When I fly over the midwest and rockies, I'm amazed at all the roads which seemingly go nowhere, with no dwellings along the roads, no sign of man. That is until you get to the end of the road and see huge parking lots, or at least you think they are parking lots. That is until you realize they are hatch covers and underground complexes. They are all over the place in some of the most desolate areas.
My theory on the gas storage sites is that they are secure. They are monitored remotely for release. By design, they are willing to let munitions corrode and slowly release their contents into the landscape, where there ain't much for it to go noticed by. It's a lot cheaper than handling and disposing the stuff. That legislation only applies to non governmental businesses.