17.56.204 SECONDARY CONTAINMENT, UNDER-DISPENSER CONTAINMENT, AND INTERSTITIAL MONITORING
(1) Any UST that is replaced or installed after November 26, 2009 must employ:
(a) secondary containment and approved continuous interstitial monitoring, as described in ARM 17.56.407(1)(g) and (2), as a monthly leak detection method; and
(b) a liquid-tight tank top sump where the product piping exits the tank.
(2) Any pressurized product piping regulated under this chapter that is installed or replaced must:
(a) employ secondary containment;
(b) terminate in a liquid tight sump at each end. The sumps must:
(i) be liquid-tight on their sides, bottom, and at any penetrations;
(ii) be compatible with the substance conveyed by the piping; and
(iii) allow for visual inspection and access to the components in the containment system and/or otherwise allow the system to be monitored; and
(c) employ approved continuous interstitial monitoring, as described in ARM 17.56.407(1)(g) and (2), as a monthly leak detection method.
(3) If 50 percent or more of the length (measured from the piping terminus at the tank to the nearest point where the product is dispensed or otherwise used) or a pressurized product pipe regulated under this chapter is replaced, then the entire length of product piping must be replaced with secondarily-contained piping. The replacement of a line of product piping from a particular UST does not require the replacement of product pipes connected to other USTs.
(4) Under-dispenser containment must be installed under dispensers when:
(a) a new UST system is installed;
(b) dispensers and any associated hardware used to attach the dispenser to the underground storage tank system are replaced. Equipment necessary to connect the dispenser to the underground storage tank system includes check valves, shear valves, unburied risers or flexible connectors, or other transitional components that are underneath the dispenser and used to connect the dispenser to the underground piping;
(c) product piping is repaired or replaced at an associated dispenser island;
(d) significant modifications are made to the concrete at a dispenser island; or
(e) the department determines under-dispenser containment is necessary to meet the requirements of this rule.
(5) If under-dispenser containment is required pursuant to (1) or (4), the containment must:
(a) employ approved interstitial monitoring, as described in ARM 17.56.407(1)(g) and (2), as a monthly leak detection method;
(b) be liquid-tight on its sides, bottom, and at any penetrations;
(c) be compatible with the substance conveyed by the piping; and
(d) allow for visual inspection and access to the components in the containment system or be periodically monitored for leaks from the dispenser system.