Laserfiche WebLink
chloroform in background well MW-6A is not believed to the result of a release from the <br /> landfill. <br /> 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, and are presented in Appendix D. Based on a comparison of the data obtained <br /> during the current monitoring period, the following analytes were found to exceed a CL: <br /> CONSTITUENT Concentration DMP Monitoring Wells <br /> LimitMW-6A- MW-7A- MW-8A MW-9A MW-913 MW-10A <br /> GENERAL CHEMISTRY(mg1l) <br /> Calcium 125.1 140 160 180 <br /> Chloride 269.2 470 600 <br /> Magnesium 75 78 110 <br /> H 6.47-8.02 6.38 6.30 <br /> Potassium 2.1 2.3 4.1 2.5 <br /> Total Dissolved Solids(TDS) 1600 2000 <br /> olatile Organic Compounds(µg11) <br /> hloroform 0.5 1.0 <br /> NOTES: (*)—Backgmund Well. <br /> Trend Analysis <br /> In order to evaluate changes In water quality in DMP wells at the French Camp Landfill, <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 Bicarbonate Chloride,Specific Conductance, Sulfate,TDS <br /> MW-8A None Apparent Calcium,Magnesium,Nitrate-N,Sodium <br /> MW-9A None Apparent None Apparent <br /> MW-913 Sulfate I pH <br /> MW-10A Chloride I Nitrate-N <br /> As shown above, CLs were exceeded for one or more constituents in the samples <br /> collected from wells MW-6A, MW-9A, MW-9 , and MW-10A. It should be noted, <br /> however,that with the exception of the chloride concentration measured in the sample <br /> collected from well MW-10A, none of the constituents that exceeded a CL exhibited a <br /> statistically significant increasing trend during the monitoring period. As shown in the <br /> time-series plots (Appendix D), concentrations of chloride measured in well MW-10A <br /> (600 mg/L) are generally similar to concentrations observed in this well since May 2001. <br /> In January 2005 a No Release Demonstration( ) for groundwater monitoring well <br /> MW-l0A was performed (Herst, 2005) in response to CL exceedances of chloride and <br /> TDS. The NRD concluded that French Camp Landfill, located within the central <br /> Stockton area, has been impacted by saltwater intrusion and the elevated chloride and <br /> DA2009-0018TC_t SA09.doc <br /> Geologic Associates <br />