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In addition, two Hydropunch samples were collected during Phase II sampling (Table OU1-M, 5- 1-HP and 5-7-HP). Both were analyzed for CAM 17 metals. Detections include barium (350 to 440 ug/L), nickel (20 ug/L), and zinc (14 to 60 ug/L). These concentrations are below EPA Tap Water and Tier 1 Groundwater ESLs, except for nickel, which exceeds the Tier 1 Groundwater ESL of 8.2 ug/L. Metals: Recommendations While nickel concentration marginally exceed the Tier 1 Groundwater ESL, as a whole, soil and groundwater analyses strongly indicate metal concentration in soil likely represent natural background conditions and pose minimal threat to groundwater. Kleinfelder recommends investigation to confirm natural background concentrations, as Hydropunch data are not available to confirm groundwater conditions for OU 7, for which metal concentrations in soil are also a concern. It is anticipated that OU 1 metal concentrations will fall within natural background concentrations and therefore no further action will be recommended. Kleinfelder also recommends distinguishing chromium results and report chromium III and VI, as per the Board's request. Based on existing total chromium data, it is anticipated that chromium (VI) concentrations should not exceed ESLs. Petroleum/Solvents: Existing Data Four soil samples were collected and analyzed for Total Extractable Petroleum Hydrocarbons, Fuel Fingerprint (EPA 8015M), Industrial Solvents, Ethylene Glycol, Volatile Organic Compounds (VOCs) by GCMS (EPA 8240), and semi-VOCs (EPA 8270) (Table OU1-P, soil samples 5-1 and 5-7). These analyses yielded 354 petroleum-related results, of which all are reported below laboratory detection limits (ND). Most laboratory reporting limits are not stored in a digital format (tabulated) and are only noted in the original paper-copy laboratory result reports. Those that are tabulated are below Industrial Thresholds but typically above Protection of Groundwater SSLs (Table 1-P). In addition, two Hydropunch samples were collected and analyzed for Total Extractable Petroleum Hydrocarbons (TPH), Fuel Fingerprint (EPA 8015M), Industrial Solvents, Ethylene Glycol, VOCs by GCMS with Tentatively Identified Compounds (TICs) (EPA 8240), and semi-VOCs with TICs (EPA 8270) (Table OU1-P, hydropunch samples 5-1-HP and 5-7-HP). All results are ND, except for TPHueh (84 ug/L, carbon range C13 to C32) and Bis(2-ethylhexyl)phthalate (310 ug/L). The TPHueh concentration is below the applicable EPA Tap Water and Tier 1 Groundwater ESLs, but the Bis(2-ethylhexyl)phthalate concentration exceeds the EPA Tap Water RSL of 5.6 ug/L and the Tier 1 ESL of 4.0 ug/L. Reporting limits are tabulated for TPHd and TPHueh. These limits are below EPA Tap Water and Tier 1 Groundwater and ESLs. Based on the TPHueh and Bis(2-ethylhexyl)phthalate detections, the County requested additional sampling and analyses. Two additional borings were drilled and Hydropunch samples collected about 20 feet downgradient of Boring 5-1, where these compounds were detected. Soil samples were analyzed for Total Extractable Petroleum Hydrocarbons, Fuel Fingerprint (EPA 8015M) and Semi-VOCs (EPA 8270) (Table OU1-P, soil sample 5-1A). All results are ND. Groundwater Hydropunch samples were analyzed for Total Extractable Petroleum Hydrocarbons, Fuel Fingerprint (EPA 8015M) and Semi-VOCs (EPA 8270) (Table OU1-P, hydropunch sample 5-1A- HP). All results are ND. 20173951.001A/SAC17R68420 Page 3 of 26 November 2, 2017 © 2017 Kleinfelder www.kleinfelder.com KLEINFELDER 2882 Prospect Park Dr., Suite 200, Rancho Cordova, CA 95670 p I 916.366-1701 f I 916.366-7013