Drainage on my site isn't brilliant and I'm wondering if we can dig some french drains this winter and fill them with stone sieved from the soil - it's quite a stony site. Have you come across a small machine that sieves stones out - I've seen enormous things that farmers use, but I'm thinking something more the size of a large rotavator.
as far as I kno, there isn't a small machine (apart from a hand-held sieve) that will do what you want to do.
why not do as the romans used to? dig your trenches, fill with wood(hedge trimmings, small logs, hazel is ideal) and fill over, therefore creating a land-drain, these and other forms of land-drain need somewhere to drain to, btw? have you a ditch nearby?
the best sieve that i have used is a supermarket basket suspended between tressels by strong rope and the just shaken it is very quick and can be emptied into a wheel barrow and only keeps the biggest stones, i found that with someone filling and me sieving we could fill the barrow very very quickly.
I havent a picture but will try to describe what my father made/had years ago. He had a smaller version of a kids swing frame (two triangles linked with a crossmember/pole. Hanging from that he had a boxed frame with mesh bottom. He used to half fill and bash itback and forth against a wall at the back of the swing arc. He used this a lot. When I was older he used to hold one end/I held another and we shook it. The frame held the weight of the soil, so less labour intensicve than direct riddling. I can't remember if this was for general riddling of specifically for stones.
Hi Tony, I didn't know about the Roman land-drain method, that's a possibility. Yes, there's a ditch round half the site but we need some lateral drainage because the water sits on a pan and doesn't get away very freely.
Hi Dave, Hector, thanks for the ideas. It might come down to something like that.
A Scheppach RS 400 (http://www.scheppach.com/68/?L=1&tx_ttproducts_pi1%5Bcat%5D=16&tx_ttproducts_pi1%5BbackPID%5D=57&tx_ttproducts_pi1%5Bproduct%5D=50&cHash=78865545d2) will sift out stones.
Hi Baccy Man, that's the thing, excellent, thanks very much.