Garden drainage problems

[marc craven]

I have a lawn that is water logged. I have dug a soak away which is next to useless. can anyone give me any advice. The lawn is approximately 12m x 10m in size, and has a gentle slope away to a wooded area at the bottom. The soil is predominantly clay.

[Nearlyman]

just to let you know you're not alone. Have the same problem:extreme water-logging on a gently sloping site on a heavy clay soil.
To make your soakaway effective you will, of necessity, have to lay a network of pipes from the higher ground in a fan like pattern culminating at the soakaway and several inches below the surface where it enters the side of the soakaway. Hence, the soakaway needs to be very deep!
I take it it is full of clean rubble? The first soakaway I built was 6 Ft deep X 5 Ft longX 3 FT wide!I covered mine with an old carpet and then turfed it. There are better ways probably.
The natural gradient of the site will reduce or even obviate need to progressively increase the depth of the channels for the pipes - which need to be perforated and laid on a bed of pea gravel - rather after the fashion of a French Drain.A membrane has to be introduced too to prevent soil seeping into the pipes and blocking them.
This is a fairly crude solution, but should be effective. It depends on how long you plan to live in your present property and if the cost and sheer physical effort is worth it: unless of course you can get free use of a mini-digger, which will churn up the lawn somewhat; and that's assuming you can get a digger on to the site. Otherwise, its all "brute strength" and perseverence.
Check to see if it's a common problem in the neighbourhood. You might even be able to check with your local council to see if it is noted for being a particularly wet area and there might even be advice available from your local planning and/or building control officer.
Best of luck :!:

Nearlyman