There are a couple of ways that I use;
1] a .22 cal rifle with subsonic rounds. [These do not have a loud report to upset the neighbors]
2] fill hole with used kitty litter. The smell of cats & their urine drives them away, and they do not return....
Our cats were good hunters, but the groundhogs were smart enough to steer clear when cats were in the vicinity. It was a neverending battle just defending our garden and dikes from groundhog destruction. I probably killed 10-12 of them every year, but new ones would just keep moving in.