Ratio
The specified maximum water and cement ratio shall not be greater than that given in the provisions
valid in the place of use for resisting the specified exposure classes, and 0.60, whichever is the
lower value.
[Note 1: Refer to SS EN 206, Annex D on additional requirements for concrete to be used in
diaphragm walls.]
3.4.3
Fresh concrete
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3.4.3.1
Consistency
Slump or slump flow measured at the time of discharge shall be in accordance with the standards
shown in Table 1, unless otherwise accepted by the SO.
Do not use a concrete pump to place tremie concrete directly into the pile shaft unless approved
by the SO.
Table 1. Slump and slump flow at time of discharge according to Standards
Class of Workability
Target Slump
Flow
BS EN 12350-8
mm
Slump
BS EN 12350-2
Minimum
(mm)
Maximum
(mm)
Typical Condition of Use
A
Not applicable
120
180
Placed into water-free
B
450±50 (*)
180
240
Where concrete is to be
placed by tremie under
drilling fluid or water
* Unless otherwise accepted, depending on special features with the approval of the SO.
3.4.3.2
Workability Retention
Retention of specified properties of fresh concrete, such as slump and slump flow, for a specified
duration of time. The workability retention should be 3 hours minimum with an absolute minimum slump
limit of 160 mm at 3 hours or equivalent consistency using a slump flow.
3.4.3.3
Stability
The stability of concrete is defined by the resistance of a concrete to segregation, bleeding and filtration.
This is quantified primarily based on bleeding and filtration tests. The stability tests in the EFFC/DFI
guide are in Table 2 below:
Table 2. Stability tests in EFFC/DFI guide
.
3.4.3.4
Specified Range
Tolerance
Observation
Bleeding
≤ 0.10 ml/min
+ 0.02 ml/min
.
VSI
0
-
Mandatory if Slump Flow
Filtration
≤ 22 ml
+3 ml
.
Static Segregation
≤ 10%
+2%
.
Apparent Viscosity
Using the inverted test or modified cone outflow test as defined in the EFFC guide. The recommended
range is 2 sec to 7 sec.
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3.5
Additions and Admixtures
Additions and admixtures when used in the concrete mix shall comply with SS EN 206.
3.6
Backfill Materials
Use granular fill or lean mix concrete as backfill above any cut-off level for structural concrete and take
to the ground level. Unless otherwise directed, backfill not less than 24 hours and not more 3 days after
placing of concrete in the diaphragm wall panel.
3.7
Reinforcement
For general requirements of reinforcement, refer to Section C03-020: Clause:3. The steel elements
used in the diaphragm walls shall comply with SS EN 10080.
4
WORKMANSHIP
4.1
Continuous Construction
Unless otherwise accepted by the SO, carry out the construction of panels, including corner panels to be
continuous once excavation has commenced.
Provide measures to prevent the formation of bentonite cake. Minimise the time panels stay open at
night or during weekends. In the event of unavoidable circumstances when the panels need to stay open,
get the prior approval of the SO with a method statement stating the protection measures adopted.
[Note : Refer to EFFC/DFI, Guide to Support Fluids for Deep Foundations and EFFC/DFI,
Guide to Tremie Concrete for Deep Foundations.]
4.2
Length of Panel
Plan and submit in method statements, the length of the panels to be concreted to the acceptance of
the SO. Consider shorter panel length to minimise ground movement where necessary.
4.3
Ground Movement Monitoring
Carry out surveys and monitoring of movement and vibration in adjacent structures and services
in the course of the Works in accordance with accepted method proposals.
4.4
Guide Walls
Design and construct these elements taking into account the actual site and ground conditions and the
equipment to be used on site to ensure stability. Design the guidewalls for the vertical and horizontal
loads specific to the project.
Construct the walls in reinforced concrete or other suitable material, to a minimum depth of 1 m.
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4.5
Void Formers
Obtain approval of the size, type and position of all void formers, inserts and connectors before work
proceeds. Unless otherwise specified or approved, form all void formers and all inserts and
connectors cast in at the time of concreting the panel. All void formers, inserts and connectors shall
be formed to minimise obstruction to the free flow of concrete. Co-ordinate and adjust the lengths and
layout of the panels so that no single void former or block-out will straddle 2 adjacent panels.
4.6
Stability of Excavation Using Support Fluid
Where the use of support fluid is accepted for maintaining the stability of a trench, maintain the level of
the fluid in the excavation so that the fluid pressure always exceeds the pressures exerted by the
soils and external groundwater with adequate factor of safety to ensure stability of the strata near
ground. Always maintain slurry level above the level assumed in the approved trench stability
calculations and above the bottom of the guide wall.
Maintain the fluid level at a level not less than 1.5 m above the level of the external groundwater,
unless it can be demonstrated that a lower level provides adequate stability and controls ground
movements to an acceptable level. Allow a freeboard of minimum 20 cm between the slurry to top of
the guide wall.
Maintain availability for immediate use, a sufficient quantity of slurry to allow for any sudden loss.
Should the loss continue despite the addition of the slurry and the stability of the trench be placed at
risk, immediately advise the SO and take such immediate remedial action (backfill with LSS or lean
mix concrete) as is necessary to preserve the stability of the trench and ensure the safety of
neighbouring structures and services.
In the event of a rapid loss of bentonite suspension from the excavation, backfill the excavation without
delay and inform the SO immediately. Obtain consent from the SO before resumption of the
excavation.
Remove support fluid wholly or partially and replace while maintaining the required fluid head if it does
not meet all requirements prior to concreting.
4.7
Cleanliness of the Base
Clean the base of the excavation of as much loose, disturbed and remoulded material to the satisfaction
of the SO prior to placing steel or concrete.
4.8
Spillage and Disposal
Take all reasonable steps to prevent the spillage of bentonite suspension on the site in areas outside
the immediate vicinity of boring. Remove discarded or contaminated bentonite from the Site without
delay. Dispose of the bentonite in compliance with the by-laws and regulations of the appropriate
authority.
4.9
Reinforcement
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4.9.1
Cages and minimum space requirements
Diaphragm wall cages are lowered in the trenches supported by slurry made of bentonite and to be
finally tremie concreted. Minimum clear spacing between vertical bars and horizontal bars in all
directions inside the cage must be provided. This aspect must be considered during the design in
order to achieve proper flow of tremie concrete and ensure no honeycomb is formed and quality of
concrete is not compromised. The clear spacing requirements shall comply with BS EN 1538, Clause
7.5.
4.9.2
Fixing
(a)
Keep the number of joints in the longitudinal bars to a minimum.
(b)
Arrange the joints such that the full strength of each bar is effective.
(c)
The reinforcement cages shall be sufficiently rigid to enable them to be handled, lifted, placed and
concreted without damage.
(d)
The reinforcement shall be adequately fixed to avoid damage and/or displacement during handling and
lifting operations.
(e)
Incorporate distance spacers of an accepted type, which shall be capable of resisting deformation during
cage placement within the trench and which shall not entrap slurry during concreting, in the cage
construction to maintain the minimum specified cover during concreting.
Ensure the location of lifting points and design of lifting lugs is acceptable to the SO. Take
special care to ensure adequate lapping length is provided for all the corner panels and
when there is more than 1 reinforcement cage within a single panel.
4.9.3
Welding
Welding shall be in accordance with BS ISO 17660-2 and BS EN ISO 17760-1. Do not use welding of
cold worked high tensile reinforcement bars as a method of splicing cages.
Welding of hot rolled high tensile steel bars shall be permitted provided a method is used which
shall not adversely affect the properties of the bars.
4.9.4
Marking
Mark the front and rear of cages following fabrication to identify them during placement.
Paint lifting points with contrasting colour from the main reinforcement for ease of identification.
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4.9.5
Placing
Lower the steel reinforcement accurately into position with sufficient spacer blocks to ensure the
correct cover is maintained at all times.
Check spacer blocks are of suitable durability.
Allow a vertical tolerance of ±50 mm on the level of the reinforcement projecting above the cut-off
level.
4.10
Concreting
Refer to the Section C03-010: Clause:4 and Section C03-020: Clause:4 for general concreting
requirements.
4.10.1
Placing Concrete
Engage a method of placing and the workability of the concrete such that a continuous monolithic
concrete panel of the full cross-section is formed.
Place the concrete without such interruption as would allow the workability of the previously placed
batch to have deteriorated significantly. Ensure the method of placing is accepted by the SO. If
necessary, incorporate an accepted set retarding additive into the mix in order to ensure extended
workability of the concrete after placement.
Take all precautions in the design of the mix and placing of the concrete to avoid arching of the concrete
in forming the diaphragm wall
Prevent contamination of the concrete by spoil, liquid or other foreign matter.
4.10.2
Workability of Concrete
Refer to Section C02-30-01: Clause:3.4 for workability of concrete. Slump measured at the time of
discharge into the diaphragm wall trench or at the time of discharge into the concrete pump hopper
shall be in accordance with the requirements stated in BS EN 1538, SS EN 206 and SS 544 Part 1
and SS 544 Part 2. Refer to SS EN 206, Annex D for specific diaphragm wall concrete. Also refer
to Section C02-030-01: Clause:3.4.3.
4.10.3
Compaction
Do not use internal vibrators to compact concrete in the wall panels as this will lead to segregation.
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4.10.4
Placing Concrete Under Water or Under Drilling Fluid
Place concrete under water or drilling fluid using a tremie concrete pipe. Do not engage alternative
methods of underwater placement such as the use of a drop bottom bucket or hose from a concrete
pump unless otherwise accepted.
Do not discharge concrete freely into the water or drilling fluid.
Before placing the concrete, propose a method that is acceptable to the SO, such that there is no
accumulation of silt or other material at the base of the trench or boring, and that heavily
contaminated drilling fluid suspension, which could impair the free flow of concrete from the pipe of the
tremie has not accumulated at the bottom of the trench or hole.
Take a sample of the drilling fluid suspension from the top and the base of the trench or boring using an
accepted sampling device. If the specific gravity of the suspension exceeds 1.15 or does not comply
in any respect with the stated limits for the particular material, do not proceed with the placing of
concrete. In this event, modify or replace the drilling fluid as agreed to meet the Specification.
4.10.4.1
Tremie Equipment
Check that the hopper and pipe of the tremie is clean and watertight throughout.
Extend the pipe to the base of the trench or boring and place a sliding plug or barrier in the pipe to
prevent direct contact between the first charge of concrete in the pipe of the tremie and the water or
drilling fluid. If the plug or barrier is sacrificial, do not retain it in the mass of the concrete.
4.10.4.2
Tremie Procedure
The tremie pipe after the initial pour shall at all times penetrate the concrete, which has previously
been placed with a maximum embedment of 6 m and a minimum embedment of 3 m, and shall not
be withdrawn from the concrete until completion of concreting. Develop a system of level checks for
the concrete and pipe outlet to ensure that this requirement is met.
At all times, maintain a sufficient quantity of concrete within the pipe to ensure that the pressure from it
exceeds that from the water or drilling fluid. The internal diameter of the tremie pipe shall be of sufficient
size to ensure easy flow of concrete.
The number of tremie pipes per panel is to be acceptable to the SO. Where more than one tremie
pipe is employed during concrete pouring to any one panel, arrange the charging of concrete in the
pipes so that the difference in concrete level at each pipe position is not greater than 250 mm. Confirm
this level by soundings taken during the concrete pour.
4.10.4.3
Delay in Concreting Operation
Should a delay or breakdown occur during the concreting operation, which in the opinion of the SO
could cause a cold joint, entrapment of laitance in the tremie concrete or otherwise lead to defective
concrete, abandon the concrete placing. Ensure that an adequate supply of concrete to the tremie is
available at all times so that placement is continuous.
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4.10.5
Finished Level
Cast concrete to such a level that only sound concrete remains below the cut-off levels.
Cut down concrete cast above the levels shown in the Drawings to within a tolerance of +0.1 m, -0.0
m.
If the cut-off level is more than 1 m below the top of the guide walls, bring the concrete to 0.5 m
above the cut-off level, ±150 mm.
4.11
Stop Ends
4.11.1
General
Check that stop ends, inserted before placement of concrete in the panel, are clean and have a
smooth regular surface. Ensure any shutter release agent is to the acceptance of the SO. Where
stop ends are inserted in sections, provide adequate joint connections to ensure verticality of the
complete tube.
4.11.2
Extraction
Carry out the extraction of stop ends at such a time and in such a manner as to avoid any damage to
the concrete placed against them, or to the adjacent soil and structures.
4.12
Joints
Where concrete is cast against previously completed wall panels, clean the previously formed concrete
so that solid substances are removed before the joint is formed.
When the diaphragm wall joint is exposed upon subsequent excavation, repair all joints that permit
jetting, spraying or water leakage.
4.13
Exposed Panels
Where diaphragm wall panels are exposed within the structure, thoroughly clean the exposed surface
to remove all traces of bentonite, soil, or other contaminating material so as to expose only sound
concrete material.
Apply this requirement irrespective of whether or not the exposed panel is to be subsequently covered
by in-situ concrete.
4.14
Tolerances
4.14.1
Setting Out
Establish all lines, levels and be responsible for the correct positions of all panels. Carry out setting out
from the main grid lines of the proposed structure. Immediately before installation of the diaphragm wall,
mark the element positions with suitable identifiable pins or markers.
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4.14.2
Construction Tolerances
The impact of construction tolerances for rebars, couplers and inserts must be considered in the
design of the diaphragm wall.
4.14.2.1
Distance Between Guide Walls
Achieve the following tolerances:
(a)
Minimum distance: the diaphragm wall thickness plus 25 mm
(b)
Maximum distance: the diaphragm wall thickness plus 50 mm
Prop the guide walls as necessary to maintain these tolerances during the course of construction of the
Works.
Check that the reference line, on the face of the guide wall towards the trench and on the side of the
trench nearest to the subsequent excavation, does not vary from a straight line or specified profile
by more than ±6 mm in any 5 m wall length and shall be maintained so that there is no abrupt
change.
4.14.2.2
Profile of Excavated Trench
Measure the profile of each excavated trench to check the trench dimensions as excavation proceeds
and to ensure the verticality of the trenching equipment meet the construction tolerance on verticality.
Submit records of dimensions of profile to the SO.
4.14.2.3
Exposed Wall Face
Achieve the verticality of the plane of the wall face to be exposed to within a tolerance of 1 in
200. Allow a further 75 mm horizontally for local protrusions beyond the wall face, resulting from
irregularities in the ground excavated.
4.14.2.4
Recesses and Inserts
Position recesses and inserts formed within the wall to the following horizontal and vertical tolerances:
4.14.2.5
(a)
Recesses located at a depth of up to 15 m below the top of the guide walls: ±100 mm
(b)
Recesses located at depths in excess of 15 m: ±150 mm
Positioning Reinforcement
Achieve the tolerances in positioning reinforcement as follows:
(a)
Longitudinal tolerance at cage head measured along trench: ±75 mm.
(b)
Vertical tolerance at cage head in relation to top of guide wall: ±50 mm.
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(c)
4.14.2.6
A minimum cover to reinforcement of 75 mm shall be maintained.
Block-outs
Position block-outs for penetrations, recesses and inserts formed within the walls within the tolerances
given in Section C02-030-01: Clause:4.14.2.4.
4.14.2.7
Remedial Measures
If during the general excavation, it is detected that the above stated tolerances have been
exceeded, submit proposals for remedying the defects for the acceptance of the SO. In addition,
the SO may require an amended method statement to be submitted for acceptance for further
construction of the diaphragm walls.
5
VERIFICATION AND SUBMISSIONS
5.1
Submissions
5.1.1
Method Statement
Prior to commencement of the Works, submit a method statement for the proposed method of installation
to achieve the required performance, including:
(a)
All details of proposed plant and trench excavation equipment
(b)
The sequence of excavation and concreting of panels
(c)
Dimensions and details of guide walls
(d)
Dimensions of walls and lengths of panels - the formation of joints between panels, method of installation of
waterstop between joints, the type, source, chemical and physical properties of the waterstop blade
between the joints and details of sealing joints to comply with Section C02-030-01:Clause:4.12.
(e)
Details and properties of support fluid - the mixing, transporting and placing equipment for the bentonite
slurry
(f)
The cleaning and reuse of bentonite slurry
(g)
The type, source, chemical and physical properties of the drilling fluid to be used.
(h)
Calculations to show that the density of the bentonite and lowest head of slurry are sufficient to maintain
the stability of the trench, in the ground conditions envisaged, to its entire length
(i)
The method of disposal of contaminated bentonite slurry
(j)
Method of handling and placing reinforcement cages
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5.1.1.1
(k)
Method of forming block-outs for penetrations, recesses, inserts, starter bars
(l)
Details of spacers to be used on reinforcement cage
(m)
Details of concrete and grout mixes and method of concreting and grouting
(n)
Details of specialists used for grouting
(o)
The method of monitoring and checking the tolerances associated with the diaphragm wall panels
(p)
The method used to check verticality of trench
(q)
The method of monitoring and checking the stability of the diaphragm wall trench
(r)
The method of monitoring and checking the stability of neighbouring properties, highways, services and
other underground structures
(s)
All details of proposed monitoring equipment - the names of the specialist land surveyor and
instrumentation contractors to be engaged
(t)
Programme for the Works, including details of the manpower and equipment to be employed
(u)
Staff organisation chart and curricula vitae of key personnel to be employed on the Works, indicating
whether they are to be part-time or full-time
Walls Designed to Support Vertical Loads
For walls which have been designed to support vertical loads, provide additional information as follows:
(a)
The method to overcome trench excavation in bearing stratum and founding level requirements.
(b)
Ultimate load tests with adequate instrumentation on individual bored piles or barrette piles to be conducted
to verify the foundation design parameters adopted for the diaphragm wall vertical load carrying capacity.
(c)
Shaft grouting if required to improve the skin friction characteristics, details such as grouting pipes, grids,
grouting pressure to be submitted through a method statement to the approval of the SO. The design
parameters shall be established through ultimate load tests or panels required to be socketed into rock,
the method to ensure the required rock socketing length, including additional site investigation to check the
rockhead quality by a minimum of 3.0 m coring below the founding level.
(d)
The method to clean the wall base.
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(e)
5.1.2
Base grouting at the bottom of the trench if required shall be supported by a method statement to the
approval of the SO. Parameters such as limiting grouting pressure and grouting volume shall be clearly
stated in the method statement and the construction drawing.
Shop Drawings
Submit shop drawings of the diaphragm walls and related works for the acceptance of the SO prior to
the commencement of works. The drawings shall include the following:
5.1.3
(a)
Layout of diaphragm walls, and guide walls with suitable survey co-ordinates and dimensions
(b)
Sequence of construction of wall panels, including relevant sections
(c)
Details of stop ends, including details of waterproofing with water stops or other proprietary products
(d)
Reinforcement details of wall panels, including spacers, steel bracing, etc.
(e)
Sizes and locations of block-outs for penetrations, recess, inserts, starter bars, etc.
Verification of Bentonite
Provide a certificate from the manufacturer of the bentonite powder, showing the properties of each
consignment delivered to the Site.
Take samples so that at least one test is carried out for every 100 tonnes of bentonite supplied. Carry out
tests to provide the following information:
5.1.4
(a)
Apparent viscosity and gel strength of a suspension of bentonite in water
(b)
Moisture content of the bentonite powder and wet screen residue on US 200 mesh sieve
(c)
A statement of the conditions of test, such as water analysis, mixer type, mixer speed during testing, time
of stirring and time of testing after initial addition of bentonite to the water
Bentonite Mixing Equipment
Submit a suitable design of hopper cone and bentonite feeding device for acceptance by the SO.
5.1.5
Quality Control Plan
Prepare and submit the quality control plan for SOs acceptance prior to starting work.
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5.2
Testing
For applicable testing and frequency of tests, follow EFFC/DFI, Guide to Support Fluids for Deep
Foundations, as shown below:
Table 3. Applicable tests and minimum frequency for bentonite support fluids
Test method
Fresh fluid
Excavation fluid
Before
concreting
Frequency
.
daily
Once per element
Before pour
daily
Viscosity
Marsh funnel
M
R
M
M
Density
Mud balance
M
R
M
M
Sand content
Sand content
kit
N/A
R
M
R
pH
pH paper
M
R
M
R
Filter loss
API
press
filter
M
R
M
M
Filter cake thickness
API
press
filter
M
R
M
M
Silt content
Calculation
N/A
N/A
O
O
Gel strength
Fan viscometer
O
N/A
O
O
Test
Fluid for reuse
M: Mandatory, R: Recommended, O: Optional, N/A: Not Applicable
5.2.1
Compliance Testing of Support Fluid
5.2.1.1
Frequency of Testing
Propose the frequency of testing drilling fluid, and the method and procedure of sampling prior to the
commencement of the Work. The frequency may subsequently be varied as required, depending
on the consistency of the results obtained.
Measure density, Marsh viscosity, pH, filtrate and cake of freshly mixed support fluid, daily, as a check
on the quality of the suspension being formed. Calibrate the measuring device to read to with 0.01 g/ml.
5.2.1.2
Batch Testing
Carry out tests to determine the density, viscosity, filtrate, cake and pH value to each batch of freshly
mixed or reconditioned bentonite supplied to the Works and submit the results before the batch is used
in excavations. For average soil conditions, the results shall generally comply with BS EN 1538,
Tables 1 and 2. Carry out the tests until a consistent working pattern has been established, taking
account of the mixing process, any blending of freshly mixed bentonite suspension and previously
used bentonite suspension and any process which may be used to remove impurities from previously
used bentonite suspension.
Shear strength test and range values shall be specified when ground conditions are such that support
fluid loss and penetration can affect trench stability. Refer to DIN 4126.
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5.2.1.3
Alternative drilling fluid
For testing drilling fluid in lieu of bentonite, test in accordance with API-RP-13B-1 unless otherwise
agreed or directed by the SO.
5.2.1.4
Testing from Excavation
Take at least 1 sample of fluid from the base of the excavation and 1 from the top, immediately prior to
placing reinforcement and concrete. Comply with values recommended in BS EN 1538, Table 2 for
bentonite.
5.2.1.5
Limits Prior to Concreting
Measure the density, viscosity together with sand content and filter press determinations from a sample
taken at the base of the trench immediately before concreting. Ensure conformance to BS EN 1538,
Table 2. Take a full range of tests when additional wall support materials, e.g. polymer are added to
the slurry.
Change the slurry, as directed by the SO, if a sample obtained from near the bottom of the trench
indicates possibility of undue contamination by the bentonite.
5.2.1.6
Testing Laboratory
Establish a suitably equipped and maintained site laboratory for testing the support fluid. Provide
skilled staff and all necessary apparatus to carry out the sampling and testing.
5.2.1.7
Equipment
Ensure the test equipment employed comply with accepted standards. Additional or alternative
equipment may be employed with the acceptance of the SO.
5.2.1.8
Rate of Sampling
Obtain samples from the panel during excavation and allow for one sampling per 5 m depth or per each
change of soil type as determined by the SO.
5.2.1.9
Monitoring pH Levels
Monitor the pH values when additives are added.
5.2.1.10
Alternative Materials
Test alternative materials in lieu of bentonite where appropriate, or propose alternative tests to
demonstrate the required properties. Ensure that storage conditions are as recommended by the
supplier of the material.
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5.2.2
Concrete Cube Testing
Refer to the Section C03-010: Clause:5.1 for concrete cube testing requirements. Take
test cubes for each panel constructed.
Check that cubes have the same marks as the wall panel numbers and are sub-marked within each
panel set.
5.3
Verification of Load Carrying Capacity
Carry out load testing to verify the structural and geotechnical load carrying capacity of diaphragm walls
if the wall panels are used as piles or deep foundations.
Refer to Section C04-030: Clause:4.3, for details of pile test requirements.
5.4
Records and Reports
5.4.1
Records
Keep the following records for each wall panel and make such records available for inspection by the
SO within 24 hours of the completion of each panel.
(a)
Panel Number
(b)
Date and time of start and of finish of panel excavation
(c)
Details of any obstructions encountered and the time spent in dealing with obstructions
(d)
A log of soil type encountered from start to finish of excavation and water levels
(e)
Date, place and time of slurry control tests and results recorded
(f)
Quantity of slurry removed from site and spoil removed from site recorded by date
(g)
The trench verticality and profile of panel
(h)
Length of panel and width and depth of panel from top of guide wall level
(i)
Date and time of completion of cage placement. Details of cage type for reinforcement
(j)
Date and time of start and of completion of panel concreting
(k)
A graph of theoretical and placed concrete volumes with depth
(l)
Volume of concrete used and time of any interruptions recorded in concrete supply where these exceed 15
minutes. Volumes of normal and lean mix concrete
(m)
Cut-off level of concrete below top of guide wall level
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(n)
5.4.2
Concrete test cubes, markings, date and results obtained on testing
Grouting Records
Provide duplicate records within 24 hours of completion of grouting, showing the following:
5.4.3
(a)
Panel identification
(b)
Date
(c)
Leakage test
(d)
Records of pressure and uplift
(e)
Total uplift
(f)
Grout test results
As-Built Drawings
Keep and submit accurate records of the actual Works constructed. For those parts of the Works
which will become hidden by further progress, check and verify such records while those parts of
the Works are open for inspection.
All drawings submitted are to have relevant particulars at the bottom right-hand corner, including the
project title, Contractor's name, title of drawing, scale, date, drawing number and notes identifying
revisions made. Other details to be included in the as-built drawings are as follows:
(a)
Diaphragm wall layout plan showing the panel size and the actual positions and eccentricities in
perpendicular directions of the diaphragm walls at ground level.
(b)
Elevation view of the length of panel installed from cut-off level to toe of panel associated with the soil
stratum and water level encountered. Cut-off level for each panel shall be expressed as reduced levels.
(c)
Reinforcement details of installed panels and capping beams where relevant, and grade of concrete used.
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(7) C02-030-02 Sheet Pilling
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1
GENERAL
Read this Section with G01-010 "General Requirements" and all other contract documents.
1.1
Scope
This Section covers requirements for construction or installation of sheet piling as an embedded
retaining wall type to resist principally horizontal loads, or also to support vertical loads.
Other types of embedded retaining walls are covered under the following sections: C02030-01 Diaphragm Wall
C02-030-03 Contiguous Bored Pile Walls and Secant Pile Walls
1.2
Related Sections
Read this Section in conjunction with the relevant requirements of the following sections:
1.3
C01-020
Condition Survey
C02-010
Ground Investigation
C02-020
General Earthworks (Excavation and Filling)
C02-050
Instrumentation and Monitoring
C05-010
Structural Steelwork
C05-020
Protective Works for Structural Steelwork
Standards, Codes, Regulations and Technical References
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1.3.1
Standards and Codes
Unless otherwise agreed by the SO, ensure all of the Works comply with the relevant requirements of
the standards and codes listed below or referenced in the body of the Specification. Alternative
standards and codes may be proposed for approval by the SO, provided it can be demonstrated that
the alternative standards and codes comply with the requirements of the standards specified. All
standards and codes quoted are the current version, unless specific year references are noted.
In the event that the standards or codes are partially superseded or have become obsolete, refer
to the current edition or the approved substitution for the relevant clauses.
Singapore Standards
SS EN 1993
Eurocode 3 - Design of steel structures - Part 5:Piling
NA to SS EN 1993 - 5
Singapore National Annex to Eurocode 3 - Design of steel structures Piling
SS EN 1997
Eurocode 7: Geotechnical Design - Part 1: General Rules Eurocode
7: Geotechnical Design - Part 2: Ground Investigation and Testing
NA to SS EN 1997 - 1
Singapore National Annex to Eurocode 7: Geotechnical design General rules
NA to SS EN 1997 - 2
Singapore National Annex to Eurocode 7: Geotechnical design Ground investigation and testing
.
.
Other Standards
BS EN 12063
1.3.2
Execution of special geotechnical works. Sheet pile walls.
BS EN 12699
Execution of special geotechnical works. Displacement piles.
BS EN 10025
Hot rolled products of structural steels.
BS EN 1011-1
Welding - Recommendations for welding of metallic materials - Part 1:
General guidance for arc welding
BS EN 1011-2
Welding - Recommendations for welding of metallic materials - Part 3:
Arc welding of ferritic steels
BS EN ISO 9606-1
Qualification testing of weldersFusion weldingPart 1:Steels
BS EN ISO 2409
Paints and varnishes - Cross-cut test
BS 5228
Code of practice for noise and vibration control on construction and
open sites - Part 1: Noise
Code of practice for noise and vibration control on construction and
open sites - Part 2: Vibration
BS 7079
Part A1: Surface Finish of Blast Cleaned Steel for Painting and Steel
Structures
Technical References
Refer to the following technical reference for guidance in carrying out the Works.
(a)
LTA Code of practice for Railway Protection (2004)
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(b)
LTA Guide to carrying out restricted activities within Railway Protection and Safety Zones (2009)
(c)
LTA Guide to carrying out engineering works within road structure safety zone and engineering activity on
land adjoining public streets (2011)
(d)
BCA BC1: 2012 Design guide on use of alternative structural steel to BS 5950 and Eurocode 3
(e)
BRE Digest 251 Assessment of damage in low-rise buildings
(f)
CIRIA Report C580 (2003) Embedded Retaining Walls - guidance for economic design
(g)
CIRIA Report C760 (2017) Guidance on embedded retaining wall design
1.4
Trade
Preamble
Not
In Use
S1.4.14
Safety
Provide safety precautions to comply with all current legislation and regulations, notably: Building
Control Regulations
Code of Practice for Traffic Control at Work Zone
Factories (Building Operations and Works of Engineering Construction) Regulations Factories
Act
SS CP 79 Safety management system for construction worksites
For works within LTA Railway Protection Zone, ensure the works comply fully with Code of Practice for Railway
Protection.
Additionally, comply also with the following:
BRE Digest 251 (1995) Assessment of damage in low rise building
BS 8008: Guide to safety precautions and procedures for the construction and descent of machine-bored shaft for
piling and other purposes
1.4.1
Development of Design Requirements
The notional design of the sheet pile wall works is indicated in the drawings. The lateral support of
strutting or ground anchor system indicated in terms of the installation levels, the required stiffness and
preloading, are provided schematically where applicable. Based on the information provided,
undertake and provide for the SOs acceptance the following which shall be carried out by appropriately
qualified, competent and experienced personnel and PE:
(a)
Design or construction verification checks based on site and actual ground conditions to confirm the
required penetration length, type of sheet pile and sizes of all temporary or permanent strutting elements
and wailings for the sheet pile walls.
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(b)
Prepare a response plan in the event that the temporary or permanent sheet piled wall and strutting
elements do not perform as expected in the design in controlling the sheet piled wall deflection, and in the
event that measures taken to control ground movement and vibration do not perform satisfactorily.
Establish and indicate the alert levels and work suspension levels for forces and deflection of the sheet
piled wall on the drawings. The response plan shall be feasible for timely implementation with due
consideration of the construction sequence and site restraints.
(c)
Prepare and submit all design and construction sequence, including drawings and reviews that shall be
endorsed by appropriately qualified, competent and experienced PE where applicable, to the SO for his
acceptance. The same submission shall be made to relevant authorities where applicable.
Submit the curriculum vitae (CV) of the personnel and specialists where applicable to the SO for
acceptance.
1.4.2
Layout Drawings
Engage qualified and experienced personnel to prepare co-ordinated layout drawings for the sheet pile
wall panels.
Submit the drawings to the SO for acceptance prior to commencing the installation works.
1.4.3
Supervision of the Works
Engage a competent and suitably experienced site engineer with the SOs acceptance, to supervise the
field works. The supervision requirements shall be in accordance with BCA requirement depending on
the size of the project.
Site Supervision Plan for supervising the structural and geotechnical building works shall be prepared
and submitted by qualified, competent and experienced PEs to the relevant authorities and in
accordance with the current guidelines issued under the Building Control Act and Regulations.
1.4.4
Quality Control Plan
Submit and work to a quality control plan as agreed with the SO. Refer Section G01- 010:Clause:1.4.7.
1.4.5
Welders' Qualifications
Engage only certified welders who are qualified in the accepted welding procedure in accordance with
BS EN ISO 9606-1 and have a proven record over the previous 6 months, or who have attained an
equivalent standard, on the Works. Provide certificates relating to welders' tests to the SO on
request.
S1.4.6
Coordination with Other Works
Co-ordinate with other contractors who may carry out other works at the same time at the site. Take into
account of site access, space occupation, safety and safeguarding of adjoining properties and each
other’s works
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S1.4.7
Condition Survey
Where applicable, prior to and upon completion of the site works, carry out a condition survey to adjacent buildings in
accordance with the requirements of section C1-20 “Condition Survey and Monitoring”. Submit all records to the SO and
adjacent property owners where directed.
Keep a copy of the survey report on site ready for inspection.
S1.4.8
Instrumentation and Monitoring
Provide instrumentation to monitor the ground movement, vibration and condition of adjacent properties. Refer to
Section C2-50, Clause 3.1, and the drawings for the schedule of instrumentation required. If necessary or as
required by the authorities, propose and provide additional instrumentation and monitoring for records.
Take cognisance of and co-ordinate with other contractors on site who may be carrying out instrumentation and
monitoring works to avoid duplication of installation and readings.
For general requirements of the instrumentation and monitoring works refer to Section C2-50.
S1.4.9
Upholding of Adjoining Properties
Accept responsibility for the upholding of the adjoining buildings and roads, footpaths etc., where applicable, together
with the mains and services from the time of taking possession of the site through the duration of the works.
Adequately maintain roads and footpaths within and adjacent to the site and keep clear of mud and debris.
S1.4.10
Verification of Site Information
Verify and be satisfied that the information given in the existing site survey plans provided are accurate. If necessary,
engage a registered Surveyor to carry out additional site survey before commencing any work.
Carry out additional ground investigation where additional information is needed for the works or when directed
by the SO. Carry out the works in compliance with Section C2-10 “Site investigation”.
Carry out the boreholes progressively prior to commencement of the works in areas according to the
contractor’s construction programme. On completion of drilling, backfill the boreholes with a suitable
bentonite/cement mix.
Submit the location and schedule for the boreholes to SO’s acceptance prior to carrying out the works. On completion,
prepare the site investigation report and submit to the SO for acceptance.
S1.4.11
Existing Services Affected by Works
Refer to Preliminaries and conditions of contract for the requirements to deal with existing services affected by the
works.
S1.4.12
Site Protection
Protect all equipment and working area using fencing or other methods as accepted.
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S1.4.13
Obstructions
If any obstructions such as existing fences, structures, footings, boulders, concrete blocks, pipes, drains, driveways or
ramp are encountered during excavation, submit proposals for their removal for the SO's acceptance.
2
PERFORMANCE REQUIREMENTS
2.1
Pile Embedment for Load Bearing
For sheet pile walls that are also used for vertical load bearing purposes, verify the required
embedment length, taking into account the actual ground conditions and the results of load tests of
preliminary elements or production piles in accordance with SS EN 1997.
2.2
Penetration Depth
Drive the sheet piles to a depth as shown in the drawings or when practical refusal as follows is met if
earlier:
(a)
Not In Use
S(a)
Under continuous vibrating: the rate of penetration <=100 mm/min
(b)
Not In Use
S(b)
Under driving: the sheet pile penetration <= 25 mm per 10 blows
If practical refusal is met earlier than the stipulated depth, carry out review and design verification as in
C02-030-02:Clause:1.4.1 and report to the SO.
2.3
Driving Assistance
Any driving assistance such as pre-boring, water-jetting, crush piler or preblasting shall be planned and be
approved by the SO prior to start of work, taking into consideration of the influence of driving assistance
methods on the performance of the piles and safety of existing structures or potentially unstable slopes.
2.4
Water Retention
Fully interlock all clutches and close all corners. Specially fabricate the corner sheet piles to prevent
declutching and water leakage. Particular care should be observed when driving sheet piles through hard
strata to prevent damage and de-clutching, and check that installation in the actual ground is in
accordance with the design.
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S2.5
Permissible Damage Criteria for Existing Critical Structures or Services
Based on the results of the damage assessment as set out in Clause 1.4.2, propose the allowable wall
deflection, ground settlement and vibration limits due to the works taking into account the vulnerability and
sensitivity of the adjacent properties.
State the values for alert and work suspension levels in the submission in accordance with the requirements of
Building Control Act [Section 7(2)] Annex (BE/CP/5 OCT 2001).
Notwithstanding the above, ensure that the ground movements and vibrations generated by the works comply
with the following if more stringent:
Generally comply with the requirements of BS 5228 Part 1.
The vibration generated by the works in MRT structures not to exceed a peak particle velocity of 15mm/s.
Unless otherwise directed, refer to Section C2-50, Clause 4.2.2 for general restrictions on ground movements and
vibration limits for adjacent structures where relevant.
3
MATERIALS
3.1
Steel Grade
All steel for sheet piles shall be manufactured to BS EN 10248 or BS EN 10025 and to the
grade as specified or indicated in the drawings with minimum steel grade S275.
[Note 1: Select S270 GP or S355 GP as appropriate.]
The sources of supply of materials shall not be changed until the Contractor has demonstrated that the
materials from the new source can meet all the requirements of the specifications.
Materials failing to comply with specifications shall be removed promptly from the Site.
3.2
Durability and Protection
3.2.1
Sheet Pile Coating
Propose and provide suitable coating protection based on soil exposure conditions. Anti-rust coatings
such as bitumen/primer are flammable in liquid state. Hence, coating works shall be carried out away
from ignitable sources.
3.2.2
Specialist Labour
The preparation of surfaces and the application of the coats to form the coating shall be carried out by
specialist labour with experience in preparation of the surface and in application of the coating
specified.
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3.2.3
Surface Preparation for Coating
All surfaces to be coated shall be clean and dry, and prepared by one or both of the following methods, as
specified.
Carry out degreasing with detergent wash compatible with the coating, where necessary.
All surfaces shall be blast cleaned to Sa 2.5 of BS 7079, Part A1. Carry out blast-cleaning after
fabrication. Unless an instantaneous-recovery blasting machine is used, the cleaned steel surface
shall be air-blasted with clean dry air and vacuum-cleaned or otherwise freed from abrasive
residues and dust immediately after cleaning.
3.2.4
Application and Type of Primer
Within 4 hours after surface preparation, before visible deterioration takes place, coat the surface with
an appropriate primer or the specified coating. Do not apply coating to a metal surface which is not
thoroughly dry.
3.2.5
Control of Humidity during Coating
Do not apply coating when the surface metal temperature is less than 3°C above the dewpoint
temperature or when humidity could have an adverse effect on the coat. When heating or
ventilation is used to secure suitable conditions to allow coating to proceed, take care to ensure the
heating or ventilation of a local surface does not have an adverse effect on adjacent surfaces or
work already done.
3.2.6
Parts to be Welded
Apply the coating within 200 mm of a weld after welding. The method of application shall comply
with the manufacturer’s recommendations.
3.2.7
Thickness, Number and Colour of Coats
The nominal thickness of the finished coating and if necessary, of each coat shall be as specified or
shown in the drawings. The average coat or finished coating thickness shall be equal to or greater than
the specified nominal thickness. In no case shall any coat or finished coating be less than 75% of the
nominal thickness. Apply each coat after an interval that ensures the proper hardening or curing of the
previous coat.
Where more than one coat is applied to a surface, each coat shall, if possible, be of a different colour
from the previous coat. The colour sequence and final coating colour shall be documented.
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3.2.8
Inspection of Coatings
The finished coating shall be generally smooth, of dense and uniform texture and free from sharp
protuberances or pinholes. Excessive sags, dimpling or curtaining shall be re-treated.
Any coat damaged by subsequent processes or which has deteriorated to an extent such that proper
adhesion of the coating is in doubt shall be removed, and the surface shall be cleaned to the original
standard and recoated to provide the specified number of coats.
Check the completed coating for thickness by a magnetic thickness gauge. Areas where the thickness is
less than that specified shall receive additional treatment.
Check the completed coating for adhesion by means of an adhesion test to BS EN ISO 2409, carried
out on 10% of the piles. The adhesion of any completed coating shall not be worse than classification 2.
Do not carry out adhesion tests until 7 days after coating. On completion of testing, the test area shall
be made good to the standard specified in the particular specification. Areas where the adhesion is
defective shall be repaired and re-inspected.
3.3
Fabricated Sheet Piles
Fabricate and supply all sheet piles to the manufacturer’s recommendations.
Unless otherwise approved by the SO, all steel sheet piles shall be within the dimensional tolerances as
shown in Table 1.
Table 1. Dimensional tolerances for steel sheet piles
Dimension to which tolerance applies
3.4
Tolerance
1. Width
(a) Single piles (b)Interlocked
piles
2%
3%
2. Thickness of section
5%
3. Weight
5%
4. Length
50mm
5. Squareness of cut for each section
(a) parallel to line of wall (b)perpendicular to
line of wall
2%
10mm
6. Straightness
0.2% of pile length
7. Depth of section
4%
Clutch Sealant
Unless otherwise specified in the drawings, propose suitable clutch sealant to SOs acceptance.
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3.5
Installation Equipment
Satisfy the SO regarding the suitability, efficiency and energy of the installation equipment that shall be in
accordance BS EN 12063.
Where a drop hammer is used, the mass of the hammer shall not be less than half that of the sheet
pile self-weight. For other types of hammer the energy delivered to the sheet pile shall be at least
equivalent to a drop hammer of the stated mass.
3.6
Reuse of Sheet Piles
Do not reuse sheet piles installed previously unless all specified requirements are demonstrated to be
met and subject to the SOs approval. The thickness of the sheet pile shall be re-measured and
recorded. Assess the available ultimate bending moment and shear capacity considering corrosion
effects.
All reuse sheet piles, if accepted by the SO, shall comply with BC1: 2012 Design guide on use of
alternative structural steel to BS 5950 and SS EN 1993.
4
WORKMANSHIP
4.1
General
Ensure the equipment set up, installation procedures and execution conform with BS EN 12063 and BS
EN 12699 as applicable.
[Note 1: BS EN 12063 is being reviewed to cover the execution of permanent or temporary sheet pile
wall, combined pile walls, high modulus walls structures and the handling of equipment and materials.
It applies to steel sheet pile walls, combined walls, high modulus walls, synthetic sheet pile walls
(composite), precast concrete and timber sheet pile walls.]
4.2
Marking and Storage
4.2.1
Marking
Mark each sheet pile with the grade accorded.
4.2.2
Storage
Store sheet piles of different grades separately. Place of storage shall be safe from theft. Refer to
BS EN 12063.
4.3
Clutch Sealant
Apply in accordance with the manufacturer’s recommendations and in accordance to BS EN 12063.
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4.4
Handling and Installation
4.4.1
Handling
Ensure the interlocks are clean and undistorted.
Avoid any significant damage to the sheet piles and coatings during all lifting, handling and pitching
operations.
Refer to BS EN 12063 on handling of equipment and materials.
4.4.2
Installation
The execution of the sheet pile wall shall be in accordance to BS EN 12063.
4.5
(a)
Select plant to suit the ground conditions and type of sheet pile. Submit details for the SOs acceptance.
(b)
Provide at least 24 hours’ notice to the SO prior to the commencement of installation.
(c)
Guide all sheet piles and hold in position with temporary gates. Ensure all sheet piles are properly
interlocked.
(d)
Provide adequate support and restraint to the free length of sheet pile at all stages during the installation
process.
(e)
Install the end sheet piles in advance of the intermediate sheet piles. Avoid excessive lead of the end
sheet piles ahead of the general panel level.
(f)
Position the sheet pile installation equipment to align with the axis of the sheet pile within the erection and
installation tolerances.
(g)
Install sheet piles to the specified level or level of resistance.
(h)
When pile installation encounters difficulties or hard or unexpected ground conditions, cease installation at
practical refusal or cease if the sheet pile is visibly damaged, and report to the SO.
(i)
Where the sheet pile has not reached the specified level, investigate, review and propose to the SO on
measures and methods to meet the design requirements as appropriate.
Jetting
Where jetting is used to assist sheet pile installation ensure that this does not affect the following:
(a)
The performance of the sheet piles
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(b)
The stability of surrounding structures
Refer to BS EN 12699 on needs for driving assistance.
4.6
Length of Sheet Piles
Sheet piles may be supplied in more than one length with the following provisions for the joints:
4.7
(a)
Locate splices away from positions of maximum stress.
(b)
Design spliced joints for full stresses imposed due to bending, shear and bearing.
(c)
Do not weld interlocks where sheet piles are spliced by butt-welding unless a sealing weld is required.
Splicing of Sheet Piles
Spliced joints shall be designed to cater for the combined effects of bearing, shear and bending stresses
imposed upon the sheet piles.
Sheet pile splicing in the form of full butt weld or steel plate with fillet weld shall have similar strength as
parent sheet pile. Allow minimum cooling time of 30 minutes for welds before continuing the installation
works.
Weld metal shall not encroach into the interlock area so as not to affect the capacity and interlocking
mechanism of the sheet piles.
4.8
Corrosion of Sheet Piles
Unless otherwise agreed by the SO, provide sheet piles with a sheet pile corrosion rate of not more than
0.015 m/side/year during the service life span in harsh environment.
4.9
Forming Holes in Sheet Piles
Do not burn holes without the approval of the SO. Drill holes in the sheet piles for ties and attachment of
walings, etc. after installation.
Drill or burnt all holes using a template, and dress flush subsequently. Check that the hole size is of
sufficient clearance and include allowance for bolt/tie coatings and inclination if not horizontal. Seal all
holes not required in the finished works by welding a plate of the same grade, of thickness not less
than the pan thickness to the pile. The minimum plate overlap is 40 mm and the minimum continuous
filet weld is 6 mm. All holes shall be within a positional tolerance of ±10 mm.
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4.10
Cutting and Welding
Do not carry out cutting or welding of sheet piles without prior approval from the SO. Carry out all such
cutting by means of oxyacetylene, oxypropane or the other approved method. The remaining pile
shall be of clean and even appearance with grinding tools being employed to remove splatter. Mark
cut offs for clear and easy identification with the source and dispose in the pre-agreed manner.
Carry out cutting in such a way as to prevent damage or distortion to adjacent piles. The finished level
of the cut pile shall be within 20 mm of the theoretical level. Allow a minimum cooling time of 30 minutes
for welds before continuing the installation work.
Carry out welding in accordance with procedures and recommendations specified in BS EN 1011-1
and BS EN 1011-2. Cut out and replace any defective welds.
For structural welds, refer also to BS EN 12699.
4.11
Walings and Tie Rods
Secure wailings to each pair of pile with anchor bolts, washers and bearing plates. All splices, if welded
or bolted, shall be at the fifth spacing between tie rods and splices in wailings and shall be staggered by
a minimum distance of 5 m.
Do not weld the tie rods or use for earthing purposes. Protect tie rods against welding splash. Assemble
tie rods with necessary taper washers, washers and bearing plates in accordance with the
manufacturer’s recommendations.
Take precautions during installation of the tie rods to avoid the following:
(a)
Deflection of the tie
(b)
Local bending of tie rod on wailing
(c)
Damage to the tie or protective coating of the tie
Tension the ties by means of a turnbuckle only and agree on the phasing of the tensioning with the SO
in advance. Take care to avoid damage to the tie rods during subsequent operations such as
backfilling. Submit procedure to accomplish this for the SOs acceptance. Where settlement is
expected to occur, place the ties inside a tube such that the tube settles with the ground but the tie
remains in the correct position.
4.12
Steel Sheet Piles and Installation Tolerances
Base the sheet pile line on nominal sheet pile size.
In addition to dimensional tolerances shown in Table 1 Section C02-030-02:Clause:3.3, install sheet pile
within the following tolerances:
(a)
Deviation perpendicular to theoretical line, ±50 mm
(b)
Deviation of verticality normal to and along the line of the sheet piles, 1:75
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(c)
Top of finished sheet pile level, ±50mm
5
VERIFICATION AND SUBMISSIONS
5.1
Submissions
5.1.1
Method Statement
Prior to commencement of sheet piling works, submit the following for the SOs acceptance for the
proposed method of installation to achieve the required performance:
5.1.2
(a)
Method of achieving penetration to depth as specified, including methods of dealing with obstructions
(b)
Proposals to mitigate noise and vibration, and an assessment of vibration characteristics for with piling
operations or activities
(c)
Details on the plant and equipment proposed for the installation of the sheet piles
(d)
Details of method of location and avoidance of critical services
(e)
Proposed methods for control of the sheet piling works, including the setting out and description of the
alignment controls, including the proposed methods for controlling the verticality and the rotation about
longitudinal centreline of the sheet pile
(f)
Method of checking the verticality and corrective actions to be taken if the deviation exceeds the maximum
permitted limits
(g)
All details of proposed monitoring equipment
(h)
Details of inserts for segmental sheet pile and details of clutch sealant proposed
(i)
Details of a quality control for the Site Works
(j)
Typical sheet pile record sheets
Shop Drawings
Submit shop drawings of the sheet pile works for the acceptance of the SO prior to the commencement of
Works, where applicable.
5.1.3
Work Programme
Submit work programme indicating the anticipated time required for installation of the sheet piles in the
overall work programme.
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5.1.4
Ground Investigation
Confirm that the ground investigation information provided is adequate for the sheet piling works and
design verification. Raise any concerns as to adequacy to the SO. Report immediately and without
delay to the SO any circumstance which indicates that in the Contractor’s opinion, the ground
conditions differ from those reported in or which could have been inferred from the subsurface
investigation reports.
5.1.5
Test Certificates
Provide the SO with test certificates accompanied by information on material analysis and mill sheets
where applicable.
5.1.6
Welding Procedures
Submit for acceptance full details of the welding procedures and electrodes with drawings and
schedules as may be necessary. Submit relevant documents for the qualified welders as stated in
Section C02-030-02:Clause:1.4.5.
Ensure that during the course of the work, displacement or damage which could impair either
performance or durability does not occur to completed elements.
5.1.7
Quality Control Plan
Prepare and submit the quality control plan for SOs acceptance prior to starting work.
S5.1.8
Monitoring of Adjacent Structures
Provide proposals for surveys and monitoring of movement and vibration in adjacent structures and services before work
commences and during the course of the works.
Submit the assessment of the effect of wall deflection and ground settlement to adjacent properties and the proposed
control limits.
5.2
Inspection and Testing
5.2.1
Inspection
Allow the SO to inspect and test at any stage of fabrication.
Ensure that adequate notice is given to the SO when fabrication processes can be inspected or tests can
be witnessed.
5.2.2
Weld Testing
Refer to Section C05-010 "Structural Steelwork" for general requirement on welding tests. Carry
out welding tests as specified or indicated in the drawings or as directed by the SO.
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S5.2.3
Radiograph of Welds
The acceptance standard for radiographs of sheet pile welds to be in accordance with BS PD 5500.
5.3
Records and Reports
5.3.1
Sheet Piling Records
Provide record sheets with the following information and submit 2 copies of these records to the SO
within agreed time frame after the sheet pile is installed.
(a)
Sheet pile reference
(b)
Sheet pile type and steel grade
(c)
Overall sheet pile length
(d)
Length of individual sheet pile sections
(e)
Details of joints
(f)
Type of hammer, if relevant
(g)
Date of installation
(h)
Commencing surface level and final toe level
(i)
Top level and bottom level of the sheet pile
(j)
Working level and type of construction plant
(k)
The number of blows to drive each 250 mm over the last 2.5 m shall be recorded, if relevant
(l)
All information regarding unexpected installation conditions such as in terms of increased penetration rates
or installation problems with the actual site or ground conditions and other interruptions or stoppages to the
sequence of work
(m)
Where changes in the pile length have occurred due to lengthening or cutting, all relevant information,
including off-cut length or extension length and reason for such change shall be included.
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5.3.2
As-Built Drawings
Unless otherwise agreed, submit as-built drawings of the sheet piling works for records. Keep accurate
records of the actual Works constructed. For those parts of the Works which will become hidden by
further progress, check and verify such records by the SO while those parts of the Works are open for
inspection.
All drawings submitted shall have relevant particulars at the bottom right-hand corner, including the
project title, Contractor's name, title of drawing, scale, date, drawing number and notes identifying
revisions made. Other details to be included in the as-built drawings are as follows:
5.3.3
(a)
Layout plan of the sheet piles showing the actual positions and eccentricities in perpendicular directions of
the sheets at ground level.
(b)
Elevation view of the installed sheets from cut-off level to toe. Express cut-off level in terms of Reduced
Levels.
Order of Piles
Ensure that the piles are available at the time for incorporation in the Works. All piles and production
facilities shall be made available for inspection at any time. Only new piles shall be used for
permanent works. Piles shall be carefully examined at the time of delivery and damaged piles
repaired or replaced. The records of testing of the steel used in the piles shall be submitted prior to
commencing the Works.
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(8) C02-030-03 Contiguous Bored Pile Walls and Secant Pile Walls
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1
GENERAL
Read this Section with G01-010 "General Requirements" and all other contract documents.
1.1
Scope
This Section covers the requirements for the construction and installation of contiguous bored pile walls
and secant pile walls as an embedded retaining wall type. Other types of embedded retaining walls are
covered in:
C02-030-01 Diaphragm Walls
C02-030-02 Sheet Piling
The walls may be temporary or permanent and used solely to form embedded retaining walls resisting
principally horizontal loads, or also to support vertical loads.
1.2
Related Sections
Read this Section in conjunction with the relevant requirements of the following sections:
C01-020
Condition Survey
C02-010
Ground Investigation
C02-050
Instrumentation and Monitoring
C04-010
Bored Piling Works
C04-030
Pile Testing
C03-010
Concrete Construction Generally
C03-020
Reinforcement
1.3
Standards, Codes, Regulations and Technical References
1.3.1
Standards and Codes
Unless otherwise agreed by the SO, ensure all of the Works comply with the relevant requirements of
the standards and codes listed below or referenced in the body of the Specification. Alternative
standards and codes may be proposed for approval by the SO, provided it can be demonstrated that
the alternative standards and codes comply with the requirements of the standards specified. All
standards and codes quoted are the current version, unless specific year references are noted.
In the event that the standards or codes are partially superseded or have become obsolete, refer
to the current edition or the approved substitution for the relevant clauses.
Singapore Standards
SS EN 1990
Eurocode: Basis of structural design
SS EN 1992-1-1
Eurocode 2: Design of concrete structures
- Part 1-1: General rules and rules for buildings
SS EN 1993-1-1
Eurocode 3: Design of steel structures
- Part 1-1: General rules and rules for buildings
SS EN 1997
Eurocode 7: Geotechnical Design - Part 1:General Rules
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SS EN 1997
Eurocode 7: Geotechnical Design - Part 2: Ground Investigation and
Testing
NA to SS EN 1997-1
Singapore National Annex to Eurocode 7: Geotechnical design - Part 1:
General rules
NA to SS EN 1997-2
Singapore National Annex to Eurocode 7: Geotechnical design - Part 2:
Ground investigation and testing
SS EN 1998-1
Eurocode 8: Design of structures for earthquake resistance - Part 1:
General rules, seismic actions and rules for buildings
SS EN 206
Concrete - Specification, performance, production and conformity
SS 544-1
Concrete - Complementary Singapore Standard to SS EN 206- Part 1
: Method of specifying and guidance for the specifier
SS 544 -2
Concrete - Complementary Singapore Standard to SS EN 206 - Part 2
: Specification for constituent materials and concrete
SS 560
Specification for steel for the reinforcement of concrete - Weldable
reinforcing steel - Bar, coil and decoiled product
Other Standards
BS EN 1536
Execution of special geotechnical works - Bored piles
BS EN 1998-5
Eurocode 8: Design of structures for earthquake resistance - Part 5:
Foundations, retaining structures and geotechnical aspects
BS EN 13670
Execution of concrete structures
BS 5228-1
Code of practice for noise and vibration control on construction and
open sites - Part 1:Noise
BS 5228-2
Code of practice for noise and vibration control on construction and
open sites - Part 2: Vibration
BS 5930
Code of practice for ground investigations
BS 8002
Code of practice for earth retaining structures
BS 8004
Code of practice for foundations
BS 8102
Code of practice for protection of below ground structures against water
from the ground
In the event that the standards or codes are revised or superseded, refer to the latest edition or the
appropriate substitution for the relevant subjects.
1.3.2
Technical References
Refer to the following technical reference for guidance in carrying out the works.
(a)
BRE Digest 251 Assessment of damage in low-rise buildings
(b)
BRE Special Digest 1 Concrete in aggressive ground
(c)
CIRIA Report 139 Water-resisting basement construction - A guide
(d)
CIRIA C517 Temporary propping of deep excavations - Guidance on design
(e)
CIRIA Report C580 (2003) Embedded Retaining Walls - Guidance for economic design.
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(f)
CIRIA C760, Guidance on embedded retaining wall design
(g)
EFFC/DFI, Best practice guide to tremie concrete for deep foundations (2nd Ed 2018)
(h)
EFFC/DFI, Guide to support fluids for deep foundations (1st Ed 2019)
(i)
FPS, Bentonite support fluids in civil engineering
(j)
ICE manual of geotechnical engineering, Volume 1: Geotechnical engineering principles, problematic soils
and site investigation
(k)
ICE manual of geotechnical engineering, Volume 2: Geotechnical design, construction and verification
(l)
ICE Specification for piling and embedded retaining walls
(m)
LTA Code of practice for Railway Protection (2004)
(n)
LTA Guide to carrying out restricted activities within Railway Protection and Safety Zones (2009).
(o)
LTA Guide to carrying out engineering works within road structure safety zone and engineering activity on
land adjoining public streets (2011)
(p)
PD 6687-1 Background paper to the National Annexes to BS EN 1992-1 and BS EN 1992-3
1.4
Trade Preamble
1.4.1
Development of Design Requirements
The notional design of the contiguous bored pile (CBP) or secant bored pile (SBP) wall works is indicated
in the drawings. The lateral support of strutting or ground anchor system indicated in terms of the
installation levels, the required stiffness and preloading are provided schematically where applicable.
Based on the information provided, undertake and provide for the SOs acceptance the following which
shall be carried out by appropriately qualified, competent and experienced personnel and PE:
(a)
Design or construction verification checks based on actual ground conditions to confirm the required size and
penetration length of CBP or SBP. Size and provide all temporary or permanent strutting elements and
walings for the CBP or SBP walls and take into all necessary considerations that the required control on
wall deflection can be achieved.
(b)
Prepare a response plan in the event that the temporary and or permanent CBP or SBP walls and strutting
elements do not perform as expected in the design in controlling the CBP or SBP wall deflection, and in the
event that measures taken to control ground movement and vibration do not perform satisfactorily.
Establish and indicate the alert levels and work suspension levels for forces and deflection of the CBP or
SBP on the drawings. The response plan shall be feasible for timely implementation with due
consideration of the construction sequence and site constraints.
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(c)
Prepare and submit all design and construction sequence, including drawings and reviews that shall be
endorsed by appropriately qualified, competent and experienced PE where applicable, to the SO for his
acceptance. The same submission shall be made to relevant authorities where applicable.
Submit the curriculum vitae (CV) of the personnel and specialists where applicable, to the SO for
acceptance.
1.4.2
Layout Drawings
Engage qualified and experienced personnel to prepare co-ordinated layout drawings indicating as a
minimum, pile dimensions, minimum penetration and material requirements for the CBP or SBP walls.
Submit the drawings to the SO for acceptance prior to commencing the installation works.
1.4.3
Co-ordination with Other Works
Co-ordinate with other contractor’s who may carry out other works at the same time at the site. Take into
account of site access, space occupation, safety and safeguarding of adjoining properties and each
other’s works.
1.4.4
Upholding of Adjoining Properties
Accept responsibility for the upholding of the adjoining buildings and roads, footpaths, etc., where
applicable, together with the mains and services from the time of taking possession of the Site through
the duration of the Works.
1.4.5
Verification of Site Information
1.4.5.1
Site Surveys
Verify and be satisfied that the information given in the existing site survey plans provided are accurate. If
necessary, engage a Registered Surveyor to carry out additional site survey before commencing any
work.
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1.4.5.2
Additional Site Investigation
Carry out additional ground investigation where additional information is needed for the Works or when
directed by the SO. Carry out the Works in compliance with Section C02-010 "Ground Investigation".
The permeability, strength of the subsoils and the groundwater level are key parameters to be
ascertained to determine the suitability of CBP or SBP wall and the required penetration depth of the
soft and hard piles to ensure overall stability and seepage cut-off.
Carry out the boreholes progressively prior to commencement of the Works in areas according to the
contractor’s construction programme. On completion of drilling, backfill the boreholes with a suitable
bentonite/cement mix.
Where rock is encountered, carry out sufficient number of boreholes before the pile excavation to
establish the quality and grade of the rock for design and execution requirements. Where cavity is
suspected from existing geological or published information in the area e.g. in limestone, carry out
adequate number of boreholes for sufficient information to carry out any pre-treatment works that are
necessary before pile installation commences.
Submit the location and schedule for the boreholes to the SOs acceptance prior to carrying out the
works. On completion, prepare the site investigation report and submit to the SO for acceptance.
Report immediately without delay to the SO any circumstance which indicates that in the Contractor’s
opinion, the ground conditions differ from those reported in or which could have been inferred from the
subsurface investigation reports.
1.4.5.3
Groundwater Level
Verify the data on groundwater level from available ground investigation reports. Carry out additional
water standpipes and piezometers if deemed necessary or as directed by the SO.
1.4.5.4
Contamination
Verify information on contamination identified or believed to be present on site.
In the event that contamination is either positively identified or suspected, draw to the attention of all
personnel working on site together with the need to take any precautionary measures in handling
contaminated materials, groundwater and obnoxious vapours from the ground.
1.4.6
Supervision of the Works
Engage qualified, competent and suitably experienced site personnel with the SOs acceptance, to
supervise the field works. Information on items to be checked or requiring monitoring during
construction shall be clearly identified and made known to the supervising personnel.
Site Supervision Plan for supervision the structural and geotechnical building works shall be prepared
and submitted by qualified, competent and experienced PEs to the relevant authorities, and in
accordance with the current guidelines issued under the Building Control Act and Regulations.
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1.4.7
Quality Control Plan
Submit and work to a quality control plan as agreed with the SO. Refer to Section G01010:Clause:1.4.7.
1.4.8
As-Built Pile Surveys
Surveying of as-built pile locations and pile eccentricities shall be carried out by a Registered Surveyor,
and submit the asâbuilt surveys to the SO in the format as directed, within 14 days after the piles have
been trimmed to the cut-off level.
S1.4.9
Building Damage Assessment
Carry out a Building Damage Assessment on the effects of ground movement to the neighbouring properties due to the
works, for the purpose of establishing suitable values for ‘Alert’ and “Work Suspension’ levels for monitoring. Submit to
SO with endorsement from a PE.
S1.4.10
Safety
Provide safety precautions to comply with all current legislation and regulations, notably:
a. Building Control Regulations
b. Code of Practice for Traffic Control at Work Zone
c. Factories (Building Operations and Works of Engineering Construction) Regulations
d. Factories Act
e. SS CP 79 Safety management system for construction worksites
f. For works within LTA Railway Protection Zone, ensure the works comply fully with Code of Practice for Railway
Protection.
Additionally, comply also with the following:
a. BRE Digest 251 (1995) Assessment of damage in low rise building
b. BS 8008: Guide to safety precautions and procedures for the construction and descent of machine- bored shaft
for piling and other purposes
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S1.5
Definitions and Abbreviations
a.
Accredited
The Testing Laboratory shall mean an organisation or laboratory
testing
accredited under the Singapore Laboratory Accreditation Scheme
laboratory
(SINGLAS) and fully equipped to carry out all tests and checks
required by the Specification.
b.
Cement
May also include all mineral admixtures such as pfa, ggbs, silica
fume etc that have cementitious properties as used in SS EN 197-1
c.
Obstructions
Include rock, concrete, reinforced concrete, solid brickwork, sheet
piles and the like, met within the excavations, but excluding those
met on the surface of the ground.
d.
Rock
Material with a large coherent mass of such size and strength, which
can be loosened or fractured only by blasting, or the employment of
heavy pneumatic tools, or by chemical expansion methods.
Loose boulders up to 1m³ in volume that can be removed are not
classified as rock.
2
PERFORMANCE REQUIREMENTS
2.1
Verification of Performance
When carrying out the performance verification as set out in C02-030-03:Clause:1.4.1 and in accordance
with SS EN 1997, take into account the following considerations:
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2.1.1
Wall Movements
The required size of CBP or SBP wall system is shown in the drawings, including the wall penetration
depth and the size of all permanent supports. Schematic lateral support in the form of temporary
strutting system or ground anchoring system indicated in terms of the installation levels, the required
stiffness and preloading are also shown on the drawings, where applicable.
Based on the actual ground condition encountered, verify the wall penetration depth and the adequacy
of CBP or SBP wall system as indicated in the drawings and in accordance with SS EN 1997. The
CBP or SBP wall movements shall be checked and reviewed throughout the execution to ensure that
the wall movements are within the allowable limits as specified or indicated in the drawings and in
accordance to the requirements of the relevant authorities. The CBP or SBP walls shall withstand all
loads on it; including those due to water pressure, earth pressure, surcharge loads, overburden, effects
of surrounding properties and varying load conditions due to different stages of construction. Check that
the application of partial factors assumed in the design and control on wall movement are verified by
taking into account the construction effects and field performance of the intended temporary supporting
system.
The verification shall be in accordance with SS EN 1997. Check that the ultimate limit states (ULS)
shall not be exceeded when appropriate load combinations and partial factors are applied in
accordance with SS EN 1997. In addition, control of wall deflection shall also satisfy serviceability limit
states (SLS) and the requirements of the Building Control Authority.
[Note 1: Refer also to guidance provided in CIRIA C517, C580, C760 and BS 8002.]
[Note 2: Temporary and permanent works shall be treated with equal importance and shall be well coordinated without ambiguity at all stages of design and construction. When an observational approach
is adopted, a highly co-ordinated site team would need to be employed, and a clearly-defined protocols
for decision-making and monitoring requirements shall be in place before construction commences.]
2.2
Embedment for Load Bearing
Where CBP or SBP walls are used for vertical load-bearing purposes, verify the required
embedment length by taking into account the actual ground conditions and the results of load tests of
preliminary elements in accordance or production piles in accordance with SS EN 1997.
2.3
Use of Support Fluid
Where support fluid is used, fulfil the following requirements:
(a)
Provide continuous support of the excavation.
(b)
Do not form a thick filter cake layer prior to concreting.
(c)
Have the ability to keep solid particles in suspension.
(d)
Be capable of being easily displaced and the interface layer remains on top of the rising concrete during
concreting.
(e)
Does not pollute the ground and groundwater at all stage.
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Does not coat the reinforcement such as to impair the bond between the reinforcement and concrete.
Bentonite, polymer or a mixture of bentonite and polymer support fluids may be considered for these
requirements.
Testing of support fluid shall be carried out to demonstrate compliance of limits as specified in BS EN
1536 or ICE specification for piling and embedded retaining walls if applicable, or FPS Bentonite
support fluids in civil engineering, or manufacturer’s instructions shall be complied with performance
criteria for CBP and SBP.
For CBP and SBP supporting vertical loads, refer to Section C04-010:Clause:2.2 for the
requirements on the performance criteria of piles under load testing. Load testing of single bored pile in
place of SBP is acceptable, provided the method of construction of both bored pile and SBP is similar.
[Note 1: Refer also to EFFC/DFI Guide to Support Fluids for Deep Foundations.]
2.4
Watertightness for CBP and SBP Walls
The walls formed shall be substantially watertight, that is, free from running water, percolating water or
seepage water. When total damp patches exposed on the excavated face of the wall exceeds 10% of
the visible area or any individual damp patch is found to be more than 4 m2, repair works shall be
carried out.
[Note 1: CBP is not considered to be watertight unless the gap between the piles is effectively sealed. In
general, hard/soft SBP walls are only regarded as providing watertightness in the short term only. A
good design practice is to provide a secondary lining system or provide a hard/ hard secant pile wall if
long-term water tightness is required.]
[Note 2: For guidance, refer to Table 2 of BS 8102: 2009 "Code of Practice for protection of below
ground structures against water from the ground"; and B1.9 of ICE "Specification for Piling and
Embedded Retaining Walls", 3rd Edition.]
2.5
Concrete
The concrete mix design shall satisfy the specification of concrete and shall take into account the
following:
(a)
the need for a high resistance against segregation
(b)
the need for adequate plasticity and good cohesiveness
(c)
the need to flow well
(d)
the need to be able to compact adequately by gravity
(e)
the need of sufficient workability retention for the duration of the placement procedure
(f)
the need of a concrete final set within 20 hours.
[Note 1: For tremie concrete, refer also to EFFC/DFI, Guide to Tremie Concrete for Deep Foundations.]
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MATERIALS
3.1
General
Refer to Section C04-010:Clause:3 and BS EN 1536 for general requirements of materials for CBP
and SBP walls, including concrete, reinforcement, support fluid and steel casing, etc.
3.2
Not In Use
S3.2
Temporary Casing
Temporary casing (not less than 6m) shall be provided during excavation of secondary piles for the
construction of SBP walls.
3.3
Self-hardening Slurry Mixes for SBP Walls
In the construction of SBP, self-hardening slurry mix may be used for primary piles instead of
concrete. The proposed mix shall be coherent and of a workability similar to concrete to facilitate
placing but shall remain sufficiently soft to facilitate cutting after the pile has been completed. The
compressive strength and permeability of the self-hardening slurry mixes shall meet the minimum
design requirements specified by the PE who is responsible for the design of the slurry mix.
3.4
Support Fluid
3.4.1
Bentonite
Bentonite supplied to the Site shall comply with BS EN 1538.
If bentonite is used, in any 100 tonnes of bentonite supply, moisture content shall not deviate more
than ±2%. Maximum moisture content shall not exceed 15%. Residue of diameter greater than 75
µm shall not exceed 4%. Bentonite slurry properties obtained at the recommended dosage by the
manufacturer/ supplier shall conform to Tables 1 and 2 of BS EN 1538.
3.4.2
Reuse of Bentonite
Upon reuse, the density, maximum sand content, viscosity and pH of bentonite shall to comply with the
criteria as set out in Tables 1 and 2 of BS EN 1538.
3.5
Concrete
Concrete and constituent materials for CBP and SBP wall shall be in compliance with SS EN 206 and
SS 544-1 and SS 544-2.
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3.6
Additions and Admixtures
Additions and admixtures when used in the concrete mix shall comply with SS EN 206 and SS 544.
3.7
Reinforcement
For general requirements of reinforcement, refer to Section C03-020:Clause:3. The steel
elements used in CBP and SBP walls shall comply with SS EN 10080.
4
WORKMANSHIP
4.1
General
Refer to Section C04-010:Clause 4 and BS EN 1536 for all general requirements of execution and
workmanship for CBP and SBP walls, including boring, support fluid, concreting and casing support, etc.
For tremie concrete, refer to EFFC/DFI, Guide to Tremie Concrete for Deep Foundations, and for
supporting fluid, refer also to EFFC/DFI Guide to Support Fluids for Deep Foundations.
4.2
Placing Self-Hardening Slurry Mixes for Soft Pile of SBP Wall
Place using methods appropriate to the mix employed. Use a tremie in accordance with C04010:Clause:4.7, or proprietary methods as proposed and accepted by the SO.
4.3
Setting Out and Tolerances
4.3.1
Setting Out
Establish all lines, levels and be responsible for the correct positions of all piles. Carry out setting out
from the main grid lines of the proposed structure. Immediately before installation of the pile, mark the
pile position with suitable identifiable pins or markers.
4.3.2
Tolerance for SBP
4.3.2.1
Deviation of Centre Line
Maximum permitted deviation of pile centre at cut-off from specified position shall be 25 mm in any
direction.
Allow an additional tolerance of 5 mm for every additional metre of the cut-off level below the top of the
guide wall for hard/hard secant piles.
Allow an additional tolerance of 10 mm for every additional metre of the cut-off level below the top of
the guide wall for hard/soft secant piles.
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4.3.2.2
Verticality
For hard/hard secant piles, verticality tolerance is 1:200 for the exposed face of the pile unless otherwise
agreed.
For hard/soft secant piles, verticality tolerance is 1:100 for the exposed face of the pile unless otherwise
agreed.
4.3.2.3
Allowance for Overbreak
An additional 100 mm is allowed for concrete protrusions resulting from overbreak in the ground
unless otherwise agreed.
Where very soft layers or removal of obstructions are anticipated, notify the SO to agree on an additional
tolerable allowance for the overbreak.
4.3.2.4
Reinforcement
Vertical tolerance on level of steel projecting from cut-off shall be +150 mm/-50 mm (i.e. a maximum of
150 mm higher or 50mm lower), unless otherwise agreed.
4.3.2.5
Recesses
For recesses formed by box-outs within the pile shaft, vertical tolerance is as C02-030- 03:Clause:4.3.2.4
and rotational tolerance shall be 10 degrees.
4.3.3
Tolerance for CBP
4.3.3.1
Deviation of Centre Line
Maximum permitted deviation of pile centre at cut-off from specified position shall be 75 mm in any
direction.
Allow an additional tolerance of 10 mm for every additional metre of the cut-off level below the top of
the guide wall.
4.3.3.2
Verticality
Verticality tolerance is 1:100 for the exposed face of the pile, unless otherwise agreed.
4.3.3.3
Allowance for Overbreak
An additional 100 mm is allowed for concrete protrusions resulting from overbreak in the ground
unless otherwise agreed.
Where very soft layers or removal of obstructions are anticipated, notify the SO to agree on an additional
tolerable allowance for overbreak.
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4.3.3.4
Reinforcement
Vertical tolerance on level of steel projecting from cut-off shall be +150 mm/-50 mm (i.e. a maximum of
150 mm higher or 50 mm lower), unless otherwise agreed.
4.3.3.5
Recesses
For recesses formed by box-outs within the pile shaft, vertical tolerance is as C02-030- 03:Clause:4.3.2.4
and rotational tolerance shall be 10 degrees.
4.3.4
Design Consideration Due to Construction Tolerance
CBP and SBP design and execution shall take into account the construction tolerances agreed by the
SO.
4.3.5
Guide Walls
Guide walls shall be used in the construction of SBP to ensure sufficient interlock. In the case of CBP,
guide wall is only required if a more stringent construction tolerance has been specified. Guide walls
should be constructed in reinforced concrete or other suitable materials.
5
VERIFICATION AND SUBMISSIONS
5.1
General
Refer to Section C04-010:Clause:5 for all general requirements of verification and submissions for CBP
and SP walls, including method statements, quality control plans, records, as-built details,
compliance tests and pile tests, etc.
5.2
Soft Pile of SBP Walls
5.2.1
Trial Mixes for Self-hardening Slurry Mixes
Prepare trial mixes and carry out tests for suitability, unless there is adequate existing data
demonstrating the mix proportions and method of manufacture that will produce hardened material of the
required strength and other properties such as permeability, shrinkage, durability and consistency for
compaction.
5.2.2
Testing of Self-Hardening Mixes
Check for compliance with the mix proportions.
[ Note 1: The ICE specification for the construction of slurry trench cut-off walls provides guidance on the
requirements of self-hardening mixes.]
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1
GENERAL
Read this Section with G01-010 "General Requirements" and all other contract documents.
1.1
Scope
This Section covers the requirements for soil improvement works using jet grouting method.
1.2
Related Sections
Read this Section in conjunction with the relevant requirements of the following sections:
1.3
C01-020
Condition Survey
C02-010
Ground Investigation
C02-020
General Earthworks (Excavation and Filling)
C02-050
Instrumentation and Monitoring
Standards, Codes, Regulations and Technical References
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1.3.1
Standards and Codes
Unless otherwise agreed by the SO, ensure all of the Works comply with the relevant requirements of
the standards and codes listed below or referenced in the body of the Specification. Alternative
standards and codes may be proposed for approval by the SO, provided it can be demonstrated that the
alternative standards and codes comply with the requirements of the standards specified. All standards
and codes quoted are the current version, unless specific year references are noted.
In the event that the standards or codes are partially superseded or have become obsolete, refer to
the current edition or the approved substitution for the relevant clauses.
Singapore Standards
SS EN 197-1
Cement - Composition, specification and conformity criteria for common
cements
SS EN 206
Concrete - Specification, performance, production and conformity
SS EN 1997-1
Eurocode 7: Geotechnical design - Part 1: General rules
SS EN 1997-2
Eurocode 7: Geotechnical design - Part 2: Ground investigation and
testing
Other Standards
1.3.2
BS EN 1008
Mixing water for concrete
BS EN 12390-3
Testing hardened concrete - Part 3: Compressive strength of test
specimens
BS EN 12716
Execution of special geotechnical work - Jet grouting
BS 1377
Methods of test for soils for civil engineering purposes
BS 5228
Code of practice for noise and vibration control on construction and open
sites
BS 5930
Code of practice for ground investigations
BS 8004
Code of practice for foundations
.
.
Technical References
Refer to the following technical references for guidance in carrying out the Works:
(a)
BRE Digest 251 Assessment of damage in low-rise buildings
(b)
CIRIA C514 Grouting for ground engineering
(c)
CIRIA C573 A guide to ground treatment
(d)
CIRIA C760 Guidance on embedded retaining wall design
(e)
FHWA GEC 013 (2017) Ground modification methods reference manual - Volume II
(f)
ICE manual of geotechnical engineering, Volume 1: Geotechnical engineering principles, problematic soils
and site investigation
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ICE manual of geotechnical engineering, Volume 2: Geotechnical design, construction and verification
1.4
Trade Preamble
1.4.1
Contractor’s Submissions and Proposals
Based on available information on ground conditions, existing structures and utilities, operational
constraints and the required performance of the improved ground as set out in Section C02-04001:Clause:2.1, engage a qualified specialist to take full responsibility for the following:
(a)
Plan for the design mix, injection pressures, injection quantities and other related operational parameters
before the execution.
(b)
Plan for the complete grouting operation, including selecting the appropriate construction methods and
techniques, equipment, grout mix, parameters and method of spoil containment and disposal.
(c)
Provide review and adjustment during the execution when necessary.
(d)
Propose as a response plan in the event that measures taken to control ground movement or/ and vibration
do not perform satisfactorily or exceed the specified limits
Submit all proposals for the SOs acceptance before work commences.
1.4.1.1
Review of Proposals
Engage a qualified and competent PE with proven experience in relevant ground treatment techniques, for
the SOs acceptance, for the following:
(a)
Review the proposals as in Section C02-040-01:1.4.1.
(b)
Review the quality of the jet grouting works, suitability of the selected jet grouting techniques and operating
parameters during the jet grout trial as well as the actual production works.
(c)
Carry out a Building Damage Assessment on the effects of ground movement to the neighbouring
properties due to the Works, for the purpose of establishing suitable values for review levels for
instrumentation monitoring.
The PE shall endorse all required submissions, including method statement, test reports and proposals on
remedial measures, etc. to the SO for acceptance.
Submit the curriculum vitae (CV) of the PE to the SO for acceptance.
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1.4.1.2
Layout Drawings for Jet Grouting
Engage qualified and experienced personnel to prepare co-ordinated layout drawings for the proposed
jet grout columns indicating as a minimum, proposed column diameter, spacing, top and bottom level.
Submit the drawings endorsed by qualified PE to the SO for acceptance prior to commencing the
installation works.
1.4.2
Co-ordination with Other Works
Co-ordinate with other contractor’s who may carry out other works at the same time at the Site. Take
account of site access, space occupation, safety and safeguarding of adjoining properties and each
other’s works.
1.4.3
Condition Survey
Where applicable, prior to and upon completion of the site works, carry out a condition survey on
adjacent buildings and utilities within the zone of influence in accordance with the requirements of
Section C01-020 "Ground Investigation". Submit all records to the SO and adjacent property owners
where directed.
1.4.4
Instrumentation and Monitoring
Provide instrumentation to monitor ground movement, vibration and condition of adjacent properties. Refer
to Section C02-050:Clause:3.1, and drawings for the schedule of instrumentation required. If necessary
or as required by the authorities, propose and provide additional instrumentation and monitoring for
records.
Take cognisance of and co-ordinate with other contractor’s on site who may be carrying out instrumentation
and monitoring works to avoid duplication of installation and readings.
For general requirements of instrumentation and monitoring works, refer to Section C02-050.
1.4.5
Upholding of Adjoining Properties
Accept responsibility for the upholding of the adjoining buildings and roads, footpaths etc., where
applicable, together with the mains and services from the time of taking possession of the site through
the duration of the Works.
1.4.6
Verification of Site Information
1.4.7
Site Surveys
Verify and be satisfied that the information given in the existing site survey plans provided are accurate. If
necessary, engage a Registered Surveyor to carry out additional site survey before commencing any
work.
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1.4.7.1
Additional site investigation
Carry out additional ground investigation where additional information is needed for the Works or when
directed by the SO. Carry out the Works in compliance with Section C02-010.
Carry out the boreholes progressively prior to commencement of the Works in areas according to the
contractor’s construction programme. On completion of drilling, backfill the boreholes with a suitable
bentonite/cement mix.
Submit the location and schedule for the boreholes for the SOs acceptance prior to carrying out the
Works. On completion, prepare the site investigation report and submit to the SO for acceptance.
1.4.7.2
Contamination
Verify information on contamination identified or believed to be present on site.
In the event that contamination is either positively identified or suspected, draw to the attention of all
personnel working on site together with the need to take any precautionary measures in handling
contaminated materials, groundwater and obnoxious vapours from the ground.
1.4.8
Existing Services Affected by the Works
Refer to preliminaries and conditions of contract for the requirements to deal with existing services
affected by the Works.
1.4.9
Site Protection
Protect all equipment and working area using fencing or other methods as accepted.
1.4.10
Obstructions
If any obstructions such as existing fences, structures, footings, boulders, concrete blocks, pipes, drains,
driveways or ramp etc. are encountered during drilling, submit proposals for their removal or
repositioning of the jet grout column to avoid the obstructions for the SOs acceptance.
1.4.11
Supervision of the Works
Engage competent and suitably experienced site personnel to the SOs acceptance, to supervise the
field works. Information on items to be checked or requiring monitoring during construction shall be clearly
identified and made known to the supervising personnel.
1.4.12
Quality Control Plan
Submit and work to a quality control plan as agreed with the SO. Refer to G01-010:Clause:1.4.7.
1.5
Definitions and Abbreviations
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1.5.1
Definitions
1.5.1.1
Accredited Testing Laboratory
A laboratory accredited under SAC-SINGLAS to carry out specific test(s)required by the Specification.
1.5.1.2
Cement
Include all mineral admixtures such as pulverized fuel ash (PFA), ground granulated blast- furnace
slag (GGBS), silica fume, etc. that have cementitious properties as proposed in SS EN 197-1.
1.5.1.3
Grout
Pumpable material (suspension, solution, emulsion) composed of water, binder and additives, that is
used as high energy fluid or for cementing and which develops strength, e.g. measured as unconfined
compressive strength, over time.
1.5.1.4
Hydraulic binder
Cement or similar product used in aqueous suspension to produce grout.
1.5.1.5
Jet grouted element
Volume of soil or weak rock treated through a single borehole.
1.5.1.6
Jet grouting
A process of hydraulic disaggregation of the soil or weak rock, which is achieved by a high- energy jet of
a fluid which can be the cement agent itself, and its concurrent mixing with, and partial replacement by
grout, to create a jet grouted element after hardening of the hydraulic binder.
1.5.1.7
Jet grouting parameters
Parameters defined as number and diameter of nozzles, pressure of the fluid(s), flow rate of the fluid(s),
pressure and flow of the air (if used), grout or fluid composition, rotation speed of the jet grouting string,
and rate of withdrawal or insertion of jet grouting string.
1.5.1.8
Radius of influence
Distance of hydraulic disaggregation of soil by the jet, measured from the axis of the monitor that is
mounted close to the end of the jet grouting string holding the nozzle.
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1.5.1.9
Spoil return
Surplus mixture of hydraulically disaggregated soil or weak rock and introduced fluids arising from the jet
grouting process, and normally flowing to the ground surface via the annulus of the jetting borehole.
1.5.2
Abbreviations
1.5.2.1
SPT
Standard Penetration Test
1.5.2.2
UCS
Unconfined Compressive Strength
2
PERFORMANCE REQUIREMENTS
2.1
Contractor’s Proposal
2.1.1
General
The required extent of ground treatment by jet grouting method is specified or indicated in the drawings,
together with an indication of the required thickness, treatment area percentage and the depth of the
grout layer to be installed.
Plan the operation and methods taking into account the required improved ground properties as provided
in Section C02-040-01:Clause:2.1.2, based on the actual ground conditions revealed by the existing
boring logs and/or the additional geotechnical investigation as well as instrumentations and tests carried
out during the works. Take into consideration all artificial or natural physical obstructions, site and ground
conditions.
2.1.2
Improved Ground Properties
After completion of the ground improvement works, carry out coring and tests, with appropriate sample
quality class, to the acceptance of the SO to verify that the full thickness of jet grouted element achieves
design strength (UCS) and stiffness or deformation characteristics as specified and indicated in the
drawings.
The cored samples shall satisfy the following:
(a)
The grouted section of jet grouted element shall not be less than 85% of the total intended grout
length/layer thickness specified or as required by the SO. The continuity requirement shall be determined by
the ratio of core recovery length to the total core length. In this computation, core recovery length is taken as
the total length of recovered core minus the sum of lengths of untreated soils that extend across the entire
diameter of the core.
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(b)
The strength and stiffness shall surpass the confidence level required by the SO.
(c)
UCS is the design UCS at 28 days unless otherwise specified or directed by the SO.
When indirect methods such as SPT, etc. are used to determine the in-situ strength and stiffness of the
jet grouted element, proper site-specific correlation would need to be established and agreed with the
SO.
[Note 1: To specify UCS and Deformation Modulus in the drawings. Deformation modulus can be
specified in terms of tangent modulus, or tangent modulus/secant modulus at 50% peak strength, etc.
as appropriate. In some practice, target values for jet grouted elements in terms of UCS of 600 kPa and
stiffness of 150 MPa have been used. Where applicable, maximum permeability required may also
be specified.
Note 2: Young’s modulus refers to the secant modulus of the stress strain curve at 50% of failure
strength (UCS) as defined above or as specified by the SO.
Note 3: Longer duration such as 56 days may be considered in applications where for example, ground
granulated blast furnace slag (GGBS) is used in the grout mix design.
Note 4: Acceptance criteria for coring stated above should be treated with caution. Good core recovery
may be difficult when gravels and/or coarse material are present in the jet grouted element or when the
required jet grouted element strength is lower than extremely weak rock.
Note 5: Design UCS and stiffness specified should be practically reasonable and take into account
the anticipated ground and groundwater conditions.
Note 6: Jet grouted element formed in non-homogeneous ground condition would exhibit inherent
variability of test results, this should be considered accordingly in the overall design and acceptance
criteria.]
Note 7: Guidance in determining characteristic strength of the jet grouted element from test results is
provided in BS EN 12716.]
2.1.3
Control of Ground Movement and Vibration
Take care in the design and execution of the works to control settlement, heave or horizontal movement,
and vibration recorded at any monitoring point to avoid damage to buildings or utilities in the vicinity of
the Works.
Propose suitable ground movement control criteria for SOs acceptance, taking into account the
vulnerability and sensitivity of the adjacent properties and appropriate limits that meet the statutory
requirements after carrying out the damage assessment as specified in Section C02- 04001:Clause:1.4.1.1.
State the values for check, alert and work suspension levels in the submission in accordance with the
statutory requirements.
Notwithstanding the above, ensure that ground movements and vibrations arising from the Works
do not exceed the limits provided as follows:
(a)
Generally, comply with the requirements of BS 5228-1.
(b)
Unless otherwise directed by the SO, refer to Section C02-050:Clause:4.2.2 for general restrictions on
ground movements and vibration limits for adjacent structures where relevant.
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MATERIALS AND EQUIPMENT
3.1
General
Refer to BS EN 12716 for general requirements of materials and equipment for jet grouting.
3.2
Flushing Medium
Use non-toxic materials as flushing medium for drilling or as part of the grout mix subject to the acceptance
of the SO.
3.3
Water
Water used for grout shall be clean and contain no chemicals deleterious to the setting and strength
development of the grout. Mixing water shall comply with BS EN 1008 and SS EN 206.
3.4
Other Materials
Use any other materials or chemicals for the works only with the approval of the SO.
Ensure that all materials are non-toxic and non-corrosive and are protected from contamination or
pollution at all times.
3.5
Drilling Rig and Grouting Plant
Equip the drilling rig with pressure gauges/devices, flow meters and other measuring devices,
including a monitor mounted close to the end of the jet grouting string holding the nozzle to allow
regular checks on critical operating parameters such as fluid pressure, grout injected rate, monitor
rotation and withdrawal rate. Automated instrumentation that allows continuous recording of these data
should be used for monitoring. Maintain all plant and equipment used in good operating condition at all
times.
4
WORKMANSHIP
4.1
Jet Grout
4.1.1
General
Refer to BS EN 12716 on the requirements of workmanship for jet grouting.
4.1.2
Storage and Handling of Grout Materials
Deliver grout materials in undamaged unopened containers bearing the manufacturer’s original labels.
Store and handle in accordance with the recommendations of the manufacturer.
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4.1.3
Collection and Disposal of Effluent
Collect all drilling and grouting effluent in trenches, pits or tanks and do not allow spreading over or
outside the Site.
Take measures to ensure all effluent is not allowed to enter the public drainage system.
Remove all effluent from the Site and dispose of it in accordance with the regulations of the appropriate
authority.
4.2
Control of Ground Movements
4.2.1
Construction Sequence
Ensure that the jet grouting operation follows the agreed method and sequence, and to the approval of
the SO.
4.2.2
Grouting in Soft Clay
Jet grouting in thick soft clay deposits may lead to significant ground heave/movement. The following
are possible measures to control ground movements when jet grouting in thick soft clay is carried out and
may be specified according to individual project circumstances:
4.2.3
(a)
Minimise the angle of inclination of the drill holes, as far as it is practical.
(b)
Maintain the drill hole size such that slurry/spoils outflow can be maintained. Re-drill the hole whenever
necessary. Depending on observations on site, be ready to change the drill diameter whenever
necessary.
(c)
When loose sand and other collapsible soils are present and the drill hole is to be significantly inclined, use of
casings to prevent drill hole collapse is advised.
(d)
Ensure that an adequate size of annulus is provided for a free flow of spoil return at all times.
Filling of Empty Bore
Fill the empty bore above the jet grout column with grout during the extraction of grouting monitor
that is mounted close to the end of the jet grouting string holding the nozzle.
4.3
Obstructions
If obstructions consisting of artificial or man-made materials or structures in the ground, are encountered,
review and agree with the SO, on steps to be taken to ensure that the affected ground is treated
satisfactorily.
4.4
Tolerances
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4.4.1
Setting Out
Establish permanent datum level points, base lines and grid lines.
Maintain these setting out guides as necessary to the satisfaction of the SO.
Set out the position of each treatment point with a suitable identifiable pin or marker. Check that
each treatment point has a unique reference number for record purposes.
4.4.2
Position
The maximum permitted deviation of the grout-hole centre from the centre shown in the setting- out is 75
mm in any direction at commencing surface level.
4.4.3
Verticality
The maximum permitted deviation of the finished grout hole from the vertical axis for vertical jet grouting at
any level is 1 in 75.
4.5
Protection to Treated Areas
Ensure that during the course of the Works, displacement or damage does not occur to completed
areas of ground treatment which can impair their performance.
Submit to the SO the planned sequence and timing for the Works, having regard to the avoidance
of damage to completed areas of ground treatment.
4.6
Completion of the Works
After completing the grouting procedures, remove all grouting accessories or similar elements, and
backfill the drill holes in the ground with cement grout. Restore the Works to its original condition as
approved by the SO.
5
VERIFICATION AND SUBMISSIONS
5.1
Submission
5.1.1
Method Statement for Jet Grouting
Submit a detailed method statement to the SO for acceptance before jet grouting work commences.
Include the following:
(a)
Proposals for a jet grouting trial, including the location and monitoring of the trial
(b)
Full details of proposed plant and method of drilling, including proposed flushing medium
(c)
Specification and details of the equipment to be used such as grout mixers, injection pumps, injection
nozzles and drilling rigs and jet grout equipment arrangement
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(d)
Details of the method to monitor the location, depth and verticality of the jet grout nozzles
(e)
The selected operational parameters for the jet grouting, including injection pressure and rate of injection of
the air, water and grout (as appropriate) withdrawal rate and rotation rate, and injection nozzle size, type
and number
(f)
Method of measuring and controlling the operational parameters
(g)
Depth and thickness of jet grout layer, including a layout plan showing installation location of each jet grout
column, the column size, depth, overlap and spacing
(h)
Proposed methods for the setting out of each grout column
(i)
Sequence of work for installing each grout column and the overall sequence of construction for the jet grout
layer, taking into consideration of the anticipated time required for installation of the ground treatment from
commencement of site works to completion
(j)
Plan the layout of jet grout columns to avoid possibility of shadows as a result of obstruction in the line of
jetting such as in the case of irregular retaining walls, e.g. steel pipe piles and sheet piles
(k)
Details of method to avoid critical utilities
(l)
Method to complete a grout column in case grouting process is discontinued before the column is completed
due to equipment breakdown or other reasons
(m)
The target strength and stiffness of the grout columns and the proposed grout mix
(n)
Methods used to monitor and control ground movement during drilling and grouting
(o)
The method of monitoring and checking the stability of neighbouring properties, roads, utilities and other
underground structures
(p)
Methods of testing for the quality of the grout mix and the jet grouted elements.
(q)
Technical details and test reports on chemical admixtures (if any)
(r)
Details of storage and handling of grout materials
(s)
The methods used for collecting, transporting and disposal of the slurry
(t)
Risk identification, risk management and environmental hazards analysis
(u)
Samples of field data collection forms/printouts and daily field reports
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5.1.2
Programme
Submit a provisional and detailed programme for the execution of the Works prior to commencement.
Provide a daily update of the intended programme of ground treatment for the following day and shall give
24 hours notice of the intention to work outside normal hours and over weekends, where this is
permitted.
5.1.3
Quality Control Manual
Submit a quality control manual containing a Quality Assurance / Quality Control (QA/QC) programme for
the Works to the SO for acceptance within a directed time frame.
The quality control manual is to include at least information on the following:
5.2
(a)
Quality policy
(b)
Organisational charts and responsibilities
(c)
Internal quality control and audits
(d)
Facilities and equipment
(e)
Calibration and testing of equipment
(f)
Testing and inspection procedures
(g)
Subcontractor’s and suppliers
Calibration of Equipment
Calibrate all measuring devices before commencement of the Works, and submit the records of the
calibration done not earlier than 6 months to the SO.
5.3
Jet Grouting Trial or Preliminary Field Tests
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5.3.1
General
Before executing the proposed main jet grouting works, carry out a jet grouting trial or preliminary field
tests to demonstrate the suitability of the proposed methods. Perform the jet grouting trial in full
accordance with the accepted method statement.
Review the method statement after taking account of the results of the trial and re-submit a revised
method statement if necessary. The revised method statement shall be subject to the SOs acceptance
prior to the commencement of the main jet grouting works.
Location of the trial should be such that its sub-surface conditions, inclusive of material type and depth, are
representative of the conditions to be treated in the main jet grouting works.
In the case that multiple layers of jet grouting are required in the main jet grouting works, conduct
the trial on multiple layers.
Conduct the trial using the materials and equipment to be used in the main jet grouting works.
5.3.2
Details of Trial
Ensure that the trial jet grouting consists of a series of overlapping columns formed at similar depth and
ground conditions as shown in the drawings.
5.3.3
Use of Trial Grout Columns
Unless otherwise accepted by the SO, do not use trial jet grout columns as working jet grout columns.
5.3.4
Monitoring
Monitor ground movement during jet grouting works. Specifics of the monitoring shall be submitted to and
agreed with the SO.
5.3.5
Results
Submit the results of the trial jet grouting to the SO, together with an interpretative report assessing the
results of the trial and proposing any necessary changes to the method statement.
5.3.6
Rejection
In the event that the jet grouting trial fails to satisfy the required acceptance criteria, reject the method that
is used for the trial.
Propose remedial measures to rectify the defects and carry out another trial for the acceptance of the
SO to demonstrate the suitability of the measures
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5.3.7
Quality Control of Jet Grout Trial
Propose in details and carry out tests to the acceptance of the SO to verify that the full thickness of
the trial jet grout layer achieves in-situ strength and stiffness as specified in the design or indicated in
the drawings or as directed by the SO.
Conduct tests for the trial jet grouting works to demonstrate the effectiveness of the trial jet grouting by
obtaining cores through the full depth of the jet grouted element at boreholes as shown on the drawings.
Coring should be conducted at overlapping locations to ensure the required diameter is achieved. Fully
log the cores in accordance with BS 5930 and test the samples for strength and stiffness in accordance
with BS EN 12390-3. Refer to BS EN 12716 on the sample quality class for tests as appropriate. When
indirect test method such as SPT is used for assessing the strength and stiffness of the jet grouted
element, carry out a minimum of 3 additional SPT tests at the borehole(s) located at the overlapping
areas where cores are retrieved.
Use the strength and stiffness test results obtained from the cores correlate with SPT N values taken at
comparable depths and this correlation shall be agreed with the SO and used as the basis for indirect
tests conducted for subsequent quality control.
[Note 1: Use past references of comparable experience instead of a single project to determine correlation.
In most instances, the data from one project is not adequate.]
Where the grouted layer is to reduce permeability, perform permeability tests on core samples for the
acceptance of the SO.
[Note 2: There is no readily available permeability equation for testing the permeability of a finite volume
material in a soil of different permeability. If general permeability equation is used, the test results should
account for such application and adjustments may be required to the results.]
[Note 3: Refer to BS EN 12716 on permeability tests.]
Carry out the field testing and laboratory testing on or before 28 days or other duration from the formation
of trial jet grouting as agreed with the SO.
5.3.8
Report
Compile, evaluate and assess the results of the testing and the resulting correlations in reports which shall
be endorsed by both the qualified specialist for the jet grouting works and the qualified, competent and
experienced PE, and submit with recommendations for the SOs acceptance prior to commencement of
the production jet grouting works.
5.4
Quality Control of Main Jet Grouting Works
5.4.1
Grout Mix
Check the grout mix by measuring the specific gravity using a mud balance. Conduct at random, but not
less than twice a day per rig, for every rig that is grouting that day.
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5.4.2
Spoil return
Ensure there is continuous flow of spoil return through visual observation. Check the specific gravity of the
spoil return using mud balance if unexpected behaviour of the spoil return is observed.
5.4.3
Works Testing
Carry out all necessary testing of the contract works to demonstrate full compliance with the specified
performance requirements. Perform these tests within 28 days of jet grouting.
Carry out the following tests as directed by SO.
5.4.3.1
SPT Tests
SPT tests may be used as a supplementary test for direct coring test provided a site-specific correlation
has been established during trial jet grouting.
When SPT test is used, it should be conducted at the overlapping areas of the jet grouted element.
Unless otherwise directed by the SO, each cored hole required may be replaced by 2 boreholes with
SPT carried out at the top, middle and bottom level of the jet grouted element at each borehole.
However, the replacement of coring with SPT shall be limited to no more than 50% of the total number of
coring tests specified.
5.4.3.2
Core Samples
Carry out coring tests for core samples at locations as indicated in the drawings or agreed with the SO.
Unless otherwise agreed by the SO, the number of tests shall not be less than the minimum test
frequency as provided in BS EN 12716.
To minimise sample disturbance, triple core barrel and large diameter sampler shall be used for coring.
Coring shall be carried out through the full depth of the jet grouted element at the overlapping areas.
A minimum of 3 samples shall be taken from the top, middle and bottom of each cored hole for testing of
strength and stiffness requirements.
5.4.3.3
Laboratory Tests
Carry out the laboratory tests on the test samples taken from the cores obtained at an accredited
testing laboratory. The quality requirements of the jet grouted element is considered satisfactory if the
desired acceptance criteria are achieved for each set of at least 3 core samples being tested at each
location. Refer to BS EN 12716 on sample quality.
(a)
Perform unconfined compression tests with stress-strain measurement on the core samples to evaluate the
UCS and Young’s modulus or Deformation Modulus as specified.
(b)
Perform permeability tests on core samples to the acceptance of the SO, where the grouted layer is to
reduce permeability.
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5.4.4
Acceptance
Jet grouted element will not be accepted if any zone of treated soil does not meet or satisfy the
performance requirements. Where the specified jet grout performance requirements are not met,
repeat and retest the grouting to the SOs satisfaction.
5.4.5
Remedial Measures
In the event that the tests fail to satisfy the required jet grouted elements quality and condition on
continuity, reject the portion of the works represented by the tests unless otherwise agreed. Propose
remedial measures to rectify the unsatisfactory works in the affected area to the acceptance of the
SO.
5.4.6
Report on Test Results
Submit a full report on the test results, including assessment of the results and any proposals for remedial
work to the SO. The report shall include the following information:
(a)
The depth of the start and finish of each core run
(b)
The core recovery length for each core run and percentage of total core recovery with reference to definition
in Section C02-040-01:Clause:
(c)
The date when each section of the core was drilled
(d)
Photograph of the core in core box taken under natural light with standard scale and colour chart
(e)
Results of field and laboratory testing undertaken to ascertain the quality of the jet grouted element
5.5
Records and Reports
5.5.1
Records
Keep careful records for each point of installation. Submit all grouting records to the SO. The records shall
include for each jet grout column:
(a)
Location and reference number
(b)
Date and time of installation
(c)
Reduced levels for the ground level, the top and base of the jet grout column
(d)
Inclination of the jet grout column
(e)
Details of casing size and length if used to prevent collapse of drill hole
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5.5.2
(f)
Drilling rig identification
(g)
Length of drilling and type of flushing medium
(h)
Duration and timing of each major activity
(i)
All operating parameters as used for the jet grout column installation, including water pressure, air pressure,
grout pressure (as appropriate) and rate of rotation and withdrawal flow rate, nozzle size, nozzle type and
number of nozzles
(j)
Volume of grout, including grout ingredients and mix proportions used
(k)
Grout density
(l)
Observations on spoil return, breakdowns, interruptions during drilling, grouting and any other relevant events
(m)
Display monitoring data in an acceptable continuous graphical format that facilitates rapid visual evaluation
of the results of the Work
(n)
Pre-cutting details, if used.
Summary Report
At the completion of any continuous block or section of Jet Grouting, prepare a summary report. This
report shall provide:
(a)
As built drawings showing the layout, inclination and installed depth of each jet grout column
(b)
The results of all including additional geotechnical investigation carried out related to the jet grouting works
(c)
The location and final values of all monitoring carried out during and after the jet grouting works, with graphs
showing the development trend of movement, load or pressure with time throughout the jet grouting works
(d)
The results of the quality control testing carried out at site and proposed remedial works, where applicable.
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(10) C02-050 Instrumentation and Monitoring
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1
GENERAL
Read this Section with G01-010 "General Requirements" and all other contract documents.
1.1
Scope
This Section covers the requirements for instrumentation using a number of different methods and
monitoring of the various construction works for the following:
(a)
Determine ground movements as a result of construction.
(b)
Determine the effects of settlement on existing structures, services and utilities.
(c)
Provide settlement and movement data in a form that will allow direct comparison with performance criteria
and design expectations.
In addition, instrumentation is installed to provide construction control, design verification, safety, legal
protection and ground investigation data.
1.2
Related Sections
Read this Section in conjunction with the relevant requirements of the following section:
C02-010
1.3
Investigation
Standards, Codes, Regulations and Technical References
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1.3.1
Standards and Codes
Unless otherwise agreed by the SO, ensure all of the Works comply with the relevant requirements
of the standards and codes listed below or referenced in the body of the Specification. Alternative
standards and codes may be proposed for approval by the SO, provided it can be demonstrated that
the alternative standards and codes comply with the requirements of the standards specified. All
standards and codes quoted are the current version, unless specific year references are noted.
In the event that the standards or codes are partially superseded or have become obsolete, refer to
the current edition or the approved substitution for the relevant clauses.
Singapore Standards
SS EN 1997-1
Eurocode 7 - Geotechnical design - Part 1: General rules
SS EN 1997-2
Eurocode 7: Geotechnical design - Part 2: Ground investigation and
testing
Other Standards
1.3.2
BS EN ISO 18674-1
Geotechnical investigation and testing - Geotechnical monitoring by field
instrumentation - Part 1: General rules
BS EN ISO 18674-2
Geotechnical investigation and testing - Geotechnical monitoring by field
instrumentation - Part 2: Measurements along a line - extensometers
BS EN ISO 18674-3
Geotechnical investigation and testing - Geotechnical monitoring by field
instrumentation - Part 3: Measurements across a line - inclinometers
BS8574
Code of practice for the management of geotechnical data for ground
engineering projects
Technical References
Refer to the following technical references for guidance in carrying out the Works:
(a)
Land Surveyors Board Singapore (LSB) Directives on Engineering & Hydrographic Survey Practices,
Version 4.0, 2013
1.4
Trade Preamble
1.4.1
Submissions and Proposals
Based on the information issued and the instrumentation and monitoring plan or as directed by the
SO, propose and submit the following to the SO for acceptance:
(a)
Select suitable make and model of the instrumentation for the Project.
(b)
Develop methods and details of the instrumentation installation and monitoring.
(c)
Propose suitable schedule for taking the monitoring reading and production of reporting records.
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1.4.2
Co-ordination with Other Works
Co-ordinate with other contractors who may carry out other works at the same time at the site.
Consider site access, space occupation, safety and safeguarding of adjoining properties and each
others works.
1.4.3
Existing Services Affected by the Works
Refer to preliminaries and conditions of contract for the requirements to deal with existing services
affected by the Works.
1.4.4
Protection and Maintenance of Instruments
Take all necessary precautions to protect the instruments and maintain the instruments in good
working order after commissioning.
For all instruments which project through and above the ground, take special precautions to provide
protection from vehicles and plant, including substantial and readily visible barriers at a distance of
750 mm around each instrument. Heavy compaction equipment shall not approach within 1.5 m of
projecting instruments.
Damaged instruments shall be replaced or repaired within 7 days unless otherwise agreed by the SO.
1.4.5
Labelling and Marking of Instruments
Establish and agree with the SO on a reference system for all instruments prior to installation, for easy
retrieval of data for any particular location.
Label all instruments with their reference number at the location where readings or measurements
are taken. The labelling shall be permanent using a method or material to be agreed on with the SO.
Link with QR code to a secure central database for documentation and information on all
instruments, readings and data.
1.4.6
Quality Control Plan
Submit and work to a quality control plan as agreed with the SO. Refer to the G01- 010:Clause:1.4.7.
1.4.7
Specialist Personnel
1.4.7.1
Borehole Installation
Engage qualified crew of not less than 2 men for the SOs acceptance for the operation of each
boring or drilling rig.
Engage qualified personnel for the SOs acceptance for every 2 drilling or boring rigs to supervise all
drilling works and to accurately record all drilling/boring and testing.
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1.4.7.2
Registered Land Surveyor
Engage a Registered Land Surveyor for surveying of settlement of the ground surface, roads, drains,
buildings, and other structures.
1.4.7.3
Instrumentation Installer
Engage qualified and suitably experienced personnel with the SOs acceptance to install and record
readings for all the instruments.
1.4.7.4
Instrumentation Specialist
Engage at least one Instrumentation Specialist with the SOs acceptance to co-ordinate all
instrumentation and monitoring works, including submission of method statements, calibration,
installation, data acquisition processing and verification, and presentation and reporting of
instrumentation and monitoring results. The Instrumentation Specialist shall be qualified with relevant
experience in the installation and monitoring of instruments, database management and
interpretation of instrumentation results for geotechnical and structural engineering purposes.
Evidence of experience, including curricula vitae (CVs) and records of previous similar works
undertaken shall be provided to the SO.
S1.4.8
Safety
Provide safety precautions to comply with all current legislation and regulations, notably:
a. Building Control Regulations
b. Code of Practice for Traffic Control at Work Zone
c. Factories (Building Operations and Works of Engineering Construction) Regulations
d. Factories Act
e. SS CP 79 Safety management system for construction worksites
For works within LTA Railway Protection Zone, ensure the works comply fully with Code of Practice for Railway
Protection.
2
PERFORMANCE REQUIREMENTS
2.1
Quality of Instrumentation
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2.1.1
General
Provide instruments and measuring devices manufactured by companies with established standards and
proven experience in the field of construction or geotechnical instrumentation.
Engage materials, designs and construction of such quality to provide robust, corrosion and vibration
resistant instruments. Use only reliable instruments with a satisfactory proven working life and are fully
functional through the duration of the Works.
The accuracy and dependability of the equipment shall not be significantly affected by changes in
temperature, humidity, stray currents or contaminants that may be encountered.
2.1.2
Survey Equipment
All surveying equipment used in conjunction with the monitoring of instrumentation, including measuring
tapes, precise levels, theodolites, digital levels and Total Station that combines Electronic Distance
Measurement Equipment with a digital theodolite and electronic data recording, shall be maintained
and calibrated as required by the manufacturers. Certificates of calibration for all equipment shall be
submitted and approved by the SO prior to carrying out the field work.
2.1.3
Electrical Interference
Ensure that electrical instrumentation is not adversely affected by other temporary or permanent
electrical services and equipment, and does not affect any other services, activities or equipment
within or adjacent to the Works. Where transformers are used, they shall have safety cut-out
devices to guard against overheating.
2.1.4
Stabilising Electronic Readout Devices
All electronic readout devices and transducers shall be shaded from direct sunlight during use.
Probes which are used inside access tubes shall be placed inside the tube and allowed to come to
a stable temperature for at least 10 minutes before use. Zero or starting values shall only be
taken after temperature stabilisation is complete.
2.2
Field Measurements and Monitoring
Instrumentation, measurements and monitoring shall be in accordance with BS ISO 18674 for the
performance monitoring of the ground, of structures interacting with the ground, of geotechnical fills,
and of geotechnical works as part of the geotechnical investigation and testing according to SS EN
1997-1 and SS EN 1997-2.
3
MATERIAL/EQUIPMENT
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3.1
Schedule of Instrumentation
Provide for SOs acceptance a schedule of instrumentation for the instruments tabulated in Table 1
below - showing instrument types, quantities, locations, minimum frequency of reading and duration
of reading; and detailed information in drawings or plans where practicable.
Carry out instrumentation and monitoring works as per schedule and as indicated in the drawings or as
directed by the SO.
Table 1. Instruments for schedule of instrumentation
3.2
.
Instruments (if applicable)
1.
Inclinometer (manual read)
2.
In-place inclinometers (remote read)
3.
Magnetic extensometers
4.
Rod extensometers
5.
Tape extensometers
6.
Deep levelling datum
7.
Levels / settlement marker
8.
Piezometers: Casagrande
9.
Piezometers: Vibrating wire
10.
Vibration monitors
11.
Settlement Markers
12.
Tell-tales
13.
Reflector targets
14.
Temperature sensors
15.
Strain gauges
Instrumentation and monitoring plan
An instrumentation and monitoring plan endorsed by the instrumentation specialists, and qualified,
competent and experienced PE, and Registered Surveyor (for drawing information containing
coordinates and Reduced Levels) to be submitted and approved by the SO shall contain at least the
following, where applicable:
(a)
Layout and location of neighbouring structures in relation to the underground building works.
(b)
Numbers, types, locations, details and other particulars of instruments for monitoring forces and movement
of structural elements, building and ground movements, and variations in the groundwater or piezometric
levels.
(c)
Frequency and duration of monitoring.
(d)
Allowable ground or building movement limits.
(e)
Allowable vibration limits.
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(f)
Long-term instrumentation, monitoring and maintenance requirements.
3.3
Remote Data Acquisition
3.3.1
Remote Data Acquisition System
3.3.1.1
Overall system
Propose for the SOs acceptance on the provision of remote data acquisition to be undertaken for
the Works, detailing the equipment types, locations, database and its acquisition, storage,
maintenance and retrieval system. Show information in drawings where practical and as appropriate.
Use of readout boxes for remote readout.
3.3.1.2
Remote readout facilities
All electrical measuring devices shall be capable of being read remotely using portable readout
units connected via readout boxes. Supply readout units together with leads for plugging into
the measuring device and readout boxes.
3.3.1.3
Instrument range
Readout boxes shall be capable of being placed up to 200 m from their associated instrumentation
or transducers with the specified accuracy of the instrumentation maintained.
3.3.1.4
Remote readout cover boxes
Readout cover boxes shall be made of robust water-resistant metal construction with lockable sealed
doors. Ensure all cable entries to the cover boxes are through watertight glands.
3.3.1.5
Link to site office
Include modem link and connection for direct computer link to allow reading for all remotely read
instrumentation and make links to the site office(s) as directed by the SO.
Use readout unit devices with facilities for recording monitoring data directly onto tape or magnetic disc
for subsequent computer processing.
3.3.2
Logger Stations
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3.3.2.1
General
Use reliable and safe remote data collection systems with back-up facilities in the event of mains
power failure. Prove the reliability of the logger prior installation by demonstration and records of
previous works.
Use a flex outlet without switches for all loggers when connected to the mains electrical supply.
Do not use plug sockets.
3.3.2.2
Station Requirements
Logger stations shall be as follows:
3.3.3
(a)
Capable of reading all instrument types proposed for each structure.
(b)
Programmable to log data at any specified interval, including real-time.
(c)
Capable of accepting new instruments to extend or repair the proposed system.
(d)
Easily connected to an external computer by either a direct hard wire or modem link as agreed with the
SO.
(e)
Unaffected by external electrical influence and shall not affect other electrical equipment.
(f)
Safe: in the event of overheating or short circuiting, the device shall shut down.
(g)
Logger stations shall collect the cabling from various remotely read instruments and from local terminal
boxes, so that monitoring can be conveniently carried out from a single position close to any instrumented
section.
Types of Cables
Use cabling and connectors that are robust, water resistant and corrosion resistant for instrumentation.
Use only low smoke zero halon cabling for all cables, which is durable and suitable for the proposed
locations in the Works.
Use items that are extinguishable non-metallic and emit no toxic fumes in the event of fire.
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3.4
Boreholes for Instruments
Boreholes for instruments shall be drilled and formed by an approved method that provides a clean and
stable hole of the required diameter to the correct depth for the installation of the instruments.
Boreholes shall be cased to full depth unless strata are sufficiently competent for the boreholes
to be stable under dry conditions.
Clean water is required for the drilling and formation of the boreholes. Drilling mud or polymer additives
shall only be used with the approval of the SO. In the case of installation of piezometers, drilling mud
or polymer additives shall not be permitted.
During drilling, take care to ensure that minimum material is lost from outside the casing. Do not
allow surging of casing and minimise flushing of drilling water up the outside of the casing.
The method of forming boreholes, including the procedure for advancing casing, shall be submitted to
the SO for approval before commencement of the Works.
3.5
Grouting of Boreholes
Grouting is required for part or entire depth of all boreholes formed for the purpose of installation of
instruments.
The grout shall be of a bentonite-cement mixture to achieve an appropriate mix for the Site.
Conduct trials on different mixes of bentonite-cement to ascertain the relationship with strength. The
grout mix and the grouting method shall be submitted and approved by the SO.
3.6
Probe Inclinometer (Manual Read)
3.6.1
General
Inclinometers shall take the form of an access tube with 4 keyways in pairs at right angles. The
orientation of the keyways shall be parallel to and perpendicular to the orientation of any tunnel,
excavation, retaining walls or structures, or otherwise as accepted by the SO.
[Note 1: Construction tolerance in keyways would compromise accuracy in the B-B direction readings
when probe wheel is aligned in the A-A direction. If deformation in both directions of the keyways is
crucial, e.g. monitoring movement of a single pile, repeat readings taking in both directions by
aligning the probe wheels in each direction.]
3.6.2
Probe
The probe used to take measurements shall have the following features:
(a)
A wheelbase of 500 mm
(b)
A measurement range of 30°or greater from vertical
(c)
A resolution of 0.02 mm or greater per 500 mm with a repeatability of 0.003 degrees
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(d)
A minimum radius curve for retrieval of 2.2 m or less
(e)
A working temperature range of -20°C to +50°C or greater
(f)
A construction (externally) of stainless steel
[Note 1: The measurement shall be within the calibration range.]
3.6.3
Data Recorder
The inclinometer data recorder unit shall display the readings from the inclinometer probe on an
alphanumeric display. The readout unit shall be powered by a rechargeable battery with a minimum
life of 16 hours of continuous use or more between charges.
A backup battery shall be incorporated to keep data secure for a minimum of 72 hours on depletion of
primary power source. Signal shall be emitted to confirm power failure and confirm that the battery
pack is operative.
A suitable automatic battery charger shall be supplied with the readout unit.
Data recorder with a solid-state data storage unit shall have a minimum storage and retrieval capacity of
30,000 data points directly from the probe together with time of measurement.
The readout unit shall have the following features:
(a)
Scanning of stored data
(b)
Display of errors as readings are being obtained
(c)
Display of mean deviation and cumulative deviation of any one set of readings
(d)
Graphical display of displacement profile between any 2 sets of readings
(e)
Backlit LCD display
A calibration frame shall be supplied to enable the inclinometer calibration to be checked at vertical and
10 degrees either side of vertical.
3.6.4
System Accuracy
The system accuracy of the inclinometer shall be ±6 mm per 25 m of casing or better.
The inclinometer and logging system shall be capable of recording movements in both directions or
biaxial type.
Refer to specific standards or manufacturer’s specifications or guides, wherever possible, on
tolerances, characteristics, accuracy of instrumentation and monitoring for the acceptance of SO.
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978
Doc D.2/396
3.6.5
Calibration Device
Provide a calibration device with the instrument, which calibrates both the probe and the portable
readout unit for SOs acceptance.
3.7
In-place Inclinometers (Remote Read)
3.7.1
General
In-place inclinometer consists of one or more built-in for measurement of the inclination at specific
locations on a measuring line without removing the instrument.
3.7.2
Sensors
Resolution of each sensor shall be 0.04 mm per m or better and the measuring range to be at least
±10 degrees. The precision of the sensor shall be ±0.1 mm per m. The allowable maximum gauge
length (spacing between sensors) shall be no greater than 3 m.
The operating temperature range shall be from -20°C to 50°C and the compensated temperature
range to be from 0°C to 45°C.
3.7.3
Electrolevel System
Where specified, use an electrolevel inclinometer consisting of a waterproof sensor that is remotely
monitored using a computer data logging system. Use a datalogger capable of at least 14 daysâ
operation in the event of power failure.
3.7.4
System Accuracy
The inclinometer and logging system shall be capable of recording movements in both
directions (i.e. biaxial). The system accuracy of the inclinometer shall be ±6 mm over a depth of
25 m or better.
Refer to specific standards or manufacturer’s specifications or guides, wherever possible, on
tolerances, characteristics, accuracy of instrumentation and monitoring, for the acceptance of SO.
3.8
Extensometers
3.8.1
Magnetic Extensometers
3.8.1.1
General
Use magnetic extensometers in the form of a series of magnetic rings ("spider magnets") fixed into
a maximum 150 mm diameter borehole with plastic tubing of nominal 75 mm minimum internal
diameter, allowing access to magnetic points for the measurement of settlement.
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Doc D.2/397
3.8.1.2
Description
The magnetic extensometer shall consist of an access tube and a series of magnetic targets which are
free to slide up and down the outside of the tube, together with a datum magnet which is fixed to the
tube near its base. Reference shall be made to the top of the access tube which will need to be
measured by standard levelling techniques.
Unless otherwise agreed by the SO, the access tube shall be a rigid PVC tube with outside
diameter of 33.5 mm and inside diameter of 24.5 mm, with threaded ends that provide both an
internal and external flush coupling. A rigid PVC endcap shall be fixed to the lower end of the series
of tubes. All joints shall be sealed with a suitable PVC solvent cement.
Where required by the SO, compression/extension tubes shall be provided to allow axial movement
of access tubes to minimise distortion due to vertical strain. The tubes shall have threaded ends to
provide an internally and externally flush coupled joint. The smaller diameter end tubes are fitted with
"O" rings or equivalent, and are free to slide within the larger diameter central cylinder. The minimum
allowable compression and extension length shall not be smaller than 0.6 m and 1.0 m respectively.
3.8.1.3
System Precision
The system precision shall be ±1.0 mm.
Check that the reading system is reliable and requires minimal maintenance over the required
monitoring period. Thermal or other influences shall be negligible.
Refer to specific standards or manufacturer’s specifications or guides, wherever possible, on tolerances,
characteristics, accuracy of instrumentation and monitoring, for SOs acceptance.
3.8.2
Rod Extensometers
3.8.2.1
General
Use rod extensometers in the form of a rod anchored at the remote end of the borehole passing
into a plastic tube fixed in a reference collar at the open end of the hole.
3.8.2.2
System Accuracy
The measurement system shall have an overall accuracy of ±0.25 mm.
Refer to specific standards or manufacturer’s specifications or guides, wherever possible, on tolerances,
characteristics, accuracy of instrumentation and monitoring, for SOs acceptance.
S3.8.2.3
Restrictions on Rods
Install no more than six rods in a single hole with each rod of a different length so that displacements at various
borehole depths may be recorded.
Where more than six rods are required, prepare another borehole as close as possible to the initial hole and rods
set at alternate depths in each hole.
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Doc D.2/398
S3.8.2.4
Materials
Rods to be fabricated from stainless steel. The grade of steel rod shall suit the environment and duration of the
project. Make provision for threading the anchor points onto the rod.
S3.8.2.5
Measurement of Relative Movement
Measure relative movement between the end anchor and the reference collar by an automated measurement
device (an electrical transducer) registering on the free end of the rod and by manual means using a system to the
acceptance of the SO.
Extend the reading range beyond that of the measurement device by a range adjustment device fitted at the
reference collar.
S3.8.2.6
Measuring Head
Measuring head to be of design to allow manual readings to be taken.
Extensometers to be of design that make the measurement of both elongations and reductions in the length between
anchorage point and measuring head possible.
Undertake remote reading using the electrical transducers linked to a logger station, with an overall accuracy of
+0.25 mm and with a measuring range of 150 mm. In the event that movements potentially exceed 150 mm, make
adjustment to allow continued monitoring. Use transducers that are waterproof to 15bar.
Cabling to the terminal box to be capable of accepting up to six extensometers from each hole. Provide a battery
operated digital readout device capable of reading to the required overall accuracy.
3.8.3
Tape Extensometers
3.8.3.1
General
Use a tape extensometer comprising a steel tape, a portable measuring instrument with metric
dial calliper and a pair of anchor clips.
3.8.3.2
System Accuracy
Use a tape extensometer that is capable of being read to ±0.15 mm and have a range of 20
m. Demonstrate a repeatability of reading to ±0.15 mm prior to use.
Refer to specific standards or manufacturer’s specifications or guides, wherever possible, on
tolerances, characteristics, accuracy of instrumentation and monitoring, to the acceptance of SO.
TS 329/1065
978
Doc D.2/399
3.8.4
High Precision Optical 3D Measuring Method
Propose for the SOs acceptance on the use and installation of Optical 3D displacement measuring
method using purpose-built glass prism (surveying) reflectors with high precision Total Station that
combines Electronic Distance Measurement with a digital theodolite and electronic data recording, to
produce high accuracy three-dimensional coordinates, and compute angles and distances between
the points under survey.
[Note 1: By repeated measurements of the 3D measuring points, time-dependent diagrams that
describe the convergence of tunnel wall deformation behaviour of measuring points with high
precision shall be produced.]
3.8.4.1
Total Station Measurement Accuracy
The Total Station measurement shall have the following measurement accuracy:
3.9
S3.9
(a)
angular accuracy of 1.0 arc second and
(b)
distance measurement accuracy at ± 1 mm + 2 parts per million (ppm).
Not In Use
Deep Levelling Datum
Deep Levelling Datum shall comprise a 25 mm galvanised steel rod cast into a 250 mm diameter
grout filled steel casing positioned within a 300 mm diameter steel casing.
Fill the annulus between the two casings with grease. The top of the 25 mm steel rod shall be domed and centre
punched.
3.10
Levels
3.10.1
Standard Levelling
Use a basic optical level of an approved make and specification with a single measurement precision of
±1 mm with a standard measuring staff.
The accuracy of results here should be within ±3 mm.
Refer to specific standards or manufacturer’s specifications or guides, wherever possible, on tolerances,
characteristics, accuracy of instrumentation and monitoring, to acceptance of SO.
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978
Doc D.2/400
3.10.2
Automatic (optical) level
Use a basic automatic (optical) level that consists of a micrometer attachment with a valid calibration
certificate and sectional levelling staves to conduct double-run levelling with measurement precision
within ±2 mm.
Final accuracy of instrumentation and monitoring subject to acceptance of SO.
Refer to Land Surveyors Board (LSB) Directives on Engineering & Hydrographic Survey Practices for
full details on levelling survey’s standard and accuracy order.
3.10.3
Precise Levelling
Where more accurate levelling with submillimetre accuracy is required, propose for the SOs
acceptance on the provision of precise-levelling instruments and methodology, including the use of
robust tripods, that have the accuracy with high precision necessary for the purpose of preciselevelling measurements.
Use a high precision automatic or digital level coupled with invar staves for submillimetre accuracy
results. Precise levelling techniques shall be employed in the double-run survey with equidistance
back and fore sight at all instruments set up. Levelling sights shall not exceed 30 m.
Refer to the Refer to Land Surveyors Board (LSB) Directives on Engineering & Hydrographic Survey
Practices for more details.
3.11
Piezometers
3.11.1
General
Piezometers are used for measuring pore pressures in ground. They are the pressure transducers
that are installed beneath the ground to measure the sub-surface piezometric level within
groundwater level, soil, or rock.
Type and specification of piezometer transducers shall be according to manufacturer’s recommendation
and with the SOs acceptance.
3.11.2
Casagrande Piezometers
3.11.2.1
Tube
The Casagrande piezometer (or open standpipe) consists of a riser pipe that shall be of
unplasticised polyvinylchloride (uPVC) of nominal diameter 19 mm and supplied in lengths of 3 m.
The tube shall be connected at its lower end by suitable PVC fitting to a filter tip.
The tube shall be connected at its lower end by suitable PVC fitting to a piezometer tip.
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Doc D.2/401
3.11.2.2
Tip
Porous ceramic element or rigid uPVC perforated pipe having an expanded polystyrene lining moulded
to form an inner tube of not less than 13 mm bore retained in position by a moulded flange as
approved, with minimum length of 150 mm and minimum diameter 35 mm, protected by uPVC
fittings. Permeability shall be approximately 3 x 10-4 m/s.
If permeability test is to be carried out in piezometer, the filter tip shall be increased to at least 900 mm
in length.
3.11.2.3
Filter
The tip shall be placed in a sand cell consisting of clean sand between grading limits of 600 and 1
200 microns. A bentonite seal shall be placed above the sand cell to isolate the pore water
pressure at the tip.
3.11.3
Vibrating Wire Piezometers
3.11.3.1
Tip
Vibrating Wire Piezometers is a pressure transducer that can be sealed in a borehole or embedded
in fill. Choose the type of tip to suit the expected maximum groundwater pressure and the
characteristics of the surrounding ground. Use only piezometers with high air-entry tips.
3.11.3.2
S3.11.3.2
Not In Use
Push-in vibrating wire piezometers
Where accepted by the SO on the use of "push-in" vibrating wire piezometers, a mandrel of not less than
0.5 m in length is required. In such cases, there will be no requirement for a sand cell. Backfill using bentonite and
grout as directed.
The combined accuracy of the instrument and the readout device to be within ±1.0 % of the true pressure. Use
instrument capable of measuring pressures up to 15bar.
3.11.3.3
System Accuracy
The combined accuracy of the instrument and the readout device to be within 1.0% of the true
pressure.
Use instrument capable of measuring pressures up to 15 bar.
Refer to specific standards or manufacturer’s specifications or guides, wherever possible, on tolerances,
characteristics, accuracy of instrumentation and monitoring, for the SOs acceptance.
[Note 1: Pneumatic Piezometers are not used.]
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978
Doc D.2/402
3.12
Vibration Monitors
3.12.1
Description
Vibration monitors shall be capable of taking and recording velocities on a continuous basis in 3
perpendicular directions. The monitors shall be capable of registering vibrations of magnitude and
frequencies that reflect the normal construction activities on site.
Type and specification of vibration monitors shall be according to manufacturer’s recommendation and
with the SOs acceptance.
3.13
Settlement Markers
3.13.1
Description
Provide settlement markers with drive-in or cast-in survey nails for SOs acceptance and at agreed
locations. Unless otherwise directed by the SO, levels of the top of the rods of settlement markers
shall be measured using precise levelling and the datum used shall require only one set up of the
level, and levelling shall be closed back to the datum.
[Note 1: Install ground settlement markers on hard ground such as concrete slab, pavement or road
surface, with nails of 50 mm in length with plastic helmet. For markers in soft ground, drive in or cast
a steel rod of diameter 12 mm or larger into soft ground within a pipe-sleeve, with a protective
cover.
Note 2: Ground settlement markers shall be measured by means of precise levelling with invar
staves for the establishment of initial or base reading. For subsequent periodic settlement
reading, sectional, barcoded levelling staves shall be sufficient.]
3.13.2
System Accuracy
See Section C02-050:Clause:3.10.
3.14
Building Settlement Markers
TS 333/1065
978
Doc D.2/403
3.14.1
Description
Building settlement markers or levelling studs shall be measured by means of precise levelling.
Building settlement markers shall be of stainless steel, Grade 316 S13 or equivalent. The heads of
the levelling studs mounted walls are required to be easily levelled without the studs being vulnerable
to damage. All surfaces of levelling studs in contact with levelling rods and staves during
measurements shall be clean, and proper access shall be provided to the crown levelling studs for
cleaning during the survey.
Building settlement markers or levelling studs, made up of stainless-steel anchor with bolt (25 mm
length) shall be used for monitoring structural elements such as wall or column, where drilling is
allowed. If drilling in structural elements is not allowed, install barcoded aluminium levelling strip that
allows for heat expansion and contraction, for the measuring point on the wall.
Refer to Land Surveyors Board (LSB) Directives on Engineering & Hydrographic Survey Practices.
[Note 1: Building settlement markers or levelling studs shall be measured by means of precise
levelling for establishing the initial (base) reading. For subsequent periodic settlement reading, a
normal barcoded levelling staff shall be sufficient.]
3.14.2
System Accuracy
Precise levelling survey shall fall in the 1st order levelling methodology, where the levelling
instrument must have at least ±0.4 mm distance accuracy at 1km double run levelling loop, to
achieve at ±2 mm âK, where K is distance in kilometre.
Refer to Land Surveyors Board (LSB) Directives on Engineering & Hydrographic Survey Practices.
3.15
Tiltmeters
3.15.1
Description
The tiltmeter system shall include tilt plates, the portable tiltmeter and a readout unit.
3.15.2
Tilt plates
Tilt plates shall be mounted on the structures, and correctly aligned to the orientation of
measurement, at locations indicated in the drawings and agreed with the SO. The tilt plates shall be
securely bonded using an approved rapid setting epoxy adhesive compound or screwed to the
surface of the structure, and shall be dimensionally stable and weather resistant.
Tiltmeter range: ±53 degrees from vertical.
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Doc D.2/404
3.15.3
Portable Tiltmeter
The portable tiltmeter shall be in metric unit system and housed in a rugged frame with precise
machined surfaces to facilitate accurate positioning on horizontally or vertically mounted tilt
plate.
3.15.4
Readout Unit
The readout unit shall be suitable for the tiltmeter and shall be of a rugged, weather-proof design with
easy to read display and rechargeable battery or equivalent. A sufficient length of jumper cable shall be
provided for connecting the tiltmeter to the readout unit.
The tiltmeter shall conform to the following criteria:
Table 2. Tiltmeter conformance criteria
Metric
Criteria
Range
30 from vertical
Resolution
8 arc seconds
Temperature Coefficient
(0.05% of reading + 5 arc seconds)/ C
Refer to specific standards or manufacturer’s specifications or guides, wherever possible, on
tolerances, characteristics, accuracy of instrumentation and monitoring, for the acceptance of SO.
3.15.5
Measurement
Tilt reading shall be taken by positioning the tiltmeter on the tilt plate and connecting the tiltmeter
to the readout unit. At least 2 readings shall be taken by rotating the tiltmeter at 180° for each
reading.
3.16
Load Cell
3.16.1
Description
Install load cells at locations indicated in the drawings and agreed with the SO. Vibrating wire load cell
or any other approved type shall be water-resistant and made of corrosion-free material or made
from aluminium alloy for field use.
3.16.2
Use with Ground Anchors
For use with ground anchors, the load cells shall be hollow centrally with inner diameter not less than
100 mm and the load cell measurement range shall be at least 2.5 times the working load of the
ground anchors. The load cell shall be installed before the prestressing and locking of ground anchor
load. The load cell shall be placed centrally to reduce errors that result from load misalignment and
off-centre loading. Initial cell readout must be taken immediately after the installation is complete.
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978
Doc D.2/405
3.16.3
System Accuracy
Unless otherwise agreed by the SO, load cells are required to be able to read in the expected
measurement range of load to be monitored plus 50% of the maximum load.
Refer to specific standards or manufacturer’s specifications or guides, wherever possible, on
tolerances, characteristics, accuracy of instrumentation and monitoring, to the acceptance of SO.
3.16.4
Measurement
Load cells are required to be connected to a data logger to allow automated readings to be taken
at the specified frequency as directed by the SO. Shielding of the equipment is required to avoid
electronic magnetic interference distorting measurement readings.
3.17
Tell-Tales
3.17.1
Description
Tell-Tales shall generally comprise 2 clear plastic overlapping plates, one marked with a millimetre
scale, the other with a crosshair marking to allow reading on 2 axes.
If the position of the Tell-Tale is out of general sight, it shall be readable without obstruction.
3.17.2
System Accuracy
Tell-Tales shall have an accuracy of ±1 mm, with a range of ±20 mm.
Refer to specific standards or manufacturer’s specifications or guides, wherever possible, on
tolerances, characteristics, accuracy of instrumentation and monitoring, to the acceptance of SO.
3.17.3
Measurement
Take readings in both directions of separation in a consistent manner by the same personnel. Inform SO
in cases where out-of-plane movement is observed that is distorting the in-plane movements and the
corrective action taken.
3.18
Reflector Targets
3.18.1
Description
Install prism reflector targets at the locations shown in the drawings and of the target type as agreed by
the SO.
Targets shall be durable, not damaged by rain and fixed and shall not be disturbed by vibration.
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978
Doc D.2/406
3.18.2
System Accuracy
Unless otherwise agreed by the SO, targets shall provide an overall measurement accuracy of ±1
mm with readings taken from high precision Total Station which has an angular accuracy of 1.0
arc second and distance measurement accuracy at ±1 mm + 2ppm.
Refer to specific standards or manufacturer’s specifications or guides, wherever possible, on tolerances,
characteristics, accuracy of instrumentation and monitoring, for the SOs acceptance.
Unless otherwise agreed by the SO, targets shall provide an overall measurement accuracy of ±1
mm
3.18.3
Measurement
Targets shall be measured manually or automatically at the specified frequency. The position of
targets on site shall be such that line of sight is maintained at all times.
3.19
Temperature Sensors
3.19.1
Description
Temperature sensors shall be of a resistance temperature detector or thermocouple type as directed by
the SO.
3.19.2
S3.19.2
Not In Use
System Accuracy
Ensure the working range of the sensors is appropriate to the expected temperature measurement
range in the field and to be at -40°C to 60°C with an accuracy of ±1 C.
Refer to specific standards or manufacturer’s specifications or guides, wherever possible, on tolerances,
characteristics, accuracy of instrumentation and monitoring, to SO for acceptance.
3.19.3
Measurement
All sensors shall be capable of being remotely monitored and the data downloaded to a computer in a
file format agreed by the SO.
3.20
Strain Gauges
3.20.1
Description
Securely install strain gauges at the locations shown in the drawings and of an appropriate type to
be agreed by the SO.
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978
Doc D.2/407
3.20.2
System Accuracy
Vibrating wire strain gauges shall have the following characteristics:
Table 3. Vibrating wire strain gauges characteristics
Metric
Characteristics
Strain range
2500 x 10-6 m/m
Accuracy
±3.0 x10-6 m/m
Resolution
0.5 x 10-6 m/m
Response time
not more than 10 secs.
Refer to specific standards or manufacturer’s specifications or guides, wherever possible, on
tolerances, characteristics, accuracy of instrumentation and monitoring, to the acceptance of SO.
3.20.3
Signal Cable
Shield signal cable with flexible polyurethane jacket. Temperature-rated minimum ranges shall be
from 0°C to 80°C and to be compatible with the environment in which the gauges are installed.
3.20.4
Measurement
Strain gauges are required to be connected to a data logger to allow automated readings to be
taken at the specified frequency. Shielding of the equipment is required to avoid electronic magnetic
interference distorting measurement readings.
4
WORKMANSHIP
4.1
General
4.1.1
Instrument Maintenance
Maintain all instruments, including readout and data loggers, required for monitoring in a satisfactory
working order for the duration of the monitoring programme.
4.1.2
Storage
Securely store all equipment and installation accessories prior to installation where they will not suffer
physical damage or damage arising from excessive moisture, extremes of temperature or any
adverse conditions.
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Doc D.2/408
4.1.3
Installation and Testing
Install and test all equipment, including connections and fittings in accordance with the manufacturer’s
recommendations. Reconfirm the depth of installation of underground instrumentation with the SO based
on the soil profile encountered in the borehole for the purpose.
4.1.4
Grouting
Do not backfill boreholes with soil arisings, unless otherwise agreed with the SO.
Backfill all boreholes with bentonite-cement grout, with standpipes and piezometers together with their
response zones installed at the depths specified, or as directed by the SO.
Introduce the grout using a tremie pipe which is kept below the surface of the grout as filling proceeds.
Agree the methods to be used where ground conditions make normal grouting impracticable. Leave
the area in a clean and tidy condition.
Refer to Section C02-010:Clause:3.2 for requirement of bentonite-cement grout materials.
4.1.5
Testing
Undertake testing as necessary to ensure satisfactory functioning of the equipment at each stage of
the installation.
Report any instruments found to be malfunctioning at any time to the SO within 24 hours of the fault
being identified and replace at the earliest opportunity.
4.1.6
Fixing and Protection
4.1.6.1
Fixing Details
Securely fix all instruments and adequately protect their terminations, including any attendant wiring and
terminal panels, against mechanical damage and ingress of water and dirt.
Fix the equipment such that it is capable of resisting vandalism and adverse climatic conditions at
surface locations. In addition, protect all instruments by hoarding or barriers as directed.
Tag all external visible protective covers to equipment using aluminium rigid nameplates of minimum
size 2 500 mm2, SWG 24 or similar to the acceptance of the SO, identifying the following:
(a)
Project title and contract number
(b)
Equipment reference number
(c)
A contact name and contact telephone number
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978
Doc D.2/409
4.1.6.2
Protection Details
Provide as detailed in a method statement, protection details for inclinometers, piezometers,
extensometers and settlement points, with the SOs acceptance. Develop alternatives if necessary, to
fit in with site constraints and further improve protection to the instruments.
Protection systems for other instruments shall also be developed where necessary. These protection
systems shall provide a similar or better level of protection as that provided by the systems shown in the
drawings.
4.1.6.3
Prevention of Damage
Take all sensible measures to prevent damage to the instruments and ancillary equipment during
handling, installation and subsequent operations. Replace any instrument and/or ancillary equipment
damaged during handling, installation or subsequent operation immediately.
Snake or coil cabling and tubing to provide sufficient slack to accommodate potential ground movement.
4.1.7
Instrument Reference System
Establish a logical reference system for all the instrumentation equipment prior to installation and to the
satisfaction of the SO, so records for any particular location can easily be recovered for
interpretation or review.
4.1.8
Remote Readout
4.1.8.1
Location of Readout Boxes
Position readout boxes for ease of access and protect from damage during construction. Propose
locations unless shown otherwise in the drawings for acceptance by the SO.
4.1.8.2
Location of Logger Stations
Position logger stations for ease of access and protect from damage during construction. Propose
locations unless shown otherwise in the drawings for acceptance by the SO.
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978
Doc D.2/410
4.1.8.3
Cable Fixing and Identification
Fix cabling for instrumentation neatly and securely to appropriate cable trays which in turn shall be
securely fixed to the structure. Tag all cabling with an appropriate reference, identifying the
instrument to which it is attached.
Protect cables in galvanised pipes from ground level to one metre below cut-off level. In addition,
clearly label the cables at 0.5 m interval within the protected length. Where possible, use colour-coded
cables for the purpose of identification.
Use single length cable for newly installed vibrating wire piezometer. Do not allow splicing unless
otherwise agreed. When splicing is allowed, ensure water tightness of the splices in the event where
the cables are damaged and need to be spliced.
4.1.8.4
Identification of Cables
Tag each individual cable at least at the instrument end connection and at the logger connection
identifying that cable. Maintain a schedule showing all cables and their respective connections.
4.2
Instrument Reading and Records
4.2.1
Schedule of Monitoring
Submit a proposed schedule of instrument monitoring readings for the acceptance of the SO. Comply
with the minimum frequency and duration of readings for each instrument as provided in Section C02050:Clause:3.1.
Vary the frequency depending upon the stage of the Works as provided in Section C02050:Clause:3.1 or as agreed by the SO. In some cases as directed by the SO, continuous logging is
required.
Increase the monitoring frequency at any stage as directed by the SO if the performance of the Works
being monitored does not perform as predicted, or the Works are likely to cause adverse effects on
the adjacent properties if proceeding further.
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Doc D.2/411
4.2.2
Ground Movements and Vibrations
When planning for suitable methods and schedule for monitoring, take account on the limits on
movements and levels of vibration for the adjacent buildings and those indicated in drawings or as
directed by the SO.
When planning for suitable methods and schedule for the monitoring, take account on the general
restrictions on movements and levels of vibration for the adjacent buildings as set out below, unless
otherwise agreed by the SO or regulated by statutory requirements or indicated in the respective
sections:
Table 3: Restrictions on movements and levels of vibration for adjacent buildings
Building
4.2.3
Limits on ground movement (mm)
Limits on level of vibration
(mm/s)
Horizontal
Vertical (Settlement)
Alert
Worksuspension
Alert
Work- suspension
Alert
Work-suspension
.
.
.
.
.
.
.
.
.
.
.
.
.
.
Methods of Taking Readings
Do not use any form of instrument which uses electrical resistance methods for taking readings
unless otherwise agreed.
4.2.4
Initial Readings
Read all instruments as soon as possible after installation and at least once per day for a period
of 2 weeks thereafter until readings have stabilised.
Where instruments appear not to have stabilised, for example exhibiting a continued drift in the
readings, the cause shall be identified, and the fault rectified, and a new set of readings provided.
When all instruments are showing consistent results for a period of 1 week, readings shall be averaged
to provide a datum or base reading. The base readings shall be established before construction work
starts.
4.2.5
Site Conditions
When recording instrumentation readings, record all site conditions that may affect the results,
including temperature and humidity readings. (Suitable supplementary instrumentation shall be
installed to provide these data.)
Record also the instrument type, location reference, datum and time of reading, personnel carrying
out the readings and measuring instrument or readout unit reference.
Record any observations of unusual conditions that could influence the instrumentation or the structure.
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Doc D.2/412
4.2.6
Reading Records
After installation, the functioning of each instrument shall be demonstrated to the SO, including
the recording of measured values using the appropriate readout device.
As part of the commissioning, a set of datum readings will be established in accordance with Section
C02-050:Clause:4.2.4.
In cases where instruments are installed during construction, establish base or datum readings as
quickly as possible by taking at least 3 separate sets of measurements and compare the results.
These results shall be used to provide base datum in a manner to be agreed with the SO for
monitoring.
Record instrument readings in accepted format for subsequent processing by computer. Make
corrections for temperature difference or other factors as appropriate shall be made, but
uncorrected data shall also be stored and made available on request.
Produce plots of deformation, stress, raw data readings against time together with plots of temperature
and humidity, or other data as directed when relevant.
4.2.7
Consistency of Instrument Use
Use the same recording devices, e.g. tape extensometers, level, EDM and Theodolite, etc. at any
given location throughout the monitoring programme.
If this becomes impractical, take new datum readings immediately with a replacement instrument, and
use the new instrument for future readings.
4.2.8
Consistency of Readings
Readings shall be taken by the same personnel to maintain consistency. If personnel need to be
replaced for any reason, take a series of 3 duplicate readings by both the outgoing person and the
replacement.
4.2.9
Consistency of Location
Should a monitoring location become unavailable, read the instrument previously read from this point
from an alternative point, as soon as practicable after the location becomes unavailable. Use this
for all subsequent readings.
Include a reference to such changes on the summary plots.
4.3
Inclinometers (Manual Read)
4.3.1
General
All inclinometer tubing and instrumentation shall be resistant to aggressive/adverse substances in
the ground and shall conform to the requirements for sub-surface installations.
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4.3.2
Tubing
Provide the tubing with appropriate couplings for joining tube lengths to the required borehole length.
Inclinometer tube to be slotted plastic of 75 mm internal diameter that is pre-grouted into a minimum
100 mm diameter borehole, or a steel pipe of at least 150 mm when placed in a structural element.
Tubing to be of uniform section and free of twist in manufacture and shall not twist during
installation. The spiral twisting of the keyways shall not exceed 0.75 degrees per metre length of the
tubing. The grooves in each section of the tube shall be accurately aligned using the alignment
tool supplied before fixing the joint.
Adequately fix and seal the cap and coupling joints so that the tube is grout and dirt.
Lower the joined and sealed tubing into the borehole and grout the annulus using a bentonitecement grout tremied to the bottom of the hole. Fix the tubing from rotation while being lowered.
After assembly joints and rivets shall be sealed with mastic tape and wrapped with biaxially oriented
polypropylene tape or other means approved by the SO. The bottom section of the tube shall be
fitted with a protective cap riveted in a similar manner to the tube joints.
4.3.3
S4.3.3
Not In Use
Installation
Insert a slotted plastic inclinometer tube of minimum 60mm internal diameter into a minimum 100mm diameter
borehole or a steel duct of at least 150 mm cast into any pile or wall.
Withdraw any temporary casing used during boring/drilling at the time of grouting the inclinometer tubing. Embed
the toe of inclinometer into hard stratum below which the ground movement is negligible. Prior to installation,
propose the installation level for acceptance of the SO.
4.3.4
Probe Location
Provide suitable means of measuring the position of the probe down the borehole to an accuracy of
±10 mm from a reference point at the top of the borehole.
Establish the co-ordinate of the reference point prior to all readings by surveying from a suitable stable
benchmark.
4.3.5
Extension of Inclinometers
Where inclinometers already exist and are to be extended, the new tubing shall match the existing
tubing.
During earthworks operations, extend the inclinometer tubes in lengths and ahead of the fill to a
manner accepted by the SO.
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4.3.6
Stability and Gain Check
Check stability and gain of the reading system at weekly intervals unless otherwise agreed, and
provide results to the SO.
4.3.7
Spiral and Inclination Check
Carry out spiral and inclination check prior to establishing the datum reading.
4.3.8
Inclinometer in a structural element.
Where an inclinometer is placed in a structural element, a secondary or auxiliary guide pipe or
casing should be installed adjacent to the main guide pipe or casing to provide redundancy particularly
in situations where measurements are crucial.
Where an inclinometer is placed in a structural element such as embedded retaining wall or pile, the
toe of the inclinometer access tube shall be at least 1.5 m below the toe of the structural element
or to a depth where the stratum of SPT N ≥100 whichever is deeper.
The annulus between the inclinometer access tube and the pipe casing in the structural element
shall be grouted. Unless otherwise agreed by the SO, the grout shall have a minimum
compressive strength measured on 100 mm cubes of 20 N/mm2 at 3 days and 35 N/mm2 at 28
days. The initial grout shall be completed in one operation until all water and diluted grout have
been expelled from the top of the borehole.
[Note 1: Depending on excavation depth, toe of retaining structure needs not always be founded
in/ near layer with SPT N>100. Under such ground conditions and subject to the SOs acceptance,
the toe of the inclinometer access tube shall be at least 1.5 m below the toe of the structural
element or to a depth of at least 1 m into a stratum of SPT N ≥ 50 whichever is deeper.]
4.3.9
Ground Level Installation
At the final ground level fit the inclinometer tubing with a removable cap within a lockable vandalproof cover set in a concrete surround.
Cover and surround details shall be to the acceptance of the SO.
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4.3.10
Measurement
Immediately before or after taking a series of readings, the level and position of the top of the access
tube shall be measured by standard levelling techniques.
Before passing the probe down the access tube, a dummy probe shall be lowered to the base of the
tube and pulled up to check for obstructions or constrictions.
When taking readings, insert the inclinometer probe in the tube. Lower the probe to the base where
time is given to adjust to environmental conditions. The probe is then raised taking measurements
every 0.5 m until reaching the top. The inclinometer shall travel along the whole length of the tube
with wheels engaged in each pair of the keyways in turn to obtain deformation measurements in
both directions.
The measurements shall be stored in the data logger that displays the checksum following a complete
set of readings to check for errors.
Repeat the procedure on the opposite face, following the manufacturer's method and sign convention.
4.4
In-place Inclinometers (Remote Read)
4.4.1
General
Ensure all inclinometer tubing and instrumentation shall be resistant to aggressive/adverse substances
in the ground and conform to the requirements for sub-surface installations.
Ensure that the in-place inclinometer is capable of providing continuous, unattended monitoring data.
4.4.2
S4.4.2
Not In Use
Installation
Insert a slotted plastic inclinometer tube of 75 mm internal diameter into a minimum 100mm diameter borehole or a
steel duct of at least 150 mm cast into any pile or wall.
Any temporary casing used during boring/drilling shall be withdrawn at the time of grouting the inclinometer tubing.
Embed the toe of inclinometer into hard stratum below which the ground movement is negligible.
Prior to installation, propose the installation level for the acceptance of the SO.
4.4.3
Tubing
Provide the tubing with appropriate couplings for joining tube lengths to the required borehole length.
Adequately fix and seal the cap and coupling joints so that the tube is grout- and dirttight.
Lower the joined and sealed tubing into the borehole and grout the annulus using a bentonitecement grout tremie to the bottom of the hole. Fix the tubing from rotation while being lowered.
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4.4.4
Not In Use
S4.4.4
Sensor
Install the biaxial electrolevels at spacing acceptable to the SO and connect with a rod to give a fixed gauge
length. At the end of the sensor and the gauge extension, fit a spring-loaded wheel assembly. Do not use sensors
mounted on sleds. Check that the spacing of sensor is no greater than 3 m.
4.4.5
Stability and Gain Check
Check stability and gain of the reading system at weekly intervals by means of 3 "dummy" electrolevels
using precise resistors and provide results to the SO.
4.4.6
Spiral and Inclination Check
Carry out spiral and inclination check prior to establishing the datum reading.
4.4.7
Ground Level Installation
At the final ground level fit the inclinometer tubing with a removable cap within a lockable vandalproof cover set in a concrete surround.
Cover and surround details shall be to the acceptance of the SO.
4.5
Extensometers
4.5.1
Magnetic Inclinometer Extensometers
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4.5.1.1
Installation
Set a datum magnetic ring at approximately 2 m above the base of the inclinometer tubing and also
within the instrument chamber base, located at the top of the borehole.
The tubes and magnets shall be assembled prior to installation in such a way that the magnets
remain in the correct position in relation to the tube. The tube shall be coated with a thick grease over
its upper part where the tube passes through compressible subsoils. Then lower the tube together
with all magnets and necessary accessories fixed in position into a 100 mm diameter borehole
backfilled with a suitable bentonite-cement grout mix.
The magnetic rings to be housed in splay PVC holders ("spider magnets") suited to the ground.
Once in position the spider magnets shall be released. Where the access tube passes through
upper stiff crusts or fill material, sleeve with a larger diameter tube to pass freely through these
materials as settlement takes place.
Where extensometer is used in earth filling situation, the access tube and outer sleeve shall be
extended as filling progresses. The top of the access tube, and the larger diameter sleeve where
present, shall be protected with a suitable cover with facility for locking.
Unless otherwise shown in drawings, install the magnetic rings at depth with an interval not exceeding 3
m.
Grout the complete downhole assembly in place ensuring that the access tube and magnets remain
undisturbed during grouting operations.
Seal the access tube to prevent ingress of ground water.
4.5.1.2
Measurement
Immediately before or after taking a series of readings, the level of the top of the access tube shall be
measured by standard levelling techniques.
Measure relative movement between the magnetic ring and the reference magnetic ring (at either the
top or bottom) by a reed switch attached to a stainless-steel tape.
The position of each magnet shall be measured twice, once while moving upwards and once while
moving downwards towards the magnet by raising and lowering the steel tape and reed switch
assembly from the top of the borehole.
Refer to specific standards or manufacturer’s specifications or guides, wherever possible, on
tolerances, characteristics, accuracy of instrumentation and monitoring, to the acceptance of SO.
4.5.2
Rod Extensometers
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4.5.2.1
Rods and Rod Assembly
Isolate each rod individually by its own plastic sleeve and grout the complete assembly in place,
fixing the anchors to the ground but allowing free movement of each rod within its sleeve.
Ensure a single reference housing receives all of the rods from a drill hole and provide protection to
the reference head and measurement device.
Rods shall be stainless steel of a grade suitable to the site environment and duration of the
measurement and monitoring. Make provision for threading the anchor points onto the rod.
Install no more than 6 rods in a single hole with each rod of a different length so that displacements at
various borehole depths shall be recorded.
Where more than 6 rods are required, prepare another borehole as close as possible to the initial hole
and rods set at alternate depths in each hole.
4.5.2.2
S4.5.2.2
Not In Use
Use of Casing
Use casing to stabilise holes through unstable ground.
Determine the lengths of rods using the level of the ground at the hole location. For grout used for backfilling, use
bentonite/cement mix with just sufficient water to allow it to be tremied to the bottom of the holes.
4.5.2.3
Measuring Head
Measuring head shall allow manual readings to be taken as well as automated readings.
Cabling to the terminal box shall be capable of accepting up to 6 extensometers from each hole.
Provide a battery-operated digital readout device capable of reading to the required overall
accuracy.
Extensometers shall provide measurements of both elongations and reductions in the length between
anchorage point and measuring head possible.
Undertake remote reading using the electrical transducers linked to a logger station with a measuring
range of 150 mm. If movements potentially exceed 150 mm, make adjustment to allow continued
monitoring.
Use transducers that are waterproof to 15 bar.
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4.5.2.4
Measurement
Immediately before or after taking a series of readings, the level of the top of the access tube shall be
measured by standard levelling techniques.
Measure relative movement between the end anchor and the reference collar by an automated
measurement device (an electrical transducer) registering on the free end of the rod and by manual
means using a system to the acceptance of the SO.
Extend the reading range beyond that of the measurement device by a range adjustment device
fitted at the reference collar.
Refer to specific standards or manufacturer’s specifications or guides, wherever possible, on tolerances,
characteristics, accuracy of instrumentation and monitoring, to the SO for acceptance.
4.5.3
Tape Extensometers
Locate and fix anchors in a manner acceptable to the SO.
Use the same extensometer for each set of readings to maintain consistency.
Provide a minimum of 2 tape extensometers at the commencement of work and these are to be
calibrated against each other, so that in the event of damage to one tape, accuracy is not
compromised.
4.5.3.1
Measurement
Take measurements by connecting the tape hook to one eyebolt and then extend the tape across
to the next bolt. Adjust the tension of the tape and take the tape and calliper readings.
4.6
Deep Levelling Datum
4.6.1
Installation
Install a 300 mm diameter casing not less than 4 500 mm into firm/competent ground where SPT N
= 50 subject to the SOs approval. Install the 250 mm diameter casing of not less than 1 500 mm
beneath the 300 mm casing and fill with water cement grout that is just pumpable. Ensure the
founding depth of deep levelling datum shall be such that the founding strata is not affected or will not
be influenced by the construction activities or Works.
Fill the annulus between the 2 casings with grease. The top of the 25 mm steel rod shall be domed
and centre punched.
4.6.2
Protection
Propose for the SOs acceptance measures to protect the top of the Deep Levelling Datum by a
manhole cover and by a surface protection barrier.
4.7
Piezometers
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4.7.1
Piezometer installation
Install each piezometer in a separate borehole of 100 mm nominal diameter.
Carry out the complete installation as soon as practicable, and no later than 24 hours, after drilling in
order to minimise the amount of deterioration or alteration of the ground at the location of the
piezometer tip. Carry out drilling to the required depth without the use of air- flush in the vicinity of the
tip position.
4.7.2
Use of casing
Use casing to stabilise the hole through unstable ground.
If casing is used to maintain the hole open, withdraw it carefully so as not to damage the instruments or
cables, concurrently with the progress of the backfilling.
4.7.3
Installation of Sand Filter
In placing the sand, ensure that no sand adheres to the soil in the sides of an unlined hole. Where
there is water in a hole, allow sufficient time for all the sand to settle, and take measurements of the
upper surface of the sand from time to time to ensure this. Record the final elevation of the top of the
sand.
The filter element shall have a pore diameter of the order of 60 microns. Join the tubes together and
to the porous element with threaded couplings, tape and glue in such a manner that the joints remain
leakproof under the anticipated head of water. Use tube of at least 12 mm internal diameter to allow
air bubbles to rise freely.
Make arrangements to ensure that no sand adheres to the soil on the sides of the unlined
borehole. If there is water in the borehole, allow sufficient time for all sand to settle. Record the
final elevation of the top of the sand level. Place the porous element in the hole and add the
remaining sand filter as described above. Measure the final elevation of the top level of the sand
filter by a flat-ended sounding rod. Take sufficient number of soil samples from the drill-hole to
accurately determine the subsurface profile and agree with the SO on the appropriate tip levels
for the piezometers.
4.7.3.1
Bentonite Seal
Install seals consisting of bentonite pellets above, and if necessary, below a sand filter. The seal plug
shall not be less than 1.0 m thick. Fill the remainder of the hole with a bentonite- cement grout,
and the top part with concrete with caps and air vents as indicated on the drawing.
Tamp the bentonite seal formed of either stiff hard rolled balls or pellets over the sand to a thickness of
approximately 1.5 m. Backfill the hole with bentonite-cement grout mix to the acceptance of the SO.
Terminate grout backfill at the base of the instrumentation chamber.
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4.7.3.2
De-airing of Piezometer Tip
Check that the tip of each piezometer is air free and the porous stone of the tip is fully saturated by
submergence in clean de-aired water for a period of at least 24 hours prior to installation.
Confirm complete de-airing of the porous stone by periodic weighing.
4.7.3.3
Testing Before Installation
Test all piezometers before installation by submergence in still clean water to a series of depths
appropriate to the anticipated pressure range of operation in order to verify the calibration and
accuracy of the instrument.
4.7.3.4
Records
Keep accurate records of the depths of the piezometers, sand surrounds and seals, and record
readings at each stage of the installation. For push-in piezometers, record the increase in pore
pressure as well as dissipation using a data logger.
Check the maximum pressure allowable during installation to be 50% of the maximum for which the
piezometer is rated.
4.7.3.5
Commissioning Test
On completion of the installation, commission all standpipes and piezometers as appropriate, using a
falling head test by filling the standpipe or piezometer full with water to the top of the PVC tubing.
Carry out a simple falling head test and monitor the drop in water level in the piezometer at intervals
of 15 secs, 30 secs, 1 min, 2 mins, 4 mins, 8 mins, 15 mins, 30 mins, 1 hr, 2 hrs, 3 hrs, 4 hrs, 5 hrs,
6 hrs, 7 hrs, 8 hrs, 16 hrs, 24 hrs, or when the water level has returned to its initial steady level. Before
taking initial readings, stabilise the piezometer by alternately baling and filling at least 10 times.
Measure the depth to water using an electric type dip meter. The water standpipe or piezometer
shall be in working condition throughout the monitoring period. Rectify any damaged piezometer
before handing over.
Take samples of ground water of not less than one litre from the piezometer when required. Store
the water samples in clean sealed containers, clearly label and deliver to the laboratory for chemical
tests. The tests for sulphate content (% SO3), chloride content, acidity (pH value) and degree of
salinity shall be determined from the same sample.
4.8
Strain Gauges
Ensure strain gauges and cabling to be compatible for their intended location. Protect them against any
disturbance from the site activities.
4.8.1
Not In Use
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S4.8.1
Strain Gauges Embedded in Concrete
Use the embedment variety or securely attach to mounting plates welded to bars that are then
attached to the reinforcement.
The method of attachment shall prevent displacement of the gauge or damage to the wires and
cables during fixing of reinforcement, concreting, driving or other processes.
Attach the bars at 2 locations only to limit the bending induced in the bars to less than 50µε during
installation.
4.8.2
Strain Gauges for Temporary Struts
Use spot weldable strain gauges to the SOs acceptance. At the beginning of strut monitoring, install
strain gauges in strut together with load cells for calibration purposes. Establish a correlation between
the gauges and loads measured by the load cells and submit the results for review by the SO.
Gauges from the same type and source shall then be used to monitor other selected struts in place
of load cells. The locations of struts required strain gauges are shown in the drawings.
4.9
Tell-Tales
Fix the overlapping plates securely so that a gap of not greater than 1 mm separates them at the start
of monitoring and so that the cross-hairs are zeroed. Record the location, orientation and plate
separation for each Tell-tale on the reading sheets.
4.10
Markers, Crackmeters and Tiltmeters
Typical details of acceptable installations for ground and building settlement points are shown in the
drawings.
Submit for approval details of any alternative installations proposed.
4.10.1
Accuracy of Levels
Monitor and record the levels of ground survey and building settlement points throughout the duration
of the Works, using a precise level and staff accurate to 0.5 mm or better.
4.11
Inspection of Adjacent Property
Keep adjacent roads, neighbouring properties and structures clear of equipment and spoils and
regularly inspect the surface of the ground, properties and structures.
Report to the SO immediately any signs of subsidence, movement or cracks.
4.12
Completion
Remove all specialist monitoring and make good all installations to the satisfaction of the SO upon
completion of the monitoring, or at other such times if accepted by the SO.
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5
VERIFICATION AND SUBMISSIONS
5.1
Submissions
5.1.1
Description of Instrumentation
Provide fully detailed drawings, together with descriptions of the principal features, mode of operation,
the measuring range and the degrees of accuracy of the equipment.
5.1.2
Method Statement
Submit detailed method statements for the installation of all instruments for the acceptance of the SO
prior to installation.
5.1.2.1
Content
Method statements shall include, at least the following information:
(a)
Details and drawings of instruments
(b)
Manufacturers specifications and recommendations for installation and maintenance, etc., details of drilling
equipment and drilling methods
(c)
Details of all materials (including samples)
(d)
Details of sequence of assembly and connections
(e)
Details of any backfill, proposed grout mixes
(f)
Details of monitoring arrangements and verification procedures
The method statement shall also include a programme of installation related to the main construction
activities to the acceptance of the SO.
5.1.3
Installation Drawings
Submit detailed drawings showing the precise location and depth for instrument installation for the
acceptance of the SO prior to commencement of installations.
5.1.4
Schedule of Manpower and Resources
Provide a detailed schedule of manpower and equipment resources to be employed for the Works for
SOs acceptance before commencement within timeframe as directed.
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5.1.5
Data Management System
Submit full details of the proposed data management system for the acceptance of the SO. These shall
include proposed formats for data acquisition, checking, processing, and subsequent reporting to the
SO for all instruments.
5.1.6
Anomalous Readings
Whenever sets of data are measured, review the measurements with to earlier sets of data for any
anomalous readings or gross errors in measurements which differ from the expected value or trend.
Immediately proceed to take additional readings to verify data. If the anomalous measurement
values persist, notify the SO and carry out investigation to find the reasons for the anomalous
readings.
5.1.7
Calculations
Provide calculations to convert raw output to processed data for all instrumentation.
Provide a sample calculation with appropriate data listings to the SO, endorsed by a qualified,
competent and experienced PE who is directly responsible for the instrumentation and monitoring.
5.1.8
Maintenance and Inspection Schedule
Submit a maintenance and inspection schedule prior to installation or use of the instrumentation for
the acceptance of the SO.
5.1.9
Quality Control Manual
Submit a Quality Manual containing a Quality Assurance / Quality Control (QA/QC) programme
for the Works to the SO for acceptance within directed time frame.
The Quality Manual shall include at least information on the following:
(a)
Quality policy
(b)
Organisation charts and responsibilities
(c)
Internal quality control and audits
(d)
Facilities and equipment
(e)
Calibration and testing of equipment
(f)
Testing and inspection procedures
(g)
Sub-contractors and suppliers
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5.2
Calibration of Instrumentation
Correctly calibrate all the installed instrumentation in use.
Carry out calibration and provide certificates by an accepted accredited agency.
Carry out periodic checks at appropriate intervals to confirm the validity of calibration of equipment in
accordance with the manufacturers instructions and make any necessary adjustments. Check
instruments to have a validity of calibration at least 3 months after their last intended reading in the
project.
Repeat calibration if anomalous readings are recorded.
Keep records of checks, errors recorded and whether any adjustment was undertaken.
5.2.1
Records of Calibration
Keep records of all calibration certificates and of dispatch of equipment off site for rewhen required.
Retain copies of all certification and other records on site and make available for the SOs inspection
when required.
After installation, the functioning of each instrument shall be demonstrated to the SO, including the
recording of measured values using the appropriate readout device. As part of the commissioning, 3
sets of readings shall be taken and compared. When instruments are installed before earthwork
starts, then these 3 sets of readings shall also be taken before construction starts. If there are
significant differences or anomalies, then further readings shall be taken. Once 3 sets of
comparable readings have been taken, these shall be averaged to form the base readings,
representing conditions before construction starts.
In cases where instruments are installed during construction, 3 sets of readings shall be taken in quick
succession and the results compared. Use these results to provide base readings in a manner to be
agreed with the SO.
5.3
Records and Reporting
5.3.1
General
Submit 2 copies of preliminary records of the installation of each instrument within 24 hours from the
time of installation of each instrument.
Submit final records for each instrument incorporating any comments from the SO within 7 days of
completion of installation of each instrument.
5.3.2
Record Information
Submit installation record sheet for each instrument installed.
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5.3.2.1
Instrumentation Installation Record Sheet
The format of the instrumentation installation record sheet together with execution details shall be
submitted to the SO for approval at least one week before installation commences.
The record sheet shall include the following information in addition to the general information required:
5.3.2.2
(a)
Existing ground level at the time of installation.
(b)
A log of ground conditions or geotechnical information.
(c)
Planned and as-installed instrument location in plan and elevation.
(d)
Planned and as-installed instrument orientation.
(e)
Type of backfill materials used, and dimensions such as length, width, diameter, depth and volumes of
backfill.
(f)
Plant and equipment used, including diameter and depth of any drill casing used.
(g)
Verification measurements or readings during installation to ensure that all installation steps have been
followed correctly, including acceptance tests.
(h)
Weather conditions.
(i)
Problems encountered, delays, unusual features of the installation, and any events that can influence the
instrument readings or measurements.
(j)
A record of commissioning information, tests and readings.
(k)
Legend and any colour coding used.
Instrumentation Installation Report
Submit to the SO the specified number of copies of each installation report within one working day
of completion on the installation, including taking of initial readings supplementing the planned details
with the as-built details. The records shall incorporate a
graphical illustration of the instrument installation and shall include the following information to
supplement the installation record sheet:
(a)
Instrument number and location (co-ordinates in accordance with the project grid reference and level).
(b)
Names of personnel responsible for installation.
(c)
Time and date for commencement and completion of installation.
(d)
Details and records of boreholes.
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5.3.3
(e)
Plant and labour used.
(f)
Ground conditions encountered (if applicable).
(g)
Details of instrument installation (grout, fixings, etc).
(h)
Instrument readings during installation, and immediately after calibration and installation is complete.
(i)
Location of instrument terminals, housings and any leads or cabling.
(j)
Details of any splices, numbers of casings or joints.
(k)
Details of any breakdowns or delays.
Datum Readings of Survey Points
The Registered Surveyor shall establish the initial (datum) reading of each survey point and submit
records with Registered Surveyors endorsement to the SO. Unless otherwise agreed, submission of
the datum readings should occur prior to any excavation and construction works.
5.3.3.1
Survey Datum to be established for Monitoring Works
The Registered Surveyor shall establish the horizontal and vertical survey datum from Singapore
Land Authority (SLA) Integrated Survey Network (ISN) markers in SVY21 datum; and vertical datum
from Vertical Control Points (VCPs).
Refer to Land Surveyors Board (LSB) Directives on Engineering & Hydrographic Survey Practices.
5.3.3.2
Periodic Maintenance Survey of Monitoring survey datum
The survey datum shall be surveyed at quarterly intervals as a verification of the stability of the base
datum and that their accuracy is up-to-date with correct datum reference for the periodic
monitoring survey works.
Refer to Land Surveyors Board (LSB) Directives on Engineering & Hydrographic Survey Practices.
5.3.4
Submission of Readings
Submit all instruments readings in approved tabular and graphical formats (electronic and paper
based), within 24 hours of monitoring.
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5.3.5
Presentation of Reading in Graphic Format
Submit to the SO for acceptance on the graphic presentation of the measurement data. prior to the
commencement of instrumentation field work. Hand plotted graphs are not acceptable.
Provide the same time-axis scale for all time-plots.
Submit for SOs acceptance on the format of plots involving presentation of parameters together such
as fill thickness, settlement and excess water head measurements at about the same location.
Submit for SOs acceptance on the presentation layout, scale and details for the instrumentation at the
time of submitting the format of plots.
5.3.6
Factual Reporting
Submit reports of monitoring results in a factual report at intervals as agreed by the SO, in an
acceptable format, including a plan showing the location of the structure and instrumented lines and
shall comprise at least the following:
(a)
Incorporate plots of measured parameters vs time, depth and/or location of construction activity with
reference to each instrument, etc. as agreed with the SO.
(b)
Include a comparison of data with predetermined trigger values. (e.g. settlement vs time, horizontal
deflections vs time, load vs depth of excavation, settlement vs location of construction activity / depth of
excavation, etc.).
(c)
Highlight idle or damaged instrument and provide estimated time frame for corrective measures.
Submit reports of monitoring results in a factual report at intervals to be agreed with the SO. Propose to
the SO for his acceptance on the frequency of reporting as appropriate.
5.3.7
Interpretative Reporting
5.3.7.1
Frequency
Where required or directed by the SO, propose for the SOs acceptance on the frequency of
submitting the interpretative reports as appropriate based on the factual information received for the
Works.
When established trends indicate potential problems then such areas of concern shall be reappraised and monitored at revised frequency as directed by the SO.
5.3.7.2
Report Content
Interpretative Reports shall include a summary plot of all instrumented lines or points which indicate a
trend (including historical data where appropriate) that could result in a trigger level being exceeded
and any instrumented line or point in which a trigger level has been exceeded.
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(11) C03-010 Concrete Construction Generally
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1
S1
Not In Use
GENERAL
Read this Section with G01-010 "General Requirements" and all other contract documents. Read in
conjunction with BS EN 13670 Execution of Concrete Structures.
1.1
Not In Use
S1.1
Scope
This work section covers general requirements for the use of structural quality concrete in plain, reinforced or
prestressed structures. Relevant requirements may also be adopted for non-structural concrete, for example in
external works. For particular requirements of specialists works such as prestressing and pre- cast, refer to the
respective sections.
1.2
Related Sections
Read this Section in conjunction with the relevant requirements of the following sections:
C03-020
Reinforcement
C03-030
Formwork and Falsework
C03-040
Designed Joints
1.3
Standards, Codes, Regulations and Technical References
1.3.1
Not In Use
S1.3.1
Standards and Codes
Unless otherwise agreed by the SO, ensure all of the Works comply with the relevant requirements
of the standards and codes listed below or referenced in the body of the Specification. Alternative
standards and codes may be proposed for approval by the SO, provided it can be demonstrated that
the alternative standards and codes comply with the requirements of the standards specified. All
standards and codes quoted are the current version, unless specific year references are noted.
In the event that the standards or codes are partially superseded or have become obsolete, refer to
the current edition or the approved substitution for the relevant clauses.
Singapore Standards
SS EN 197-1
Cement – Part 1: Composition, Specification and Conformity Criteria for
Common Cements
SS EN 197-2
Cement – Part 2: Conformity evaluation
SS EN 197-4
Cement - Part 4: Composition, specifications and conformity criteria for low early
strength blast furnace cements
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SS EN 206
Concrete – Specification, performance, production and conformity
SS EN 1990
Eurocode – Basis of structural design
NA to SS EN 1990
Singapore National Annex to Eurocode – Basis of structural design
SS EN 1992-1-1
Eurocode 2: Design of concrete structure – Part 1-1 General rules and rules for
buildings
NA to SS EN 1992-1-1
Singapore National Annex to Eurocode 2: Design of concrete structure – Part
1-1 General rules and rules for buildings
SS EN 1992-1-2
Eurocode 2: Design of concrete structure – Part 1-2 General rules –
Structural fire design
NA to SS EN 1992-1-2
Singapore National Annex to Eurocode 2: Design of concrete structure – Part
1-2 General rules – Structural fire design
SS EN 1992-2
Eurocode 2: Design of concrete structures – Part 2: Concrete bridges Design and detailing rules
SS EN 1992-3
Eurocode 2: Design of concrete structures – Part 3 Liquid retaining and
containment structures
SS EN 12620
Specification for aggregates for concrete
SS EN 13791
Assessment of in-situ compressive strength in structures and precast
concrete components
SS EN 15167
Ground granulated blast furnace slag for use in concrete, mortar and grout Part
1:Definitions, specifications and conformity criteria
Part 2:Conformity evaluation
SS EN 934-1
Admixtures for concrete, mortar and grout – Part 1: Common requirements
SS EN 934-2
Admixtures for concrete, mortar and grout – Part 2: Definitions,
requirements, conformity, marking and labelling
SS EN 934-4
Admixtures for concrete, mortar and grout – Part 4: Admixtures for grout for
prestressing tendons
SS EN 934-6
Admixtures for concrete, mortar and grout – Part 6: Sampling, conformity control
and evaluation of conformity
SS 544-1
Concrete – Complementary Singapore Standard to SS EN 206 – Part 1:
Method of specifying and guidance for the specifier
SS 544-2
Concrete – Complementary Singapore Standard to SS EN 206 – Part 2:
Specification for constituent materials and concrete
SS 592
Assessment of in-situ compressive strength in structures and precast concrete
components – Complementary guidance to that given in SS EN 13791
SS 78
Testing concrete
Part B1– Guide to the use of non-destructive methods of test for hardened
concrete.
Part B7– Recommendations for assessment of concrete strength by the
near-to-surface tests
Other Standards
BS EN 932
Tests for general properties of aggregates.
BS EN 933-1
Tests for geometrical properties of aggregates. Determination of particle size
distribution. Sieving method
BS EN 1008
Mixing water for concrete, specification for sampling, testing and assessing the
suitability of water, including water recovered from processes in the concrete
industry, as mixing water for concrete
BS EN 13670
Execution of concrete structures
BS EN 12350-1
Testing fresh concrete
Part 1: Sampling and common apparatus
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1.3.2
BS EN 12350-2
Testing fresh concrete – Part 2: Slump-test
BS EN 12504
Testing concrete in structures - Part 1 Cored Specimen – taking, examining and
testing in compression.
BS EN 12390-1
Testing hardened concrete – Part 1: Shape, dimensions and other
requirements for specimen and moulds
BS EN 12390-2
Testing hardened concrete – Part 2: Making and curing specimens for
strength tests
BS EN 12390-3
Testing hardened concrete – Part 3: Compressive strength of test
specimens
BS EN 12390-7
Testing hardened concrete – Part 7: Density of hardened concrete
BS EN 12390-8
Testing hardened concrete – Part 8: Depth of penetration of water under
pressure
BS 5606
Guide to Accuracy in Building
BS 8204 Part 1
Code of practice Screeds, bases and in situ floorings. Concrete bases and
cementitious levelling screeds to receive floorings.
PD 6682-1
Aggregates. Aggregates for concrete. Guidance on the use of BS EN
12620
Regulations
(a)
1.3.3
Building Control Act and Regulations
Technical References
Refer to the following technical references for guidance in carrying out the Works:
(b)
SAC CT 05 - SAC Criteria for Certification Bodies (Ready-Mixed Concrete)
(c)
SAC CT 06 - SAC Criteria for Ready-Mixed Concrete Producers
(d)
BCA, Guidebook on Sustainable Construction : A Guide on Concrete Usage Index
(e)
BCA, Guidebook on Sustainable Construction : The Use of Recycled Materials
(f)
British Cement Association Guide. Kickerless Construction, Ref. 47.023, 1988.
(g)
Building Research Establishment. Concrete in aggressive ground. Special Digest 1. 3rd edition. Watford:
Building Research Establishment, 2005.
(h)
CIRIA Report C766 Early age thermal crack control in concrete (2019)
(i)
PD 6682-1:2009 Aggregates. Aggregates for concrete. Guidance on the use of BS EN 12620
(j)
ERMCO, The European Guidelines for self-compacting concrete - specification, production and use.
Brussels, European Ready-Mixed Concrete Organisation, 2005.
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1.4
S1.4
1.4.1
(k)
Harrison, T. A. and Brooker, O. How to use BS 8500 with BS 8110. Camberley, The Concrete Centre,
2005 MONKS, W. Plain formed concrete finishes. Technical Report
52. First edition. Camberley: The Concrete Society, 1999.
(l)
Concrete Society Materials Group, Development in durability design and performance-based
specification of concrete. CS 109. Camberley: The Concrete Society, 1996.
(m)
THE Concrete Society, Guidance on the use of stainless steel reinforcement. Technical Report 51. First
edition. Camberley: The Concrete Society, 1998.
(n)
Quillin, K., Nixon, P.J., Mattiiews, J. D., and Longworth, T. I. Concretes with high ggbs contents for use in
hard/firm secant piling. Information paper IP 17/05. Watford: Building Research Establishment, 2005.
(o)
Bamforth, P. B. Enhancing reinforced concrete durability. Technical Report 61. First edition. Camberley:
The Concrete Society, 2004.
(p)
Concrete Society. Concrete industrial ground floors - a guide to design and construction. Technical
Report 34. Third edition. Camberley: The Concrete Society, 2003.
(q)
Building Research Establishment. Shrinkage of natural aggregates in concrete. Digest
357. Watford: Building Research Establishment, 1991.
(r)
Dhir, R. K., Limbachiya, M. C. and Beggs, A. Resolving application issues with the use of recycled
concrete aggregate. University of Dundee, DETR Research Contract 39/3/478 (CC 1697), March 2001.
(s)
Building Research Establishment. Alkali-silica reaction in concrete. BRE Digest 330 (in four parts).
Watford: Building Research Establishment, 2004.
(t)
Quillin, K. Delayed ettringite formation - In-situ concrete . Information Paper IP11/01. Watford: Building
Research Establishment, 2001.
Su)
CONQUAS 21 (BCA)
Not In Use
Trade Preambles
Not In Use
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S1.4.1
Concrete Product
Concrete for building and civil engineering structures is required to be supplied by Ready- Mixed
Concrete (RMC) plants which are certified under the Singapore Accreditation Council (SAC)
Certification Scheme for RMC based on SS EN 206, SS 544 and SAC CT 05 and SAC CT 06.
This shall include on-site batching plants as well as plants supplying concrete for structural
elements. Comply with the Building Control Regulations on ready-mixed concrete and product
conformity certificate. Engage qualified and experienced personnel to prepare and submit concrete
mix design to SO's acceptance.
1.4.2
Product Control System
The concrete producer is required to have a documented production control system stated clearly in a
production control manual based on SS EN 206, SS 544 and SAC CT 05 and CT
06. Comply with the Building Control Regulations on ready-mixed concrete and product conformity
certificate.
1.4.3
Construction Joints
Engage qualified and experienced personnel to prepare and submit proposal on suitable construction
joints and details for acceptance by the SO.
S1.4.4.
Noise Nuisance
Take all necessary actions to ensure compliance with the Environment Public Health Act, under
Section 46 or the latest noise control regulations imposed by the NEA or any relevant authorities.
The noise level at the nearest occupied building outside the Site is not to exceed the following
maximum permissible noise level, or shall have met the noise control guidelines introduced by NEA
whichever is the more stringent:
Type of occupied buildings
Applicable period
Maximum allowable equivalent
continuous noise level measured
over a period of 5 minutes in dB
(a) Hospital, school, home for
7am to 7pm
75
7pm to 7am
55
7am to 7pm
90
7pm to 10pm
70
10pm to 7am
55
7am to 7pm
90
7pm to 7am
70
the aged, sick etc.
(b) Residential buildings
located less than 150m from
the construction site
(b) Buildings other than those in
(a) above
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PERFORMANCE REQUIREMENTS
2.1
Certified Concrete Product
Ensure that concrete for building and civil engineering structures shall be obtained from RMC plants
which have been certified under the SAC’s Certification Scheme for RMC as provided in SS EN 206
and in Building Control Regulations.
2.2
Control on Shrinkage and Temperature Effects
Control the construction such that any crack due to shrinkage and temperature effects does not
exceed 0.1 mm wide.
2.3
Control on cracks
Control and minimise cracking from all causes. Unless otherwise indicated in drawings, or agreed or
directed by the SO, limits on cracking shall follow the SS EN 1992.
2.4
Construction Loads
Ensure during construction that the structure is not subjected to loads that will cause short- term or
long-term distress to the concrete.
2.5
Execution Class
The Execution Class shall be based on SS EN 1990 and as defined in BS 13670.
Unless otherwise indicated in the drawings or directed by the SO, other than for construction such as
high strength concrete, post-tensioned construction, bridges and critical structures etc, minimum
class for general construction shall be Execution Class 2.
S2.6
Modifications
Obtain written agreement of the SO to any modification of this Specification before any work is
started.
S2.7
Acceptance Procedure
The SO shall comment on all information supplied within five working days of receipt. Acceptance or
agreement by the SO shall have no effect unless given in writing.
3
S3
Not In Use
MATERIALS
Concrete shall conform to SS 544-2 and SS EN 206-1.
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3.1
Cement
3.1.1
Portland Cement
Comply with SS EN 197.
3.1.2
Sulfate-resisting Portland Cement
Comply with the requirements of SS EN 197-1, Clause 7.4.2
3.1.3
Pulverized Fly Ash (Pfa)
Comply with the requirements of SS EN 197-1, Clause 5.2.4 (Fly ashes).
3.1.4
Ground Granulated Blastfurnace Slag (GGBS)
Comply with the requirements of EN 197-1, Clause 5.2.2 (Granulated blastfurnace slag).
3.1.5
High Alumina Cement
Do not use.
3.1.6
Silica fume
Comply with the requirements of EN 197-1, Clause 5.2.7 (Silica fume).
3.2
Fine Aggregates
Comply with SS EN 12620 and fine aggregates shall not be alkali reactive.
3.2.1
Not In Use
S3.2.1
Testing
Be in accordance with BS EN 932 Tests for general properties of aggregates, and BS EN 9331 Tests for geometrical properties of aggregates and in accordance with SS EN 12620
3.2.2
Not In Use
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S3.2.2
Grading
The grading of the fine aggregates, determined in accordance with EN 933-1, shall comply with the
requirements of SS EN 12620 as appropriate to the aggregate size.
Grading shall be based on sieve analysis as described in SS EN 12620 and to be within the limits of
the grading zones described as per the mix requirements and in the standards subject to a
tolerance of 5%.
The producer shall document and, on request, declare the typical grading for each fine aggregate size
produced.
In addition, unless otherwise agreed by the SO, fine aggregates shall comply with the requirements
specified in SS EN 12620 Table 4.
3.2.3
Alternative to sand
Propose for the SOs acceptance on the use of quarry dust for substitution for sand as fine aggregates
in specified applications.
3.3
Coarse Aggregates
Comply with SS EN 12620.
All coarse aggregates shall comply with the general grading requirements specified in SS EN 12620
Table 2, appropriate to their size designation.
3.4
Water
All water used for mixing concrete, mortar and grout, for cleaning out formwork and for curing shall be
clean and free from harmful matter in solution or suspension.
If taken from a source other than the Public Utilities Board, test in accordance with BS EN 1008.
3.5
S3.5
Not In Use
Admixtures
Comply with the requirements of SS EN 934-2 and SS EN 206-1. Submit for the SO’s
acceptance of admixtures with detailed information, including name, type, dosage and
justification for the use.
3.5.1
Not In Use
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S3.5.1
Air Entrainment
Air entraining admixtures shall comply with SS EN 934-1 and SS EN 934-2. Where other types
of admixture are to be used together with air entrainers, comply with the requirements of SS EN
206 and SS 544 that the performance is not compromised.
3.5.2
S3.5.2
Not In Use
Chloride Content
Calcium chloride and chloride-based admixtures shall not be used, and shall not be added to concrete
containing steel reinforcement, prestressing steel reinforcement or other embedded metal. Comply
with SS EN 206 on the limits of chloride content.
Provide written evidence of conformance.
3.5.3
Waterproofing Admixture
Refer to Section C03-050 "Water Resistance to Concrete Structures" for general requirements
of waterproofing admixture.
3.6
Method of Specifying Concrete
3.6.1
Not In Use
S3.6.1
Designated Concrete
Submit for the SO’s acceptance designated concrete as defined in SS 544 to be produced that shall
satisfy requirements for strength and durability, and for designated applications.
Submit for the SO’s acceptance the product conformity certification and the third-party certification in
accordance to SS EN 206 and SS 544.
[Note 1: Use of designated concretes is intended to encourage standardisation.]
Designated Concrete
The parts below shall be supplied as prescribed mixes in accordance with SS 544-1 and SS EN 2061
1
Requirements
Defaults
Defaults
Defaults
Concrete designation
RC32/40
RC35/45
RC40/50
20
20
20
(ref SS544-2 Table 5)
2
Maximum aggregate size (mm)
Enter 10, 14, 20 or 40
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3
Consistence class
S3
S3
S3
None
None
None
Special requirements for aggregates (enter
None. Comply
None. Comply
None. Comply
reference if required)
with SS EN
with SS EN
with SS EN
12620
12620
12620
S1, S2, S3, S4
4
Special restrictions on cement types (enter
reference if required)
5
6
Use of RCA permitted?
Maximum mass fraction of total coarse
Yes for
Yes for
Yes for
superstructure.
superstructure.
superstructure.
20%
20%
20%
aggregate enter a higher mass fraction of total
coarse aggregate where permitted (Ref SS
544-1 cl 4.2.3c)
7
Requirements for accelerated or retarded set
None
No
No
8
Special colour requirements
None
None
None
None or see 4.11.4
9
10
Type and dosage of fibres
Refer to C3-20 Refer to C3-20 Refer to C3-20
Chloride class Cl1.0 for GEN series, Cl0.20 for
Cl 0.40
Cl 0.40
Cl 0.40
SRPC, Cl 0.40 for all other concretes or enter
special requirements
11
Minimum air content
None
None
None
12
Method of placing content
Normal
Normal
Normal
13
Requirement for finishing concrete
None
None
None
14
Identity testing for consistence or other
No
No
No
properties required in accordance with SS EN
206-1 Annex B and SS544-1 Annex B. (If yes
then details to be added into section 6
Notes
1. All sections of the specification must be completed before it is passed to the producer. The person
sending the final specification to the producer must send copies of the document to all other parties
(SO, Engineer, Employer as appropriate) who have contributed to the specification.
2. Where ‘None’ is entered in the table this is a default value to ensure that the specification is
complete. All those involved in completing the specification need to check if ‘None’ is applicable
3. Guidance on specification of designed concrete can be found in SS544-1, section 4.2.
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3.6.2
Designed Concrete
Submit for the SOs acceptance designed concrete as an alternative to designated concrete as
defined in SS 544 to be used where the requirements are outside of those covered by designated
concretes.
[Note 1: The environment to which the concrete is to be exposed is identified in SS 544 Part1.
Using the intended working life and the minimum cover to reinforcement, the limiting values of
composition are determined for each of the identified exposure classes using the guidance
in A.4 of SS 544 Part 1. The requirements for the concrete are selected from the composite of limiting
values plus structural and fire considerations, and the specification requirements will follow in
accordance with 4.3 of SS 544 Part 1.
Note 2: Guidance on the specification of designed concrete to resist identified exposure classes is
given in A.4 of SS 544 Part 1.]
3.6.3
S3.6.3
Not In Use
Prescribed Concrete
Submit for SO’s acceptance where prescribed concrete is to be used in accordance with SS EN 206
and SS 544, and with evidence that the initial testing to determine that the specified proportions
shall achieve the intended performance in the fresh and hardened states with an adequate margin
as required in SS EN 206. Where prescribed concrete is used, ensure that the specified
proportions do not result in damaging alkali-silica reaction (ASR). Where required, provide
concrete mixes in the PSD
3.6.4
S3.6.4
Not In Use
Chloride Content
Limit the chloride content of the proposed concrete, including chloride contained in the admixtures, to
that specified in SS EN 206-1, Clause 5.2.8 (Chloride content), ad SS 544-2 Clause 5.3 (Chloride
content).
Provide written evidence of conformity.
3.6.5
Sulfate Content
Limit the sulfate content in the proposed concrete in accordance with SS 544-2, Clause 4.3
(Aggregates).
3.6.6
Calcium Chloride
Calcium chloride shall not be included in any concrete.
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3.6.7
Alkali-Silica Reaction
Ensure that the requirements with preventative measures in accordance with SS EN 206, Clause
5.2.3.5 (Resistance to alkali-silica reaction) and SS 544-2 Annex D (Minimizing the risk of
damaging alkali-silica reaction in concrete) and SS 544-1 Clause A.8.1 (Alkali- aggregate reaction)
are met to avoid any alkali-silica reaction. Test aggregates to determine any varieties of susceptible
silicas and for other requirements by the authorities or by the SO.
3.6.8
Additions or Changes
Do not make additions or changes to the fresh concrete after batching without the prior agreement of
the SO.
In the event of any addition to the fresh concrete before discharging on site, the concrete shall be
deemed non-conforming until identity testing for strength shows that the concrete is acceptable unless
the addition is made by the producer using a procedure agreed in advance with the SO.
3.7
Not In Use
S3.7
Ready-Mix Concrete Plant
S3.7.1
Third Party Accreditation
All concrete shall be ready-mix concrete. Ready-mixed concrete shall be supplied by a producer
from a plant holding current accredited third-party certification meeting requirements of SS EN 206-1,
Annex C and SS 544. Provide the SO with confirmation of the producer’s certification in
accordance with SS EN 206-1 Annex C3 and SS 544.
S3.7.2
Information Required
Details of a ready-mix concrete plant proposed for use shall be forwarded to the SO for
acceptance. Provide contingency plans prior to commencement of work in the event of supplies
being interrupted during a pour due to a plant breakdown. Where feasible, details of a suitable backup plant/supplier should be submitted to the SO for acceptance.
S3.7.3
Addition of water to ready-mixed concrete
Water should not be added on site but if it is added to the concrete truck mixer drum before
discharge on site, the concrete shall be deemed non-conforming until identity testing for strength
shows that the concrete is acceptable unless the addition is made by the producer using a procedure
agreed in advance with the SO. The water added shall be recorded on the delivery ticket.
Note: The addition of water on site is undesirable and should be avoided wherever possible. It is
considered prudent to sample such concrete including the production and testing of concrete cubes
to verify that the required concrete strength has been achieved.
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3.8
Surface Hardener
The surface hardener shall consist of aggregate particles which have a hardness of not less than 7, as
measured on Moh’s hardness scale.
3.9
Sustainable Construction
3.9.1
General
Refer to the guidelines in BCA Publication on Sustainable Construction on ways to use less natural
aggregates which include:
3.9.2
S3.9.2
(a)
Recycling, upcycling and use of recycled materials
(b)
Efficient use of natural materials through lower concrete usage
Not In Use
Alternative substitutes
Submit for SO’s acceptance on the use of alternative substitutes, including recycled materials to
natural aggregates in accordance to SS EN 12620 and SS 544, particularly on the requirements
for both the use and testing of recycled concrete aggregates and recycled aggregates.
Do not use recycled aggregate and recycled concrete aggregate without approval. If allowed, recycled
aggregate and recycled concrete aggregate shall confirm to SS 544-2 Clause 4.3 (Aggregates),
section 3.3 (Fine aggregates), section 3.4 (Coarse aggregate), and other relevant local standards
and guidelines.
Refer also to the guidelines in BCA Publication on Sustainable Construction: A Guide on the Use of
Recycled Materials.
[Note 1: Any recycled materials shall comply with material tests as set out in this Section.
Recognised non-construction post-consumer or post-industrial by-products to be used for recycled
content include:
- ground granulated blast furnace slag (ggbfs)
- air-cooled blast furnace slag (acbfs)
- pulverised fuel ash (PFA)
- furnace bottom ash (FBA)
- silica fume
With cement replacement, due consideration shall also be given to concrete curing time and method as
appropriate.]
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3.9.3
Recycled concrete aggregates from demolition waste
Submit for SOs acceptance on the use of recycled concrete aggregates that are mainly derived
from the crushed concrete from demolition waste, for non-structural works involving constructing nonload-bearing walls, small drains, kerbs, footpaths, non-suspended slabs, lean concrete, etc. and for
road works as the sub-base in according to the requirements of Sections C070-010 and C07-020.
3.9.4
Concrete Usage Index
For demonstrating on the optimal use of concrete, the Concrete Usage Index (CUI) which is an
indicator of the amount of concrete used per unit floor area in building works as defined in the BCA
Guidebook on Sustainable Construction: A Guide on Concrete Usage Index, shall be used.
3.10
S3.10
Not In Use
Information on Concrete by Producer
Submit to the SO for approval, details of the proposed concretes in accordance with SS EN 206-1,
Clause 7.2 (Information for the producer of the concrete to the user) and SS 544-1 clause 5.2
(Information from the producer of the concrete to the specified or user), as appropriate.
S3.11
Storage of Materials
All materials shall be stored in an agreed manner that prevents damage or degradation and is in
accordance with all manufacturers requirements
4
WORKMANSHIP
4.1
Not In Use
4.2
Not In Use
S4.1
Transportation of Concrete
Supply and transport all concrete to the point of discharge from the mixer/agitator in accordance with
SS EN 206-1 Clause 7 (Delivery of fresh concrete) and SS 544-2 Clause 14 (Transport of concrete).
4.2.1
Not In Use
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S4.1.1
Delivery Tickets
Information shall be in accordance with SS EN 206-1, Clause 7.3 (Delivery ticket for ready- mixed
concrete) and SS 544-2, Clause 11 (Delivery of fresh concrete) and shall be completed and available
prior to discharge of concrete into the structure.
4.2.2
Not In Use
4.3
Not In Use
S4.2
Inserts
Ensure that any cast-in inserts are securely fixed prior to placing concrete.
4.4
S4.3
Not In Use
Placing and Compaction
Place and compact the concrete in accordance with BS EN 13670 Clause 8.4 (Placing and
Compacting).
Place and fully compact the concrete to avoid cold joints and honeycombing, and to minimise
segregation, excessive blemishes or other defects in the hardened concrete.
Compaction shall be carried out without causing damage of displacement to the formwork,
reinforcement, tendons, ducts, anchorages, inserts etc.
4.5
Not In Use
S4.4
Kickers
Kickers shall be monolithic with the slab, of sound construction and not less than 100 mm high.
Where kickerless construction is specified on the drawings provide details of the proposed method of
securing and sealing the column and wall shutters at floor joints to the SO for agreement, taking
guidance from the British Cement Association Guide: Kickerless Construction. Ensure robustness
of the chosen method of construction and cast a sample wall and column panel for the SO’s
approval.
S4.5
Premature Cessation
Suitable arrangements for premature cessation of a pour shall be agreed and in place before work
starts. Should premature cessation of a pour arise, agree with SO the extent and timing of any
necessary remedial work before resumption of placing.
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4.6
Construction Joints
4.6.1
Not In Use
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S4.6.1
General
Engage qualified and experienced personnel to prepare and submit suitable construction joints
and details for acceptance by the SO.
Position and form joints such as to suit the structure and to avoid distress to the structure. Unless
otherwise agreed with the SO, limit pour sizes as listed in the Table 1:
Table 1. Pour sizes
Construction
Max. Area (m²)
Max. Dimension (m)
Water-resisting walls
25
5
Water-resisting slabs
100
10
Slabs with major restraint at both ends
100
13
Slabs with major restraint at one end only
250
20
Slabs with little restraint in any direction
500
30
Walls
40
10
Note: Details and locations of construction joints should be agreed well in advance of any
construction. The Contractor shall position and form construction joints to suit the structure and so as
to not cause any long or short term distress to the structure particularly from thermal and shrinkage
effects.
Pour sizes should be agreed early in the construction period between the Contractor and the SO. The
Table has been included to provide a benchmark – the values given will be appropriate where the
experience and the resources of the Contractor are more limited, but may be amended subject to
the SO’s satisfaction with the values proposed.
It should be noted that the pour size is unrelated to the number of restraints imposed upon slabs.
The size and location of restraints define where special measures have to be taken regardless of
pour sizes.
Where the maximum size of pour permitted differs significantly from the values suggested by the
Table, the actual size should be specified in the Project Specifications. The Contractor may also
propose his own variation.
Controlled large area pours are frequently carried out where the economic conditions are suitable and
suitable construction methods are available. Ideally pours should only be restricted to the area that
the contractor can place in a working day.
Further guidance can be obtained by reference to Large Area Pours for Suspended Slabs
Reinforcing LINKS Issue 3 by RCC 1992 and published by British Cement Association.
The advice on pour sequencing, joint details etc. is different for ground supported slabs particularly
industrial and warehouse slabs. Guidance for this is given in a number of documents such as
Concrete Society Technical Report No 34, British Cement Association ‘Concrete ground floors: their
design, construction and finish’ etc.
4.6.2
Not In Use
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S4.6.2
Preparation of Construction Joints
Carefully prepare construction joint surfaces to expose the coarse aggregate and leave a roughened
surface to provide a key. Apply a layer of cement grout on the joint surface prior to pouring fresh
concrete against a construction joint.
[Note:
This is done to ensure aggregate interlock at the joint face; the most satisfactory results are generally
obtained by carrying out the preparation while the concrete is still green.
Methods of removing laitance are normally either brush with water spray or pressured water jet.
Timing of the operation is critical.
Attempts to produce a suitable finish after the concrete has hardened will often be unsatisfactory
because of inadequate exposure of the aggregate, high cost, or tendency to fracture the coarse
aggregate. For vertical surfaces (e.g. stop ends) expanded metal mesh can be an alternative
method of providing a roughened face, although for water-resistant concrete particular attention is
required to ensure that the joint is properly formed and that the form does not itself provide an entry
route for water.
Details and locations of construction joints and pour sizes should be agreed well in advance of any
construction. Construction joints should be positioned and formed to suit the structure.
For further guidance, refer to publications by Concrete Society, British Cement Association ‘Large Area
Pours for Suspended Slabs’ and Technical Report No 34 Concrete ground floors: their design,
construction and finish, etc.]
4.7
S4.7
Not In Use
Concreting in Hot Weather
Comply with the recommendations of SS 544-1, Clause A.8.2 (Delayed ettringite formation),
and Clause A.9.3 (Work in hot weather), and refer to SS EN 206, Clause 5.2.9 and SS 544-2,
Clause 5.4 (Concrete temperature) where appropriate.
Cool formwork made of metal, concrete or other material with water before placing concrete against it.
Ensure no standing water is left in formwork.
4.8
Pours with Temperature Control
In pours, when temperature control measures are necessary to achieve the performance
requirement of crack control due to temperature and shrinkage, mentioned in Section C3010:Clause:2.2, or when rich mixes are to be placed at high ambient temperatures, or when directed
by the SO, take actions on the following:
(a)
Propose suitable methods to SO for acceptance to ensure the temperature of the concrete does not
exceed 70°C during hydration.
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(b)
Control the temperature gradient across the section by the provision of thermal insulation to prevent a
differential greater than 20°C.
(c)
Monitor the temperature of the concrete through the section.
(d)
Continue temperature monitoring until the hottest part of the section is less than 20°C greater than the
minimum daily ambient temperature.
(e)
Protect the concrete from abrupt changes in temperature at the end of the curing period.
(f)
Inspect and remove any bleeding water and weak concrete at the top surface prior to the setting of
concrete. Replace surface concrete and re-compact if necessary.
Propose for SOs acceptance on adjustment of the limits on temperature differential taking into
consideration the assessment of information concerning the aggregate type and its effect on the
thermal coefficient of expansion of the concrete.
[Note 1: In some practice, a concrete temperature limit is 65ºC instead of 70ºC.]
4.9
S4.9
Not In Use
Control of Early Age Thermal Cracking
When concrete is to be placed in conditions or in an element where early age thermal cracking is
likely, all reasonable measures shall be adopted that minimise the risk of early age thermal cracking
to a level acceptable to the SO.
Where a risk of thermal cracking is identified, the location of monitoring apparatus and interpretation of
the values recorded shall be agreed with the S.O. prior to installation.
Where cracking occurs that it is expected will result in corrosion of the reinforcement, unacceptable
water leakage, impaired durability or reduced structural adequacy, it will be rectified as agreed with the
SO.
Unless otherwise specified in table below, isolated crack in general reinforced concrete superstructure
shall be limited to 0.3 mm wide.
Location
Crack width
Water tight structures
0.2mm
Note: All parties should be aware that concrete will crack and that in most cases this is not
harmful. The 0.3 mm surface crack width limit for superstructures is taken from NA to SS EN 19921-1:2004 Table NA 4.
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4.10
Protection from Rain
Protect the concrete during transportation and after placing using tarpaulins, polythene sheeting etc.
If heavy rain commences during concreting or as directed by the SO, implement appropriate protection
measures before continuing.
4.11
Concrete Finishes
All concrete formed and unformed finishes shall be classified Basic, Ordinary, Plain and Special
Concrete finishes in accordance with BS EN 13670.
4.11.1
S4.11.1.1
Not In Use
Formed Finishes
Unless otherwise specified in the drawings or directed by the SO, formed concrete finishes shall be
Ordinary Finish in accordance with BS EN13670.
Prepare a sample of the specified formed finishes at the start of the Contract for SO’s acceptance,
and to be kept and used as a reference throughout the duration of the Contract.
Note:
It is important not to 'over-specify' the quality of finish, particularly where it is covered over by following
work. All finishes assume that the concrete is fully compacted.
The 'normal' finish assumed for all work is BS EN 13670 Ordinary finish for formed finish. Finishes of
higher quality will usually cost more –but the costs may be offset where no applied finishes are then
required.
A BASIC finish is that normally applicable to such items as sides of foundations and ground beams
etc. where no particular requirement is needed other than to ensure compliance with all other
clauses of the specification such as concrete compaction, cover to reinforcement etc.
ORDINARY finish: This is for use where visual quality is not important or it is to receive applied
finishes. It is recommended that this finish is not used where surfaces are only to be painted. The
use of small panel forming systems is considered suitable for producing this finish. Joints between
formwork panels will show and the step may be up to 5 mm. grain marks are generally due to slight
absorbance variations causing local colour variation, but the surface is generally smooth. Panels and
blot holes may not be in a regular pattern. Colour of the finish will vary with the concrete delivered,
the release agent used and reuse of the forming material. Project sample panels should not be
specified for this finish. As the concrete finish is not important visually, making good is acceptable and
so blowholes and minor surface blemishes can either be dealt with or accepted untreated by
agreement between the SO and Constructor based on achieving an overall standard similar to the
reference panels. If a system formwork is to be used, the finish off the formwork will generally be
acceptable and the SO is expected to be aware of its quality.
PLAIN finish is for use where visual quality is of some importance such as areas occasionally seen or
to be directly painted. The use of sheet material to limit jointing in forming material is considered
suitable for producing this finish. In any one visible elevation the sheets should be of the same type
and have had the same number of previous uses. Joints between formwork panels will show and the
step may be up to 3 mm. Tie-bolt holes should ideally be recessed,
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or alternatively filled flush, although this may not be so aesthetically pleasing. Panels and bolt holes
should be in a regular pattern. Colour of the finish will change with concrete delivered and reuse of
the forming material. A special project panel should not be specified for this finish, but a project
example should be produced as one of the first areas of concrete poured on the project and used as
the benchmark for the rest of the concrete.
SPECIAL finishes should be specified for in the architectural formed finishes and when a worked
finish is required. Sample panels will be required using the forming system and concrete to be used
on the project for producing the particular finish. The size and complexity of the sample should be
agreed to test the project detail and confirm that the execution can produce the finish on a repetitive
basis will be a special finish to a particular requirement. A site sample is necessary.
Where this is required, there needs to be clear understanding of what is needed. Particular care is
necessary in the selection of concrete and formwork materials, and in consideration of placing,
compacting etc.
Specification considerations for producing special finishes:
a. Required surface regularity must be achievable
b. Allowable colour variation of the surface based on generic colour of the concrete.
c. Extent of acceptable blowholes. These depend on formwork type, concrete, release agent and
compaction – some blowholes are inevitable.
d. How much making good may be expected – some is inevitable
e. Arris type required
f. use of cover spacers
g. arrangement of formwork joints and tie holes (filled but ideally recessed)
h. Location of a ‘sample’ or similar finish
a. special tolerances – must be achievable
j. light reflectance
Where finishes to precast beams and slabs are required to allow in‑situ concrete to act compositely,
these areas to be clearly identified and described.
Where surface finishes to concrete are required to be smooth and level to provide bearings for
precast slabs or beams these areas shall also be clearly identified and described.
For further information on special finishes refer to NSCS Guidance.
S4.11.1.2
Basic Finish
There are no requirements for finish other than to enable adequate compaction, to provide adequate
cover to reinforcement and to achieve specified tolerances
S4.11.1.3
Ordinary Finish
There are no special formwork requirements for this finish, Concrete should be thoroughly compacted
and the formed surface should be free from major inherent blemishes and honeycombing. There is
no requirement for consistency of colour for the struck surface. Surface defects may be made good
subject to agreeing a method with the SO. Steps at joints between forms to be a maximum of 5 mm.
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S4.11.1.4
Plain Finish
A plain concrete finish requires the careful selection of the concrete, release agent, and the use of
good quality formwork. The concrete must be thoroughly compacted and all surfaces should be true
with clean arrises. Only very minor inherent surface blemishes should occur, with no discolouration
from the release agent or grout runs from adjacent pours. The struck surface should be of a
consistent colour from the materials used. The arrangement of formwork panels and tie-bolt holes
should be in a regular pattern. Steps at joints between forms to be a maximum of 3 mm. It is
expected that this finish will not require making good.
S4.11.1.5
Special Finish
A special finish requires the careful selection of the concrete, release agent, the use of good quality
formwork and through compaction.
Special finishes (other than formed or unformed, basic and ordinary finishes) are required as follows:
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S4.11.2.1
Unformed Finishes
Unless otherwise specified in the drawings or directed by the SO, unformed concrete finishes shall be
Basic Finish.
[Note 1: Some practice uses ‘Brushed Finish’. Brush surface of concrete while still green, with a stiff
broom or wire brush to produce a lightly textured surface. Bristles shall be 1.6 mm diameter unless
otherwise agreed by the SO. Brush consistently and continuously across each area designated.]
Note:
Basic finish: This is normally applicable for areas to receive a levelling or wearing screed. A closed
finish produced by levelling, and use of a skip float or similar process. Float marks and ridges will occur.
No further work is required.
Ordinary finish: This is for use in areas to receive flooring materials, types of false floor or other
raised finish. It may not be suitable for thin vinyl flooring without grinding or an underlayment. If thin
vinyl with minimum additional work is required, a Plain finish should be specified. This is a level
uniform surface produced typically by hand or power floating but not by skip float or similar process.
The finish is to be free from ridges but fine float marks are to be expected. This may be acceptable
for the application of finishes such as tiles or carpet.
Plain finish: This is for use in areas without any other finish other than paint or surface coatings, and
provides a dense smooth surface typically produced by hand or power trowelling. This may be
suitable for directly trafficked surfaces – see BS 8204: Screed, cases and in-situ flooring.
Special finish: This is for industrial floors, areas of special trafficking or areas requiring a specific
texture (e.g. tamped or brushed), and can be produced by further working other finishes. This is
a finish where special requirements have to be given.
Where power finishing is not practically possible or not permitted due to working time restrictions, there
is a risk of reinforcement ripple occurring if using a skip float. A thin bonded smoothing compound may
be necessary in the situation where a smooth wearing surface is required, or an underlayment can
be used where a thin flooring material is to be laid.
Where the element is to provide a smooth wearing surface or to receive directly applied flooring
without the need for a levelling screed, the regularity should comply with the requirements of BS 8204-2
or Concrete Society publication TR34 Concrete Industrial ground floors – A guide to their design and
construction.
S4.11.2.2
Basic Finish
The concrete shall be levelled by skip float, or similar process to produce a closed uniform surface. No
further work shall be carried out.
S4.11.2.3
Ordinary Finish
The concrete shall be finished by floating or panning or a similar process, to produce a level, uniform
surface. No further work shall be carried out.
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S4.11.2.4
Plain Finish
The concrete shall be finished by trowelling or a similar process, to produce a dense, smooth, level,
uniform surface. No further work shall be carried out.
S4.11.2.5
Special Finish
To be produced by further working of a finish or other improvements as specified herewith.
4.11.2
Not In Use
4.12
Curing and Protection
4.12.1
Not In Use
S4.12.1
Curing
Cure the surface of the concrete to avoid premature drying-out. Methods of curing shall be in
accordance with BS EN 13670, Clause 8.5 (Curing and protection) and as agreed with the SO.
On completion of compaction and operations on the concrete, the surface shall be cured without
delay. Commence curing immediately after compaction: protection from radiation to be in place
within 30 minutes of final tamping.
Curing membranes shall be compatible with any finishes to be applied subsequently. The duration of
applied curing shall be a function of the development of the concrete properties in the surface zone.
Unless otherwise directed by the SO or shown in the drawings, propose for the SO’s acceptance
on the curing class to be used. The curing classes shall be as defined by curing period or
percentage of the specified characteristic 28 days compressive strength, according to Table 4, BS
EN 13670.
Refer to BS EN 13670 Annex F Table F.1 for curing time. In any case, cure time shall not be less
than 3 days after casting.
S4.12.2
Protection
Protect the structure against damage. Propose methods for the repair of any damage occurring
to make good subject to the agreement of the SO.
S4.12.3
Early age thermal cracking
When concrete is to be placed in conditions or in an element where early age thermal cracking is
likely, measures shall be adopted that minimise the risk of early age thermal cracking to a level
acceptable to the SO. Ensure that the temperature of the concrete does not exceed 65°C and that
the temperature differential does not exceed the appropriate values given in CIRIA report C660
(Bamforth 2007), Table 7.1. Where a risk of thermal cracking is identified, the location of
monitoring apparatus and interpretation of the values recorded shall be agreed with the SO prior to
installation.
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4.12.2
Not In Use
4.11.2.1
Not In Use
4.11.2.2
Not In Use
4.13
Not In Use
S4.13
Accuracy of Construction
Propose and submit to the SO for acceptance on the permissible deviations for the corresponding
works or structure to be undertaken, and specific items or elements or part of the structure where
tighter accuracy shall be required.
Carry out regular checks on the accuracy of the structure and if a part of the structure is found to be
out of tolerance, propose any remedial work required.
The following are the permitted tolerances for the structure as defined on the drawings. These
tolerances take precedence over BS EN 13670. The tolerances for position refer to the tolerance
from the reference lines and datum. Any deviation in secondary lines is included in the tolerances
given.
Note: It is important that ambiguity in the specification of permissible deviations is removed in order to
avoid possible disagreements at a later stage.
The values given below are obtained from the UK National Structural Concrete Specification for
Building Construction for guidance only. The following values take precedence over those given in
BS EN 13670. They are practical values which are believed to be sensibly achievable on site.
There may be cases where tighter values are needed – but there will usually be a cost associated
with this. Further guidance on dimensional deviations for in-situ concrete can be found in Table 1
of BS 5606:1990.
4.13.1
S4.13.1
Not In Use
Hierarchy of Specified Permissible Deviations
The hierarchy of tolerance adopted in this specification is such that the tolerance of each level must be
contained within the tolerances level of the level above where 1 is the highest level: First – the overall
tolerance of the structure
Second – the positional tolerance of all parts of elements of the structure within the overall tolerance
Third – the dimensional tolerance of the individual elements within their positional tolerance Fourth –
the opposition tolerance of reinforcement and fixings within the individual elements dimensional
tolerance clause
4.13.2
Size of Elements
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4.13.2.1
Slab thickness
Permitted deviations on slab thickness shall be as given in Table 2.
Table 2. Permitted deviations on slab thickness
Thickness, t (mm)
4.13.2.2
Permitted deviation, D (mm)
Up to and including 150
±6
Over 150 up to and including 600
± 10
Over 600 up to and including 1000
± 15
Over 1000
± 20
Formed elements
The linear dimension L of formed elements (including beams, columns, walls, openings) shall be
accurate to be kept within the values given in Table 3 and as illustrated in Figure 1 where L is
length, height or width of element in the direction considered.
Table 3. Permitted deviations on formed elements
L
Permitted deviation, D (mm)
Up to and including 600mm
8
Over 600mm up to and including 1.5m
10
Over 1.5m up to and including 8m
15
Over 8m up to and including 15m
20
Over 15m up to and including 30m
30
Over 30m
30 + 1mm per metre or part over 30m
Figure 1
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4.13.3
Twist of Elements
The distance from any one corner to the plane containing the other 3 corners to be accurate within the
values given in the Table 4 and as illustrated in Figure 2.
Figure 2
Table 4. Permitted deviation ontwist of elements
L
4.13.4
Permitted deviation, D (mm)
Up to and including 600mm
±6
Over 600mm up to and including 3m
± 10
Over 3m up to and including 8m
± 15
Over 8m
± 15 + 2mm per metre or part over 8m
Squareness of elements
Permitted deviation on squareness of elements shall be within the values given in Table 5 and as
illustrated in Figure 3.
Figure 3
Table 5. Permitted deviation on squareness of elements
L
4.13.5
Permitted deviation, D (mm)
Up to and including 600mm
±6
Over 600mm up to and including 2m
± 10
Over 2m up to and including 4m
± 15
Over 4m
± 15 + 1mm per metre or part over 4m
Position on Plan
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4.13.5.1
Foundations
Permitted deviation for position on plan of any element of the foundation relative to the intended
position = ± 30 mm as illustrated in Figure 4.
Figure 4
4.13.5.2
Elements above foundation
Permitted deviation for position on plan of any element above the foundation relative to the intended
position = ± 10 mm measured at floor level as illustrated in Figure 5.
Figure 5
4.13.5.3
Edge of slab
Permitted deviation of position on plan of slab edges is relative to the intended position = ± 10mm
measured at floor level.
4.13.6
Level of Elements
The following tolerances are for surfaces that will receive further levelling finishes and are prestrike.
4.13.6.1
Intended level
Permissible deviation from intended level = ± 10mm
4.13.6.2
Top of foundation
Permissible deviation of the top surface of any foundation = ± 25 mm
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4.13.6.3
Level of intersecting beams
Permissible deviation of beams intended to be at the same level = + 10 mm
Level between 2 points 6 m apart
Permissible deviation 10 mm as illustrated in Figure 6.
Figure 6
Any point under a 3 m straight edge
Permissible deviation for any position on floor 6mm as illustrated in Figure 7.
Figure 7
4.13.7
Cast-in Fixings
Permissible deviation from intended position = 6mm as illustrated in Figure 8.
Figure 8
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4.13.8
Verticality of Elements
Plumb over a height, including beams or edges above each other shall be accurate to within the
values given in Table 6 and as illustrated in Figure 9.
Figure 9
Table 6. Verticality of elements
Height(m)
4.13.9
(mm)
Up to and including 1.5
5
Over 1.5 up to and including 2.5
10
Over 2.5 up to and including 4
15
Over 4 up to and including 8
20
Over 8
20+1mm per metre or part over 8m (to a
maximum of 50mm)
Bow of Elements
Unspecified bow is as measured between extremities.
Permissible deviation shall not exceed the values given in Table 7.
Table 7. Permitted deviation for bow of elements
Length (m)
(mm)
Up to and including 1.5
±5
Over 1.5 up to and including 3
±8
Over 3 up to and including 5
±10
Over 5 up to and including 8
±15
Over 8
±15 +1mm per metre or part over 8m
(with a maximum of 25mm)
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4.13.10
Specified Pre-camber
Permissible deviation shall not exceed the values given in Table 8 and as illustrated in Figure 10.
Figure 10
Table 8. Permitteddeviation for specified pre-camber
Specified camber (mm)
4.13.11
(mm)
Up to and including 20
±5
Over 20, up to and including 40
±10
Over 40
±15
Abrupt Changes to Continuous Surfaces where Finish is not Specified
Permissible deviation shall not exceed 3 mm as illustrated in Figure 11.
= Permitted up to 3 mm.
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4.13.12
Cast-in Foundation Bolts
Preset foundation bolt or bolt groups when prepared for adjustment. Permitted deviation from specified
position as illustrated in Figure 12.
Figure 12
Preset foundation bolt or bolt groups when not prepared for adjustment. Permitted deviation from
specified position as illustrated in Figure 13.
Figure 13
Preset wall bolt or bolt groups when not prepared for adjustment. Permitted deviation from specified
position as illustrated in Figure 14.
Figure 14
4.13.13
Openings for Services
Permitted deviations for openings = +10 mm for size and ±25 mm for location.
4.14
Premature Cessation after Placing and Compaction
Propose for the SOs acceptance on suitable arrangement for premature cessation of a pour shall be
agreed and in place before work starts. Should premature cessation of a pour arise, agree with SO the
extent and timing of any necessary remedial work before resumption of placing.
5
VERIFICATION AND SUBMISSIONS
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5.1
Compliance Testing
Carry out sampling and testing during concreting operations in accordance with SS EN 206 and SS
544-2.
Agree with the SO on the electronic submission of all test results to the SO as soon as they are
available.
5.1.1
S5.1.1
Not In Use
Delivery Tickets for Ready Mixed Concrete
Delivery ticket information shall be in accordance with SS EN 206-1 Clause 7.3 (Delivery ticket for
ready mixed concrete) and SS 544-2 Clause 11 (Delivery of fresh concrete) to be completed and
available prior to discharge of concrete into the structure. Where the Constructor authorises the
addition of extra water this shall be recorded on the delivery ticket. All delivery tickets shall be retained
by the Constructor until the structure is handed over to the Employer. Where a ticket is marked ‘nonconforming’ a copy shall be passed to both the Constructor and SO within 24 hours of placing the
concrete.
5.1.2
Addition of Water
No water or other materials shall be added to the ready-mix truck mixer drum before discharge, and
comply with SS EN 206 Clause 7.5. In special cases, admixtures, pigments, fibres or water may be
added where:
(a)
this is under the responsibility of the producer
(b)
the consistence and the limiting values conform to the specified values
(c)
there is a documented procedure for undertaking this process in a safe manner within the factory
production control
(d)
if water is added, a conformity control shall be carried out on a sample of the final product.
The quantity of any water, admixtures, pigments or fibres (if the content of fibres is specified), added
to the truck mixer shall be recorded on the delivery ticket in all cases. And the concrete shall be remixed until the added constituent has been completely dispersed throughout the batch of load and,
in the case of an admixture, has become fully effective.
5.1.3
Not In Use
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S5.1.3
Compression Testing of Concrete Cubes
Test concrete cubes in an independent accredited laboratory. Testing of
fresh concrete shall be in accordance with BS EN 12350.
Concrete test cubes shall be manufactured, initially cured and subsequently transported to an
independent accredited SAC SINGLAS laboratory in accordance with BS EN 12390-2, for testing in
accordance with BS EN 12390.
5.1.3.1
Electronic Tagging of concrete cubes
Unless otherwise agreed with the SO, all concrete cubes are required to be electronically tagged
to allow accurate tracing of the cube samples. Propose suitable electronic tagging system for SOs
acceptance.
Propose and provide an electronic recording system with the following capability:
5.2
(a)
Relevant data can be authenticated at the request of the SO
(b)
Results can be transmitted to the SO via the internet system, within 3 hours of the test
(c)
Data management software is supplied and capable of providing analysis of the results, including
standard deviation computations. The software shall also be capable of displaying the cube testing data
and analysis graphically.
(d)
All data can be compiled and electronically submitted to the SO at the end of the project.
Delivery Tickets for Ready Mixed Concrete
Delivery ticket information shall be in accordance with SS EN 206 Clause 7.3 (Delivery ticket for
ready mixed concrete) and SS 544-2 Clause 11 (Delivery of fresh concrete) to be completed and
available prior to discharge of concrete into the structure.
5.3
Inspection
5.3.1
Inspection Before Concreting
Inspect the formwork, spacers, fixed reinforcement and inserts before placing the concrete. Allow
concrete to be placed only when the works are inspected and satisfactorily accepted by the SO.
5.3.2
Inspection After Concreting
Inspect the concrete after the specified curing period. Identify any remedial work required and submit
proposal of rectification for agreement by the SO.
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5.4
Temperature Control
Provide evidence that the temperature of the concrete will not exceed 70°C during hydration
where large sections and/or rich mixes are being used.
5.5
Assessment of In-situ Compressive Strength
Propose for the SOs acceptance an in-situ concrete testing schedule on the test types, locations, the
number of tests and test standards to be carried out.
Carry out assessment of in-situ compressive strength as indicated in the schedule, drawing or as
directed by the SO, and carry out the assessment in accordance with SS EN 13791.
Carry out assessment of characteristic in-situ compressive strength by testing of cores or indirect
methods in accordance with SS EN 13791 to the concrete structure as indicated in the schedule or
as directed by the SO.
S5.6
Non-Destructive Testing
Carry out non-destructive tests as indicated in PSD. Carry out the tests in accordance with the
relevant parts of SS 78, BS EN 12350, BS EN 12390, BS EN 12504, SS EN 13791 Cl 9
and SS 592.
S5.7
Action in the Event of Non-conformity
Any test or inspection reports that show that any part of the structure does not meet the specified
criteria shall be reported to the SO, as soon as the results are available.
Provide proposals for dealing with the non-conformity to the SO within five working days of reporting the
results. SS EN 13791 Cl 9 and SS 592 provide guidance on the situation.
A course of action shall be agreed within a further five working days.
The cost of all additional testing and remedial works shall be at the Constructor’s expense.
S5.8
As-Built Drawings
Obtain authority approved plan from SO; update the plan to capture all deviations or amendments, if
any, including those captured in SO’s Instructions (SOIs), Project Manager’s Instructions (PMIs),
Architect’s Instruction (AIs), Engineer’s Instruction (EIs), Request for Informations (RFIs), etc.; submit
the plan as as-built drawings to SO for record and authority record plan submission. The as-built plan
shall be submitted progressively floor by floor not later than two weeks from casting date.
S6
Added clause
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(12) C03-020 Reinforcement
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1
GENERAL
Read this Section with G01-010 "General Requirements" and all other contract documents.
1.1
Scope
This Section covers general requirements for bars and welded fabric reinforcements used in reinforced
concrete elements.
1.2
Related Sections
Read this Section in conjunction with the relevant requirements of the following sections:
C03-010
Concrete Construction Generally
C03-060
Precast Concrete Works
C03-070
Prestressed Concrete Works
C03-080
Concrete Repair
C05-010
Structural Steelwork
C05-020
Protective Works for Structural Steelwork
1.3
Standards, Codes, Regulations and Technical References
1.3.1
Not In Use
S1.3.1
Standards and Codes
Unless otherwise agreed by the SO, ensure all of the Works comply with the relevant requirements of the
standards and codes listed below or referenced in the body of the Specification. Alternative standards and
codes may be proposed for approval by the SO, provided it can be demonstrated that the alternative
standards and codes comply with the requirements of the standards specified. All standards and codes
quoted are the current version, unless specific year references are noted.
In the event that the standards or codes are partially superseded or have become obsolete, refer to the
current edition or the approved substitution for the relevant clauses.
Singapore Standards
SS
EN1992-11
Eurocode 2: Design of concrete structures, Part 1-1 General rules and rules for buildings
SS
EN1992-2
Eurocode 2: Design of concrete structures – Part 2: concrete bridges – Design and detailing rules
SS
EN13670
Execution of concrete structures
SS
ISO Steels for the reinforcement of concrete.Reinforcement couplers for mechanical splices of bars –
15835-1
Part 1: Requirements
SS
ISO Steels for the reinforcement of concrete. Reinforcement couplers for mechanical splices of bars –
15835-2
Part 2: Test methods
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SS
ISO Steels for the reinforcement of concrete. Reinforcement couplers for mechanical splices of bars –
15835-3
Part 3: Conformity assessment scheme
SS 560
Specification for steel for the reinforcement of concrete – Weldable reinforcing steel – Bar, coil and
decoiled product
SS 561
Specification for steel fabric for the reinforcement of concrete
SS CP83
Construction computer-aided design (CAD)
SS 566
Specification for steel for the reinforcement of concrete - Plain bars
Other Standards
BS
EN Steel for the reinforcement of concrete – Weldable reinforcing steel - General
10080
BS
EN Steel for the reinforcement and prestressing of concrete. Test methods. Part 1: Reinforcing bars,
ISO15630- rods and wire
1
BS
EN Steel for the reinforcement and prestressing of concrete. Test methods.Part 2:Welded fabric and
ISO15630- lattice girders
2
BS
EN Fibres for concrete – Part 1: Steel fibres – Definitions, specifications and conformity
14889-1
BS
EN Fibres for concrete – Part 2: Polymer fibres – Definitions, specifications and conformity
14889-2
BS
EN Welding – Welding of reinforcing steel – Part 1: Load bearing welded joints
ISO
17660-1
BS
EN Welding. Welding of reinforcing steel. Non load-bearing welded joints
ISO
17660-2
BS
EN Specification and qualification of welding procedures for metallic materials. Welding
ISO 15614 procedure test. Arc and gas welding of steels and arc welding of nickel and nickel alloys
BS
EN Qualification testing of welders. Fusion welding. Steels
ISO 96061
BS
1011
EN Welding. Recommendation for welding of metallic materials. Part 1 General guidance for arc welding
Part 3 - Arc welding of stainless steels
BS 4449
Steel for the reinforcement of concrete – Weldable reinforcing steel – Bar, coil and decoiled product
– Specification
BS 4483
Steel fabric for the reinforcement of concrete – Specification
BS 6744
Stainless steel bars – Reinforcement of concrete – Requirements and test methods
BS 7973
Spacers and chairs for steel reinforcement and their specification Part
1:2001: Product performance requirements
Part 2:2001 Fixing and application of spacers and chairs and tying of reinforcement
BS 8666
Scheduling, dimensioning, bending and cutting of steel reinforcement for concrete –
Specification
BS
ISO Epoxy-coated steel for the reinforcement of concrete
14654
PD 6687
Background paper to the UK National Annexes to BS EN 1992-1
ISO 1460
Metallic coatings — Hot dip galvanized coatings on ferrous materials — Gravimetric
determination of the mass per unit area
ISO 1461
Hot dip galvanized coatings on fabricated iron and steel articles — Specifications and test methods
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1.3.2
1.3.3
Regulations
(a)
Workplace Safety and Health (Construction) Regulations 2007
(b)
Approved Documents issued under the Building Control Act
Technical References
Refer to the following technical reference for guidance in carrying out the Works:
(a)
BCA/IES/ACES Guide book for Site Supervision Plan (2019)
(b)
MOM, Circular on Collapse of Reinforcement Cage for Thick Concrete Slab (01 September 2015)
(c)
CIRIA Report Number 92 Reinforcement Connector and Anchorage Methods
(d)
CIRIA C568 (2001) Specifying, detailing and achieving cover to reinforcement.
(e)
Concrete Society Technical Report No. 51 Guidance on the use of stainless steel reinforcement
1.4
Trade Preamble
1.4.1
Reinforcement Drawings
Produce detailed reinforcement drawings based on reinforcement schedules shown in the drawings. Submit
the detailed reinforcement drawings which shall include information on structural elements, location and
references, to the SO for acceptance prior to construction.
Engage qualified, competent and experienced personnel to prepare the detailed reinforcement drawings
for submission to the SO for acceptance prior to construction.
1.4.2
Workshop Drawings and Bar Schedules
In cases where reinforcement or bar schedules are required, engage qualified, competent and
experienced personnel to prepare workshop drawings and bar schedules prior to construction.
1.5
Definitions and Abbreviations
1.5.1
Definitions
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1.5.1.1
anchorage
Length required for development of design stress in rebars, obtained by providing the required
development length or hook/bends if sufficient length cannot be achieved.
1.5.1.2
bar chair
Used to support and provide the cover for the top reinforcement steel, as joint linking single or multi- layer
reinforced steel bars and welded fabric reinforcement, used concurrently with concrete spacers
1.5.1.3
concrete cover
The least distance between the surface of embedded reinforcement and the outer surface of the concrete
1.5.1.4
coupler
Coupling sleeve or threaded coupler for mechanical splicing of reinforcing bars for the purpose of
providing a transfer of axial tension and/or compression from one bar to the other where:
- a coupling sleeve is a device fitting over the ends of 2 reinforcing bars
- a threaded coupler is a threaded device for joining reinforcing bars with matching threads.
1.5.1.5
lapping
Method of creating a single structural entity from 2 rebar segments by overlapping 2 lengths of a rebar,
then wiring them together to maintain the required continuity of stress in the splice zone.
1.5.1.6
mechanical splice
Complete assembly of a coupler, including any additional intervening material or other components providing a
splice of 2 reinforcing bars
1.5.1.7
reinforcing steel
Steel product with a circular or practically circular cross-section which is suitable for the reinforcement of
concrete.
1.5.1.8
starter bar
Rebar cast into the concrete to give a lapped/mechanical splice connection to provide continuity of reinforcement
across a cold joint or construction joint.
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1.5.1.9
test unit
For testing purposes, a batch is divided into test units with a maximum mass of 100 t. Each test unit
comprises products of the same steel grade and nominal diameter from same cast. The manufacturer
certifies that all products in the test unit originate from same cast.
1.5.1.10
welding
Process of joining 2 pieces of metal together by heating to a suitable temperature with or without the application of
pressure, and with or without the use of a filler material.
1.5.1.11
welded fabric reinforcement
Arrangement of longitudinal and transverse bars, rods or wires of the same or different nominal diameter
and length that are arranged substantially at right angles to each other and factory electrical resistance
welded together by automatic machines at all points of intersection
1.5.2
Abbreviations
No item.
2
PERFORMANCE REQUIREMENTS
2.1
Material Verification
2.1.1
Not In Use
S2.1.1
Reinforcement
Reinforcement shall in general comply with SS CP 83, SS 560 and SS 561.
Check the following and verify that the reinforcements are in compliance with approved drawings and
accordance to specified standards:
2.1.2
(a)
Source of reinforcement
(b)
Mill certificate
(c)
Factory production control (FPC) certificate from an accredited certification body
Couplers
Performance requirements of couplers for the intended purpose shall be in compliance with CIRIA Report
Number 92 on Reinforcement Connector and Anchorage Methods.
In addition, materials testing shall be carried out as tabulated in C03-020:Clause:2.2.
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2.2
Reinforcement Detailing
Reinforcement shall be scheduled and detailed in accordance with SS EN 1992-1-1 and BS 8666, taking
into consideration as a minimum on the following:
(a)
Bar bending - minimum scheduling radii and bend allowances.
(b)
Anchorage and lap length. All reinforcement shall be anchored so that the forces are safely and effectively
transmitted to the surrounding concrete by bond without causing cracking or spalling.
(c)
Arrangement of laps and lapped bars.
(d)
Reinforcement spacing.
(e)
Minimum and maximum reinforcement areas.
3
MATERIALS
3.1
Reinforcing Bars
Only reinforcement bars complying with SS 560 and SS EN 1992-1-1 shall be used.
3.2
Galvanised Reinforcement
Comply with ISO 1461 after cutting and bending. Thickness of galvanised coating shall be in accordance
with ISO 1461.
[Note 1: Former practice uses SS 117 which has been withdrawn.]
3.3
Stainless Steel Bar Reinforcement
Comply with BS 6744 unless otherwise specified or indicated in drawings or agreed by the SO. [Note 1:
Refer to BS 6744 on the guidance on the choice of stainless steel for a given application.]
3.4
Not In Use
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S3.4
Epoxy Coated Bar Reinforcement
Comply with BS ISO 14654, bond classification type 1 or 2 as indicated in the drawings. Handle and fix to
avoid damage to the coating, and avoid exposing the underlying steel.
Note:
Implicit in this specification is the assumption that conventional steel reinforcement will be used. In special
circumstances (e.g. in particularly severe exposure conditions) the use of alternative materials might be
considered and this would need to be referred to in the Project Specification.
These include epoxy coated, galvanised and stainless steel reinforcement and non-ferrous reinforcement
(i.e. fibre reinforced plastics). Where use of these alternative reinforcement materials is considered,
specialist advice is available if required (e.g. Concrete Society Technical Report No. 51 Guidance on the
use of stainless steel reinforcement).
The following references may be found helpful as reference for Epoxy coated Reinforcement, Hot dip
galvanising, PVC coating:
a. Comite Euro-International du Beton (CEB), Coating protection for reinforcement, State of the art report 1995,
Thomas Telford.
b. Non-ferrous reinforcement: Interim guidance on the design of reinforced concrete structures using fibre composite
reinforcement, Inst. Struct. Engineers August 1999.
3.5
Welded Fabric Reinforcement
Comply with the requirements of SS EN 1992-1-1 and SS 561.
3.6
Not In Use
S3.6
Fibre Reinforcement
Comply with BS EN 14889 and to be of type and dosage as included in C3-20-PSD.
3.7
Proprietary reinforcement systems
Proprietary reinforcement systems shall comply with the requirements of SS EN 1992-1-1 and SS 560.
Carry out installation in strict accordance with the manufacturer’s recommendations, subject to
acceptance by the SO.
3.8
Reinforcement Cage
Ensure that the fabrication and erection of reinforcement cages are in accordance with the drawings, and
provide safe design and proper construction of the reinforcement cage to ensure its stability during lifting,
prior to and during concreting.
Temporary lifting design shall be submitted for SOs review and acceptance.
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3.9
Reinforcement Material
All materials and equipment used in reinforcement cage fabrication shall be fit for the intended purpose and
meet design specifications. Materials and equipment shall be designed to conform to relevant Singapore
Standards. Where any material is designed to an international or other standard, an engineer must certify
that it conforms to the relevant Singapore Standard and the use of the material is subject to acceptance of
the SO. Materials and equipment must also be manufactured in accordance with a quality assurance system
that ensures compliance with the design specification.
3.10
Not In Use
S3.10
Couplers
Steel reinforcement couplers for mechanical splices of bars shall comply with requirements of SS ISO
15835-1 and SS ISO 15835-3.
Only straight metric threaded and swaged couplers shall be used. Unless otherwise approved by the SO,
tapered systems are not acceptable for use. The couplers shall be of a type which is simple to install and
can be verified to be installed correctly by visual inspection.
The manufacturer of the couplers shall be certified to ISO 9001 quality assurance, or equivalent, for the
manufacture of couplers. The Supplier/ Installer shall be certified to ISO 9001 quality assurance, or equivalent,
for rebar end processing and for coupler installation.
Carry out installation in strict accordance with the manufacturer’s recommendation, subject to acceptance
by the SO.
All couplers shall be legibly and durably marked with identification of the manufacturer, nominal bar size
intended for and clear stamp of the batch or heat number. The batch or heat number shall be traceable to
the original cast. The relevant material mill certificates for couplers shall be submitted with each delivery. The
certificates shall show the salient material properties of the couplers.
Note:
Prepare reinforcing bars adequately to receive couplers. Where threaded couplers are used ensure the
threaded ends are not damaged and that an adequate length of bar is contained within the coupler.
3.11
Not In Use
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S3.11
Spacers
Detail, supply and fix all spacers in accordance to the requirements of BS 7973. Obtain
SO’s acceptance for spacers where the concrete will be exposed subsequently.
Mortar spacers shall have durability and strength characteristics not less than the surrounding concrete.
Note:
Steel spacers within the cover zone may cause corrosion problems subsequently. Particular care is needed
for formed finishes that will be exposed in the completed structure.
Refer also to CIRIA C568 Specifying, detailing and achieving cover to reinforcement, 2001.
4
WORKMANSHIP
4.1
Conditions of Rebars
Rebars shall not be surrounded by concrete unless free from mud, oil, paint, retarders, loose rust, loose
mills scale, grease or any other deleterious substance which can be shown to affect adversely the steel or
concrete chemically or reduce the bond. Light surface rust is acceptable unless detrimental to the finished
structure by causing rust staining to adjacent exposed concrete or formwork.
4.2
Storage and Handling
All reinforcement shall be delivered in properly identifiable tagged bundles, mats or prefabricated
assemblies.
Store reinforcement clear of the ground, and protect from mud, oil and other substances that may
adversely affect its use in the works.
Deliver and store steel fabric horizontally.
Reinforcement shall not be dropped from height, mechanically damaged or shock loaded in any way.
4.3
Not In Use
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S4.3
Cutting, Bending and Fixing
Scheduling, dimensioning, bending and cutting of steel reinforcement for concrete shall be in accordance
with BS 8666 and Clause 6.3 SS EN 13670.
The contractor shall allow for temporary safe supports of all reinforcement during fixing, especially for deep
structural elements/sections such as the pilecaps and rafts. Calculations and details of temporary supports
for the reinforcement of any deep structural elements shall be designed by a professional engineer (PE) and
submitted to the SO for record. The cost for the above shall be borne by the contractor.
The contractor shall prepare appropriate bending schedule for the cutting and bending of reinforcement
bars in accordance with the reinforcement drawings. Reinforcement should not be bent or straightened in
a manner which will damage the material.
Reinforcement fixing shall not commence until satisfactory testing of representative batches has been
completed.
Steel reinforcement shall be clean and free from pitting, paint, oil, grease, split concrete or grout, adhering
earth or loose rust, etc. at the time of fixing and concreting.
All laps of fabric and all intersections of bars shall be securely connected with malleable iron wire of suitable
size or by an alternative method approved by the SO.
4.4
Not In Use
S4.4
Tying of Reinforcement.
Unless otherwise shown in the drawings or specified or directed by the SO, tie reinforcement with black
annealed mild-steel 16-gauge tying wire. Tie stainless steel reinforcement using 16 swg annealed
stainless steel wire. Bend all ends away from the concrete face and remove all loose ends before placing
concrete.
Note:
The need to bend the ends of the tying wire away from the surface and remove all loose ends before placing
concrete is of great importance in avoiding subsequent problems of corrosion and spalling.
4.5
Welding of Reinforcement
All work shall be carried out by properly qualified welders using approved procedures.
Permitted only with the prior written approval of the SO. Where permitted, carry out in accordance with BS
EN ISO 17660-1, BS EN ISO 15614 and BS EN 1011.
4.5.1
Welding Procedures
All work is to be carried out by welders properly qualified to BS EN ISO 9606-1 and using approved procedures.
4.5.2
Welding of Galvanized Reinforcement
Unless otherwise agreed by the SO, welding of galvanised reinforcement is not permitted.
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4.5.3
Welded Lap Joints
Welding joints in parallel bars of the principal tensile reinforcement shall be staggered.
Welding shall be avoided on joints where imposed loads is predominantly cyclical; and at bends.
4.6
Not In Use
S4.6
Laps and Splices
No splices shall be made in the rebar except where shown on the drawings or where accepted by the SO.
In such splices, the rebar shall be placed in contact and wired. Splices in adjacent bars shall be staggered.
Laps shall be in accordance to SS EN 1992-1-1 Clause 8 and BS 8666 as appropriate. Lap
reinforcement shall be as shown in the drawings unless otherwise agreed with the SO.
4.7
Chairs and Spacers
Chairs and spacers shall be suitable for achieving the specified cover to the reinforcement. Concrete and
cementitious spacers shall have at least the same strength and the same corrosion protection as the
concrete in the structure.
4.8
Not In Use
S4.8
Deviation in Concrete Cover and Lap lengths
Rebars shall be secured against displacement outside the specified limits in accordance with SS EN 1992-11, Clause 4.4.1.3. Deviation in concrete cover and lap lengths also shall comply with the requirements
specified in SS EN 13670.
Before concreting, check thoroughly that the specified cover dimensions have been complied. Note:
Allow for additional cover where surface treatment will reduce the as-cast value
4.9
Couplers Requirement
All couplers shall be free from rust or foreign material on the inside surface.
Types of couplers used shall be simple to install and the correctness of installation shall be verified by quick
visual inspection and to have achieved a connection providing the required full strength of the parent bars.
The required torque/swag shall be established and verified on site and submitted for approval by the SO.
Couplers shall be internally greased and covered with plastic caps to a protection detail acceptable to the
SO.
4.10
Not In Use
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S4.10
Cages for Precast Units
Make up cages and fix securely in accordance with the reinforcement drawings to provide adequate rigidity
and to ensure that the specified cover and fit within the moulds are achieved.
Reinforcement not exceeding 12 mm in diameter which projects from the face of the units may be bent to
facilitate the casting or demoulding of the unit subject to approval by the SO for each case. Bending shall be
in accordance with BS 8666 and Clause 6.3 BS EN 13670.
4.11
Exposed Reinforcement
In the event that reinforcement is expected to be exposed for a prolonged period over 3 months or such that
loose rust and scale form, apply a corrosion protection coating for the SOs acceptance. Ensure the coating is
compatible with the concrete and does not reduce the bond of the reinforcement.
4.12
Anchorages
Protect all steel parts from corrosion and keep all threaded parts protected until used. Keep all
devices free from any coating or contamination.
Anchorages, including buried dead anchorages, shall be fixed with due regard to cover requirements for
corrosion resistance and fire protection.
4.13
Inspection and Supervision
Proper inspection and supervision procedures for reinforcement cage fabrication shall be established and
agreed upon by the SO, and complied with in all phases. A proper and timely inspection and supervision
regime shall be in place to ensure that all design requirements laid down in the specifications and structural
drawings are complied with in construction; and to check that the completed portions of the structure are in
compliance with the Specification.
Reject the use of materials that do not conform to the Specification requirements and are not in
accordance with the drawings or have resulted from improper construction.
Material testing, including chemical test, tensile test, shear test, bend and rebend test, shall be conducted
by an accredited laboratory that has appropriate and relevant accreditation for the tests. Inspection and
supervision of reinforcement works shall be extended to the selection of samples for testing, to perform
intermittent or spot checks and to check test results.
S4.14
Ground Bearing Slabs
Where these are reinforced with a single layer of fabric in the upper part of the slab, the fabric may be
placed in position on top of the first compacted layer of concrete, followed by the top layer of concrete,
placed within 30 minutes of the first layer.
Note:
It is important to ensure that the reinforcement ends up in the intended position; the strategy suggested
here, provided the top layer is placed within the specified timescale, should prevent the mesh being trodden
down into the slab depth.
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S4.15
Surface Condition
At the time of placing concrete, ensure the reinforcement is clean, free of corrosive pitting, loose rust and mill
scale and other substances that may adversely affect the bond with concrete.
Light surface rust is acceptable unless detrimental to the finished structure by causing rust staining to
adjacent exposed concrete or formwork.
Note:
Light surface rust is often thought of as beneficial in terms of bond, and is readily distinguishable from the
loose scale and rust which reduce the performance.
S4.16
Safe Access for Steel Fixing & Inspection
The Contractor shall include details of his proposed access to, and working platforms at, steel fixing work
faces where the height of the platform exceeds 2m above the general level.
5
VERIFICATION AND SUBMISSION
5.1
Not In Use
S5.1
Information for Execution
Prior to putting the reinforcement on site, provide mill certificate to confirm that each batch of steel and mesh supplied
to the site complies with BS EN 10080, SS 560, SS 561 or SS 566 as appropriate. Include information such as country
of origin and the name of supplier for review.
Following is a summary of the information that shall be included into the execution specification and method
statement to be submitted for the SO’s acceptance:
(a)
Types of reinforcement
(b)
Permitted types of anchorages or couplers
(c)
Cutting and bending schedules or identify that this is a task for the contractor
(d)
Mandrel diameter for bending bars
(e)
Mandrel diameter for welded reinforcement and fabric bent after welding
(f)
Any requirements to straighten bent bars
(g)
Provisions for welding of reinforcement
(h)
Specifying if spot-welding is not permitted
(i)
Position of reinforcement, including cover, the position of laps and joints
(j)
Special requirements, if any
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(k)
5.2
Nominal concrete cover
Method Statement
Prior to procuring any material and execution of the Works, submit and seek acceptance of the SO on
procedure of fabrication, means of access (at height), lifting design and temporary stability proposal, and
including on method statements and proposals as follows, where applicable:
5.3
(a)
Provision of scaffolding access
(b)
Provision of access openings for thick slab reinforcement fabrication
(c)
Equipment and lifting plans
(d)
Method of temporarily securing/ supporting of reinforcement cage
(e)
Training and documented instructions
(f)
Equipment for fabrication, lifting, and installation
(g)
Methodology - erection and fabrication
(h)
Provision for fall prevention / protection
(i)
Storage and maintenance of components
Material Testing
Unless otherwise agreed and approved by the SO, Table 1 gives the test type, method, frequency and
conformity criteria for material testing:
Table 1. Material testing
Material Type
Steel Reinforcement
Type of
Test
Tensile
No. of
Samples
per Test
Test
Method
Acceptance
Criteria
Testing
Frequency
BS EN
ISO
15630-1
SS 560
Under 20
mm
1 sampling
set at
beginning
of project
and at
every 100t
or part
thereof
3 pieces per
size
SS 560
Clause
8.2.3.1
20 mm to
40mm
1 sampling
set at
beginning
of project
and at
every 500t
or part
thereof
1 piece per
size
SS 560
Clause
8.2.3.2
Bend &
Rebend
Conformity
Criteria
Remark
Mill
certificate
and FPC
certificates
for each
batch to be
kept at site
for each
Batch
delivered
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Bond
Over
40mm
1 sampling
set at
beginning
of project
and at
every
1000t or
part thereof
1 piece per
size
SS 560
Clause
8.2.3.3
Chemical
1 sampling
set at
beginning
of project
and at
every
3000t or
part thereof
1 cast
analysis for
Chemical
Composition
Analysis
SS 560
Clause 7.1
15 pieces
per fabric
size (1
sheet
1mx1m per
fabric size)
.
Mill
certificate
and FPC
certificates
for each
batch to be
kept at site
for each
batch
delivered
Grade
500B > 540
N/mm²
Coupler
specification
for each
type/brand
to be kept at
site and
endorsed by
qualified,
competent
and
experienced
PE.
Tensile test
Welded Steel
Fabric
Reinforcement
Couplers for Mechanical
Static
Tensile
Splices of Steel
Reinforcement (Category
B)
BS EN
ISO156302
SS 561
1 test unit
at
beginning
of project
and at
every 25t
ISO
15835-2
SS ISO
15835-1,
2 sample
1 test per
sets per
sample set
coupler
type & size
at beginning
of project
and at
every
subsequent
200
couplers
SS ISO
15835-3
Permanent/
Elongation
Slip
Grade
600B > 648
N/mm²
SS ISO
15835-1
Clause
5.4.2
.
SS ISO
15835-1
Clause
5.3.3
.
SS ISO
15835-1
Clause
5.5.2
.
SS ISO
15835-1
Clause 5.6
.
(Up to 60%
Fyk)
Ductility
Couplers for Mechanical
Splices of Steel
Reinforcement(Category
F)
high-cycle
fatigue
loading test
(Optional)
Couplers for Mechanical
Splices of Steel
Reinforcement(Category
S)
low-cycle
loading test
(Optional)
1 test set
per coupler
type/brand
& size
1 control bar
per sample
set
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5.4
Safe Work Procedure
A Safe Work Procedure (SWP) for the fabrication and installation of reinforcement cage shall be prepared
by a suitably qualified, experienced and competent PE, and submitted to the SO for acceptance. The
SWP shall include:
5.5
(a)
identifying the work that is high risk construction work
(b)
stating hazards relating to the high-risk construction work and risks to health and safety associated with
those hazards
(c)
describing the measures to be implemented to control the risks
(d)
describing how the control measures to be implemented, monitored and reviewed.
Risk Management
Submit to the SO, the risk management and assessment study in identifying, evaluating and controlling
risks on hazards associated with work involving the fabrication, installation, and lifting of reinforcement cage.
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1
GENERAL
Read this Section with G01-010 "General Requirements" and all other contract documents.
1.1
Scope
This Section covers the requirements for the design, erection, use, alteration and dismantling of the
formwork and falsework structure for reinforced concrete structures.
1.2
Related Sections
Read this Section in conjunction with the relevant requirements of the following section:
C03-010
1.3
Standards, Codes, Regulations and Technical References
1.3.1
Not In Use
S1.3.1
Standards and Codes
Unless otherwise agreed by the SO, ensure all of the Works comply with the relevant requirements of
the standards and codes listed below or referenced in the body of the Specification. Alternative
standards and codes may be proposed for approval by the SO, provided it can be demonstrated that
the alternative standards and codes comply with the requirements of the standards specified. All
standards and codes quoted are the current version, unless specific year references are noted.
In the event that the standards or codes are partially superseded or have become obsolete, refer to
the current edition or the approved substitution for the relevant clauses.
Singapore Standards
SS 280-1
Specification for metal scaffoldings – Part 1: Frame scaffoldings
SS 280-2
Specification for metal scaffoldings – Part 2: Modular scaffoldings
SS580
Code of Practice of Formwork
Other Standards
BS EN12812
Falsework – Performance requirements and General design
BS5975
Code of Practice for temporary works procedures and the permissible stress
design of falsework.
CIRIA Report 136
Formwork Striking Times – criteria, prediction and methods of assessment
Concrete Society Technical
Report 52, 1999
Plain formed concrete finishes
Concrete Society Publication, 2nd
Edition 1995
Formwork: a guide to good practice
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1.3.2
Regulations
(a)
Workplace Safety and Health Act 2011 (WSH Act)
(b)
Workplace Safety and Health (Risk Management) Regulations
(c)
Safety Requirements for Formwork Structures, MOM
(d)
Workplace Safety and Health (Construction) Regulations 2007
(e)
Workplace Safety and Health (Scaffolds) Regulations
1.4
Trade Preamble
1.4.1
Contractor’s Submissions and Proposals
Engage qualified, competent and experienced personnel to:
1.4.2
(a)
carry out design and supervision of the formworks and falsework supports in accordance with statutory
requirements and all relevant regulations.
(b)
design shall be endorsed by a Professional Engineer and submit to MOM when required statutorily.
Qualifications of Supervising Personnel
A formwork and falsework supervisor shall be suitably qualified, competent and experienced with
theoretical and practical knowledge of formwork and false structures and received adequate safety and
health training to familiarise himself with hazards associated with formwork and falsework structures of
similar nature, type, size and purposes.
Provide evidence of past relevant experience for all supervising personnel to the SO for acceptance prior
to commencement of the Works.
1.4.3
Quality Control Plan
Submit and work to a quality control plan as agreed with the SO. Refer to Section G01:010:Clause:1.4.7
for guidance.
1.5
Definitions and Abbreviations
1.5.1
Definitions
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1.5.1.1
base plate
A metal component to transfer the load of vertical member to the base; could be adjustable with a screw
jack or other device.
1.5.1.2
brace
Used to provide lateral stability.
1.5.1.3
falsework
A temporary support system used to support a permanent structure formwork while it is not self supporting.
1.5.1.4
fore head
A U-shape housing used to support the joist or the like.
1.5.1.5
formwork
Part of temporary works used to give the required shape and support in-situ concrete.
1.5.1.6
formwork structure
Integrated system of formwork and falseworks.
1.5.2
Abbreviations
No item.
2
PERFORMANCE REQUIREMENTS
2.1
Control Measures for Safety and Structural Integrity
Allow and provide for the integration of all control measures early in the design process to eliminate or,
if not reasonably practicable, minimise risks to health and safety throughout the life of the structure being
designed. All necessary measures to ensure structural integrity and safety shall be factored in and taken
account of, at the concept development phase of a structure when making decisions about the
following:
(a)
Design and its intended purpose
(b)
Possible methods of construction, maintenance, operation, demolition or dismantling and disposal
(c)
Materials to be used
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(d)
Legislation, codes of practice and standards need to be considered and complied with
Refer also to SS 580 and WSH (Construction) Regulations.
2.2
Cambers
Provide all information on cambers to the structural elements such as beams, slabs and cantilevers
indicating the locations and pre-camber in terms of mm or % span in the formwork design and drawings.
Measurements of camber shall be made after initial setting of concrete and before stripping of formwork.
2.3
Loads and Actions
The formwork and falsework structure and system shall be endorsed by a PE and shall allow for all
loads and actions expected to be applied during construction, including loads applied by the following:
(a)
The formwork and falsework deck, supporting members, and formwork and falsework frames.
(b)
Any false decks provided.
(c)
Concrete pouring techniques and method.
(d)
The concrete pour which includes both the weight of the concrete and dynamic factors applied. The
concrete pour rate and pour sequence shall be specified.
(e)
Workers on the formwork deck and false decks.
(f)
Stacked materials.
(g)
Crane lifted materials on both the complete and incomplete formwork or false deck.
(h)
All formwork structures capable of sustaining the total dead load, live load and impact load imposed on the
formwork and falsework structures in compliance with WSH Act and Regulations and SS EN Eurocodes
and standards on safety and application of factors as appropriate.
(i)
Wind actions - all structures for formwork and falsework shall consider and include:
(i)
wind actions or loads on the formwork and falsework structure or system in accordance with SS
Eurocodes, and shall be detailed as provided in SS 580
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(ii)
providing an allowance for wind action or loading for vertical forms.
[Note 1: Refer also to Building Control Act Approved Document on the relevant
standards and codes on wind action.
Note 2: Refer to Code of basic data for the design of buildings. Loading. Wind loads CP 3 Chapter V Part 2, using 33 m/s as the basic wind speed (3 second gust
speed)
Note 3: Refer to Loading for buildings. Code of practice for wind loads - BS 6399: Part
2, using 22 m/s as the basic wind speed (hourly mean speed).]
3
MATERIAL
3.1
General
Only materials that have established properties and are in compliance with relevant Standards shall be
used.
3.2
Formwork and Falsework Use
Provide and construct formwork and falsework in order to contain and execute the concrete works, to give
the required surface finish to the concrete finishes and to provide the stable and secure support
throughout the period of the intended use.
For proprietary formwork and falsework uses, comply strictly to the manufacturers requirement and
recommendations and submit details for SOs acceptance.
3.3
Formwork and Falsework Material
All materials and equipment used in formwork and falsework construction shall be fit for the intended
purpose and meet design specifications. Materials and equipment shall conform to Singapore Standards
or other relevant standards, as appropriate.
Materials and equipment shall be manufactured in accordance with a quality assurance system that
ensures compliance with the relevant accepted standards and design specification. Submit for the SOs
acceptance certification from a PE and evidence that the materials and equipment conform to the
relevant Singapore Standard.
Refer to SS 580 and WSH (Construction) Regulations.
3.4
Testing and Inspection
Provide a suitable system acceptable to the SO to ensure that only materials and components that
comply with formwork and falsework drawings, standards and specification are used at all times. Do not
use materials and components that are damaged, excessively worn or not fit for the intended use or
purpose. Keep records on site.
Provide all necessary testing to demonstrate that the materials and equipment have had their relevant
properties suitable and fit for the intended use or purposes in cases where these are unobtainable
from the standards.
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3.5
Form lining
All lining agents used shall be non-staining, on-structural material to suit the method of construction and
finish required.
3.6
Formwork Ties
Submit proposals for the SOs acceptance on the provision of formwork ties that are rods or bars within
the permanent structure to retain the form robustly against movements during execution of the works
and due to concrete and concreting works.
In water-resisting construction, use ties of a type that does not induce seepage and reduce the waterresistance of the structure.
4
WORKMANSHIP
4.1
Conditions of formwork
Provide and check that formwork is clean and free from debris and water before commencement of
concreting works.
4.2
Joints
All joints shall be sealed and be sufficiently tight to avoid leakage of grout.
4.3
Tolerance
The finished concrete shall be within required tolerances as specified in SS 580 Table 4.
4.4
Block Outs and Cast-in Items
Clear out block-out items after concreting works.
Details and setting-out levels and positioning for any insert / cast-in items shall be checked and verified as
indicated in the drawings.
Resolve any clashes between built-in frame, holes, cast-in items and reinforcement before any concreting
works.
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4.5
Inspection and Supervision
Provide and comply with the established inspection and supervision procedures for the execution class
in accordance to SS EN 1992 on workmanship and reliability for concrete works, as agreed and
accepted by the SO. The procedures shall provide for proper and timely inspection regime that is
applicable and appropriate to the Works as laid down in the Specifications and in the drawings or as
directed by the SO.
Prior to any commencement of concreting works, provide all necessary checks, including endorsement
by the PE who designs the formwork and falsework structure that the structure is erected in
accordance with design and drawings. Submit to the SO, a certificate of supervision of the formwork
and falsework works certifying that the formwork and falsework structure has been constructed and
built in accordance to the approved drawing and is safe for the intended use or purpose.
Refer also to C03-030:Clause:5.5 on managing risks and hazards.
4.5.1
Formwork and Falsework Supervisor
Provide a formwork and falsework supervisor to undertake the inspection and supervision work - carrying
out regular and periodic checks on all phases of the work in progress, as well as on the completed or
partially completed portions of the structure, to assess their compliance to the specifications and the
approved drawings.
The formwork and falsework supervisor or site supervisor for the execution works shall have the authority
to:
4.5.2
(a)
refuse the use of materials which do not conform to the specifications, standards, approved drawings or as
directed by the SO, and those materials which are likely to result in improper construction;
(b)
stop any work in progress which is not in accordance with the approved plans and specifications for the
job. The supervisor shall have the power to order for the removal or repair of faulty construction or for any
construction performed without an inspection.
Alignment and Tolerances of Structure and Its Components.
Provide a formwork and falsework structure or system that shall provide the dimensions, shape, and size
of the hardened or finished form and appearance of the concrete works as specified or indicated in the
drawings.
Provide and execute the formwork and falsework structure or system such that the structure is built to
correct dimensions and shape as specified or indicated in the drawings. The structure or system shall
have adequate rigidity to maintain its shape and dimensional integrity under different types of
construction loads; and shall be stable and robust in ensuring and maintaining accurate alignment of all
members in position at all times.
The formwork and falsework structure or system shall have its dimensions such as width, height and
length of the formwork and falsework calculated precisely and to allow for workmanship and construction,
so that the dimensions of the finished or as-installed members are within the acceptable limits of tolerance
as specified or indicated in the drawings for the intended purpose and use.
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4.6
Striking/Dismantling
4.6.1
Stripping
Carry out the stripping operation in an orderly, progressive manner in accordance with the approved
methods with the acceptance of the SO. Refer also to C03-030:Clause:5.4.
Refer to SS 580 on the minimum period before striking of the form unless otherwise specified in the
drawings or directed by the SO.
[Note 1: Stripping formwork can be one of the most hazardous phases of concrete construction. While
falling objects are the primary hazard, there may also be fall hazards as a result of floor collapse and
manual tasks hazards from a person working in awkward postures, repetitive handling of materials and
equipment. Refer to Formwork Code of Practice SS 580.]
[Note 2: For minimum period before striking of form, refer to SS 580:2012 Table 5 as shown below.
Type of formwork
Minimum period before striking
Vertical formwork to columns, walls and sides of large beams
1 day
Soffit of slabs and beams <500mm thick
3 days
Soffit of slabs < 500mm thick
3 days
Soffit of beams
3 days
Soffit of slabs =500mm thick
Depends on concrete materials
Soffit of cantilever beams and slabs
7 days
Props to slabs and beams
14 days
Props to cantilever beams and slabs
21days
]
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4.6.2
Dismantling
Dismantling of a formwork structure at a work site shall not commence until the concrete is set and the
necessary approval from the SO is granted. The time to remove props or supports to concrete
members in flexure shall be based on the attainment of the design characteristic strength of the
concrete and the approval of the SO.
Subject to the approval of the SO, shuttering shall not be detached until concrete properties are such that
the concrete structure can be fully self-supporting and capable of carrying imposed loads and actions as
intended.
For the assessment of the in-situ strength of concrete, pull-out tests shall be performed or concrete cubes
shall be tested. The concrete cubes for testing shall be cured under the same conditions as the in-situ
concrete, achieved by temperature-matched curing by which cube samples are immersed in water
whose temperature is matched to the structure.
Subject to the acceptance by the SO, proprietary quick-strip systems can be used to allow the removal of
soffit shuttering without disturbing the propping.
Carry out striking with care to avoid damage to arisses and projections. Immediately, put in place
necessary measures to protect some of the concrete works from damage after removal of the forms.
Remove the formwork slowly so as not to induce or impose a shock load on the partly hardened concrete.
[Note 1: In case of slabs and beams, soffit formwork may be removed when the in-situ strength of
concrete is 10 N/mm2 or 2 times the stress to which it will be subjected, whichever is the greater.
Note 2: When concreting in cold weather, the formwork to beam sides, walls and columns, if struck at
early stages the concrete will still be "green concrete" and can be easily damaged.
Note 3: If the formwork is not required elsewhere, leave it in place until the concrete has cooled from its
high early temperature.]
5
VERIFICATION AND SUBMISSIONS
5.1
Method Statement
Submit and seek approval of SO on the sequence of propping/re-propping and back propping, prior to
procuring any material and execution of the Works:
(a)
Materials for falsework and formwork
(b)
Target age and strength of concrete at striking
(c)
Method of determining strength
(d)
Not In Use
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5.2
S(d)
Method to ensure that slabs/beams are not struck understrength/overloaded.
(e)
calculation of imposed loads on lower slabs
System Forms
Submit proposal in full details for SOs acceptance before the system forms are used. Details shall include
the following information:
(a)
Material properties
(b)
Uses
(c)
Training and manufacturers recommendations and instructions
(d)
Design specifications and requirements
(e)
Concrete mix
(f)
Placing methods
(g)
Methods of forming openings
(h)
Methodology for erection and dismantling
(i)
Storage and maintenance of components
(j)
Provision for fall prevention/protection
(k)
Any other specific requirements
Where jumpforming or slipforming and the like are proposed, details of system forms for submission to the
SO shall include at least the following:
(i)
Materials to be used
(ii)
Proposed rate of slip
(iii)
Concrete mix
(iv)
Methods of checking strength during the pour
(v)
Methods of forming openings
(vi)
Details of cast-ins
(vii)
Methods of fixing reinforcement
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5.3
(viii)
Placing methods
(ix)
Procedures for stopping the slip
(x)
Protection
(xi)
Concrete repairs
Submission on Erection and Dismantling for Approval and Permit
Before commencement of the Works, submit and obtain all necessary approvals and permits from
relevant authorities on the erection and dismantling of formwork and falsework structure and supports.
5.4
Safe Work Procedure for the stripping/dismantling operation
A safe work procedure (SWP) for the stripping operation shall be prepared and provided to those
who will be involved in this high-risk activity. The SWP shall see to the following:
5.4.1
(a)
Identify the work that is high risk construction work.
(b)
State hazards relating to the high-risk construction work and risks to health and safety associated with
those hazards.
(c)
Ensure materials dismantled from the formwork structure are removed promptly or stock-piled in areas
where persons are not required to work or pass.
(d)
Ensure protruding nails, wire ties and other forms of accessories not necessary to subsequent work are
pulled, cut or otherwise made safe.
(e)
Describe measures to be implemented to control the risks.
(f)
Describe how control measures are to be implemented, monitored and reviewed.
Submission of SWP
Submit for SOs acceptance the SWP as follows:
(a)
Number of persons in the stripping crew.
(b)
The sequence of stripping activities.
(c)
Details on how the frames and/or other supports to be removed, including how far U- heads are to be
lowered.
(d)
Whether the support system shall be completely removed in a zone prior to removal of the formwork deck.
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(e)
When back-propping is required or only part of the support system shall be removed, how the structural
members shall remain in place and/or the type and layout of members that shall replace the formwork
system.
(f)
Any other special requirements involved in the stripping and/or building process, including the checking of
back-propping after post-tensioning, etc., if applicable.
5.5
Risk Management
5.5.1
Hazards
Undertake and submit for the acceptance by the SO, the risk management and assessment of hazards
associated with work involving the erection, alteration and/or dismantling of formwork that shall include
the following:
5.5.2
(a)
Formwork and falsework collapse before, during and after placement of concrete.
(b)
Falls from heights. Refer to the Code of Practice on Managing the Risk of Falls at Workplaces published
by MOM.
(c)
Slips and trips.
(d)
Falling objects.
(e)
Storage and handling of hazardous materials.
(f)
Movements of heavy vehicles and heavy objects involving crane forklifts, etc.
(g)
Other hazards identified or directed by the SO.
Safe Work Procedure for high risk construction work
Prepare and submit for the acceptance of the SO, safe work procedure for high risk construction work, or
as directed by the SO before the work starts. Identify and submit for the SOs acceptance, a range of
activities that are defined as high risk construction work, including work:
(a)
involving a risk of a person falling more than 3 metres or falling into depth;
(b)
involving demolition of an element of a structure that is loadbearing or otherwise related to the physical
integrity of the structure;
(c)
involving structural alterations or repairs that require temporary support to prevent collapse;
(d)
carried out in or near a confined space;
(e)
carried out in or near a shaft or trench with an excavated depth greater than 1.5 metres;
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(f)
carried out on, in or adjacent to a road, railway or other traffic corridor that is in used by traffic other than
pedestrians;
(g)
execution in SS 580.
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(14) C03-040 Designed Joints
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1
GENERAL
Read this Section with G01-010 "General Requirements" and all other contract documents.
1.1
Scope
This Section covers general requirements for designed settlement and expansion joints, and crack
induced construction joints in concrete structures as in SS EN 1992.
For general requirements of normal construction joints refer to Section C03-010 "Concrete Construction
Generally".
1.2
Related Sections
Read this Section in conjunction with the relevant requirements of the following sections:
C03-010
Concrete Construction Generally
C03-050
Water-resistance to Concrete Structures
1.3
Standards, Codes, Regulations and Technical References
1.3.1
Standards and Codes
Unless otherwise agreed by the SO, ensure all of the Works comply with the relevant requirements of
the standards and codes listed below or referenced in the body of the Specification. Alternative
standards and codes may be proposed for approval by the SO, provided it can be demonstrated that the
alternative standards and codes comply with the requirements of the standards specified. All standards
and codes quoted are the current version, unless specific year references are noted.
In the event that the standards or codes are partially superseded or have become obsolete, refer to
the current edition or the approved substitution for the relevant clauses.
Singapore Standards
SS EN 1992
Design of Concrete Structures
SS560
Specification for steel for the reinforcement of concrete Weldable reinforcing steel - Bar, coil and de-coiled product
Other Standards
1.3.2
BSEN13670
Execution of Concrete Structures
BS ENISO17660-1
Welding of reinforcing steel (load-bearing welded joints)
BS ENISO17660-2
Welding of reinforcing steel (Non load-bearing welded joints)
BS6093
Code of Practice for design of joints and jointing in building construction Guide
Technical References
Refer to the following technical references for guidance in carrying out the Works:
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(a)
CIRIA Report 146 Design and construction of joints in concrete structures
(b)
Concrete Society, Technical Report TR 34 Concrete Industrial Ground Floors - A guide to design and
construction, 4th Edition
(c)
Not In Use
S(c)
ACI, Standard Joints in concrete construction: ACI 224.3R-95
(d)
CIRIA Design for movement in buildings (2014)
1.4
Trade Preamble
1.4.1
Contractor’s Submissions and Proposals
The type of designed joints and locations are indicated in the drawings. Engage qualified and experienced
personnel to propose the following for SOs acceptance:
1.4.2
(a)
Suitable joint materials, including joint fillers and waterproofing element, etc. to comply with the performance
requirements as set out in clause 2.1 below
(b)
Details and construction method to install the joint materials as proposed
Provision of Spare Material
Deliver to the Site in robust protective packages marked for identification, and store where directed,
additional joint materials for minor replacement or repairs in the near future, as specified or directed by
the SO, which shall include the following:
1.4.3
(a)
Joint filler
(b)
Joint sealant
(c)
Sealant backer rod
Warranty
Warrant all designed joints for a minimum period of 10 years, in accordance with contract conditions
against all defects from the date of completion.
[Note 1: This may be defined as a life to first maintenance. Ensure that there are no overriding
requirements in the Client’s form of appointment. It is essential to be clear as to what the warranty is
expected to cover. This will usually be the cost of repair/replacement of defective materials or
workmanship, but not any consequential costs associated with the Works.]
1.4.4
Maintenance Manual
Prepare and submit a maintenance/replacement manual covering the designed joints and materials for
the project. Refer to the Section G01-010:Clause:1.4.5.
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1.4.5
Quality Control Plan
Submit and work to a quality control plan as agreed with the SO. Refer to Section Section G01010:Clause:1.4.7 for details.
2
PERFORMANCE REQUIREMENTS
2.1
Contractor’s Proposal
When carrying out the proposals as set out in Section C03-040:Clause:1.4.1, take account of the
design intent and matters that need consideration as recommended in BS 6093 and the following
requirements in this Section, and provide manufacture data to confirm suitability.
2.1.1
Characteristics of the Joints
Satisfy the required characteristics of the joints as detailed on the drawings in terms of joint designation,
type of joint, horizontal and vertical movement, watertightness and fire-rating.
[Note 1: For each type of joint and joint type designation, the characteristic requirements of the joint are
typically as follows:
(a)
Movement: Vertical
(b)
Movement: Horizontal
(c)
Watertightness, where applicable
(d)
Fire rating
Note 2: Joint Type:
Examples include expansion joint, settlement joint etc.
Note 3: Examples of specified values of characteristics requirements are 15 mm movement,
one hour fire rating, etc.]
2.1.2
Durability
Warrant that the joints shall have a design life of 10 years.
[Note 1: The joints may be specified with a design life shorter than that of the building. Ensure the
maintenance/replacement manual specifies and provides for the replacement of the joint materials
upon the expiry of the specified design life.]
2.1.3
Proprietary Products
When a proprietary product is specified, verify and submit evidence for SOs acceptance that the
product satisfies the performance requirements as stated in this Section. In the event that the desired
performance of the selected product cannot be verified, notify the SO and propose alternative product
for acceptance.
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3
MATERIALS
3.1
Movement Joint System and Fillers
Propose suitable products for the SOs acceptance, giving details on the product information, type and
model, performance requirements and product manufacturer.
Refer to the properties of joint fillers and movement joints in BS 6093.
Provide the proprietary product or approved equivalent for the movement joint system and filler as
specified, scheduled or as indicated in the drawings.
3.2
Joint Waterproofing Material
Propose suitable product to SOs acceptance, giving details on the product information, type and model,
performance requirements and product manufacturer.
Provide the proprietary product or approved equivalent for joint waterproofing materials as specified,
scheduled or as indicated in the drawings for the following:
3.2.1
(a)
Waterstops
(b)
Sealants
(c)
Gaskets
(d)
Baffles
(e)
Primer
(f)
Preformed sealing strips
Water stops
Refer to Section C03-050:Clause:3.5.
3.2.2
Sealants, Gaskets and Baffles
For general requirement refer to Section C03-050:Clause:3.8.
Refer to BS EN ISO 11600 on a systematic performance classification scheme for sealants that are
used in building and construction applications.
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3.2.3
Primer
Apply primer on concrete surfaces to facilitate the application of sealant.
Primer used shall be sealant manufacturer’s recommendation and compatible with the proposed
sealant.
[Note 1: Adhesion of sealants can be a problem, particularly in wet or damp conditions, and therefore
good preparation of joint surfaces is essential. The use of primers is recommended.]
3.2.4
Preformed Compressible Sealing Strips
For general requirements, refer to Section C03-050:Clause:3.8.3.
3.3
Dowel System
3.3.1
Sliding Dowel System
Propose suitable product to the SO for acceptance, giving details on the product information and
model, performance requirements and product manufacturer.
Provide the proprietary product or approved equivalent for the sliding dowel system as specified,
scheduled or as indicated in the drawings.
3.3.2
Tie Bars
Tie bars shall be grade 250, and shall be clean and free from loose mill scale, loose rust, oil and other
deleterious substances.
3.3.3
Mesh Tie Strips
Mesh tie strips shall comply with SS 561, and shall be clean and free from loose mill scale, loose rust, oil
and other deleterious substances.
3.3.4
Dowel Bars
Dowel bars shall comply with SS 560, and shall be provided in straight, sawn (not sheared) ends.
3.3.5
De-bonding
Propose a proprietary de-bonding compound or plastic sleeve for SOs acceptance. Apply to half of the
dowel bars.
3.3.6
Cap
Propose suitable product for SOs acceptance. Fit with not less than 20 mm of compressible material to the
de-bonded end of the dowel.
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3.4
Sheet Membrane for Sliding Joints
Propose a suitable product to SOs acceptance, giving details on the product information and model,
performance requirements and product manufacturer.
Provide the proprietary product or approved equivalent for the sheet membrane for sliding joints as
specified, scheduled or as indicated in the drawings.
[Note 1: The requirements for the membrane are in terms of a high resistance to lateral deformation and
a low coefficient of friction. Layers of heavy grade, or other similar polythene sheets have been used for
this purpose.]
3.5
Crack inducers
3.5.1
Bottom of Slab Crack Inducer
Propose a suitable product to SOs acceptance, giving details on the product information and model,
performance requirements and product manufacturer.
Provide the proprietary product or approved equivalent for the bottom of slab crack inducer as specified,
scheduled or as indicated in the drawings.
[Note 1: Examples include preservative-treated softwood or plastic, triangular section with 50 mm height
or proprietary type. Specify these in thick slabs to reduce the depth of the insert or surface groove.
Note 2: The Concrete Society Technical Report TR 34 does not recommend the use of bottom of slab
crack inducers where crack inducing surface grooves are formed by cutting. There is a risk of misplaced
cracking occurring when the surface cut groove is not properly aligned with the bottom inducer or when
cutting is delayed for too long.
The depth of the insert should be at least one quarter of the depth of the slab. Insert
proprietary type, or provide for example:
3.5.2
(a)
Plastics with detachable top section, to approval; 75 mm deep.
(b)
Stainless steel strip, 3 mm x 50 mm deep.]
Inserted Crack Inducer
Propose a suitable product to SOs acceptance, giving details on the product information and model,
performance requirements and product manufacturer.
Provide the proprietary product or approved equivalent for inserted cracker inducer as specified, scheduled
or as indicated in the drawings.
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3.5.3
Crack Inducing Grooves
Refer to the drawings for the required dimensions of the crack inducing grooves, if any.
[Note 1: Except at expansion and isolation joints, the movement at joints on a floor is generally very
small and the usual rules for the dimensions of sealing grooves may be relaxed. This enables thin joints
to be formed by sawing, and these fine joints are more durable under the passage of wheel loads. A
sawn groove will be about 6 mm wide, but wider grooves can be cut if required. The depth of the grooves
should be at least one quarter of the depth of the slab. Insert required depth and width for example:
(a)
Depth: 50 mm.
(b)
Width: as narrow as possible.]
4
WORKMANSHIP
4.1
Forming Joints
4.1.1
Accuracy
Position and form joints accurately, straight, well-aligned and truly vertical or horizontal or parallel with
setting out lines of the building. Construct the joint within an acceptable tolerance of 2 mm unless
otherwise specified.
4.1.2
Pour Sequence
Plan the pour sequence in such manner as to minimise restraints.
Do not use a chequered board sequence for water-resisting construction.
For elements cast monolithically that include wall and floor slabs, align joints as far as practically possible,
to minimise cracking.
[Note 1: Special considerations apply to ground slabs such as those used in warehouse
construction, e.g. refer to The Concrete Society Technical Report TR 34 and the current edition of
Deacon, RC’s Concrete ground floors: their design, construction and finish.
Note 2: Where the casting of members is long in length, it can be helpful to leave short gaps to be
infilled subsequently; for maximum effect, they should be left open for at least 3 months, but given the
possible constraints this would impose, an alternative is to give more detailed consideration to where
shrinkage is likely to occur and its effect on the structure, and take into account that about half the total
shrinkage will occur within about 28 days.]
4.1.3
Modifications
Modifications to any joint design or location, if necessary, shall be agreed on before proceeding.
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4.1.4
Placing Concrete
Prevent concrete entering joints or penetrating compressible joint fillers resulting in making movement
joints ineffective.
Do not place concrete simultaneously on both sides of movement joints.
4.2
Workmanship for Construction Joints
Propose suitable joint location and detail for SOs acceptance. Take note of any desired location
indicated in the drawings.
Construction joints shall be formed wherever there is a discontinuity in placing concrete in elements of
concrete structures. A water stop, which shall be either a hydrophilic expansion strip or a water bar
embedded in the structure, shall be incorporated in all construction joints in elements which form the
external hull of underground structures, retaining walls and where otherwise specified in the drawings.
Spacing of construction joints shall be in accordance with good concreting practice and adequate
precautions shall be taken against shrinkage cracking. Concreting shall be carried out continuously. The
joints shall be at right angles to the general direction of the member and shall take due account of
shear and other stresses.
Concrete shall not be allowed to run to a featheredge and vertical joints shall be formed against a stop
board. The top surface of a layer of concrete shall be level and reasonably flat unless design
considerations make this undesirable. Joint lines shall be so arranged that they coincide with features
of the finished work, wherever possible.
If a kicker (i.e. a starter stub) is used, it shall be at least 70 mm high and carefully constructed.
Prior to re-commencement of concreting on a joint, the surface of the concrete against which new
concrete will be cast shall be free from laitance and shall be roughened. Take care to ensure that the
joint surface is clean and thoroughly wetted immediately before the fresh concrete is placed against
it.
For general requirements refer to Section C03-050:Clause:4.14.
[Note 1: Although construction joint positions can often be agreed upon orally for a simple and
straightforward project, it is definitely desirable, if joints are not shown in the drawings, to agree on joint
positions and have them recorded in advance. A marked-up print will suffice. In slabs and beams, it is
a general rule to place construction joints in areas of low vertical shear and flexural stresses although
where this is impossible, the joint must be detailed to provide shear resistance, e.g. a rebate should be
formed in a wall to receive a slab that spans into it. In other cases, joints can be stepped or sloped.]
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4.3
Workmanship for Expansion, Contraction and Other Movement Joints
Expansion, contraction and other movement joints shall be incorporated in the Works as shown on the
drawings or as directed by the SO.
Polyethylene or similar material shall be used for expansion joint fillers and not fibre boards or bitumen
impregnated material. Filler material shall be stored flat on a dry surface adequately protected from rain
or moisture. Filler material that has been damaged or has started to deteriorate shall not be
incorporated in the Works.
The joint shall be sealed by an accepted sealer applied in strict accordance with the manufacturer's
instructions to the dimensions shown on the drawings. The surface of the concrete to which the sealer is
to adhere shall be straight and cleaned of all filler material, dirt, oil, grease and other matter. The
sealer shall be applied by methods recommended by the manufacturer so that the sealer is brought
flush to the surface of structure and a smooth surface is achieved. Excess material and spillage shall
be properly cleaned off and removed.
Dowel bars shall be installed and cast in across the movement joint where shown in the drawings.
The bars shall be straight with clean cut ends of the diameters and lengths as shown in the drawings or
in the schedules.
The bars shall be firmly supported in the positions shown in the drawings so that they are not displaced
during the casting of the concrete in the first part of the structure. After the concrete has hardened and
the formwork removed, the projecting ends shall be cleaned of all concrete spillage and painted with 2
coats of an accepted bituminous paint and caps shall be fitted to the free ends of the bars.
The projecting ends of dowel bars are required to be protected from bending or other damage prior to
concreting the succeeding bay. The bituminous paint shall be applied as soon as practicable, but end
caps shall not be fitted until immediately prior to the succeeding concreting operations.
4.4
Workmanship for Joint Waterproofing
For general requirements, refer to Section C03-050:Clause:4.14.
4.4.1
Connection with Diaphragm wall
All leaks in the diaphragm walls and connections shall be sealed.
At the junctions with the base slab and roof slab, horizontal continuous runs of re-injectable grout tubes
within the slab sections shall be installed on properly prepared surfaces to the satisfaction of the SO.
After completion of the base slab and roof slab, regardless whether there is any leak, the junction
with the base slab and roof slab shall be grout injected.
4.4.2
Sealants
Apply in accordance manufacturer’s recommendation or as agreed by the SO. Avoid overspill onto the
adjacent concrete surface.
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4.5
Crack-inducing Grooves
Insert temporary strips into the fully compacted concrete. Compact and level the slab along the strips.
Remove strips.
If the type of aggregate so permits, saw grooves in the top surface of the slab sufficiently early (within 24
hours of casting slab) to prevent random cracking.
[Note 1: Narrow crack inducing grooves in floor slabs may not need to be sealed, e.g. in industrial
premises where conditions are dry. However, in wet conditions, and where there are hygienic or dust
control requirements, sealing will be necessary. The lower part of the groove may be filled with
preformed foamed plastics strip to reduce sealing costs. The use of a "gun grade" material will be
found more convenient with narrow grooves, as hot-poured sealants tend to overflow and spread across
the adjacent floor surface. Two-stage compressible sealing strip systems are an alternative.]
[Note 2: When construction takes place under a completed roof, grooves may be cut up to 7 days after
casting. When construction is in the open in hot and sunny weather, the grooves must be cut within 24
hours. This Clause is based on the view that to reduce the possibility of random cracking, the grooves
are best cut within 24 hours. In any case, there is little advantage in delaying the operation. Early
sawing may be precluded by concrete mixes containing the following:
4.6
(a)
Very hard aggregates, e.g. quartzite or flint
(b)
High proportions of cement replacement materials - ground granulated blast-furnace slag (GGBS) or
pulverized fuel ash (PFA)]
Bottom of Slab Crack Inducers
Fix bottom of slab crack inducers securely to sub-base.
4.7
Inserted Strip Crack Inducers
4.7.1
Forming groove
Fully compact and level the concrete, insert steel T bar and withdraw to form void.
4.7.2
Placing strip
Carefully insert strip to accurate line and level, then re-compact and re-level slab.
4.8
Control of Jointing on Site
Control of jointing on site is essential and is required to take account of critical factors, particularly
where specifically identified or directed by the SO, including the following:
(a)
Joint clearances are maintained within specified limits;
(b)
Continuity of seals is maintained.
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4.9
(c)
Operations which are difficult (such as forming and sealing of cloaks and cavity trays) are correctly and
properly executed.
(d)
The correct assembly sequence is followed.
(e)
Work to be hidden by subsequent work is inspected before being covered;
(f)
Features which are difficult and costly to rectify are checked.
Preparation for Jointing
The component surfaces shall be properly prepared to receive jointing materials. Contaminants,
including dust, loose particles, moisture, oils and greases, and corrosive materials are required to be
cleaned from the joint faces before application of primers and sealants. Rough surfaces shall be
ground flat before installation of gaskets. Temporary protective coating meant for the delivery of
components to site shall be properly removed before the application of the sealant or gasket.
4.10
Application and insertion of jointing products
Follow the manufacturer’s recommendations on the application of products. The sequence of building
operations shall be such that ready access by the operator to the joints is ensured and that interaction
with other trades is avoided.
4.11
Safety in application of jointing products
Refer to the manufacturer’s literature and recommendations on the use of products and the
precautions to be taken in dealing with hazardous materials, including sealants and primers that contain
flammable solvents or toxic constituents, which may cause dermatitis and nausea in certain individuals.
In particular, care is needed in the safe disposal of hazardous waste and containers in accordance with
statutory requirements.
Assess risks arising from hazardous substances at work and determine the measures needed to prevent
or adequately control exposure to them. Propose for the SOs acceptance all necessary measures to
eliminate the hazardous substance by changing the process or substituting with a safe or safer
substance. Where this is not reasonably practicable, propose for SOs acceptance, control measures of
the exposure, including the use of enclosure, ventilation equipment, general ventilation, safe systems of
work and handling procedures. Other measures shall include personal protective equipment to control
exposure.
5
VERIFICATION AND SUBMISSIONS
5.1
Submission
5.1.1
Tender Submission
Submit the following information with the tender:
(a)
Technical details, including catalogues of the joint system
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5.1.2
(b)
Certificates to show compliance with the codes set out in the specifications
(c)
Sample of typical joint materials
(d)
Records of past projects where the proposed joint system has been successfully installed
Method Statement
Provide a method statement for the acceptance of the SO prior to commencement of the Works containing
at least the information given below:
5.1.2.1
Materials
For each material or system proposed, manufacturersâ data, test results, design life certificates, health
and safety information.
5.1.2.2
Sequence
Proposed sequence for each of the operations required to complete the works.
5.1.2.3
Methods
All tools and equipment to be used, application methods, proposed methods for undertaking the various
elements of the Works, including details of access and indicating how any restrictions on noise and
nuisance shall be met.
5.1.2.4
Site Organisation and Quality Control
Provide details of how the Works shall be controlled, sampling regimes, proposed testing methods and
organisation.
5.1.2.5
Project Reference
Contractor shall submit the project references where the materials have been used previously with
satisfactory performances.
5.1.3
Product Certificates
For all materials proposed, submit certificates from manufacturers showing evidence of compliance with
the specified quality requirements.
5.1.4
Maintenance / Replacement Manual
Cover all joint systems and materials in the maintenance manual to be submitted before handing over.
Propose and submit for the SOs acceptance on the details and requirements to be in the building
maintenance manuals which shall provide as appropriate:
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(a)
An inspection frequency and schedule
(b)
An expected replacement schedule for jointing products
(c)
An identification of joints where lack of maintenance would lead to significant consequential damage
(d)
Guidance on how to maintain joints (including any special precautions needed to avoid inappropriate
repairs)
(e)
Means to identify products or types of jointing products used
[Note 1: Generally, joints may be inspected at intervals equivalent to 1/5 of life expectation and
additionally, after the first year in service, all joints subject to movement should be inspected for signs of
premature failure.]
5.1.5
Warranty
Submit the warranty for SOs acceptance upon completion of the works.
5.2
Samples/Mock-ups
Submit samples of all joint systems and materials for SOs acceptance prior to ordering of the material.
Identify and label the samples appropriately.
5.3
Tests
5.3.1
Watertightness
For joints specified as watertight, test all joints after installation with a spraying hose for water tightness.
If there is any leakage, dampness and presence of seepage water, propose and carry out rectification or
replacement to the SOs acceptance.
5.3.2
Fire Resistance
For joints specified with fire rating requirements, submit certificate or evidence demonstrating compliance
with SCDF requirements. If certificate is not available, submit samples of the materials to SCDF for
testing to obtain the certification.
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(15) C03-050 Water-resistance to Concrete Structures
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1
GENERAL
Read this Section with G01-010 "General Requirements" and all other contract documents.
1.1
Scope
This Section covers primarily the requirements of waterproofing for below ground in-situ concrete
structures to exclude water. It may be adapted to cover the concrete element of water retaining
structures, e.g. tanks and swimming pools. For waterproofing applied as surface finish to such
structures, refer to Architectural specifications.
1.2
Not In Use
S1.2
Related Sections
Read this Section in conjunction with the relevant requirements of the following section:
C03-010
Concrete Construction Generally
C03-040
Designed Joints
1.3
Standards, Codes, Regulations and Technical References
1.3.1
Standards and Codes
Unless otherwise agreed by the SO, ensure all of the Works comply with the relevant requirements of
the standards and codes listed below or referenced in the body of the Specification. Alternative
Standards and Codes may be proposed for approval by the SO, provided it can be demonstrated that
the alternative standards and codes comply with the requirements of the standards specified. All
standards and codes quoted are the current version, unless specific year references are noted.
In the event that the standards or codes are revised or superseded, refer to the current edition or the
appropriate substitution for the relevant subjects.
Singapore Standards
SS EN 1992-1-1
Design of concrete structures - Part 1-1 General rules and rules for
buildings
SS EN 1992-3
Design of concrete structures - Part 3: Liquid retaining and
containment structures
SS EN 13791
Assessment of in-situ compressive strength in structures and
precast concrete components
SS EN 206
Concrete- Specification performance, production and conformity
SS 544-1
Concrete - Complementary Singapore Standard to SS EN 206 Part
1: Method of specifying and guidance for the specifier
SS 544-2
Concrete - Complementary Singapore Standard to SS EN 206 Part
2: Specification for constituent materials and concrete
SS 637
Code of practice for waterproofing of reinforced concrete buildings
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SS 374
Preformed waterproofing membranes for concealed roof
Other Standards
1.3.2
BS EN 12390-8
Testing hardened concrete - Depth of penetration of water under
pressure
BSEN 13670
Execution of concrete structures
BS EN 14188-3
Joint fillers and sealants - Specification for preformed joint seals
BS EN ISO 527-1
Plastics. Determination of tensile properties - Part 1: General
principles
BS EN ISO 527-2
Plastics. Determination of tensile properties - Part 2: Test
conditions for moulding and extrusion plastics
BS ISO 16938
Buildings and civil engineering works - Determination of the
staining of porous substrates by sealants used in joints.
BS 1881-122
Testing concrete - Part 122: Method for determination of water
absorption
BS 6093
Design of joints and jointing in building construction - Guide
BS 6213
Selection of construction sealants - Guide
BS 8000-16
Workmanship on construction sites - Part 16: Code of practice for
sealing joints in buildings using sealants
BS 8102
Code of practice for protection of structures against water from the
ground
DIN EN ISO 2286
Rubber- or plastics-coated fabrics - Determination of roll
characteristics - Part 3: Method for determination of thickness
ISO 11600
Building construction - Jointing products - Classification and
requirements for sealants
ASTM D638
Standard test method for tensile properties of plastics
ASTM D5385
Standard test method for hydrostatic pressure resistance of
waterproofing membranes
ASTM E96-00e1
Standard test methods for water vapour transmission of materials
ASTM E154-99
Standard test methods for water vapour retarders used in contact with
earth under concrete slabs, on walls, or as ground cover
Technical References
Refer to the following technical references for guidance in carrying out the Works:
1.4
(a)
BCA publication, Good Industry Practices - Waterproofing for Internal Wet Areas
(b)
BCA publication, on Good Industry Practices - Waterproofing for External Wall
(c)
CIRIA Report 139 Water-resisting basements
(d)
CIRIA 766 Control of cracking caused by restrained deformation in concrete
(e)
CD 358 Waterproofing and surfacing of concrete deck (Appendix B: Procedures for certification of
waterproofing systems on concrete bridge decks)
Trade Preamble
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1.4.1
Contractor’s Submissions and Proposals
Engage qualified and experienced personnel to develop the design and propose for the SOs acceptance a
complete waterproofing system to comply with the performance and quality requirements as set out in
this specification.
1.4.2
Co-ordination with Other Works
Co-ordinate all relevant interfacing work packages and trades as follows:
1.4.3
(a)
Structural substrate works
(b)
Services work crossing or penetrating the waterproofing works
Warranty
Provide a warranty for a period of 10 years in accordance with contract conditions for the entire
waterproofing system, including all components and accessories.
The waterproofing warranty shall cover the water tightness of the underground structures for the
waterproofing systems and shall be given jointly and severally by the Contractor, manufacturer, supplier
and applicator.
[Note 1: Some practices use a warranty period of 15 years.
Note 2: The warranty must be specific for the task at hand and several warranties may be required
depending on the nature of the protection and system required by the project.]
1.4.4
Maintenance Manual
Prepare and submit for the SOs acceptance a maintenance/replacement manual for the waterproofing
system, including the joint fillers, re-injectable grout tubes and sealants, to be carried out by the building
owners. Refer to Section G01-010:Clause:1.4.5 for details.
1.4.5
Quality Control Plan
Submit and work to a quality control plan as agreed with the SO. Refer to the Section G01010:Clause:1.4.7.
1.4.6
Specialist Personnel
Propose for the SOs acceptance competent and suitably experienced waterproofing specialist personnel,
including operatives and applicators, and material suppliers to meet the specified performance
requirements of all aspects of the waterproofing works. The waterproofing works shall be executed by
suitably experienced operatives or applicators who have met the skills criteria using the products on
other similar works and under similar conditions.
[Note 1: In some cases, the Work may be carried out as part of the general substructure concrete.
There may be a specialist who will be responsible for the supply of the products which may be installed
by others.]
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2
PERFORMANCE REQUIREMENTS
2.1
Design Input Requirements
Account for the following design input requirements when carrying out the proposals in Section C03050:Clause:1.4.1 and refer to the BCA publication "Good Industry Practices - Waterproofing for
Internal Wet Areas".
2.1.1
Durability
Unless otherwise agreed by the SO, the waterproofing system is required to achieve a minimum design
working life of 10 years, the assumed period for which the waterproofing system is to be used for its
intended purpose with anticipated maintenance but without major repair being necessary.
[ Note 1: In some projects, a minimum design working life of 15 years is used for the waterproofing
system.]
[Note 2: The working life under this sub clause may be different from the concrete working life.]
2.1.2
Basement Grade
Unless otherwise specified in the drawings or directed by the SO, use grades of internal environment,
with regard to basement usage and performance level, as defined in BS 8102, taking into consideration
of the functional environmental requirements, groundwater conditions, risk assessment and options for
drainage outside the structure.
Propose for the SOs acceptance on the grade of performance level required for the dryness of buildings as
defined in BS 8102.
[ Note 1: CIRIA 139 provides guidance on levels of dryness which relate to habitable use and archive
storage.]
[ Note 2: The performance level for the dryness of buildings may be quantified further as appropriate,
for the selection and delivery of the appropriate basement environment and that it requires consideration
of anticipated ground water levels, level of ventilation provided, the sub- slab drainage and external
drainage generally, and a risk analysis and assessment.
Note 3: For all grades, where reliance is being placed on the concrete to provide the water resistance
to the structure, there is a need to place particular emphasis on achieving the correct mix design and
ensuring high standards of workmanship.]
2.1.3
Material Performance
2.1.3.1
Material Quality
Ensure that all materials comply with the relevant product standards as defined in this specification.
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2.1.3.2
Hydrostatic Head Resistance
All materials used for waterproofing the structure are to be capable of resisting the hydrostatic head
associated with the relevant site conditions.
3
MATERIALS
3.1
Materials Compatibility
Ensure that all materials used are compatible and comply with the manufacturer’s recommendations.
3.2
Damp-proof Membranes
Suitable materials for damp-proof membranes include the following:
(a)
Heavy-duty polyethylene sheets
(b)
Bituminous sheets
(c)
Bituminous felt
Minimum thickness of the damp-proof membranes to be used for different types of ground conditions
shall be in accordance with SS 637. The sheeting shall be laid and jointed in accordance with the
manufacturer’s written instructions, lapped 150 mm at joints and taped with a waterproof tape, laid over
lean concrete.
[Note 1: This is a standard requirement for conventional ground slab construction to stop ground water or
vapour rising; it will not in itself be appropriate or effective in situations where there is a very high water
table and the structure is, or is likely to be, subject to water pressure or ingress.]
3.3
Tanking Membranes
Use preformed membranes or liquid-applied membranes.
3.3.1
Preformed Bonded Membranes
3.3.1.1
Suitable Materials
Suitable materials for bonded membranes include the following:
(a)
Not In Use
S(a)
Flexible and self-adhesive bituminous-based membrane with a minimum thickness of
1.5 mm, based on high performance 250 micron thick polymer films.
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(b)
Flexible membrane capable of forming a full bond with concrete subsequently cast, with a minimum
thickness of 1.5 mm.
The membrane shall form a continuous and permanent mechanical bond to poured concrete to prevent
lateral water migration between the membrane and structural concrete.
Do not use bentonite-based membranes.
[Note 1: Do not use bentonite-based membranes unless the intent is to provide a hydrophilic solution as of
a multi-tiered protection system and subject to SOs approval.]
Membranes shall be robust for the intended application and purpose without tearing or separating
during the placement and application process. Membranes shall be tested prior to acceptance by test
methods, acceptance parameters and rectification methods agreed to by the SO.
3.3.1.2
Physical Properties
Required physical properties of bonded membranes are as follows in Table 1: Table 1.
Physical properties of bonded membranes
Performance parameter
Thickness
Typical value
Test method
1.5mm min.
DIN EN ISO2286-3
50m to 70m
ASTM D5385
DIN16726
Water vapour transmission rate
0.06g/m²/day
ASTM E96
Tensile strength (carrier film)
Longitudinal 48.4 N/mm²
Transverse 45.4 N/mm²
SS 374
Puncture resistance
280N
ASTM E154
Hydrostatic head resistance
3.3.2
Liquid-Applied Membranes
3.3.2.1
Components
Provide a system comprising a primer and one or more layers of a two-component liquid-applied
elastomeric membrane.
[Note 1: Liquid applied waterproofing systems are fully bonded to the substrate and thus should resist
water tracking under them if water penetrates. Dynamic crack accommodation is normally by elastic
deformation of the membrane. However, some systems, less commonly used, are reinforced with
glass fabric - these accommodate dynamic cracks by a combination of local debonding and elastic
deformation. Reinforced membranes typically have a higher tensile strength but are less elastic than
unreinforced systems.]
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3.3.2.2
Properties
Required properties of liquid-applied membranes are as follows in Table 2:
Table 2. Properties of liquid applied membranes
Performance
Typical value
Test method
Total dry film thickness
Minimum 2.5 mm
.
Tensile strength
unaged
180 days heat aged at 70°C
28 days water soaked at 23°C
500 hr UV aged
8.6
10.6
9.1
8.8
BS EN ISO 527-1 and 527-2
Elongation to failure (%)
unaged
180 days heat aged at 70°C
28 days water soaked at 23°C
500 hr UV aged
117
124
122
123
BS EN ISO 527-1 and 527-2
Refer to BS EN ISO 527 for determining the tensile properties of plastics and plastic composites under
defined conditions.
Refer to CD 358, Appendix B which gives a series of procedures for the certification of waterproofing
systems for concrete bridge decks.
3.3.3
Primer
For bitumen-based membranes, use a bituminous primer in accordance with the manufacturer’s
recommendations. Concrete surface shall be prepared to U3 finish, prior to the application of a
bituminous primer coat.
3.4
Waterproofing Admixtures (Hydrophobic & Hydrophilic)
Where the required waterproofing performance is to be achieved by the use of concrete admixture
systems, provide full details of the proposed admixtures and mixes to the supplier and the final design
mix to the SO for agreement and approval.
The waterproofing admixtures shall make the concrete impermeable to water and hydrophobic with
pore-blocking content as its primary function. Provide at least 15 years of a successful track record of the
products in the same manner used for the regional demarcation of waterproofing for concrete. The
required characteristics are as follows in Table 3:
Table 3. Required characteristics for admixtures
Performance
Typical value
Test method
Water absorption at 7 days
Not more than 1%
BS 1881: Part 122
Water permeability coefficient under 5.0kg/cm2
not greater than
10-13 m/s
DIN 1048
Average penetration depth
Pore-blocking content determination
not greater than 15 mm
>0.025% (by weight)
BS EN 12390-8
ASTM D5368 (Method C) choose
chloroform as extracted solvent.
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3.5
Waterstops
All waterstops shall be capable of providing hydrostatic resistance appropriate to the structure and joint
in which installation is provided.
3.5.1
Active Waterstops
Expansive hydrophilic waterstops shall have a volumetric increase of between 200% and 300% when in
contact with water.
Do not use bentonite-based hydrophilic waterstops unless with approval of the SO.
Hydrophilic waterstops shall be provided with a delay coating that retards the onset of expansion to
prevent premature expansion prior to concrete casting.
The hydrophilic waterstops shall exhibit good consistency in measured swell rate during the repetitive
wetting and drying cycle.
3.5.2
Passive Waterstops
Use flexible rubber or PVC for passive waterstops.
3.6
Injection System
Provide a complete applicator system, including hoses, junction boxes, resin, pumps and all other
components required for its installation and use as provided by the manufacturer or as directed by the
SO. The injectable tube system shall be suitable for resinous or cementitious grout.
3.6.1
Resin
Use flexible aqua-reactive injection resin which is chemically resistant and produces an expanded
closed-cell foam on contact with water.
Provide details of the proposed product to the SO for agreement prior to starting work.
3.6.2
Hoses
Hoses shall be tough, re-injectable, flexible and chemically inert, and capable of not being choked
by the hardened grout from previous injection cycles.
3.6.3
Junction Boxes
Junction boxes shall be installed in locations which are readily accessible.
3.6.4
As-built Manual
Upon completion of the Works, submit a manual containing detailed instructions for grouting and flushing,
material data, as-built record drawings showing location of all tubes and their respective junction boxes,
and other information relevant to future maintenance.
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3.7
Chemical/Cement Grout or Gel
Use approved chemical grout, which shall form a continuous, uniform gel. Mix proportions shall be as
recommended by the manufacturer.
3.8
Materials for Joints
Unless otherwise agreed by the SO, the classification and requirements for sealing joints to meet
anticipated movement in service shall follow ISO 11600.
3.8.1
Waterbar systems for Joints
Joints are required to have adequate width to accommodate anticipated movements and to ensure
the jointing waterbar performs within its required capabilities. The gap of the joints must be sealed for
watertightness.
Waterbars are used in conjunction with surface sealants and hydrophilic waterstops as a multi- tier
system against liquid ingress under high static or dynamic pressures.
[Note 1: Refer to BS 6213 for more details.]
3.8.1.1
Waterbar system for use within a wet environment
Where there is permanent contact with water, waterbars are from approved polyurethane or polysulphide
compounds.
3.8.1.2
Waterbars for use under traffic loads
Use high modulii dynamic systems under traffic loading conditions.
[Note 1: Refer to CD 358 on Waterproofing and surfacing of concrete bridge decks which gives a
series of procedures for the certification of waterproofing systems for concrete bridge decks.]
3.8.2
Gaskets
Use natural rubber compounds protected by a synthetic rubber skin. If special properties, such as
resistance to oils, are desired, synthetic rubber and plastics materials have to be specifically formulated
for the intended use. Gaskets can be solid or hollow sections of various profiles formed from cellular or
non-cellular material or combinations of these materials or sections.
3.8.3
Sealing Strips
Submit for the SOs acceptance on the types of sealing strips which are mastic strips and impregnated or
coated cellular strips to be used.
3.8.4
Joint fillers
Use joint fillers that meet the requirements of BS EN 14188.
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3.8.5
Baffles
Comply with BS 6093.
3.9
Waterproof Renders
Where required, propose for the SOs acceptance proprietary products, organic or inorganic, which modify
the permeability of the concrete for waterproof renders.
[Note 1: These may be used in conjunction with âwaterproof concreteâ or structurally integral protection
without any admixtures to improve the vapour resistance of the structure. It is not recommended for use as
a primary form of waterproofing.]
3.10
Formwork Ties
Propose for the SOs acceptance, a type of formwork ties capable of maintaining the water resistance
of the structure. To prevent future water migration through tie form voids for the case of using
removable tie form, cast in galvanised formwork ties that shall be approved by the SO for use with the
external wall. The 2 ends of a tie shall be infilled with suitable non-shrink grout mixed with hydrophobic
type waterproofing additive.
4
WORKMANSHIP
4.1
Construction Loads
Ensure during construction that the structure is not subjected to loads that will cause distress to the
concrete and the waterproofing system.
4.2
Storage
Keep all materials clean and dry, avoid damage and use strictly in accordance with the manufacturer’s
recommendations.
4.3
Protection
Apply protection to materials in accordance with the accepted proposals given in the method statement.
4.4
Pour Sizes
Control pour sizes to optimise work practice. Refer to Section C03-010:Clause:4.5.1.
[Note 1: Pour size is independent of crack width or spacing if reinforcement is continuous. Refer to SS
EN 1992-3.]
[Note 2: Restrictions on pour size will depend, amongst other considerations, on the
demonstrated ability and track record of the contractor and on a risk assessment for the structure;
the consequences of water ingress can vary for different structures and requirements.]
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4.5
Fixing Formwork
Do not use methods of fixing formwork which result in holes through the concrete section when the
formwork is removed.
4.6
Pipe Penetrations
Use a puddle flange or other appropriate sealing detail. Avoid post-formed openings. [Note 1: It
is much harder to ensure an effective seal around a post-fixed item.]
4.7
Temporary Propping
Allow adequate area around any temporary penetrations to incorporate waterstops and to ensure full
compaction of concrete. Submit in advance to the SO for his acceptance the details and method
statements required for construction.
4.8
Inspection
Carry out inspection jointly with the SO before backfilling or covering up to identify defects which may lead
to water penetration. Perform further joint inspection to identify any water penetration after backfilling and
when any groundwater has returned to normal level.
4.9
Repairs
Where concrete shows signs of liquid penetration, through leakage or damp patches, submit proposals
for rectification, including details of proposed materials and methods of application, to the SO that comply
with BS 8102, Clause 8.8 and 8.9.
Ensure that all repair materials are compatible with materials used in the original construction.
[Note 1: Standard methods are injection of resin material, breaking out and recasting or internal
rendering. In some instances, the latter may not be acceptable. It is necessary to consider the
required finish and the specified performance in evaluating proposals, including the consideration of reestablishment of ground water level resulting in a greater possibility of leaks appearing.]
4.10
Waterstops
Use waterstops in all construction and movement joints in concrete specified as water resistant unless
otherwise noted and agreed with the SO.
Obtain the agreement of the SO for the methods to be used to maintain the waterstops in position
and to avoid damage during concreting and formwork removal.
[Note 1: This is a reasonable starting point for specifying. It is important to be aware, however, that
waterstops can themselves provide an entry route for water if they are not correctly fixed. With good
workmanship, it is still necessary in construction joints. The need for movement joints in substructures
should be assessed carefully - if not needed, their omission is advantageous in removing one possible
entry point for water.]
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4.10.1
Internal Waterstops or Waterbars
Submit details to the SO for acceptance of the methods to be used to ensure full compaction around the
waterstop or waterbar.
[Note 1: The location of a waterstop or waterbar may itself provide a passage for water if the material is
incorrectly fixed and/or the concrete does not form a continuous dense surround.]
4.10.2
Hydrophilic Waterstops
Locate in a smooth groove formed in the kicker or at the edge of a slab.
[Note 1: Hydrophilic waterstops are generally preferred in situations where there are permanently
wet conditions.]
4.11
Bonded Membrane Systems
4.11.1
Finishes
The finishes shall meet the membrane manufacturer’s requirements. In general, provide the following
minimum conditions:
4.11.2
(a)
Prepare slabs to receive a waterproof membrane to at least a "Plain Finish" as defined in BS EN 13670.
(b)
For vertical surfaces provide at an "ordinary finish" as defined in BS EN 13670 and where necessary, grind
to remove arrases and fill locally with mortar using a steel trowel to produce a smooth finish.
Application
Lay primer and membrane strictly in accordance with manufacturer’s instructions, including instructions on
length and location of laps.
4.11.3
Change in Concrete Surface
Lay the material across a change in the plane of the concrete surface provided it is sufficiently pliable
to enable the adhesive to remain in contact with the primed concrete. Where this cannot be achieved,
provide preformed angles or other fixtures as required and bond to the concrete surface.
4.11.4
Protection
Provide protection as soon as possible after laying by boards or other material with the agreement of the
SO, in accordance with the membrane manufacturer’s recommendations.
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4.11.5
Continuity
Ensure that there is continuity of waterproofing at all junctions within the structure and provide explicit
details showing how this will be achieved.
4.12
Liquid-applied Membranes
Apply to concrete which has at least gained the required 28 days strength and with a moisture content
less than 5% prior to application, unless otherwise recommended by the manufacturer.
[Note 1: Some systems can be applied to 7-day-old concrete. Confirm with the manufacturer if required.]
4.12.1
Temperature
Generally, apply at a temperature less than 35°C unless otherwise recommended by the manufacturer.
4.13
Pressure Grouting
(a)
Drill grouting holes in carefully selected locations.
(b)
Locate drill holes away from embedded reinforcement by using a magnetic induction digital display type
cover meter. If drill hits reinforcement, stop drilling immediately, relocate hole and inform the SO.
(c)
On completion, make good holes with 1:3 ratio of a damp cement and sharp sand mix, thoroughly rammed
in and finished neat and flush.
4.14
Workmanship for Joints
4.14.1
Sealants for Joints
Prepare the joints and apply the sealants, back-up materials, bond breakers and joint fillers in accordance
with the requirements of BS 6093, BS 6213 and BS 8000.
4.14.2
Gaskets
Apply in accordance with the requirements of BS 6093, BS 6213 and BS 8000.
4.14.3
Sealing Strips
Apply in accordance with the requirements of BS 6093, BS 6213 and BS 8000
Refer to BCA publication on "Good Industry Practices - Waterproofing for External Wall".
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5
VERIFICATION AND SUBMISSIONS
5.1
Submissions
5.1.1
Tender
Submit details of the proposed waterproofing system and supporting documents such as method
statement, material testing results, samples, maintenance procedure during and after the warranty
period, and track record with the tender submission for the SOs review and acceptance.
5.1.2
Method Statement
Submit a detailed method statement describing the waterproofing system to be used, installation details,
manufacturersâ details and requirements and protective measures to be adopted at all stages of the
application.
5.1.3
Suitability of System
Before starting work, provide written confirmation to the SO from the Supplier of the waterproofing
system that the proposed concrete mix, placing methods, release agents, curing compounds, movement
joint details, surface finishes, methods of supporting reinforcement and loads will not adversely affect the
performance of the system.
[Note 1: It is not always easy to obtain the written confirmation described here, and there may be a
number of caveats which make any such statement of less value, but this does provide an opportunity
to ensure that all parties understand what is required and the expected level of performance.]
5.1.4
Shop Drawings
Submit shop drawings to the SO for acceptance showing the positions of joints and details of all materials
to be used. Details shall include schedules of junction pieces and isometric layouts of waterbars.
5.1.5
Details
Submit co-ordinated details for the SOs acceptance, including the following:
(a)
Junctions between roof/base slabs and external walls
(b)
Pipe penetrations through external walls
(c)
Junctions between base slab and piles/king posts
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5.1.6
Product Certificates
For all materials proposed, submit certificate from manufacturers showing evidence of compliance with
the specified quality requirements.
5.1.7
Maintenance/Replacement Manual
Cover all waterproofing systems used and materials specified in the maintenance manual to be submitted
before handing over.
5.1.8
Warranty
Submit the warranty for the SOs acceptance upon completion of the Works.
5.1.9
Quality Control Plan
Prepare and submit a quality control plan for the SOs acceptance prior to commencement. Submit all
quality control records progressively during the course of construction.
5.2
Samples/Mock-ups
Submit samples of the proposed system and materials for the SOs acceptance prior to ordering of
materials. Identify and label all samples appropriately.
5.2.1
Mock-up Panels
Prior to commencement of work, submit proposal on mock-up panels for the SOs acceptance, that shall
be constructed at agreed locations as selected by the SO to test products specified in this Section and
arrive at acceptable methods of installation.
5.3
Inspection and Rectification
Carry out visual inspection to the completed works.
If there is any leakage, dampness and presence of water seepage resulting from hydrostatic pressure
or capillary action on the surfaces of the structural elements that are visible, submit proposals for
rectification for the SOs acceptance and carry out the rectification works.
The rectification works shall achieve the same design working life and performance as specified by the
waterproofing system.
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(16) C03-060 Precast Concrete Works
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1
GENERAL
Read this Section with G01-010 "General Requirements" and all other contract documents.
1.1
Scope
This Section covers requirements for the design, fabrication, handling, storage, transportation and erection of
structural precast concrete elements, including elements used in composite structures.
1.2
Related Sections
Read this Section in conjunction with the relevant requirements of the following sections:
C03-010
Concrete Construction Generally
C03-020
Reinforcement
C03-030
Formwork and Falsework
C03-040
Designed Joints
C03-050
Water-resistance to Concrete Structures
C03-070
Prestressed Concrete Works
C05-010
Structural Steelwork
C05-020
Protective Works for Structural Steelwork
For precast concrete used as cladding, refer also to the architectural specifications.
1.3
Standards, Codes, Regulations and Technical References
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1.3.1
Standards and Codes
Unless otherwise agreed by the SO, ensure all of the Works comply with the relevant requirements of the
standards and codes listed below or referenced in the body of the Specification. Alternative standards and
codes may be proposed for approval by the SO, provided it can be demonstrated that the alternative standards
and codes comply with the requirements of the standards specified. All standards and codes quoted are the
current version, unless specific year references are noted.
In the event that the standards or codes are partially superseded or have become obsolete, refer to the current
edition or the approved substitution for the relevant clauses.
Singapore Standards
1.3.2
SS EN 197-1
Cement: Composition, specification and conformity criteria common
cements
SS EN 206
Concrete: Specification, performance, production and conformity
SS EN 1992-1-1
Eurocode 2 - Part 1-1: General rules and rules for buildings
SS EN 1992-3
Eurocode 2 Part 3: Liquid retaining and containing structures
SS EN 12620
Specification for aggregates for concrete
SS CP 81
Precast concrete slab and wall panels
SS 544-1
Concrete - Complementary Singapore Standard to SS EN 206 - Part
1: Method of specifying and guidance for the specifier
SS 544-2
Concrete - Complementary Singapore Standard to SS EN 206 - Part
2: Specification for constituent materials and concrete
Technical References
Refer to the following technical reference for guidance in carrying out the Works:
(a)
CONQUAS, Quality Standards for Civil and Structural Works
(b)
BCA Buildability Series Publications, Reference Guide on Standard Prefabricated Building Components
(c)
BCA Buildability Series Publications, Structural Precast Concrete Handbook (2nd Edition)
1.4
Trade Preamble
1.4.1
Contractor’s Submissions and Proposals
The layout and design intent of the concrete structures are shown in the drawings. Based on the design intent,
engage qualified and experienced personnel, including a PE where appropriate, to carry out the following
proposals for the Works, for the SOs acceptance.
Make relevant submissions to the authorities for approval as directed. All structural calculations and drawings shall
be endorsed by the PE, and comply with statutory requirements for approval, where applicable.
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1.4.1.1
S1.4.1.1
Not In Use
Develop the design of precast concrete elements
Develop the design to produce the necessary details for fabrication and incorporation of the precast elements to
the main structure for the SO’s acceptance. Cover the items as indicated in the drawings and shall include the
following items when developing the design, where applicable or directed by the SO:
Note: Use this clause amended as required where the Contractor is required to do design work. The appropriate
insertions will also be required in the contract documents to cover responsibilities, design warranties etc, where
there are particular requirements concerning the connections ensure that the following information is provided:
1.4.1.2
(a)
Structural design of the elements in the permanent building structure, including temporary stages
(b)
Design for prestress, covering both temporary and permanent states
(c)
Design for demoulding stresses
(d)
Design for lifting, handling, transporting and storage
(e)
Design for all connections and joints
(f)
Not In Use
S(f)
Design for waterproofing of the permanent structure and joints
(g)
Sequence of forming the joint;
(h)
Critical dimensions allowing for permitted deviations, e.g. minimum permissible bearing;
(i)
Critical details, e.g. accurate location required for a particular reinforcing bar;
(j)
Method of correction of possible lack of fit in the joint
(k)
Details of temporary propping and time when it may be removed
(l)
Description of general stability of the structure with details of any necessary temporary bracing;
(m)
Extent to which the uncompleted structure may proceed above the completed and matured section;
(n)
Details of any special materials
(o)
Fully specified weld sizes.
Mould and Formwork
Design all mould and formwork for the fabrication of the precast elements, including all accessories for the lifting,
handling and storage of the elements.
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1.4.1.3
Temporary Supports
Provide all necessary temporary supports and ensure that the precast elements are stable after erection but
before the completion of the building structure.
Provide all necessary precautionary measures to ensure that any part of the concrete structures is not subjected
to loads that will cause short- or long-term distress.
1.4.2
Shop Fabrication Drawings
Engage qualified personnel to develop the design drawings and produce shop fabrication drawings for the
fabrication of the precast elements. Submit all shop fabrication drawings for SOs acceptance prior to fabrication.
1.4.3
Maintenance/Replacement Manual
Prepare and submit a maintenance/replacement manual for components and connections, including the following
items, where applicable or directed by the SO :
(a)
Joint Sealant system
(b)
Structural steel connection and fasteners
(c)
Sliding joint membrane /pad
Refer to Section G01-010:Clause:1.4.5 for details.
1.4.4
Quality Control Plan
Submit and work to a quality control plan as agreed with the SO. Refer to Section G01-010:Clause:1.4.7.
S1.5
Supervision of Precast Structural Elements
For precast structural elements which are manufactured off-site in Singapore or overseas, the Contractor shall appoint a
Qualified Person (QP) to supervise the construction of the precast structural elements. The Contractor shall apply for a separate
permit to commence works to the Commissioner of Building Control. The appointed QP shall submit a certificate of supervision
of the precast structural elements on a daily basis or frequency agreed with the SO. The appointed QP shall appoint, if required,
accredited site supervisor(s) to assist him in the supervision of the construction of the precast structural elements. All work and
appointment of personnel related to the supervision of precast structural elements shall be deemed to have been included in the
Contractor’s pricing and programme.
2
PERFORMANCE REQUIREMENTS
2.1
Contractor’s Proposal Brief
In carrying out the design and proposals in Section C03-060:Clause:1.4.1, account for the input
requirements as set out below.
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2.1.1
Design Code
The design of precast concrete elements shall be in accordance with SS EN 1992 and SS CP 81.
2.1.2
Design Consideration
The elements shall be designed and detailed for all stresses induced by the worst loads, movement, creep
and shrinkage during the intended design life.
The elements, inserts or fixings, and positions shall be capable of resisting all stresses induced during the
processes of manufacturing, lifting/handling, demoulding, transportation, storage and erection.
The lifting and erection inserts, lifting hooks and erection devices shall be in compliance with the SS Eurocodes and
standards as appropriate.
As a minimum, the design loads and actions shall comply with requirements in the SS Eurocodes and the
Building Control Regulations. Refer to the design drawings for other information on any specific design loadings
if any.
Consider additional design requirements for the precast elements as shown in the drawings and shall include the
following, where applicable or directed by the SO:
2.1.3
(a)
Construction loads arising from adoption of construction method
(b)
Propped or unpropped horizontal precast structure construction during erection
(c)
Semi-precast individual element strengthening at erection stage, etc.
Joints and Connections
The joints and connections shall be designed to transmit all forces developed at the joints of structures.
When proprietary mechanical connection system is proposed, for the consideration of Design for Manufacture and
Assembly (DfMA), product technical specifications and verification testing etc. shall be submitted to the SO for
acceptance, and development of necessary quality control procedure during implementation.
Joints, connections and sealants shall be designed for protection against water, weather, corrosion and fire to
provide continued watertightness and weathertightness, and structural integrity of the buildings.
2.1.4
Water Retaining Structures
In the case of water retaining structures, design the elements for maximum crack width as specified in the
drawings or as directed by the SO, or otherwise in accordance with SS EN 1992-3 on allowable limits, for
durability and low permeability against water seepage.
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2.2
Fabrication
Ensure the precast concrete elements are fabricated in a manner that when erected and all connections are in
place, the design intent of the overall structure is achieved.
Incorporate the requirements of all other trades with work requiring blockouts, recesses, notches, embedded metals
or any other items.
Ensure that exposed final concrete surfaces or finishes of the precast concrete elements are structurally sound and
of the required concrete surface finishes that are smooth, and free from honeycomb and unacceptable bubble
holes.
In general, ensure that workmanship requirements as set out in the CONQUAS, "Quality Standards for Precast
Components" are met.
Ensure that the specified architectural finishes requirements, as indicated in the design drawings or as directed by
the SO, are achieved.
2.2.1
Manufacturing Requirements
Appointment of precast component manufacturer/supplier shall be approved by the SO, which is subject to the
manufacturer/supplier having the necessary licence granted by the BCA with accreditation of quality control
system and production facilities in its factory.
Prior to mass production of precast concrete components, produce at yard for the SOs approval, each type of
the following precast components: one mock-up of each major type of element, such as one façade; one
wall; one column; one staircase and one household shelter as agreed with SO. The SO may at his absolute
discretion require more sample panels to be produced for his/her approval.
Provide remedial work to precast concrete components that are not satisfactorily manufactured as directed by the
SO. Replace the precast concrete components that are rejected by the SO as a result of gross variation from the
specified surface finishes. Position all reinforcements in the moulds with the prescribed concrete covers as
shown in the Structural Drawings. Seek approval from the SO if such work cannot be incorporated into the
precast concrete components.
Aluminium window frames may either be installed on site or cast-in together with the precast concrete components.
In all cases, protect the aluminium window frames with suitable wrapping and temporary bracing against
deformation during concreting, and after production, protect from dirt, grout and other deleterious material by
additional cushion protection wrapping with self-adhesive protective tape, etc. prior to delivery. Ensure adequate
lapping over the joints of 2 protective tapes. Ensure protective tapes completely adhere to the frame and
provide protection.
In the case of aluminium window frames being installed on site, check and ensure:
(a)
The safety and integrity of the aluminium window frames and that no part of the precast concrete sill is
hacked;
(b)
The watertightness between the aluminium window frames and precast concrete components with
approved grouting and sealant.
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2.2.2
Inspection of Manufacturing
Make provision for the SO to inspect the manufacturing plant and the precast concrete components at all times.
Any precast concrete component on site and at the manufacturing plant that does not comply with the design
requirements and/or approved quality checking procedures shall be rejected by the SO.
2.3
Erection
Erect the precast concrete elements at the designated location in accordance with the design intention. Any
deviation shall be within the acceptable tolerance limit as specified in Section C03-060:Clause:4.3.3.
2.4
Joints and Connections
Fabricate and erect the elements in such manner that the joints are in accordance with the design and detail.
Any deviation in the joint width shall be within the acceptable tolerance such that the effectiveness of the joint’s
resistance against the forces shall not be affected, and the joint is protected from water, weather, corrosion and
fire, where applicable.
Connection details shall be compatible with the design assumptions for the precast concrete structure. Materials
used for connections shall be robust and compatible with the durability requirements of the overall structure.
Avoid harmful bimetallic contacts, which may result in galvanic corrosion.
3
MATERIALS
3.1
Moulds
Check and ensure that all moulds, regardless of materials, conform to the shape, lines and dimensions of the
precast concrete elements to be fabricated.
The moulds shall be sufficiently rigid to produce the casting tolerances and finishes specified.
Use rubber seal or equivalent, in all horizontal and vertical mould joints to prevent leakage of mortar or cement
paste.
Design the moulds to prevent damage to the concrete, at all stages, during concreting, curing and demoulding, from
the following:
(a)
Restraint, as the concrete shrinks
(b)
Stripping operation, when the precast concrete elements are lifted from the mould
(c)
Dimensional changes due to demoulding of precast concrete elements.
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Use rubber lining with sufficient rigidity and consistency to allow repeated use for achieving a consistent quality of
patterned finish.
Use high quality rubber mat with dimension stability with SOs acceptance, for carrying the tiles of precast
concrete elements with tile finish.
Self-vibrating table moulds or suitably incorporated form vibrators may be used, subject to satisfactory
demonstration of the component quality achieved in terms of compaction and surface finish using the mix
proposed for the fabrication of the elements.
3.2
Concrete
Refer to Section C03-010:Clause:3 for general requirements for material of concrete.
For material requirements in ferrocement products refer to Section C03-090-01 "Ferrocement".
3.3
Reinforcement
Refer to Section C03-020:Clause:3, for general requirements for material of reinforcement.
3.4
Prestressing Components
Refer to Section C03-070:Clause:3, for general material requirement for prestressing.
3.5
Structural Steel Components
Refer to Section C05-010:Clause:3, for general material requirement for structural steel component in the
precast elements, and Section C05-020:Clause:3 for the corrosion protection of such components.
3.6
S3.6
Not In Use
Non-Shrink Grout
Non-shrink grout for structural bedding of precast concrete elements shall be of at least the same strength
as the concrete of the building structures, or higher as required in the design.
The grout shall be able to minimise stress induced arising from shrinkage, which causes cracks along the
interface between the grout and the precast concrete elements.
Proprietary products may be used as an alternative to mortar or non-shrink grout, subject to the SO’s
acceptance. Demonstrate compliance of the product with the specified requirements.
Grout material to comply with SS EN 197-1 and BS EN 13139
3.7
Mortar
Mortar for non-structural bedding of precast concrete elements shall be made of sand, cement and water in
proportions by volume of the following:
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(a)
One part of Portland cement to SS EN 197-1
(b)
Two parts of sand to SS EN 12620
Determine the quantity of water required to achieve a mix suitable for jointing details shown on the drawings. Do not
add other ingredients without the SOs approval.
Mortar designated as dry-pack for non-structural bedding of precast concrete elements shall be of a tacky mix
consistency that can be properly compacted by external ramming prior to setting upon precast installation.
3.8
Permanent Inserts or Fixings
Cast-in inserts or fixings which would be permanently exposed either externally or within the cavity of the building
envelope shall be of corrosion resistant material, e.g. hot-dip galvanised, painted mild steel or stainless steel,
subject to the SOs acceptance. In other situations, agree with the SO on any protective treatment required.
3.9
Waterproofing
Refer to Section C03-050:Clause:3, for general requirements of material for concrete waterproofing.
3.9.1
Sealant
Refer to Section C03-050:Clause:3.8.1. Use suitable backer rod at joints where sealant is required for
waterproofing.
3.9.2
Waterproofing and Sealant Materials for Joints
3.9.2.1
General Requirements
The SO reserves the right to reject the use of any type of sealants if their performances is deemed unsatisfactory.
All sealant materials used at public accessible areas such as common corridors, stair-cases, stair- landings, etc.
shall be protected with non-shrink mortar or grout where appropriate or directed by the SO.
3.9.2.2
Application of Sealant Materials
Ensure that joints and joint sealants of precast concrete structures are correctly installed to provide continued
watertightness and weathertightness of building with minimum maintenance.
Joint surface preparation, primers, sealant compounds and backup materials shall be installed to give the highest
standard of materials and workmanship which shall conform to all applicable requirements as specified in the
Specifications.
Whenever possible, sealants shall be applied with a power-actuated gun. The gun shall have a nozzle of proper
size and provide sufficient pressure to completely fill the joints.
All compound smears, primers, solvents, etc. used in caulking and sealing work, shall be immediately and
entirely removed from adjacent materials as the work progresses.
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3.9.2.3
Joint Width and Sealant Depth After Installation
The joint width shall depend on the dimension of the panels and the coefficient of expansion.
Unless otherwise agreed by the SO, the maximum joint widths and maximum expansions for the
common sealants shall be as listed in Table 1:
Table 1. Common Sealants - Maximum joint widths and expansions
Type of Sealant
Butyl
Acrylic
One Part Polyurethane
Two Parts Polyurethane
One Part Polysulphide
Two Parts Polysulphide
Maximum
Joint Width
(mm)
Maximum Movement in
Tension or Compression
(%)
20
20
20
20
20
20
± 10
± 15 to ± 25
± 20
± 25
± 25
± 25
The normal design joint widths shall be 14 or 15, 25, as shown in the structural drawings.
For joints up to 13 mm wide, the depth of the sealant shall be equal to the width. For joints over 13 mm wide, the
depth shall be equal to 1/2 the width, but not less than 13 mm.
Sealants installed shall not be less than 6 mm wide or 6 mm deep.
3.9.2.4
Sealant Backup Fillers
Backup filler shall be used to with joints to control the depth of the sealant, to facilitate tooling of the sealant,
and to serve as a bond breaker which prevents the bonding to the back of the joint.
Acceptable backup materials shall be those which compress and respond to movement. These include the rod
type of sponge materials such as foamed polyethylene, polystyrene, polyurethane, polyvinyl chloride or
synthetic rubber. The backup materials shall also be compatible and non-staining to the selected sealants.
3.9.2.5
Joint Preparation
Before sealing the joints, ensure concrete surfaces are smooth, clean and free of all mortar dust or other
contaminants that may affect adhesion. Sealant and primer shall be supplied by the same manufacturer, and the
primer shall be as recommended for the particular sealant used.
3.10
Jointing
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3.10.1
General
Refer to SS EN 1992.
Grout, mortar-pack or concrete the load bearing joints and connections. Ensure the method of installation
adopted can fully grout, mortar-pack or concrete the joints and connections.
Fill non-load bearing joints between precast concrete components and adjoining structures with
appropriate grout and/or mortar protected by proprietary sealants and backing rod.
Apply special coatings or epoxy bonding compounds to connections and joints of precast concrete components,
whether welded, bolted, dowelled, grouted, mortar-packed or concreted, as instructed or directed by the SO.
3.10.2
Sleeve for Rebar Jointing
Use one of the following types of sleeve connectors subject to satisfactory tests to determine structural strength and
deformation characteristics:
(a)
Grouted, resin-filled or swaged sleeve capable of transmitting both tensile and compressive forces
according to design requirement
(b)
Sleeve connectors that mechanically align the square-sawn ends of 2 bars to allow the transmission of
compressive forces only
Submit proposals and details of sleeve connector for joints to the SO for acceptance, including
information on product manufacturer and model.
Provide the proprietary product or approved equivalent of sleeve connector for joints as shown in the drawings or
as directed by the SO.
3.10.3
Welding
Refer to Section C03-020:Clause:4.3.3 for welding of reinforcement and Section C05-010:Clause:4.5 and
Section C05-010:Clause:5 for welding of structural steel components.
3.11
Precast Prestressed Concrete Plank
3.11.1
Design Criteria and Material for Precast Prestressed Concrete Plank
Low slump concrete shall be used for the production of precast prestressed concrete plank. The strength of concrete
at 28 days shall be of a minimum grade of C32/40 or specified design grade, and at transfer, shall not be less
than 25 N/mm². The use of calcium chloride, ion or other salts is strictly prohibited.
The minimum grade of concrete for the cast-in-situ structural topping shall be C32/40.
Submit for the SOs approval the initial prestressing records and the allowable strands slippage for plank
production.
3.12
Precast Prestressed Hollow Core Slab
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3.12.1
Design Criteria and Material for Precast Prestressed Hollow Core Slab
The requirements for precast prestressed hollow core slab shall be the same as those specified for the precast
prestressed concrete plank, except that the transfer strength for concrete shall not be less than 30 N/mm².
3.13
Precast Ferrocement Sun-breakers
All structural and architectural drawings on this provision shall only serve as a guide. Where required or specified
in the drawings, prepare and submit workshop drawings for the SOs acceptance on all relevant details,
including:
(a)
Details on reinforcement of sun-breaker panels in elevations and sections.
(b)
Fixing and connection details.
(c)
Necessary steel bolts, hooks or other approved materials required for handling and erection purposes.
Indicate the size and location of these materials clearly in the details.
[Note 1: Consider the durability aspects with the local experience of more than twenty years on the use of
precast ferrocement sun-breakers. If used, consider specifying limits on the size and or weight of ferrocement
panels to avoid large panels.]
3.13.1
Steel Reinforcement
Steel reinforcement shall be as specified in Section C03-020, including all sub-clauses under it. In addition, all
welded mesh and steel bar used shall be galvanised in accordance with BS EN ISO 1461.
Wire mesh with 1.5 mm diameter at 25 mm spacing shall be galvanised with zinc coating of 325 g per m² and
250 g per m² minimum for average coating. Local coating shall have minimum proof stress of 300 N per mm².
3.13.2
Technical Specifications
3.13.2.1
Ferrocement Mix Design
The ferrocement sun-breaker panels shall be cast from a mix design satisfying the following
requirements:
(a)
Minimum cement to sand ratio by weight of 1:2
(b)
Maximum water to cement ratio by weight of 0.45
(c)
Air dry density of hardened concrete (including steel) not less than 2,200 kg/m²
(d)
28 days-average cube strength from 3 test cubes shall be not less than 40 N per mm²
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The amount of admixture in the mix design shall be in accordance with the manufacturer's instruction. Before
commencing, the manufacture of precast ferrocement sun-breaker, submit a proposed mix design to the SO
for approval.
3.13.2.2
Other Properties
(a)
Initial Surface Absorption Test (ISAT) shall be carried out in accordance with BS 1881. The hardened
panel shall have ISAT value less than that stipulated below:
Table 2. ISAT values of hardened panel
Time (min)
ISAT Value (m/m²/s)
3.13.2.3
10
0.100
30
0.055
60
0.035
(b)
Carbonation depth of hardened panel at installation shall be less than 3 mm.
(c)
Cover tolerance shall be such that no more than 3 points per section shall have a cover measurement of
less than 5 mm, but not less than 3 mm.
Finishes
The panel shall be cast on a steel base mould with the finish surface cast-face down. The finish surface is the
external surface of the sun-breaker elevation where the tile and motifs are located.
3.13.2.4
Dimensional Tolerances
All tolerances shall be as specified in sub-clauses in "Manufacturing Tolerances" and in "Erection Tolerance".
3.13.3
Manufacturing Process
The panel shall be cast flat on a steel base mould. The mortar shall be compacted by vibrators and the top
surface shall be steel trowelled smooth. All reinforcement shall be galvanised and adequately supported with
approved spacers.
After setting and demoulding, mark the panels and neatly store with easy access and visibility to every piece.
All panels must be properly cured. Seek the approval of the SO with respect to the curing method, duration
and facilitates prior to actual production. The curing method shall be equivalent to 3 days of moist curing.
Prior to commencement of the production, at least one sample of the panels shall be produced, erected and
installed at site for the approval of the SO. Make adjustments to the manufacturing process or equipment if
so directed by the SO.
Maintain a record of daily work progress on a proper drawing showing where panels of a particular date of
manufacture have been installed.
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3.13.4
Quality Assurance Works for Precast Ferrocement Sun-breakers
For precast ferrocement sun-breakers, the requirements for inspection and testing, sampling rate and passing
criteria shall be as submitted to the SO for acceptance and development of necessary quality control procedure,
or as directed by the SO.
3.14
Precast Facades with Cast-in Window Frame
3.14.1
Protection of Cast-In Window Frames
Ensure that cast-in window frames are protected from damage before delivery to precast plant.
Protect cast-in window frames from dirt, grout, grease, deleterious materials and surface scratch with quality
translucent self-adhesive tape of light colour for inspection of window frame quality at precast plant prior to
casting, as well as for inspection at site upon the delivery of precast facades. The self- adhesive tape shall be
made of durable material that can withstand the weathering. The protective tape shall not stain or stick to the
aluminium surface, or leave a sticky surface upon the removal.
During manufacturing of precast component, the cast-in window frame shall be properly braced and secured to
position such that it will not move or deform during concreting. Ensure that the wrapping with self-adhesive tape is
robust to withstand handling during casting, storage and transportation to site. The adhesive tape shall be intact
with cast-in window frame along the edges with no visible gaps.
The corners of cast-in window frames and intersections of window frame members shall be adequately wrapped
with sufficient laps and returns to prevent ingress of concrete grout during casting. All fastening screws, joints and
gaps that are in contact with the wet concrete shall be sealed adequately to prevent grout ingress during casting.
Cast-in window frames with torn, loose wrappings, and frames with visible gaps at edges that will be in contact
with wet concrete shall not be used for casting. Poorly protected window frames shall be made good or replaced.
3.14.2
Quality Control at Window Factory
Ensure that adequate quality assurance measures are in place in the production and the assembly of cast-in
window frames. Quality assurance checks on surface defects such as dents, scratches and other defects such as
dimension out of the manufacturing tolerances, warpage, twisting, skewing, track misalignment, shall be
conducted at the window factory before wrapping up with the protective tape.
A label sticker shall be provided at one location on the internal face of cast-in window frame to indicate the
product serial number, window marking (including its orientation such as top, left or right-hand side, if applicable)
on each cast-in window frame. This is to facilitate down-stream traceability and inspections, and prevent mistakes
in the placement of window frame in precast production.
For sliding window, provide internal bracing to control the sagging of horizontal aluminium members adjacent to the
window opening during handling and precast production process.
The cost for measures taken to enhance the window identification, to control the alignment of aluminium members
during handling and for quality assurance in precast production is deemed to have been included in the tender
sum.
3.14.3
Quality Control at Precast Plant
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3.14.3.1
Inspection Upon the Delivery of Cast-In Window Frames
Ensure that cast-in window frames delivered to precast plant are of good quality at the point of receiving. The
inspections at precast plant shall include, but shall not be limited to, inspections on the workmanship of protective
wrapping, dimension and surface defects such as dents and scratches.
3.14.3.2
Storage of Cast-in Window Frames
Store cast-in window frames at a sheltered yard to prevent deterioration of protection system due to weathering.
The storage shall be demarcated, barricaded and raised to prevent soiling, contacting with deleterious materials
and accidental damage.
3.14.3.3
Care and Protection During Casting and Transportation
Ensure cast-in window frames are handled with care during the production process. Assign experienced personnel,
including supervisors and a team of skilled workers with the SOs acceptance for the production of precast facades
with cast-in window frames, repair and delivery.
Any part of cast-in window frames which is in direct contact with the dummy frames, bracings and stoppers of the
mould system, additional protective material shall be provided to prevent any premature damage to the cast-in
window frames. Additional protection may be needed to prevent grout leakage at the comers. To avoid excessive
staining due to dropping of fresh concrete, protective measures shall be taken to cover the window frames during
the casting process. For the transportation from precast plant to site, provide adequate measures at the critical
contact points between the precast facades and the steel frames on the trailers to prevent damage to the cast-in
window frame.
Before casting, exercise due diligence and care in the precast production to ensure that the orientation of cast-in
window frame is checked when it is placed on the mould. Measure and check the position of the cast-in
window frame against the approved precast shop drawings before casting. Upon the demoulding of precast
facades, the orientation, position of cast-in window frame and the clearance between the aluminium members
shall be measured to detect any possible sagging or bulging occurred during the casting.
3.14.3.4
Watertightness Test
Provide the equipment, labour and material to conduct watertightness test at the precast plant to ensure there is no
water seepage at the interface joint between the cast-in window frame and adjacent concrete.
The watertightness test shall be carried out using a continuous jet of water sprayed on the joint/interface with a
nozzle and water hose. For each window, 4 points shall be selected for testing and each point shall be sprayed
for 20 min. The location of test shall be selected by the SO. The velocity of the water at each nozzle shall be 2 m
per second. The capacity of the water delivered from each nozzle shall be 600 litres per hour. Hold the nozzle
at a distance 1 m away from the joint/interface and pointed towards the joint/interface horizontally.
Test 10% of the precast facades with cast-in window frame for the watertightness at the interface joint. Carry
out the watertightness test as soon as the precast production has commenced to ascertain the initial casting
workmanship, as well as the performance of the cast-in window frames. Submit for the SOs approval on the
window type or window configuration and the location on window frame to be tested. The percentage of testing
required with the agreement by the SO shall depend on the quality and performance cast-in window and the test
results.
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3.14.3.5
Functional Test
For quality assurance, check the functionality and the performance of cast-in window frames randomly at the
early stage of the project. This is to ensure that any inadequacy of the bracing system can be detected early.
For sliding windows, the inner frames shall be installed for repeated sliding operations to check for smoothness,
alignment and safety in operation. For casement and top-hung windows, the inner frames shall be tested by
repeated opening and closing to check for smoothness, alignment and safety.
3.14.4
Inspection and Protection on Site
3.14.4.1
Inspection on Delivery of Precast Facades with Cast-In Window Frames
When precast facades with cast-in window frames are delivered to site, check the condition of the cast-in window
frames before installation.
3.14.4.2
Protection of Precast Facades with Cast-in Window Frames
The precast components with cast-in window frames delivered to site are protected with the translucent selfadhesive tape. Provide additional protective material such as bubble wrap of minimum thickness of 5 mm or any
other materials which are equivalent in performance and subject to the approval of SO to further protect the
cast-in window frames from impact and abrasive forces on site.
3.14.5
Submission of Window Shop Drawings and Delivery of Cast-in Window Frames to Precast Plant
Submit the window shop drawings to SO for approval within a reasonable time frame from the date of the
Letter of Acceptance. The time frame for the window shop drawing submission shall be tied in with the approved
master construction programme for the initial delivery schedule of precast components to prevent any delay in
precast supply.
Deliver mock-up cast-in window frames to the precast plant to facilitate the mould fabrication at the window
opening. The time frame for the delivery of mock-up window frames shall be carefully planned to tie in with the
initial delivery schedule of precast components to site and tie in with the approved master construction
programme.
Provide the mock-up frames, make improvements in the protective wrapping, including increasing the number of
layers if required to enhance grout tightness, and on window frame construction where necessary.
Ensure sufficient lead time in the deliver