(1) For hazardous substance UST systems installed after October 13, 2018, owners and operators shall provide containment that meets the following requirements and monitor these systems pursuant to ARM 17.56.407(1)(g) at least every 30 days:
(a) secondary containment systems must be designed, constructed, and installed to:
(i) contain regulated substances leaked from the primary containment until they are detected and removed;
(ii) prevent the release of regulated substances to the environment at any time during the operational life of the UST system; and
(iii) be checked for evidence of a release at least every 30 days.
(b) double-walled tanks must be designed, constructed, and installed to:
(i) contain a leak from any portion of the inner tank within the outer wall; and
(ii) detect the failure of the inner wall;
(c) external liners (including vaults) must be designed, constructed, and installed to:
(i) contain 100 percent of the capacity of the largest tank within its boundary;
(ii) prevent the interference of precipitation or ground water intrusion with the ability to contain or detect a release of regulated substances; and
(iii) surround the tank completely (i.e., it is capable of preventing lateral as well as vertical migration of regulated substances).
(d) underground piping must be equipped with secondary containment that satisfies the requirements of (1)(a) (e.g., trench liners, double-walled pipe). In addition, underground piping that conveys regulated substances under pressure must be equipped with an automatic line leak detector in accordance with ARM 17.56.408(1).
(2) For hazardous substance UST systems installed on or before October 13, 2018, owners and operators may use:
(a) other methods of release detection if owners and operators:
(i) demonstrate to the department that an alternate method can detect a release of the stored substance as effectively as any of the methods allowed in ARM 17.56.407(1)(b) through (i) can detect a release of petroleum;
(ii) provide information to the department on effective corrective action technologies, health risks, and chemical and physical properties of the stored substance, and the characteristics of the UST site; and
(iii) obtain approval from the department to use the alternate release detection method before the installation and operation of the new UST system; or
(b) the methods of release detection set forth in 40 CFR 265.193 (2011), Containment and Detection of Releases.
(3) The department adopts and incorporates by reference 40 CFR 265.193 (2011), which sets forth standards for containment and detection of releases. A copy may be obtained from the Superintendent of Documents, Government Printing Office, Washington, DC 20402, (202) 783-3238. Copies are also available for public inspection and copying at the Department of Environmental Quality, 1520 E. 6th Ave., P.O. Box 200901, Helena, MT 59620-0901.