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Record of Decision System (RODS)



Address:  3 MI SE OF ANACONDA 
City & State:  ANACONDA  MT  59711
EPA ID:  MTD093291656
EPA Region:  08
NPL Status:  Currently on the Final NPL
ROD Type:  Record of Decision
ROD ID:  EPA/541/R-98/096
ROD Date:  09/29/1998
Operable Unit(s):  04
Media:  Groundwater, Sediment, Soil, Solid Waste, Surface Water
Contaminant:  Inorganics, Metals, Radioactive
Abstract:  Please note that the text in this document summarizes the Record of Decision for the purposes of facilitating searching and retrieving key text on the ROD. It is not the officially approved abstract drafted by the EPA Regional offices. Once EPA Headquarters receives the official abstract, this text will be replaced.

The Anaconda Smelter site is located in the Deer Lodge Valley in southwestern Montana, in and around the city of Anaconda about 25 miles northwest of the city of Butte. Milling and smelting activities conducted at the Old Works and Washoe Reduction Works smelters for nearly 100 years resulted in the contamination of various environmental media in the surrounding area, primarily through airborne emissions and disposal practices from smelting operations. The site is zoned industrial and includes residential and commercial properties.

Around 1884, the Anaconda Mining Company (AMC) and its predecessors commenced large copper concentrating and smelting operations at the area presently known as the Old Works. In about 1902 ore processing and smelting operations began at the Washoe Reductions Works. In 1977, Atlantic Richfield Company (ARCO) purchased AMC and expressly assumed its liabilities. Operations at the Anaconda Smelter ceased in 1980, and the smelter facilities were dismantled soon thereafter. The only substantial feature remaining from the smelter facility is the large brick smelter stack on Smelter Hill. ARCO has been identified as the potentially responsible party for this site.

The Anaconda Smelter site was placed on the National Priorities List (NPL) in September 1983. The U.S. Environmental Protection Agency (EPA) issued both general and special notice letters to ARCO on several occasions, and ARCO has been actively involved in conducting investigations and response actions at the site since that time. In April 1984, ARCO entered into an Administrative Order on Consent (AOC) with EPA to conduct demolition activities at the smelter. In October 1984, ARCO entered into another AOC to conduct several investigations at the Anaconda Smelter site to characterize soils, surface water, groundwater, and solid wastes. Early draft reports based on initial investigations indicated widespread contamination and the need for more in-depth study. In 1988, EPA, the State and ARCO entered into a series of orders and agreements. The primary document became the AOC-88-16, which initiated several remedial investigations/feasibility (RI/FS) studies on various operable units (OUs) throughout the site.

The Anaconda Regional Water, Waste, and Soils (ARWWS) OU combines the former ARWW, Anaconda soils, and Smelter Hill OUs. This OU is intended to be the last comprehensive OU at the site by addressing all remaining issues not addressed by previous actions. The OU addresses potential impacts to surface and ground water from soils and waste sources such as tailings and slag.
In 1992, EPA approved the final work plan for the ARWW Screening Study, and ARCO commenced a three-year groundwater and surface water sampling and waste characterization program. The ARWW RI/FS was formally started with an amendment to AOC-88-16 in September 1994. ARCO used results of the screening study to complete the RI analysis. EPA approved the final RI in March 1996, and the FS in 1997. A Record of Decision (ROD) was signed September 1998, providing several remedies for the waste media types found throughout the OU.

OU7 is the Old Works/East Anaconda Development Area (OW/EADA), which was used for mining and refining operations from 1884 to 1980. This OU contains large quantities of milling and smelting wastes, soils contaminated by smelter emissions, and other debris associated with the milling operation. Approximately 1.4 million cubic yards of tailings, slag, sands, and other wastes remain on site. Most wastes within the site have remained undisturbed since the turn of the century. Current industrial uses within the OW/EADA OU are a mixture of industrial and recreational.

In September 1988, EPA entered into an AOC with ARCO to conduct an Engineering Evaluation/Cost Analysis (EE/CA) for the Old Works OU. The final EE/CA Report addressing these areas was approved by EPA in July 1991. In 1992, EPA and ARCO amended the AOC to conduct OW/EADA OU investigations. The OW/EADA RI/FS, initiated in 1992, was completed in September 1993. A ROD for the OW/EADA OU was completed in March 1994, providing a combination of engineering and institutional controls as the remedy.

In September 1988, EPA entered into an AOC with ARCO to conduct an RI/FS for the Flue Dust OU. A ROD was completed in September 1991, providing for the treatment and disposal of all flue dust located on Smelter Hill.

The Mill Creek OU is approximately 140 acres and contains soils contaminated with arsenic as a result of smelter emissions. In October 1984, ARCO entered into an AOC to conduct a RI at the site. The initial stages of the investigations discovered that the soils within the community of Mill Creek, located 2 miles east of Anaconda, had elevated levels of arsenic. Children in Mill Creek also had elevated urinary arsenic levels. Families with young children were temporarily relocated from their community in May 1986. At that time, flue dust was sprayed with surfactant to reduce fugitive emissions, and contaminated road dust in the community was treated to reduce inhalation exposures. Following the temporary relocation, none of the children maintained levels of urinary arsenic above the levels of concern as determined by the Center for Disease Control. In July 1986, EPA entered into an AOC with ARCO to conduct an expedited RI/FS for Mill Creek. ARCO completed the RI/FS in September 1987. The ROD for Mill Creek was completed in October 1987. The selected remedy involved the permanent relocation of residents, which was completed in fall 1988. Volume VI (Mill Creek addendum) of the OW/EADA RI/FS summarized sample results from data collected from the Mill Creek OU in 1993. A ROD was completed in July 1994, for the OW/EADA OU, which included a final remedy for the Mill Creek OU.

The Community Soils OU addresses all residential and commercial/industrial soils throughout the Anaconda Smelter NPL site. It includes the communities of Anaconda, Opportunity, Fairmont, Galen, and Warm Springs. The majority of this land is classified as rural. The five communities included in the study area have a combined population of under 8,600. Prior to closure of smelter operations in 1980, the Anaconda Smelter was a source of substantial air emissions in the state. Other sources of aerial contaminants related to the Anaconda milling and smelting operations have also contributed to community soil contamination.

In September 1988, ARCO entered into an AOC with EPA to conduct an EE/CA study and investigation for the Community Soils OU. Results of sampling conducted by ARCO in 1988-1989 in the neighborhoods of Teresa Ann Terrace, Elkhorn Apartments, and Cedar Park Homes indicated the presence of elevated heavy metal concentrations at or near the soil surface. Sampling conducted by ARCO in 1990 confirmed the presence of elevated concentrations of heavy metals in several yards, gardens, and common areas of the three neighborhoods. A September 1991, Action Memorandum (with a concurrent AOC) required ARCO to conduct a Time-Critical Removal Action by excavating and removing contaminated soils in areas of Teresa Ann Terrace, Elkhorn Apartments, and Cedar Park Homes where arsenic concentrations exceeded 250 milligrams per kilogram.

In 1991, ARCO and EPA amended an AOC to conduct the Anaconda Soils Investigation to provide information to support future RI/FS activities at the Anaconda Smelter NPL Site. In 1992, ARCO initiated an Arsenic Exposure Study. Data from this study were utilized by the EPA in the Final Baseline Human Health Risk Assessment (HHRA) for the Anaconda Smelter Site. The Community Soils OU RI/FS was completed in 1996, and EPA signed a ROD in September 1996.
Remedy:  The selected remedy for the Anaconda Regional Water, Waste, & Soils Operable Unit (ARWW&S OU) is comprised of several remedies for the waste media types found throughout the OU. The major components of these remedies are described below.

Major components of the remedy for contaminated soils and waste material include: 1) reduction of surficial arsenic concentrations to below the designated action levels of 250 parts per million (ppm), 500 ppm, and 1,000 ppm through a combination of soil cover or in situ treatment; 2) reclamation of the soils and waste area contamination by establishing vegetation capable of minimizing transport of contaminants of concern (COCs) to groundwater and windborne and surface water erosion of the contaminated soils and waste areas. This vegetation will also provide habitat consistent with surrounding and designated land uses; and 3) partial removal of waste materials followed by soil cover and revegetation for areas adjacent to streams. Removed material will be placed within designated waste management areas (WMAs).

Major components of the remedy for groundwater include: 1) for alluvial aquifers underlying portions of the Old Works and South Opportunity Subareas, cleanup to applicable State of Montana water quality standards through use of soil covers, natural attenuation, and removal of sources (surface water) of groundwater contamination; and 2) for the bedrock aquifers and a portion of the alluvial aquifer in the Old Works/Stucky Ridge and Smelter Hill Subareas, waiver of the applicable groundwater standard. The aquifers underlying these subareas cannot be cost effectively cleaned up through reclamation, soil cover, or removal of the sources (wastes, soils, and tailings) of the groundwater contamination. Reclamation of soils and waste source areas with revegetation is required, which will contribute to minimizing arsenic and cadmium movement into the aquifers; and 3) for portions of the valley alluvial aquifers underneath theOld Works/Stucky Ridge, Smelter Hill, and Opportunity Ponds Subareas where groundwater is underlying waste-left-in-place, point of compliance (POC) monitoring to ensure contamination is contained at the perimeter boundary of the designated waste management area (WMA). Should POC monitoring show a spread of contaminants beyond the boundary of a WMA, treatment options will be instituted for the groundwater where practicable.

Major components of the remedy for surface water include: 1) reclamation of contaminated soils and engineered storm water management options to control overland runoff into surface waters; and 2) selective source removal and stream bank stabilization to minimize transport of COCs from fluvially deposited tailings into surface waters. Removed material will be placed within a designated WMA.

The remedy will employ Institutional Controls (ICs) and Operations and Maintenance (O&M) to ensure monitoring and repair of implemented actions. The remedy calls for a fully-funded ICs program at the local government level. The Anaconda-Deer Lodge County (ADLC) government will be responsible for on-going oversight of O&M in the Old Works/East Anaconda Development Area (OW/EADA) OU, implementation of a county-wide Development Permit system (DPS), and provision of public information and outreach through a Community Protective Measures program. In addition, the remedy will bring closure to previous response actions within the site that are already implemented, such as the Flue dust remedy or the Old Works remedy, primarily through long term O&M for some or all of those actions that are integrated into this remedy.

The ARWW&S OU encompasses a very large area, with remedial action slated for approximately 20,000 acres. The size of the OU and the focus on land reclamation as the key remedy will require management tools during Remedial Design/Remedial Action (RD/RA) activities to help direct, prioritize, and sequence response actions and allow for changing community interests. Management of the OU can be accomplished with the following elements: 1) a site management plan (SMP) will provide a framework for future RD/RA activities and will incorporate remedial unit designations and sequencing criteria for the RD/RA actions; 2) final implementation of the Regional Historic Preservation Programmatic Agreement will be accomplished. Separate agreements to address tribal cultural resources will be included; and 3) assessment and mitigation of impacts to wetlands from implementation of the remedy and communications with U.S. Fish and Wildlife Service will be coordinated.

Estimated Capital Costs: Not Documented
Estimated Annual O&M Costs: Not Documented
Estimated Present Worth Costs : $162,555,000
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