(1) At least 30 days before beginning either permanent closure or a change in service under (2) and (3), owners and operators shall notify the department and the implementing agency, in writing, of their intent to permanently close or make the change in service, unless such action is in response to corrective action already noticed to the department under subchapter 6. The required assessment of the excavation zone under ARM 17.56.703 must be performed after notifying the department and the implementing agency but before completion of the permanent closure or a change in service.

(2) To permanently close a tank or connected piping or both, owners and operators shall empty and clean it by removing all liquids and accumulated sludges. All tanks, connected piping, or both, taken out of service permanently must also be either removed from the ground or, when approved by the department, filled with an inert solid material.

(3) Continued use of an UST system to store a nonregulated substance is considered a change in service. Before a change in service, owners and operators shall empty and clean the UST system by removing all liquid, accumulated sludge, and all combustible and flammable vapors and conduct a site assessment in accordance with ARM 17.56.703.

(4) The cleaning and closure procedures in (5) must be used to comply with this rule.

(5) The department adopts and incorporates by reference the version in effect on July 1, 2006, of the following standards, specifications, and publications:

(a) American Petroleum Institute Recommended Practice 1604, "Removal and Disposal of Used Underground Petroleum Storage Tanks," which sets forth closure practices for UST systems, a copy of which may be obtained from API Publications Department, 1220 L Street NW, Washington, DC 20005, (202) 682-8375;

(b) American Petroleum Institute Publication 2015, "Cleaning Petroleum Storage Tanks," which sets forth cleaning standards for UST tanks, a copy of which may be obtained from API Publications Department, 1220 L Street NW, Washington, DC 20005, (202) 682-8375;

(c) American Petroleum Institute Recommended Practice 1631, "Interior Lining of Underground Storage Tanks," which sets forth entrance standards for UST tanks, a copy of which may be obtained from API Publications Department, 1220 L Street NW, Washington, DC 20005, (202) 682-8375; and

(d) The National Institute for Occupational Safety and Health publication No. 80-106, "Criteria for a Recommended Standard: Working in Confined Space," which sets forth standards for working inside an UST tank, a copy of which may be obtained from Superintendent of Documents, Government Printing Office, Washington, DC 20402, (202) 783-3238.