Record of Decision

RReeccoorrdd ooff DDeecciissiioonn Missoula White Pine Sash Facility Missoula, Montana Prepared By: Montana Department of Environmental Quality Remediation Division Helena, Montana February 2015 Record of Decision Missoula White Pine Sash Facility Missoula, Montana Prepared by: Montana Department of Environmental Quality Remediation Division Helena, Montana February 2015 PART 1 DECLARATION OF RECORD OF DECISION Declaration of Record of Decision FACILITY NAME AND LOCATION The Missoula White Pine Sash (MWPS) Facility is a high priority state Superfund facility listed on the Montana Comprehensive Environmental Cleanup and Responsibility Act (CECRA) Priority List. The MWPS Facility is within the City of Missoula (City), Montana. STATEMENT OF PURPOSE AND BASIS This Record of Decision (ROD) is the document that presents the Montana Department of Environmental Quality’s (DEQ’s) selected remedial action for the MWPS Facility and was developed in accordance with CECRA. The remedial action selected in the ROD is based on the administrative record, which consists of the documents DEQ cited, relied upon, or considered in selecting the remedy for the MWPS Facility. The administrative record is identified in Part 2, Section 14.0 of the ROD. The complete administrative record is available for public review at the offices of DEQ, Remediation Division, located at 1225 Cedar Street in Helena, Montana. A partial compilation of the administrative record is available at the Main Branch of the Missoula Public Library, 301 E. Main St., Missoula; the University of Montana Mansfield Library; and on DEQ’s website at http://www.deq.mt.gov/StateSuperfund/missoulawhitepinesash.mcpx. ASSESSMENT OF THE FACILITY DEQ is authorized to take remedial action whenever there has been a release or a threatened release of a hazardous or deleterious substance into the environment that poses or may pose an imminent and substantial endangerment to the public health, safety, or welfare, or the environment. Section 75-10-711, MCA. CECRA defines a hazardous or deleterious substance in Section 75-10-701(8), MCA. The primary contaminants that DEQ identified at the MWPS Facility are pentachlorophenol (PCP), dioxins/furans (hereinafter referred to as “dioxin”), metals, methane, and petroleum hydrocarbons. These and other identified contaminants are described in Part 2 of the ROD. DEQ has determined that these contaminants are hazardous or deleterious substances under CECRA. Based on the administrative record, DEQ has determined that hazardous or deleterious substances have been spilled, leaked, discharged, leached, dumped, or disposed into the environment, which constitutes a release or threatened release under Section 75-10-701(19), MCA. The potential for an “imminent and substantial endangerment to public health, safety, and welfare, or the environment” is present when contaminant concentrations in the environment exist or have the potential to exist above risk-based screening levels (ARM 17.55.102) and an imminent and substantial endangerment does exist if contaminant concentrations exceed site- specific cleanup levels (SSCLs). DEQ has determined that contaminant concentrations at the MWPS Facility exceed risk-based screening levels and SSCLs. Therefore, DEQ has determined that a release or a threatened release of hazardous or deleterious substances from the MWPS Facility poses an imminent and substantial endangerment to the public health, safety, or welfare, or the environment and further remedial action is necessary. In selecting the remedial action, DEQ evaluated the criteria found in Section 75-10-721, MCA. Part 1 – Page 1 DESCRIPTION OF THE REMEDY Section 75-10-721(2)(c), MCA, directs DEQ to consider present and reasonably anticipated future uses of a facility when selecting remedial actions. The alternative selected must then meet SSCLs protective of the reasonably anticipated future uses. Section 75-10-701(18), MCA, defines “reasonably anticipated futures uses” as “likely future land or resource uses that take into consideration: (a) local land and resource use regulations, ordinances, restrictions, or covenants; (b) historical and anticipated uses of the facility; (c) patterns of development in the immediate area; and (d) relevant indications of anticipated land use from the owner of the facility and local planning officials.” DEQ’s evaluation of reasonably anticipated future uses of the MWPS Facility is found in Part 2, Section 6.0 of the ROD. In summary, DEQ determined that the reasonably anticipated future use of the WWW Investments, LLC (WWW) property, the City shop property, and the western portion of the Scott Street, LLP (SSLLP) property is commercial/industrial. DEQ also determined that the reasonably anticipated future use of the City park property is recreational, and that the reasonably anticipated future use of the eastern portion of the SSLLP property and the property east of Scott Street is residential. The remedy for the MWPS Facility consists of remediation of contaminated media to meet SSCLs as described in the ROD, with reliance on institutional controls. Numerous interim actions have occurred at the MWPS Facility. DEQ considered the interim remedial actions and integrated that information and those actions into the remedy to the extent possible. Major components of the remedy are summarized below. Details of the remedy are provided in Part 2, Section 11.0 of the ROD. Institutional Controls The selected remedy partially relies on the placement of DEQ-approved restrictive covenants on some of the properties that make up the MWPS Facility to limit the future use of portions of the WWW, City shop, and western portion of the SSLLP properties to commercial/industrial and to limit the use of the City park to recreational. (These restrictive covenants are not needed on the existing residential property east of Scott Street or on the eastern portion of the SSLLP property.) Groundwater use will be regulated in these restrictive covenants or a controlled groundwater area (or both) to prohibit installation of non-remediation wells at the Facility until SSCLs for groundwater are met. On the WWW property with subsurface soil contamination that will be treated over time, irrigation will be prohibited until SSCLs are met (or DEQ otherwise approves it) to ensure that the addition of irrigation water does not disrupt or otherwise change conditions during treatment. Use of a portion of the western portion of the SSLLP property will also be restricted for a short time to allow treatment of soils in a land treatment unit. These restrictive covenants will be in effect until DEQ determines they are no longer needed to ensure protection of public health, safety, or welfare or the environment. Part 1 – Page 2 Long-Term Groundwater and Soil-Vapor Monitoring The selected remedy includes long-term monitoring, which includes sampling of any, or all, of the existing monitoring well network that now includes approximately 54 wells or additional wells that may be installed or added as part of remedial design. Monitoring may also include some or all of the existing irrigation or public water supply wells. The monitoring wells and other wells that will be included in the long-term monitoring network will be determined after the ROD is issued, during or after remedial design. The groundwater monitoring of both the Missoula Aquifer and the perched groundwater will be used to monitor the effectiveness of the cleanup activities and to ensure SSCLs are met. Monitoring of natural attenuation for dioxin and metals in groundwater will also occur. In addition, long-term monitoring will include soil vapor monitoring from existing and any newly- installed monitoring points to confirm the effectiveness of the soil and groundwater remedies. Long-term monitoring is included in the site-wide elements. Soil The selected remedy includes a combination of excavation and offsite disposal, excavation and onsite enhanced ex-situ bioremediation, and in-situ chemical oxidation (ISCO), to treat the onsite residual sources of contaminants in soil at the MWPS Facility. These remedies will reduce contaminant concentrations in soil and soil vapor. The remedy includes excavation and off-site disposal at a licensed and permitted disposal facility of methane-containing surface and subsurface soil, ash/metals-contaminated subsurface soil, and dioxin-contaminated surface and subsurface soils that do not contain PCP. This soil may be disposed of at a local landfill (such as Allied Waste landfill). Methane-containing soil, which is primarily composed of wood waste, may also be recycled at a local composting company if it is determined through sampling not to contain contamination and is accepted by the composting company. Onsite enhanced ex-situ bioremediation of surface and subsurface soil includes the excavation and placement of PCP-impacted soil, which are classified as F032 listed hazardous waste, from the former treatment area into a land treatment unit located on the western portion of the SSLLP property within the Facility. DEQ will designate a Resource Conservation and Recovery Act corrective active management unit that will allow treatment of the PCP-impacted soil onsite. Bioremediation will significantly reduce the amount of contamination in soil. The selected remedy includes ISCO following excavation of surface and subsurface soils in the former treating area, and to address remaining subsurface soils contamination in the former above-ground storage tank area and beneath Scott Street. ISCO consists

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