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Skeletank Drainage Attenuation


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#1 quintain

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Posted 04 April 2016 - 10:24 PM

Okay my latest need to know matter is cost of a serviced plot SuDS attenuation system where I am recommended (so far) to use Skeletank.

I have seen online the Skeletank use and procedures but at a stated cost of £250 per 300l capacity crate where probably 5 crates per house is needed it is expensive.

Skeletank does seem to be user friendly with no major skill set needed for its installation and a minimum ground cover of 150mm.

I welcome any advice or knowledge on Skeletank or alternatives for this controlled discharge rate drainage need.

#2 jsharris

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Posted 05 April 2016 - 07:21 AM

We used 20 off heavy duty Wavin Aquacell crates, bought on ebay for around £5 each IIRC. Each holds 196 litres (I think), so 20 gave us the needed capacity for both our roof run off and the run off (more like drain-through) from the permeable pavers we used for the drive.

Worth hunting around, as they often seem to be left over ones from bigger projects (ours came from a big civils job going on just down the road).

Search for "soakaway crates" on places like ebay and gumtree and see if you can find any nearby bargains.

Edited by jsharris, 05 April 2016 - 07:26 AM.


#3 quintain

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Posted 05 April 2016 - 08:39 AM

Wow
Thank you
What a price...well done.
I will keep a look on ebay etc.

I will research but did you find them easy to install.

#4 jsharris

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Posted 05 April 2016 - 09:01 AM

Yes, well worth scouting around, as you can get lucky and do as I did, find a nearby site where the stack of left-over crates was just a nuisance to them. They even delivered them for me, as they were only a couple of miles up the road.

There are several makes of soakaway crate now and the only thing to watch is the load rating, if you're doing as I did and putting them underneath a drive. If they are going under a lawn or garden then the light duty ones are fine.

They are easy to install. Just dig a hole big enough to take the size of crate array you need, lay terram membrane in the hole, stack the crates in and fit the locking clips/tubes in place to hold them together, and knock out where any drainage pipes are going to fit. Then pull the membrane up the sides and fold it over the top, like wrapping a parcel. Cut two slits in the membrane over the place where drainage pipes are going to fit (if you're connecting them to rainwater drainage) and push the pipes in. Backfill around the crates with shingle or free draining stone and you're done.

We fitted 16 crates under the main part of the drive and another 4 under the drive just in front of the garage, so we have in total around 3,920 litres of surge rain water storage capacity.

#5 temp

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Posted 05 April 2016 - 11:01 AM

Quintain - Do you need a very big soakaway or just a buffer tank to control the rate of discharge into a drain/ditch?



#6 quintain

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Posted 17 April 2016 - 09:57 AM

Thank you both and my regrets over the delay in replying.

I am now more aware of the need for the specialist skeletank system; my levels are rather critical and the SuDS system has to work within close parameters i.e. I cannot dig a deep hole for either a soak away or conventional crates on parts of my site.

I am still investigating SuDS requirement/s and any alternative to Skeletank crates.

Again thank you for your input.

#7 jsharris

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Posted 17 April 2016 - 10:16 AM

It sounds very like our situation. We built on impermeable, very hard, clay, but on a slope. We found that there was a narrow band of relatively free draining soil along one lower edge of the hole we excavated for the crates, so fitted them at a depth which meant that one corner of the big array of crates had it's lower edge "just" in the permeable area. The volume of the surge storage is more than enough to take a very heavy downpour, which may well then take many hours to drain away through the small area of permeable ground.

We did have to lay things out very carefully under the drive, making sure that the crates were at just the right level so that they didn't end up sitting in the clay. We made the hole a fair bit larger than the crates all around, and backfilled with hardcore, in the hope that we could improve the soakaway performance a bit, by allowing drainage around all sides of the crates to the corner where the permeable soil is.

I tested ours when clearing out our borehole, by pumping around 1500 litres per hour of water into it for whole days at a time. One day I pumped around 20,000 litres of water into the soakaway and the only indication was that the pavers at the very bottom of the drive started to get a bit damp, as we'd clearly waterlogged the whole of the drive permeable sub-base and filled the crates, but I was surprised that we managed to drain water away at a rate that must have been a fair proportion of the pump capacity - I'm guessing that we were draining around 1000 to 1200 litres per hour from the crates, pretty impressive for such a modest area of permeable drainage available.

Edited by jsharris, 17 April 2016 - 10:17 AM.