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LFR Levine-Fricke I upper zone by the Corcoran Clay (Ecology and Environment, Inc. 2002). Regionally, recharge of the upper water-bearing unit is primarily from irrigation and seepage of surface water through the alluvium with little contribution from rainwater (USGS j 1971). The project site receives an approximate average of 10.5 inches of precipitation per year and has a total estimated evapotranspiration rate of 61 inches per year as measured 3 miles south of the Site in Tracy, California. Based on data collected from four on-site groundwater monitoring wells during October 2002, groundwater flow within the upper water-bearing unit is toward the northwest, with a calculated gradient of 0.001 foot per foot (Ecology and Environment, Inc. 2002). Review of DWR well logs for wells within a 1-mile radius of the Site indicates that most water supply wells reviewed are completed in the upper water bearing unit above the Corcoran Clay although some irrigation, industrial, and municipal wells draw water from both the upper and lower water bearing units. I There are two industrial groundwater supply wells within a 1-mile radius of the Site. One is located at the adjacent Teichert facility; the other is located at the adjacent RMC Lonestar facility. The construction details are not available for these two wells. The nearest residence is located approximately 0.5 mile east of the Site. The nearest surface-water features to the project site are Corral Hollow Creek to the north, an intermittent natural drainage course; the Delta-Mendota Canal, an irrigation canal; and the California Aqueduct. The topographic nature of the Site precludes it as a potential source of runoff to any of these water features. Because the Site is a former gravel mine, it is essentially a closed basin with no outfall. All rainwater that falls onto the Site infiltrates into the soil substrate and serves as local groundwater recharge. The Water Quality Control Plan, Sacramento River and San Joaquin River Basins (RWQCB, 1998) designates beneficial uses, establishes water-quality objectives, and contains implementation plans and policies for all waters of the Basin. The designated beneficial uses of the groundwater, as specified in the Basin Plan, are domestic and municipal, agricultural, and industrial supply. As stated previously, there is no surface- water flow into or out of the project site because it is located in an excavated pit. 1.3 Objectives i Groundwater elevation data previously collected at the Site indicate that groundwater flow in the upper water-bearing unit is toward the northwest (Figure 3). Based on this flow direction, and the orientation of existing monitoring wells at the Site, an additional groundwater well is needed to provide groundwater-quality data downgradient from the Site. The objective of this work plan is to install a groundwater monitoring well to address this data gap. In addition to this monitoring well, one production well will be installed for dust control measures during remedial activities. This work plan also includes a quarterly groundwater sampling plan designed to establish trends in the concentrations of chemicals in groundwater, and to assess potential impacts to groundwater associated with the waste tire material at the Site. Page 2 Tracy-gV7y-s=p-rpt-wrkp1n(fmW):IEE a