Release investigation and confirmation steps

Unless corrective action is initiated in accordance with sections 33.1-24-08-50 through 33.1-24-08-57, owners and operators must immediately investigate and confirm all suspected releases of regulated substances requiring reporting under section 33.1-24-08-40 within seven days, or another reasonable time period specified by the department, using either the following steps or another procedure approved by the department: 1. System test. Owners and operators must conduct tests (according to the requirements for tightness testing in subsection 3 of section 33.1-24-08-33 and subsection 2 of section 33.1-24-08-34 or, as appropriate, secondary containment testing described in subsection 4 of section 33.1-24-08-23). a. The test must determine whether: (1) A leak exists in that portion of the tank that routinely contains product, or the attached delivery piping; or (2) A breach of either wall of the secondary containment has occurred. b. If the system test confirms a leak into the interstice or a release, owners and operators must repair, replace, upgrade, or close the underground storage tank system, and begin corrective action in accordance with sections 33.1-24-08-50 through 33.1-24-08-57 if the test results for the system, tank, or delivery piping indicate that a release exists. c. Further investigation is not required if the test results for the system, tank, and delivery piping do not indicate that a release exists and if environmental contamination is not the basis for suspecting a release. d. Owners and operators must conduct a site check as described in subsection 2 if the test results for the system, tank, and delivery piping do not indicate that a release exists but environmental contamination is the basis for suspecting a release. 2. Site check. Owners and operators must measure for the presence of a release where contamination is most likely to be present at the underground storage tank site. In selecting sample types, sample locations, and measurement methods, owners and operators must 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. a. If the test results for the excavation zone or the underground storage tank site indicate that a release has occurred, owners and operators must begin corrective action in accordance with sections 33.1-24-08-50 through 33.1-24-08-57. b. If the test results for the excavation zone or the underground storage tank site do not indicate that a release has occurred, further investigation is not required.