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® 3.1.4 Detection Monitoring Program <br /> Field and laboratory results for the DMP wells for the third quarter 2008 are summarized <br /> in Table 3-1 and time-series plots are presented in Appendix D. As shown in Table 3-1, <br /> trace concentrations of bromoform and dibromochloromethane were measured in the <br /> sample collected from well AMW-2; trace concentrations of DCDFM and TCE were <br /> measured in the sample collected from well AMW-6; a trace concentration of bromoform <br /> was measured in the sample collected from well AMW-12; and a trace concentration of <br /> TCE was measured in the sample collected from well AMW-13. In addition,bromoform <br /> and dibromochloromethane were measured above the PQL in the sample collected from <br /> well AMW-7; PCE was measured above the PQL in the samples collected from wells <br /> AMW-6 and AMW-13; and DCDFM, PCE, and TCE were measured above the PQL in <br /> the sample collected from well AMW-14. As discussed in Section 3.1.2,bromoform and <br /> dibromochloromethane are suspected laboratory/field contaminants since similar <br /> concentrations were also measured in QA/QC blanks during the current monitoring <br /> period. <br /> For the DMP wells at the Austin Unit, CLs are calculated for the water quality protection <br /> standards (WQPS). The CLs shown in Table 3-1 were calculated by Herst&Associates <br /> using Sanitas®, a state-approved statistical software program. Based on a comparison of <br /> the data obtained during the third quarter 2008 monitoring period,the following analytes <br /> were found to exceed a CL. The results of the statistical analyses performed by Herst <br /> Associates are presented in Appendix D. <br /> CONSTITUENT Concentration DMP MONITORING WELL <br /> Limit AMW-2 AMW-6 AMW-7 AMW-13 AMW-14 <br /> MONITORING PARAMETERS(m ) <br /> Barium 1 0.242 0.26 <br /> Chromium,Hexavalent 1 0.005 0.0055 0.0060 <br /> VOLATILE ORGANIC COMPOUNDS ) <br /> Bromoform 0.5 1.3* 1.1* <br /> Dibromochloromethane 0.5 0.81 <br /> etrachloroethene 0.5 0.96 2.7 15 <br /> Trichloroethene 0.5 1.3 <br /> NOTES: (B)-Background Well. <br /> j—Trace Value(between the MDL and PQL). <br /> *—Suspected Field/Laboratory Contaminant. <br /> DMP-Trend Analyses <br /> In order to evaluate changes in water quality in DMP wells at the Austin Unit, historical <br /> trends in groundwater were evaluated beginning in 1994 when the groundwater treatment <br /> facility began operation. The observed groundwater quality constituent trends were <br /> evaluated using Sen's Slope trend analyses to determine if significant increasing or <br /> decreasing trends were evident in the data. Trend analyses, performed by Herst & <br /> Associates, are presented in Appendix D and summarized below. Wells and analytes not <br /> discussed below either do not show significant trends(rising or falling) or have too few <br /> data points to establish meaningful trends. <br /> D:%2008_0010\FA 3Q08.doc <br /> 11 Geologic Associates <br />