Within twenty-four hours of identifying or being notified by another person of any of the following conditions, owners and operators of UST systems must report a suspected release to the department and initiate an investigation of the suspected release in accordance with WAC 173-360A-0720:

(1) Presence of released regulated substances at the UST facility or in the surrounding area (such as the presence of free product or its constituents or vapors in soils, basements, sewer or utility lines, groundwater, or surface water);

(2) Unusual operating conditions (such as the erratic behavior of product dispensing equipment, the sudden loss of regulated substances from an UST system, the unexplained presence of water in a tank, or the presence of liquid in the interstitial space of a secondarily contained UST system), unless:

(a) The UST system component is found not to be releasing regulated substances to the environment;

(b) Any defective UST system component is immediately repaired in accordance with WAC 173-360A-0490 or replaced in accordance with WAC 173-360A-0300; and

(c) For secondarily contained UST systems, any liquid in the interstitial space not used as part of the interstitial monitoring method (for example, brine) is immediately removed; or

(3) Monitoring results or alarms from a release detection method required under Part 6 of this chapter indicate that a release may have occurred, unless:

(a) The alarm was investigated and determined to be a nonrelease event (for example, alarm caused by power surge or filling the tank during release detection testing);

(b) The release detection equipment is found to be defective, and either:

(i) The defective equipment is immediately repaired or recalibrated in accordance with WAC 173-360A-0490 or replaced in accordance with WAC 173-360A-0300, and additional monitoring does not confirm the initial result; or

(ii) Another applicable release detection method is used and additional monitoring does not confirm the initial result;

(c) In the case of inventory control (WAC 173-360A-0620), a second month of data does not confirm the initial result. However, owners and operators must immediately investigate all larger-than-normal or reoccurring variations in inventory control results, and report such variations if they are unaccounted for, without waiting to obtain a second month of data; or

(d) In the case of interstitial monitoring (WAC 173-360A-0655):

(i) The leak is contained in the secondary containment;

(ii) Any liquid in the interstitial space not used as part of the interstitial monitoring method (for example, brine) is immediately removed; and

(iii) Any defective UST system component is immediately repaired in accordance with WAC 173-360A-0490 or replaced in accordance with WAC 173-360A-0300.