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a Levine-Fricke-Recon • . DRAFT t Well construction data for wells identified in the Study Area were obtained from the sources described in Section 2.1, in addition to the following: • subsurface investigation reports for the Chevron service station (Sierra Environmental Consultants 1987, 1990, 1992, 1993) • a site assessment report for the former Regal, now Exxon, service station (WEGE 1989) • the Rl/FS Work Plan (LFR 1996a) Well construction data were evaluated to determine whether domestic, municipal supply, and/or monitoring wells identified in the Study Area are appropriate for use in characterizing the groundwater quality and hydraulic characteristics of the Site. Well construction data and lithologic data for selected wells located in the vicinity of the Site were compared to well construction data and lithologic data for existing Site monitoring wells. These selected wells include monitoring wells installed at Lincoln Center and the nearest municipal supply well located downgradient from the Site, well COS #11. Available well construction data for domestic wells located in the Study Area are presented in Table 1. Well construction data for municipal supply wells located in the Study Area and for monitoring wells installed at Lincoln Center are summarized in Table 4. A schematic diagram of well COS #11 is presented in Figure 6. Results of the well construction compilation and evaluation are described in Section 3.2 of this report. 2.3 Compile Groundwater Sample Analytical and Elevation Data The DQOs and data use for this task are to obtain groundwater sample analytical data and groundwater elevation data from identified public and private wells, if available. The groundwater analytical data were used to evaluate whether the identified public and private wells have been or may potentially be affected by Hazardous Substances from the Site. Such wells may act as potential conduits for groundwater containing Hazardous Substances to infiltrate to deeper groundwater zones. Groundwater analytical data will also be evaluated to determine if these data can be used in preparation of the Risk Assessment, if appropriate. Groundwater elevations in the Study Area were evaluated by reviewing maps prepared by the San Joaquin County Flood Control and Water Conservation District (SJC FCWCD). Since the fall of 1971, SJC FCWCD has monitored groundwater levels and published the data in semiannual reports. The data are compiled from federal, state, and local government agencies as well as non-government sources. These data include groundwater elevation data collected from municipal supply wells during periods when the wells are not being pumped to measure static conditions. The most current Page 4 4111WELL.AMI:AM1