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STATE OF CALIFORNIA- Environmental Prota Agency • PETE WILSON, Governor <br /> CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD <br /> CENTRAL VALLEY REGION cALTII yy <br /> 3443 Routier Road, Suite A <br /> Sacramento, CA 95827-3098 _5 c PPI y - a„ <br /> FAXN9116) 255-3015 916) 3 00 �.J DEC 2: 37 <br /> 1 December 1993 <br /> Mr. Patrick Riddle <br /> 7574 Shoreline Drive <br /> Stockton, CA 95219 <br /> COMMENTS ON THE DRAFT' WORK PLAN, LINCOLN VILLAGE CENTER, SAN <br /> JOAQUIN COUNTY <br /> We have reviewed the 15 October 1993 draft work plan for Lincoln Village Center (LVC). The <br /> objectives of the work plan are to describe site conditions; propose investigative actions to identify <br /> and characterize air, soil, and ground water contaminant pathways; and describe work that will be <br /> performed to determine appropriate remedial action alternatives. Our comments on the work plan, <br /> which are described in detail in the attached memorandum, are summarized below. <br /> 1. Chevron's monitoring wells should be included in the sampling program since some of them <br /> have contained PCE. <br /> 2. The work plan should propose additional investigation and extraction wells in the Village <br /> Cleaner plume. The 1989 soil gas survey report stated that it was not clear whether the <br /> source of the PCE vapor was the sewer, contaminated soil, or contaminated ground water. <br /> The uncertainty in the PCE vapor source provides justification for more investigation in the <br /> identified source areas. Regardless of the source, the PCE vapor is a threat to water quality <br /> and must be remediated. <br /> 3. More than one upgradient well is needed in Zone A. <br /> 4. In Zone C, the extent of contamination, ground water flow direction and gradient, and <br /> hydraulic connection with Zone B need to be identified. The work plan must specify the <br /> activities to achieve these objectives. <br /> 5. An upgradient monitoring well in Zone B is needed. <br /> 6. Upon completion of MW-IOC, there will be only two monitoring wells in Zone C. Since the <br /> LVMD wells have been abandoned, another well in this zone is needed to allow <br /> determination of ground water flow direction and gradient. <br />