(1) The department shall rank each listed facility that is determined by the department to require remedial action and the ranking decision will be made in writing.

(2) A maximum priority designation must be given to a facility that exhibits one or more of the following characteristics:

(a) documented release to surface water in a drinking water intake that is a public drinking water supply with:

(i) a documented or probable exceedance of a Montana water quality human health standard listed in department Circular DEQ-7, entitled "Montana Numeric Water Quality Standards," or a standard established as a drinking water maximum contaminant level listed at 40 CFR 141; or

(ii) for substances whose parameters for human health are not listed in DEQ-7 or 40 CFR 141, concentrations at levels that render the water harmful, detrimental, or injurious to a beneficial use;

(b) documented release to ground water in a drinking water well that is a public drinking water supply with:

(i) a documented or probable exceedance of a Montana water quality human health standard listed in department Circular DEQ-7, entitled "Montana Numeric Water Quality Standards," or a standard established as a drinking water maximum contaminant level listed at 40 CFR 141; or

(ii) for substances whose parameters for human health are not listed in DEQ-7 or 40 CFR 141, concentrations at levels that render the water harmful, detrimental, or injurious to a beneficial use;

(c) documented release into a drinking water line that is part of a public drinking water supply with:

(i) a documented or probable exceedance of a Montana water quality human health standard listed in department Circular DEQ-7, entitled "Montana Numeric Water Quality Standards," or a standard established as a drinking water maximum contaminant level listed at 40 CFR 141; or

(ii) for substances whose parameters for human health are not listed in DEQ-7 or 40 CFR 141, concentrations at levels that render the water harmful, detrimental, or injurious to a beneficial use;

(d) documented release to surface water in a drinking water intake that is a domestic or commercial drinking water supply with:

(i) a documented or probable exceedance of a Montana water quality human health standard listed in department Circular DEQ-7, entitled "Montana Numeric Water Quality Standards," or a standard established as a drinking water maximum contaminant level listed at 40 CFR 141; or

(ii) for substances whose parameters for human health are not listed in DEQ-7 or 40 CFR 141, concentrations at levels that render the water harmful, detrimental, or injurious to a beneficial use;

(e) documented release to ground water in a drinking water well that is a domestic or commercial drinking water supply with:

(i) a documented or probable exceedance of a Montana water quality human health standard listed in department Circular DEQ-7, entitled "Montana Numeric Water Quality Standards," or a standard established as a drinking water maximum contaminant level listed at 40 CFR 141; or

(ii) for substances whose parameters for human health are not listed in DEQ-7 or 40 CFR 141, concentrations at levels that render the water harmful, detrimental, or injurious to a beneficial use;

(f) documented release into a drinking water line that is a domestic or commercial drinking water supply with:

(i) a documented or probable exceedance of a Montana water quality human health standard listed in department Circular DEQ-7, entitled "Montana Numeric Water Quality Standards," or a standard established as a drinking water maximum contaminant level listed at 40 CFR 141; or

(ii) for substances whose parameters for human health are not listed in DEQ-7 or 40 CFR 141, concentrations at levels that render the water harmful, detrimental, or injurious to a beneficial use;

(g) presence of explosive vapor levels or concentrations of vapors that could cause acute health effects in a structure or utility corridor;

(h) indications of an imminent danger of fire or explosion or a release of dangerous levels of vapors in ambient air; or

(i) presence of free product in significant quantities in the ground water, in or on surface water bodies, in utilities other than water supply lines, or in surface water runoff.

(3) A high priority designation must be given to a facility whose release does not exhibit any of the characteristics provided in (2) but exhibits one or more of the following characteristics:

(a) documented release to surface water that is a drinking water source with:

(i) no documented or probable exceedance of a Montana water quality human health standard listed in department Circular DEQ-7, entitled "Montana Numeric Water Quality Standards," or a standard established as a drinking water maximum contaminant level listed at 40 CFR 141 in a drinking water supply intake; and

(ii) for substances whose parameters for human health are not listed in DEQ-7 or 40 CFR 141, no concentration at levels that render the water harmful, detrimental, or injurious to a beneficial use in a drinking water supply intake;

(b) documented release to ground water that is a drinking water source with:

(i) no documented or probable exceedance of a Montana water quality human health standard listed in department Circular DEQ-7, entitled "Montana Numeric Water Quality Standards," or a standard established as drinking water maximum contaminant level listed at 40 CFR 141 in a drinking water supply well; and

(ii) for substances whose parameters for human health are not listed in DEQ-7 or 40 CFR 141, no concentrations at levels that render the water harmful, detrimental, or injurious to a beneficial use in a drinking water supply well;

(c) documented release to ambient air that poses a threat to public health;

(d) documented release of a hazardous or deleterious substance on the ground surface that poses a threat to public health;

(e) migration of contamination to a utility corridor currently in use;

(f) threat of explosive vapor levels or concentrations of vapors that could cause health effects by accumulating in a structure or utility corridor;

(g) documented and extensive contamination of exposed shallow soil or exposed sediment with uncontrolled facility access;

(h) documented existence of a hazardous or deleterious substance in a container or impoundment that is leaking or that presents an imminent threat of leakage in an area with uncontrolled facility access;

(i) documented impact to a sensitive environment.

(4) A medium priority designation must be given to a facility that does not exhibit any of the characteristics provided for in (2) or (3) but exhibits one or more of the following characteristics:

(a) documented or probable release to surface water that is not a drinking water source but is used for a beneficial use;

(b) documented or probable release to ground water that is not a drinking water source but is used for a beneficial use;

(c) documented or probable release into a water line that is not used as a drinking water source but is used for a beneficial use;

(d) imminent threat from migration of contamination from soil to:

(i) surface water that is a drinking water source;

(ii) ground water that is a drinking water source; or

(iii) a water line that is a drinking water source;

(e) potential release to air that may pose a threat to public health;

(f) potential for migration of contamination to a utility corridor currently in use;

(g) documented contamination to a utility corridor not in use;

(h) documented or probable localized contamination of soil;

(i) presence of containers or impoundments containing hazardous or deleterious substances that are leaking or that present an imminent threat of leakage in an area with controlled facility access;

(j) documented or probable extensive contamination of soil with controlled facility access; or

(k) potential impact to a sensitive environment.

(5) A low priority designation must be given to a facility that does not exhibit any of the characteristics provided for in (2), (3), or (4) but which does require remedial action. A low priority facility exhibits one or more of the following characteristics:

(a) minimal potential for release to surface water that is not used for any purpose other than primary contact activities;

(b) minimal potential for release to ground water that is not used for any purpose other than primary contact activities;

(c) minimal potential for release into a water line that is not used for any purpose other than primary contact activities;

(d) minimal potential for release to air that may pose a threat to public health;

(e) minimal potential for release to a utility corridor; or

(f) minimal documented release or potential for release to soil with minimal potential for direct contact hazard.

(6) An operation and maintenance designation must be given to a facility on the CECRA priority list at which remedial actions are complete but which is undergoing operation and maintenance, including but not limited to revegetation monitoring, surface water monitoring, ground water monitoring, or waste repository maintenance. Facilities with an operation and maintenance designation will be maintained on the CECRA priority list in a separate category.

(7) The department may reevaluate the rank of a facility if the department obtains or receives additional information that may cause a change in rank. Compliance with ARM 17.55.108 is not required to change the rank of the facility.

(8) Any person may submit a request to the department to evaluate a facility on the priority list for purposes of changing the rank of the facility. The request must be in writing and contain the rationale for the reclassification. The department may determine such a change in rank is appropriate. Compliance with ARM 17.55.108 is not required to change the rank of the facility.