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HDPE PIPE LAYING

1. Trench

The trench should be nanow, but not less than 40 cm

(16 inches) wide and should be checked for depth and slope'

The bottom of trench must be even and stonefree.

2. Bedding

ln normal soil the bedding should be of sand or gravel and 15

r'cm (6 inches) thick. Stones in the graUel:must not be bigger

than 20 mm. (415 inches). It is not necessary to compact the

bedding.

3. Bottom supporting

When pipe is laid clearances are allowed for sockets and

flanges so that the pipe is supported along its whole iength.

The bottom supporting is compacted as shown in the diagram.

It is important that the supporting is finn and even along whole

length of pipe, otherwse the pipe could be darnaged. lf more

than one pipe is being iaid in the trench the initial backfill for

the lower pipes must be compacted 6efore the next layer of

pipes is laid.Check the pipe for slope and alignment.

The simplicity of laying pipes made fronr- HDPE

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4-lnitial_ Bagkfill

The initial backfill should be made in 10 cm (4 inches) thick

layers using sand or gravel and compacted as illustrated in the

diagram. lf a machine is used for compacting it should be light

and easy to handle and care should be taken that the machine

does not contact the top of the pipe.Compact to a 90% Proctor

density. lt is this initial backfill that supports the pipe and

protects if from deformation so that compacting must be carried

out carefully by tamping on each side of the pipe altemately. lt

is important that gravel size should.not be greater than 20 mm.

(4/5 inches)diameter.

5, Prp.tecjive Fl|Jir.rg

.. Use the same s' described'for the initial backfill.,'B-

It is essential that thbre are no large stones in this fill as they

can cause point stresses on the pipe and damage it. protective

filling should be 30 cm. (t foot) thick and tamping with a heavy

machine on top of the pipe should be avoided. lf ground water

flows into the trench during ihis operation increase the speed of

filling or the or the pipe wilt ftoat

6. Final. Backfill

complete the filling of the temch with the excavated materiar

evenly distributing the stones through out ihe fill. compact to

minimum of g0% Proclor density. Foilow the recommended

building instructions. The pipelaid will need a minimum of

maintenance.

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