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Well
<br />Increasing Trends
<br />Decreasing Trends
<br />Number
<br />AMW-1
<br />Barium, Bicarbonate, Specific
<br />Chloride, Nitrate -N, pH, Sulfate,
<br />Conductance, cis-1,2-DCE, Vinyl Chloride
<br />Dichlorodifluoromethane (DCDFM)
<br />AMW-3
<br />Chloride, Nitrate -N, Specific Conductance
<br />Arsenic, Barium, pH
<br />AMW-4
<br />None Apparent
<br />Chloride, Barium, Bicarbonate,
<br />Calcium, Magnesium, Strontium,
<br />DCDFM, Methylene Chloride
<br />AMW-5
<br />Chloride, Nitrate -N, pH, Specific
<br />None Apparent
<br />Conductance, Sulfate, TDS
<br />AMW-10
<br />Barium, Sulfate, Specific Conductance,
<br />None Apparent
<br />cis-1,2-DCE
<br />AMW-11
<br />None Apparent
<br />Calcium, Chloride, Magnesium,
<br />Specific Conductance TDS, cis-1,2-
<br />DCE, DCDFM, PCE, TCE
<br />AMW-18
<br />Barium
<br />Arsenic, Sodium
<br />AMW-19A
<br />None Apparent
<br />Sulfate
<br />The presence of cis-1,2-DCE suggests natural dechlorination is occurring in the vicinity
<br />of wells AMW-1 and AMW-10. As summarized in the Annual Corrective Action
<br />Evaluation prepared by Herst & Associates (2006), the overall groundwater quality at the
<br />site is improving.
<br />3.1.6 Domestic Well Monitoring
<br />Two domestic wells (7898-A and 8106-A) were sampled on November 15, 2005. Table
<br />3-3 summarizes the current analytical results for the domestic well samples collected. As
<br />shown on Table 3-3 and excluding suspected lab contaminants, two VOCs were
<br />measured in the sample from domestic well 7898-A with all three VOCs (PCE and TCE)
<br />measured above the PQL, while five VOCs were measured in the sample from domestic
<br />well 8106-A with three VOCs (DCDFM, PCE, and TCE) measured above the PQL.
<br />3.1.7 Surface Water Monitoring
<br />Surface water samples were collected on November 28, 2006, at surface water
<br />monitoring stations ASW -1 and ASW -2. Table 3-4 summarizes the current analytical
<br />results for surface water samples collected at the Austin Unit and compares the results
<br />with the WQPS (concentration limits). Excluding suspected laboratory contaminants, no
<br />VOCs were detected at the surface water monitoring stations during the fourth quarter
<br />2006 monitoring period. In addition, Herst & Associates calculated CLs and trend
<br />analyses for the surface water monitoring stations (Appendix D). During the fourth
<br />quarter 2006 monitoring period no CLs were exceeded at downgradient surface water
<br />station ASW -2.
<br />3.1.8 Leachate Monitoring
<br />According to the Operations Manager, no leachate was taken off site during the fourth •
<br />quarter 2006. The leachate collection system, which collects leachate from the north face
<br />11):12003_021\ForwardAnstin_fO6.doc\
<br />12 Geologic Associates
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