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Prop 65 Notification - 2 - 30 July 2021 <br /> Stockton Municipal Airport <br /> PFAS <br /> Health Risk, Tapwater Cancer Risk" to be most appropriate. For soil ESLs, Central <br /> Valley Water Board staff determined "Leaching to Groundwater: Drinking <br /> Water" to be most appropriate. <br /> PFOA and PFOS concentrations were found above the "Direct Exposure Human Health <br /> Risk, Tapwater Cancer Risk" ESLs in groundwater (0.54 nanograms per liter [ng/L] and <br /> 1.7 ng/L, respectively) in all three temporary groundwater monitoring wells (Table 1). <br /> Grab groundwater results from temporary monitoring wells are presented in Table 1 <br /> below. Cells highlighted in yellow indicate exceedances of the respective ESL. <br /> Table 1. "PRA 2" Analytical Results Summary for PFOA and PFOS in <br /> Groundwater <br /> Table 1: "PRA 2"Analytical Results Summary for PFOA and PFOS in Groundwater n /L <br /> Groundwater PFOA PFOS <br /> Sample Identification PRA Sample Collection Date Direct Exposure ESL Direct Exposure ESL <br /> 0.54 1.7 <br /> TW-1 2 6/24/2020 100 17 <br /> TW-2 2 6/25/2020 31 5.8 <br /> TW-3 2 6/25/2020 1 3.9 3.2 <br /> J-Estimated Value <br /> ng/L=Nanogram per Liter <br /> PFOA=Perfluorooctanoic acid <br /> PFOS=Perfluorooctane sulfonate <br /> PRA-Potential Release Area <br /> ESL=San Francisco Bay Regional Water Quality Control Board Environmental Screening Level <br /> The PFOA and PFOS concentrations were found above the ESL for "Leaching to <br /> Groundwater" for soil (0.097 micrograms per kilogram [fag/kg] and 0.70 pg/kg, <br /> respectively) in two soil borings for PFOA and six soil borings for PFOS (Table 2). Cells <br /> highlighted in yellow in Table 2 indicate exceedances of the respective ESL. <br /> Table 2. "PRA 2" Analytical Results Summary for Select Wells with PFOA and <br /> PFOS in Soil <br /> Table 2: "PRA 2"Analytical Results Summary for Select Wells Soil /k <br /> with PFOA and PFOS in Soil PFOA PFOS <br /> Sample Identification PRA Sample Collection Date Leaching to Leaching to <br /> Groundwater: Drinking Groundwater: Drinking <br /> Water ESL Water ESL <br /> 0.097 0.40 <br /> B-1 5' 2 6/24/2020 <0.20 0.94 J <br /> B-4 @ 1' 2 6/24/2020 <0.20 0.36 J <br /> B-8 @ 1' 2 6/24/2020 2.9 6.9 <br /> B-8 5' 2 6/24/2020 <0.20 0.21 J <br /> B-9 @ 1' 2 6/24/2020 <0.20 0.43 J <br /> B-10 a 1' 2 6/24/2020 <0.20 0.51 J <br /> TW-1 @ 1' 2 6/24/2020 <0.20 0.23 J <br /> TW-2 a 1' 2 6/25/2020 <0.20 1.7 <br /> TW-3 @ 1' 2 6/25/2020 1.4 41.0 <br /> TW-3 5' 2 6/25/2020 0.53 J 4.5 <br /> J=Estimated Value <br /> pg/Kg=Microgram per Kilogram <br /> PFOA-Perfluorooctanoic acid <br /> PFOS=Perfluorooctane sulfonate <br /> PRA=Potential Release Area <br /> ESL=San Francisco Bay Regional Water Quality Control Board Environmental Screening Level <br /> Another area of concern investigated in the Preliminary Site Investigation is the Wash <br /> Rack ("PRA 1"). Groundwater samples from this area also had PFOS and PFOA <br /> concentrations above ESLs (Table 3). The temporary groundwater monitoring wells <br /> were installed within 5,000 feet of seven water supply wells (101332, 101333, <br /> 01 S07E05C001 M, 01 S07E06B001 M, 01 N07E31 Q001 M, USGS-375326121145901 and <br />