underground is highly regulated, but many people have 100 gallon tanks above ground. My grandfather had two, my father stores 50gal in gas and 50gal Diesel. If you have enough property buy an old farm tractor and a brush hog to "mow" your land and then fill a 50gallon drum, if you truly farm you can get a farm discount (just don't use any on public roads) or some of the small stations will still give a bulk discount. They are much less picky about above ground though it seems to me gas leaking from either would cause just the same mess, however you could have a leaky underground tank and never notice until its empty where a leaky above ground tank you will notice the smell and puddle on the floor/ground.