Technical Specifications
Water, Sewer and Drainage System Including Wastewater Treatment Plant
DIVISION 6
WATER, SEWER & DRAINAGE SYSTEM
INCLUDING WASTEWATER TREATMENT PLANT
6.3 DRAINAGE SYSTEM
6.3.1 DESCRIPTION
This work shall consist of the construction of drainage pipes, box culverts and ditches in
accordance with these Specifications and to the lines, grades and dimensions shown on
the drawings or ordered by the Engineer. It shall include the excavation and backfilling
works, furnishing and laying of the pipes and the construction of such joints and
connections to discharge outflow and/or accessories required to complete the work as
shown on the drawings or as required by the Engineer.
6.3.2 MATERIAL REQUIREMENTS
6.3.2.1 REINFORCED CONCRETE PIPE.
1. General Requirements for RC Pipe
The drainage pipes shall be tongue and groove and shall conform to the requirements of
ASTM C 76, Class II, or AASHTO M 170.
2. Compressive Strength of Concrete for RC Pipe
Concrete to be used shall conform to the requirements of Section 3.2, "Concrete Works"
and shall have a 28 days compressive of [__] MPa ([______] psi).
3. Concrete Materials
The concrete materials for reinforced concrete pipe shall be as follows:
a. Portland cement shall conform to the requirements of ASTM C 150.
b. The fine aggregates shall consist of sand, stone screening or other approved
inert materials with similar characteristics, or combination thereof, having a clean,
hard, strong, sound, durable and uncoated grains, free from injurious amounts of
dust, lumps, soft or flaky particles, shale, alkali, organic matter, loam or other
deleterious substances, and shall not contain more than three percent of materials
passing the 0.075 mm (No. 200) sieve by washing nor more than one percent of
clay lumps or one percent of shale. The use of beach sand is prohibited.
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Repair of Damaged Concrete Pavement at Open Storage
Area No. 2, Including Drainage System, Port of General Santos
Technical Specifications
Water, Sewer and Drainage System Including Wastewater Treatment Plant
The fine aggregates shall be tested for sodium sulphate soundness in accordance
with AASHTO T 104 five (5) cycles and shall show a maximum loss of not more
than 10 percent.
The fine aggregates shall be uniformly graded and when tested in accordance with
AASHTO T11 and AASHTO T27 shall meet the grading requirements shown below:
REQUIREMENTS FOR FINE AGGREGATE
US Standard
Sieve
mm
9.5
4.75
1.18
0.30
0.15
Alternative
(3/8 in)
(No. 4)
(No. 16)
(No. 50)
(No.
100)
Percent Passing by
Weight
%
100
95-100
45-80
10-30
2-10
Fine aggregates shall be such quality that mortar specimens, prepared with
standard Portland cement and tested in accordance with AASHTO T 71, shall
develop a compressive strength at 7 days of not less than 90 percent of the strength
developed by a mortar prepared in the same manner with the same cement and
graded sand having a fineness modulus of 2.40 � 0.10. Natural aggregates shall be
thoroughly and uniformly washed before use.
c. Water for curing, for washing aggregates and for mixing shall be subject to the
approval of the Engineer. It shall be free from oil and shall not contain more than
1,000 parts per million of chlorides as Cl, nor more than 1,300 parts per million of
sulphates as SO4. In no case shall the water contain an amount of impurities that
will cause a change in the setting time of Portland cement of more than 25 percent
nor a reduction in the compressive strength of mortar at 14 days of more than 5
percent when compared to the results obtained with distilled water.
d. When required by the Engineer, the quality of the mixing water shall be
determined by the Standard Method of Test for Quality of Water to be Used in
Concrete, AASHTO T26.
4. Reinforcement
Steel Bar Reinforcement for RC Pipes and RC Collar shall be deformed billet-steel bars
Grade 40, and with a minimum yield strength of [276 MPa], conforming to the requirements
specified in ASTM A 615 unless otherwise shown on the drawings or required by the
Engineer. The use of cold twisted bars is not permitted.
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Repair of Damaged Concrete Pavement at Open Storage
Area No. 2, Including Drainage System, Port of General Santos
Technical Specifications
Water, Sewer and Drainage System Including Wastewater Treatment Plant
5. Inspection before laying
All reinforced concrete pipes shall be approved by the Engineer prior to installation. Pipes
will be subject to rejection on failure to conform to any of the minimum requirements, and
units may also be rejected for reasons as follows:
a. Fractures or cracks passing the shell (except that which does not exceed the
depth of the joint).
b. Defects that indicate imperfect proportioning, mixing and moulding.
c. Damage indicating honeycomb or open texture.
d. Damage ends that prevent a satisfactory joint.
e. Warp or misalignment greater than 1 ½ percent of the true form; however, a wall
thickness greater than that specified will not be a cause for rejection.
6. Repair of pipes
Pipes may be repaired, if necessary, and will be acceptable if in the opinion of the
Engineer, the repairs are sound and properly finished and cured, and the repaired portion
otherwise conforms to the requirements of this Section.
6.3.2.2 MORTAR MATERIAL
1. Cement mortar shall consist of one part of Portland cement and two parts of fine
aggregates with water added as necessary to obtain the required consistency.
2. Portland cement, sand and water shall be in accordance with Section 3.2, "Concrete
Works."
6.3.2.3 POLYVINYL CHLORIDE (PVC) PIPE
Polyvinyl chloride (PVC) pipes for drain lines shall conform to ASTM D 1784, Class II.
Refer to Section 6.2, "Sanitary Sewer System" for the specification.
6.3.2.4 REINFORCED CONCRETE HEADWALL
Concrete and reinforcing bars shall be in accordance with Section 3.2, "Concrete Works."
Concrete shall have a 28 day compressive strength of [21] MPa ([3,000] psi)].
6.3.2.5 OPEN TRENCH (U-DITCH) WITH STEEL GRATINGS
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Repair of Damaged Concrete Pavement at Open Storage
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Technical Specifications
Water, Sewer and Drainage System Including Wastewater Treatment Plant
Excavation and backfilling works shall conform to the requirements of Section 4.2,
“Excavation and Backfilling for Building” of these specifications.
Concrete with steel reinforcement shall conform to the requirements of Section 3.2,
“Concrete Works” of these specifications.
Gravel bedding shall be of maximum size of 19mm conforming to the requirements of
Section 3.2, “Concrete Works.”
Steel gratings shall be pre-fabricated hot-dip galvanized structural steel forge
welded/machine made gratings and shall conform to the requirements of Section 4.6,
"Steel and Metal Works." Refer to the drawings for the details.
6.3.2.6 CONCRETE BEDDING
Concrete bedding when required by the Engineer shall have a 28-day minimum
compressive strength of [17] MPa ([2,500] psi)]. Concrete bedding materials such as
Portland cement, aggregates and water shall conform with requirements of Section 3.2,
"Concrete Works."
6.3.2.7 MANHOLES
1. Cement
Portland cement shall conform to the requirements of ASTM C 150 Type 1.
2. Fine Aggregate
Fine aggregate shall be in accordance with Section 3.2, “Concrete Works” and shall
conform with ASTM C 33.
3. Coarse Aggregate
The coarse aggregate shall consist of crushed or uncrushed stone, gravel or other
approved inert materials with similar characteristics, or a combination thereof, having
clean, hard, strong, sound, durable uncoated particles, free from injurious amount of soft,
friable, thin, elongated, or laminated pieces, alkali, organic or other deleterious matter and
conforming to the requirements of Section 3.2, "Concrete Works," of these Specifications
and ASTM C 33. The coarse aggregate shall be of uniform grading with maximum sizes of
19 mm.
4. Water
Water for washing, mixing and curing shall be in accordance with Section 3.2, "Concrete
Works."
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Repair of Damaged Concrete Pavement at Open Storage
Area No. 2, Including Drainage System, Port of General Santos
Technical Specifications
Water, Sewer and Drainage System Including Wastewater Treatment Plant
5. Steel Reinforcement
Steel reinforcement shall conform to the requirements of Section 3.2, "Concrete Works,"
and as shown on the drawings.
6. Concrete
Concrete for cast in place shall be Class C with 28 days compressive strength of [21] MPa
([3,000] psi)], unless otherwise indicated in the drawings or directed by the Engineer.
7. Gravel Base
Gravel base shall be of a maximum size of 19 mm conforming with the requirements of
Section 3.2, "Concrete Works."
8. Manhole Cover
Refer to Sub-section 6.3.2.5 for the material requirements of steel gratings.
6.3.2.8 BEDDING MATERIALS
1. Bedding where required shall conform to one of the classes specified. When no
bedding class is specified requirements for Class C bedding shall apply for concrete
pipe.
2. Class A bedding shall consist of a continuous concrete cradle conforming to
details on drawing.
3. Class B bedding shall consist of bedding with a depth of not less than 30 percent
of vertical outside diameter of pipe.
a. Minimum thickness of bedding beneath pipe shall be 100 mm.
b. Bedding material shall be sand or selected sandy soil all of which passes a
9.5 mm sieve and not more than 10 percent of which passes a 7.5 mm sieve.
c. Layer of bedding material shall be compacted and shaped to fit pipe for at
least 15 percent of its total height. Recesses in trench bottom shall be
shaped to accommodate bells or other projections.
4. Class C bedding shall consist of bedding with a depth of not less than 10 percent
of its total height with foundation surface shaped to pipe contour.
6.3.3 EXECUTION
6.3.3.1 EXCAVATION
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Area No. 2, Including Drainage System, Port of General Santos
Technical Specifications
Water, Sewer and Drainage System Including Wastewater Treatment Plant
1. A trench shall be excavated to the line, depth and grade necessary for the pipe to
be laid as shown on the drawings. Except where bedding is required, the bottom of
the trench shall be shaped to conform to the shape of the pipe for at least 30
percent of its outside circumference. The width of the trench shall be as shown on
the drawings but not be greater than 2 times the pipe diameter, to permit
satisfactory jointing and thorough tamping of the bedding material under and around
the pipe.
2. All soft unsound material underlying the proposed pipework shall be removed to
the depth required by the Engineer and shall be replaced by suitable material in
layers not exceeding 200 mm in depth and compacted.
6.3.3.2 BEDDING
The trench shall be excavated to the depth required for the gravel or sand bedding as
shown on the drawings and in accordance with Section 4.2, “Excavation and Backfilling for
Building.”
Soft, spongy, or otherwise unstable materials encountered that will not provide a firm
foundation for the pipe shall be removed for the full width of the trench and replaced to a
depth of not less than 30 percent of the vertical outside diameter of the pipe.
After excavating, gravel or sand bedding shall be laid to the dimensions shown on the
drawings or as may be directed by the Engineer.
Bedding, unless shown otherwise in the drawings, shall be provided for depth of not less
than 10 percent of total length of pipe; with sufficient additional bedding placed and shaped
to pipe profile to provide continuous support for not less than 25 percent of pipe
circumference.
Proportioning, mixing, placing and using concrete bedding shall be in accordance with
Section 3.2, "Concrete Works."
6.3.3.3 PLACING RC PIPE
1. Pipe trenches shall be inspected and approved by the Engineer prior to start of
work. RC collar and grout joints shall be properly cured, dried and approved by the
Engineer prior to start of backfilling.
2. The pipe shall be laid carefully with bells at the higher end and with ends fully and
closely jointed, and true to the elevations and grades given. Proper facilities shall be
provided for lowering the sections when they are to be placed in a trench.
3. Pipe shall not be installed when subgrade material is in muddy or soggy
condition.
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Repair of Damaged Concrete Pavement at Open Storage
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Technical Specifications
Water, Sewer and Drainage System Including Wastewater Treatment Plant
4. Under no circumstances shall pipe be laid in water, and no pipe shall be laid
when the trench conditions or the weather are unsuitable for such work, except with
specific approval of the Engineer.
5. Any pipe which is not in true alignment or which shown any undue settlement
after being laid, or is damaged, shall be taken out and relaid or replaced without
additional cost to the Employer.
6. Tongues shall be adjusted in grooves to give a uniform space all around.
Blocking or wedging between tongues and grooves shall not be permitted. Pipe that
does not allow sufficient space for proper caulking and installation of jointing
material shall be replaced by one of the proper dimensions. Open side of pipes at
the end of each day's work shall be closed temporarily with wood blocks or
bulkheads.
7. The first unit shall be properly bedded. A shallow excavation for the concrete
saddle with dimensions as shown on the drawings, shall be made underneath the
unit at the joint and filled with mortar to provide a bed for the second. The mortar
shall consist of 1 part Portland cement to two parts of clean sand by volume with
sufficient water to obtain the workability required. The grooved end of the first unit
shall be carefully cleaned with a wet brush, and a layer of soft mortar shall be
applied to the lower half of the groove.
The tongue of the second pipe shall be cleaned carefully with a wet brush, and
while in a horizontal position, a layer of soft mortar shall be applied to the end of the
first, until mortar is squeezed out on the interior and exterior surfaces. Sufficient
mortar shall be used to completely fill the joint and to form a collar on the outside
(refer to the drawings for the construction of RC collar). The interior surface of the
units at the joint shall then be brushed smooth. The collar on the outside shall
immediately be protected from the air and sun with a cover of wet burlap or wet
earth, and shall be kept protected until the mortar is satisfactorily cured.
8. Movement of any construction equipment or machinery over any drain shall be at
the Contractor's risk, and any damage resulting from such operations shall be
repaired, as directed at the Contractor's expense.
9. No pipeline shall be placed in service for which it is intended until terminal end is
provided with suitable structure or outlet; and until approved and ready for service.
The upper end shall be maintained plugged or blocked against entry of any water.
6.3.3.4 CONSTRUCTION OF DRAINAGE SYSTEM
1. Formworks
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Repair of Damaged Concrete Pavement at Open Storage
Area No. 2, Including Drainage System, Port of General Santos
Technical Specifications
Water, Sewer and Drainage System Including Wastewater Treatment Plant
Formwork shall be supplied and fixed in the position as required by the concrete to be cast
as shown in the drawings or required by the Engineer and shall be supplied, erected and
removed as specified in Section 3.2, "Concrete Works."
2. Concrete
Proportioning, mixing, placing and curing of concrete shall be in accordance with Section
3.2, "Concrete Works." Steel reinforcement and steel for grating shall be furnished, bent
and fixed in accordance with Section 3.2, “Concrete Works” and where shown in the
drawings.
3. Connections
Sections of connections pipes shall be incorporated into the construction of the manholes,
catch basins and outlet structures and placed at the elevation, direction and grade
structure and placed at the elevation, direction and grade required. The inner ends of the
pipe shall be flush with the inner face of the walls in manholes and outside face of the wall
in case of outlet structures.
4. Cleaning
Upon completion, each manhole, catch basin and outlet structure shall be thoroughly
cleaned of any accumulation of silt, debris, or other foreign matter of any kind and shall be
kept clean of such accumulation until final acceptance of the work.
6.3.3.5 BACKFILLING
1. After the pipe has been installed and the mortar joints sufficiently set, selected suitable
material shall be placed alongside the pipes in layers not exceeding 200 mm in depth and
compacted so that on each side of the pipe there shall be thoroughly compacted material
of the same height. This method of filling and compacting shall be continued until the fill
has reached an elevation of 300 mm above the top of the pipe.
2. Backfilling for manhole and concrete lined drains shall be in accordance with Section
4.2, “Excavation and Backfilling for Buildings.”
6.3.4 MEASUREMENT AND PAYMENT
1. The quantities to be paid for, for each class and diameter of drainage pipe, shall
be the length of pipe between the outside faces of the end walls, measured along
the axis of the pipe as shown on the drawings or ordered, installed in placed,
completed and certified for payment by the Engineer. The excavation of trenches,
and backfilling, shall be measured for direct payment in accordance with Section
4.2, “Excavation and Backfilling for Buildings.”
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Repair of Damaged Concrete Pavement at Open Storage
Area No. 2, Including Drainage System, Port of General Santos
Technical Specifications
Water, Sewer and Drainage System Including Wastewater Treatment Plant
2. The manholes to be paid for shall be the number of concrete manholes complete
with covers and other relevant components in place, accepted and certified for
payment by the Engineer. Separate pay items shall be provided for the different
types of manholes as shown in the Bill of Quantities. Payment shall include
concrete walk, formwork, reinforcement, gravel bedding, and other incidental
necessary to complete the work.
Granular material in bed of manhole shall be measured by volume in cubic meters
of material furnished, installed and compacted and certified for payment by the
Engineer.
3. The outlets to be paid for shall be the number of outlet structures which consist of
the RC wall and RC pipe base, completed and certified for payment by the
Engineer. Separate pay items shall be provided for different sizes of outlet
structures. Payment shall include furnishing of all materials, labor, equipment and
other incidentals necessary for the complete construction of the outlet structures.
Payment shall be full compensation for all concrete, reinforcement and all other
work necessary to complete each type of outlet structure.
4. Both formwork and reinforcing steel bar will not be paid separately, cost shall be
deemed included in the payment for concrete, manholes or outlet structures.
5. All earthworks (excavation and backfilling) for the laying of drainage pipe,
manhole, outlet headwall, and u-drain shall be paid separately in accordance with
Section 4.2, “Excavation and Backfilling for Buildings.”
6. The quantity of concrete and reinforcement works for concrete u-drain to be paid
for shall be measured in accordance with Section 3.2, Concrete Works. Separate
pay item shall be provided for the supply and installation of steel gratings including
steel frame which shall be paid for by the length in linear meters installed to include
all incidental necessary to complete the work.
The quantity of reinforced concrete drainage ditch inside the wet market shall be
measured by the length in linear meters of R.C. drainage ditch constructed to
include reinforced concrete, steel gratings and all incidental necessary to complete
the work.
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Repair of Damaged Concrete Pavement at Open Storage
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