SUDS problem any advice

[Dodders]

Having had a rain garden scheme rejected by Dwr Cymru ,we did a soil infiltration pit test, and a soakaway was then suggested. But the civil engineer, who is familiar with the locale, was concerned about possible land slip as we are on a slope and there have been instances of land slip in the area. So he contacted a geo-technical expert who confirmed the engineer's concern about a possible landslip due to the ground conditions. The geo-technical chap suggested further testing of the ground. However this is not possible as the machinery required to carry out the test cannot access the site, and he suggested this be done post demolition. But, we cannot begin the demolition until the SAB condition attached to the planning approval has been discharged!! I explained all this to Dwr Cmryu and the SAB team a few weeks ago, and have since watched the tumble weed roll by....

It is over 500 days and counting since planning approval for a replacement dwelling. I am beginning to think that we may end up doing a refurb (polishing a turd!) instead of a replacement dwelling as we simply may not be able to discharge the SUDS scheme requirement condition because the engineering works required to satisfy both the engineers and Dwr Cymru would cost far  too much. I would be so grateful if anyone has any suggestions. Thank you, in advance.

[torre]

I don't know exactly how SUDS works in Wales sorry but for there's a recent rainwater harvesting thread here, might that be an option? Or an attenuation tank? Long shot but are you 100% sure as a replacement dwelling you're increasing the affected area enough to even fall within SAB approval?

[Gus Potter]

4 hours ago, Dodders said:

Having had a rain garden scheme rejected by Dwr Cymru

Bite the bullet and post as many drawings as you have and supporting info. Don't hold back. If you want the best advice from the members then don't make us guess as we get fed up guessing when actually we want ot help you solve this if we can.

 

Give us all the info so we can help you properly.

 

You'll be surprised (happly) how much help you get!

 

 

 

 

[saveasteading]

Where does rain go now? Can you reuse that proven facility?

 

If you put lots of water into the ground, it will soak downwards and sideways. This can create a flow, stream, slip. 

 

The solution may be to distribute the drainage over a large area, such as a drainage field. However there is still a strong chance of water finding an easy route and the same issue arise.

Land slips go way back into the hillside following a remarkably geometric circle,  thus can affect foundations a fair way from the slope.

 

Ponds are good. You get evaporation as well as infiltration plus it works as a brake / holding tank when not full.

 

If I was the planner /bco I'd want a detailed scheme before construction. It's in your interest too.

 

[ToughButterCup]

Give us detail... summat to get our teeth into, otherwise we're just guessing - and so not helping as efficiently as we might.

[Alan Ambrose]

How about designing a best guess scheme that the LPA will approve. You can probably add a clause saying ‘subject to local ground conditions when excavation/SI is done’. Get your approval and crack on. Then redesign (and re-submit to the LPA if necessary) once detailed ground conditions are determined.

 

In terms of the actual drainage problem - as others have said, water is going somewhere right now. It shouldn’t be impossible to figure out how that happens. Likewise, I’m guessing there are known mitigation measures for slip. Piles maybe?

[saveasteading]

1 hour ago, Alan Ambrose said:

known mitigation measures for slip. Piles maybe?

Money mostly.

The Mohr the merrier (CE joke).

 

Much better to control the water. Not just write some stuff that satisfies the planners, but that respects reality,  works and has a safety factor.

That's probably a pond or swale in effect, with added green roof / water butts/ drainage field that the planners have been taught is good.

[Jilly]

See my post on Wallingford running a course. The consultants running it might be able to help. 

[Alan Ambrose]

>>> Not just write some stuff that satisfies the planners

 

That’s not what I was suggesting. The op is caught in a catch 22. I’m suggesting breaking the circular condition:

 

1 - design something convincing (best guess) that will let the planners tick their box and allow you to move on.

2 - do your demo and get the SI people to do their job.

3 - design your mitigation for real.

4 - if necessary, file an NMA with the planners detailing your new design and saying what you learnt from the SI.

 

Common sense really. If you got the LPA, yourselves, and the SI team ‘down the pub’ for an undocumented conversation, this is the practical solution everyone would agree to.

[saveasteading]

18 minutes ago, Alan Ambrose said:

That’s not what I was suggesting.

I know.  I meant what you suggest, but I'd want to be confident it will really work properly when completed. 

Otherwise it could wash out and threaten the building and/or rush off and add to flooding.

 

I've noticed over the years that many builders are contemptuous of suds. 

Perhaps some of them just don't understand drainage. 

Also that many designers see it as a tick box and don't understand water. 

 

I've discussed in detail with planners in a seminar. They were happy to agree that Suds is technical and not their skillset. Thus the tickbox is what they want.

BCO likewise might not be expert. 

Edited Sunday at 09:26 by saveasteading

[Roger440]

2 hours ago, saveasteading said:

I know.  I meant what you suggest, but I'd want to be confident it will really work properly when completed. 

Otherwise it could wash out and threaten the building and/or rush off and add to flooding.

 

I've noticed over the years that many builders are contemptuous of suds. 

Perhaps some of them just don't understand drainage. 

Also that many designers see it as a tick box and don't understand water. 

 

I've discussed in detail with planners in a seminar. They were happy to agree that Suds is technical and not their skillset. Thus the tickbox is what they want.

BCO likewise might not be expert. 

 

Sadly its not just builders who hold in contempt. Its pretty much everybody involved, including the "designers and sellers of some of the so called solutions. Like porus tarmac and block paving.

 

Porus block paving doesnt stay porus. Its obvious to anyone with a couple of brain cells to rub together. Sure, the conditions will state it needs to be maintained. Which is basically, remove and relay every three years or so. Its utter BS. No ones going to do that. The designers know that. But, as you obverve its just about ticking boxes. Actual useful implementation is irrelevant

 

My BCO told me he doesnt check any SUDS related stuff. Not interested!

 

As someone who lived in a flood prone house for a good few years, its tends to focus you on observing what goes on. And the councils are the worst offenders.

 

The whole thing has a lot of similarities to insulation installation.

[Roger440]

Sorry, thread drift!

[saveasteading]

3 hours ago, Roger440 said:

Sorry, thread drift

Want to start it as a new thread? I've got a long answer stewing.

[Roger440]

4 hours ago, saveasteading said:

Want to start it as a new thread? I've got a long answer stewing.

 

Probably not. It will just be a rant from me.

[saveasteading]

OK. Just to close then my opinion is that Suds is vital in reducing floods , and fairly straight forward to achieve.

 

[Roger440]

20 hours ago, saveasteading said:

OK. Just to close then my opinion is that Suds is vital in reducing floods , and fairly straight forward to achieve.

 

100% agree.