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® Well Increasing Trends Decreasing Trends
<br /> Number
<br /> AMW-5/5R Barium,Bicarbonate,Chloride,Nitrate-N, None Apparent
<br /> Sodium,Specific Conductance,Sulfate,
<br /> TDS
<br /> AMW-10 Sulfate,cis-1,2-DCE Calcium,Magnesium,Nitrate-N,
<br /> Potassium,Strontium, 1,1-DCA,DCDFM
<br /> AMW-11 None Apparent Calcium,Chloride,Magnesium,
<br /> Strontium,Specific Conductance TDS,
<br /> cis-1,2-DCE,DCDFM,PCE,TCE
<br /> AMW-18 Bicarbonate Carbonate,Chloride,Nitrate-N,
<br /> Potassium,Sulfate,Sodium
<br /> AMW-19 PCE,TCE Sodium,Sulfate
<br /> The increasing trend exhibited by vinyl chloride and/or cis-1,2-DCE suggests reductive
<br /> dechlorination is occurring in the vicinity of wells AMW-1 and AMW-10.
<br /> 3.1.6 Domestic Well Monitoring
<br /> Two domestic wells(7898-A and 8106-A)were sampled on August 11,2008. Table 3-3
<br /> summarizes the current analytical results for the domestic well samples collected. As
<br /> shown on Table 3-3,three VOCs (DCDFM, PCE, and TCE)were measured above the
<br /> PQL in the samples collected from domestic wells 7898-A and 8106-A. In addition, two
<br /> trace-level VOCs (1,1-DCA and cis-1,2-DCE) were also detected in the sample collected
<br /> from domestic well 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 August 11, 2008. Table 3-4 summarizes the current analytical results for
<br /> surface water samples collected at the Austin Unit and compares the results with the
<br /> WQPS (concentration limits). CLs were exceeded at downgradient surface-water
<br /> monitoring station ASW-2 for bicarbonate, calcium, chloride,magnesium,potassium,
<br /> sodium, sulfate, and TDS. Toluene was detected above the PQL at upstream surface
<br /> water station ASW-1. However, no VOCs were detected at downstream surface water
<br /> monitoring station ASW-2 during the third quarter 2008 monitoring period. Historical
<br /> data from the surface water monitoring points were evaluated for Herst & Associates also
<br /> performed temporal trend analysis using Sen's Slope trend analysis and are presented in
<br /> Appendix D. During the monitoring period,no constituents exhibited a statistically
<br /> significant increasing trend.
<br /> 3.1.8 Constituents of Concern
<br /> During the second quarter 2008 monitoring event, samples were analyzed for the full
<br /> suite of COCs stipulated in RWQCB Order No. R5-2003-0049. The results of the COC
<br /> round indicated that dicamba(a chlorinated herbicide)was detected above the PQL in the
<br /> sample collected from AMW-4, and sulfide was detected above the PQL in the sample
<br /> collected from well AMW-2. Confirmation samples were collected during the
<br /> D:\2008_0010Tk_3WLdec
<br /> 13 Geologic Associates
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