From the article: Salt caverns 1,000 feet or more underground have been used for gas storage since the middle of the last century and have a checkered history. A January 2015 analysis of Crestwood’s plan, based on documents by both independent scientists and an industry geologist, found 20 serious or extremely serious incidents in American salt cavern storage facilities between 1972 and 2012. Ten of these involved large fires and explosions; six, loss of life or serious injury; eight, the evacuation of from 30 to 2,000 residents; and 13, extremely serious or catastrophic property loss.