Joined: July 2004
||Posted: 23 Nov. 2019,09:38
Are you certain that the property has a viable DPC? One of your photies shows an air-brick half a metre or so above Ground Level (GL) which, under normal circs, would indicate the DPC is well clear of the ground.
Assuming you do have that essential DPC, and that it is working as intended, then I would look at using a one-way drainage composite laid against the wall down to that layer of limestone bnlocks (what an odd thing to find! Maybe a regulating course for spreader courses on the house?) then backfill with a clean gravel.
As for the downpipe, I can see why you would be pushed towards using a soakaway, but with those ground conditions, it's highly unlikely a soakaway would work, or work well enough. I would use that survey to argue that a standard connection to either the SW or, as a last resort (and via a trapped connection) to the FW.
Does that help at all? It seems to be, more or less, exactly the conclusions you had reached for yourself.
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