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Mr. Maurice Benson <br /> July 28, 2009 <br /> Page 2 <br /> to areas north of extraction well (EW) EWCC3 but also at EWCC3 and <br /> up-gradient to the east of the extraction well. <br /> 3. Page 2-4, section 2.3.3.4: The report mentions the VOC plumes in the south <br /> balloon migrating 400-800 feet to the west towards "...an agricultural well that is <br /> no longer in operating." The site history and the housing development west of <br /> DDJC-Sharpe would have precluded the operation of any agricultural well for at <br /> least 15 years and therefore unsure why this is provided as rationale for the VOC <br /> plume migration, unless for a historical perspective. The timeline of the VOC <br /> plume's migration would be useful to better understand the section and whether it <br /> is discussing more recent observations or that of a historical perspective for the <br /> contaminant distributions. <br /> 4. Page 2-4, section 2.4.1.1: On-Depot Receptors; DTSC recommends mentioning <br /> the DDJC-Sharpe Potable Well Contingency Plan because this document is <br /> responsible for the planning and implementation of policies and procedures for <br /> protecting the on-base workers from contaminants of concern in the bases' <br /> potable water supply. <br /> 5. Page 2-1, section 2.2.2.1, Conceptual Site Model (CSM): The section states that <br /> the CSM has been updated with 2007/2008 Hydropunch® data. DTSC is aware <br /> that the CSM also includes groundwater data from existing monitoring wells but <br /> there is no distinction between how the two forms of data are being interpreted or <br /> used. The State has previously stated that there needs to be a distinction in how <br /> the two sampling methods are interpreted and presented and should not be <br /> interchanged for one another. <br /> 6. Figure 2-2: The dashed line denoting the off-depot areas with potable wells and <br /> contaminant plumes should be more pronounced as the current line is much <br /> thinner than indicated in the legend and becomes somewhat hidden when <br /> running adjacent to the DDJC-Sharpe boundary line. Figure 2-2 should be <br /> modified to present area boundaries consistent with those presented in Figure's <br /> legend. <br /> 7. Figures 2-3 thru 2-5: DTSC notes that the boundaries representing offsite <br /> potable wells with DDJC-Sharpe contaminant plumes are depicted in the figures <br /> but not presented in the respective figure legends. DTSC recommends adding <br /> the appropriate dashed line with supporting information in each of the respective <br /> Figures for clarity and consistency. <br />