Combined foul and surface water drainage system

[Moonshine]

I have had approval from my water authority that I can discharge surface water to a combined public sewer in the road outside the front of the plot.

 

Basically a soakaway won't work on the site as the soil infiltration rate is too slow.

 

Is there anything tricky about a combined foul and surface water drainage system?

 

Can you just connect the RWP pipes to a inspection chamber to the rear of the property which has a SWP going to it, or do both systems have to be kept separate to the front of the property and combined there? i.e. combine at source and along the run of a single pipe, or have two separate pipes/systems and combine at the end?

 

I presume that the falls and sizing for the foul water will be fine for the surface water?

[CivilEng2020]

No there is nothing tricky about a combined foul and surface water sewer.

 

I'd say keep them separate and combine just before connecting to the public combined system.

 

You are right that the falls for foul water pipes will be fine with surface water, but may not be for capacity unless maybe you go for larger than 110mm pipes.

[tonyshouse]

All Re-‘s should go into gulleys to prevent smells , I would add a catch pit and clean it regularly 

Edited January 10, 2021 by tonyshouse
Catch pit

[Mr Punter]

I have done this several times and @CivilEng2020 has it spot on.  Connect both to an inspection chamber near the boundary, the theory being that if the systems are separate in future yours can be piped accordingly.  All the connections to the drain need a water trap.

[Moonshine]

15 hours ago, CivilEng2020 said:

I'd say keep them separate and combine just before connecting to the public combined system.

 

Thanks for that, there is unlikely to be any chance of separate systems in the future, and the site is a bit tight so i have planned to connect surface to IC's via trapped gullies.

 

Below is what i am proposing in schematic though need to put it on a site plan and work out CL and IL's.

[Onoff]

Any chance of changing the thread title, it's foul! ?

[Moonshine]

11 minutes ago, Onoff said:

Any chance of changing the thread title, it's foul! ?

 

and i have just seen the fowl spelling in my post! ? 

[Mr Punter]

19 minutes ago, Onoff said:

Any chance of changing the thread title, it's foul! ?

 

I assumed he was connecting the chicken shed.