Site Name: MONTANA POLE AND TREATING
EPA ID: MTD006230635 EPA Region: 08 Metro Statistical Area:
202 W GREENWOOD, BUTTE, MT 59701
Operable Unit: 01
ROD ID: EPA/ROD/R08-93/075 ROD Date: 09/21/93
Contaminant: Organics, Metals
Keys: Arsenic; Biodegradation/Land Application; Carbon Adsorption (GAC); Carcinogenic Compounds; Chromium; Contingent Remedy; Debris; Decontamination; Dioxin; Direct Contact; Excavation; Filling; Floodplain; Ground Water; Ground Water Monitoring; Ground Water Treatment; Incineration/Thermal Destruction; Institutional Controls; Lead; MCLGs; MCLs; Metals; O&M; Offsite Disposal; Offsite Treatment; Oils; Onsite Containment; Onsite Discharge; Onsite Disposal; Onsite Treatment; Organics; PAHs; Phenols; Plume Management; Safe Drinking Water Act; Sediment; Sludge; Soil; Soil Washing/Flushing; State Standards/Regulations; Surface Water; Surface Water Monitoring; Treatment Technology
Abstract:
The Montana Pole and Treating site is a former wood treating facility located in Butte, Montana. Land use in the area is predominantly industrial, with some commercial and residential areas adjacent to the site. The site borders Silver Bow Creek, a former smelter site, and the Butte/Silver Bow Creek Superfund site, and lies within the 100-year floodplain of Silver Bow Creek. Residents near the site use one ground water well for domestic purposes and lawn watering. From 1946 to 1984, onsite wood treating operations utilized a five percent PCP solution mixed with petroleum carrier oil to preserve the timber, except for a brief period in 1969 when creosote was used as a wood preservative. This solution was applied to wood products in butt vats and pressure cylinders (retorts), and the retorts were used to dry timber by the Boulton process, which produced a residual two-phase oil and water condensate. The water phase reportedly was discharged into an onsite, unlined drainage ditch, which flowed toward Silver Bow Creek. In addition, onsite sedimentation ponds in the wastewater discharge ditch area apparently were used for the disposal of waste generated by the wood treatment process. In 1969, an onsite fire destroyed several of the plant areas, which were later rebuilt. But as a result of this fire, an onsite spillage of the PCP/petroleum product occurred. Additional seepage of the product resulted from broken pipes and valves damaged by the fire. In 1980, a closed-loop process water system was constructed to eliminate overland discharges of Boultonizing water. In 1983, a citizen complaint concerning oil seeping into Silver Bow Creek prompted a State investigation that verified an oil seep and detected oil-saturated soil onsite and adjacent to the creek. In 1985, an EPA and State investigation confirmed the presence of PCP, PAHs, and dioxins/furans in onsite soil and oil samples. Subsequently, in 1985, EPA initiated a removal action which included excavation and onsite temporary storage of approximately 10,000 yd[3] of contaminated soil; dismantling and temporarily storing onsite tanks, retorts, pipes, and other hardware; installation of two ground water interception/oil recovery systems to alleviate oil seepage into the creek; and fencing. In 1992, EPA initiated a second removal action to control and recover floating LNAPLs from the ground water. This process included the installation of a 890-foot sheet piling and ten recovery wells, each one containing two pumps: one to collect free-floating oil and pump it to an onsite storage tank and the other to pump contaminated ground water to an onsite granular activated carbon treatment facility. In 1993, the water treatment facility began operations and the system installed in 1985 was shut down. This ROD provides a final remedy for onsite contamination of the hot spot areas, former plant process area, the drainage ditch running to Silver Bow Creek, wastewater discharge ditch area, and the LNAPL plume. The primary contaminants of concern affecting the soil, sediment, debris, sludge, ground water, and surface water are organics, including dioxin, oils, PAHs, and phenols; and metals, including arsenic, chromium, and lead. SELECTED REMEDIAL ACTION: The selected remedial action for this site includes excavating approximately 208,000 yd[3] of contaminated soil to a depth of two to four feet from the surface soil hot spots, the former process area, the wastewater discharge ditch, and soil areas near the ground water table that are impacted by LNAPLs; treating onsite the excavated soil and approximately 10,000 yd[3] of contaminated soil, stored onsite since the 1985 removal action, using above-ground bioremediation; treating approximately 44,000 yd[3] of inaccessible contaminated soil by extracting LNAPLs, followed by soil flushing and in-situ bioremediation; backfilling the excavated areas with the treated soil, installing soil covers, and regrading and revegetating the area; incinerating offsite approximately 26,500 gallons of contaminated sludge, LNAPLs, and oil, with offsite disposal of residuals; decontaminating approximately 9,100 yd[3] of debris and equipment onsite, with offsite disposal in a RCRA landfill; containing contaminated ground water and LNAPLs using physical and/or hydraulic barriers to prevent the spread of contamination and to limit releases of contamination to Silver Bow Creek; treating contaminated ground water onsite using oil/water separation and granular activated carbon, and bioremediation or UV oxidation, if necessary, followed by onsite discharge of the treated water to surface water or reinjection into the aquifer; treating inaccessible ground water by in-situ bioremediation; allowing surface water to naturally attenuate; addressing contaminated stream sediment through natural biodegradation; monitoring ground water; and implementing institutional controls, including deed and ground water use restrictions. The estimated present worth cost for this remedial action ranges from $27,530,000 to $55,200,000, which includes an estimated annual O&M cost ranging from $657,000 to $4,420,000. PERFORMANCE STANDARDS OR GOALS: Chemical-specific soil, sediment, sludge, and debris cleanup goals are based on a health risk of 10[-6], and include benzo(a)anthracene 4,200 ug/kg; benzo(a)pyrene 4,200 ug/kg; benzo(b)fluoranthene 4,200 ug/kg; dioxins/furans 0.2 ug/kg; indeno(1,2,3-cd)pyrene 4,200 ug/kg; and PCP 34,000 ug/kg. Chemical-specific ground water cleanup goals are based on SDWA MCLGs and MCLs or risk-based levels, and include acenaphthene 360 ug/l; anthracene 360 ug/l; benzo(a)anthracene 1 ug/l; benzo(b)fluoranthene 0.2 ug/l; benzo(g,h,i)perylene 1 ug/l; benzo(k)fluoranthene 1 ug/l; benzo(a)pyrene 0.2 ug/l; 2-chlorophenol 45 ug/l; chrysene 1 ug/l; dibenzo(a,h)anthracene 0.2 ug/l; 2,4-dichlorophenol 27 ug/l; dioxins/furans 3x10[-5]; flouranthene 360 ug/l; fluorene 360 ug/l; indeno(1,2,3-cd)pyrene 1 ug/l; PCP 1 ug/l; phenanthrene 360 ug/l; pyrene 360 ug/l; 2,3,5,6-tetrachlorophenol 267 ug/l; and 2,4,6-trichlorophenol 6.5 ug/l. Chemical-specific surface water cleanup goals are based on SDWA MCLGs and MCLs and State standards, and include benzo(a)anthracene 1 ug/l; benzo(a)pyrene 0.2 ug/l; benzo(b)fluoranthene 0.2 ug/l; chrysene 1 ug/l; dibenzo(a,h)anthracene 0.2 ug/l; PCP 1 ug/l; and pyrene 360 ug/l. INSTITUTIONAL CONTROLS: Deed and ground water use restrictions will be implemented to prevent access to or impacts upon contaminated onsite ground water and to protect the integrity of the soil covers.
Remedy:
This is the final action for the only operable unit for the Site. The operable unit includes all known sources and contaminated media at the Site. This action addresses the principal threats remaining and provides for treatment of contaminated soils and groundwater. Some treatment residuals and soils contaminated at lower levels will remain on-site, such that the Site will require long-term management.
The principle contaminants of concern at the Site are pentachlorophenol (PCP), polynuclear aromatic hydrocarbons (PAHs), polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans. This Record of Decision establishes cleanup levels for these and all other contaminants of concern at the Site. The major components of the selected remedy include:
1. Excavation of contaminated soils from accessible areas of the site, to the extent practicable. The volume of soils is estimated to be approximately 208,000 cubic yards;
2. Treatment of excavated soils (208,000 cubic yards approximately) and previously removed soils (10,000 cubic yards approximately) by above ground biological treatment;
3. In-place biological treatment of contaminated soils below the depth of excavation before backfilling;
4. Backfill of excavated and treated soils into excavated areas if possible, surface grading and revegetation:
5. Soil flushing of inaccessible soils areas (principally underlying Interstate 15/90) in order to recover hazardous substances;
6. Containment of contaminated groundwater and LNAPL using physical and/or hydraulic barriers (as determined during remedial design) in order to prevent the spread of contaminated groundwater and LNAPL and to limit releases of contamination into SilverBow Creek;
7. Treatment of extracted groundwater using the present EPA water treatment plant (which consists of oil/water separation followed by granulated activated carbon treatment). The ultimate design of the groundwater treatment system (as determined during remedial design) may include the addition of biological means or ultraviolet oxidation (UV/oxidation) to maximize cost effectiveness of the treatment system. Treatment will meet standards for discharge or reinjection, as appropriate;
8. Discharge of extracted, treated groundwater into Silver Bow Creek and/or reinjection of extracted, treated groundwater into the aquifer (as determined during remedial design);
9. Enhanced in-situ biological treatment of contaminated groundwater, inaccessible contaminated soils areas and contaminated soils not recovered by excavation;
10. Treatment of contaminated site debris and equipment by decontamination followed by disposal of these materials in a licensed off-site landfill;
11. Treatment of contaminated oils and sludges in a licensed off-site incinerator;
12. Additional institutional controls preventing access to contaminated soils and groundwater; and
13. Groundwater monitoring to determine movement of contaminants and compliance with remedial action requirements.
Both soils and groundwater will be remediated at the Site. Soils will be excavated from four general areas: surface soil hot spot areas, surface and subsurface soils in the former plant process area, surface and subsurface soils along the historic drainage ditch running from the former plant process area to Silver Bow Creek and subsurface soils near the groundwater table which have been contaminated by floating wood treating product. The selected treatment technology for contaminated soils is above ground biological treatment. Some contaminated soils and associated wood treating fluid will remain in place due to inaccessibility and limits of excavation technology. These contaminated soils will be treated in place by in situ biological degradation.
Contaminated groundwater and any residual wood treating fluids left after excavation, will be contained from further migration using hydraulic and/or physical barriers. To create hydraulic containment of contaminated groundwater, some contaminated water will be extracted, treated and discharged to Silver Bow Creek. Other extracted and treated water will be reinfiltrated on-site to assist in hydraulic containment, flushing of contaminated areas and in situ biological degradation. Extracted groundwater will be treated above ground in the water treatment plant constructed at the site by EPA. This facility presently consists of oil/water separation and granulated activated carbon treatment. The ultimate design of the groundwater treatment system may include the addition of biological means or ultraviolet oxidation (UV/oxidation) to maximize cost effectiveness of the treatment system.