ARCHIVED REPORTS_2019-MAY 15 SITE ASSESSMENT REPORT

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15 May 2019 AGE Project No. 14-3002 Page 12 of 17 • Only one SVOC/PAH was detected in the waste samples analyzed. Bis (2-ethylhexyl) phthalate was detected in B18-5 at a concentration of 2.33 mg/kg; the concentration was significantly below the ESL (Table 4). • PCBs were detected in 5 of 6 waste samples at concentrations ranging from 0.202 mg/kg in B16-5 to 0.680 mg/kg in B20-5. PCBs were detected below the ESL and hazardous waste limit in the samples analyzed (Table 4). • TPH were not detected above laboratory reporting limits in any of the waste samples analyzed (Table 4). • Dioxin/Furans were detected in all twelve waste samples analyzed at TEQ concentrations ranging from 0.238 pg/g in mixed waste/soil sample B35-14 to 52.2 pg/g in waste sample B36-6. The dioxin/furans concentration detected in B36-6 (52.2 pg/g) was above the ESL of 22 pg/g, but well below the hazardous waste limit of 10,000 pg/g. However, the environmental screening level for dioxins is based on the congener 2,3,7,8-TCDD, and that specific congener was not detected above 22 pg/g in sample B36-6 (Table 4; Appendices G and H). No additional analytes were reported above laboratory detection limits in the waste samples analyzed. Analytical results of waste samples are summarized in Tables 2 through 4. PCB, dioxin/furan, and TPH concentrations are depicted in Figures 3 through 5 and in cross-sectional view in Figures 6 through 9. The laboratory reports (listed in Section 5.3.), QA/QC reports, and chain of custody forms are included in Appendix H. Laboratory EDF files will be QA/QC checked and uploaded to the State Water Board GeoTracker site. 5.5. ANALYTICAL RESULTS OF GROUNDWATER SAMPLES A total of nine grab groundwater samples were collected from borings B1, B6, B13, B16, B23, B28, B31, B35 and B40. Additionally, AGE assisted CVRWQCB staff with collecting a tenth groundwater sample from boring B18. Groundwater samples collected from borings B16 and B35 were collected near the center of Waste Cell No. 1 and Waste Cell No. 2, respectively, while the groundwater sample collected from B13 was collected in the general location of the former groundwater injection well utilized by the former power plant. Except for dioxin/furans, all groundwater samples collected by AGE were analyzed for the constituents listed in Section 3.3. Samples collected from B13, B16 and B35 were additionally analyzed for dioxin/furans. The following is a summary of the analytical results: • Arsenic was detected in the groundwater samples analyzed at concentrations ranging from 0.008 mg/l in B13 to 0.094 mg/l in B6. Arsenic was detected above the MCL of 0.01 mg/l in eight of the nine groundwater samples, but significantly below the hazardous waste limit (Table 5).