Drainage falls

[thomp1983]

Hi all,

Week after next I'll be digging out for my new drains and water pipe.

I'll be fitting 4 access chambers, the last will connect to the existing access chamber, the existing access chamber is 2m deep to the invert height.

Access chamber 1 is going to be at 1m deep and receive waste from the kitchen sink,

Access chamber 2 is going to be at 1.2m deep and is 6m away from no1, it will be on the corner facilitating a change in direction of drainage.

Access chamber 3 is going to be at 1.4m and will receive the bathroom soil pipe and is 7m away from no2.

Access chamber 4 is going to be at 1.6m and is 6m away from no 3. This will then drop 400mm over roughly 1.2m and join onto the pipe going into the existing access chamber.

The existing access chamber receives waste from 6 houses and goes under my property, it was renewed in plastic before I built my extension.

Do the falls sound acceptable for the distances covered? I worked it out based on 40mm fall over 1.8m, the last drop from access 4 isn't ideal being so sharp but will provide me with suitable rodding access to the joint into the existing pipe whereas if I just joined in from access chamber 3 I think it would be a bit far away for successful future maintenance.

Thanks
Chris

 

[denso13]

Do the falls sound acceptable for the distances covered?

Without checking it in detail it sounds ok. You will need building control involvement, I'd check it sounds ok to them as they will have to sign it off.

 

[thomp1983]

I'll be ringing our building inspector on Monday as I need to time the inspection right as the diggers only on site 2 days for the job

 

[denso13]

Sounds ok to me.

 

[Exedon]

Sketch of what you intend to do would be useful.
Is there a reason for starting at 1 mt deep?
400mm drop over 1.2 mt way too much highly likely to leave solids behind.

 

[thomp1983]

I'll sort a drawing later, starting at 1m as the water pipe is going in the same trench and has to be at minimum 750mm, and then drainage pipe needs to be a bit lower than that