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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, AMW-10, AMW-19, and
<br /> AMW-1913R, while decreasing VOC trends were noted in CAP wells AMW-1,AMW-4,
<br /> AMW-10, and AMW-11.
<br /> Well Increasing Trends Decreasing Trends
<br /> Number
<br /> AMW-1 Barium,Bicarbonate, Specific Nitrate-N,pH,Sulfate,DCDFM
<br /> Conductance, 1,1-DCA,cis-1,2-DCE,
<br /> Vinyl Chloride
<br /> AMW-3 None Apparent None Apparent
<br /> AMW4 Nitrate-N, Sulfate Barium,Bicarbonate,Calcium,Chloride,
<br /> Magnesium,Potassium,Sodium,Strontium,
<br /> Specific Conductance,TDS, 1,1-DCA,
<br /> 1,4-Dichlorobenzene,Benzene,DCDFM,
<br /> cls-1,2-DCE,PCE,TCE,trans-1,2-
<br /> dichloroethene,Vinyl Chloride
<br /> AMW-5/5R Barium,Bicarbonate,Chloride, None Apparent
<br /> Nitrate-N,pH,Sodium,Specific
<br /> Conductance,Sulfate,TDS
<br /> AMW-10 Sulfate,cis-1,2-DCE Calcium,Chloride,Magnesium,Nitrate-N,
<br /> Potassium, Sodium, Strontium, 1,1-DCA,
<br /> DCDFM,PCE
<br /> AMW-11 None Apparent Calcium,Chloride,Magnesium,Potassium,
<br /> Strontium, Specific Conductance,TDS, 1,1-
<br /> DCA,cis-1,2-DCE,DCDFM,PCE,TCE
<br /> AMW-18 Bicarbonate, Strontium Carbonate,Chloride,Nitrate-N,pH,
<br /> Potassium, Sulfate,Sodium
<br /> AMW-19 PCE,TCE pH,Sodium, Sulfate
<br /> AMW-19BR Barium,pH, 1,1-DCA,cis-1,2-DCE, Sulfate
<br /> TCE
<br /> The increasing vinyl chloride and/or cis-1,2-DCE trends in wells AMW-1 and AMW-10
<br /> suggest that natural degradation of VOCs is occurring in the vicinity of these wells
<br /> through reductive dechlorinization.
<br /> 3.1.6 Domestic Well Monitoring
<br /> Two domestic wells (7898-A and 8106-A)were sampled on August 10, 2009. Table 3-3
<br /> summarizes the current analytical results for the domestic well samples collected. As
<br /> shown on Table 3-3, three VOCs (DCDFM, PCE, and TCE)were measured above the
<br /> PQL in the samples collected from both domestic wells 7898-A and 8106-A.
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<br /> 11 Geologic Associates
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