ARCHIVED REPORTS_2012_2 - Laserfiche WebLink

Home Browse Search

statistically distinct. The Wilcoxon rank sum plot is presented in Appendix E. This indicates that the significant increasing statistical trend in barium at W-14 may be due to a localized change in the site's natural geochemistry near AMW-14 in 2009. This change was signified by a shift in barium at AMW-14 to higher but stable concentrations. The third quarter 2012 chloride concentration at AMW-12 (88 mg/L) is within the range of concentrations observed at that well since the beginning of monitoring in July 1995 (24 to 98 mg/L). As discussed above, chloride at AMW-12 does not exhibit a significant increasing statistical trend. A Wilcoxon rank -sum test comparing the chloride data at upgradient well AMW-2 to the data at AMW-12 (a = 0.05) indicates that the chloride data at AMW-12 are not statistically distinct from those at the upgradient well. The Wilcoxon rank sum plot is presented in Appendix E. The presence of stable chloride concentrations at AMW-12 that are not statistically distinct from upgradient concentrations indicates that the concentration limit exceedance for chloride at AMW-12 in the third quarter 2012 is likely due to a very recent variation in the natural groundwater geochemistry near AMW-12. This exceedance will be confirmed during the next monitoring event in the fourth quarter 2012. The third quarter 2012 chloride concentration at AMW-14 (100 mg/L) is within the range of concentrations observed at that well since the beginning of monitoring in July 1995 (3 to 168 mg/L). As discussed above, chloride at AMW-14 exhibits a significant increasing statistical trend. The increasing trend is not observed when the data are limited to the period of March 2011 to August 2012. A Wilcoxon rank -sum test comparing the July 1995 to November 2010 chloride data at AMW-14 to the March 2011 to August 2012 data data (a = 0.05) indicates that these periods are statistically distinct. The Wilcoxon rank sum plot is presented in Appendix E. This indicates that the significant increasing statistical trend in chloride at AMW-14 may be due to a ID localized change in the site's natural geochemistry near AMW-14 in 2010-2011. This change was signified by a shift in chloride at AMW-14 to higher but stable concentrations. The third quarter 2012 hexavalent chromium concentration at AMW-7 (0.0049 mg/L) is within the range of concentrations observed at that well since the beginning of monitoring in July 1995 (<0.002 to 0.01 mg/L). As discussed above, hexavalent chromium at AMW-7 does not exhibit a significant increasing statistical trend. A Wilcoxon rank -sum test comparing the hexavalent chromium data at upgradient well AMW-2 to the data at AMW-7 (a = 0.05) indicates that the hexavalent chromium data at AMW-7 are statistically distinct from those at the upgradient well. The Wilcoxon rank sum plot is presented in Appendix E. The presence of stable hexavalent chromium concentrations at AMW-7 that are statistically distinct from upgradient concentrations indicates that the concentration limit exceedance for hexavalent chromium at AMW-7 in the third quarter 2012 is likely due to spatial variation in the natural groundwater geochemistry at the site. The third quarter 2012 field temperature value at AMW-7 (22.9 °C) is within the range of values observed at that well since the beginning of monitoring in March 1994 (16.9 to 24 °C). As discussed above, temperature at AMW-7 does not exhibit a significant increasing statistical trend. A Wilcoxon rank -sum test comparing the temperature data at upgradient well AMW-2 to the data at AMW-7 (a = 0.05) indicates that the temperature data at AMW-7 are statistically distinct from those at the upgradient well. The Wilcoxon rank sum plot is presented in Appendix E. The presence of stable temperatures at AMW-7 that are statistically distinct from upgradient temperatures indicates that the exceedance for temperature at AMW-7 in the third quarter 2012 is likely due to spatial variation in the natural groundwater temperatures at the site. The third quarter 2012 field temperature value at AMW-14 (21.8 °C) is within the range of values observed at that well since the beginning of monitoring in November 1995 (15.7 to 23 °C). As