An owner or operator shall report a release or suspected release to the department, by telephone or online spill report form, within twenty-four hours if:

1. Released liquid fuel at the aboveground storage tank site or in the surrounding area, such as the presence of free product or vapors in soils, basements, sewer and utility lines, and nearby surface water is discovered;

2. Unusual operating conditions are observed by an owner or operator, such as the erratic behavior of product dispensing equipment, the sudden loss of product from the aboveground storage tank system, or an unexplained presence of water in the tank, unless system equipment is found to be defective, but not leaking, and is immediately repaired or replaced;

3. Monitoring results from a release detection method required under section 33.1-13-01-04 indicate a release may have occurred, unless:

a. The monitoring device is found to be defective, and is immediately repaired, recalibrated, or replaced, and additional monitoring does not confirm the initial result; or

b. In the case of inventory control, a second month of data does not confirm the initial result.

4. A release detection method operated in accordance with the performance standards in section 33.1-13-01-04 indicates a release may have occurred.

5. Any spill or overfill resulting in a release exceeds twenty-five gallons [94.64 liters] or any volume that causes a sheen on nearby surface water or threatens public health or safety.