I'm pretty sure you've got a gopher infestation if bumps and humps is what you got out there, (moles creates wedge length depressions) it's not going to be a very wise thing to grade the field if you don't eliminate the problem cuz gophers are six feet underground in a complex network or tunnels and they will come right back out. If gophers are indeed the problem, you may want to start an eradication program as soon as possible cuz it's going to take more then one season to eradicate'em, this way, when you do grade the field at the end of the season, it won't me much trapping as before and less of a safety hazard to worry about.