PURPOSE: This rule describes the requirements of leak detection for the piping on underground storage tanks.

1. (1) Each method of release detection for piping used to meet the requirements of release detection for underground storage tanks (USTs) in 10 CSR 26-2.041 must be conducted in the following manner:

   1. (A) Automatic Line Leak Detectors. Methods which alert the operator to the presence of a leak by restricting or shutting off the flow of regulated substances through piping or triggering an audible or visual alarm may be used only if they detect leaks of three

2. (3) gallons per hour at ten (10) pounds per square-inch line pressure within one (1) hour and are listed by the National Work Group on Leak Detection Evaluations. To obtain copies of equipment listings, contact the National Work Group on Leak Detection Evaluations, www.nwglde.org. A test of the operation of the leak detector must be conducted at least annually. The annual test must be conducted in accordance with the manufacturer’s approved testing procedures and simulate a leak of at least three (3) gallons per hour at ten (10) pounds per square inch pressure, or equivalent, in the system under normal operating conditions.

   1. 1. Line leak detectors must monitor all

pressurized piping, including pressurized piping beyond the first or master dispenser but not including other piping above the shear valve inside the dispenser or dispenser hoses to the nozzle;

1. (B) Line Tightness Testing. A periodic test of piping may be conducted only if it can detect a one-tenth- (0.1-) gallon-per-hour leak rate at one and one-half (1.5) times the operating pressure;
2. (C) Applicable Tank Methods. Any of the methods in 10 CSR 26-2.043(1)(B) and (F)-

1. (I) may be used if they are designed to detect a release from any portion of the underground piping that routinely contains regulated substances except—

   1. 1. Owners and operators of piping asso-

ciated with field-constructed tanks greater than fifty thousand (50,000) gallons or airport hydrant fuel distribution system tanks may comply with 10 CSR 26-2.074 in lieu of the methods of piping leak detection in this rule; and

1. (D) Emergency Generator Tanks. For a tank that stores fuel solely for use by an emergency generator, or a tank that stores fuel for an emergency generator and heating oil for consumptive use on the premises where stored, interstitial line monitoring with sump sensors, an alarm, and secondary containment may be used on pressurized lines in lieu of the automatic line leak detector, required in 10 CSR 26-2.041 and subsection (1)(A) of this rule.

AUTHORITY: sections 319.105, 319.107, and 319.137, RSMo 2016.* This rule originally filed as 10 CSR 20-10.044. Original rule filed April 2, 1990, effective Sept. 28, 1990. Moved and amended: Filed April 15, 2011, effective Dec. 30, 2011. Amended: Filed Aug. 15, 2016, effective May 30, 2017. *Original authority: 319.105, RSMo 1989; 319.107, RSMo 1989, amended 1994; and 319.137, RSMo 1989, amended 1993, 1995, 2004.