Montana Pole

  • Listed - July 1987
  • Administration Order on Consent for investigation – 1990
  • Record of Decision (ROD) for site-wide cleanup – 1993
  • Consent Decree for final cleanup – 1996
  • Construction Completion – 2001
  • 1st Five-Year Review – 2001
  • 2nd Five-Year Review – 2006

The Montana Pole and Treating Plant (MPTP) site is an abandoned 40-acre wood-treating facility in Butte, Montana. The Montana Pole and Treating Plant operated from 1946 until 1984 and is one of four Clark Fork Basin Superfund sites. Contamination consists of wood-treating products including pentachlorophenol and related chlorinated phenols, polynuclear aromatic hydrocarbons, dioxins/furans and petroleum compounds which spread into surrounding soils, groundwater and Silver Bow Creek.

In response to oil and wood-treating fluids seeping into Silver Box Creek, EPA conducted an emergency removal of contaminated soil beginning in 1985. EPA also installed a system to pump and treat contaminated groundwater to recover wood-treating chemicals and to prevent contamination from reaching Silver Bow Creek. Updated in 1992, this pump and treatment system will continue operating at least until the final remedy is implemented.

The Atlantic Richfield Company (ARCO) began a remedial investigation and feasibility study in 1990 under the direction of DEQ as lead agency. These activities were completed in 1993.

DEQ released the remedial investigation, feasibility study and proposed plan for public comment in spring 1993. EPA and DEQ issued the Record of Decision (ROD) for the Montana Pole Superfund Site in September 1993. The ROD requires the excavation and on-site biological treatment of approximately 200,000 cubic yards of site soils contaminated with pentachlorophenol (PCP), the construction and long-term operation of a groundwater interception and treatment system, and in situ treatment of contaminated soils and groundwater that are not accessible for excavation or by excavation of soils when the bridge is replaced by the Montana Department of Transportation (MDT). The cleanup is being conducted by DEQ, with assistance from EPA, under the terms of the MPTP Consent Decree entered by the U.S. District Court on July 16, 1996, and the EPA/DEQ MPTP Site-Specific Superfund memorandum of Agreement (SMOA).

The MPTP cleanup has been implemented in a number of phases. Beginning in 1996, Phase 1 consisted of the construction of the soil treatment facilities and modifications to the existing groundwater treatment plant, excavation and treatment of contaminated soils from the area on the site north of the Interstate highway, installation of the near-creek recovery trench to control groundwater at the northern boundary of the site, and installation of the near-highway recovery trench to prevent the recontamination of the excavated north-site area.

Phase 2, conducted in 1999, consisted of removal and disposal of the remaining MPTP structures and all site debris on the portion of the site south of the Interstate. Phase 2 was conducted to clear the south site area in preparation for the excavation and treatment of south site soils.

Phase 3 consisted of removal of treated soils from the land treatment unit (LTU) and backfill of the treated soils into the north site area; excavation of the south site soils and placement of the excavated soils onto the LTU; construction of in situ bioremediation treatment systems for groundwater in both the north and south site areas; and relocation of utilities to accommodate the south site excavation. Phase 3 construction began in September 1999 and was completed in December 2000.

Phase 4 is the treatment phase as soil and groundwater treatment continues. Phase 4 began in April 2001 with excavation of contaminated soils from around a sewer main that were inaccessible during Phase 1 and revegetation of the north site area. Phase 4 activities involving offloading a lift of soil from the LTU and other work were performed during October and November 2001. In May and June 2003, Phase 4 dust control measures were implemented. Treated soils from the eight SSPs were backfilled into the south side excavation area during September 2004. During July 2005, a lift of treated soils was removed from the LTU and placed in West Areas 1 and 2. Phase 4 also consists of revegetating the site as necessary. Additional Phase 4 activities will continue until all contaminated soils reach treatment standards and treated soils are backfilled on the site.

Phase 5 will address the contaminated soils and groundwater under the Interstate through in situ treatment. DEQ, MDT, EPA, and MBMG extensively evaluated the technical and economic feasibility of excavating and remediating the contaminated soils remaining beneath the Interstate 15/90 bridge embankment, and concluded in 2006 that it is not economically or technically reasonable to pursue excavation of these soils during MDT’s interstate bridge removal and replacement project. DEQ in consultation with EPA will evaluate in situ treatment options to address contamination remaining beneath the Interstate and implement these options as appropriate.

Phase 6 will consist of the removal and demolition of the soil treatment facilities, which are located in the south site area. After the soil treatment facilities are removed, the south site area will be graded and revegetated or surfaced consistent with potential long-term use of the property by Butte-Silver Bow County. DEQ will continue to operate the water treatment plant and in situ treatment facilities. Groundwater cleanup is expected to last 30 years.