re: Natural Gas Underground Storage Question

TigerCliff and thejudge pretty much gave you the perfect and complete answer. Storage of natural gas is monitored by pressure. Mercaptan (the odorant that everyone recognizes as natural gas) is usually added along the distribution lines. This was generally done at a compressor station by Columbia Gas System companies, and I imagine most other natural gas companies did the same. Natural gas actually does have a natural odor to it, but it's very light and subtle, and tends to be a teensy bit on the sweet side for an aroma. But again, it is such a light aroma that it is essentially unnoticeable to anyone who is not actively and intentionally trying to detect it.