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Tabulated Data <br /> 4 . During the May 1991 groundwater sampling round it out of 89 <br /> wells that could be sampled had detectable concentrations of <br /> pesticides. Seven of these 11 exceed the proposed EPA AL. <br /> Pesticides were detected in nine wells that had previously <br /> not been selected for pesticides analysis. One well, LM-27A <br /> detected pesticides that were previously not detected. <br /> The data indicates that organochlorine pesticides are more <br /> widespread throughout DDRW-Tracy than previously thought <br /> based on past analyses. It is apparent that a more detailed <br /> investigation is necessary to fully characterize the <br /> magnitude of pesticide contamination at DDRW-Tracy. <br /> • DDRW-Tracy should provide for a more thorough <br /> investigation of organochlorine pesticides per EPA <br /> comments on the SWMU report and the data presented in <br /> the Quarterly GW Monitoring Program. <br /> • Existing monitoring parameters should change to address <br /> the need for organochlorine pesticides data. <br /> Historical Analytical Results <br /> 5. The historical analytical results for purgeable halocarbons, <br /> found in Appendix D, places "NA" (not analyzed) as the <br /> detection limit for various compounds on several wells. <br /> Some of these wells had detectable quantities for a <br /> particular analyte. As an example, LM-30 detected 12 µg/Y <br /> of 1, 2-dichloroethane, yet the detection limit is shown as <br /> "NA. " <br /> • Please explain how an analyte can be detected, in some <br /> instances above the DHS MCL, if it was not analyzed <br /> for. <br /> Reporting Format <br /> 6. Future submissions of data should be presented in a tabular <br /> format similar to Table 2-5, Summary of Analytical Results. <br /> All compounds analyzed for should be shown along with their <br /> detected value and detection limit. This would include all <br /> of the organic compounds, metals, etc. A column header of <br /> "Other Compounds" which is used in Table 2-5 would not be <br /> acceptable. This revised formatting allows for easy <br /> reference and review without having to search through <br /> voluminous laboratory submissions. It will also facilitate <br /> correlations and provide the ability to recognize trends in <br /> contaminant concentrations. <br /> 3 <br />