(1) The department shall assign each confirmed petroleum release from a petroleum storage tank a unique identification number. Except as provided in (2), from the date of discovery of a confirmed release of petroleum from a petroleum storage tank at a facility, all contamination from petroleum storage tanks subsequently discovered through any investigative or corrective action in response to the previously confirmed and numbered release pursuant to subchapter 5 or 6, is considered "one release" and part of the previously confirmed and numbered release.
(2) Under the following circumstances the department shall confirm a separate release and assign another release identification number to petroleum contamination from a petroleum storage tank at a facility that has a previously confirmed and numbered release:
(a) when a separate release from a petroleum storage tank is discovered at a facility and, based on substantial evidence, the department finds the release began after the department categorized all earlier confirmed releases at the facility as resolved in accordance with ARM 17.56.607(4);
(b) when, based on substantial evidence, the department finds that there is a separate release of petroleum from a petroleum storage tank at a facility that began after any previously confirmed and numbered release was discovered; or
(c) when additional contamination from a petroleum storage tank is discovered and, based on substantial evidence, the department finds that the contamination originated from a petroleum storage tank or tanks at a different facility than the facility where the previously confirmed and numbered release occurred.
(3) For the purposes of this rule only, "facility" means any one or a combination of petroleum storage tanks that are located on contiguous property and owned and operated as a single business by the same person(s), at the time a confirmed release is discovered. A facility does not include petroleum storage tanks used in different businesses, or owned by different persons, and connected through permanent or temporary piping used to transfer petroleum products from one business to another at the time a confirmed release was discovered.
(4) "Petroleum storage tank" has the meaning provided in 75-11-302, MCA.
(5) The department may rescind a release number if the department determines that the release should not have been confirmed. This determination must be based on substantial evidence upon which the department may conclude that the release did not occur, that the contamination did not exceed standards cited in ARM 17.56.506, or that the contamination does not meet the criteria set forth in (2) and should have been attributed to an earlier confirmed release that has been assigned a release number.