I’ll tell you what works BUT i take no responsibility for any damage to underground utilities, nearby foliage, far away foliage, ...or anything else. I had a similar issue I tried to address with a .22, sat on the lawn in a folding chair with the gun in hand until I saw the little bugger. When I saw it’s head pole out the hole I squeezed off a shot. I thought I had won until the damage continued, that’s when I learned that where there is one there are many. Frustrated (beyond frustrated) by the continual fight and armed with some basic chemistry knowledge I mixed up a couple gallons of AN-FO and poured it into the hole, slipped in a homemade ‘igniter’ (details omitted), took up a safe position about 50 ft away and BOOM. When the dust settled I assumed I had won...until The next morning when water was bubbling up from the blast zone. Yup, I blew up the water main. I fixed that and a week later the leach pit that was located about 6-10ft in the other direction collapsed. SO let’s file this under the how NOT to deal with the critter, especially since whatever it was came back about 6 months later.
‘What I DO suggest doing (mostly because it’s really cool) is using propane gas to finish the little bugger off. Having already blown up my own front yard I wasn’t about to do this to my own yard but I had a chance to employ this method while helping the local park and rec regain control of the golf course that had become overrun by ground squirrels. I used a propane torch that was normally used for weed burning. Shove the tip into the hole and turn the valve on to fill the hole (a new hole shouldn’t take more than 20-30 seconds of gas) then turn the valve off but leave the tip in the hole and click the Piezo igniter. The gas in the tunnels will ignite and the ground will shake, you will see just how complex the tunnels were...and you might even see a flaming critter run out another opening (thus the potential damage to surrounding foliage)