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Concentration Limit Thresholds
<br /> As specified in RWQCB Order No.R5-2003-0049 the routine monitoring parameters
<br /> obtained during the fourth quarter 2013 monitoring period were compared to interwell
<br /> CLs established for the Austin Unit DMP wells. The CLs shown in Table 3-1 were
<br /> calculated using Sanitaso,a state-approved statistical software program. Details
<br /> regarding the concentration limit calculations are discussed in Appendix D. Based on a
<br /> comparison of the data obtained during the fourth quarter 2013 monitoring period,
<br /> inorganic CLs were exceeded for barium in the samples collected from wells AMW-12,
<br /> AMW-13, and AMW-14; and for chloride in wells AMW-12 and AMW-14. For any
<br /> inorganic monitoring parameter that exceeded a CL,Mann-Kendall/Sen's Slope trend
<br /> analyses was performed to determine if statistically significant increasing temporal trends
<br /> were evident in the data. Trend analyses indicate statistically significant increasing
<br /> temporal trends for barium and chloride concentrations in wells AMW-12 and AMW-14.
<br /> Trend analyses calculations are presented in Appendix D.
<br /> Corrective Action Program
<br /> Field and laboratory results for CAP wells for the fourth quarter 2013 monitoring period
<br /> are summarized in Table 3-2A. As shown in Table 3-2A, 13 VOCs were detected in
<br /> routine CAP wells during the current monitoring period. Well AMW-1 had the greatest
<br /> number of VOCs with eight measured above their PQLs.
<br /> Trend Analyses
<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. 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, are presented in Appendix D and are summarized below. Wells
<br /> and analytes not discussed below either do not show significant trends (rising or falling)
<br /> or have too few data points to establish meaningful trends.
<br /> Well Increasing Trends Decreasing Trends
<br /> Number
<br /> AMW-1 Arsenic,Barium, 1,1-DCA, Nitrate,pH,Sodium,Sulfate,DCDFM
<br /> Chlorobenzene,cis-1,2-DCE
<br /> AMW-3 - -
<br /> AMW-4 pH Chloride,Potassium,TDS, 1,1-DCA, 1,4-DCB,
<br /> Benzene,cis-1,2-DCE,DCDFM,PCE,
<br /> trans-1,2-DCE,TCE,Vinyl Chloride
<br /> AMW-5R - Chloride,Nitrate
<br /> AMW-10 Sulfate Barium,Bicarbonate,Calcium,Chloride,
<br /> Hexavalent Chromium,Magnesium,Nitrate,
<br /> Potassium,Sodium,TDS, 1,1-DCA,DCDFM,
<br /> PCE,TCE,Vinyl Chloride
<br /> C:U013.0021TA_4Q13.d" 10 Geo-Logic Associates
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