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change in the site's natural geochemistry near AMW-14 in 2010. This change was signified by a shift in chloride at AMW-14 to higher but stable concentrations. The second quarter 2012 field temperature value at AMW-6 (23.5 °C) is within the range of values observed at that well since the beginning of monitoring in May 1995 (16.7 to 24 °C). As discussed above,temperature at AMW-6 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-6 (a= 0.05) indicates that the temperature data at AMW-6 are statistically distinct from those at the upgradient well. The Wilcoxon rank sum plot is presented in Appendix E. The presence of stable temperature values at AMW-6 that are statistically distinct from upgradient temperature values indicates that the exceedance for temperature at AMW-6 in the second quarter 2012 is likely due to spatial variation in the natural groundwater temperatures at the site. The second quarter 2012 concentration of dichlorodifluoromethane at AMW-13 (0.51 ug/L) is within the range of concentrations observed that well since the beginning of monitoring in April 1995 (<0.18 to 130 ug/L). As discussed above, dichlorodifluoromethane at AMW-13 does not exhibit a significant increasing statistical trend. The second quarter 2012 concentration of tetrachloroethane at AMW-13 (8.5 ug/L) is within the range of concentrations observed at that well since the beginning of monitoring in October 1991 (<0.21 to 43 ug/L), but is above the National Primary Drinking Water Standard of 5 ug/L. However, as discussed above, tetrachloroethane at AMW-13 does not exhibit a significant increasing statistical trend. The second quarter 2012 concentration of trichloroethene at AMW-13 (2.2 ug/L) is within the range of concentrations observed at that well since the beginning of monitoring October 1991 (0.17 to 15 ug/L), and is below the National Primary Drinking Water Standard of 5 ug/L. As discussed above,trichloroethene at AMW-13 does not exhibit a significant increasing statistical trend. The second quarter 2012 concentration of tetrachloroethene at AMW-14 (1.2 ug/L) is within the range of concentrations observed at that well since the beginning of monitoring July 1995 (<0.21 to 100 ug/L), and is below the National Primary Drinking Water Standard of 5 ug/L. As discussed above,tetrachloroethene at AMW-14 does not exhibit a significant increasing statistical trend. 2.2 Corrective Action Monitoring During the second quarter 2012 monitoring event, Del-Tech collected groundwater samples from corrective action monitoring wells (AMW-1, AMW-4, AMW-5R, AMW-10, AMW-11, AMW- 18, AMW-19, and AMW-19BR). Corrective action monitoring well AMW-5R is a replacement for corrective action monitoring well AMW-5. Corrective action monitoring well AMW-19BR is a replacement for corrective action monitoring well AMW-19B. The field results provided by Del-Tech and laboratory results provided by BC Labs for the second quarter 2012 corrective action monitoring event are summarized on Table 2.3. The historical groundwater data for the corrective action monitoring wells are presented in Appendix F. Times series concentration plots of historical groundwater data for the detection monitoring wells are presented in Appendix G. For VOCs, only those compounds that exhibited detections at corrective action monitoring wells during the second quarter 2012 monitoring event were plotted. During the second quarter 2012, there were no VOCs detected above the laboratory RL in wells AMW4, AMW-5R, AMW-11, AMW-18, or AMW-19. 1,1-Dichloroethane, 1,4- dichlorobenzene, benzene, chlorobenzene, cis-1,2-dichlorobenzene, tetracholorethene, trichloroethene, and vinyl chloride were detected at AMW-1 above the laboratory RL. 4