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Based on proposed industrial use, depth of contaminated soil, and the concrete cap that will be <br />installed as part of the Site construction, Kleinfelder will base further recommendations on <br />groundwater and soil vapor data. These data will indicate either: <br />Ongoing natural attenuation to concentrations below EPA Tap Water and Tier 1 <br />Groundwater ESLs with soil vapors below applicable screening levels. If groundwater and <br />soil vapor data are below applicable levels, Kleinf elder will recommend no further action. <br />Ongoing natural attenuation to concentrations above EPA Tap Water and Tier 1 <br />Groundwater ELSs with soil vapors below applicable screening levels. If Kleinfelder finds <br />that the average groundwater concentration is above applicable levels but soil vapor <br />concentrations are below levels, Kleinfelder will recommend no further action and will <br />petition for closure under low threat criteria. <br />Concentrations that do not indicate natural attenuation and/or soil vapor concentrations <br />above applicable screening levels. If Kleinfelder does not find evidence of natural <br />attenuation in these data, or if soil vapor concentrations are above applicable levels, <br />Kleinfelder will use PSGS data to conduct a soil removal action and then petition for <br />closure under low threat criteria. <br />OPERABLE UNIT 9 <br />Description <br />0U9 Corresponds to Sub-Recommendation 13.2, which concerns a former under-ground beet <br />flume. The Phase I identified potential for soil contamination via pesticides/herbicides. Phase II <br />samples were collected and analyzed for pesticides and herbicides (Figure 0U9-1). <br />Pesticides/Herbicides: Existing Data <br />Five soil samples were analyzed for organochlorine pesticides and chlorinated herbicides (Table <br />0U9-PH, soil samples 13-1 and 13-10 through 13-13). These analyses yielded 180 results. All <br />are ND, except for one 50 ug/kg detection of 2,4-DB and one 68 ug/kg detection of 4,4'-DDE. The <br />2,4-DB concentration is below the Industrial Threshold and Protection of Groundwater SSL. The <br />4,4'-DDE concentration is below the Industrial Threshold of 9,300 ug/kg but exceeds the <br />Protection of Groundwater SSL of 11 ug/kg. Most ND reporting limits have not been tabulated. <br />Those limits that have been tabulated are generally below Industrial Thresholds, except for those <br />associated with a single sample that had anomalously high reporting limits. <br />Pesticides/Herbicides: Recommendations <br />Kleinf elder recommends soil sampling at beet-flume depths of approximately 5 to 8 feet bgs to <br />confirm past results and collecting groundwater samples to assess potential groundwater <br />conditions. Based on experience with similar projects, Kleinfelder does not anticipate that <br />pesticide/herbicide soil concentrations identified in initial Phase ll work will have impacted <br />groundwater. <br />20173951.001A/SAC17R68420 Page 17 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