Soil pipe advice

[Night Owl]

I recently posted a thread about my shower tray installation which is unfortunately work stop at the moment as I'm now waiting for a 4th tray to be delivered, not sure if they are leaving the factory warped or the courier is causing the issues.  So in the hope of ever getting the en-suite finished I've moved on.

 

Could any drainage gurus out there give me some advice on the best way to route and connect a new internal soil pipe to an outside inspection chamber?

 

I have recently created an en-suite shower room in my loft space (dormer bungalow).  For the W.C I have installed a new soil pipe (white in the picture) which runs vertically down into the ground floor bathroom.  The bathroom is in the process of being dug out in preparation for some insulation and possibly UFH.  Whilst it's dug out I want to now get this new soil pipe routed outside to the inspection chamber which serves the bathroom.

 

 

 

Currently in the corner of the bathroom (which is a bit dark in the picture above) is an old broken clay connection for the W.C which is routed down and under the outside wall foundation (Blue line is the slate DPC).

 

 

The clay pipe runs under the foundation to the outside inspection chamber (yellow line), probably about 2-3m run.

 

 

Which would be the best way to do this -

 

1. Connect new soil pipe (white) into a rest bend on top of the internal wall foundation and run it to a bend / branch connection where the broken clay pipe currently is, following the yellow line hopefully achieving the correct fall.  Replace the clay pipework with plastic and take it under the foundation using the existing hole.

2. Connect new soil pipe and run it as above but take it through the external wall below the DPC.

 

I also want to install a new W.C in the ground floor bathroom but with the waste outlet for it being roughly where the hole is currently dug in the picture (green cross).  Is there a clever way to join the two wastes together and exit through one hole to outside or would they need separate outlets?

 

The outside ground level is currently about 1 brick below the DPC blue line (I know ideally it should be two bricks and is on my ever increasing list).

 

I'm struggling to get anyone to come out and quote for this so will probably end up having to tackle it myself but need to make sure I don't introduce any issues.  Not sure about rodding access but was hoping it could all be achieved from the inspection chamber.

 

Thanks.

[Night Owl]

I had BC out today looking at some other work that's been carried out on my property.  Took the opportunity to get him to look at the drainage proposal as above.  Basically we are looking to connect the vertical (white) soil pipe with a horizontal one to a branch connection where the current clay pipe goes under the foundation.  The bathroom W.C can then connect straight onto the branch as well.  A rest bend below the branch can then direct the waste down and out under the foundation. 

BC suggested using a sleeve under the foundation and back filling with concrete as the easiest way of doing this.  Makes things simple enough regarding getting the new plastic outside however I'm not sure how the new horizontal pipe (which will be buried in the new bathroom floor slab) can be made rodable with this set up.

 

Any thoughts?