Damp proof and Screed by Exterior Door

We have a Soil pipe next to the front door (thanks for the help in stopping it leaking!) which exits the house under the threshold of the door (a course of bricks below).
I'm trying to work out how to reinstate the screed and DPC having now cleared away all the cracked/bulging screed that previously sat upon all manner of junk (sand, plaster, rumble etc.) in the door way.
The problems are : - the soil pipe runs diagonally below the doorway's threshold (1 course of brick below). - the inner course of bricks don't really exist, the "cavity" was filled with rubbish, and the clay soil pipe has concrete encasing most of it. - think a liquid dpc had been used previously, can only find bits of the plastic DPC at the furthest corner of doorway away from the pipe. Signs of liquid DPC in remove concrete and next to stack.
On the positive side, the damp has now gone (after fixing the stack), and we have a porch so I guess the exterior door is less "exterior" now! - and will hopefully attract less damp problems.
So suggestions please on how to make good, before tiling with Procelain... Thinking of throwing a load of sand back in the hole, some mortar, some liquid DPC, then screed, but this would bridge the cavity as previous.
Thanks,
Tim.
PS could post a photo/diag if that would help? The threshold sits on the exterior course of bricks
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Happy to help but a diagram with plan and section would be useful chris
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Hi Chris, thanks for the offer of help. Hope the annotated photo will help explain my problem, if not shout and I'll try again.
http://uk.geocities.com/ snipped-for-privacy@btinternet.com/SoilPipe.jpg
Cheers, Tim.
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