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i <br /> 6. Figures 4.3-13a,4.4-1,4.4-2,4.5-1a: The figures show trends in chemical <br /> concentrations over the last four sampling events using trend arrows. However, in almost <br /> all cases where an arrow indicates a trend within the data box, there do not appear to be <br /> enough data points to support this trend. For example, in Figure 4.4-2, a decreasing trend <br /> is shown for dieldrin in LM101A and LM003AA although these wells were only sampled <br /> twice during the reporting period. Please expand the footnotes explaining the trend <br /> arrows to reference the trend discussion and tables in section 3.0 so that readers are not <br /> confused by the presence of a trend arrow and what appears to be too little data to support <br /> the trend. <br /> 7. Table 4.1-2, Page 4-15: The table shows that the highest concentrations detected during <br /> the reporting period were detected in the most recent sampling event for dioxins, many of <br /> the metals, and pesticides. Please include an evaluation of these findings in the Report. <br /> In addition, several of the compounds are listed as not having established MCLS. <br /> However, lead does have an established MCL of 15 ug/l. In addition, the MCL for <br /> cadmium listed in the table (0.01 mg/1) is incorrect. The MCL for cadmium is 0.005 <br /> mg/l. For accuracy, please update Table 4.1-2 to include the most current available <br /> MCLS for all listed compounds. This comment also affects Table 4.1-3. <br /> 8. Section 5.3.1.4, Page 5-2: The text states that seven extraction well pumps at Treatment <br /> Plant#2 were replaced at the end of the 3rd quarter 2000, but the wells with replacement <br /> pumps are not identified. Identification of these wells would assist in evaluating the <br /> activities proposed to increase the contaminant capture efficiency of the extraction <br /> system. Please revise the Report to list the seven extraction wells where pumps were <br /> replaced. <br /> 4. Section 5.3.2.5, Page 5-3 and Figure 5.3-2: The text states that the eastern plume is <br /> approximately 73% captured. According to Figure 5.3-2, the portion which is not <br /> captured lies to the northeast of the capture zone limit. No extraction wells are located in <br /> this area, northeast of(downgradient) and beyond the capture zone limit, so it is unclear <br /> how this portion of the plume can be captured. Please revise the Report to explain how <br /> the existing extraction well network will capture the currently-uncaptured portion of the <br /> eastern contaminant plume in the Upper Horizon or how this portion of the plume will be <br /> addressed in the future. <br /> 5 <br />