So your grill is mostlikly a modified 30 or 55 gallon oil drum.
I'd do what everbody else does down there and just throw the stuff in
the water. Nobody else will care from what I have seen.
that's kind of what i was thinking when i read the question, toss it in
the water. as far as i know nobody has yet dared to claim that burnt
wood is an environmental hazard lol.