SCOPE OF WORK
The work specified in this section covers
design and supply of all labor, materials, transportation, equipment and
services, installation or construction and testing the following works as
indicated in Book IIIA, Section 4.4.1
Technical Specification refers to "General Civil & Architectural
Design Requirements".
Sewage and storm drainage work including
but not limited to ditches, piping, manholes, culverts etc.
Duct work for electrical
cables and pipes.
The requirements for the
excavation and the concrete work are covered in Book IIIA, Technical
Specifications refer to "Earth Works" and refers to "Concrete
Work" respectively.
CODES AND STANDARDS
The Contractor shall
comply with the requirements of Book II refers to "Codes and
Standards".
The Codes and Standards
of the following organizations extracted form Book II refers to "Codes and
Standards" are specifically applicable to the design of the work included
in this Specification:
AASHTO American Association of State Highway
and Transportation Officials.
ASTM American Society for
Testing and Materials.
CONCRETE PAVED DITCHES
Concrete paved ditches
shall be constructed according to the approved drawings and at the locations
shown thereon, or as directed by the Owner. Construction of the paved ditches
and cutoff wails shall be in conformance with lines, grades and dimensions
designed by the Contractor and approved by the Owner. The concrete shall have a
minimum compressive strength of 225 kg/cm2 conforming to the requirements
of Technical Specification refers to "Concrete Work".
The
cement and sand used shall meet the requirements as specified in Technical
Specification refers
to "Concrete Work".
STORM SEWERS AND CULVERTS
Drainage culverts, storm
sewers and paved ditches shall be one of the following type as specified, or as
indicated on the approved drawings.
STORM
SEWER
Storm sewer sections
shall be rectangular concrete paved ditches with the minimum width of 30 cm.
Concrete
paved ditches shall be constructed according to the details on the approved
drawings and at the locations shown thereon, or as directed by the Owner.
Construction of the paved ditches and cutoff walls shall be in conformance with
lines, grades and dimensions shown on the approved drawings.
REINFORCED
CONCRETE DRAINAGE PIPING
Pipe and
Fittings : Reinforced
concrete, confirming to the applicable requirements of ASTM C76, Class IV or
approved equal.
Size : As indicated on the approved drawings
Markings : Each length of pipe shall be clearly
marked with name of manufacturer, location of plant where made, date of
manufacture and pipe class.
Joints : The Contractor shall provide all
materials required to
complete
the work and shall install rubber gasket and joint material between the joints
of concrete pipe sections in strict accordance with the manufacturer's
instructions.
Coating : not
required.
Concrete
pipe shall not be backfield until inspected and approved by the Owner.
CULVERT
Culverts shall be reinforced concrete and
if located under roads they shall be designed to withstand an HS20‑44 loading.
Expansion joint shall be provided for the culverts having more than 15 m length
and for expansion joints, the water stops as specified in Technical
Specification refers to "Concrete Work" shall be used.
MANHOLES
Construct manholes of
precast concrete, complete with cast iron frames and covers, steps etc. herein
specified.
Precast
Concrete Manholes
Type:
Precast reinforced concrete ring type with precast reinforced concrete base and
rubber "O‑ring" or flat type rubber compression joints, conforming to
applicable requirements of ASTM C478, "Specifications for Precast
Reinforced Concrete Manhole Risers and Top" and to requirements herein
specified or approved equal.
Loading
Design manholes for HS20‑44 truck loading.
Precast
Elements
a.
Base
closed end pipe type with bell end.
b.
Ring
sections for walls: Provide in multiples of 200 mm in height, with tongue and
groove joints as required by depth of each manhole. The wall thickness for
rings shall be 100 mm for 900 mm diameter manholes, 125 mm for 1200 mm diameter
manholes and 150 mm for 1800 mm diameter manholes.
c.
Top
section shall be the eccentric cone type with a minimum wall thickness of 100
mm for 900 mm diameter manholes, 125 mm for 1200 mm diameter manholes and 150
mm for 1650 mm diameter manholes, or shall b6 the flat slab type not less than
200 mm thick, as required by manhole depth.
Arrange
both types for use with a cast iron manhole frame and cover.
d. The rings and top cone shall have precast
openings for field installation of cast iron steps and for all required
drainpipes entering manholes.
Joints:
Rubber "O‑ring" of flat type rubber compression type, with
manufacturer's standard rubber ring. Mortar joints may be used only per Owner's
approval.
Frames,
Covers and Steps
Cast
iron as indicated on the approved drawings.
Coating:
Coat uniformly with coal tar pitch varnish.
Type:
As indicated on the approved drawings.
Installation
of Manholes
Subgrade
shall be level and free of projecting stones, rocks etc.
Place a
layer of sand, not less than 100 mm thick, over the subgrade before installing
the precast base. Exercise care in installing the base level with full bearing
throughout on the sand cushion to insure that the completed catch manhole is
plumb.
Install sections, using rubber rings, in strict
accordance with manufacturer's instructions, or as approved by the Owner.
CABLE DUCT, TUNNEL AND PIPE TRENCH
All reinforced concrete ducts;
tunnels and trenches shall be constructed in accordance with the approved
drawings.
The ducts and trenches shall be
poured in place reinforced concrete construction. All ducts and trenches shall
be covered with removable trench covers. All trenches shall be drained. Pumps
if required for draining, shall be automatic permanent type.
The covers shall be precast
reinforced concrete and shall have a smooth and even upper surface, be square
in shape, free from cracks and from damage to edges.
At all changes in direction,
thrust blocks having a minimum volume of 0.20 m3 per pipe or
larger as required by design shall be provided and shall be cast in situ,
centered on the bisector of the bend angle.
Sectional steel for support of
covers shall be embedded in concrete. It shall be thoroughly set in line and
level and duly fixed to the form and/or maintained as to avoid any displacement
during pouring. Tolerance of setting (distance between vertical flanges) shall
be + 0.5 cm (5mm) and ‑ 0.00.
Draw pit shall be provided in
duct not exceeding 8 m in length.
The ends of non-continuous cable
or pipe ducts shall be temporarily sealed to prevent the ingress of backfill
material.
In reinforced concrete cable ducts, the
reinforcement shall be installed as not to form a closed loop around the ducts.
Individual reinforcement bars,
which would form part of closed loop, shall be electrically insulated from each
other in order to break the loop.
Tunnels shall be cast in place
reinforced concrete completed with manholes, ladders, drain pits, automatic
permanent pump and drainage ditch. Manholes shall be provided at every 100 m
distance and at change of direction. Minimum height of tunnel shall be 1.75 m
and minimum width shall be 2 m. Mechanical ventilation shall be provided in the
cable tunnel.
Expansion joint shall be
provided at every 50 m distance, at every junction and at charge of direction
of ducts, tunnels and trenches.
Unless otherwise required, all
steel embedded in concrete shall be galvanized.