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of 200 feet in the northwest part of the San Joaquin Valley near Tracy and pinches out at both the eastern and western margins of the valley. The Middle Tulare, at a depth of approximately 220 below ground surface (BGS), is the very poorly transmissive Corcoran Clay Member, which is estimated to be 220 to 250 feet thick. The Lower Tulare Member has not been encountered in any of the recent groundwater investigation in the Tracy area. The Upper and Lower Members are transmissive zones that are important to the water supply in the San Joaquin Valley (Montgomery Watson, 1998b). Subsurface investigations at DDJC-Tracy have extensively mapped alluvial and fluvial stratigraphy of the Upper Tulare Member and overlying deposits. The Upper Tulare Member has been divided into four geologic units, designated "horizons": Above Upper, Upper, Middle, and Lower (Montgomery Watson 1995a). These horizons were deposited as a result of changes in fluvial flow regime and sediment load over time. The depth,thickness, and lithology of the horizons vary across the area. The horizons consist of fine-to medium-grained deposits of sand, and gravel with varying amounts of sand, separated by fine-grained deposits of silt and clay (Montgomery Watson, 1998b). Evidence from groundwater elevations,hydraulic gradients,and contaminant concentration at DDJC- Tracy indicate that groundwater in the four horizons is in hydraulic communication between the horizons. The clay layers between these horizons do not prevent vertical movement of groundwater (Montgomery Watson, 1998b). Groundwater elevation maps indicate that groundwater flow is generally north-northwest. Since September 1992, vertical hydraulic gradients between the Upper and Middle Horizons have historically been downward; however, vertical gradients between the Upper and Middle Horizons showed no consistent direction in 1998 (Montgomery Watson, 1998b). Private well PW-1 is screened from 85 to 105 feet BGS and PW-3 is screened from 100 to 180 feet BGS. Well completion data is not available for PW-5. The 1994 hydropunch samples were collected at depths of 40 to 44 feet BGS. 2.2 Site Geology and Hydrogeology There are currently two production wells (AP-1 and AP-2) and six groundwater monitoring wells (MW-1, MW-2, MW-3, MW-4, MW-7, and MW-8) on site (Figure 1). The production wells are screened at 60 and 150 feet BGS. The monitoring wells are screened in the Upper Horizon over the interval from 10 to 23 feet BGS. Monitoring wells MW-1 through MW-4 were installed in October, 1989. Monitoring wells MW-7 and MW-8 were installed in June 1997. The groundwater gradient at the site has historically been to the north-northwest. Depth to groundwater measured in December 1998 ranged from 11.68 feet BGS in MW-4 to 14.65 feet BGS in MW-3. 3.0 Scope of Work To achieve the project objective,the following scope of work will be conducted: 1. Permitting and Mobilization IT Corporation Work Plan 3 All Pure,Tracy