SITE INFORMATION AND CORRESPONDENCE_1997

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Levine-Fricke-Recon ENGINEERS,HVDROGEOLOGISTS&APPLIED SCIENTISTS we recommend that three of the six Chevron wells (CHMW-2, CHMW-3, and CHMW-5) be added to the quarterly monitoring program based on their spatial distribution on the property. The Quarterly Monitoring Plan for the project will be revised to reflect this modification and will be submitted to the RWQCB for approval. 3. The Exxon monitoring wells which contain 40-foot screens are not to be used in determining site-wide water level elevations. We acknowledge the RWQCB's position and will not include the Exxon monitoring wells in the quarterly monitoring program. However, based on our evaluation of lithologic data collected during the remedial investigation and Phase I Interim Remedial Action (IRA) field scoping activities, it is LFR's conceptual model that the sediments in the A-zone aquifer act as a single hydraulic unit. We believe water-level measurements collected from Exxon monitoring wells would be comparable to other A-zone monitoring wells installed at Lincoln Center. 4. I concur with the conclusions and recommendations. When will this additional work be completed? The status of the additional work recommended in the "Public and Private Well Survey Report, Lincoln Center, Stockton, California," dated July 21, 1997 ("the Well Survey Report") is as follows: As described in the conclusions section in the Well Survey Report, the scope of the remedial investigation (RI) includes installation of A-, B-, and C-zone monitoring wells at a location downgradient from Lincoln Center, approximately midway between Pacific Avenue and well COS #11 to evaluate the potential for detected Hazardous Substances to migrate from Lincoln Center to downgradient municipal supply wells. In May 1997, monitoring wells were installed in the A-, B-, and C-zones (MW-107A, MW-201B and MW-300C, respectively) on the corner of Emeryn Street and Lincoln Road, approximately midway between Lincoln Center and well COS #11. VOCs, including the Hazardous Substances, have not been detected in groundwater samples collected from these wells in June, August, and November 1997. Based on the results and conclusions discussed from the Well Survey Report, LFR recommended the following actions: Determine the status of domestic wells located downgradient from Lincoln Center identified from San Joaquin County Public Health Services, Environmental Health Division, and Department of Water Resources records. This task will include contacting the owners, if possible. LFR may recommend sampling these wells for VOC analysis. The status of the three domestic wells potentially located downgradient from Lincoln Center is presented in the table below. Lu-Resp-RWQCB-Dec97-04111:SRL 2