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TABLE 9 ANALYSIS OF CHROMIUM CONCENTRATIONS AND REDUCTION POTENTIAL FORMER MARLEY COOLING TOWER SITE STOCKTON,CALIFORNIA Page 3 of 3 Percent Change m Description of Trend for Ke Indicator Parameters Fourth Quarter 2012 Concentration p � Y Potential for Monitoring Concentration(µ Concentrations fromg/L) has been Further Maximum Oxidation Reduction Recommendation` Well Total Chromium Total Chromium Below 50µg/L Chromium Iron Manganese Total Organic Carbon Potential Chromium Chromium VI Chromium VI Since e Reduction Background and Compliance Wells 1/2009(Before Revert to sitewide compliance monitoring MW-7 6J NA -89% -75% 2008) Stable below WQO Near baseline Near baseline Low Positive Low programd MW-201 14 NA -78% -21% 1/2009(Before Stable below WQO Near baseline Near baseline Low Positive Low Perform quarterly monitoring for total dissolved 2008) chromium and field parameters only per the MRP MW-202 7J NA -79% -1% Before 2008 Stable below WQO Near W and Baseline(ND) Low Positive Low Revert to sitewide compliance monitoring baselinin e program Below WQO,Near Revert to sitewide compliance monitoring MW-210 4J NA -76% -29% Before 2008 Stable below WQO baseline program Below WQO Low Positive Low d Below WQO,Near Revert to sitewide compliance monitoring MW-302 4J NA -89% -52% Before 2008 Stable below WQO Baseline(ND) Low Positive Low d baseline program MW-304 4J NA -69% -17% Before 2008 Stable below WQO Above baseline and Baseline(ND) Low Positive Low Perform quarterly monitoring for total dissolved WQO chromium and field parameters only per the MRP Revert to sitewide compliance monitoring MW-401 4J NA -100% 0% Before 2008 Stable below WQO Below WQO Baseline(ND) Low Positive Low d program MW-310 91 NA -80% -6% Before 2008 Stable below WQO Above baseline,above Baseline(ND) Low Positive Low Perform quarterly monitoring for total dissolved but near WQO chromium and field parameters only per the MRP Below WQO,Near Below WQO,Near Revert to sitewide compliance monitoring MW-211 3J NA -82% -1% Before 2008 Stable below WQO Low Positive Low d baseline baseline program MW-325 81 NA -74% -29% Before 2008 Stable below WQO Above baseline,below Baseline(ND) Low Positive Low Perform quarterly monitoring for total dissolved WQO chromium and field parameters only per the MRP Notes: a =Dates in parentheses represent chromium VI,if the date is different than for total chromium. b =Potential for further chromium reduction is based on the presence of iron,manganese,total organic carbon,and depressed oxidation reduction potential readings,as discussed by chemical in Section 4.0. ° =Recommendation is based on completion of injections nearby and more than 2 years of chromium concentrations below the WQO. Seethe discussion in Section 8.0 and the decision logic diagram(Figure 5). d =Well would continue to be routinely sampled for chromium and other parameters as specified for the sitewide groundwater monitoring program in the MRP. Bold=Concentration greater than the WQO µg/L=microgram per liter J=Estimated laboratory value MRP=Monitoring and Reporting Program No.R5-2007-0126 issued by the California Regional Water Quality Control Board,Central Valley Region,September 13,2007. ND=not detected NM=not meaningful because the chemical has not been detected above the laboratory analytical reporting limit. WQO=water quality objective