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 11-5-2.7-280.70 - Temporary closure

(a) When an UST system is temporarily closed, owners and operators must notify the MDEQ and continue operation and maintenance of corrosion protection in accordance with § 280.32, and any leak detection in accordance with Rule 2.4 and Rule 2.10. Rule 2.5 and Rule 2.6 must be complied with if a release is suspected or confirmed. However, leak detection is not required as long as the UST system is empty. The UST system is empty when all materials have been removed using commonly employed practices so that no more than one (1) inch of residue remains in the system.

(b) When an UST system is temporarily closed for 3 months or more, owners and operators must also comply with the following requirements:

(c) When an UST system is temporarily closed for more than 12 months, owners and operators must permanently close the UST system if it does not meet either performance standards in § 280.20 for new UST systems or the upgrading requirements in § 280.21, except that the spill and overfill equipment requirements do not have to be met. Owners and operators must permanently close the substandard UST systems at the end of this 12-month period in accordance with §§ 280.71-280.74, unless the MDEQ provides an extension of the 12-month temporary closure period. Owners and operators must complete a site assessment in accordance with § 280.72 before such an extension can be applied for.

(d) On or before October 5, 2019, when an UST system is temporarily closed for more than 12 months and the UST system meets the performance standards in § 280.20 for new UST system or the upgrading requirements in § 280.21, owners and operators shall permanently close the UST system at the end of this 12-month period in accordance with § 280.71-280.74, or complete a site assessment in accordance with § 280.72. At the end of the 12-month period and each calendar year thereafter, the owner and operator must perform and document an UST system inspection to verify the UST system is empty (less than one inch of petroleum product is in the tank), vent lines are open and functioning, piping is securely capped, and corrosion protection is operating correctly. The records for the annual temporary closure inspection shall be made available to MDEQ upon request.