Foundation around drain

[knightshaft]

Hi,

This is my first post.

My down pipe and waste pipes over shoot the drain when the flow is anything more than a trickle. I've been told that I need to build up a couple of courses around the drain. I have dug out the surrounding soil right down to the clay (about 2 feet) as it was mashed with crap from the waste pipes.

I'm worried that if I filled the hole with fondation it may crack the drain at some point when it settles.
Should I put my fondation at this depth or refill with new soil and put the foundation nearer the surface?
Should I also leave a small gap between the drain and the foundation to avoid cracking?
What's the best mix for this type of foundation?

Many thanks in advance
Knightshaft

 

[Thermo]

nice bit of work, but if you are doing is putting a few courses of bricks around the drain grating, then youve dug a little too deep! there is no weight to a couple of bricks, so at most it would have needed a few inches of concrete and then the bricks on top of there. backfill it, compact it with the end of a lump of 4 x 2 and then fill the last 3-4 inches with concrete. if you pop along to wickes get a bag of postcrete. its quick setting and will be more than ample to do the foundation for this.
if your pipes are overshooting the drain that much, you could also put some bends on the end to angle the water down into the drain

 

[knightshaft]

Thanks thermo