Neat map. “UST” (underground storage tank) doesn’t just apply to propane. It also covers gasoline, Avgas, diesel, fuel oil, heavy oil, alcohol, and other burnable stuff that I probly don’t use. Around the extended family we’ve been dealing with rule flip flops since the 1950’s. Sometimes, for instance, gasoline has had to be underground then, later, up in the air. Local fire marshals get drifty and screw with the rules occasionally.
My local fuel distributor has to use tall above ground tanks. They worry about ground water. Service stations have to bury them but they worry more about fire than ground water. But then us agricultural and light industry guys can use gravity feed above ground. Don’t even try to out guess the rule makers. If you need to store fuel just get out your checkbook and bend over.
True cost wise above ground is better. Where we live the water table allowed a UST but there are places in the state where a UST would be impossible due to the water table. Also if one lived in or near mountains a UST would not be possible due to a) inability to create a “hole” to put it in and b) the rocky terrain makes punctures very likely so one would need an AST.
IIRC the major requirements we had were minimum 10 feet away from house, 25 feet away from highway, driveway, traffic thoroughfare et al, away from any large concentrations of trees and their roots. Putting the actual UST in was the easy part hooking the generator up to the UST and house took the longest and required the most inspection before permit granted. The joke now is we hexed the weather. Bought the backup for when a hurricane or storm knocks out power, but the longest the power has been out since we put it in is 10 hours. No hurricanes, although it is a new season so who knows. LOL It’s very convenient though for when regular power goes down food and med that needs refrigeration isn’t detroyed.