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

ASPECT CONSULTING PROJECT NO. AS190583A-08  MAY 21, 2025 FINAL 41 4 Remedial Investigation Activities In accordance with the RI/FS Work Plan (Aspect, 2013c) and subsequent Work Plan Addenda described in Section 4.2, soil, groundwater, intertidal porewater, and air sampling was conducted as part of the RI data collection program to assess the nature and extent of contamination in the Upland Area. Aspect subcontracted with a Washington- licensed resource protection well driller from Holt Services, Inc., to complete the soil borings and monitoring wells in accordance with the requirements of Chapter 173-160 WAC. Soil samples were obtained using direct-push drilling methods, and groundwater samples were obtained from monitoring wells using low-flow sampling techniques. Soil boring, monitoring well installation and development, and soil and groundwater sample collection were completed in accordance with the Sampling and Analysis Plan (SAP; Appendix A to the RI/FS Work Plan). For the RI characterization (2013–2017), a total of 88 borings and 44 new monitoring wells were completed. Six of the monitoring wells installed during the Phase 2 ESA and damaged during mill demolition were also decommissioned and replaced for groundwater sampling during the RI. In addition, collocated indoor air and sub-slab air samples were collected two times at three locations within the warehouse along with samples of ambient air from locations upwind of the warehouse. Over the course of four monitoring events of variable scope, samples of intertidal porewater and seepage were collected at ten locations, and water quality field parameters were collected at ten additional intertidal seepage locations, along the Upland Area shoreline. Demolition of the pulp/paper mill structures generated a very large quantity of concrete and brick demolition debris, most of which was crushed to produce CM and then graded as a surface veneer across roughly 32 acres of the Upland Area; all of the CM was subsequently removed in 2020 as confirmed by DEA and as discussed in Section 4.5. A substantial quantity of demolition debris was also profiled and disposed of off-Site, including 552 tons of hazardous waste disposed of at the Chemical Waste Management Subtitle C landfill in Arlington, Oregon, 6,884 tons of solid waste disposed of at Roosevelt Regional Subtitle D landfill in Roosevelt, Washington, and 52 tons of concrete disposed of at the CEMEX Glenwood Landfill in Everett Washington (subsequently purchased by Cadman Inc.). In addition, 8,437 tons of asphalt was separated and recycled at Granite Construction’s Smith Island Recycle facility in Everett, Washington, and a large quantity of metals (steel, copper, titanium, aluminum, stainless steel) was separated and recycled. The incorporation of the CM into the Site was conducted independently by K-C and was not part of the work to be performed under Agreed Order No. DE 9476. However, sampling of the demolition debris was included in the RI/FS Work Plan because it was introduced to the Site as a new exposed environmental medium during mill demolition. Following grading, 42 samples of the in-place CM (RM- series samples) were collected on a systematic grid in accordance with the RI/FS Work Plan. In addition, seven samples of stockpiled CM (CONC- series samples) were collected before the material was placed at the surface within the footprint of the Bunker C AST IA excavation area, providing 49 samples of the CM. Because that material was intended for use for backfill/grading in the