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)
Appendix 11-5-2-280.4 - GUIDELINES FOR THE PERMANENT CLOSURE OF PETROLEUM UNDERGROUND STORAGE TANK SYSTEMS
Section 11-5-2-280.4-5 - SAMPLING LOCATIONS FOR DISPENSER ISLANDS & PIPING
Section 11-5-2-280.4-5.3 - Piping Trenches
Section 11-5-2-280.4-5.3.2 - Removal of Piping - Sidewall Contamination Apparent

If any of the sidewalls of the piping trench excavation appear to be contaminated, the sidewalls must be sampled. Samples must be collected from the areas of the sidewalls that appear to be the most contaminated. However, sampling must be conducted so that no more than 50 feet exists between any two sampling points.

If the site conditions are such that the sidewalls are the appropriate locations for all samples, at least one of the samples must be collected from the floor of the piping trench excavation where the most contamination appears to be present. The sample must be collected at a depth of at least one foot below the piping trench and into the native soil. If no area of the floor appears contaminated or it appears uniformly contaminated, the sample must be collected at the midpoint of the piping trench.