Soil pipe design/runs

[Jonny]

Hi all,

In the wait for planning and before wanting to commit to professional input for building regs drawings, I’m just starting to plan services etc around the house. 

The current thing I’m trying to work out is the runs for the soil pipes. These will eventually head out to a treatment plant (to be specced). 

Out of the two designs below, which would be preferable? 

One option minimises runs under the (insulated raft) slab and has multiple inspection chambers to pick everything up, the second utilises 45 deg branches. 

One option allows rodding access from both ends; the branch option only allows rodding from one end. This will need toilet, etc., removing to access?

Any thoughts on which is best? I can’t seem to find any guidance about minimising runs under the slab but common sense says less is more.

Let me know if there are any suggestions, and I'll resketch!

Thank you all

Thank you all

[JohnMo]

Top image will not work as you need an inspection chamber at each junction. 

 

2nd image you are going to be metres below surface by the time everything meets up with the fall requirements. Don't like the angles, would aim for 90 degs

 

Where is the treatment plant going? Start from there first. Longs runs equal very deep.

[Jonny]

Noted, I’ll redraw. The site is sloping, but not that much and the fall slipped the ‘design’

 

Treatment plant will be to the north/top of these drawings. Thank you 

[saveasteading]

1 hour ago, JohnMo said:

you need an inspection chamber at each junction. 

 

Simply by immediate appearance the top one looks preferable. I think as long as it is all roddable it is acceptable, but wold have to read the reg's with that in mind.

 

We are installing ours within the slab insulation, for pracitcal reasons, but with the added benefit of retaining height.

that can create 'cover' challenges outside, but overcome-able.

 

Apart from keeping trenches shallower as a benefit please consider where the digester will empty to. 

[Jonny]

I’ve found this guidance, https://info.labcwarranty.co.uk/hubfs/Technical downloads/LABCW Y-junctions under buildings.pdf

 

So this means the top option should be achievable as long as I include access/ rodding points. 
 

The treatment plant will be as close to the building as permits. It has to be on that north side due to land ownership/ a 200mm water main elsewhere 

[Nickfromwales]

Neither seem sympathetic or practical tbh, and you need to work out where you can practically add internal rodding access. In reality, this is not very practical so I'd steer away from that solution.

 

You can have clear water branched into foul runs as long as they are swept connections to join the flow from a WC. Aim to combine some of the connections and just get 110mm pipes to WC's first, then look to see what you can pick up with 50mm pipes bossed into the 110mm runs. Combine as much as you can to a chamber offset from your main entrance, as it's a bit of an eyesore if immediately outside the front door, slap-bang in the hard landscaping.

 

Have as much pipework under the slab as you like, there's no issues there; do what works best and cover it over, and get on with life.

 

Avoid the connections to the chamber that come in against the direction of flow, as you suggest some which are too far from best practice.

 

No Y junctions under the slab unless it's a straight run and its chamber to rodding access, or unless it's taking bath / shower / basin wastes, as these are considered clear (grey) water without solids.

 

This changes for kitchen and utility, as these are considered to have solids (food waste etc) being discharged from them, so are treated like foul connections; if no internal rodding access, then these need to be arrow straight runs directly to an outdoor chamber.

[Mr Punter]

You cannot join a WC in a Y.  You will need ICs.  These are best outside the footprint.  Why the soil pipe in bedroom 03?

 

As above, you need to work out your levels and take it from there.  Design the runs as shallow as possible with a fall of 1:50.