SECTION – 2 –A SEWERAGE/ DRAINAGE WORK - uPVC

2.1 DESCRIPTION
2.1.1 Sewerage Pipes

All sewerage/drainage pipe work inside the houses and buildings and upto the connection to the trunk sewer
shall be covered under this section. The pipes shall be UPVC as specified including soil, waste, vent and anti-
syphonic pipes.

2.2 MATERIAL REQUIREEMNTS

UPVC Soil and Waste etc piping shall conform to BS EN 1329-1 2000 marked as BD or other equivalent
specifications with solvent cement or rubber ring joints as specified.

Where required UPVC pipes conforming to the specifications ISO 3633/ PS 3214/ BS-3505/ ASTM D-1785 i/c
fitting and as specified in this section may be used in outside underground conditions.

2.3 SOIL, WASTE, VENT AND ANTI-SYPHONIC PIPES

The pipes shall run exposed or embedded in wall and floors as specified or shown on drawings. Where
embedding in walls or floors is required, the necessary instruction and route of pope work shall be approved by
the Engineer. Pipes running exposed on walls and ceiling shall be properly clamped with Hangers, supports and
clamps for passage of popes through masonry wall and RCC beams, slab and walls, pipe sleeves shall be
embedded and properly caulked and water proofed.
Horizontal soil and waste pipes unless otherwise specified shall be given a grade of 6.4 mm (1/4”) and 3.2 mm
(1/3” 1/ft. respectively. All main vertical soil stackes shall extend full size to above the roof line, except where
otherwise indicated. The part of the soil stacks carried up as vent pipe shall not have any bend or angle except
when unavoidable, in which case, the angel shall be as abuse as possible. The vent stack shall joint the soil
stack at a point not less than 3 feet (900 mm) above the highest connection to the soil stack. Horizontal waste
lines receiving the discharge from two or more fixtures on the first floor shall be provided with end vents, unless
separate venting of fixtures is called for.
Changes in pipe size on soil, waste and drain lines shall be made with reducing fittings or recessed reducers.
All changes in direction shall be made by the appropriate use of 45 degree Wyes, long or short sweep 3 mm to
1.5 mm bends etc. or equivalent fittings as approved. Single and double sanitary tees and quarter bends may
be used in drainage lines only where the direction of flow is from horizontal to vertical. Short sweep not less
than 75 mm (3”) in diameter may be used where the change in direction of flow is either in plan or vertical to
horizontal and may be used for making necessary offsets between the ceiling and the next floor above. The use
of short sweep bends or fittings, where deemed necessary because of installation conditions, shall be subject to
the approval of the Engineer.
Contractor shall provide offsets in the pipit where required or directed by the Engineer to avoid interference with
other work, or to increase the headroom under piping, or to improve the appearance of the pipe work. Piping
shall be installed in such a manner that will permit freedom of movement during expansion and contraction
without causing the pipes to be warped and adequately insulated against noise transmission through pipe work
in habitable rooms.
All piping shall be installed in such a manner as to prevent delay or interference with the work of others working
in the same area. All openings I pipes shall be kept closed during construction working in the same plugs.
Slip joints shall be permitted only in trap seals or on the inlet side of the traps. Tucker or hub drainage fittings
shall be used for mating union connections wherever practicable.
The use of long screws and bushing is prohibited.
Clean-out shall be of the same size as the pipe except that clan-out plugs larger than 100 mm (4”) will not be
required. Clean-out installed in connection with spigot and socket pipe shall consist of long sweep 1/4" bend or
one or two 1/8” bends extended to any easily accessible place, or where indicated on the drawings. An extra
heavy cast-brass ferrule or as specified with outer sunk trap screw cover shall be caulked into the hub of the
fitting and shall be flush with the floor. In addition, clean-outs shall be provided at all changes of direction in
excess of 45 degree, and at distance not exceeding 15 meter (50 feet) in horizontal drain lines larger than 100
mm (4”). Underground clean-outs shall be extended to an accessible location, to the surface of the floor above,
or to grade, subject to approval of the Engineer. Panels and plates for access to clean-outs shall be provided.
Each fixture and piece of equipment, including floor drain, requiring connections to the drainage system shall be
equipped with a trap. Traps are to be supplied with the fixtures. Each trap shall be placed as near to the fixtures
as possible, and no fixture shall be double-trapped.

2.4 TESTING OF PIPELINES

No work shall be covered over or surrounded with concrete until it has been inspected, tested and approved by
the Engineer.

2.5 INSPECTION AND TESTING OF DESCHARGE PIPES

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Work should be inspected and tested during installation, care being taken that all work which is to be concealed
is tested before it is finally enclosed. Final tests should be applied on completion of the installation both for
soundness and performance. Normally, the air test is used for soundness, but if the water test is applied, it
should be used only upto the level of the lowest sanitary appliance connected to the system and then only in
new system.
When testing old systems, it may by necessary to limit the pressure applied because of shallow trap seals; the
water test should not be used. Any defects revealed by the test should be made good and the test repeated
until a satisfactory result is obtained.
Reference should be made to Local Authority and other enforcing authority requirements, particularly where
pipe work passes through areas where blockages and leaks cannot be detected. In general, sufficient access
should be provided to enable complete systems to be tested.
Access points should be carefully sited to allow the entry of cleaning and testing equipment and consideration
also be given to adjacent services. Traps and joints that are easily disconnected can be an advantage so
additional access is required only under exceptional circumstances.
The discharge from urinals can give rise to heavy deposits, especially in hard water areas. Regular
maintenance is therefore required and access should be provided so that all pats of the stack, branch,
discharge pipe and trap can be readily cleaned. Where the vertical discharge pipe had a long connection to a
manhole, access should be provided at ground floor near the foot of the stack.
In multi-storey domestic buildings, access should be provided at 3 storey intervals or less. In public and
commercial buildings and more complex, drainage systems, access should be provided at each floor level.
The discharge from appliance produces pressure fluctuations and the system must be designed to retain
adequate water seal in all traps under excessive working conditions. Pressure effects that occur may be due to
self siphon age or positive pressure. It may be necessary to use a ventilating pipe to limit the pressure
fluctuations in the system within the acceptable limits.
The effect of the flow of water from an appliance into a branch discharge pipe must be considered taking
account of:

a) The design of the appliance (funnel shaped appliances increase the possibility of self siphon age)
b) The length, slope and diameter of the branch discharge pipe.
Seal losses produced by effluent flow down the discharge stack depend on:
a) The flow load which in turn depends on the number of appliances connected and frequency of
use.
b) The diameter of the discharge stack.

Air Test

An air test should apply a pressure equal to 3.8 mbar (38 mm) (50 mbar (50 mm) Scotland) water gauge and
should remain constant for a period of not less that three minutes (five minutes Scotland). The water seals of all
sanitary appliances which are installed should be fully charged and a test plug inserted into open ends of the
pipe work to be tested, each plug being sealed with a small quantity of water. One testing plug should be fitted
with a tee-piece, with a cock on each branch, one branch being connected by a flexible tube to a manometer.
To apply the test, air or smoke is introduced into the system through the other branch of the tee-pipes until the
desired pressure is shown on the manometer scale. Alternatively, the pressure may be applied by passing a
flexible tube from a tee-pipes attached to a manometer through the water seal of the trap of a sanitary
appliance, the test then being carried out as previously described.
Defects revealed by an air test may be located by the following:
a) A smoke producing machine may be used which will introduce smoke under pressure into the defective
pipe work. Leakage can be observed as the smoke escapes.
b) Soap solution can be applied to the pipes and joints, under test, leakage can be detected by the
formation of Bobbies.

Performance of Testing Systems

In addition to test for air or water-tightness, every discharge pipe installation should be tested for stability of the
trap seals on the system. When subjected to the appropriate discharge tests, every trap must retain not less
than 25 mm of water seal. Each test should be repeated three times, traps being recharged before each test
and the maximum loss of seal in any one test should be taken as the significant result.
The number of appliances to be discharged simultaneously for the test depends upon the number of appliance
installed an the use and occupancy of the building. Suitable figures are given in Table C9 for dwellings. For
other types of buildings e.g. hotels and hospitals, the service conditions lie somewhere between these two. The
number of appliances to be discharged simultaneously to simulate these conditions should be estimated from
the figures given in Table C9 the expected service conditions.

Dwellings

To test for the effect of self siphonage, waste appliances should be filled to over flowing level and discharged I
the normally way. The seal remaining in the trap should be measured when the discharge is finished.

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 To test for the effects of probable maximum simultaneous discharges of sanitary appliances, the number of
appliances to be discharged together is given in Table C9. For the purpose of this test, baths are ignored as
their use is spread over a period and they do not normally add materially to the peak flow.
Where a stack services baths only, the number to be discharged simultaneously in a test should be the same as
for sinks. The wors5t conditions occur when appliances on the upper floors are discharged. A reasonable test
therefore is to discharge up to one WC, one basin and one sink from the top floor of the building with any other
appliances to be discharged on the floor immediately below.

Table : C9 Number of appliances to be discharged simultaneously for testing g stability of seals;

Number of
appliances Number of appliances
of each kind WC discharged simultaneously Kitchen
on the stack 9 litres Wash Basin Sink

1-9 1 1 1
10-24 1 1 2
25-35 1 2 3
36-50 2 2 3
51-65 2 2 4

2.6 MEASUREMENT

All pipe work shall be measured in running foot / meter of finished length. No wastage or length consumed in
joints shall be measured for payment. Bend, Tee, Sockets, spigot and collars etc shall not be measured
separately.

2.7 RATE AND PAYMENT

The rate for all items under this section shall cover the cost of all materials, labour, tools, equipment and
appliance and performing all operations for laying, fixing and jointing and all weak as specified in accordance
with drawings, bill of Quantities and as directed by the Engineer. Rate for pipe work shall also include making
and repairing cut holes and chases in wall, floors and slabs etc. painting pipes, supports and accessories
cleaning and clearing pipe lines and testing till approved by the Engineer.

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