Montana Pole and Treating operated as a wood-treating plant from 1946 to 1984 on the western edge of Butte, Montana. The facility used pentachlorophenol (PCP) mixed with oil to preserve wood, and briefly used creosote in 1969. Hazardous substances from those operations reached a nearby ditch that flowed toward Silver Bow Creek, contaminating soil, sediment, surface water, and groundwater. The site was added to EPA's National Priorities List (NPL) in 1987 and remains listed today.
More than 60 contaminants of concern have been identified at the site. These include metals such as arsenic, lead, copper, chromium, manganese, and zinc. Chlorinated dioxins and furans are found in soil, sediment, groundwater, and surface water. Polycyclic aromatic hydrocarbons (PAHs) such as benzo(a)pyrene and pyrene are present, along with chlorinated phenols including pentachlorophenol and 2,4,6-trichlorophenol. Many of these contaminants appear across multiple media.
Cleanup began in 1985 with excavation of heavily contaminated soils. The long-term remedy was selected in 1993 and built between 1996 and 2001. It included a Land Treatment Unit (LTU) to treat contaminated soils, groundwater recovery trenches, and a water treatment plant. Treated soils were placed in a capped on-site containment area called a Corrective Action Management Unit (CAMU). The site reached cleanup levels for PCP and PAHs, but not for dioxin. An Explanation of Significant Differences issued in March 2021 modified the remedy, adjusting cleanup standards and institutional controls. The most recent five-year review took place in September 2022, and the next is estimated between September and November 2027.
EPA assessment shows that human exposure is currently under control across the entire site, with no unacceptable pathways for people to contact contamination. Contaminated groundwater has been stabilized and is not discharging to surface water at unacceptable levels, though monitoring will continue for at least 30 years. About 27 acres of the site are available for commercial and industrial redevelopment. The remaining 9 acres make up the CAMU and will stay in place. Permanent institutional controls are being developed to restrict residential use on the whole fenced property.
Community members who want to stay involved can contact the Citizens Technical Environmental Committee (CTEC), a Technical Assistance Grant group based in Butte. CTEC can be reached at (406) 723-6247 or ButteCTEC@hotmail.com, or by mail at 27 West Park Street, P.O. Box 0593, Butte, MT 59703-0593. Public records related to the site are available at the Montana Tech Library at 1300 West Park Street in Butte. The EPA Remedial Project Manager and State Project Officer are also available to answer questions directly.
