it will be tricky if they are indeed in the tunnel network from the ground hogs. I have seen some pretty neat videos where they pour molten aluminum down the entrance hole when just that. Large ant nest turn out really neat. Let cool and dig it out. awesome sculpture - people pay good money for them too
Speaking of which, I have one burrowing under my kid's garden shed. It's under a concrete floor so he needs to go. I have a Hav-a-heart live trap. I wonder what they like to eat to attract them in?