PURPOSE: This rule outlines the options for leak detection at petroleum underground storage tanks.

1. (1) Owners and operators of petroleum underground storage tanks (UST) systems must provide release detection for tanks and piping as follows:

   1. (A) Tanks. Tanks must be monitored at least every thirty (30) days for releases using one (1) of the methods listed in 10 CSR 20- 10.043(1)(D)—(H) except that—

      1. 1. UST systems that meet new or

upgraded standards in 10 CSR 20-10.020 or 10 CSR 20-10.021 and the monthly inventory control requirements in 10 CSR 20- 10.043(1)(A) or (B) may use tank tightness testing (10 CSR 20-10.043(1)(C)) at least every five (5) years until December 22, 1998 or until ten (10) years after the tank is installed or upgraded under 10 CSR 20- 10.021(2), whichever is later;

1. 2. UST systems that do not meet the

performance standards in 10 CSR 20-10.020 or 10 CSR 20-10.021 may use monthly inventory controls (10 CSR 20-10.043(1)(A) or (B)) and annual tank tightness testing (10 CSR 20-10.043(1)(C)) until December 22, 1998, when the tank must be upgraded under 10 CSR 20-10.021 or permanently closed under 10 CSR 20-10.071; and

1. 3. Tanks with capacity of five hundred

fifty (550) gallons or less may use manual tank gauging (10 CSR 20-10.043(1)(B)); and

1. (B) Piping. Underground piping that routinely contains regulated substances must be monitored for releases in a manner that meets one (1) of the following requirements:

   1. 1. Pressurized piping. Underground pip-

ing that conveys regulated substances under pressure must—

1. A. Be equipped with an automatic

line leak detector in 10 CSR 20- 10.044(1)(A); and

1. B. Have an annual line tightness test

conducted in accordance with 10 CSR 20- 10.044(1)(B) or have monthly monitoring conducted in accordance with 10 CSR 20- 10.044(1)(C); and

1. 2. Suction piping. Underground piping

that conveys regulated substances under suction must either have a line tightness test conducted at least every three (3) years and in accordance with 10 CSR 20-10.044(1)(B) or use a monthly monitoring method conducted in accordance with 10 CSR 20-10.044(1)(C). No release detection is required for suction piping that is designed and constructed to meet the following standards:

1. A. The below-grade piping operates

at less than atmospheric pressure;

1. B. The below-grade piping is sloped

so that the contents of the pipe will drain back into the storage tank if the suction is released;

1. C. Only one (1) check valve is includ-

ed in each suction line;

1. D. The check valve is located direct-

ly below and as close as practical to the suction pump; and

1. E. A method is provided that allows

compliance with subparagraphs (1)(B)2.A.— D. of this rule to be readily determined (for example, the check valve can be visually inspected).

AUTHORITY: sections 319.107, RSMo (Cum. Supp. 1989) and 644.026, RSMo (Cum. Supp. 1993).* Original rule filed April 2, 1990, effective Sept. 28, 1990. *Original authority: 319.107, RSMo (1989) and 644.026, RSMo (1972), amended 1973, 1987, 1993.