Best stone for drainage in clay

[andyr]

Hi

I need to improve the drainage in a field, some drains already in place, gravel over the drainage pipes but the clay over the top of the gravel which I suspect is stopping the water penetrating properly. I am going to try digging the clay out to expose the gravel and then top this up with more stone so there is no clay covering it or the pipes.

I also need to run a few new pipes.

What would be the best stone to get to avoid blockages and keep the water running?

Many thanks
Andy

[Muz]

I dont think the physiological factors will be as important as the likes of cost. Clay is a very dense fine particulate material, how it performs in water retention depends a lot in its exact make up and where it is. A large stone will leave bigger air gaps, but less of them, compared to a smaller stone, and so less likely to clog, particularly if the drainage surface is likely to be disturbed often

[andyr]

Thanks Muz

Think I will go for some largish stone........I think the problem at the moment is that the stone around the pipes has been covered back over with the clay and the water is struggling to find the drain. I will bring the stone right up to the surface and get shot of the clay.

[Muz]

Yes well if the clay is very plastic, water penetration will be poor, you might find treating the ground surface more effective to allow capilliarity to increase in the upper soil layer, this will allow better drainage, where your stone drains will be found more easily, even if they are covered ? Ofcourse I'm talking blind here without knowing your actual application .. some pics would be good

[JMB]

Hi andyr

On a more general view of drainage and probably more suited to drives, public areas walkways etc. I have found a site on the web http://www.pavingexpert.com/ an absolute mine of information. The author is Tony McCormack, may be of no interest but you never know!

[andyr]

Thanks Muz....will try to take a few tomorrow.......

PM
JMB......I found that site last night, very interesting.........