Poor Draining Soil

Hi all,

Since we moved into our house 18 months ago we noticed that the soil had very poor drainage. Upon digging it we found it to be very heavy clay.

After doing some research, and ruling out a soakaway due to the fact that the clay is too deep to dig through, I decided to install land drains, connected to our main drain. The ultimate aim is to lay turf/grass seed for a lawn.

I had the top layer of clay top soil scraped out - to about 60mm all across the garden.

I marked out drains in a herringbone formation, put in geo-textile and 2 tonnes of sandstone, along with 80mm perforated land drain pipes. I connected these to my main drain, with a silt trap inbetween to prevent silting up the house drain.

I made sure there was an appropriate fall throughout to allow gravity to take it's course.

I then bought 10 tonnes of farm grown topsoil - and laid this over the land drains.

The problem is, that this topsoil I have bought, seems to hold the water like a sponge. In some areas, when you stand on it you will sink in up to your ankle. It doesnt seem to matter if we had tread the area down or not.

Does anyone have any advice how to amend this soil. I was considering 3 tonnes of river sand on top and then raking it in to improve the drainage/reduce the amount of water held.

I'm just concerned that if I lay turf, the ground underneath will be so soft that walking on the turf will just destroy it.