Inspection Chamber Install/Backfilling

[BadgerBadger]

About to get stuck into our drainage system and have a number of plastic 450 inspection chambers to install.

 

What's the consensus on what to use to install and backfill around them please?

 

I seem to have found everything from fully surrounding them with concrete, to just sitting them on a bit of pea gravel and putting the dug material back.

 

I have a couple in driveway, a couple in patio, and others in soft landscaping.

[Jenki]

For the driveways I'd be tempted to put them on a firm base, possibly concrete but only to the base level, or a flag stone.  I would back fill all of them with pea gravel, or where I am quarry dust. If you ever need to dig them up you'll regret throwing in random stones.

Make sure you get your levels and falls sorted. The main flow should enter the bottom of the channels, as the branches are usually higher. 

[saveasteading]

Technically these are formers for concrete. Anything else is a cheaper, inferior variation. 

I've used all variations acc to purpose and situation.

[eandg]

We covered pipework with pea gravel and then backfilled with what had been dug out. 

[crispy_wafer]

When I did/redid what the builder did on mine…. I sat mine on a concrete mix so it held level, then surrounded the chamber in pea gravel, pipes were supported on, and all around and above with pea, then covered with crusher run concrete, or pea then excavated material depending on where the pipe was (garden, or patio).

[crooksey]

Dig out, mix 6:1 dry mix about 1ft deep, compact and sit chamber on this, backfill around sides and pipes with pea gravel.

 

Rent a tench whacker and whack all out pipe trenches before laying pipes, as a first timer its easy to dig the trench "too much" and then lay new pipes on loose ground, whacking the trenches before laying shingle and pipe is paramount to stop future failure. 

 

Fill a good amount above the pipe with gravel, if the ground does/drop settle this gravel will drop down and fill the voids, same principle for below the pipe in the event of clay heave etc.