40 CFR § 280.41 - Requirements for petroleum UST systems.
(i) UST systems that meet the performance standards in § 280.20 or § 280.21, and the monthly inventory control requirements in § 280.43(a) or (b), may use tank tightness testing (conducted in accordance with § 280.43(c)) at least every 5 years until 10 years after the tank was installed; and
(ii) Tanks with capacity of 550 gallons or less and tanks with a capacity of 551 to 1,000 gallons that meet the tank diameter criteria in § 280.43(b) may use manual tank gauging (conducted in accordance with § 280.43(b)).
(1) Piping installed on or before April 11, 2016 must meet one of the following:
(i) Pressurized piping. Underground piping that conveys regulated substances under pressure must:
(A) Be equipped with an automatic line leak detector conducted in accordance with § 280.44(a); and
(ii) Suction piping. Underground piping that conveys regulated substances under suction must either have a line tightness test conducted at least every 3 years and in accordance with § 280.44(b), or use a monthly monitoring method conducted in accordance with § 280.44(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;
(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 paragraphs (b)(1)(ii)(B) through (D) of this section to be readily determined.
(2) Piping installed or replaced after April 11, 2016 must meet one of the following:
(ii) Suction piping must be monitored for releases at least every 30 days in accordance with § 280.43(g). No release detection is required for suction piping that meets paragraphs (b)(1)(ii)(A) through (E) of this section.