Soakaway not viable? Alternatives?

[Mattg4321]

Following on from my other thread re foundation design near a large oak tree, I will also need to think about dealing with rainwater from the extension. I'm told a soakaway is not possible, because it will either be too close to the oak tree, the extension, or the boundary. This seems like it's probably true, but is there a set distance a soakaway must be away from a building/oak tree/boundary?

 

I'm not sure what the current setup is, but I'm pretty sure it's not a combined drain. Property was built in 1970. A 'stormwater pipeline' is shown on the planning drawings we have from when the house was built - unfortunately not all that clear. I've not got around to it yet, but we are plot 8 in the picture and the manhole cover shown to the front right of our property is there. I guess I could lift this and pour something in the downpipe to see if that's where it goes. If so, can we just connect on to this same system in general? Architect was going on about having to pay the water supplier a monthly amount to discharge into the foul drains. Something I'd like to avoid obviously! The one shown in our rear garden definitely isn't there however. I've dug out a whole section of ground more than a meter down in this area (don't ask) and found nothing!

 

Thoughts welcome

 

[Jilly]

A soakaway has to go 5m away from the building. You could look into some SuDS mitigation but that's a palaver in itself and I didn't find my BC knew much about it.  

[Temp]

Its not very clear but this was my interpretation of the drawing. Green being the storm pipeline and red being the foul sewer - but the slope of the land might mean I'm wrong. 

 

What are the circles that I have marked in red? Are they where you have gutter down pipes or soil stacks?

 

If you don't have any soakaways I suspect you might have a combined sewer. Perhaps see if dye appears at the manhole in red near the cul-de-sac?

 

What I would do is figure out where existing rainwater goes then propose the same to the BCO when you make your Building Control Application. Normally they want a drainage diagram so I would get one drawn up and write on it something like.. "Surface water drainage connects into existing surface water drainage system at this point". Then see what the BCO says. He might just accept it. 

 

PersonaIly I would avoid asking the BCO a specific question about it.  In my experience you don't ask a policeman "Are you going to give me a ticket for going 79",  you just say good evening and let them decide if they are going to give you words of advice or a ticket.

 

[Temp]

If you don't know if you have soakaway try asking neighbours. Someone in the cul-de-sac might know if they have them.

[Mattg4321]

Thanks for the advice, the red circles you have drawn are foul drains manholes. 
 

I think there is also a dotted line connecting to the storm water drains (in green on your drawing) from each property. Just to the left of the red line leaving my property. I’m going to try and lift the ‘green’ inspection chamber to the front right of my property in the next few days. Is it possible that my downpipes eventually connect to this (along with presumably the rainwater drains from the side of the road etc)?

Edit, on second thoughts, that could just be the driveway being shown!

Edited June 8, 2023 by Mattg4321

[Dave Jones]

why cant you connect to the existing drain where the roof drains too ?

[crooksey]

6 hours ago, Dave Jones said:

why cant you connect to the existing drain where the roof drains too ?

 

SUDS regulations.

 

BCO will sometimes allow a soakaway within 3m, all depends on the site, the reason and the amount of rain.

 

Plot 8 borders the road, depending how big the flat roof is, the new run off from this roof is going to be minimal.

 

Speak to the local authority, if you are just dealing with rainwater run off, you have a waterbutt for the new extension, they should allow a small soakaway closer to the boundary where your property joins the road, there will be no future building there, and we are talking tiny amounts of water. If you have a patio now where your new extension will be, you aren't even diverting more rain to ground, simply diverting it.

 

 

[Dave Jones]

8 minutes ago, crooksey said:

 

SUDS regulations.

 

BCO will sometimes allow a soakaway within 3m, all depends on the site, the reason and the amount of rain.

 

Plot 8 borders the road, depending how big the flat roof is, the new run off from this roof is going to be minimal.

 

Speak to the local authority, if you are just dealing with rainwater run off, you have a waterbutt for the new extension, they should allow a small soakaway closer to the boundary where your property joins the road, there will be no future building there, and we are talking tiny amounts of water. If you have a patio now where your new extension will be, you aren't even diverting more rain to ground, simply diverting it.

 

 

 

thats new build. extensions can use existing.

[crooksey]

Not without written approval and usually an increase in foul water costs or a one off payment.

[Mattg4321]

There must be a soak away somewhere I think as it definitely doesn’t go into the foul drains as I’ve just checked. 
 

Who knows where it is though!

[Dave Jones]

just tap into an existing pipe ?

[Mattg4321]

 

Sounds good to me, but will I get away with it! Will certainly be suggesting this to architect though. 

Edited June 8, 2023 by Mattg4321

[saveasteading]

The rain lands there now, so where does it go?

 

It is simply wrong to connect rainwater to a foul drain. It should not have Neen suggested and should not be considered.

What size is the new roof?

 

As you say, test the existing rainwater downpipe to manhole runs. Get drain trace powder from a bm. It shines fluore ent so is easy to see.

Whatever you do don't mix brown drain trace powder into someone's jar of instant coffee for a laugh.

[Conor]

Whatever you do, don't tell the water company. This will just open up a world of pain.

 

If you have an existing storm water connection, you can use this. If it's a combined sewer, you can use this. The existing water is clearly going somewhere so I wouldn't worry about it. Lift some lids and see what is what.

 

Remember, don't speak to the water company, and on your building control drawings have the new storm drains shown on the drawing "connection to existing storm water system".