wheelchair accesssible organic garden
i am part of an organic community garden that has put down tar roofing shingles to make some plots wheelchair accessible. i am assuming that this isn't very organic. woudln't petroleum leach into the soil?
please advise, as i think the people running the garden think i am making a big stink over nothing.
also, what might be an alternative? would gravel or woodchips really give enough traction?