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No Further Action Request Section 3 0 <br /> Former American Forest Products Facility • 2/16/2006 <br /> URS Project No 17322736 Page 3-1 <br /> 30 CONCENTRATION VERSUS TIME TRENDS FOR 1,2-DCA <br /> Time-versus-concentration plots for 1,2-DCA in monitoring wells DMW-2, DMW-5, DMW-6, and <br /> DMW-9 are provided in Figures 3 and 4 The data represent quarterly monitoring results for samples <br /> collected and analyzed beginning in August 2000, when 1,2-DCA became a constituent of concern at the <br /> site A linear regression trend line and equation are shown for the data set for each well The equation of <br /> r the trend line is in the form of y = nix f b, where m is the slope of the line A positive value for m <br /> indicates a rising trend, while a negative value indicates decreasing concentrations of the plotted <br /> constituent <br /> rA downward trend for 1,2-DCA is shown for all wells where several years of record are available While <br /> an upward trend is calculated for monitoring well DMW-9, it should be noted that only eight quarters of <br /> data are available, the results show considerable variability, and when the data are corrected for outliers, <br /> I e ,the highest and lowest results, the concentration trend becomes negative for this well also <br /> The concentration-versus-time trends presented in Figures 3 and 4 demonstrate an overall decreasing <br /> contaminant concentration trend for the 1,2-DCA plume These data support and are consistent with the in <br /> situ sampling-data presented in Section 2 and quarterly groun water monitoring data that show that the <br /> 1,2-DCA plume is stable and demonstrates a decreasing concentration trend, thus meeting one of the <br /> requirements for no further action <br /> r +r <br /> r <br /> r <br /> r <br /> C 1'Pro)ects\UMAFP12005 DCA lnvestigation\11P Investigation Report\AFP 2005 Report WP-TE-Rev02 doc <br />