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4. Figure 5.34A Estimated Contaminant Plumes and Extraction Well Capture Zones <br /> for the Upper Hydrologic Zone Third Quarter 2005, DDJC-Tracy, Page 5-41: <br /> Further justification is needed for why the trichloroethene(TCE)plume is not shown <br /> extending past the estimated capture zone for extraction wells EW034AU, EW045AU, <br /> and EW046AU. Figure 5.34A shows the TCE plume within the estimated capture zone <br /> for extraction wells EW034AU, EW045AU, and EW046AU,however, there are no <br /> monitoring wells downgradient(north) of this area to provide analytical or water level <br /> data to substantiate that the TCE plume does not extend past the estimated capture zone. <br /> Please state the basis for the estimated TCE plume for extraction wells EW034AU, <br /> EW045AU, and EW046AU. <br /> MINOR COMMENTS <br /> 1. Section 5.3.3.4, Plumes in Middle Hydrologic Zone, Page 5-6: There appears to be a <br /> contradiction between this section and the volatile organic compounds(VOCs)table in <br /> Appendix F on the concentration of TCE found in the groundwater sampled at <br /> monitoring well LM073B during the third quarter of 2005 (3Q05). This section states that <br /> the groundwater sampled from monitoring well LM073B during 3Q05 had a TCE <br /> concentration greater than the TCE aquifer cleanup level (ACL) of 5.00 micrograms per <br /> liter(ug/L). However, in Appendix F, Summary of Quarterly Results Reported for Wells <br /> Sampled During 4Q04, 1 Q05, 2Q05, and 3Q05, the table for volatile organic compounds <br /> shows the groundwater sampled from monitoring well LM073B with a detection of 3.70 <br /> ug/L. Please resolve this discrepancy for the monitoring well LM073B TCE <br /> concentration. <br /> 2. Table 5.2-1 Summary of Treatment System Construction and Performance Data, <br /> Page 5-19: It appears that the reference listed for the Five-Year Review should have <br /> been listed for the previous topic (Operation and Maintenance Manuals). Please correct <br /> the references in the next version of the report. <br /> 3. Section 7.1 VOC Plume Changes, Subsection 7.1.1, Page 7-1: The table on this page <br /> states that there is no sample concentration exceeding the tetrachloroethene(PCE) ACL <br /> in the middle zone. However, it appears thatthegroundwater sampled from monitoring <br /> well LM029B exceeded the PCE ACL(5.0 ug/L) at a concentration of 5.30 ug/L, as been <br /> on Figure 5.3-2A (page 5-43) and in Appendix F (page 44). Please resolve these <br /> discrepancies. <br /> 4. Section 7.2 Other Organic Compounds in Groundwater, Subsection 7.2.7,Page 7-2: <br /> It appears that the dates of the cone penetrometer test(CPT) investigation of dieldrin are <br /> described incorrectly in Section 7.2.7. The first and third sentences both state the CPT <br /> investigations were performed in September and October 2005,but Section 4.4.1.4 on <br /> Page 4-7 says the first CPT investigation was performed in 2004. Please resolve this <br /> discrepancy. <br /> 2 <br />