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ASPECT CONSULTING <br />50 FINAL PROJECT NO. AS190583A-08  MAY 21, 2025 <br />(TPH-Gx), diesel- plus oil-range total petroleum hydrocarbons (TPH D+O) with silica gel <br />cleanup, semivolatile organic compounds (SVOCs) with low-level polycyclic aromatic <br />hydrocarbons (PAHs), volatile organic compounds (VOCs), priority pollutant metals, and <br />polychlorinated biphenyl (PCB) Aroclors. PCB congener analysis was subsequently <br />performed on the three soil samples with the highest total PCB Aroclor concentrations. <br />Based on observations from the geophysical survey and confirmatory soil <br />borings/trenches, five new monitoring wells were installed at targeted locations, as <br />outlined in Aspect (2017c), and approved by Ecology. Groundwater samples from the new <br />wells and the existing four wells 18 within the Log Pond footprint were collected in July <br />2017 and analyzed for TPH-Gx, TPH D+O with silica gel, SVOCs with low-level PAHs, <br />VOCs, dissolved priority pollutant metals, PCB congeners, ammonia, dissolved sulfide, <br />and (using DGT methodology) free sulfide. In conjunction with the July 2017 <br />groundwater sampling, groundwater field parameter measurements were also completed in <br />45 additional wells (65 wells total) to support evaluation of groundwater pH changes over <br />time. Also in conjunction with the July 2017 groundwater sampling, a snapshot set of <br />water levels were collected from the nine wells within the Log Pond footprint and 11 wells <br />located around the perimeter of the Log Pond to provide supplemental water level data to <br />assess groundwater flow directions and groundwater continuity between the Log Pond fill <br />and the fill outside of it. <br />In addition, because sampling of intertidal porewater/seeps cannot be conducted along the <br />Log Pond shoreline because it is armored with rip rap, surface water samples were <br />collected in three locations (LP-SW-1, LP-SW-2, and LP-SW-3) along the shoreline of the <br />Log Pond in late July 2017. The surface water samples were analyzed for dissolved <br />metals, ammonia, dissolved sulfide, and free sulfide by DGT methodology. The DGT <br />sampler at the LP-SW-2 location was damaged during deployment, preventing collection <br />of free sulfide data for that location. During this sampling, a DGT sample of sediment <br />porewater at the PW-5 location was also collected for analysis of free sulfide. <br />Finally, slug testing to estimate hydraulic conductivity was conducted in eight wells in the <br />Log Pond footprint, as described in Section 2.4.4.2.3. <br />4.3 Second Interim Action (2020) <br />Between May and November 2020, Ecology and K-C executed an amendment to the <br />Agreed Order to allow completion of a second IA. K-C and Ecology agreed to undertake <br />the second IA to remove additional contaminated soils and associated groundwater with a <br />primary goal to control sources of leachable contaminants to groundwater while the rest of <br />the Upland Area MTCA process proceeds. <br />A Work Plan for Second Interim Action (Aspect, 2019b; 2019 IA Work Plan) was <br />prepared as Exhibit A to the Agreed Order amendment, which went through a 30-day <br />public comment period prior to Ecology approval and finalization. The 2019 IA Work <br />Plan presented the approach to remove impacted soil from nine areas of the Site, as well as <br /> <br />18 Well HW-MW-1, installed at the hazardous waste cage within the Log Pond footprint, was <br />decommissioned during mill demolition so was not available for sampling.