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CONSTITUENT Concentration DMP MONITORING WELL <br /> LimitI AMW-6 AMW-7 AMW-12 AMW-13 AMW-14 <br /> MONITORING PARAMETERS m <br /> Barium 1 0.2265 1 1 0.250 1 0.228 <br /> Hexavalent Chromium 1 0.004865 1 1 0.0054' 1 0.0081' 1 1 0.0081' <br /> OLATILE ORGANIC COMPOUNDS <br /> etrachloroethene 1.0 9.7 2.4 <br /> richloroethene 1.0 2.2 <br /> NOTES: 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 None Apparent <br /> Conductance <br /> AMW-6 Barium,Chloride,Nitrate-N,Specific None Apparent <br /> Conductance, 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 /> Strontium <br /> AMW-13 Bicarbonate Nitrate-N <br /> AMW-14 Barium,Calcium,Hexavalent Chromium, PCE,TCE <br /> Magnesium,Nitrate-N,Potassium, <br /> Sodium,Strontium,Sulfate <br /> With the exception of barium concentrations measured in well AMW-14, no constituents <br /> that exhibited a statistically significant increasing trend during the first quarter 2011 <br /> monitoring event and also exceeded their concentration limits. The first quarter 2011 <br /> barium concentration measured in the sample collected from well AMW-14 (0.228 mg/L) <br /> is within the historical range of values observed at this well, and is well below the state <br /> primary drinking water standard (1 mg/L). <br /> 3.1.5 Corrective Action Program <br /> Field and laboratory results for CAP wells for the first quarter 2011 monitoring period are <br /> summarized in Table 3-2. As shown in Table 3-2, eight VOCs were detected in CAP <br /> wells during the current monitoring period. Well AMW-1 had the greatest number of <br /> VOCs (five), including four measured above the PQL. <br /> D:\2011_0050\1FA_1Q11.docx <br /> 10 Geologic Associates <br />