Ariz. Admin. Code § R18-12-272 - Assessing the UST Site at Closure or Change-in-service

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.

B. The requirements of this Section are satisfied if owners and operators document all of the following:

1. The UST system is monitored by one of the external release detection methods described in R18-12-243(E) or (F) ,

2. The release detection system has been operated in accordance with the requirements of R18-12-240 ,

3. The release detection system indicates no releases have occurred.

Notes

Ariz. Admin. Code § R18-12-272

Adopted effective July 30, 1996 (Supp. 96-3). Amended by final rulemaking at 25 A.A.R. 3123, effective 1/1/2020.