(1) Owners and operators must contain and immediately clean up a spill or overfill, immediately report the spill or overfill to the department and the implementing agency pursuant to (3) or by another method that ensures that a person within the Remediation Division of the department receives notice within 24 hours of the release, and must begin corrective action in accordance with subchapter 6 in the following cases:

(a) spill or overfill of petroleum that results in a release to the environment that exceeds 25 gallons, or that causes a sheen on nearby surface water; and

(b) spill or overfill of a hazardous substance that results in a release to the environment that equals or exceeds its reportable quantity under 40 CFR Part 302.

(2) Owners and operators must contain and immediately clean up a spill or overfill of petroleum that is less than 25 gallons and a spill or overfill of a hazardous substance that is less than the reportable quantity. If cleanup cannot be accomplished within 24 hours, owners and operators must immediately notify the department and the implementing agency.

(3) Telephone notification required in (1) or (2) must be made to a person in the Remediation Division of the department or to the 24-hour Disaster and Emergency Services duty officer at (406) 841-3911. Messages left on answering machines, received by facsimile, email, voice mail or other messaging device are not adequate 24-hour notice. For further assistance, the department's release reporting hotline may be reached at 1 (800) 457-0568.