Assessing the site at closure or change in service

1. Before permanent closure or a change in service is completed, 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 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. The requirements of this section are satisfied if one of the external release detection methods allowed in subsections 5 and 6 of section 33.1-24-08-33 is operating in accordance with the requirements in section 33.1-24-08-33 at the time of closure, and indicates no release has occurred. 2. If contaminated soils, contaminated ground water, or free product as a liquid or vapor is discovered under subsection 1, or by any other manner, owners and operators must begin corrective action in accordance with sections 33.1-24-08-50 through 33.1-24-08-57.