Use Zippo Tracks to fill the tunnel then detonate the tunnel.
Growing up on a farm, there were always chickens, and chicken coops. Invariable, rats would tunnel into them and steal the eggs. Trapping them never totally got rid of them, so my uncle devised a plan. He trapped one alive, doused it in kerosene, lit it on fire, and let it go into the tunnels, running for it's life and screaming in fear and agony...
The eggs poaching (pardon the pun) ceased...