Discharge ground water to dyke or do I have to put more money in the ground with soakaway crates?

[Bramco]

Hi,

 

We have a dyke at the front of our property which used to run all the time when the gypsum mine at the end of the village was still working.  Now it's dry, except for exceptional rainfall.

 

The ground is clay with poor but permeability rates are nearly acceptable at the front of the property. Our SE has designed the drainage system as 2 massive soakaways. 26m3 each.  So you can imagine the price we're being quoted by our contractors.

 

Also, it seems ridiculous that we're contemplating burying a massive amount of plastic in the ground. It's environmentally crazy!

 

The dyke btw now only runs when we get a biblical rainstorm overhead for a few hours. If you took the rainfall catchment area that contributes to this, then our development would be tiny.  We're talking several sq kms against a normal house and patios.

 

I contacted the flood team at the County Council and asked if  'we can simply run a pipe from a manhole at the front of the property straight into the dyke?'

 

Their response was 'Providing there is no increase in flood risk as if problems were to arise from any additional flows, from a civil point of view you would be responsible as you made changes to the flow of water. Or the asset is not a highways asset. Yes you can connect.'     It's not a highways asset btw.

 

I should add that further downstream on the dyke, are a bungalow and 3 houses that all discharge into the dyke. The dyke eventually discharges into a brook which normally has water in it but that's a mile or so away.

 

I think I need to convince BC that discharge to the dyke is OK but who do I have to persuade (BC or EA) to take a pragmatic view on this and what evidence do I need?  Are there consultants who can help?

 

Simon

[JohnMo]

Do you have to use crates?

 

We certainly didn't, and have been approved, we are Scotland, so rules may be different.  We had 43m3 soak away for treatment tank.

 

30-50mm below perferated pipe, 10 to 20mm above, trench wrapped in geo Tex fabric.

 

 

[Roundtuit]

I don't see why you shouldn't; if its at your boundary, unless you know otherwise, you probably own at least half of it. We got permission to discharge into our dyke from our local internal drainage board.  They'll probably want a proper concrete headwall, but that's not a biggie.

[Bramco]

11 hours ago, JohnMo said:

Do you have to use crates?

 

I'm told the alternative would be to make the soakaway 3 times larger and use gravel - due to the voids in the crates being nearly 100% and gravel about 30%.

 

12 hours ago, JohnMo said:

30-50mm below perferated pipe, 10 to 20mm above, trench wrapped in geo Tex fabric.

 

I'm assuming you mean gravel above and below?

[Bramco]

11 hours ago, Roundtuit said:

I don't see why you shouldn't; if its at your boundary, unless you know otherwise, you probably own at least half of it. We got permission to discharge into our dyke from our local internal drainage board.  They'll probably want a proper concrete headwall, but that's not a biggie.

 

The lane the other side of the dyke has no owner - it's an access lane for people owning land along the lane. 7 houses and a farm and on the opposite side fields.

 

I'm taking the email from the flood authority that I mentioned above as permission.  The internal drainage board don't manage the dyke, it's too small.

 

And while we might have a 'yes' from the flood team, there's the Env Agency rules and building regs.   Do we have to comply with them all, or is there one that trumps the others?

 

Simon

Edited November 26, 2021 by Bramco

[Roundtuit]

1 minute ago, Bramco said:

 

The lane the other side of the dyke has no owner - it's an access lane for people owning land along the lane. 7 houses and a farm and on the opposite side fields.

 

I'm taking the email from the flood authority that I mentioned above as permission, the internal drainage board don't manage the dyke, it's too small.

 

And while we might have a 'yes' from the flood team, there's the Env Agency rules and building regs.   Do we have to comply with them all, or is there one that trumps the others?

 

Simon

The IDB didn't manage our dyke either, but we still needed their permission. I'd ask them if you haven't already - if they're not interested, they might be able to point you in the right direction.  BC had no interest once the IDB had ok'd it.  Don't know about the EA, but pretty sure they were not involved in our case.

[Bramco]

18 minutes ago, Roundtuit said:

The IDB didn't manage our dyke either, but we still needed their permission. I'd ask them if you haven't already - if they're not interested, they might be able to point you in the right direction. 

 

I've been in touch before about the culvert - so will check with them today.  Thanks for the tip.

 

Simon

[joe90]

Well I was lucky that our  BCO officer was “sensible “, he mentioned a soakaway and I said “you mean a swimming pool?”, I then explained that in our solid yellow clay any pit will fill with water then just overflow!!, I told him the ditch at the bottom of the garden was already taking all the rain water that fell on the site and the house was not going to generate anymore rain fall and I wanted to pipe the water straight to the ditch, he agreed ?

[ToughButterCup]

A dyke is a dyke. Discharge to it. Our BCO couldn't have cared less about where we discharged. 

 

Your BCO might care,  but you'd be unlucky . 

[SuperJohnG]

We are in Scotland and just had to show SEPA that the ground wasnt free draining. I discharge both rainwater and the treatment tank output into the burn (small river) that runs through the plot. 

[Gone West]

There wasn't room on our site for drainage crates so I asked the BCO if I could discharge surface water onto the lane, which runs down to a ditch, and he was ok with it. I asked the Highways Dept. and they were happy so I asked them to email the BCO and it was sorted.

[Russell griffiths]

Can you get a hydrologist to do roof area calculations, then discharge amount, submit this to council and it ticks their box and they go away. 

I did one cost £1200 but I can discharge all rainwater and sewage treatment plant direct to pond, job done. 

[Bramco]

Thanks for all the comments and suggestions.

 

I contacted the IDB with some info from the SE that had done the original drainage plan with gazillions of m3 of crates. He'd come back to us with a revised plan with a water brake and a pipe through a headwall into the dyke.  He'd estimated the flow from the newly impermeable area on the site would be about 5l/s/h.  The IDB said that the maximum flow they are OK with is 1.4l/s/h which is the greenfield flow rate.

 

I'd worked out that on our 0.4 hectare plot, the increase due to the newly impermeable area would push the overall flow about 6% over this.

 

When I asked if this was OK, they came back saying they were OK with it and as we were about 1.5km from a managed watercourse, they couldn't imagine how they might charge us for the excess.

 

Weirdly, the IDB boundary runs along the eastern edge of our land, which means that the dyke in front of our land is not within their area but the house just down the dyke is.  when I questioned why they'd put in a comment on our planning application, they said they tried to comment on most applications, even if they were out of their area - which strikes me as an utterly ridiculous waste of time.

 

Anyway, back now to the SE for re-revised plans and to the LLFA asking for formal permission to put in a head wall in.

 

Simon