Arizona Administrative Code › Title 18 - ENVIRONMENTAL QUALITY › Chapter 12 - DEPARTMENT OF ENVIRONMENTAL QUALITY - UNDERGROUND STORAGE TANKS › Article 2 - TECHNICAL REQUIREMENTS › Section R18-12-272 - Assessing the UST Site at Closure or Change-in-service

Current through Register Vol. 30, No. 28, July 12, 2024
A. Before permanent closure or a
				change-in-service is completed, owners and operators shall measure for the
				presence of a release at the UST site by taking samples for laboratory
				analysis. Samples shall be obtained in the areas where contamination would most
				likely occur, or where stained soils, odors, vapors, free product, or other
				evidence indicates that a release may have occurred. Measurement for presence
				of a release shall be performed according to all of the following:
1. Owners and operators shall document the
				environmental condition of the UST site and the presence or absence of any
				contamination resulting from the operation of the UST system at the site
				through analyses performed on samples of native soil, and of water encountered
				during the UST closure assessment;
2. Specific locations for the required
				sampling at the UST system site shall be determined by the presence of stained
				soils, odors, vapors, free product, or other evidence indicating that a release
				may have occurred. In selecting sample types, sample locations, and measurement
				methods, owners and operators shall also consider the method of closure, the
				nature of the stored substance, the type of backfill, the depth to groundwater,
				and other factors which may identify the presence of a release. At a minimum,
				each site shall be sampled in accordance with the following:
a. If water is not present in the excavation
				at the time an UST is removed or if the UST is filled with a solid inert
				material as described in
				R18-12-271(D)(4),
				a minimum of two distinct soil samples shall be taken from native soils beneath
				each tank that has a capacity to hold more than 550 gallons. The samples shall
				be taken from beneath each end of each tank. In cases where the fill pipe or
				pump is located above the center of the tank, an additional sample shall be
				taken from beneath the center of the tank. If the capacity of the tank is 550
				gallons or less, then one sample shall be taken from native soils beneath the
				center of the tank;
b. If water is
				present above the floor of the excavation at the time an UST is removed,
				distinct samples of native soils shall be taken from the walls of the
				excavation at the soil-water interface at both ends of the tank;
c. If native soil cannot be collected in
				accordance with
				R18-12-280
				due to large clast size or induration, or if the excavation zone is constructed
				in bedrock one of the following shall be performed:
i. Samples of the UST excavation backfill
				material shall be collected from beneath the UST system in accordance with
				locations described in subsection (A)(2)(a).
ii. If the UST excavation backfill material
				cannot be sampled, the Department shall be contacted for further
				instruction.
d. If water
				is encountered during activities required under this Section, a sample of the
				water shall be collected for analysis. If a sheen or free product is observed
				on the water or in the sample, the sampling requirements of subsection (A)(2)
				do not have to be met, however, further reporting and investigation shall be
				conducted in accordance with R18-12-274;
e. If piping is permanently closed in
				accordance with
				R18-12-271(D)(2)
				distinct samples of native soil shall be collected under elbows, joints,
				fittings, dispensers and areas of corrosion. In addition, such sampling shall
				ensure that samples are collected every 20 linear feet along the piping
				trench;
f. Stockpiled excavated
				soil shall be sampled in accordance with A.R.S. Title 49, Chapter 4, Article 9,
				and the rules promulgated thereunder.
3. All required sampling shall be performed
				in accordance with
				R18-12-280.