I have a 4" foul drain running under an area where I am going to build a single story extension, half way along it there is a brick manhole 1m deep. The foul drain clay pipe has had the top cut off and the manhole is benched to take the waste stack flow.
I can divert the stack connection elsewhere. Will it be OK to cover the cut 4" clay drain pipe with half a pipe and fill the manhole with concrete to the level where the new floor slab will be constructed. Thanks for any information on this.