Our community well pit (in ground 4x8 concrete box with hatch in top) would explode quite spectacularly from time to time. Hydrogen sulfide gas would supply the fuel and the pressure switch would supply the spark. That heavy wooden hatch would go 30 feet in the air, and the explosion could be heard almost a mile away. The procedure for going to work on it was to open the hatch by sneaking up to it from the side, and then retreat. If all was quiet for a few minutes, we would set up a fan to get the air exchanging in the pit. If I was lucky, there was some short skinny guy around to actually go down in the pit to work on it, but usually not.