Flooding in clay soil - Would attenuation cells help?

[65-1178784189]

Soakaway and clay soil – yes, I know you must be fed up with questions like this, but I’m a newbie and I’ve got to ask!!!!

My garden slopes away from the house. Hurrah so far!! At the bottom of the garden is a “blind� ditch – it used to serve the ends of the gardens in the street to drain away surface water from the gardens, but over the years has gradually been blocked up beyond my property.

The soil is clay and when it rains the "ditch" fills up and overflows into the garden, flooding the bottom part.

Could I solve this problem by sinking Attenuation Cells into the centre of the ditch and covering them with soil and turf, and having French Drains running into these from either side (also covered with soil and turf)? My thinking is that the French Drains would act as extra drainage as well as diverting water into the Attenuation Cells, especially if the drains were deep and wide. I know that in clay soil the Cells will only provide a “storage tank� for the water but perhaps it will prevent the flooding that is currently happening, especially with the “back-up� of the French Drains which would act as a sort of soakaway in their own right. Or would it be just as good to use a traditional soakaway in the middle of the French Drains instead of the Cells?

If this is a feasible solution should the French Drains be surrounded with a permeable material to prevent silt build up? Also, how would I “connect� the French Drain to the Attenuation Cells as I couldn’t use a pipe – or could I, somehow?

For the French Drain (or traditional soakaway, if this is the way forward) does it matter what materials I use? I have loads of old slabs that I could break up into small pieces and also old bricks.

This is a bit of a rambling post, but I hope it makes sense!!

[lutonlagerlout]

well really alan the clown that blocked up the ditch should unblock it or build a culvert,it was put there for a reason
as for clay my head BCO told me last friday that if water is stored in clay it eventually seeps through fissures
ahem
fench drains have long been discredited due to silting,if you build a suds or soakaway it needs to be deep to stand a chance of working
hope this helps
LLL

[Dave_L]

That's what I'd do - cheapest option is to unblock the drainage ditch. Is it easily accessible? An hour or so with a small mini digger will have it sorted or a day with a shovel!

[bobhughes]

If a drain like this has been blocked up then surely the council or river authority or someone is responsible for sorting it out?

[65-1178784189]

The ditch has been blocked up over decades - there's absolutely NO way this will ever be unblocked.

Bearing this in mind can anyone offer advise about the issues I've raised, please (keeping the ditch out of the equation!!)?

[seanandruby]

imagine that ditch taking all the water from you st, its little wonder it floods. the ditch was put there for drainage, so you really should be looking along those lines. just how many cells do you expect to get in a ditch? does the water disappear fast or slow once the rain stops? if water soaks away from the lowest point, once you place your cells then that will maybe make your property the low point of the st. maybe some photos would show us more.

[65-1178784189]

We're the highest and first house on the slope - so no other water would drain into our garden - only what is draining off our garden. Does this help?

[flowjoe]

You can install as much underground drainage and storage area as you like but if the volume of storm water entering it is greater than the capacity of the clay sub-soils draining ability then you are p*$£ing in the wind.

You need a site visit and possibly some trial holes to determine the capacity of the sub-soil, if it is not up to the job then forget gravity and install a pump system.