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• MEMORANDUM • <br /> CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD • CENTRAL VALLEY REGION <br /> 3443 Routier Road, Suite A Phone: (916) 255-3000 <br /> Sacramento, CA 95827-3098 CALNET: 8-494-3000 <br /> TO: Wendy L. Cohen�W FROM: Philip S. Isorena <br /> Senior Engineer Associate Engineer <br /> DATE: 1 December 1993 SIGNATURE: <br /> SUBJECT: COMMENTS ON THE DRAFT WORK PLAN, LINCOLN VILLAGE CENTER, <br /> SAN JOAQUIN COUNTY <br /> I have reviewed the 15 October 1993 work plan for Lincoln Village Center (LVC). The objectives <br /> of the work plan are to describe site conditions; propose investigative actions to identify and <br /> characterize air, soil, and ground water contaminant pathways; and describe work that will be <br /> performed to determine appropriate remedial action alternatives. My comments on the work plan <br /> follow. <br /> 1. Figures 10 and 11 in the work plan show the lithologic units beneath the site to be continuous. <br /> Comment: As stated in Board staff memos of 18 December 1989 and 26 June 1991, the boring <br /> logs for the San Joaquin County wells and the LVC monitoring wells show that the lithologic <br /> units are heterogeneous and not continuous. Therefore, Figures 10 and 11 are incorrect. <br /> 2. Page 11 of the work plan states that in December 1990, 47.0 ppb of tetrachloroethylene <br /> (PCE), 8.5 ppb of trichloroethylene (TCE), and 5.8 ppb of cis-1,2 dichloroethylene (DCE) <br /> were detected in ground water samples collected from LVMD 2, and 26 ppb of PCE were <br /> detected in LVMD 6. The work plan then states that no VOCs have been detected in MW 30, <br /> which is screened in the Zone C or any other LVMD wells in the immediate vicinity of LVC, <br /> including LVMD 6. The ground water sampling results are summarized in Table 2-2. <br /> Comment: The above statements are obviously contradictory. The level of contamination, <br /> ground water flow direction, and gradient in Zone C need to be confirmed. Table 2-2 is <br /> confusing because two dates, such as December 1990 - January 1991, are shown for each <br /> sampling event. Also, no explanation is given for the asterisks. <br /> 3. Page 14 of the work plan states that well sampling, water level measurements, ground water <br /> level maps, isoconcentration contour maps, and horizontal and vertical gradients are required <br /> before implementing any field work. <br /> Comment: I concur that preliminary activities are needed prior to commencing the field <br /> investigation program so that the existing site data can be compiled and updated as required. <br /> Chevron's monitoring wells should be included in the sampling program since some of them <br />