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Concentration Limits <br /> For DMP monitoring wells at the French Camp Landfill, concentration limits(CLs)are <br /> used for the water quality protection standards ( QPS). The CLs shown in Table 2 were <br /> calculated by Herst &Associates using Sanitas, a state-approved statistical software <br /> program, using historical data from background wells MW-6A and MW-7A, and are <br /> presented in Appendix D. Based on a comparison of the data obtained during the third <br /> quarter 2007 monitoring period, the following analytes were found to exceed a CL: <br /> CONSTITUENT Concentration IDMP Monitoring Wells <br /> 1-1 Limit MW-6A* MW-7A* MW-8A I MW-9A I MW-9B MW-10A <br /> GENERAL CHEMISTRY(mg/l,except as noted) <br /> H(pH units) 6.71-7.95 6.69 1 6.61 6.48 <br /> alcium 133.3 150 200 <br /> Chloride 370 460 510 <br /> Magnesium 75 110 <br /> Potassium 1 2.065 2.1 3.9 2.6 <br /> OLATILE ORGANIC COMPOUNDS(pg/l) <br /> rict lorofluoromethane 1 0.50 0.72 <br /> NOTES: (*)–Backgmund Well. <br /> Trend Analysis <br /> In order to evaluate changes in water quality in DMP wells at the French Cam Landfill <br /> g q Y P <br /> historical groundwater data were evaluated using Sen's Slope trend analyses to determine <br /> if significant increasing or decreasing trends were evident. Trend analyses, performed by <br /> Herst&Associates, are presented in Appendix D and summarized below. <br /> Well Number Increasing Trends Decreasing Trends <br /> MW-6A None Apparent pH <br /> MW-7A None Ap arent Specific Conductance,Sulfate,TDS <br /> MW-8A None Apparent Nitrate-N <br /> MW-9A pH,Potassium None Apparent <br /> MW-913 Sulfate None Apparent <br /> MW-10A I Chloride,Specific Conductance Nitrate-N <br /> As shown above, CLs were exceeded for inorganic constituents in the samples collected <br /> from wells MW-6A, MW-9A, MW-913 and -10A, and with the exception of the <br /> chloride concentration measured in well MW-10A,none of the constituents that exceeded <br /> a CL exhibited a significant increasing trend during the third quarter 2007 monitoring <br /> period. In response to statistical exceedances of chloride and TDS identified in samples <br /> from well MW-l0A during the second quarter 2004, a No Release Demonstration(NRD) <br /> for groundwater monitoring well MW-l0A was performed(GLA,2003). The NRD <br /> concluded that French Camp Landfill, located within the central Stockton area, has been <br /> impacted by saltwater intrusion and the elevated chloride and TDS concentrations <br /> measured in well MW-l0A are believed to be the result of this condition and not the <br /> result of landfill-related impacts. <br /> D:12007-0M\FC_mm07.doc <br /> Geologic Associates <br />