A good spot to get rid of bad gas? About 15-20 gallons of it?

I not 20 gallons worth but I can use some of it for that. Well the gutter it is.

save it for the dunes bonfire. All my old gas gets used to light bonfires when we go to the desert or the dunes.

or gas bombs

I have eight 5 gallon paint buckets full of a "special blend" of gas, coolant, oil, grease, name it. Once a month there's a pickup of such liquids at a local gas station. You are only allowed to drop off one container with a maximum of 5 gallons. You just gotta love when the mix of tree huggers and politicians get together for a "solution".