PURPOSE: This rule contains the requirements for permanent closure of underground storage tanks as well as for converting underground storage tanks to an unregulated use.

1. (1) Owners and operators must notify the department in writing, on forms provided by the department, at least thirty (30) days before beginning either permanent closure or a change in service of an underground storage tank (UST) in sections (2) and (3) of this rule or within another reasonable time period determined by the department, unless this action is in response to corrective action. The required assessment of the excavation zone under 10 CSR 20-10.072 must be performed after notifying the department but before completion of the permanent closure or a change in service.
2. (2) To permanently close a tank, owners and operators must empty and clean it by removing all liquids and accumulated sludges. Liquids and sludges shall be managed in accordance with state and federal regulations. All tanks taken out of service permanently must also be either removed from the ground or filled with an inert solid material.
3. (3) Continued use of a UST system to store a nonregulated substance is a change in service. Before a change in service, owners and operators must empty and clean the tank by removing all liquid and accumulated sludge and conduct a site assessment in 10 CSR 20- 10.072.

4. (4) Owners and operators shall follow a written procedure. To comply with this rule, the department’s UST Closure Guidance Document may be used as a written procedure. It may be supplemented with the following cleaning and closure procedures:

   1. (A) American Petroleum Institute Recommended Practice 1604, Removal and Disposal of Used Underground Petroleum Storage Tanks;
   2. (B) American Petroleum Institute Publication 2015, Cleaning Petroleum Storage Tanks;
   3. (C) American Petroleum Institute Recommended Practice 1631, Interior Lining of Underground Storage Tanks; and
   4. (D) Owners and operators may use other written procedures with prior written approval of the department.

AUTHORITY: sections 319.111, RSMo Supp. 1994 and 644.026, RSMo Supp. 1998.* Original rule filed April 2, 1990, effective Sept. 28, 1990. Amended: Filed Aug. 3, 1993, effective April 9, 1994. Amended: Filed April 1, 1999, effective March 30, 2000. *Original authority: 319.111, RSMo 1989 and 644.026, RSMo 1972, amended 1973, 1987, 1993, 1995.