How would this ever be a hazard to aircraft?
I once was assigned to a MAJOR natural gas leak, where a backhoe had struck a supply line (I don't remember the diameter, but it was big enough that you could hear the gas escaping from a mile away, and actually see it escaping when nearby...distorted the light passing through it up to about 10 feet from ground). The gas company people drove vehicles right up to the leak, and explained that there was no hazard running a vehicle right next to the gas leak, as gas leaks were only explosion-hazardous when contained (like in a house)...of course a fire would be possible if you got right up to the leak with a flame...