I have used this system for years after a local trapper helped me get rid of groundhogs. The first summer I used this kind of trap we caught 13 groundhogs! Last summer it was 12. They are quick and more merciful than the old leg traps we used to have. Shooting is too risky because you never know where a bullet might ricochet off of since the hogs are often next to our outbuildings when spotted. These are not for the faint of heart but they work and using the tool to set them makes it easier since the spring is hard and the tool gives you the leverage. We use the same hole over and over as groundhogs are attracted to the smell of previous groundhogs. Reusing a hole prevents having to search for the new ones which may be in an awkward site to get to easily.
Check out this site if you are not opposed to a final solution but don’t want to shoot or cart them off to torment a neighbor down the road!
http://www.setngotrapper.com/