35-11-1605. Voluntary remediation standards; site-specific, risk-based standards; considerations in choice of remedy; alternate standards for soil; alternate standards for soil or water; point of compliance; contamination from source not on site; alternate remediation standards for site contaminated from source not on site; supplemental requirements.

(a) Consistent with any requirements necessary to retain state primacy in federal programs, any remedy proposed by an owner of an eligible site, or considered by the director, shall:

(i) Be protective of human health, safety and the environment. A remedy shall be considered to be protective of human health if it reduces risk to human receptors of acute and chronic toxic exposures to contaminants to levels that do not pose a significant risk to human health. A remedy shall be considered to be protective of the environment if it adequately reduces risk of significant adverse impacts to ecological receptors for which habitats have been identified on or near the site. Remedies may meet this requirement through a combination of monitored natural attenuation, removal, treatment, or engineering or institutional controls. Except as provided in subsection (d) of this section, any site where a remedy is proposed that includes engineering or institutional controls must also have been designated as a use control area in accord with W.S. 35-11-1609;

(ii) Attain standards established by the director under this subsection for air, soil, and water affected by the site, unless the director sets an alternate standard in accord with subsection (c) or (d) of this section. No standard set under this section for a contaminant shall be set at a level or concentration lower than the background level or concentration for that contaminant. A remedy must attain standards or alternate standards by the end of the remediation period set forth in the remedy agreement. A remedy shall be considered to attain standards for air, soil and water if it:

(A) Meets any applicable media standards established under federal or state law or rule or regulation; or

(B) Meets site-specific, risk-based standards developed for the eligible site. Site-specific, risk-based standards shall establish a risk reduction goal for contaminants which are known or suspected carcinogens to ensure that the excess upper bound lifetime cancer risk to any exposed individual may not exceed a probability of developing cancer of one in one million (1 in 1,000,000) to one in ten thousand (1 in 10,000). The one in one million (1 in 1,000,000) risk level shall be used as the point of departure for determining remediation goals for alternatives when individual contaminant standards are not available, or are not sufficiently protective because of the presence of multiple contaminants at a site or multiple pathways of exposures. Site-specific, risk-based standards must also require that for contaminants which are systemic toxicants, the hazard index must not exceed one (1). The director shall use residential exposure factors, giving consideration to children and the elderly, to establish site-specific, risk-based standards under this subsection for soils and air. The exposure factors to be used by the director to establish site-specific, risk-based standards under this subsection for hazardous substances in groundwater shall assume that groundwater may be used as a drinking water source, provided that no standard set under this subsection for a contaminant shall be set at a level or concentration lower than the background level or concentration for that contaminant. For nonhazardous substances, the exposure factors to be used by the director shall assume uses consistent with the class of use prior to contamination of the groundwater.

(iii) Control any sources of releases so as to reduce or eliminate, to the extent technically practicable, further releases as required to protect human health and the environment. A remedy shall be considered to control sources of releases if it controls the release of contaminants from sources to any media in concentrations that exceed applicable standards set by the director under paragraph (a)(ii) of this section, or the soil standards under subsection (c) or (d) of this section; and

(iv) Comply with any applicable standard for management of wastes generated as a consequence of the remedy. A remedy shall be considered to comply with applicable standards for management of wastes if all wastes generated as a consequence of implementation of the remedy are treated, stored or disposed of in compliance with the requirements of this act.

(b) The director shall choose a remedy, or combination of remedies, from among those remedies which meet the requirements of subsection (a), (c) or (d) of this section, as applicable. In choosing a remedy, the director shall consider:

(i) The extent to which the remedy will be reliable and effective for the long term. For remedies that include engineering or institutional controls in accord with a use control area designation, the director shall consider the expected life cycle performance of any engineering controls, monitoring systems and institutional controls;

(ii) The extent to which the remedy results in a reduction of toxicity, mobility or volume of contaminants. The director shall consider the degree to which remedies incorporate treatment or removal of contaminants to lower long term risk to human health and the environment;

(iii) The short term effectiveness of the remedy. The director shall consider the time required for each remedy to attain standards for air, soil and water specified in paragraph (a)(ii) or subsection (c) or (d) of this section, as applicable. A remedy involving monitored natural attenuation may be considered whether or not the director has made a determination of technical impracticability under subsection (d) of this section. Monitored natural attenuation shall be deemed effective if there is evidence that natural attenuation is occurring and will be completed within a reasonable time period;

(iv) Impacts which may be caused by implementation of the remedy. The director shall consider any adverse impacts which may be caused by a remedy, and shall take into consideration the gravity of any projected impact and the cost and availability of measures to mitigate the impact;

(v) The extent and nature of contamination and practicable capabilities of remedial technologies, and whether achieving standards is technically impracticable;

(vi) Reasonably anticipated future land uses or use restrictions in a use control area designation;

(vii) Consistency of remedies with the nature and complexities of releases of contaminants; and

(viii) Cost of the remedy. The director shall consider whether a remedy presents a substantial and disproportionately high cost for implementation and completion. The director shall compare the costs of remedies considering the degree of risk reduction that is afforded by each remedy. Costs considered shall include capital, operation and maintenance, engineering and institutional control costs and monitoring costs for the anticipated life of the remedy.

(c) The director may establish alternate site-specific, risk-based standards for surface and subsurface soils to be employed at a site in lieu of the soil standards in paragraph (a)(ii) of this section, for any site that is located within a use control area designated under W.S. 35-11-1609. A remedy that employs alternate standards established by the director under this subsection shall meet the requirements of this subsection and paragraphs (a)(i), (iii) and (iv) of this section. The alternate standards for such a site shall use the carcinogenic and systemic toxicant risk reduction goals of subparagraph (a)(ii)(B) of this section, except that the exposure assumptions used to calculate the alternate standards under this subsection shall be consistent with the use restrictions contained in the use control area designation. If the director establishes alternate soil standards under this subsection, the owner or operator must evaluate technologies that can meet the alternate soil standards. Owners or operators of eligible sites that implement remedies which achieve the alternate soil standards set under this subsection may be issued a certificate of completion and covenant not to sue pursuant to W.S. 35-11-1607. The soil standards of paragraph (a)(ii) of this section must be met if the owner or operator applies to remove the use restrictions applicable to the site or to receive a no further action letter under W.S. 35-11-1608.

(d) The director may establish alternate site-specific, risk-based standards for soil or water to be employed at a site in lieu of the soil and water standards in paragraph (a)(ii) of this section if, after evaluation of currently available technology the director determines that it is technically impracticable to meet a standard at a specific site. A remedy that employs alternate standards established by the director under this subsection shall meet the requirements of this subsection and paragraphs (a)(i), (iii) and (iv) of this section. The technical impracticability determination shall include evaluation of the cost of remedy alternatives, including but not limited to, substantial and disproportionately high costs, present worth of construction, operation and maintenance costs, continued operational costs of the remedy selected and costs of any proposed alternative remedy strategies. Whenever the director sets an alternate standard, the director shall select a remedy capable of meeting the alternate standard and which is technically practicable, controls any sources of contamination to the extent technically practicable, and controls human and environmental exposures to contaminated air, soil or water. The director may establish alternate standards for soil or water under this subsection only if the owner has or obtains rights to control human or environmental exposures to contaminated media, and consents to impose such controls as are required to protect human health and the environment. Notwithstanding the provisions of paragraph (a)(i) of this section, or W.S. 35-11-1609 such controls may be imposed by the owner without the site receiving a use control area designation under W.S. 35-11-1609. The standards of paragraph (a)(ii) of this section must be met if the owner or operator applies to remove the use restrictions applicable to the site or to receive a no further action letter under W.S. 35-11-1608.

(e) When establishing standards under paragraph (a)(ii) or subsection (c) or (d) of this section, the director shall specify one (1) or more points of compliance where standards must be achieved. In specifying a point of compliance, the director shall consider the following factors:

(i) Compliance with groundwater standards shall be monitored as close as reasonably practical to the contaminant source or site boundary or boundary of the use control area. The director shall select any groundwater point of compliance based upon the evaluation of the properties of the aquifer, the proximity of existing and reasonably anticipated points of groundwater withdrawal or discharge to the surface, the location of the contaminant plume relative to the site or use control area boundary, the toxicity of the contaminant, the presence and proximity of multiple contaminant sources, the exposure and likelihood of actual exposure to contaminated groundwater, and the technical practicability of groundwater remediation;

(ii) For soils, standards shall be met at locations determined to ensure protection of human health and identified environmental receptors, and protection of surface water, groundwater and air resulting from any potential transfer of contaminants from soils to these other media; and

(iii) For surface water, standards shall be met at the point where any release enters any surface water of the state consistent with applicable federal and state requirements. If sediments are affected by releases to surface water, a sediment point of compliance may also be established.

(f) Remediation standards for a site that has become contaminated by a release or migration of contamination from a source not located on the site shall be appropriate for any use control area designation applicable to such site, or if desired by the owner the remediation requirements shall be adequate to restore the site to all uses for which it was suitable prior to the contamination.

(g) The department may establish supplemental requirements for owners or operators of lands or facilities subject to permitting or corrective action requirements of the hazardous waste rules and regulations promulgated under W.S. 35-11-503(d) as may be necessary to ensure that such sites are characterized and remediated in a manner which is consistent with, equivalent to, and no less stringent [than] permitting, closure, post-closure and corrective action requirements contained in rules and regulations adopted by the United States Environmental Protection Agency (EPA) under authority of subtitle C of the Resource Conservation and Recovery Act, 42 U.S.C. § 6901, et seq. Election by an eligible site owner or operator who is subject to such hazardous waste permitting or corrective action requirements to participate in the voluntary remediation program under this article shall not relieve the owner or operator of the duty to comply with all requirements of the hazardous waste rules and regulations promulgated under W.S. 35-11-503(d).