Stop in for a cup of coffee

Anyone have experience getting rid of bees in the ground? Near the back corner of the property I saw them last week while out with the pup. Luckily before I mowed the grass. I have previous experience with riding over a nest and visiting the ER after getting 6 stings in various locations all at once. :eek: An event I hope to never repeat...
The area has had groundhog activity for years, so I would guess they have tapped into that network. If so, I know there are other openings including one under my brushpile. I did a good blast of spray into their hole the other night. They were active again the next day. No clue how far in the actual nest is, so assuming I need something that will gas them good. I have the things for groundhogs, but don't want a lot of smoke coming up under the pile where I can't close it off.
Boric acid works great takes a day or two and My favorite is Suspend SC, doubt you can find it localy.