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The greatest number of VOCs, including five measured above the PQL,were detected in
<br /> the sample from well AMW-1.
<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 Sen's Slope trend analyses
<br /> to determine if significant increasing or decreasing trends were evident in the data. Trend
<br /> analyses,performed by Herst& Associates, are presented in Appendix D and are
<br /> 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. As shown in the following table, significant increasing trends were calculated for
<br /> one or more VOC constituents in CAP wells AMW-1 and AMW-19, while decreasing
<br /> trends were noted in CAP wells AMW-10 and AMW-11.
<br /> Well Increasing Trends Decreasing Trends
<br /> Number
<br /> AMW-1 Barium,Bicarbonate,Specific Nitrate-N,pH,Sulfate
<br /> Conductance, 1,1-DCA,cis-1,2-DCE
<br /> AMW-3 None Apparent None Apparent
<br /> AMW4 None Apparent Chloride,Barium,Bicarbonate,Calcium,
<br /> Magnesium, Potassium,Strontium,TDS
<br /> AMW-5/5R Barium,Bicarbonate,Chloride,Nitrate-N, None Apparent
<br /> H,S ecific Conductance,Sulfate,TDS
<br /> AMW-10 Sulfate Calcium,Magnesium,Nitrate-N,
<br /> Potassium, Strontium, 1,1-DCA,DCDFM
<br /> AMW-11 Sodium Calcium,Chloride,Magnesium,
<br /> Strontium,Specific Conductance TDS,
<br /> cis-1,2-DCE,DCDFM,PCE,TCE
<br /> AMW-18 Barium,Bicarbonate Arsenic,Carbonate, Chloride,Nitrate-N,
<br /> Sulfate,Sodium
<br /> AMW-19 PCE Sodium,Sulfate
<br /> The increasing trend exhibited by cis-1,2-DCE suggests reductive dechlorination is
<br /> occurring in the vicinity of wells AMW-1. As summarized in the Annual Corrective
<br /> Action Evaluation prepared by Herst&Associates (2007), the overall groundwater
<br /> quality at the site is generally improving.
<br /> 3.1.6 Domestic Well Monitoring
<br /> Two domestic wells (7898-A and 8106-A)were sampled on February 4, 2008. Table 3-3
<br /> summarizes the current analytical results for the domestic well samples collected. As
<br /> shown on Table 3-3, excluding suspected field/laboratory contaminants,three VOCs
<br /> were measured, all above the PQL, in the sample collected from domestic well 7898-A.
<br /> Five VOCs were detected in the sample collected from domestic well 8106-A, with three
<br /> VOCs measured above the PQL.
<br /> D:\2007-0043\FA_1Q08.doc
<br /> 11 Geologic Associates
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