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EPA Comments on the <br /> DD-Tracy <br /> "Well Monitoring Program <br /> Quarterly Monitoring Report <br /> Fourth Quarter 2000 Sampling Round" <br /> dated February, 2001 <br /> GENERAL COMMENTS <br /> 1, The Well Monitoring Program Quarterly Monitoring Report, Fourth Quarter <br /> 2000 Sampling Round (Report)presents quarterly groundwater sampling data, <br /> but the report provides no plume maps showing chemical concentrations nor is <br /> an evaluation of the data performed. Without evaluation and interpretation,the <br /> data provided in the Report are not useful for purposes of evaluating the <br /> success of the remedy as stated in Section 9.1 of the Record of Decision <br /> (Monitoring Program). Please revise the Report to include chemical <br /> concentration maps for TCE and PCE, at a minimum, and to provide a brief <br /> evaluation regarding plume migration, the change in chemical concentrations <br /> since the extraction and treatment system began, and identification of new <br /> plumes, if relevant. In addition, please provide an evaluation of the anomalous <br /> concentration measurements and how these measurements impact data <br /> usability and the current understanding of plume migration. <br /> 2. As shown in Table 3-1 (page 3-2), four extraction wells were not sampled <br /> because the pumps were not operating,but an explanation for the operational <br /> problems was not provided. This comment has been raised in connection with <br /> previous Quarterly Monitoring Reports, and in its Response to Comments on <br /> the First Quarter 2000 Quarterly Monitoring Report,the Army agreed to <br /> present this information starting with this Fourth Quarter 2000 report. <br /> However, pump failure appears to be a continuing problem and non- <br /> operational extraction wells are not being sampled. Due to these conditions, <br /> the remedy may not be fully operational or adequately monitored. To better <br /> evaluate the remedy for the Site,please include a section in the Report that <br /> discusses extraction system improvements and provides a treatment system <br /> effectiveness evaluation. Please include an evaluation of how the pump failure <br /> affects the treatment system capture zones and contaminant migration and state <br /> how problems with the system, such as pump failures, will be corrected. <br /> 1 <br />