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discussed below either do not show significant trends (rising or falling) or have too few
<br /> data points to establish meaningful trends.
<br /> Well Number Increasing Trends Decreasing Trends
<br /> AMW-2 Bicarbonate,Nitrate-N,Specific None Apparent
<br /> Conductance
<br /> AMW-6 Barium,Chloride, Magnesium,Nitrate-N, None Apparent
<br /> Specific Conductance, Strontium,TDS
<br /> AMW-7 Bicarbonate,Calcium, Chloride, Hexavalent Chromium, Potassium
<br /> Magnesium,Nitrate-N, Specific
<br /> Conductance,Sulfate,TDS
<br /> AMW-12 None Apparent Calcium,Chloride,Magnesium,Strontium
<br /> AMW-13 Bicarbonate, Sulfate Nitrate-N,TCFM
<br /> AMW-14 Barium,Calcium,Chloride,Hexavalent 1,1-DCA, cis-1,2-DCE,DCDFM,PCE,
<br /> Chromium,Magnesium,Nitrate-N, TCE
<br /> Potassium,Sodium, Strontium, Sulfate
<br /> Notes: l,l-DCA—1,1-dichlorethane cis-1,2-DCE—cis-l,2-dichloroethene 1,3-DCB—1,3-dichlobenzene
<br /> With the exception of barium and chloride concentrations measured in well AMW-14, no
<br /> constituent that exhibited a statistically significant increasing trend during the second
<br /> quarter 2012 monitoring event also exceeded their concentration limits. It should be
<br /> noted, however, that the barium and chloride concentrations measured in the sample
<br /> collected from well AMW-14 (0.280 mg/L and 95 mg/L, respectively) are within the
<br /> historical range of values observed at this well. No increasing trends were noted for
<br /> VOC constituents in the DMP wells. However, one or more decreasing trends were
<br /> noted for VOCs in wells AMW-13 and AMW-14.
<br /> 3.1.5 Corrective Action Program
<br /> Field and laboratory results for CAP wells for the second quarter 2012 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-1 had the greatest number of
<br /> VOCs with seven measured above their PQLs. Of note, the elevated acetone and methyl
<br /> ethyl ketone concentrations measured in well AMW-4 are believed to be the result of
<br /> PVC glue that was used by Del-Tech to extend the PVC casing prior to sampling this
<br /> well.
<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. For constituents
<br /> whose historical data consists primarily of non-detects (carbonate alkalinity, oil and
<br /> grease, volatile petroleum hydrocarbons, and VOCs), trend evaluations were performed
<br /> on data from the earliest detection through the present. The observed groundwater
<br /> quality constituent trends were evaluated using Mann-Kendall / Sen's Slope trend
<br /> analyses to determine if significant increasing or decreasing trends were evident in the
<br /> 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.
<br /> C:UO12-0025\FA 2Qr2.doc 10 Geo-Logic Associates
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