1. Before completion of a permanent closure or a change in service, owners and operators 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, owners and operators shall consider the method of closure, the nature of the stored substance, the type of backfill, the depth to ground water, and other factors appropriate for identifying the presence of a release.

2. If contaminated soil, contaminated ground water, or free product as a liquid or vapor is discovered under subsection 1, or by any other manner, owners and operators shall begin corrective action in accordance with sections 33.1-13-01-09 through 33.1-13-01-14.

3. If an aboveground storage tank system is permanently closed before April 1, 2026, and the department determines a release from the aboveground storage tank may pose a current or potential threat to human health and the environment, the department may require the owner or operator to assess the excavation zone and close the aboveground storage tank system in accordance with sections 33.1-13-01-08 through 33.1-13-01-14.