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ASPECT CONSULTING <br />PROJECT NO. AS190583A-08  MAY 21, 2025 FINAL 37 <br /> <br /> Investigated soil and groundwater quality at the Central Maintenance Shop (also <br />known as the salvage warehouse) which, according to the 1994 facility drawing, <br />included a PCB-waste accumulation area on its south side. This structure is also <br />labeled as the Auto Shop on the 1996 facility drawing (see Appendix C to RI/FS Work <br />Plan; Aspect, 2013c). The investigation identified total PCBs in shallow soil beneath <br />the building at concentrations greater than the unrestricted screening level and less <br />than the industrial soil screening level, and groundwater petroleum hydrocarbon and <br />PAH concentrations (suggestive of creosote) greater than respective groundwater <br />screening levels. PCBs were not detected in either soil sample collected from the <br />General Fill boring installed on the south side of the Shop, where PCB wastes were <br />reportedly accumulated. <br /> Investigated soil and groundwater quality at the Old Machine Shop. The investigation <br />identified total PCBs and lead in shallow soil beneath the building at concentrations <br />greater than unrestricted screening levels and less than industrial soil screening levels, <br />and dissolved nickel and ammonia concentrations greater than respective groundwater <br />screening levels. In addition, copper was detected at 265 mg/kg in one soil sample, <br />above a preliminary unrestricted soil screening level based on leachability to <br />groundwater (defaults to 36 mg/kg natural background soil concentration); however, <br />groundwater copper concentrations in the Old Machine Shop monitoring well were <br />below the conservative groundwater screening level. <br /> Investigated soil and groundwater quality in the Boiler/Baghouse Area. Metals <br />(arsenic, copper, lead, mercury, and zinc), diesel- and oil-range TPH, naphthalene, <br />carcinogenic polycyclic aromatic hydrocarbons (cPAHs), and dioxins/furans were <br />detected in one or more soil samples at concentrations greater than respective <br />unrestricted screening levels; lead concentrations also exceeded the industrial soil <br />screening level. The groundwater sample from well Boiler-MW-1 contained only a <br />marginal exceedance for total cPAHs, as well as dissolved copper concentrations <br />greater than its screening level. The high concentrations of Bunker C fuel oil in soil in <br />this area were interpreted to be associated with the adjacent Bunker C fuel oil USTs <br />No. 71/72/73, possibly indicating a subsurface pipeline from the USTs to the boiler. <br />K-C recommended removal of the oil-contaminated soil and subsurface fuel <br />pipeline(s), if present, as well as removal of metals-contaminated soil in this area, in <br />conjunction with the USTs No. 71/72/73 IA. <br /> Investigated soil and groundwater quality at the Hazardous Waste Cage located on the <br />north side of the Log Pond fill. The investigation identified lead in one soil sample <br />greater than the unrestricted soil screening level and less than the industrial screening <br />level; detected arsenic and total cPAH concentrations in soil also exceeded respective <br />unrestricted soil screening levels. Soil concentrations of copper, nickel, and zinc also <br />exceeded respective unrestricted soil screening levels based on groundwater <br />protection—screening levels that are equal to natural background concentrations and <br />thus very conservative. Concentrations of dissolved arsenic, copper, and nickel were <br />detected in groundwater at concentrations greater than respective groundwater <br />screening levels.