SITE INFORMATION AND CORRESPONDENCE_1

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PUBLIC HEALTH SERVICES Pa...N SAN JOAQUIN COUNTY 2: ENVIRONMENTAL HEALTH DIVISION r `r < i Ernest M. Fujimoto, M. D., M.P.H., Acting Health Off r Id 't. 304 E. Weber Ave., Third Floor • P. O. Box 388 • Stockton, CA 9 .l- 88 209/468-3420 .SEP 12 1996 PARMACEAST RICHARD FISH W L SIMMONS DEL MONTE FOODS C/O SIDNEY RUDY ESQ 205 NORTH WIGET LANE 333 MARKET STREET WALNUT CREEK CA 94598 SAN FRANCISCO CA 95105 RE: Del Monte/Disco SITS CODS: 2498 110 N. Filbert Street Stockton, CA San Joaquin County Public Health Services, Environmental Health Division (PHS/EHD) has reviewed the "Quarterly Monitoring Results" dated July 1996, prepared by CH2M Hill for the above referenced site. Groundwater samples from monitoring wells MW-DIS-1 and MW-DIS-2 still require dilution prior to analysis. Groundwater levels are above the screened interval of all the monitoring wells. Therefore, it is hard to evaluate the results, but it does appear that concentrations of contamination have increased in MW-DIS-1. This may be due to the fact that the vapor extraction/air sparge system is no longer operating and/or that contamination in the soil previously in the vadose zone is releasing into the groundwater as the water levels rise. Since SVE-3 and SVE-4 are screened from 55 to 75 feet below grade, water samples should be collected and analyzed from one of these wells in future water sampling events. The soil sample results from the drill cuttings from SVE-4 and the boring log notations of odor from 10 feet to 70 feet below grade, confirms there are contaminants in the soil that are continuing to leach into the groundwater. This source must be remediated. If SVE-3 and SVE-4 were screened from So feet to 70 feet below grade, as agreed to by Del Monte in a November 29, 1995 letter, they could be connected to the vapor extraction system and vapor extraction could continue. If groundwater levels do not decline, PHS/EHD will direct you to install properly screened vapor extraction wells. It should be noted that the Final Remediation Plan previously submitted was not approved by PHS/EHD, that the current work is interim, and that a Corrective Action Plan (CAP) must be submitted that complies with the requirements of the California Code of Regulations (CCR) , Title 23, Division 3, Chapter 16, Section 2725 (d) . Once the CAP is approved by PHS/EHD it should be submitted to the State Water Resources Control Board Cleanup Fund Program for reimbursement cost preapproval. PHS/EHD does not agree that dissolved oxygen (DO) is lower in the area around the zone of significant contamination. The DO level of .2 mg/L existed in MW- DIS-2 (which is in the zone of significant contamination) , MW-DIS-8, and MW- DIS-9 (which are outside the zone of significant contamination) . PHS/EHD does not agree that there is a pattern of declining nitrate concentration around the zone of significant contamination. The nitrate level of <.02 mg/L existed in MW-DIS-2 (which is in the zone of significant contamination) and MW-DIS-3 (which is outside the zone of significant contamination) . The August 1996 nitrate results from these wells and MW-DIS- 8S will provide more data on nitrate levels. A Division of San Joaquin County Health Care Services