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Volatile Organic Compounds <br /> As shown in Table 3-1, the following were measured above respective PQLs: <br /> tetrachloroethane (PCE), trichloroethene (TCE), and dichlorodifluoromethane (DCDFM) <br /> in the sample collected from well AMW-13; and PCE in the sample collected from well <br /> AMW-14. In addition, trace concentrations of three VOCs were measured in the sample <br /> from well AMW-13 and a trace concentration of PCE was also measured in the sample <br /> collected from wells AMW-6. <br /> Concentration Limit Comparison <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; the results of the statistical <br /> analyses performed by Herst&Associates are presented in Appendix D. Based on a <br /> comparison of the data obtained during the fourth quarter 2012 monitoring period, the <br /> following analytes were found to exceed a CL. <br /> CONSTITUENT Concentration I DMP MONITORING WELL <br /> Limit AMW-2 AMW-6 AMW-7 AMW-12 AMW-13 AMW-14 <br /> MONITORING PARAMETERS m <br /> Barium 0.2214 0.230 0.260 0.270 <br /> homi74.36 87 8l <br /> Chromium(Hexavalent) 1 0.004896 0.0051 1 0.0058 <br /> VOLATILE ORGANIC COMPOUNDS <br /> Dichlorofluoromethane 1 0.5 1 1 0.50 <br /> etrachloroethene 1 0.5 1 1 7.8 0.86 <br /> Trichloroethene 1 0.5 1 1 2.2 <br /> NOTES: (B)-Background Well. <br /> 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. For constituents whose historical data consists primarily of non- <br /> detects (carbonate alkalinity, oil and grease, volatile petroleum hydrocarbons, and <br /> VOCs), trend evaluations were performed on data from the earliest detection through the <br /> present. The observed groundwater quality constituent trends were evaluated using <br /> Mann-Kendall/ Sen's Slope trend analyses to determine if statistically significant <br /> increasing or decreasing trends were evident in the data. Trend analyses, performed by <br /> Herst& Associates, are presented in Appendix D and summarized below. Wells and <br /> analytes not discussed in the following table either do not show significant trends (rising <br /> or falling) or have too few data points to establish meaningful trends. <br /> C:\zoi2-oo251FA4Q12.doc 10 Geo-Logic Associates <br />