There is (or was) a company in Oklahoma which traveled the country mining trap and skeet shot fall zones. They have trucks with rotary scoops which dig up about the top 4-6" of dirt and send it through screeners (either shaker screens or rotary screens) to separate out the shot. They typically are paid by taking a share of the shot recovered. It can be cleaned and re-used. I have cleaned and re-used probably at least a ton of it myself back when I was shooting skeet a lot. The reclaimed shot works very well for skeet shooting, I always did better with it than using virgin shot, as it spreads better.