Brian G used his keyboard to write :
Cure, is to dig either a drainage trench to a lower level so the water runs
aways (can then be filled with coarse gravel) or dig an even deeper trench
to about two foot below DPC, backfill with coarse rubble and use this as a
soakaway.

Soakaways with a clay sub soil do not work, unless they penetrate
through the clay level. Faced with the same problem, I dug a trench
around, installing a 'leaky' pipe which led to a drain, all then back
filled with course gravel.

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Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk