Drain Laying (BS EN 1610:2015)
Construction and
Testing
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Drain Laying
The bottom of a drain trench must be
excavated to a gradient.
This is achieved by setting up sight rails.
A boning rod (like a long 'T' square) is
sighted between the rails to establish the
level and gradient of the trench bottom.
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Test on Drains
A drain must be tested for leakage before and
after backfilling trenches.
Three important tests are:
1. Air Test
2. Smoke test
3. Water test
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Air Test
The drain is sealed between access chambers
And pressure tested to 100mm water gauge
with hand bellows and a 'U' gauge
(manometer).
The pressure must not fall below 75mm
during the first 5 minutes.
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Air Test
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Smoke Test
The length of drain to be tested is sealed, and
smoke pumped into the pipes from the lower
end.
The pipes should then be inspected for any
trace of smoke.
The smoke machine can be used on clay and
concrete pipes; they may be applied directly to
the pipeline.
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Smoke Test
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Water test
The lower part of the drain is stopped then
filled the upper end with water.
A purpose-made test bend with an extension
pipe to produce a 1.5m head of water is
required.
2 hours limit for porosity is also required.
30 minutes afterwards, maximum leakage for
100mm and 150mm pipes should be 0.05 and
0.08 litres per metre run, respectively.
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Water Test
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Means of Access, Gh Regulation 122
Drain access may be obtained through:
Rodding points
Shallow access chambers
Inspection chambers
And Manholes.
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Functional Access Requirements
Pipe runs should be straight, and access
should be provided only where needed, i.e.
At significant changes in direction
At significant changes in gradient
Near to, or at the head of a drain
Where the drain changes in size
At junctions
On long straight runs.
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Shallow Access Chamber
They are small
compartments
used as rodding
points
It provides drain
access in both
directions and
possibly into a
branch.
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Inspection Chamber
Inspection chambers are larger than access
chambers.
It has an open channel and space for several
branches.
Can be circular or rectangular on plan
They are made from uPVC, precast in concrete
or bricks from a concrete base.
It provides surface access only; therefore, the
depth to the invert level does not exceed 1m.
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uPVC Inspection Chamber
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Precast concrete Inspection
Chamber
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Brick Inspection Chamber
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Manhole
Manhole is used generally to describe drain
and sewer access.
Manholes are large chambers with sufficient
space for a person to gain access at the drain
level.
Where the depth to invert exceeds 1m, step
irons should be provided at 300mm vertical
and horizontal spacing.
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