Drainage - Building on an inspection chamber

[Twells]

Hi, I've scoured the internet for a solution to this problem and there are plenty of 'similar' queries but none that I can see which cover this one.

I am hoping to build a single storey extension at the rear of our house - the full width of the house is approx. 7m. We are an end terrace and are planning to build upto the boundary with our joining neighbour. Unfortunately,we have an inspection chamber right where we have to build the wall. I'm certain it is rain water drain and I know it is approx. 1.5m deep to the invert - there is another IC on this run approx. 7m away on our other boundary. I have spoken to the LA who have confirmed there are no public drains or sewers in our rear garden so permissions from utilities are not needed - we are responsible for our own drains/sewers in our road.
While Im comfortable with building a 'bridge' across the drain pipe itself for the cavity walls to sit on the other boundary, I'm less certain about how to treat an actual IC and building a wall on it. Clearly, building a wall on it will render it useless for inspections but my queries are:
1. Can we cap off the IC and build on it given there is another IC only 7m away?
2. If so, how would we go about it?

To clarify, both ICs are brick construction.

Any guidance on this would be much appreciated.
Cheers

Twells

[lutonlagerlout]

twells
good job you asked first

this situation arises all the time and bob the bodger says cap it off and forget

over the next 2-3 years rats realise the IC is now a lovely hang out and then start investigating pipes that are no longer in use

eventually they gnaw their way into your underfloor and from then up through the house

and that is when we get the call from drain domain our resident rat man

correct way

firstly you need to make sure that any pipes that will be unused after the build are correctly capped off in the IC

I dont care if you need a sink till the last day of the build if you leave it they will come

secondly make sure all live runs are roddable

then if it has to be capped keep the cap as low as possible and make sure it is substantial

i.e 68 mm concrete slab well bedded on and covered in concrete

follow this advice for a rodent free future

cheers LLL

[sy76uk]

You also need to be sure that the IC'S purpose isn't because there is a change in direction.

[seanandruby]

You also need to be sure that the IC'S purpose isn't because there is a change in direction.

or gradient.

[rxbren]

if it is only storm/surface water it might be possible to completely scrub the chamber out, run a new pipe to the outside of the extension (falling from outside of extension to where it connects to the downhill side of the old ic) the new pipe replaces the old ic so just y the other pipes into it.
If the ic was for a change of direction and it is only storm water as long as there is a rodding eye uphill building control will pass it.

[Twells]

Thanks everyone, your comments are really helpful (lutonlagerlout, sy76uk, seanandruby, rxbren). I was a touch concerned that something like this might render the whole project unviable but sounds like its not insurmountable - and more importantly it will be possible to satisfy building control.

Just for clarification, there is no change of direction and its a straight run from the other IC 7m away (which is a junction IC with 3 feeds). Also, the drainpipe run would still be operational after the build - we just need to build a wall over the IC capping.

Thanks again
TWELLS

[Twells]

twells
good job you asked first

this situation arises all the time and bob the bodger says cap it off and forget

over the next 2-3 years rats realise the IC is now a lovely hang out and then start investigating pipes that are no longer in use

eventually they gnaw their way into your underfloor and from then up through the house

and that is when we get the call from drain domain our resident rat man

correct way

firstly you need to make sure that any pipes that will be unused after the build are correctly capped off in the IC

I dont care if you need a sink till the last day of the build if you leave it they will come

secondly make sure all live runs are roddable

then if it has to be capped keep the cap as low as possible and make sure it is substantial

i.e 68 mm concrete slab well bedded on and covered in concrete

follow this advice for a rodent free future

cheers LLL

firstly you need to make sure that any pipes that will be unused after the build are correctly capped off in the IC.

Q. the drain/pipe will still be used after construction - would we still need to cap off as low to the open pipe as possible or could we cap off at a higher point to keep it a less expensive operation?
Thanks

[lutonlagerlout]

the proper way is to take the IC out and replace with a length of pipe
(assuming roddability and no other pipes)

lower is better

LLL