Hi - I am about to start keeping chickens and I plan to have run around 2M by 1.5M - I would like to keep this area mud free so I thoght i would dig out the area and fill it with rubble and top it with gravel. The idea is to be able to wash the run weekly and let the Chicken pooh soakaway and let the worms do the rest -Is this the right approach? any suggestions would be most welcome. 