Soakaway failure

[luciasdad]

Good evening all,
We had a sandstone patio installed over the summer. Foolishly I agreed to allow the patio to be sloped toward the house. An ACO drain was then fitted and connnected to a new crate soakaway in the garden. We have no mains drainage at the rear of the house, so the soakaway was my only option - or so I was advised. Unfortunately this decision has now proven disastrous as we are in an area of very heavy clay. The soakaway empties very slowly and when we have a week of heavy rain it backs up, fills the ACO and sits against the wall of the house. I enquired if a bore hole would be a viable solution, but was advised that the geology of the area made it unsuitable. So I am seeking advice here and hopefully a potential solution. I should add that I have dug down to confirm the soakaway is definitely not blocked, and its poor performance is down to the clay. The soakaway is 1.7 cubic metres. The area of patio is needs to cope with is 60 square metres and the roof area is 25 square metres. I am based in Kent.

 

[blup]

There are standard calculations for the size of a soakaway but ultimately a percolation test is used. Unless your drainage is blocked in some way from ACO to soakaway, the ground is either unsuitable or the soakaway size inadequate. Have you done any calcs?

 

[luciasdad]

The landscapers claimed they ran a percolation test and sized the soakaway appropriately. The installation was in late July during a period of very dry weather. Plugging the sizings into ChatGPT tells me the crate system should have been @ 3 cubic metres, but that even that would eventually fill up due to the ground. I think a soakaway is not a viable option and I'm looking for alternatives.

 

[Notch7]

I think a soakaway is not a viable option and I'm looking for alternatives.

you only really have the option of connecting it to a sewer - means paying the water company to discharge surface water into it

 

[luciasdad]

Thanks - what form would that take? Would the necessary work need to be carried out by Southern Water?

 

[Notch7]

Thanks - what form would that take? Would the necessary work need to be carried out by Southern Water?

no you can get it done, but you probably need an agreement from them -Ive only ever been involved with jobs where its under building regs and the building inspector agrees to it

your water bill for the waste would go up a bit

my experience of Southern water on build over agreements hasnt exactly been positive, maybe they've improved recently.

 

[luciasdad]

in the first instance though, should I reach out to Southern?

 

[Notch7]

in the first instance though, should I reach out to Southern?

yes I guess so

it says:

"you need a pre planning enquiry wastewater application"

see number 6: discharge into Southern Water combined sewer

Sewer Connection - Southern Water

Find out whether you'll need a new wastewater connection to a property, how to apply to connect to the foul sewer, and how to manage surface water.

www.southernwater.co.uk

 

[luciasdad]

many thanks Notch