You'd think a tractor mounted rototiller could solve this problem.
Getting rid of the treehugging lefty librats in Boulder would help, too. THEY'RE the ones who are against control of these pests -even if they carry plague.
Well, if the rototiller can dig down 12 feet, it might. The burrows go way down and the little fellers can eat through just about anything. They paved a road near the farm and for a couple of years one pup lived in the middle of the road. He just ate through the asphalt when they covered the hole.