40 CFR § 280.71 - Permanent closure and changes-in-service.
(a) At least 30 days before beginning either permanent closure or a change-in-service under paragraphs (b) and (c) of this section, or within another reasonable time period determined by the implementing agency, owners and operators must notify the implementing agency of their intent to permanently close or make the change-in-service, unless such action is in response to corrective action. The required assessment of the excavation zone under § 280.72 must be performed after notifying the implementing agency but before completion of the permanent closure or a change-in-service.
(b) To permanently close a tank, owners and operators must empty and clean it by removing all liquids and accumulated sludges. All tanks taken out of service permanently must: be removed from the ground, filled with an inert solid material, or closed in place in a manner approved by the implementing agency.
(c) Continued use of an UST system to store a non-regulated substance is considered 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 accordance with § 280.72.
The following cleaning and closure procedures may be used to comply with this section:
(A) American Petroleum Institute Recommended Practice RP 1604, “Closure of Underground Petroleum Storage Tanks”;
(C) American Petroleum Institute Recommended Practice 2016, “Guidelines and Procedures for Entering and Cleaning Petroleum Storage Tanks”;
(D) American Petroleum Institute Recommended Practice RP 1631, “Interior Lining and Periodic Inspection of Underground Storage Tanks,” may be used as guidance for compliance with this section;
(F) National Institute for Occupational Safety and Health Publication 80–106, “Criteria for a Recommended Standard . . . Working in Confined Space” may be used as guidance for conducting safe closure procedures at some hazardous substance tanks.