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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. 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 AMW-
<br /> 1913R, while one or more decreasing VOC trends were noted in CAP wells AMW-1,
<br /> AMW-10, and AMW-1 1.
<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 /> TCE,Vinyl Chloride
<br /> AMW-3 None Apparent None Apparent
<br /> AMW-4 None Apparent None Apparent
<br /> AM)AT-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 Barium,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, 1,1-DCA,
<br /> cis-1,2-DCE,DCDFM,PCE,TCE
<br /> AMW-18 Bicarbonate,Strontium Chloride,Nitrate-N,pH,Potassium, Sulfate,
<br /> Sodium,TDS
<br /> AMW-19 PCE,TCE Chloride,Hexavalent Chromium,pH,
<br /> Sodium, Sulfate,TDS
<br /> AMW-19BR 1,1-DCA Nitrate-N,Potassium,Sulfate
<br /> The increasing trends exhibited for vinyl chloride and/or cis-1,2-DCE suggests reductive
<br /> dechlorination is occurring in the vicinity of wells AMW-I and AMW-10.
<br /> 3.1.6 Domestic WeH Monitoring
<br /> Two domestic wells(7898-A and 8106-A)were sampled on March 31, 2010. Table 3-3
<br /> summarizes the current analytical results for the domestic well samples collected. As
<br /> shown on Table 3-3, two trace-level VOCs (1,1-DCA and cis-1,2-DCE) were detected in
<br /> the sample collected from domestic well 8106-A; one trace level VOC (1,1-DCA) was
<br /> detected in the sample collected from well 7898-A; and three VOCs (DCDFM, PCE, and
<br /> TCE)were measured above the PQL in the samples collected from both domestic wells
<br /> 7898-A and 8106-A.
<br /> 3.1.7 Surface Water Monitoring
<br /> Surface-water sampling was conducted at surface-water monitoring stations ASW-1 and
<br /> ASW-2 on March 31, 2010. Table 3-5 summarizes the current analytical results for
<br /> D:\2010_0013\FA_1Qi0.doc 12 Geologic Associates
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