3815_PGSF WMVD Pkg 2_Vol 4-2_03.03.2026_BXWA_Certified

ASPECT CONSULTING 90 FINAL PROJECT NO. AS190583A-08  MAY 21, 2025 6.5.2 Unit B The explorations and IA areas within Unit B, including IA compliance soil sample locations, are depicted on Figure 6-B1. For current conditions following the IA, the constituents detected in one or more samples of Unit B media at concentrations exceeding their respective industrial PCLs are as follows:  TPH-D+O in soil and groundwater  Total cPAHs (TEQ) in soil and groundwater  Arsenic, copper, lead, mercury, nickel, and zinc in soil and groundwater  Naphthalene in soil and groundwater  The following SVOCs in groundwater at a single location for each: 2-methylnaphthalene, 2,4,6-trichlorophenol, dibenzofuran, fluorene, and pentachlorophenol  Vinyl chloride in groundwater  Total PCBs in soil  Un-ionized ammonia in intertidal porewater Constituents that were not detected at concentrations greater than the industrial PCLs in soil or groundwater samples collected within Unit B include TPH-G, BTEX, dioxins/furans, metals, VOCs, and SVOCs, which are not included in the list above. The sample locations for constituents detected at concentrations exceeding the PCLs in Unit B are presented on Figures 6-B2 through 6-B18. The data for constituents detected at concentrations exceeding the PCLs are summarized by constituent group in the following subsections. 6.5.2.1 Total Petroleum Hydrocarbons and PAHs Gasoline-range TPH and BTEX were not detected above the PCLs in soil or groundwater samples collected from within Unit B (Tables 6-13 and 6-14). Following the two IAs, concentrations of TPH-D+O (as Bunker C fuel oil) remain in soil and groundwater above the PCLs only within the USTs 71, 72, 73 IA area of Unit B (Figure 6-B2). 6.5.2.1.1 Soil TPH and PAH Data Within Unit B, seven IA areas focused on the removal of TPH-contaminated material: the Rail Car Dumper area, the BA-MW-6 area, the UST 70 area, the Heavy Duty Shop Sump area, the USTs 71, 72, 73 area, the REC2-MW-5 area, and the Digesters Trench area (Figure 6-B1). While the CMS area was remediated in the second IA primarily to address PCBs in soil that were a source to groundwater, it also removed localized naphthalene exceedances in groundwater and segments of historical Bunker C fuel lines with associated soil contamination. The CMS area excavation was completed over a total duration of approximately 7 weeks, during which time, construction dewatering was conducted frequently to remove accumulated groundwater to facilitate soil removal. The groundwater removed from the CMS area excavation was combined with groundwater extracted from other excavations happening concurrently during the second IA, so the