What key document must be submitted within 30 days after a reportable release is identified?

The correct answer is the incident report, which is a fundamental requirement when a reportable release is identified. An incident report provides essential details about the release, including the time and location of the event, the substances involved, the potential impact on the environment, and the immediate response actions taken. Submitting this report within 30 days is crucial for regulatory compliance and to ensure that appropriate mitigation measures are initiated promptly.

In contrast, the other documents listed, such as a cleaning contract, insurance policy, or proof of financial responsibility, do not primarily serve the immediate need for reporting and analyzing a release. These documents may be relevant in later stages of response or in reviewing financial obligations, but the incident report is the critical document required to notify authorities and initiate investigations and remediation efforts. Properly documenting and reporting releases helps protect human health and the environment, aligning with the regulatory framework governing underground storage tanks.