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

ASPECT CONSULTING PROJECT NO. AS190583A-08  MAY 21, 2025 FINAL 59 standard Method B exposure assumptions and may be applied as cleanup levels as part of the FS and CAP. If the warehouse is redeveloped for commercial use, remediation levels for soil gas and indoor air media based on adult commercial worker exposure (not residential) will be applied for assessing the protectiveness of the remedy. However, the cleanup levels for soil gas and indoor air will be established under Method B for the commercial worker scenario. The development of PCLs and commercial-use remediation levels is discussed in Section 5.3. 5.1.2 Water Use The Upland Area is within the City’s municipal water service area and is supplied with potable water from the City. There are no operational groundwater supply wells on the property; water wells historically used for the mill’s water supply have been properly decommissioned. The availability of municipal water supply, and City ordinances requiring entities within the water service area to connect to the municipal water supply, effectively preclude the use of groundwater within the Upland Area as a potable water supply. Ecology has determined that groundwater within the Upland Area is not a reasonable future source of drinking water given proximity to marine surface water (also see Section 5.2.2). 5.2 Potential Receptors and Exposure Pathways An exposure pathway describes the mechanisms by which human or ecological exposure to contaminants can occur assuming no remedial action or protective control is in place. An exposure pathway is considered complete if a human or ecological receptor can be exposed to a contaminant via that pathway. Potential pathways for receptors to be exposed to Upland Area contaminants in soil, groundwater, and the marine environment (through groundwater discharge) are outlined below. As discussed in Section 1, the Site includes a portion of the East Waterway termed the In-Water Area, and there are potential exposure pathways associated with sediment and surface water in the In-Water Area; however, those pathways will be addressed as part of the RI/FS for the East Waterway. 5.2.1 Soil Exposure Pathways Current and future potentially complete exposure pathways for soil under the planned future site use are identified below:  Worker 21 incidental ingestion and dermal contact with contaminants in soil;  Worker exposure through inhalation of soil contaminants (as particulates) that have migrated to air as windblown or fugitive dust; and  Worker exposure through inhalation of soil contaminants (as soil vapor) that have migrated to indoor and/or outdoor air. 21 “Worker,” as referenced under the Soil Exposure Pathways section, includes both adult industrial workers in the Upland Area industrial-use area and adult commercial workers in the Warehouse Subarea if it is redeveloped for commercial use.