Release investigation and confirmation

1. Whenever required by the department, an owner or operator shall determine if an aboveground storage tank system is the source of offsite impacts, including the discovery of liquid fuel, such as the presence of free product or vapors in soils, basements, sewer and utility lines, and nearby surface and drinking waters. 2. The department may require an owner or operator to use one of the following methods to investigate a release: a. System test. An owner or operator shall conduct tests according to the requirements for release detection or tightness testing sections 33.1-13-01-04 and 33.1-13-01-05. (1) The test must determine whether: (a) A leak exists in that portion of the tank or piping that routinely contains product; or (b) A breach of the secondary containment has occurred. (2) If the system test confirms a leak into the secondary containment or a release to the environment, an owner or operator shall repair, replace, upgrade, or close the aboveground storage tank system, and begin corrective action in accordance with sections 33.1-13-01-11 through 33.1-13-01-14. (3) If the test results for the aboveground storage tank system, tank, and delivery piping do not indicate that a leak exists and environmental contamination is not the basis for suspecting a release, further investigation is not required. (4) If the test results for the system, tank, and delivery piping do not indicate that a leak exists but environmental contamination is the basis for suspecting a release an owner or operator shall conduct a site check as described in subdivision b. b. Site check. An owner or operator shall measure for the presence of a release where contamination is most likely to be present at the aboveground storage tank site. In selecting sample types and locations and measurement methods, an owner or operator shall consider the nature of the stored substance, the type of initial alarm or cause for suspicion, the type of backfill, the depth of ground water, and other factors appropriate for identifying the presence and source of the release. (1) If the test results for the excavation zone or the aboveground storage tank site indicate that a release has occurred, owners and operators must begin corrective action in accordance with sections 33.1-13-01-11 through 33.1-13-01-14. (2) If the test results for the excavation zone or the aboveground storage tank site do not indicate that a release has occurred, further investigation is not required. c. Any other method approved of by the department.