D.C. Mun. Regs. tit. 20, r. 20-6004
The owner or operator of a petroleum UST system shall regularly monitor all underground piping that contains or conveys regulated substances for releases, in accordance with the provisions of this section.
Each method of release detection for petroleum UST system piping, except piping associated with a heating oil tank installed on or before November 12, 1993, shall meet the requirements of this section.
Underground piping that conveys pressurized regulated substances shall be equipped with an automatic line leak detector that alerts the operator to the presence of a leak by triggering an audible and visual alarm, or restricting or shutting off the flow of regulated substances through the piping.
An automatic line leak detector shall detect, within one (1) hour, leaks of three gallons per hour (3 gal/hr) at ten pounds per square inch (10 psi) line pressure.
The owner or operator of an UST shall annually test for the proper operation of the automatic line leak detector in accordance with the manufacturer's instructions.
An owner or operator of an UST with underground piping that conveys pressurized regulated substances shall conduct a line tightness test annually in accordance with § 6004.8, or use monthly monitoring methods in accordance with § 6004.10.
Except as provided in § 6004.9, an owner or operator of an UST with underground piping that conveys regulated substances under suction shall conduct a line tightness test at least once every three (3) years in accordance with § 6004.8, or use monthly monitoring methods in accordance with § 6004.10.
Periodic line tightness testing of piping shall detect a leak rate of one tenth of a gallon per hour (0.1 gal/hr) at one and one half (1.5) times the operating pressure.
No release detection is required for safe suction piping if:
Except as provided in § 6004.11, an owner or operator may conduct monthly monitoring of piping using any of the methods of release detection for tanks in §§ 6009 through 6011 if the method used is designed to detect a release from any portion of the underground piping that contains or conveys regulated substances.
The owner or operator of an UST with underground piping installed or replaced after February 8, 2007, shall check for evidence of a release from the underground piping at least once every thirty (30) days using interstitial monitoring in accordance with § 6011.
D.C. Mun. Regs. tit. 20, r. 20-6004