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Mr. Marshall Cloud <br /> September 27. 2007 <br /> Page 2 <br /> Ground water sampling was conducted at 90 DDJC-Sharpe monitoring wells through <br /> low-flow sampling techniques and submersible pumps. Ground water samples were <br /> analyzed for major cations, anions, TDS, and selected trace elements. <br /> Conclusion <br /> The data collected during this investigation characterized the vertical and horizontal <br /> extent of ground water salinity in ground water beneath DDJC-Sharpe and off-site <br /> areas, and evaluated the potential for ground water in the area to qualify for <br /> non-beneficial use classification if ground water salinity and water quality parameters <br /> exceed standards. The investigation's analytical data indicates that DDJC-Sharpe is <br /> not currently impacted by the saline front, and ground water data from monitoring wells <br /> do not show any increasing salinity trends. Concentrations of chloride and TDS data <br /> collected during the fieldwork averaged 117 and 673 mg/L, respectively, from B and <br /> C-zone wells. Similar data from the C and D-zone wells showed concentrations of <br /> 68 mg/L for chloride and 385 mg/L for TDS. <br /> DDJC-Sharpe's ground water pumping appears to affect only the distribution of <br /> localized chloride in the C-Zone aquifer and has not been shown to have contributed to <br /> the presence of high chloride concentrations in offsite areas. Furthermore, ground <br /> water data indicates that DDJC-Sharpe's ground water is unlikely to become impaired to <br /> a non-beneficial use classification in the near future as originally perceived by <br /> DDJC-Sharpe. Regional pumping by non-DDJC-Sharpe entities is unlikely to escalate <br /> the salinity concentrations in DDJC-Sharpe onsite ground water to a point which <br /> qualifies it as a non-beneficial use aquifer. DTSC concurs with DDJC that no further <br /> ground water sampling for the purpose of evaluating the potential of the aquifer to <br /> qualify for a non-beneficial use classification is necessary. <br /> If you have any questions or comments regarding this letter, please feel free to contact <br /> me at (916) 255-3713, or e-mail me at pmacnichC@dtsc.ca.gov. <br /> Sincer <br /> Peter MacNicholl, P.E. <br /> Remedial Project Manager <br /> Federal Facilities Unit <br /> cc: See DDJC-Sharpe Distribution List. <br />