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3.1.5 Corrective Action Program
<br /> Field and laboratory results for CAP wells for the fourth quarter 2009 monitoring period
<br /> are summarized in Table 3-2. As shown in Table 3-2, 18 VOCs were detected in CAP
<br /> wells during the current monitoring period. Well AMW-I had the greatest number of
<br /> VOCs (11), including five 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 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.
<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 /> AMW-3 None Apparent None Apparent
<br /> AMW-4 Nitrate-N Barium,Bicarbonate,Calcium,Chloride,
<br /> Magnesium,Potassium,Sodium,Strontium,
<br /> Specific Conductance,TDS,cis-1,2-DCE,
<br /> PCE,TCE,Vinyl Chloride
<br /> AMW-5/5R Barium,Bicarbonate,Chloride, None Apparent
<br /> Nitrate-N,Sodium,Specific
<br /> Conductance,Sulfate,TDS
<br /> AMW-10 Sulfate,cis-1,2-DCE Bicarbonate,Calcium,Chloride,
<br /> Magnesium,Nitrate-N,Potassium, Sodium,
<br /> Strontium, 1,1-DCA,DCDFM,PCE
<br /> AMW-I I None Apparent Calcium,Chloride,Magnesium,Potassium,
<br /> Specific Conductance,TDS,cis-1,2-DCE,
<br /> DCDFM,PCE,TCE
<br /> AMW-18 Bicarbonate,Strontium Chloride,Nitrate-N,pH, Sulfate, Sodium_
<br /> AMW-19 PCE,TCE Chloride,Chromium-Hexavalent,pH,
<br /> I Sodium, Sulfate
<br /> AMW-19BR I 1,1-DCA,cis-1,2-DCE,TCE Chloroform,Nitrate-N, Sulfate
<br /> As shown in this table, significant increasing trends were calculated for one or more
<br /> VOC constituents in CAP wells AMW-1, AMW-1 0, AMW-1 9, and AMW-1 9BR, while
<br /> decreasing VOC trends were noted in CAP wells AMW-I, AMW-4, AMW-10, and
<br /> AMW-11. It should be noted that the increasing concentrations of cis-1,2-DCE trends in
<br /> wells AMW-1, AMW-10, and AMW-I 9BR suggest that natural degradation of VOCs is
<br /> occurring in the vicinity of these wells through reductive dechlorinization.
<br /> DA2009 001"A-4QO9.doc GeoLogic Associates
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