Natural gas leaked out of a PG&E pipeline in San Bruno, CA, killing an unknown number. Clearly the Buried Natural Gas infrastructure is beginning to age. Only UAV's can reasonably fly low enough in neighborhoods to create a map of NG concentration. I heard on NPR that PG&E flies airplanes to inspect gaslines, but clearly not low or often enough.
Given that Methane sensors are light, cheap and readily available:
It's conceivable that Amateur UAV's could fly a pattern and log Methane levels against a GPS coordinate.
(Does anyone else think this could be a viable task for UAVs? and Why not propose a T3 contest in which mapping methane is the objective?)