If a release from an aboveground storage tank is confirmed under section 33.1-13-01-14 or is identified in any other manner, an owner or operator shall perform the following actions:

1. Take immediate action to prevent any further release of the liquid fuel into the environment, including removing as much of the liquid fuel from the aboveground storage tank system as is necessary to prevent further release to the environment;

2. Identify and mitigate fire, explosion, and vapor hazards posed by vapors or free product that have entered into subsurface structures, such as sewers or basements, and remove any flammable products in a safe and competent manner to prevent fires or explosions.

3. Unless otherwise directed by the department, perform the following abatement measures: a. Remedy hazards posed by contaminated soils that are excavated or exposed as a result of release confirmation, site investigation, abatement, or corrective action activities. If remedies include treatment or disposal of soils, an owner or operator shall comply with applicable state and local requirements; b. Measure for the presence of a release where contamination is most likely to be present at the aboveground storage tank site, unless the presence and source of the release have been confirmed in accordance with the site check required by subsection 2 of section 33.1-13-01-12 or the closure site assessment in subsection 1 of section 33.1-13-01-09. In selecting sample types and locations and measurement methods, the owner or operator shall consider the nature of the stored substance, the type of backfill, depth to ground water, and other factors as appropriate for identifying the presence and source of the release; and c. Determine the presence of free product, and begin free product removal as soon as practicable in a manner that: (1) Minimizes the spread of contamination into previously uncontaminated zones by using recovery and disposal techniques appropriate to the hydrogeologic conditions at the site; and (2) Properly treats, discharges, or disposes of recovery byproducts in compliance with applicable local, state, and federal regulations; d. Determine the horizontal and vertical extent of contamination.