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3.1.5 Corrective Action Program
<br /> Field and laboratory results for CAP wells for the second quarter 2010 monitoring period
<br /> are summarized in Table 3-2. As shown in Table 3-2, 15 VOCs were detected in CAP
<br /> wells during the current monitoring period. Well AMW-1 had the greatest number of
<br /> VOCs (12), including six measured above the PQL.
<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 Nitrate-N,pH,Sulfate,DCDFM
<br /> Conductance, 1,1-DCA,
<br /> cis-1,2-DCE,Vinyl Chloride
<br /> AMW-3 None Apparent None Apparent
<br /> AMW4 Nitrate-N Barium,Bicarbonate,Calcium,Chloride,
<br /> Magnesium,Potassium,Sodium,Specific
<br /> Conductance,Strontium,TDS,cis-1,2-DCE,
<br /> PCE,TCE,Vinyl Chloride
<br /> AMW-5/5R Barium,Bicarbonate,Chloride, Arsenic
<br /> Nitrate-N,pH,Sodium, Specific
<br /> Conductance, Sulfate,TDS
<br /> AMW-10 Sulfate,cis-1,2-DCE Barium,Bicarbonate,Calcium,Chloride,
<br /> Magnesium,Nitrate-N,Potassium, Sodium,
<br /> Strontium,TDS, 1,1-DCA,DCDFM,PCE,TCE
<br /> AMW-11 None Apparent Calcium,Chloride,Magnesium,Potassium,
<br /> Specific Conductance,TDS, 1,1-DCA,
<br /> cis-1,2-DCE,DCDFM,PCE,TCE
<br /> AMW-18 Bicarbonate,Strontium Chloride,Nitrate-N,pH,Potassium,Sodium,
<br /> Sulfate
<br /> AMW-19 PCE,TCE Hexavalent Chromium,Nitrate-N,pH, Sodium,
<br /> Sulfate,TDS
<br /> AMW-19BR None Apparent Hexavalent Chromium,Nitrate-N,Potassium,
<br /> Sulfate
<br /> As shown in the table above, significant increasing trends were calculated for one or
<br /> more VOC constituents in CAP wells AMW-1, AMW-10, and AMW-19,while one or
<br /> more decreasing VOC trends were noted in CAP wells AMW-1, AMW-4, AMW-10, and
<br /> AMW-11. The increasing trends exhibited for vinyl chloride and/or cis-1,2-DCE at wells
<br /> AMW-1 and AMW-10 suggests reductive dechlorination is occurring in the vicinity of
<br /> these wells.
<br /> D:U010_0013XFA_2Q10.doc
<br /> 11 Geologic Associates
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