10 Guam Code Ann. § 76207
(1) the facility is non-transportation-related;
(2) aboveground storage in a single container is equal to or greater than fifty-five (55) gallons, or aggregate storing capacity is equal to or greater than five hundred (500) gallons;
(3) facilities, which, due to their location could reasonably expect spilled oil to reach surface waters and ground waters of Guam and the United States.
(b) The Administrator shall require secondary containment on all existing, new or replaced AST and connected piping.
(c) The Administrator shall require under-dispenser containment on all motor fuel dispenser systems.
(d) The Administrator shall require that each existing, new, or replaced AST and piping have a secondary containment system, and be monitored for leaks.