MAINTENANCE MANUAL
MM (H) XX/201Y
FEATURE NO. Feature no.
Location
AUTHOR
This manual has been prepared for the sole and specific use of the
Government of the Hong Kong Special Administrative Region. Any other
persons who use any information in it do so at their own risk.
November 2011
Landslip Preventive Measures Division 2
GEO
2
Revision Record
Revision
Date
number
B
7/201Y
A
1/201Y
Description
Prepared
Checked
Approved
General revision to format
General revision to format
ABC
DEF
GHI
3
Foreword
Feature No. Feature no. is a stabilization measure (NS)
/defence measure (ND)* at Location.
LPM Division 2 of Geotechnical Engineering Office,
Civil Engineering and Development Department carried out /
[Name of Consultant] was commissioned by the Geotechnical
Engineering Office, Civil Engineering and Development
Department under Consultancy Agreement No. CE XX/YYYY
(GE) to carry out* a Stage 3(H) Study (Stage 3(H) Report No.
S3(H)R xx/yyyy) for the Natural Terrain Hazard Mitigation
Measures.
This Maintenance Manual summarizes the landslide
mitigation works carried out and the maintenance requirements
of the Natural Terrain Hazard Mitigation Measures. This
Manual also contains the results of the design review during
construction. Depending on the outcome of the review, the
design model finally adopted and therefore shown in this report
may be different from that in the corresponding Stage 3(H)
Study Report.
(
)
Chief Geotechnical Engineer/LPM Division 2
*Approved by: ________________________
<Name>
Project Director
[Name of Consultant]
*Delete as necessary.
4
Contents
Page
No.
1
General Advice
5
2
Recommended Maintenance
6
3
Contract/Works Details
8
4
Record Sheets and As-built Drawings
9
Appendix I
List of Features
10
Appendix II
Location Plan of Features Listed in Appendix I
12
Appendix III
Record Sheets of Features Listed in Appendix I
14
Appendix IV
Typical Record Sheets for Routine Maintenance
Inspections and Works
19
Contract Summary of the Landslip Prevention and
Mitigation Works Carried Out
25
Appendix VI
Design Approach, Parameters and Method of Analysis
27
Appendix VII
Verification of the Design Geological Model
30
Appendix VIII
Brief Records of Construction Review
32
Appendix IX
Summary of Previous Studies Carried Out
34
Appendix X
As-built Drawings
36
Appendix XI
Other Specific Maintenance Requirements for the Defence
Measures
39
Certificate of Design and Completion of Natural Terrain
Hazard Mitigation Measures
40
GEO Checking Certificate for Natural Terrain Hazard
Mitigation Measures
43
Appendix V
GCD 115
GCD 116
5
This maintenance manual consists of four parts:
1
General Advice
1.1
Feature No. Feature no., at Location for which you have maintenance responsibility has
been constructed under Contract No. GE/XXXX/XX managed by the Geotechnical
Engineering Office (GEO), Civil Engineering and Development Department.
1.2
It was agreed in the Standing Committee on Slope Safety meeting of 21.12.2001 that
natural terrain mitigation measures have to be maintained. Further technical guidance is
provided in Geoguide 5 - Guide to Slope Maintenance (2003) published by the GEO.
1.3
Technical guidelines on landscape maintenance and management are given in GEO
Publication No. 1/2000 – Technical Guidelines on Landscape Treatment and Bio-engineering
for Man-made Slopes and Retaining Walls. The vegetation planted should be maintenance
free. In the situation that they are damaged (e.g. by hill fire, landslide, etc.), they should be revegetated with similar species.
1.4
Maintenance departments are urged not to replace vegetation on slope surfaces by
chunam or sprayed concrete as part of routine maintenance works. WBTC No. 25/93 includes
guidelines on the ‘Control of Visual Impact of Slopes’.
1.5
For the continued satisfactory performance of the mitigation measures, regular
maintenance including the upkeep of the physical integrity as well as the landscaping and bioengineering works is essential and the recommendations contained in the relevant
Circular/Geoguide/GEO Publication should be followed.
1.6
This manual provides information and specific advice for your future maintenance of
the slope. You should follow the specific recommendations on maintenance given in Part 2 of
this Manual.
1.7
Parts 3 and 4 of this Manual provide you with the construction details and other
relevant information for your maintenance works.
6
2
2.1
Recommended Maintenance
You are advised to carry out the following:

Routine Maintenance Inspection to be carried out annually before the onset of
the wet season;
(Others to be specified) (Note 1);
2.2
Routine Maintenance Inspection
Routine Maintenance Inspections should cover the measures, the area containing the
measures and the adjoining ground. They should preferably be carried out between October
and February, and any required maintenance works should be completed before the onset of
the wet season in April. These maintenance inspections should be undertaken by your
Assistant Clerk of Works, Technical Officer, Works Supervisor or above, as appropriate, who
should make recommendations with regard to the following maintenance items (such
inspecting officers are expected to have the knowledge of and experience in recommending
the list of maintenance items including those related to landscape softworks):
1

clearance of accumulated debris from drainage channels and slope surface,
catch trenches and pits, containment basins and straining structures;

repair of cracked or damaged drainage channels or pavements and retaining
wall;

repair of or replacement of cracked or damaged hard slope surface cover or
sections;

removal of any vegetation that has caused severe cracking of slope surface
cover and drainage channels;

removal of loose rock debris and undesirable vegetation from rock slopes or
around boulders;

re-grassing of bare soil slope surface areas;

repair of missing or deteriorated pointing in masonry walls;

unblocking of weepholes and outlet drainpipes;

repair of / notification to relevant parties of leaky exposed water-carrying
services;
Engineer Inspections for Maintenance are not normally required unless specified by the designer or in special
provisions. Geoguide 5 Section 7.5 refers.
7

repair of or replacement of rusted steel furniture;

removal of accumulated debris behind the debris/rockfall barriers;

repair of or replacement of damaged components of the debris/rockfall barriers;

maintenance of landscape items or bio-engineering works;

repair of or reinstatement of the ground adjoining the measures if affected by
severe erosion;

repair of or reinstatement of the pavement of the associated vehicular
maintenance access and the adjoining drainage channels, slopes, retaining walls
and the other geotechnical features if found necessary;

removal of Mikania micrantha (薇甘菊), if any, from the slope surface;

removal of Leucaena leucocephala (銀合歡) seedlings, if any, from the slope
surface (Note 2);
(others to be specified to upkeep the integrity and function of the measures, e.g.
specific maintenance requirement from the supplier of any defence measures).
In cases where unusual conditions or problems are observed during routine
maintenance inspections, e.g. a check dam filled up with a large amount of landslide debris or
significant movement observed at boulders supported by buttresses, the owner or the party
required to maintain the mitigation measures should seek advice from a professionallyqualified geotechnical engineer and inform the Landslip Investigation Section of LPM
Division 1 of GEO.
The records of Routine Maintenance Inspection should be properly made and kept.
Typical Routine Maintenance Inspection record sheets are attached as Appendix IV.
2.3
Other Specific Maintenance Requirements for the Defence Measures
Details shall refer to Appendix XI.
2
Refer to paragraph 33 of ETWB TCW 3/2006
8
3
Contract/Works Details
3.1
The details of the Contract and a summary of the Natural Terrain Hazard Mitigation
Measures carried out are given in Appendix V.
9
4
4.1
Record Sheets and As-built Drawings
The record sheets given in Appendix III provide detailed information with regard to:

Technical information such as the dimensions of the features, surface
conditions of the features, drainage details, consequence/susceptibility classes
and details of study/mitigation works;

Maintenance schedule such as a list of items requiring routine maintenance,
and frequency of maintenance inspections;

Location plan and site plan showing the extent of feature and the adjoining
maintenance access and geotechnical features to be maintained;

Plan/Sections of feature and the adjoining maintenance access and geotechnical
features to be maintained;

Layout plan of water-carrying services on or adjacent to the feature;

Record photographs.
4.2
The following drawings are the as-constructed drawings for the slope and are given in
Appendix X:

Drawing No.

Drawing No.
10
Appendix I
List of Features
11
Appendix I
List of Features – Submissions and File Reference
Consultant’s File Ref. No.
GEO’s File Ref. No.
Relevant Documents Checked
GEO Feature
No.(1)
Drg. No.
Report Title
Memo Reference
Memo Reference
and Date of
and Date of
Documents
Checker's
Submission to
Comments
Checker
Remarks
Notes:
(1)
If GEO Feature No. is not available, provide a reference no. shown in the location plans at Appendix II.
12
Appendix II
Location Plan of Features Listed in Appendix I
13
Outline the boundary of
natural hillside catchment and
highlight the extent of the
feature required maintenance
in this location plan with
different legend.
Appendix II – Location Plan of Features listed in Appendix I
14
Appendix III
Record Sheets of Features Listed in Appendix I
15
MAINTENANCE MANUAL FOR NATURAL TERRAIN
(SHEET 1 OF 4)
HAZARD MITIGATION MEASURES
FEATURE REFERENCE NO. (1) Feature no.
Location (address) Location
Date
of
Construction
Map Co-ordinates (1980 DATUM)
Easting
Northing
Purpose of the Natural Terrain Hazard Mitigation Measures:
TECHNICAL INFORMATION (continue on separate sheets if necessary)
Stabilisation Measures(2)
 Boulder Buttresses:
Total No. of Buttresses:
 Soil Nails:
Total No. of Soil Nails Installed:
Maximum Length of Soil Nails (m):
 Raking Drains:
Total No. of Raking Drains:
Maximum Length of Raking Drains (m):
Others:
Defence Measures(2)
Types of Measures: Check Dam/ Earth Bund / Boulder Fence / Other: Containment Structure
Typical Dimensions:
Others:
MAINTENANCE REQUIREMENTS
Frequency of Routine Maintenance Inspections:
Man-made Items for Maintenance:
Guidelines on seeking geotechnical engineer’s advice:
INFORMATION PROVIDER
Records prepared by:
Firm:
Signature:
Date:
Note:
(1) Upon request, the Geotechnical Engineering Office can provide a reference number if applicable.
(2) Use a separate Sheet 1 for each type of defence measure. Different types of stabilisation measures (e.g.
buttresses and soil nails) in the same location can be considered as a group for record purpose.
Appendix III – Record Sheets of Features Listed In Appendix I (Sheet 1 of 4)
16
MAINTENANCE MANUAL FOR NATURAL TERRAIN
(SHEET 2 OF 4)
HAZARD MITIGATION MEASURES
FEATURE REFERENCE NO. Feature no.
LOCATION PLAN AND SITE PLAN (with scale and indication on access)
Appendix III – Record Sheets of Features Listed In Appendix I (Sheet 2 of 4)
17
MAINTENANCE MANUAL FOR NATURAL TERRAIN
(SHEET 3 OF 4)
HAZARD MITIGATION MEASURES
FEATURE REFERENCE NO. Feature no.
PLAN/SECTIONS OF FEATURE TO BE MAINTAINED
Refer to as-built Drawings in
this Maintenance Manual
Note:
All dimensions are in millimetres and all levels are in metres above Principal Datum.
Appendix III – Record Sheets of Features Listed In Appendix I (Sheet 3 of 4)
18
MAINTENANCE MANUAL FOR NATURAL TERRAIN
(SHEET 4 OF 4)
HAZARD MITIGATION MEASURES
FEATURE REFERENCE NO. Feature no.
RECORD PHOTOGRAPHS (with descriptions and date; and with the vantage points
indicated on the plans)
Note:
Add additional record sheets for photographs as necessary.
Appendix III – Record Sheets of Features Listed In Appendix I (Sheet 4 of 4)
19
Appendix IV
Typical Record Sheets for Routine Maintenance Inspections and Works
20
RECORD OF ROUTINE MAINTENANCE INSPECTION
(SHEET 1 OF 4)
FEATURE REFERENCE NO. (1)
Location (address)
Date of Inspection:
Weather Condition at Time of Inspection:
Maintenance Action Item
Location
Reference
Action
Required
No
Works
Completion
Date
Yes
Clear drainage channels of accumulated
debris
Repair
cracked/damaged
drainage
channels or pavements along crest and toe
of slope or retaining wall
Repair or replace cracked or damaged
impermeable slope surface cover
Remove surface debris and vegetation
that has caused severe cracking of slope
surface cover and drainage channels
Remove loose rock debris and
undesirable vegetation from rock slopes
or boulders
Re-vegetate bare soil slope surface
Repair pointings in masonry walls
Unblock weepholes and outlet drainpipes
Repair/notify relevant parties of leaky
exposed water-carrying services
Repair or replace rusted slope furniture
(e.g. steel gates, boundary fences and
stairs)
Remove debris from defence measures
Repair or replace damaged/corroded
components of defence measures (e.g.
wire ropes, anchor ropes and posts etc.)
Repair or replace the landscaping works
Others (specify works and give details)
Recommended Date for Completion of Above Works:
Notes:
(1) Upon request, the Geotechnical Engineering Office can provide a feature reference number if applicable.
Appendix IV - Typical Record Sheets for Routine Maintenance Inspections (Sheet 1 of 4)
21
RECORD OF ROUTINE MAINTENANCE INSPECTION
(SHEET 2 OF 4)
FEATURE REFERENCE NO.
SITE PLAN (Reference numbers should be assigned to locations of man-made items for
which maintenance works are required. The corresponding reference numbers should be
quoted in the photographic records.)
Notes:
(1) Add additional record sheets for site plan as necessary.
Appendix IV - Typical Record Sheets for Routine Maintenance Inspections (Sheet 2 of 4)
22
RECORD OF ROUTINE MAINTENANCE INSPECTION
(SHEET 3 OF 4)
FEATURE REFERENCE NO.
Immediate advice from professionally-qualified geotechnical engineer needed (Yes/No)
(1)
?
Immediate arrangement for investigation and repair of exposed water-carrying
(Yes/No)
services needed?
OTHER OBSERVATIONS (continue on separate sheets if necessary)
(e.g. condition of trees for which specialist advice is needed)
Inspected by:
(Name of person undertaking inspection)
of
Signature:
(Organisation)
Date:
Due date of next inspection:
Received by:
(Name of owner or his authorised representative)
of
Signature:
(Organisation)
Date:
Note:
(1) Where unusual conditions or problems are observed, e.g. a check dam filled up with a large amount of
landslide debris or significant movement observed at boulders supported by buttresses, the case should be
reported to the owner or party responsible for the maintenance of the mitigation measures.
Appendix IV - Typical Record Sheets for Routine Maintenance Inspections (Sheet 3 of 4)
23
RECORD OF ROUTINE MAINTENANCE INSPECTION
(SHEET 4 OF 4)
FEATURE REFERENCE NO.
RECORD PHOTOGRAPHS (with descriptions, date, and reference numbers as given on the
site plan)
Notes:
(1) Add additional record sheets for photographs as necessary.
(2) Record photographs should show in detail areas where maintenance works are required and be annotated
with descriptions.
Appendix IV - Typical Record Sheets for Routine Maintenance Inspections (Sheet 4 of 4)
24
RECORD OF ROUTINE MAINTENANCE WORKS
(SHEET 1 OF 1)
FEATURE REFERENCE NO.
Maintenance works arranged by:
(Name)
of
Signature:
(Organisation)
Date:
Maintenance works carried out by:
(Name)
of
Signature:
(Organisation)
Date:
Maintenance works carried out on:
RECORD PHOTOGRAPHS (with descriptions, date, and reference numbers as given on the
site plan)
Notes:
(1) Add additional record sheets for photographs as necessary.
(2) For removal of loose rocks from rock face or clearing debris from defence measures, e.g. check dam, the
estimated volume of debris removed should be recorded.
(3) Record photographs should show in detail areas where maintenance works have been carried out and be
annotated with descriptions.
(4) Record photographs before and after the execution of maintenance works should be taken from the same
vantage points.
Appendix IV - Typical Record Sheet for Routine Maintenance Works (Sheet 1 of 1)
25
Appendix V
Contract Summary of the Landslip Prevention and Mitigation Works Carried Out
26
CONTRACT AND SUMMARY OF THE
LANDSLIP PREVENTION AND MITIGATION WORKS
CARRIED OUT
(SHEET 1 OF 1)
FEATURE REFERENCE NO. Feature no.
LOCATION (ADDRESS)
Location
SLOPE MAINTENANCE OFFICE
LANDSLIP PREVENTIVE MEASURES CONTRACT DETAILS
Contract No:
GE/xxxx/yy
Contractor:
Works commenced:
Works completed:
Maintenance period expired on:
Brief Description of Works Carried Out
Appendix V - Contract And Summary of the Landslip Preventive Works Carried Out (Sheet 1 of 1)
27
Appendix VI
Design Approach, Parameters and Method of Analysis
28
DESIGN APPROACH, PARAMETERS AND
METHOD OF ANALYSIS
(SHEET 1 OF 2)
DESIGN APPROACH
PARAMETERS
Soil Type
Colluvium
Completely Decomposed Granite
Highly Decomposed Granite
STABILITY ANALYSES
Factor of Safety
Bulk
Weight Cohesion
(kN/m3)
(kPa)
19
4
19
7
19
10
Before mitigation works
Angle of friction
(°)
28
37
40
After mitigation works
PLAN
Outline the design approach adopted and the method of analysis for the
stabilization/defence measure as appropriate
CRITICAL SECTION
Appendix VI – Design Approach, Parameters and Method of Analysis (Sheet 1 of 2)
29
DEBRIS MOBILITY MODELLING
(SHEET 2 OF 2)
DESIGN EVENT
DMM PARAMETERS
WCE/CE Volume
Mode of Potential Failure (Channelised
Debris Flow/Open Hillslope Failure)
Trapezoidal/rectangular cross section
Apparent Friction Angle
Cohesion
DMM Result
Debris Impact Load
Debris Depth
Debris Impact Velocity
PLAN
m3
°
kPa
Outline the design approach adopted and the method of analysis for the
stabilization/defence measure as appropriate
CRITICAL SECTION
Appendix VI –Design Approach, Parameters and Method of Analysis (Sheet 2 of 2)
30
Appendix VII
Verification of the Design Geological Model
31
VERIFICATION OF THE DESIGN GEOLOGICAL MODEL
Original Design
Verification / Amendments
during Construction
Date
(SHEET X OF Y)
Verified by
(Name/
Post/
Qualif.)
ign ic
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e
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Appendix VII – Verification of the Design Geological Model (Sheet X of Y)
32
Appendix VIII
Brief Records of Construction Review
33
BRIEF RECORDS OF CONSTRUCTION REVIEW
Design Details
Construction Review
Date
Fi
g
n
i
nd
s
ch
d
an
(SHEET X OF Y)
Reviewed by Approved
(Name/
by
Post/
(Name/
Qualif.)
Post/
Qualif.)
s
e
g
an
Appendix VIII - Brief Records of Construction Review (Sheet 1 of 1)
34
Appendix IX
Summary of Previous Studies Carried Out
35
SUMMARY OF PREVIOUS STUDIES CARRIED OUT
Type of study
LPM Consultant/GEO Division
Appendix IX - Summary of Previous Studies Carried Out
(SHEET 1 OF 1)
Date
36
Appendix X
As-built Drawings
37
[DRAWING NO. GED XXXXX/XX]
38
[DRAWING NO. GED XXXXX/XX]
39
Appendix XI
Other Specific Maintenance Requirements for the Defence Measures
40
GCD 115
Certificate of Design and Completion of Natural Terrain Hazard Mitigation Measures
41
Feature No. Feature no.
Certificate of Design and Completion of Natural Terrain Hazard Mitigation Works
(to be completed by Project or Maintenance Department/Office or their Consultants)
Name of Government Department/Office :
Name of Consultants :
Agreement No. and Title :
Contract No. and Title :
Appendix I : List of Features - Submissions and File Reference.
Appendix II : Location Plans of Features Listed in Appendix I
Appendix III : Record Sheets of Features Listed in Appendix I (Appendix A of Geoguide 5
refers)
Part 1 : Certificate of Design
We certify that :(a) we have exercised all reasonable skill and care to be expected of a professionally
qualified and competent person, experienced in work of a similar nature and scope, in
the performance of duties relating to the preparation, review, checking and certification
of the design and amendments of design of the natural terrain hazard mitigation
measures as shown and described in the submissions listed in Appendix I;
(b) the design and amendments of design shown in Appendix I complied with the relevant
standards at the time when they were carried out and an in-house independent check has
been undertaken and completed to confirm that they are complete, adequate, and valid,
and all conditions imposed under the Geotechnical Engineering Office’s checking
procedures in relation to these designs and amendments of design have been complied
with; and
(c) the design and amendments of design shown in Appendix I have been conveyed
accurately and completely to the Engineer for the Contract for execution.
Date :
Signed :
Name :
Designation:
Part 2 : Certificate of Completion
I certify that the natural terrain hazard mitigation measures listed in Appendix I have been
completed in accordance with the design and amendments of design as conveyed to me by the
designer.
Date :
Signed :
Name :
Designation:
GCD115 (1/2)
42
Feature No. Feature no.
Appendix I
List of Features - Submissions and File Reference
Consultant’s File Ref. No.
GEO’s File Ref. No.
Relevant Documents Checked
GEO Feature
No.(1)
Drg. No.
Report Title
Memo Reference
Memo Reference
and Date of
and Date of
Documents
Checker's
Submission to
Comments
Checker
Remarks
Notes:
(1)
If GEO Feature No. is not available, provide a reference no. shown in the location plans at Appendix II.
GCD115 (2/2)
43
GCD 116
GEO Checking Certificate for Natural Terrain Hazard Mitigation Measures
44
Feature No. Feature no.
File ref. :
GEO Checking Certificate for Natural Terrain Hazard Mitigation Measures
Checking Certificate No.: ---
Agreement No. and Title :
Contract No. and Title :
GCD 115
Certificate of Design and Completion of Natural Terrain Hazard Mitigation
Measures (Submitted by the Consultant / In-house Design Team*)
1.
I confirm that the design of the geotechnical features included in the Certificate of
Design and Completion of Natural Terrain Hazard Mitigation Measures as given in
GCD 115 has been found to be satisfactory under the Geotechnical Engineering
Office's checking requirements.
2.*
The geotechnical works for the geotechnical feature(s) given in GCD 115 were
constructed to mitigate the natural terrain hazard. Associated defensive measures
and/or stabilization measures were also constructed at geotechnical feature(s)
reference no. _________ to supplement the geotechnical works for the features in
GCD 115. It is noted that these measures were prescribed based on experience and
judgment of the designer and no detailed design/stability assessment* had been
carried out for them.
3.*
(Other qualifying statements to be included as appropriate, if any)
Date :
Signed :
(
)
Deputy Head of the Geotechnical Engineering Office
(Landslip Preventive Measures)
Civil Engineering and Development Department
* Delete whichever is not applicable.
GCD116 (1/1)
MM (H) XX/201Y