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OU 6 Work Plan <br />Spot <br />Check <br />Slide <br />Hammer <br />Passive <br />Soil Gas <br />Survey <br />Soil Vapor Soil Hydropunch <br />Explorations <br />Samples 12 (100%) <br />Analyses <br />For each of the 12 Phase II results noted in the Existing Data sections, Kleinfelder will assess the <br />initial Phase II paper-copy laboratory reports and tabulate the associated laboratory <br />reporting/detection limits and screening levels. Kleinfelder will provide these data to the Board for <br />its review. <br />OPERABLE UNIT 7 <br />Description <br />OU 7 Corresponds to Sub-Recommendation 12.5, which concerns an acid/caustic storage area. <br />The Phase I identified potential for soil contamination via leaks/spills of acid and corroded metal <br />compounds. Phase II samples were collected and analyzed for acid- and metal-related <br />compounds. <br />Acidity: Existing Data <br />Fourteen soil samples were analyzed for pH and alkalinity (Table 0U7-A, soil samples 12-8 <br />through 12-16). Alkalinity ranges from ND to 152, with an average of 48.6, and pH ranges from <br />7.27 to 9.67, with an average of 8.03. These values do not indicate leaks of acidic or basic <br />solutions. We therefore recommend no further action <br />Acidity: Recommendations <br />Existing Phase II acidity data do not indicate conditions beyond natural background variance. <br />Kleinfelder therefore recommends no further action. <br />Metals: Existing Data <br />Fourteen soil samples were analyzed for CAM 17 metals (Table 0U7-M, soil samples 12-8 <br />through 12-16). Concentrations are below Industrial Thresholds except for arsenic, which is noted <br />at concentrations of 1 mg/kg, exceeding the Industrial Threshold of 0.36 mg/kg. Moreover, <br />arsenic, cobalt and mercury results and arsenic and thallium laboratory reporting limits exceed <br />Protection of Groundwater SSLs. Kleinfelder has analyzed these metal concentrations against <br />those from OU 1 (Table OU1-M, soil samples 5-1 and 5-7) and OU 11 (Table OU11-M, soil <br />samples 6-6 through 6-13). Metal concentration distributions from OU 1 and OU 7 are very similar, <br />20173951.001A/SAC17R68420 Page 13 of 26 November 2, 2017 <br />© 2017 Kleinfelder www.kleinfelder.com <br />KLEINFELDER 2882 Prospect Park Dr., Suite 200. Rancho Cordova, CA 95670 p I 916.366-1701 f I 916.366-7013