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

1. (1) Owners and operators of hazardous substance underground storage tank (UST) systems must provide release detection that meets the following requirements:

   1. (A) Release detection at existing UST systems must meet the requirements for petroleum UST systems in 10 CSR 20- 10.041. By December 22, 1998, all hazardous substance UST systems must meet the release detection requirements for new systems in subsection (1)(B) of this rule;

   2. (B) Release detection at new hazardous substance UST systems must meet the following requirements:

      1. 1. Secondary containment systems must

be designed, constructed and installed to—

1. A. Contain regulated substances

released from the tank system until they are detected and removed;

1. B. Prevent the release of regulated

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

1. C. Be checked for evidence of a

release at least every thirty (30) days;

1. 2. Double-walled tanks must be

designed, constructed and installed to—

1. A. Contain a release from any portion

of the inner tank within the outer wall; and

1. B. Detect the failure of the inner wall;
2. 3. External liners (including vaults)

must be designed, constructed and installed to—

1. A. Contain one hundred percent

(100%) of the capacity of the largest tank within its boundary;

1. B. Prevent the interference of precip-

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

1. C. Surround the tank completely

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

1. 4. Underground piping must be

equipped with secondary containment that satisfies the requirements of paragraph (1)(B)1. 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 20-10.044(1)(A); and

1. 5. Other methods of release detection

may be used if owners and operators—

1. A. Demonstrate to the department

that an alternate method can detect a release of the stored substance as effectively as any of the methods allowed in 10 CSR 20- 10.043(1)(B)—(H) can detect a release of petroleum;

1. B. 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. C. Obtain approval from the depart-

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

1. (2) The provisions of 10 CSR 25-7.265(2)(J) may be used to comply with this rule.

AUTHORITY: sections 319.107, RSMo Supp. 1989 and 644.026, RSMo 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.