Around the run we dug down approx. 4-6" and started the side fencing from below the ground surface. However, on the inside of our fence around the entire yard is the apron that is stapled to the fence and then rests on the ground as an apron (probably 2" out or so). That way, it will be difficult for our dogs to dig out, for anything to come in and if something gets in (and gets past the dogs) the run is fairly secure. We don't have some of the common predators (weasels, raccoons, skunks, etc) and most larger predators have several things to get through before they'd ever get to the chickens. Nonetheless, our chickens are secure from any possible diggers.