SUDS: rain gardens: splash strips, swales, attenuation ponds.

[ToughButterCup]

Days are getting longer, sap's starting to rise, snowdrops blinking, cockscombs starting to fill out, worst of all the GCNs are about to move: I need to crack on. That means one thing : get our SUDS stuff sorted out.

Our Building Regs SUDS submission costs out at over £1500. Stuff that.

Why the Hell do we always need a 'product' (in our case Polystorm -' or the like ') ?  In our case  ' ...or the like...  '  is going to have to be a bit of effort a bit of planning and some digging.

 

So far we have

• read round the subject :  susdrain ,  got the susdrain manual ,
• looked at a few examples of local projects , (Lancaster Uni swale) and the attenuation pond
• searched for SUDS images to give us some ideas.
• read the BH threads about it here
• @pocster found his hard work - (at least someone keeps it real )

 

Online, everywhere everyone is all for it. Best thing since sliced bread. And that makes me suspicious.

 

Has anyone made their own raingarden, swale or attenuation pond? Is it really as simple as: get a plan, get a digger, just bloody do it?

 

Has anyone got some images of their low-tech SUDS stuff they could share please? If so, would you put them on this thread somewhere? Ta!

 

 

[Pocster]

SUDS was hard work and bollocks in the end .

Ultimately from memory the clever council required a void in the ground 10metres away from everything. This was of course impossible- it would have to of been centre of the site . It’s a ‘general’ thing they stuck on most planning irrespective of the site . So we argued . In the end they accept it was impossible- but would not remove the condition . So on paper I ‘failed’ to implement it .

Yet I have seen other applications where Suds isn’t mentioned!! . Of course ! I annoyed the council so they like to be seen to punish .

If they push on Suds then you need to throw it back at them and ask what they want . Of course they don’t know ! 

[jamieled]

Can't show you any pics as I haven't done ours. But from the start I'd planned to DIY, partly as I work with suds type stuff for a living. Plus we always wanted something quite natural looking whereas many commercial products are functional but dull.

 

It sounds like you already have a design, so if you know the intended outcome you can work out a functional design to limit the runoff rate and then figure out to make it aesthetically pleasing. FWIW I will be directing all our runoff to a ditch alongside our access track which I will form into a swale and use a pipe to limit the outflow and another to provide an overflow.

 

 

 

 

 

[Pocster]

Prove what you can do to implement it - if you can . If you can’t then prove you can’t . Suds is fine for a housing development but on a single build usually not possible 

[ToughButterCup]

Just now, jamieled said:

...

It sounds like you already have a design, so if you know the intended outcome you can work out a functional design to limit the runoff rate and then figure out to make it aesthetically pleasing.

...

 

I have a series of images of designs in my head and on paper, but as @pocster points out above; 'tain' easy.  And I'm getting to the stage now where I want the job done - 4 / 5 years at this lark is enough. And to get the job done efficiently and well, I now realise that - if I'm going to do the work - I have to over-plan so that the absolute basics are right, even if I fiddle and change the detail . I mean Hell, a woman is going to get involved in the process too, so it's bound to change innit? ?

 

I agree @pocster, SUDS is too grand a term for house-level stuff: but everyone (in this sector) knows what SUDS means

[jamieled]

8 minutes ago, pocster said:

Suds is fine for a housing development but on a single build usually not possible 

I think one of the problems is that most of the examples are large scale for housing developments. The principle of suds was always to limit the runoff rate and there's no reason that can't be done on a smaller scale as proportionately you need less storage volume. However, it does need some space, but for a domestic build there are probably a few clever ways of including it as part of a garden (small wetland?).

[Temp]

What have they actually asked you to provide?

 

I proposed a rainwater storage tank with overflow to a ditch and they accepted it, despite it not providing any storm attenuation once its full. Comes in very handy for washing cars and watering lawns in summer. We went this route because a previous house had one constructed at the same time as the foundations and immediately adjacent. Think small cellar full of water (but this was Belgium). 

 

Think our current rainwater tank is only about 2000L but wish it was a bit bigger. Something like this.. https://www.tanks-direct.co.uk/2000-litre-underground-water-tank/p6501  mounded on a concrete base underground. Building control allowed it close to the house but best apply the 45 degree rule. eg not deeper than a 45 degree line from the bottom of your foundations.

 

If it hadn't been accepted I was going to propose at a combined rainwater storage and and storm surge attenuation tank like this https://www.rainwaterharvesting.co.uk/suds-with-rwh/rain-activ-dual-garden-system-123

 

 

 

Edited January 26, 2021 by Temp

[ToughButterCup]

2 minutes ago, jamieled said:

...  but for a domestic build there are probably a few clever ways of including it as part of a garden (small wetland?).

 

We are -every year- inundated with GCNs. And I (we) love them. So we have to have a boggy area and maybe an attenuation pond. We already have four or five hibernaculars.

I can drive a digger, I can read plans, but I also know that a little knowledge is a dangerous thing. And just a little experience of landscaping with a digger is potentially dangerous. No going to stop me mind!

 

2 minutes ago, Temp said:

What have they actually asked you to provide? ...

 

Our BR submission talks about Aquacells (sized according to the PERK test) . Well we're on clay, so that went well didn't it? We need to shove enough of those babies in a friggin' 'ole big enough  to moor the Hindenberg in it. £1500 worth. As I say above. Stuff it.  I would love to have a big rainwater water tank under our drive.... but.

[Temp]

So it all has to be disposed of onsite? There is no where else to discharge to even after attenuation? 

 

Edited January 26, 2021 by Temp

[Temp]

12 minutes ago, ToughButterCup said:

We already have four or five hibernaculars.

 

Could you replace these with a drainage mound?

[ToughButterCup]

1 minute ago, Temp said:

So it all has to be disposed of onsite? There is no where else to discharge to? 

 

Nearly.

The outline flow plan is

 

From roof / hard standing > raingarden > swale > bog garden > attenuation pond > overflow >undergound piping  to IC on the  digester discharge pipe > stream

[ToughButterCup]

1 minute ago, Temp said:

Could you replace these with a drainage mound?

 

Now there's a thought.

Most of them are uphill from the main water sources (rainwater downpipes), but one or two hibernaculars would not be damaged by very slow overflow from the pond.

That's a brilliant idea @Temp, thanks!

[Temp]

What people propose to Building Control and what they actually build are sometimes different.  I can imagine some people might propose a drainage mound with all the necessary calculations and actually build a mound that can be inspected. But you know mistakes happen and the pipes leading to drainage mounds do occasionally get connected to pipes leading to streams. 

 

   

 

 

 

 

 

 

[Ferdinand]

2 hours ago, ToughButterCup said:

Days are getting longer, sap's starting to rise, snowdrops blinking, cockscombs starting to fill out, worst of all the GCNs are about to move: I need to crack on. That means one thing : get our SUDS stuff sorted out.

Our Building Regs SUDS submission costs out at over £1500. Stuff that.

Why the Hell do we always need a 'product' (in our case Polystorm -' or the like ') ?  In our case  ' ...or the like...  '  is going to have to be a bit of effort a bit of planning and some digging.

 

So far we have

• read round the subject :  susdrain ,  got the susdrain manual ,
• looked at a few examples of local projects , (Lancaster Uni swale) and the attenuation pond
• searched for SUDS images to give us some ideas.
• read the BH threads about it here
• @pocster found his hard work - (at least someone keeps it real )

 

Online, everywhere everyone is all for it. Best thing since sliced bread. And that makes me suspicious.

 

Has anyone made their own raingarden, swale or attenuation pond? Is it really as simple as: get a plan, get a digger, just bloody do it?

 

Has anyone got some images of their low-tech SUDS stuff they could share please? If so, would you put them on this thread somewhere? Ta!

 

 

 

The thing about pro-attenuation ponds is that they have controlled outlets to flatten the water drainage 'lump', so to speak. Usually means electronic control.

 

Otherwise they would be a big soakaway with an overflow.

 

Do you have somewhere to overflow to?

 

(I think your flow sequence is overcomplicating it, unless you want all those garden features) 

 

I  think in your case I would suggest something like one of those waterholes where lungfish live when they dry out. Make it big enough (ie perhaps embankment made from the diggings) to be a pond deep enough to absorb a sufficient mass of water to cover peak events to your chosen frequency or time period, which will go down to be a bog garden during dry spells. But have a deeper bit at the bottom with a liner to provide a swimming pool for the newts that lasts longer as a pool. Then have an overflow over the top for *real* super events, and have a pipe through the bottom of the bank with a plug (or a portapump) so that you can part or fully empty it through the overflow if another flood event is coming when it is full..   

 

That will let you smooth out flood surges, hopefully normally by themselves.

 

You need to size it. For my housing estate site it was about 425 sqm and 600mm deep per Ha of site area if that helps ?. Try working with numbers for a peak rainfall of 2 hours over your house / hardstanding or garden area (both lots have to go somewhere), analagous to Regs for soakaway volume related to your roof area. Then guestimate from there on the generous side.

 

All you need is a .. er .. digger.

 

In spring and autumn you will be able to film a Lancashire version of the Hippopotamus Song.

 

[Temp]

26 minutes ago, Ferdinand said:

Do you have somewhere to overflow to?

 

@ToughButterCup mentions a stream earlier.

 

[jamieled]

1 hour ago, Ferdinand said:

Then have an overflow over the top for *real* super events, and have a pipe through the bottom of the bank with a plug (or a portapump) so that you can part or fully empty it through the overflow if another flood event is coming when it is full..  

The plug might not be necessary. Size the outflow pipe to allow no more than the greenfield runoff rate for the design storm (when the pond is at top water level) as you're normally allowed to discharge that. That way you're not reliant on undoing a plug or a pump starting and it will ensure it works with a sequence of events. It also stops you from needing so much storage as the near constant greenfield discharge can be removed from the storage volume. A step up from this would be a hydrobrake for the flow control and while they can be manufactured pretty small they're probably un-necessary for a domestic suds for a small house.

[Ferdinand]

1 minute ago, jamieled said:

The plug might not be necessary. Size the outflow pipe to allow no more than the greenfield runoff rate for the design storm (when the pond is at top water level) as you're normally allowed to discharge that. That way you're not reliant on undoing a plug or a pump starting and it will ensure it works with a sequence of events. It also stops you from needing so much storage as the near constant greenfield discharge can be removed from the storage volume. A step up from this would be a hydrobrake for the flow control and while they can be manufactured pretty small they're probably un-necessary for a domestic suds for a small house.

 

Yep - that's good.

[Russell griffiths]

this is my one. 

[Ferdinand]

Just now, Russell griffiths said:

this is my one. 

 

Can you lend him the digger for 15 minutes? 

[rh2205]

In some areas they are pretty strict now, I’d plan for some kind of vortex they can be manufactured pretty small like mentioned unless you are somewhere super hilly with high runoff rates plan for a device working to 2-5l/s as anything lower will just cause a maintenance headache and no sensible person would want that done anyway. For small developments stay away from orifices or other small pipe arrangements unless you can design a completely sealed system or like picking out leaves and flooding your driveway. Also most authorities hate any kind of pumped system and then your really making a rod for your back as you might want a back up pump to avoid flooding yourself out of the first pump fails in a storm. Make sure you are not just relying on some crappy building regs guidance on sizing a soakaway written in the 1990s as it’s moved on a bit since. There’s some free websites online for calculating both greenfield runoff rate and storage requirements:

https://www.uksuds.com/drainage-calculation-tools/surface-water-storage

[Jenki]

@ToughButterCup, how did you resolve this, did you end up DIY'ing a solution? Any source of info for design. I have a slope on my site and an existing rubble drain, so would love to create a pond/ wetland area, possibly a swale instead of just burying crates.

 

 

[saveasteading]

I have done swales with a simple pipe as an overflow. As it is at the top it always has the limited head so it is predictable and calculable.

It worked fine.

Of course where the water goes next can be important.

The point about leaves and blockage is a good one. You could use chicken wire and regular maintenance, or get as complex (weirs and baffles) as necessary.

A swale works better than crates as there is evaporation as well as (not in your granite) the soakaway function.

[Jenki]

3 hours ago, saveasteading said:

A swale works better than crates as there is evaporation as well as (not in your granite) the soakaway function

This is what I'm working with.

We want a wetland / pond area to the front of the house. This is the track leading to the house, house foundation top left.

The red line is an old rubble drain, and my treatment plant uses this. It works well, and now I've put a pond further to the left of the red line ( other side of rubble drain for the plant) it slows down the run off from the field. I think I need to improve the holding capacity a bit maybe some crates at the right side of the red line.

I'm thinking the rainwater from the house is directed into a wetland area and run this into a pond (green line), then an overflow from the pond into a swale created near the blue line, this eventually running into the existing rubble drain, if it hasn't already gone, all the land to the right drops towards the coast, 500M.

So looking for design details so I can spec this up and satisfy my BCO, who is ok to work with.

I'm more leaning to pond then overflow to soakaway for BCO, but implement the above.

[jamieled]

@Jenkithe suds manual might be a useful place to start for some detail. I use this for schemes approved by building control.

 

Item Detail (ciria.org)

 

 

[saveasteading]

13 hours ago, Jenki said:

pond then overflow to soakaway

 

1 hour ago, jamieled said:

suds manual

It is worth writing your strategy with references to the suds hierarchy.

Makes it easy for the bco, or planners, to accept without passing on to another party.

 

Bottom line....no more water running off site than always has, perhaps less. 

And spreading it out and delaying it as you propose may even reduce problems downhill. A French drain parallel to the slope is a cheap and easy soakaway, and often the best.