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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 2010 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 l) <br /> Barium 1 0.2284 0.263 0.263 <br /> Chloride 77.69 81.4 <br /> Hexavalent Chromium 0.005 0.0068' 0.0068' 81.4 <br /> Oil and Grease 2.55 3.3' <br /> VOLATILE ORGANIC COMPOUNDS ) <br /> etrachloroethene 1.0 5.0 1.8 <br /> Trichloroethene 1.0 1.4 <br /> NOTES: (a)-Background Well. <br /> j -Trace Value <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 Mann-Kendall/ Sen's Slope trend analyses to determine if 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 below either do not show significant trends (rising or falling) or <br /> have too few data points to establish meaningful trends. <br /> Well Number Increasing Trends Decreasing Trends <br /> AMW-2 Bicarbonate,Nitrate-N,Specific pH <br /> Conductance <br /> AMW-6 Barium,Bicarbonate,Chloride,Nitrate-N, None Apparent <br /> Magnesium, Strontium,TDS <br /> AMW-7 Bicarbonate,Calcium,Chloride, Potassium <br /> Magnesium,Nitrate-N, Specific <br /> Conductance, Sulfate,TDS <br /> AMW-12 None Apparent Barium,Calcium,Chloride,Magnesium, <br /> Potassium,Strontium <br /> AMW-13 Bicarbonate Nitrate-N <br /> AMW-14 Barium,Calcium,Hexavalent Chromium, None Apparent <br /> Magnesium,Nitrate-N,Potassium, <br /> Sodium,Strontium <br /> With the exception of barium concentrations measured in well AMW-14, no constituents <br /> that exhibited a statistically significant increasing trend during the third quarter 2010 <br /> monitoring event and also exceeded their concentration limits. The third quarter barium <br /> concentration measured in the sample collected from well AMW-14 (0.263 mg/L)is <br /> D:120 t0_00 I 3\FA_3Q t 0.doc <br /> 10 <br />