(1)  Any UST that is replaced or installed 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;

(b)  under-dispenser containment that provides access; and

(c)  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 over 50% 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 product piping are replaced;

(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 and/or allow the system to be monitored.