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Draft Final ROD Memorandum -5- 22 December 1992 <br /> DDRW, Sharpe <br /> concentration contour maps of these other pervasive VOCs during the remedial <br /> action as graphic aids to the verification of the remedial action. <br /> Use of Old Data <br /> The Draft Final ROD presents the extent of ground water contamination for TCE <br /> (Figures 3, 4, 5 and 6) and Bromacil (Figure 11) based on data that is over two <br /> years old (Second Quarter 1990) . We have previously expressed our concern <br /> regarding the use of out-dated information in our letters dated 16 September 1991 <br /> and 21 May 1992. More current ground water data (Third Quarter 1991) was used for <br /> the 3-D model . More recent ground water monitoring data should have been used to <br /> depict the extent of the contamination because the ROD should reflect the ground <br /> water contamination as currently understood. <br /> Sources of Arsenic and Selenium <br /> The Draft Final ROD states that the sources of arsenic and selenium have not been <br /> positively defined but indicates that the presence of these constituents in ground <br /> water do not appear to be attributable to on-site activities. Conclusive evidence <br /> that Sharpe is not the source of these or other elevated concentrations of <br /> constituents in ground water should be provided as part of the site-wide RI where <br /> each waste management unit should be investigated to determine if soil and ground <br /> water contamination has occurred. <br /> CKW:cw <br />