/ A total of about 7.5m from the furthest boggy bit to the drain, and a drop - in stages, not evenly (yet) - of 360mm. The ground immediately under the slabs is just clay, and absolutely _sodden_.
Just to make life even more fun, the single-skinned heating oil tank's only about 750mm or so away./q
Meh spade & get digging;-) it should soon become apparent if it is going to work or not...
Jim K
Does not have to have continuous 'fall' as french drains work by osmotic pressure ... don't need a fall. Although if you can arrange one a 1:100 fall would make it more efficient in heavy water flows.
In simple terms assuming a standard 110mm perforated pipe .... dig a trench 450 wide & 450 deep ... plus depth of cover you want over the drain ...
square off reasonably well ... lay in Terram, (Geotextile membrane) put in 250mm of clean 40mm stone (ideally not limestone)
Lay in teh perforated pipe and then cover with clean stone to 150mm above pipe. Wrap Terram over the stone, and then backfill with 'as dug'
If you are emptying into a 'hole' somewhere ... install a soakaway crate ... don't just fill a hole with stone ... not efficient and clog with time. Crate would also be wrapped with Terram.
If it is anywhere near a house ... don't
Willows have well known issues with causing clay heave.
I posted earlier details on a land drain .... can collect the water via soakaway, and plant a bog garden ... again a very nice feature.
So they have more salt inside than outside? Or did you mean something else?
Andy
He's writing in syphon.
But that was abandoned as a programming language because it was a drain on resources.
I've _finally_ been over there with tools today. A trench has been dug, lined with membrane, then a 60mm land drain pipe lain in the bottom. The final stretch to the drain is in a piece of plastic guttering.
It's made one _hell_ of a difference. Next door had cleared earth away from the bottom of their garage back wall, and this morning there was a good little line of water in it. By lunch time, the land uphill from there was visibly drier, and the line of water almost gone.
We had a slight hiccup when I laid the membrane ("Hello, Mr BM - I'm making a land drain, and need some porous membrane", takes proffered roll of TDP50). Which turned out not to be particularly porous. A quick phone call to TDP - "No, you don't want that...", and another visit to the BM for a pack of TDP115 (which actually said "Drainage filtration" on the packaging) and there was much more success.
I'm not sure if 100% of the water's going down the drain, but 95%+ certainly is. And it's running FAST.
It's all laid under gravel at the mo, and we're leaving it a few days for the surrounding earth to dry out. It's VERY clayey, and now VERY claggy. Once that's done, we'll level it all off and relay the slabs.
Thanks to all for the help and suggestions.
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