Foul drain laid in rock

[Triassic]

I’ve had the basement dug out into a hillside and I’ve just started levelling  ready to install the insulated raft foundation. Before I do that, I need to install a foul drain to serve a bathroom, along with a spur to the storeroom containing  the thermal store. The problem I have is that we hit limestone  bedrock, so I’ll need to chisel out a slot around 20m long into which the Darin will go. What is the minimum depth the Building Inspector is likely to find acceptable?

[ToughButterCup]

3 minutes ago, Triassic said:

[..]

. The problem I have is that we hit limestone  bedrock, so I’ll need to chisel out a slot around 20m long into which the Darin will go. 

[...]

 

Oooooooooofffffff 

[PeterW]

50mm bed of pea gravel is fine 

[Ian]

33 minutes ago, Triassic said:

What is the minimum depth the Building Inspector is likely to find acceptable?

There's no minimum depth as far as I know however you'd need to check with your BCO. If it's very shallow they may want you to surround the drain in concrete with movement joints at each pipe joint

[MikeSharp01]

I have a friend with an explosives licence - she might be able to 'create' a feature in which to run the pipe!

[Triassic]

Just to clarify, the ground surface is limestone bedrock, how deep into the rock would I need to dig ?

[PeterW]

If you are less than 200mm below the surface to the top of the pipe, from memory I think you need to encase in concrete.

 

http://www.marleyplumbinganddrainage.com/media/5423/pipe-laying.pdf

[Triassic]

Had a helpful conversation with our Building Control guy, he’s happy with 50mm of concrete cover over the pipe encased in rock.

[Triassic]

Just one further question. I was thinking of running a drain from my thermal store to the sewer 12 metres away. Is this OK run in 40mm waste pipe, is 40mm big enough?

Edited March 8, 2018 by Triassic