PURPOSE: This rule defines the underground storage tanks that are subject to the requirements of this chapter. This rule contains the technical standards for underground storage tanks. This rule is designed specifically to protect the quality of groundwater in the state as well as to protect human health and the overall quality of the environment. This rule is promulgated on the authority of sections 319.100–319.137, RSMo, and, as directed by this law, are based upon federal rules 40 CFR 280.10–40 CFR 280.74.

1. (1) The requirements of this chapter apply to all owners and operators of an underground storage tank (UST) system as defined in 10 CSR 26-2.012, except as otherwise provided in sections (2)–(4) of this rule. Any UST system listed in section (3) of this rule must meet the requirements of 10 CSR 26-2.011.

2. (2) The following UST systems are excluded from the requirements of this chapter:

   1. (A) Any UST system holding hazardous wastes listed or identified in the Missouri Hazardous Waste Management Law, sections 260.350–260.434, RSMo, and the rules promulgated thereunder or a mixture of hazardous waste and other regulated substances, except for used oil as defined in 10 CSR 25- 11.279;
   2. (B) Any wastewater treatment tank system that is part of a wastewater treatment facility regulated under Section 402 or 307(b) of the Clean Water Act (33 U.S.C. 1251);
   3. (C) Equipment or machinery that contains regulated substances for operational purposes such as hydraulic lift tanks and electrical equipment tanks;
   4. (D) Any UST system whose capacity is one hundred ten (110) gallons or less;
   5. (E) Any UST system that is installed within a vault, if all exterior surface areas of the tank may be visually inspected without removal of backfill, gravel, sand, or other fill material;
   6. (F) Any UST system that contains a de minimis concentration of regulated substances; and
   7. (G) Any emergency spill or overflow containment UST system that is expeditiously emptied after use.

3. (3) Partial Exclusions. Rules 10 CSR 26- 2.020–10 CSR 26-2.053 and closure requirements in 10 CSR 26-2.060–10 CSR 26-2.064 do not apply to any of the following types of UST systems:

   1. (A) Wastewater treatment tank systems not covered in subsection (2)(B) above;
   2. (B) Any UST systems containing radioactive material that are regulated under the Atomic Energy Act of 1954 (42 U.S.C. 2011 and following);
   3. (C) Any UST system that is part of an emergency generator system at nuclear power generation facilities licensed by the Nuclear Regulatory Commission and subject to the Nuclear Regulatory Commission requirements regarding design and quality criteria, including, but not limited to, 10 CFR Part 50;
   4. (D) Aboveground tanks associated with airport hydrant fuel distribution systems; and
   5. (E) Aboveground tanks associated with field-constructed tanks.

4. (4) Previously deferred UST systems. Previously deferred airport hydrant fuel distribution systems, tank systems, and field constructed tanks systems must meet one (1) of the following options for compliance:

   1. (A) Option 1. Owners and operators must document that the previously deferred UST is appropriate for continued use by providing proof of compliance with 10 CSR 26-2.020 through 10 CSR 26-2.048, in accordance with the timeframes allowed in 10 CSR 26- 2.013; or
   2. (B) Option 2. Permanent closure of the UST system no later than December 31, 2019, in accordance with 10 CSR 26-2.060 through 10 CSR 26-2.064.
   3. (C) New UST systems installed after July 1, 2017, must meet all requirements at installation.

AUTHORITY: sections 319.100, 319.105, 319.107, 319.109, 319.111, 319.114, and 319.137, RSMo 2016.* This rule originally filed as 10 CSR 20-10.010. Original rule filed April 2, 1990, effective Sept. 28, 1990. Amended: Filed Jan. 2, 1996, effective Aug. 30, 1996. Moved and amended: Filed April 15, 2011, effective Dec. 30, 2011. Amended: Filed Aug. 15, 2016, effective May 30, 2017. *Original authority: 319.100, RSMo 1989, amended 1991, 1993, 1996, 1998; 319.105, RSMo 1989; 319.107, RSMo 1989, amended 1994; 319.109, RSMo 1989, amended 1995, 2004, 2008; 319.111, RSMo 1989; 319.114, RSMo 1989, amended 2016; and 319.137, RSMo 1989, amended 1993, 1995, 2004.