I figured that, I have been in the streets with jackhammers and backhoes, but for different reasons.
The gas companies have their areas of responsibility but for this police station it would all be on the plumbing contractor, not the gas company, as you know they meet at the meter.
By the way, I understand that gas under pressure will follow a closed path, but open it to the atmosphere and it goes up.
Yes it does. Natural gas weighs half of what air does, so it dissipates.