What indicates that a "confirmed release" has occurred at a HOT site?

A "confirmed release" at a Heating Oil Tank (HOT) site is indicated by the observation of petroleum contamination, which can manifest as a sheen or stain in soil or groundwater. This physical evidence is critical because it directly demonstrates that petroleum products have been released from the tank or related systems into the environment. The presence of sheen or staining is a clear indicator of contamination and signifies the urgent need for assessment and remediation efforts.

While detecting a petroleum odor in the air may suggest the potential for a release, it is not definitive proof without accompanying visual evidence of contamination. A report from a third party can initiate an investigation but does not in itself confirm a release. Similarly, a visual inspection that finds no signs of contamination does not support the conclusion of a release, as the absence of evidence does not confirm that any has occurred. Therefore, the visibility of a sheen or stain is the most concrete indicator of a confirmed release at a HOT site.