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 that are in use 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 26- 2.043(1)(B)–(I), except that—

      1. 1. UST systems that meet standards in

10 CSR 26-2.020 or 10 CSR 26-2.021 and the monthly inventory control requirements in 10 CSR 26-2.043(1)(A) may use tank tightness testing (10 CSR 26-2.043(1)(D)) 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 26- 2.021(3), whichever is later;

1. 2. Tanks with a capacity of two thousand

(2,000) gallons or less may use manual tank gauging (10 CSR 26-2.043(1)(C));

1. 3. Field-constructed tanks greater than

fifty thousand (50,000) gallons may use the alternative release detection requirements in 10 CSR 26-2.046;

1. 4. Groundwater monitoring (10 CSR 26-

2.043 subsection (1)(G)) will no longer be valid to monitor for releases after July 1, 2020;

1. 5. Vapor monitoring (10 CSR 26-2.043

subsection (l)(F)) may not be used after July 1, 2020, as a release detection method unless it is used with an added tracer chemical and listed by the National Work Group on Leak Detection Evaluations as a tank tightness test; and

1. 6. Tanks installed after July 1, 2017,

must be monitored for leaks at least every thirty (30) days in accordance with 10 CSR 26-2.043(1)(H);

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 26-2.044(1)(A);

1. B. Have an annual line tightness test

conducted in accordance with 10 CSR 26- 2.044(1)(B) or have monthly monitoring conducted in accordance with 10 CSR 26- 2.044(1)(C); and

1. C. New or replaced piping installed

after July 1, 2017, must be monitored for releases at least every thirty (30) days in accordance with 10 CSR 26-2.043 subsection (1)(H);

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 26-2.044(1)(B) or use a monthly monitoring method conducted in accordance with 10 CSR 26-2.044(1)(C). New or replaced piping installed after July 1, 2017, must be monitored for releases at least every thirty (30) days in accordance with 10 CSR 26-2.043 subsection (1)(H). 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 directly

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); and

1. 3. Gravity piping and remote fill piping

are exempt from the piping line leak detection requirements in this section; and

1. 4. Underground bulk piping associated

with airport hydrant fuel distribution systems and field-constructed tanks must meet one (1) of the following release detection requirements:

1. A. The requirements in subsection

1. (B) of this section; or

   1. B. The alternative release detection

requirements in 10 CSR 26-2.047;

1. C. Underground bulk piping installed

after July 1, 2017, must meet the requirements in paragraph 1. or 2. of this subsection;

1. 5. Except that—

   1. A. Groundwater monitoring (10 CSR

26-2.043 subsection (l)(G)) will no longer be valid to monitor for releases after July 1, 2020; and

1. B. Vapor monitoring (10 CSR 26-

2.043 subsection (l)(F)) may not be used after July 1, 2020, as a release detection method unless it is used with an added tracer chemical and listed by the National Work Group on Leak Detection Evaluations as a tightness test. (2) High-throughput Facilities. In addition to the requirements outlined in section (1) of this rule, any owner of a tank or a multi-tank connected or manifolded system that dispenses more than eight hundred thousand (800,000) gallons of any regulated substance in one (1) calendar month must use at least one (1) of the following tank system release detection methods:

1. (A) Continuous, electronic interstitial monitoring for both tank and piping systems, in accordance with 10 CSR 26-2.043(1)(H), documenting passing readings at least once every thirty (30) days; or
2. (B) Vapor monitoring, including introduced chemical marker monitoring, listed by the National Work Group on Leak Detection Evaluations (NWGLDE) for the substance stored at least once every fifteen (15) days. To obtain copies of equipment listings, contact the National Work Group on Leak Detection Evaluations, www.nwglde.org; or
3. (C) Continuous in-tank release detection, which must include continual reconciliation of tank system inventory. Standard statistical inventory control is not acceptable. The method used must meet criteria established by the National Work Group on Leak Detection Evaluations (NWGLDE) for continuous in-tank leak detection methods. To obtain copies of equipment listings, contact the National Work Group on Leak Detection Evaluations, www.nwglde.org; or
4. (D) Another method approved by the department specifically for high-throughput UST systems.

AUTHORITY: sections 319.105, 319.107, and 319.137, RSMo 2016.* This rule originally filed as 10 CSR 20-10.041. 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.