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® 5.4 DETECTION MONITORING PROGRAM Fourth quarter 2006 field and laboratory results for DMP monitoring wells (MW-6A, MW-7A,MW-8A, MW-9A, MW-9B, andMW-lOA) are summarized in Table 2 and time-series plots are presented in Appendix D. As shown in the time-series plots,the general chemistry and metals constituents are generally consistent with historical concentrations. Organic results indicate that excluding suspected field/laboratory contaminants, a trace level concentration of 1,2-dichloroethane (1,2-DCA)was measured in the sample collected from well MW-9B and concentrations of trichlorofluoromethane (TCFM)was detected above the practical quantitation limit(PQL)in the sample collected from well MW-9A. Pursuant to WDR Order No. R5-2004-0159 Section E(19)(b)(2) a non-statistical indication of a release from well -9A has been verified and the RWQCB was immediately notified of the release. Since TCFM is a common constituent found in landfill gas and the final cover was recently completed at the site, Forward has proposed quarterly soil-pore gas monitoring in perimeter soil-pore gas probes for fixed gases (carbon dioxide, oxygen,nitrogen, and ane) and VOCs for the next year to evaluate the significance of landfill gas at the site. Concentration Limits For DMP monitoring wells at the French Camp Landfill, concentration limits (CLs) are ® used for the water quality protection standards QPS). The CLs shown in Table 2 were calculated by Herst &Associates using Sanitas , a state-approved statistical software program,using historical data from background wells MW-6A and MW-7A, and are presented in Appendix D. Based on a comparison of the data obtained during the fourth quarter 2006 monitoring period,the following analytes were found to exceed a CL: CONSTITUENT Concentration I DMP Monitorin wells Limit -6A*I MW-7A*I MW-SA I MW-9A I MW-9B MW-l0A GENERAL CHEMISTRY(nWA,except as noted) Barium 0.5165 NA 0.79 Calcium 148.6 NA 150 Chloride 370 NA 460 Ma esium 75 NA 76 Potassium 2.022 NA 3.6 2.4 VOLATILE ORGANIC COMPOUNDS(pg/1) romoforin 0.50 2.8 1 NA 1 1.4 1.2 bromochloromethane 0.50 1.4 1 NA 0.85 0.97 richlomfluoromethane 0.50 NA 1.7 NOTES: (*)—Background Well. NA—Not Analyzed. Trend Analysis In order to evaluate changes in water quality in DMP wells at the French Camp Landfill, historical groundwater data were evaluated using Sen's Slope trend analyses to determine if significant increasing or decreasing trends were evident. Trend analyses,performed by ® Herst&Associates, are presented in Appendix D and summarized below. DA2003_021WC_Stdce Geologic Associates