SITE INFORMATION AND CORRESPONDENCE

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1 Interim Remedial Action - 2- • 19 March 1999 Nestle Beverage Company To meet these objectives Nestle proposed, during this meeting, one additional extraction well (E-3) located (approximately) between the M-5 monitoring well cluster and the municipal water supply well MW-7. The purpose of this additional extraction well (E-3) is to provide hydraulic control of the TCE plume and also prevent additional impacts to the MW-7 supply well which. _. has detected TCE (April 1998-1.8 ppb). As was agreed, an extraction well in this area will be constructed and operational no later than 3 June 1999. To assure that extraction well E-3 is constructed and operational by 3 June 1999, we request that Nestle submit an additional installation Work Plan for E-3 no later than 15 April 1999. 3. Based on the 1 I March 1999 meeting and earlier conversations with your consultant, IT Corporation, remediation of the TCE plume near municipal well MW-7, must be closely coordinated with the investigation and remediation of MTBE contaminated groundwater that appears to be associated with a Shell Gasoline Station located at 341 East Main Street, Ripon California. Site investigation data for the Shell Station provided by the San Joaquin County Public Health Services on 18 March 1999, indicate MTBE concentrations ranging from 141 4g/1 ems¢ —a to 3010 µg/l in groundwater. Plume maps provided by Nestle, detections of TCE in one domestic supply well located on 233 Parallel Avenue,(Ripon California) and detection of TCE IYItGt l Up=/x in municipal supply well MW-7 suggest that Nestle's TCE plume is in proximity to the MTBE groundwater plume associated with the Shell Station. Construction of an extraction well in this area must be designed in such manner that it will not exacerbate the MTBE groundwater plume. Svi'S urAa.R A6�S u�,taa �iR u�J�� baun n ,b Z. 3 4. It was discussed, during the 11 March INWproject meeting, that an additional extraction well (E-4) could be placed on the southeast boundary of the facility(approximately between monitoring wells M-2 and M-12). The purpose of this extraction well is to provide hydraulic r containment of the TCE plume in this area and prevent further impacts to municipal supply well MW-9. Further evaluation of an extraction well southeast of the facility (either on or off-site of the Nestle property) should be conducted after additional plume definition is provided in this area. Specifically,Nestle will determine the extent of the TCE plume based on analytical data obtained from the Simpson wells. After this information becomes available,Nestle should be able to determine an optimal location to provide groundwater remediation in this area and provide containment of the TCE plume migrating towards municipal well MW-9. We request that Nestle provide proposals for additional extraction well(s) (i.e. E-4) no later than 15 June 1999 which would provide plume capture southeast of the facility. 5. The design specifications for the proposed GAC system (for extraction well E-2) provided in the Work Plan indicates that flow rates of up to 250 gpm could be treated by this system. Nestle should evaluate if additional extraction wells could be installed (near monitoring well cluster M- 8) or if greater flows can be extracted from extraction well E-2, to provide greater hydraulic control of the TCE plume in this area. An evaluation to determine optimal location for additional extraction well locations should be conducted as part of the pre-design activities. This evaluation should be presented in the installation work plan, discussed above, for extraction well E-3.