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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 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 meaningftil
<br /> trends.
<br /> Well Increasing Trends Decreasing Trends
<br /> Number
<br /> AMW-1 Barium,Bicarbonate,Specific Nitrate-N,pH,Sulfate,DCDFM
<br /> Conductance,cis-1,2-DCE,TCE,
<br /> Vinyl Chloride
<br /> AMW-3 None Apparent None Apparent
<br /> AMW-4 Nitrate-N,pH Barium,Bicarbonate,Calcium,Chloride,
<br /> Magnesium,Potassium, Sodium,Specific
<br /> Conductance,Strontium,TDS, 1,4-DCB,Benzene,
<br /> cis-1,2-DCE,DCDFM,GRO,PCE,TCE,
<br /> Vinyl Chloride
<br /> AMW-5/5R Bicarbonate,Chloride,Nitrate-N, None Apparent
<br /> pH,Potassium, 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,DCDFM,PCE,TCE
<br /> AMW-I I pH Barium,Bicarbonate,Calcium,Chloride,
<br /> Magnesium,Potassium,Specific Conductance,
<br /> TDS,cis-1,2-DCE,DCDFM,PCE,TCE
<br /> AMW-18 None Apparent Chloride,Nitrate-N,Potassium,Sodium,Sulfate,
<br /> TDS
<br /> AMW-19 PCE,TCE Nitrate-N,Sodium, Sulfate,TDS
<br /> AMW-I 9BR Arsenic,pH,DCDFM Nitrate-N,Potassium, Sodium
<br /> Notes: 1,4-dichlorobenzene=1,4-DCB cis-1,2-dichloroethene=cis 1,2-DCE
<br /> gasoline range organics=GRO
<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, AMW-19, and AMW-I 913R,
<br /> while one or more decreasing VOC trends were noted in CAP wells AMW-1,AMW-4,
<br /> AMW-10, and AMW-11. The increasing trend exhibited for vinyl chloride and/or cis-
<br /> 1,2-DCE at wells AMW-I and AMW-10, suggests reductive dechlorination is occurring
<br /> in the vicinity of these wells.
<br /> 3.1.6 Domestic Well Monitoring
<br /> Two domestic wells (7898-A and 8106-A)were sampled on February 24, 2011. Table 3-
<br /> 3 summarizes the current analytical results for the domestic well samples collected. In
<br /> the sample collected from well 7898-A, TCE was measured at a trace concentration and
<br /> PCE was measured above the PQL. In the sample collected from well 8106-A,PCE and
<br /> TCE were both measured above their respective PQLs.
<br /> DA201 1_0050\FA-IQ I I.doex 11 Geologic Associates
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