The Brew Cabin

I need to construct 4 soakaways to handle roof drainage of approx approx 180m2, plus a bit for surrounding patios. Using the calculations on your site, I guess that I need say 3 to 4 cubic metres of soakaway, say 0.85m3 each.
I chased up the polypipe civils plastic solution but was a bit taken aback that the price is not far short of £400+VAT each (which seems an incredible price for a bit of plastic with holes in!), so I started investigating the concrete sections method.
I tried several builders merchants and landscape materials suppliers but I have not been able to find any supplier that has ever heard of special concrete soakaway sections.
I got some prices from Jewson for inspection chamber sections and decided that the best solution would be to use 600 x 450 x 225 sections separated by engineering bricks 2 abreast, 5 sections deep, so I needed 40 sections overall. The next problem is that the builders merchants Jewson & Travis Perkins dont tend to stock more than a handful of these and are unable to obtain them unless they order 24 tonnes from the manufacturers! Some of the smaller suppliers would be able to get them but the price shoots up to about £13.50 each plus VAT. I can get some 150 deep sections from
Travis Perkins for about £7 each but I think that these may be to small and unstable.
What do you recommend, 225 deep sections at £13 each or 150 deep sections at £7 each, or is there a better solution?
I have a guy coming with a mini digger next week and I need to make a decision fast!

Martin Lloyd

Concrete soakaway sectiopns are manufactured by Marshalls and by Milton Concrete - see links section for contact details. However, they are trade suppliers and may not be able to meet a short order.

As for the simple plain concrete sections, try a Civils Merchant, rather than a Builders' Mecrchant. Jewson and TP tend to stock only the most commonly used items in the building trade. For owt a bit out of the ordinary, a smaller local co is often a better source. If you have a branch of Burdens locally, or, if you live in the NW and can contact Cooper Clarke in Bolton, they have HUGE stocks of concrete sections.
I'd always go for the larger sections. 300mm is even better than 225mm and really shouldn't be all that hard to source. I know that I could get as few or as many as I needed at less than 48 hrs notice. Whereabouts are you?

Tony, thanks for the advice about 300mm sections being preferable - I shall avoid the 150mm sections. One concern I have about larger sections is will I be able physically handle them? Do you have any idea on the weight of a 600 x 450 x 300 section?
From a functional viewpoint a 600 x 900 x 300 woul be ideal but I doubt I could handle one of these. I live between Worcester & Kidderminster. Great site!

Martin

heavy, the data sheet from Milton Concrete quotes a 600x450x300mm section @ 85Kg, but they are cumbersome and quite rough-cast, so need careful handling.

That part of the SW Midlands is not an area I know too well, so I can't suggest any local Civils Merchants. However, it might be worth giving Cooper Clarke a call, as they do deliver down there or they may well be able to put you on to a local Merchant with whom they have a reciprocal arrangement.

Cooper Clarke Drainage Division 01204 862222
Milton Concrete - 01795 425191

I tried the Oldbury branch of Burdens and they advised me that they only did 450x600x150's and that I would have to double them up. I tried Cooper Clarke in Bolton as suggested and they gave me the number of their Coventry depot. Coventry told me that they did not normally stock 450x600x300, but they were able to bring them in specially from the South of England although this incurred extra freight costs which were loaded into the price offered. For the moment I have decided to fall back on the 450x600x150's sections offered by Travis Perkins. At least they should be light enough to handle comfortably!
My latest plan is to use 18 sections per Soakaway, doubled up to create 9 450x600x300's which will be arranged in 3 columns of 3 separated by engineering bricks. Total approx dimensions of 600 wide x 1500 long x 1000 deep (plus membrane & gravel surround), then capped off with some 900x600x50 Slabs plus a layer of 100mm reinforced concrete above and 150mm plus of topsoil above that.
Do you think that the structure would collapse if a car was ever driven across it?
Also, do you think that 110 plastic drainage pipe between my gutter downpipe and the soakaway which may be only 300mm under a paved surface would be able to withstand light vehicle traffic if encased in concrete?

I find it odd that 300mm sections aren't available ex-stock. Did you ask about other sizes? You don't have to use 600x450, you could use, say, 750x600.

Your slab cover probably needs to be stronger. I'd go for 150mm thick, with A193 mesh top and bottom, and then use a C30 concrete vibrated into place. Alternatively, you might be able to get a 'biscuit' ex-stock from CC or Burdens.

The 110mm plastic pipe will definitely need encasing. Even a vc pipe at that shallow depth should be encased if it is to be trafficked.