surface water run off to a brook

[carou]

A new build I'm doing on my land in the countryside, I'm hoping to run surface water into my own brook as it's about 15 meters from the edge of the property and the soil is heavy clay. It's seems the most logical answer rather than an attenuation tank because when the rain pours down, in the wettest times of the year, the soil not being free draining and the amount of water coming down the brook (it's taking road run off) it can on the very odd occasion burst it bank and overflow into the field (hence why I'm raising up my new build) and usually takes a good 1/2 day to begin to drain away and to stop my field looking like a lake.  An attenuation tank would just fill up from the brook overflowing. Unfortunately the architect has popped in an attenuation tank into the drawings which unfortunately I asked them to remove because of what happens but they didn't so Building Regs now have this tank in their drawings and I'm hoping they will see that it's not necessary.  Any experiences/thoughts on this please?

Edited September 9, 2023 by carou

[Dave Jones]

ah the world of common sense and building control.

 

Pretty sure you will have to install a completely pointless 'attenuation tank' to satisfy them. Just make a 1m3 cube out of soakaway crates with a pipe running straight through it to the ditch. less than £100 and paperwork covered.

[Kelvin]

My experience is the other way around. I asked for a rainwater soakaway but the architect neglected to include it. However planning stipulated we needed to add one anyway. Our burn drains into a river which has burst its banks flooding the town a few miles below us. Therefore I didn’t want to add to the flood risk problem for the town. 

Edited September 9, 2023 by Kelvin

[Jilly]

You can go into the world of SUDs and design some water holding solutions, such as a (possibly seasonal) pond or a swale, rain gardens etc, especially if you have land. 

Edited September 9, 2023 by Jilly

[saveasteading]

1 hour ago, Dave Jones said:

the world of common sense and building control

To be fair, bc didn't ask for it, but were shown it. Now you have to get the architect to understand their mistake, and then to get the design changed. That could be tricky if they don't understand water, as is very common in my experience.

What is your preferred solution? You should slow the roof water to minimise flooding downstream. 

Barrels on every rwp is my suggestion, set to dribble out in the rainy months.

[joe90]

6 hours ago, carou said:

Unfortunately the architect has popped in an attenuation tank into the drawings which unfortunately I asked them to remove because of what happens but they didn't

It annoys me when architects over rule customers, however I was a a similar position, heavy yellow clay and a drainage ditch on the boundary, BCO visited (nice chap and practical) when he told me I needed an attenuation tank I said “you mean a swimming pool”, I explained it would just fill up and stay full till it overflowed into the ditch, currently all rainwater goes to the ditch any way so he allowed direct pipe work to said ditch.

[ToughButterCup]

7 hours ago, carou said:

..... Building Regs now have this tank in their drawings and I'm hoping they will see that it's not necessary.  Any experiences/thoughts on this please?

 

Thats what happened to us and this - without any discussion this is the result ....

 

 

The BCO could not have cared less about the SUDS stuff. I had to - or rather I made him listen to - the way all the roof water runoff is ducted to the pond via ( the yet to be built) rainwater gardens. I also took notes about the conversation and sent him a summary of what we discussed via email.

 

Bottom line: if what you propose is anything like in line with National guidance then you needn't worry.

Fill yer boots here.

 

Good luck

Ian

(PS , yes, I have fallen in.)

Edited September 9, 2023 by ToughButterCup

[IanR]

I found BC to be pragmatic. I'm also on clay, and have slightly higher ground the other side of the house to the ditch that the fields drain to, so I circled the house with a land drain and joined up the down pipes to that land drain, taking all the water off the house and what would have previously drained across and under the site, straight to the ditch.

 

Attenuation tanks are useful in urban development, but aren't going to make any difference in a rural setting.

 

The land drain was a significant bit of ground works, being roughly 150m in length, but very glad I did it. The fields above me can be water logged, with surface water running across them, but the house and 10m around it is always perfectly drained.

 

[Bramco]

We had a soakaway in our plans and it was going to be expensive - £20k or so for getting rid of the soil and for the crates etc.

 

We have a non flowing dyke on the edge of the property. We had to go to the flood authority folks at the county council and to the local drainage board to get their agreement to discharge straight into the dyke - took a while but we got there in the end.

I don't remember Building Control having any say in things - having said that, the soakaway was only shown on the civil engineering drawings, culvert, drainage etc.

 

Simon

[Kelvin]

@IanR I appreciate what you’re saying about rainwater attenuation in rural settings but something @saveasteading said in response to a comment I made about our situation struck a chord with me. That was something like you want the rainwater impact to be much the same (or better I guess) after you’ve built as it was when it was just a field. As I mentioned, our burn, which is always flowing, discharges into the river Ericht which runs through Alyth. We’ve lived here for two years and have seen how high the water level quickly gets over the winter. It’s flooded out the market square a few times. I wouldn’t be comfortable if I thought I was contributing to that. 

[saveasteading]

11 minutes ago, Kelvin said:

wouldn’t be comfortable if I thought I was contributing to that. 

Bravo.

I've yet to meet a bco or architect (or planner?) who understands suds.

Not part of their inherent understanding perhaps. And of couse they get ready "answers" from the makers of storage systems who market them hard.

Flood condition? Draw a crate.

Capacity? The suppliers will tell you and provide free calculations.

Why would the bco argue with it?

The EA understand but are beholden to Goverment. Flooding willl increase.

[carou]

On 09/09/2023 at 08:07, Jilly said:

You can go into the world of SUDs and design some water holding solutions, such as a (possibly seasonal) pond or a swale, rain gardens etc, especially if you have land. 

Nice but the water off the house would drain into the ditch ok and not cause a problems so I don't believe it needs slowing down.  it's only when the ditch overflows it's got no where to go and if I made a a water holding facility it would fill up as quick as lightening by the brook not the house unfortunately so I don't really see the point in having to create one.  

[carou]

On 09/09/2023 at 10:41, IanR said:

I found BC to be pragmatic. I'm also on clay, and have slightly higher ground the other side of the house to the ditch that the fields drain to, so I circled the house with a land drain and joined up the down pipes to that land drain, taking all the water off the house and what would have previously drained across and under the site, straight to the ditch.

 

Attenuation tanks are useful in urban development, but aren't going to make any difference in a rural setting.

 

The land drain was a significant bit of ground works, being roughly 150m in length, but very glad I did it. The fields above me can be water logged, with surface water running across them, but the house and 10m around it is always perfectly drained.

 

nice but the brook would fill this up as opposed to the house if the brook breaks it's banks.  

 

[carou]

On 09/09/2023 at 09:40, joe90 said:

It annoys me when architects over rule customers, however I was a a similar position, heavy yellow clay and a drainage ditch on the boundary, BCO visited (nice chap and practical) when he told me I needed an attenuation tank I said “you mean a swimming pool”, I explained it would just fill up and stay full till it overflowed into the ditch, currently all rainwater goes to the ditch any way so he allowed direct pipe work to said ditch.

that's exactly what would happen with me, it would remain full til it overflowed into the surrounding field until the ditch subsides and the water can run off down the ditch

[carou]

On 09/09/2023 at 09:27, saveasteading said:

To be fair, bc didn't ask for it, but were shown it. Now you have to get the architect to understand their mistake, and then to get the design changed. That could be tricky if they don't understand water, as is very common in my experience.

What is your preferred solution? You should slow the roof water to minimise flooding downstream. 

Barrels on every rwp is my suggestion, set to dribble out in the rainy months.

good idea 

[saveasteading]

On 09/09/2023 at 09:27, saveasteading said:

Barrels on every rwp is my suggestion, set to dribble out in the rainy months?

You mean that?

I've done that several times. Even once with mutiple ibc units linked to store 6m3. Not pretty but an industrial unit,  and avoided the EA suggestion of a green roof. So client v pleased, and EA too.

This works so has to be better  for downstream people than a drain straight to ditch.

The bco may not be bothered, but i think we all need to do what we can.

[Amateur bob]

On 09/09/2023 at 10:42, Bramco said:

We had a soakaway in our plans and it was going to be expensive - £20k or so for getting rid of the soil and for the crates etc.

 

We have a non flowing dyke on the edge of the property. We had to go to the flood authority folks at the county council and to the local drainage board to get their agreement to discharge straight into the dyke - took a while but we got there in the end.

I don't remember Building Control having any say in things - having said that, the soakaway was only shown on the civil engineering drawings, culvert, drainage etc.

 

Simon

20k? im interested in how you could get to such a high figure, how many crates did you need?

[Bramco]

Can't remember the number of crates but the total cost with excavation, earth disposal, crates and labour was about £20k total, i.e. not just the cost of the crates - although these seem expensive when you think what they are.

 

Simon

[AliG]

I'm not sure about where you are but in Scotland it is Scottish Water who approve surface water run off, not BC.

 

They prefer a soakaway over a watercourse. To use a watercourse instead you have to prove that a soakaway is not viable.

 

So first you have to show a soakaway won't work - soil report on clay soil.

 

If the watercourse is prone to bursting its banks then they would want attenuation to slow the water down. 

 

If you don't want to do this you probably have to prove that attenuation is not viable. You would have to show that there is nowhere to build attenuation except in the area that floods anyway. I would suggest getting come pictures in the current wet weather if it is already flooded. However they do often like a nice expensive report. Normally a SE would do this, not the architect.

 

[Amateur bob]

3 hours ago, Bramco said:

Can't remember the number of crates but the total cost with excavation, earth disposal, crates and labour was about £20k total, i.e. not just the cost of the crates - although these seem expensive when you think what they are.

 

Simon

going by my house size google tells me i need 8 grates so £250x8 is £2000, does this sound about right?

[Roger440]

This is exactly the approach that causes ever increasing amounts of flooding. Having lived in a flood prone house the willingness people have to ignore Suds, for that is what you are doing, im well aware of what goes on, and how useless most of the schemes, signed off as they are, are.

 

All your attenuation tank needs is a one way valve on the outlet so it cannot "back fill". They cost a tenner.

 

I see no excuse here for just dumpng the rainwater straight to the brook. Which is what Suds is supposed to prevent. You may be able to persuade the BCO it is OK, but that just highlights how useless the system is, becuase you will have circumvented Suds,.

[Bramco]

56 minutes ago, Amateur bob said:

going by my house size google tells me i need 8 grates so £250x8 is £2000, does this sound about right?

 

No idea - but I wouldn't rely on Google.....

 

[Bramco]

15 minutes ago, Roger440 said:

I see no excuse here for just dumpng the rainwater straight to the brook.

 

For us the rainwater went to the dyke anyway, so there was effectively no change. There are 3 houses beyond ours on the dyke which then ends up alongside the village sewage treatment works (don't worry it's quite a way to that).  That sewage works dumped sewage into the dyke on 6000 occasions last year - so you might say we're helping to water it down - that's if there's any real flow in the dyke.  Fortunately we're upstream from the treatment works  😄   ........   This eventually ends up in the Trent, so don't swim downstream.....

 

Simon