I get them out of my backyard the year before. They made home in the stone wall, somehow they find a crack and dig in. I put gasoline in first, they hate the smell, so they leave the hole, but they still try to go back even they couldn't stay there. I filled some quick set concrete (same thing used to set fence poles) in and hosed in water. After concrete set the crack was sealed. They moved out.
I think if you keep fighting them with gasoline, they would move out eventually. But it could take longer. I tried moth ball too, but did not work out, because they push the moth ball out.