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REMEDIAL DESIGN AND CONSTRUCTION AT THE MONTANA POLE WOOD TREATING FACILITY

The MPTP site is a former wood treating facility located in Butte, Montana. Contamination of soils, ground water, and nearby Silver Bow Creek occurred from spillage and discharge of treating fluids used on site. The treating fluids consisted of pentachlorophenol (PCP) dissolved in diesel and as much as 500,000 gallons of "free product" is present on the water table.

For this project, CDM has provided a broad range of services to the MDEQ. These include remedial investigation (RI), feasibility study (FS), ground water modeling, human health and environmental risk assessment, remedial design, and remedial construction services. CDM completed the Phase 1 Remedial Design portion of the project, which required detailed coordination of numerous remedy components:

• Excavation of approximately 230,000 cubic yards of contaminated soils, followed by construction of above ground biological treatment units consisting of eighteen 2,000 cubic yard biopiles and a 10-acre biological land treatment unit

• Relocation of an active railroad track located above contaminated soils and ground water

• In situ enhancement of light non-aqueous phase liquid (LNAPL) recovery, and biological treatment of contaminated soils below the depth of excavation before backfilling, using a unique backhoe attached air injection system

• Soil flushing and air sparging of inaccessible soils areas (principally underlying Interstate 15/90) to recover LNAPLs and promote biological degradation

• Construction of two, 16,000 square-foot trenches utilizing biopolymer construction techniques to attain containment of contaminated ground water and LNAPLs

• Aboveground treatment of extracted ground water using oil/water separation, biological treatment, and activated carbon polishing

• Enhanced in situ bioremediation of contaminated ground water, inaccessible contaminated soils, and contaminated soils not recovered by excavation

• Treatment and disposal of contaminated site debris and equipment by decontamination, followed by disposal of these materials in a licensed, offsite landfill, and treatment of contaminated oils and sludges in a licensed, offsite incinerator.

Key words: remedial design, bioremediation, LNAPL