PURPOSE: This rule outlines the standards for leak detection on hazardous substance underground storage tanks.

1. (1) Owners and operators of in-use hazardous substance underground storage tank (UST) systems must use a release detection method that meets the requirements of 10 CSR 26- 2.041 and 10 CSR 26-2.043 subsection (1)(H), except for the electronic monitoring 10 CSR 26-2

requirement in 10 CSR 26-2.043 paragraph (1)(H)2. with approval from the department.

1. (2) In addition, all in-use hazardous substance USTs must meet the following requirements:

   1. (A) Secondary containment systems must be designed, constructed, and installed to—

      1. 1. Contain regulated substances released

from the tank system until they are detected and removed;

1. 2. Prevent the release of regulated sub-

stances to the environment at any time during the operational life of the UST system; and

1. 3. Be checked for evidence of a release

at least every thirty (30) days;

1. (B) Double-walled tanks must be designed, constructed, and installed to—

   1. 1. Contain a release from any portion of

the inner tank within the outer wall; and

1. 2. Detect the failure of the inner wall;

2. (C) External liners (including vaults) must be designed, constructed, and installed to—

   1. 1. Contain one hundred percent (100%)

of the capacity of the largest tank within its boundary;

1. 2. Prevent the interference of precipita-

tion or groundwater intrusion with the ability to contain or detect a release of regulated substances; and

1. 3. Surround the tank completely (that is,

it is capable of preventing lateral as well as vertical migration of regulated substances);

1. (D) Underground piping must be equipped with secondary containment that satisfies the requirements of subsection (2)(A) of this rule (for example, trench liners, jacketing of double-walled pipe). In addition, underground piping that conveys regulated substances under pressure must be equipped with an automatic line leak detector in 10 CSR 26- 2.044(1)(A); and

2. (E) Other methods of release detection may be used if owners and operators—

   1. 1. Demonstrate to the department that

an alternative method can detect a release of the stored substance as effectively as any of the methods allowed in 10 CSR 26- 2.043(1)(B)–(I) can detect a release of petroleum;

1. 2. Provide information to the depart-

ment on effective corrective action technologies, health risks, and chemical and physical properties of the stored substance and the characteristics of the UST site; and

1. 3. Obtain approval from the department

to use the alternate release detection method before the installation and operation of the new UST system.

1. (3) All new or replaced hazardous substance UST systems installed after July 1, 2017, must also comply with the containment sump testing requirements in 10 CSR 26-2.035.

AUTHORITY: sections 319.105, 319.107, and 319.137, RSMo 2016.* This rule originally filed as 10 CSR 20-10.042. 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.