Underground drainage advice

[RomanAbramovich]

Have a 450mm plastic inspection chamber to install - does this need to sit on pea gravel, as per plastic pipes or should it be bedded onto concrete?

Also, what is the exact spec for bedding/back filling plastic underground drainage pipes in a trench - 100mm pea gravel bed, infill either side of pipe with pea gravel then infill 100mm on top of pea gravel, final layer of infill being spoil from excavated trench?

 

[noseall]

Have a 450mm plastic inspection chamber to install - does this need to sit on pea gravel, as per plastic pipes or should it be bedded onto concrete?

Bedded in concrete. We usually set the chamber bottom, install the pipes then ram concrete into the voids, taking care not to obstruct any inlets/outlets.

Also, what is the exact spec for bedding/back filling plastic underground drainage pipes in a trench - 100mm pea gravel bed, infill either side of pipe with pea gravel then infill 100mm on top of pea gravel, final layer of infill being spoil from excavated trench?

Lay your pipes, pack if necessary then chuck in the pea gravel. Be careful not to ram the pea gravel under he pipes as you may inadvertently lift them. It's a right faff trying to reset them once you have done this! A bit of gentle prodding is all you will need.

 

[RomanAbramovich]

Do BCO's expect to see the underground drainage scheme with pipes connected to the chamber bottom only, or should I do the base concrete and fit the risers before making the call for an inspection?

 

[noseall]

Do BCO's expect to see the underground drainage scheme with pipes connected to the chamber bottom only, or should I do the base concrete and fit the risers before making the call for an inspection?

They are not particularly interested in seeing the risers, but I would deffo do the concrete thing.

Only half submerge the pipe runs in pea gravel so that they can observe all the connections etc.