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Geosyntec <br /> consultants <br /> Control Review Checklist attached in front of the laboratory report. The Data Quality <br /> Control Review Checklist and laboratory report are provided in Appendix B. <br /> 4.5 Discussion and Conclusions <br /> Data collected as part of this Limited Phase II ESA show that soil beneath the Site is not <br /> impacted by organochlorine herbicides or organochlorine pesticides at concentrations <br /> that exceed the CHHSLs for commercial/industrial land use (Cal EPA, 2005). <br /> Constituent concentrations in groundwater exceed established screening levels as <br /> discussed above in Section 4.3; however, the results are generally consistent with the <br /> known groundwater impacts associated with the former Spreckels Sugar Plant. <br /> Chloride, nitrate as N, sulfate, sodium, bicarbonate, and TDS concentrations reported in <br /> the grab groundwater samples collected at the Site were generally within one order of <br /> magnitude relative to the constituent concentrations reported in groundwater collected <br /> from the former offsite well, MW-3R, in 2005. Dissolved metals concentrations were <br /> not reported for MW-3R (except for sodium); however, reported dissolved metals <br /> concentrations obtained during this investigation are consistent with concentrations that <br /> would be expected given the areas past use by the former Spreckels Sugar Plant. <br /> Arsenic concentrations are also consistent with reported background concentrations for <br /> the City of Manteca(City of Manteca, 2012, 2013). <br /> Groundwater impacts beneath the Site were present in both upgradient (GSB-3) and <br /> downgradient(GSB-1 and GSB-2) sample locations. In general,the highest constituent <br /> concentrations were reported in groundwater collected from upgradient sample location, <br /> GSB-3. Specifically, the highest reported concentrations of metals (including barium, <br /> calcium, iron, magnesium, manganese, and sodium), alkalinity, bicarbonate alkalinity, <br /> and ammonia were reported in the groundwater sample collected from GSB-3. The <br /> greatest concentrations of chloride, nitrate as N, sulfate, potassium, and TDS were <br /> reported in the downgradient sample location, GSB-2. The lowest reported constituent <br /> concentrations were generally reported in downgradient sample location, GSB-1, with <br /> the exception of arsenic, which was reported at 0.018 mg/L at this location. These data <br /> demonstrate that the impacts reported beneath the Site are not caused or exacerbated by <br /> current Site activities. As such, additional investigation is not warranted. <br /> Phase II ESA_1351 Dupont_FINAL_12302013 <br /> 9 1/2/14 <br />