Please review my drainage design

[Hilldes]

Here is my draft drainage layout, shortly to send to building control...

There are a few considerations:

• The pipe runs under the house can have limited fall - as they need to go under the beam and block floor and over the ring beam - so basically one course of concrete blocks + mortar = 225mm. At a min fall of 1:80 this limits the distance from stack to point of exit foundations to approx 7m. The ground workers have said we can run services through the ring beam (RC ground beam) but I'm keen to minimise this.
• The exiting foul drains are relatively shallow - e.g. the exciting IC closest to the road (IC4) has an invert level of just 8080mm below ground level. So need the pipe runs to be relatively direct from new house to IC4 (or connection at the road boundary).
• All the pipes between new house and outbuildings are existing - and these connect to our static caravans in the back garden (not shown) and site WC as shown in the outbuilding - so these need to remain until new build completion.
• It will get quite busy with services in the side access between new house and outbuildings - e.g. gas end electric need to be routed from the existing garage into the plant room in the new house, and water supply will need to come to the plant room from the front too. The plant room will be located at the lowest foul stack in the diagram.
• Trying to minimise the number of ICs in the driveway - which is a U shape (in 2nd pic). Prefer to site in borders or lawn where the can be obscured e.g. with plant pots.

Any views welcome.

[Dave Jones]

ccant see your scale.

 

 

[Hilldes]

Thanks @Dave Jones, agree that is a neater solution (assuming you mean) all 4 stacks in the house going to IC2. The main challenge with that is distance from the uppermost stack to exit the perimeter wall at the bottom of the diagram - the distance is such that the foul pipe would need to penetrate the ring beam. This cross section below shows that I have only the depth of one concrete block of fall, from underside of the B&B floor to the ring beam.

 

P.S. a ground worker that visited site to quote advised bringing the pipes out the front (right on the diagram) as I had them all coming out near IC2 in an earlier design that I shared with him. Not sure what his reasoning was - maybe the congested services in the vicinity of IC2 and the need to encase the foul pipes in concrete because they run parallel with and close to the house and outbuilding foundations.

[Dave Jones]

1 block 175mm will give you just shy of 14m of fall at 13mm/m.  Can allways chip out a bit of the conc footing to gain little bit more if needed.

 

You may have sleeper walls in your block and beam that makes it a bit of hassle as well, nothing that cant be lintelled over but groundworkers like easy they couldn't give a toss about scattering manholes all over your drive as its not their problem!

Edited December 11, 2020 by Dave Jones

[PeterW]

Any chance of naming the rooms they are coming from as it makes a difference to the connection sequence. 

[Hilldes]

@PeterW stacks annotated with rooms they serve:

[PeterW]

Replace IC2 and IC3 with a brand new chamber and bring all the lower ones straight into it. Top two retain as is but would be tempted to run a rodding eye out top left. 
 

front soakaway I would put under the lawn - they aren’t great under driveways. 

[Hilldes]

Updated design...

 

@PeterW any real value in adding a rodding eye at the topmost stack, this is a 14m run to IC4. The next stack down the page is a similar length run to IC4.

 

Edited December 12, 2020 by Hilldes
updated pic

[PeterW]

Only amendment I would make is this. And then move the soakaway behind the pipe so nothing crosses. 
 

[Hilldes]

27 minutes ago, PeterW said:

Only amendment I would make is this. And then move the soakaway behind the pipe so nothing crosses. 

 

Thanks @PeterW will take that into account for the final design for BCO. I was originally concerned that I needed to take the most direct route to the road due to shallow drain runs, but after taking some levels yesterday, I now have a bit more fall to play with once outside the house footprint.