I have accidentally run into a yellow jacket, bumble bee, and ground wasp/hornet nest over the past number of years usually working on the yard. I am alergic, but not the life threatening level, so I go on hunts for them in late fall/early spring. I find their nests, kill them, their siblings, friends, and pets. My family laughs about my intense war but never complain because they don't get stung. Bumble bees will attack and are smart. Some teenagers taught me to use a tennis racket, (they don't see the nylon strings) to kill them. I was on my back deck, minding my own business sanding down a piece of my Mopar when they last attacked. Tennis racket worked. Later, not knowing the nest was under my front bay window when using the weed eater, the nest of bumble bees got me. They even stung the heck out of the weed eater as it laying running on the ground. I ran toward the street, stomping and scraping them off as 8 of them got me. Some neighbors watched and said, "Are bee's attacking you? Duh... The wasp spray was almost ineffective against the bumblers. I used it to suppress them. Gasoline in the hole worked on the rest but dangerous. I have used Acetone and denatured alcohol on bumble bee nests too. I had the same giant ground wasp/hornet problem in front yard and looked like what you described. I was out of spray from my last war and used WD40 and it worked! Good luck. If I was in the neighborhood, I'd be happy to help you.