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

ASPECT CONSULTING PROJECT NO. AS190583A-08  MAY 21, 2025 FINAL 61 5.3 Development of Soil, Groundwater, and Air Preliminary Cleanup Levels Sections 5.3.1, 5.3.2, and 5.3.3 describe the derivation of PCLs for groundwater and soils, and air, respectively. In accordance with MTCA, PCLs are not set at concentrations less than the analytical practical quantitation limit (PQL) or natural background conditions. Points of compliance where the PCLs apply are discussed in Section 8. 5.3.1 Groundwater PCLs Because drinking water is not a practicable future use for groundwater at the Upland Area, the groundwater PCLs address the most stringent criteria for protection of the adjacent marine water body (East Waterway) and protection from VI into current and future structures (indoor air) on the property. However, for the purposes of the RI, groundwater cleanup levels based on drinking water (potable) use are applied if surface water quality criteria are not available, in accordance with WAC 173-340-720(6)(b)(i). Sections 5.3.1.1 and 5.3.1.2 describe the criteria for marine protection and protection against VI, respectively, which are incorporated into the groundwater PCLs. Section 5.3.1.3 describes the application of potable groundwater criteria. For arsenic, a Site-specific background concentration was established at 9 µg/L and this background value is used as the groundwater PCL for the RI (Appendix E). Based on an evaluation of the metals data from unfiltered groundwater samples versus filtered groundwater samples (“total” versus “dissolved” metals data, respectively) (Aspect, 2014e), Ecology determined that dissolved metals are the appropriate measurement to represent groundwater quality for the Upland Area. Consequently, for this RI/FS, the groundwater PCLs for metals apply to dissolved metals data. In accordance with the RI/FS Work Plan prepared prior to Ecology’s determination, the RI groundwater samples were analyzed for total metals, and unfiltered samples with total metal(s) detected at concentrations greater than the PCLs were subsequently also analyzed for dissolved metals. The concentration resulting from a total metals analysis will generally be greater than the concentration resulting from a dissolved metals analysis of the same groundwater sample. Therefore, for samples lacking a dissolved metals analysis, total metal(s) concentrations less than the PCL for that dissolved metal comply with the PCL. The data tables and mapping in this report apply that convention. The federal and state water quality criteria for ammonia are established for the un-ionized form (toxic form); therefore, groundwater PCLs apply to un-ionized ammonia not total ammonia. Table 5-1 presents the water quality criteria incorporated into the groundwater PCL derivation, and the resulting most stringent groundwater PCLs to be applied for the RI to the industrial use area of the Upland Area, including the City Utility Property and Norton Terminal. Table 5-2 presents the water quality criteria incorporated into the groundwater PCL derivation for the Warehouse Subarea, which considers protection of vapor intrusion for unrestricted land use in consideration of potential future repurposing of the warehouse for commercial uses. Note that Tables 5-1 and 5-2 only include constituents that were detected in samples of either soil or groundwater collected from the Upland Area;