"Out of service" means that an AST system or portion thereof is not in use but is intended to be returned to use. AST facilities and AST systems that are used periodically, such as for seasonal storage, surcharge storage, or standby storage, are not "out of service" even when they do not actually contain oil.
N.H. Admin. Code § Env-Or 302.33
(See Revision Note at chapter heading for Env-Or 300) #10487, eff 2-7-14