Old cesspit where I want to put foundations (Long question!)

[stuboy]

I've discovered a 4ft diameter brick-built cesspit about 2ft below ground in the middle of the back trench of a proposed single storey extension.

It is taking a 2 foot bite out of the bottom of where I want to throw some concrete.

Building Control, my officer is away for the week, so the duty surveyor told me to get someone in to look at it and provide them with drawing about what we propose to do.

My builder/advisor said he had done umpteen extensions in this area and never found a cesspit and that we are very unlucky. He said 'You've paid building control all that money. Get them to tell you what they'll accept'

My surveyor said the same as the builder.

I don't want to pay loads for a structural engineer to come in and say 'You need a slab of concrete over that'.

I am going to knock up a drawing of a mesh and rebar concrete slab with extended depth round its perimeter and take it to Building Control to get them to say either 'Fine' or 'No, you want to do it like this' to try to get them to help.

Does anyone have any suggestions?
Can the slab form part of the trench part of the footings like a lap joint or does the top of the slab have to finish at the bottom of the trench bit ?

Do I have to fix the two together with rebars/mesh?

Cheers for any help, Stuart

[stoneyboy]

stuboy,
Assuming the cess pol is not in use knock down the sides of the cess pit and fit PCC lintol(s) over the gap. Your surveyor should be able to do the load calcs to determine the size of lintol needed.
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