(1) Except as provided in (3), owners and operators of petroleum UST systems shall provide release detection for tanks and piping as follows:

(a) tanks must be monitored at least every 30 days for releases using one of the methods listed in ARM 17.56.407(1)(d) through (h) except that:

(i) UST systems that meet the performance standards in ARM 17.56.201 or 17.56.202, and the monthly inventory control requirements in ARM 17.56.407(1)(a) or (b), may use tank tightness testing (conducted in accordance with ARM 17.56.407(1)(c)) at least every five years until December 22, 1998, or until ten years after the tank is installed or upgraded under ARM 17.56.202(2), whichever is later;

(ii) UST systems that do not meet the performance standards in ARM 17.56.201 or 17.56.202 may use monthly inventory controls (conducted in accordance with ARM 17.56.407(1)(a) or (b)) and annual tank tightness testing (conducted in accordance with ARM 17.56.407(1)(c)) until December 22, 1998, when the tank must be upgraded under ARM 17.56.202 or permanently closed under ARM 17.56.702;

(iii) tanks with capacity of 550 gallons or less may use weekly tank gauging (conducted in accordance with ARM 17.56.407(1)(b)); and

(iv) farm or residential tanks of 1,100 gallons or less capacity used for storing motor fuel for noncommercial purposes, a tank of 1,100 gallons or less capacity used for storing heating oil for consumptive use on the premises where stored, and emergency power generator tanks with capacities of 1,100 gallons or less capacity may use yearly tank gauging (conducted in accordance with ARM 17.56.407(1)(b)); and

(b) underground piping that routinely contains regulated substances must be monitored for releases in a manner that meets one of the following requirements:

(i) underground piping that conveys regulated substances under pressure must:

(A) be equipped with an automatic line leak detector conducted in accordance with ARM 17.56.408(1)(a); and

(B) have an annual line tightness test conducted in accordance with ARM 17.56.408(1)(b) or have monthly monitoring conducted in accordance with ARM 17.56.408(1)(c); and

(ii) underground piping that conveys regulated substances under suction must either have a line tightness test conducted at least every three years and in accordance with ARM 17.56.408(1)(b), or use a monthly monitoring method conducted in accordance with ARM 17.56.408(1)(c). No release detection is required for suction piping that is designed and constructed to meet the following standards:

(A) the below-grade piping operates at less than atmospheric pressure;

(B) the below-grade piping is closed so that the contents of the pipe will drain back into the storage tank if the suction is released;

(C) only one check valve is included in each suction line;

(D) the check valve is located directly below and as close as practical to the suction pump; and

(E) a method is provided that allows compliance with (1)(b)(ii)(B) through (D) to be readily determined;

(iii) underground piping connected to heating oil tanks with a capacity of 660 gallons or less is exempt from the requirements of (1)(b)(i) and (ii) provided that:

(A) the new primary underground piping has secondary containment;

(B) liquid released into the interstitial space will move not more than 20 feet before being detected in a standpipe or sump;

(C) the interstice is visually monitored for released liquid once every 30 days; and

(D) the test results are maintained for at least one year; and

(iv) new underground piping connected to underground heating oil tanks with a capacity of 660 gallons or less shall slope back towards tanks that do not have foot valves.

(2) All leak testing results required by this rule must be observed by the owner, operator, or facility employee and the owner or operator shall document and retain the results.

(3) Terminal piping is exempt from the requirements of ARM 17.58.204(2) and (3), 17.56.304(3)(f)(i), 17.56.408(1)(a) through (d), 17.56.504(1)(a), and 17.56.701(4)(b)(ii) and (d)(ii). The department may exempt other associated piping on a case-by-case basis, if the department determines the exemption would not cause harm to human health or the environment.

(4) The exempt piping referenced in (2) must be annually leak tested using:

(a) the procedures described in American Petroleum Institute Recommended Practice 1110, "Recommended Practice for Pressure Testing of Steel Pipelines for the Transportation of Gas, Petroleum Gas, Hazardous Liquids, Highly Volatile Liquids or Carbon Dioxide," with the following exceptions:

(i) the minimum leak test pressure ratios may not be less than 1.0;

(ii) the leak test duration may not be less than one hour; and

(iii) leak acceptance criteria must be based on 5% decrease in pressure of the pipeline segment during the test period; or

(b) another leak test procedure approved by the department.

(5) The department adopts and incorporates by reference the version in effect on July 1, 2008, of American Petroleum Institute Recommended Practice 1110, "Recommended Practice for Pressure Testing of Steel Pipelines for the Transportation of Gas, Petroleum Gas, Hazardous Liquids, Highly Volatile Liquids or Carbon Dioxide," which sets forth guidelines for pressure testing steel pipelines for the transportation of gas, petroleum gas, hazardous liquids, highly volatile liquids, or carbon dioxide, a copy of which may be obtained from Global Engineering Documents, 15 Inverness Way East, M/S C303B, Englewood, CO 80112-5776, (303) 397-7956.