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TABLE 8 <br /> ANALYSIS OF CHROMIUM CONCENTRATIONS AND REDUCTION POTENTIAL <br /> FORMER MARLEY COOLING TOWER SITE <br /> STOCKTON,CALIFORNIA <br /> Current Concentration Percent Change in Concentration Description of Trend for Ke Indicator Parameters <br /> Concentrations from p y Potential for <br /> Monitoring (µg/L) has been Further <br /> Well Maximum Below 50 /L Chromium Recommendation <br /> Total Chromium Total Chromium Rg Chromium Iron Manganese Total Organic Carbon Oxidation Reduction <br /> Sincea Potential Reductionb <br /> Chromium VI Chromium VI <br /> Background and Compliance Wells <br /> 1/2009(Before Variable,but below Revert to sitewide compliance monitoring <br /> MW-7 81 5.35 -85% -73% Stable below WQO Below WQO Low Positive Low a <br /> 2008) WQO program <br /> MW-201 14 10.7 -78% 0% 1/2009(Before Stable below WQO Near baseline Near baseline Low Positive Low Perform quarterly monitoring for total dissolved <br /> 2008) chromium and field parameters only per the MRP <br /> Revert to sitewide compliance monitoring <br /> MW-202 10 4.46 -70% 0% Before 2008 Stable below WQO Below WQO Baseline(ND) Low Positive Low a <br /> program <br /> Below WQO,Near Revert to sitewide compliance monitoring <br /> MW-210 5J 1 -71% -24% Before 2008 Stable below WQO Below WQO Low Positive Low a <br /> baseline program <br /> Below WQO Near Revert to sitewide compliance monitoring <br /> MW-302 <10 1.35 -86% -36% Before 2008 Stable below WQO baseline program Baseline(ND) Low Positive Low a <br /> MW-304 12 8.27 -66% -17% Before 2008 Stable below WQO Above baseline,above Baseline(ND) Low Positive Low Perform quarterly monitoring for total dissolved <br /> but near WQO chromium and field parameters only per the MRP <br /> Revert to sitewide compliance monitoring <br /> MW-401 <10 1.11 -55% 0% Before 2008 Stable below WQO Below WQO Baseline(ND) Low Positive Low a <br /> program <br /> MW-310 10 8.36 -78% 0% Before 2008 Stable below WQO Above baseline,above Baseline(ND) Low Positive Low Perform quarterly monitoring for total dissolved <br /> but near WQO chromium and field parameters only per the MRP <br /> MW-211 3J 1.96 -82% ° Below WQO,Near Below WQO,Near Revert to sitewide compliance monitoring <br /> -6/o Before 2008 Stable below WQO baseline baseline Low Positive Low programa <br /> MW-325 81 7.82 -74% 0% Before 2008 Stable below WQO Above baseline,above Baseline(ND) Low Positive Low Perform quarterly monitoring for total dissolved <br /> but near WQO chromium and field parameters only per the MRP <br /> Notes: <br /> a =Dates in parentheses represent chromium VI,if the date is different than for total chromium. <br /> 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. <br /> =Recommendation is based on completion of injections nearby and more than 2 years of chromium concentrations below the WQO. See the discussion in Section 8.0 and the decision logic diagram(Figure 5). <br /> a =Well would continue to be routinely sampled for chromium and other parameters as specified for the sitewide groundwater monitoring program in the MRP. <br /> =Well last sampled in 4th quarter 2011. <br /> Bold=Concentration greater than the WQO <br /> gg/L=microgram per liter <br /> J=Estimated laboratory value <br /> MRP=Monitoring and Reporting Program No.R5-2007-0126 issued by the California Regional Water Quality Control Board,Central Valley Region,September 13,2007. <br /> ND=not detected <br /> NM=not meaningful because the chemical has not been detected above the laboratory analytical reporting limit. <br /> WQO=water quality objective <br /> (Page 3 of 3) <br />