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

ASPECT CONSULTING 78 FINAL PROJECT NO. AS190583A-08  MAY 21, 2025  Removal of approximately 1,079 tons of soil contaminated with copper, mercury, and PCBs. The IA excavation areas are depicted on Figure 6-A1. For Unit A, data collected from within the Warehouse Subarea are compared to the PCLs derived for protection of commercial workers and data collected from outside of the Warehouse Subarea are compared to the PCLs derived for protection of industrial workers, as described in Section 5.3. The unexcavated area within the western portion of the Bunker C ASTs area is where Scott Paper conducted an independent soil cleanup in 1995, in conjunction with decommissioning of the fuel ASTs (Scott Paper, 1995b). The geotextile placed beneath import fill during the 1995 cleanup work was visible on the edges of the first IA excavation. There were no soil TPH exceedances detected in samples collected within that area during the Phase 2 ESA (Aspect, 2013a), or in the verification soil data collected on the excavation sidewalls surrounding that area (Figures 6-A2 and 6-A3). During the Phase 2 ESA, prior to the first IA, groundwater TPH exceedances were detected in well MW-3, but not in well MW-4; both wells are located within that unexcavated area. Large quantities of groundwater were pumped from the Bunker C ASTs excavation during the first IA, so the pre-IA groundwater data from this area are not representative of current conditions. During the first IA excavation, nonaqueous-phase liquid (NAPL) Bunker C oil was observed amongst wood pilings that historically supported one of the fuel oil ASTs (see photographs 5 and 6 in Appendix B to the IA Report; Aspect, 2015a). Residual NAPL was also observed within the former oil conveyance pipeline that was removed. The observed NAPL was removed as part of the first IA cleanup. A total of 170 verification soil samples were collected within the Bunker C ASTs excavation area for analysis as part of the first IA (Figure 6-A1). As part of the shoreline pipe plugging effort during the second IA, a fuel line was encountered during the removal of a stormwater catch basin west of the IA excavation area (Fuel Line W shown on Figure 6-A1). The fuel line was capped beneath the catch basin and determined to be an abandoned fuel-oil line that historically was connected to the Bunker C ASTs area (Aspect, 2021). The entire 60-foot length of fuel pipe was removed, and a total of 12 verification soil samples were collected from the sidewalls and base of the trench excavation completed to remove the pipe. Also, during the second IA, soil containing copper, mercury, and PCBs above their respective PCLs was removed from the OMS area to a total depth of 5 feet bgs. The excavation was limited to the south by the steep shoreline bank and a 36-inch-diameter wood stave pipe that is in the upper portion of that bank. A total of 21 verification soil samples were collected from the limits of the OMS area excavation (Aspect, 2021). In addition to sampling and analysis conducted for the two IAs, soil and groundwater samples were collected from 55 borings and monitoring wells completed within Unit A (Figure 6-A1). Drill bit refusal occurred during the drilling of proposed monitoring well REC1-MW-13, located inside the warehouse. The drill bit refusal prevented the