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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 (WQPS). 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 first <br /> quarter 2006 monitoring period, the following analytes were found to exceed a CL: <br /> CONSTITUENT Concentration IDMP Monitoring Wells <br /> LImit MW-6A*I MW-7A*I MW-8A I MW-9A I MW-9B I MW-10A <br /> GENERAL CHEMISTRY(mg/l,except as noted) <br /> Barium 0.4939 0.880 <br /> Bicarbonate 1000 1100 <br /> cium 110 150 150 150 <br /> bioride 239.3 460 520 <br /> iteate as Nitrogen 19.3 20 <br /> otassium 2.212 3.5 <br /> ific Conductance 2700 3300 , <br /> ulfate 180 220 280 <br /> Total Dissolved Solids 1600 1 1700 <br /> VOLATILE ORGANIC COMPOUNDS(µ911) <br /> 1 -Dichlomedwe 1 0.25 0.50 <br /> NOTES: (*)-Background 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 Barium pH <br /> MW-7A None Apparent Sulfate <br /> MW-8A Specific Conductance Nitrate-N , <br /> MW-9A None Apparent None Apparent <br /> MW-9B Sulfate None Apparent <br /> MW-10A Chloride,Specific Conductance Nitrate-N <br /> As shown above, CLs were exceeded for one or more constituents in the samples <br /> collected from wells MW-8A, MW-9A,MW-9B and MW-10A. Of note, with the <br /> exception of the chloride and specific conductance values measured in the sample <br /> collected from well MW-10A,none of the constituents that exceeded a CL exhibited a <br /> significant increasing trend during the first quarter 2006 monitoring period. In January <br /> 2005 a No Release Demonstration(NRD) for groundwater monitoring well MW-l0A <br /> was performed(Herst, 2005)in response to CL exceedances of chloride and TDS. The <br /> NRD concluded that French Camp Landfill,located within the central Stockton area,has <br /> been 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 /> D:0003_021\FC_wKdoc <br /> 4 Geologic Associates <br />