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MEMORANDUM • <br /> CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD - CENTRAL VALLEY REGION <br /> 3443 Routier Road, Suite A Phone: (916) 361-5600 <br /> Sacramento, CA 95827-3098 ATSS Phone: 8-495-5600 <br /> TO: Antonia K. J. Vorster � � FROM: John J. Tomko <br /> Senior Engineer I Associate Engineer <br /> San Joaquin Regulatory <br /> DATE: 29 July 1990 SIGNATURE: <br /> SUBJECT: REMEDIAL INVESTIGATION REPORTS, NESTLE FOODS CORPORATION, RIPON, SAN JOAQUIN <br /> COUNTY <br /> ADDENDUM TO THE PHASE V REMEDIAL INVESTIGATION REPORT <br /> On 15 May 1990 we received an addendum to the Nestle Phase V Remedial Investigation <br /> Report and Phase VI workplan based upon Mr. Gary Reents' comments of 30 March 1990. <br /> I've reviewed these responses and determined that they are adequate. Due, in part, to <br /> Gary's comments, Nestle's Phase VI investigation will include the following: <br /> 1) The definition of aquifer cleanup goals and remedial alternatives, and an <br /> identification of data gaps (possibly requiring additional plume delineation <br /> monitoring wells) , and the development of a 3-D groundwater model . <br /> 2) Time trend analyses of contaminant concentrations at each monitoring well , <br /> and contaminant concentration contour maps for those volatile organic <br /> chemicals identified in the Risk Assessment as posing the greatest risks. <br /> 3) A reevaluation of previously prepared geologic cross-sections to ensure <br /> correct aquifer zone designations and lithologic correlations, and that the <br /> cross-sections are drawn parallel and perpendicular to ground water flow <br /> paths. <br /> 4) A revaluation of the temporal changes in groundwater flow characteristics <br /> (direction and magnitude) , via the groundwater flow model . <br /> 5) A summary table of QA/QC results from the Phase V sampling round and all <br /> subsequent sampling rounds. <br /> 6) The conductance of a quantitative aquifer test to determine how nearby <br /> municipal and industrial production wells (including the Nestle production <br /> well ) influence the local groundwater system. The information gained from <br /> this test will be used to estimate aquifer hydraulic conductivity. <br /> 7) The evaluation of the need to conduct a long-term aquifer pump test to <br /> provide the hydrological data necessary to effectively design an aquifer <br /> remediation system. If it is determined that an aquifer pump test is <br /> required, than a work plan for such a test will be submitted. If it is <br /> determined that this test is not required, the rationale for this <br /> determination will be presented. <br />