Posted: 27/01/2014 at 11:03
I have had the same problem with parts of the garden as my house is a new build.
Large rocks, clay and everything else was buried in my garden and what I did was clear the lot out hundreds of bags of clay and large pieces of rubble.
Top soil, compost ( 20 x 75 litre bags ) soil conditioner were all added and now my soil is perfect.
This was not a job just for the weekend it took me weeks to do it and the area I did was 32 feet long by 6 feet wide.
You may need to check the soil what the lawn is on as well.