Section 22a-449o - Requirement for double-walled underground storage tanks(a) As used in this section: (1) "Double-walled underground storage tank" means an underground storage tank that is listed by Underwriters Laboratories, Incorporated and that is constructed using two complete shells to provide both primary and secondary containment, and having a continuous three-hundred-sixty degree interstitial space between the two shells which interstitial space shall be continuously monitored using inert gas or liquid, vacuum monitoring, electronic monitoring, mechanical monitoring or any other monitoring method approved in writing by the commissioner before being installed or used;(2) "Double-walled underground storage tank system" means one or more double-walled underground storage tanks connected by double-walled piping and utilizing double-walled piping to connect the underground storage tank to any associated equipment;(3) "Hazardous substance" means a substance defined in Section 101(14) of the Comprehensive Environmental Response, Compensation and Liability Act of 1980, but does not include any substance regulated as a hazardous waste under subsection (c) of section 22a-449 or any mixture of such substances and petroleum;(4) "Petroleum" means crude oil, crude oil fractions and refined petroleum fractions, including gasoline, kerosene, heating oils and diesel fuels;(5) "Underground storage tank" means a tank or combination of tanks, including underground pipes connected thereto, used to contain an accumulation of petroleum or hazardous substances, whose volume is ten per cent or more beneath the surface of the ground, including the volume of underground pipes connected thereto; and(6) "Underground storage tank system" means an underground storage tank and any associated ancillary equipment and containment system.(b) No person or municipality shall install, on or after October 1, 2003, an underground storage tank system and no person or municipality shall operate or use, an underground storage tank system installed after October 1, 2003, unless such underground storage tank system is a double-walled underground storage tank system. This section shall not apply to a residential underground storage tank system, as defined in section 22a-449a.Conn. Gen. Stat. § 22a-449o