Backfilling under lintel above drain pipe

[John2000]

Hello,

I’m looking at extending a concrete slab to the the edge is a lintel that jumps a pipe. 

 

As you can see in the photos the sub base that’s already poured stops short due to shuttering.

I need to extend the subfloor up to the edge of the inner course. The pipe is already incased in concrete from previous installation (I’m not touching that for love nor money) it’s disused but it’s blocked and full of water and crosses about 10 properties. More of a soakaway these days than the old soil pipe and rainwater it used to be. 

 

Anyway, I was thinking just putting down a layer of sand for compressible,

then type 1 down and compacting (gently) then pouring a concrete/SBR mix up to the edge of the lintel. (With shuttering) insulation and screed will go over top. I’ve got to backfill around the edge of the slab anyway in parts to close the gap between the poured slab and inner leaf.  

 

I do have a bit of rebar laying around I could use as an additional support running across the void?? And bedded into the backfill.

 

Thank you.

[Mr Punter]

If it is disused, could you cap it either side of your property?

[John2000]

I did consider that and smash it in but Anglian water want £750 for an inspection first, then no doubt they’ll want something more! where with a jump and build over which I have, I dodge the ludicrous payout and just remedy it. 

[Big Jimbo]

One thing i will say, is that that is a great entry point for rats, into your cavity. what ever you do, make sure you close that up with stainless steel mesh, or something else. Peace of mind will be better than rats. Believe me.

[John2000]

Thinks Jimbo. It’s gonna be full of concrete so no access either side.just working out the best way not to bodge it up. Cheers.