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r' STATE OF CALIFORNIA-Environmental Protectio . ency • PETE WILSON, Governor CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD CENTRAL VALLEY REGION I ",L HEALTH 3443 Routier Road, Suite A Sacramento, CA 95827-3098 AUGn1 pyo ! PHONE: (916) 255-3000 Jai G 10 PH 1: 11 FAX: (916)255-3015 9 August 1994 Mr. Frank Zumstein Nestles Beverage Company 230 Industrial Ave. Ripon, CA 95366 FINAL REMEDIAL INVESTIGATION REPORT, NESTLES BEVERAGE COMPANY, RIPON We have reviewed the Final Remedial Investigation Report, Nestles Ripon Facilitv. received February 1, 1994. The report is well written and the data are presented in easily discernable format. This report presents a good description of all past remedial work at this facility. Even though extensive investigative has been performed we believe, based on data presented, that further investigation is necessary to complete the remedial investigation. For example, the report discusses several possible source areas but, the vadose zone contamination has not been characterized. Also several ground water units are not well enough defined to describe the complete extent of the contaminant plume. This work will have to be done before remedial design can be completed. Below is specific comments on the Final Remedial Investigation Report: I. Section 4.1 Ground Water, Paragraph 2; The report states, "Non-detections in production wells, however, were considered in defining the extent of impacts in all units." This appears inappropriate. Many production wells cover several ground water units and nondetect in a well may represent dilution rather than no contamination in any of those units. In general production wells should not be used in plume definition. II. Section 4.2.2 Soil Gas Sampling Results, Paragraph 1; The report states, " Although the industrial sewer located along Industrial Avenue and Fourth Street has been considered as a possible explanation for elevated TCE in this area, samples taken from the sewer and wells near the sewer in 1992 indicate that the sewer is not a potential source." This statement does not appear to be supported by the data. Monitoring well M-8, which is adjacent to the sewer line, showed the highest TICE concentration in the first ground water unit. All monitoring wells adjacent to the sewer show detectable levels of TCE. Also since the TCE discharge to the sewer line occurred over 20 years ago, it is likely that samples directly from the sewer would not detect TCE. III. Section 4.2.3 Soil Vapor Extraction, Paragraph 4; This paragraph provides only a cursory description the eight months of vapor extraction system results following 10 January 1988 start-up at vapor extraction well VE-4. During those months the concentration leaving the extraction well increased from nondetect to over 10ppm of TCE. This increase indicates a source area within the sphere of influence of VE-4, but not right at the location of VE-4. This source area should be identified, and its lateral and vertical extent determined, in order to more effectively remediate it. IV. Section 5.1 Transport Media, Paragraph 1;