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3.1.5 Corrective Action Program
<br /> Field and laboratory results for CAP wells for the fourth quarter 2011 monitoring period
<br /> are summarized in Table 3-2. As shown in Table 3)-2, 14 VOCs were detected in CAP
<br /> wells during the current monitoring period. Well AMW-I had the greatest number of
<br /> VOCs with six measured above their PQLs.
<br /> In order to evaluate the effectiveness of corrective action measures, particularly with the
<br /> groundwater treatment facility(GTF), trend analyses were performed for CAP wells at
<br /> the Austin Unit, beginning in 1994 when the GTF began operation. The observed
<br /> groundwater quality constituent trends were evaluated using Mann-Kendall/ Sen's Slope
<br /> trend analyses to determine if significant increasing or decreasing trends were evident in
<br /> the data. Trend analyses, performed by Herst&Associates, are presented in Appendix D
<br /> and are summarized below. Wells and analytes not discussed below either do not show
<br /> significant trends (rising or falling) or have too few data points to establish meaningful
<br /> trends.
<br /> Well Increasing Trends Decreasing Trends
<br /> Number
<br /> AMW-1 Barium, Bicarbonate, Specific Chloride,Nitrate-N,pH, Sulfate,DCDFM,
<br /> Conductance, 1,1-DCA, 1,2-Dichlorobenzene, I,')-Dichlorobenzene
<br /> Chlorobenzene,cis-1,2-DCE
<br /> AMW-3 None Apparent None Apparent
<br /> AMW-4 pH,Nitrate-N Barium, Bicarbonate,Calcium,Chloride,
<br /> Magnesium, Potassium,Specific Conductance,
<br /> Strontium,TDS, 1,1-DCA, 1,4-Dichlorobenzene,
<br /> Benzene,cis-1,2-DCE, DCDFM, PCE,TCE,
<br /> trans-1,2-Dichloroethene
<br /> AMW-5R Bicarbonate,Chloride,Nitrate-N, PCE
<br /> pH, Potassium,Specific
<br /> Conductance, Sulfate,TDS
<br /> AMW-10 Sulfate,cis-1,2-DCE Barium,Bicarbonate,Calcium,Chloride, Specific
<br /> Conductance, Magnesium,Nitrate-N, Potassium,
<br /> Sodium, Strontium, TDS, 1,1-DCA,DCDFM,
<br /> PCE,TCE
<br /> AMW-I I pH Barium,Chloride,Magnesium, Potassium,
<br /> Specific Conductance,TDS, 1,1-DCA,
<br /> cis-1,2-DCE, DCDFM,PCE,TCE
<br /> AMW-18 Bicarbonate Carbonate,Chloride,Nitrate-N, Potassium,
<br /> Sodium,Sulfate,TDS
<br /> AMW-19 Barium, PCE Hexavalent Chromium,Nitrate-N, Sodium, Sulfate
<br /> AMW-19BR pH Hexavalent Chromium,Nitrate-N,Potassium,
<br /> Sodium, Sulfate
<br /> As shown in the table above, significant increasing trends were calculated for three VOC
<br /> constituents in CAP well AMW-1, and for one VOC in wells AMW-10 and AMW-19.
<br /> Decreasing VOC trends were noted in CAP wells AMW-I, AMW-4, AMW-5R,
<br /> AMW-10, and AMW-11. The increasing trend exhibited for cis-1,2-DCE at wells
<br /> AMW-I and AMW-10, suggests reductive dechlorination is occurring in the vicinity of
<br /> these wells.
<br /> C:\zou-ooso\Fa_oQn.aoc 11 eo-Logic Associates
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