Soil & Groundwater | Region 10 | US EPA

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Soil & Groundwater

The Soil Operable Unit includes former Wyckoff operating areas including the Former Log Storage/Peeler Area, the Former Process Area, and the Well CW01 Area (see Figure). There is widespread near-surface and subsurface soil contamination in these areas, with very elevated levels of contamination in the Former Process Area. The contaminants of concern (COCs) in soil are PAHs, pentachlorophenol, and dioxins/furans.

The Groundwater Operable Unit includes the soil and groundwater in the saturated zone beneath the Soil Operable Unit (see Figure). The Groundwater OU is composed of two water-bearing zones separated by a layer of low-permeability material, called the aquitard. Non-aqueous phase liquid (NAPL) “pools” have been located in the upper aquifer beneath the Former Process Area. An interim ROD was issued in September 1994 for the Groundwater OU which focused on the actions necessary to contain contaminated groundwater to the Wyckoff site, i.e., replace the existing treatment plant, maintain and upgrade the extraction system, install a physical barrier, and seal on-site drinking water wells that could act as conduits for migration of contaminants to deeper aquifers.

In February 2000, EPA issued a final ROD for the Soil and Groundwater OUs conditionally selecting thermal remediation (i.e., steam injection) as the cleanup remedy. This remedy included constructing a sheet pile wall around the highly contaminated Former Process Area, conducting a pilot study to test the effectiveness of steam injection, consolidating contaminated soil from outside to within the Former Process Area, monitoring the lower aquifer groundwater, and implementing institutional controls. If the steam injection pilot study does not meet performance goals, then the contingency of site containment will be implemented. The containment remedy would consist of a surface soil cap over the Former Process Area, containment of contaminated groundwater and NAPL with a sheet pile wall and extraction system, and construction of a replacement treatment plant for ongoing treatment of contaminated groundwater.

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