Mississippi Administrative Code
Title 11 - Mississippi Department of Environmental Quality
Part 5 - Underground Storage Tank Regulations
Chapter 2 - Mississippi Commission on Environmental Quality Underground Storage Tanks Regulations Technical Standards and Corrective Action Requirements for Owners and Operators of Underground Storage Tanks (UST) (Adopted March 22, 1989; Amended August 25, 2011, Last Amended August 23, 2018)
Rule 11-5-2.7 - Out-of-Service UST Systems and Closure
Section 11-5-2.7-280.71 - 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 rule, or within another reasonable time period determined by the MDEQ, owners and operators must notify the MDEQ 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 MDEQ but before completion of the permanent closure or a change-in-service.

(b) To permanently close a tank system, owners and operators must empty and clean it by removing all liquids and accumulated sludges from the tank system. All tank systems taken out of service permanently must also be either removed from the ground or filled with an inert solid material.

(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.