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portion of the Great Valley has been filled with as much as six miles of sediment deposited by rivers and streams draining from the western margins of the Sierra Nevada(USGS, 1986). Hydrogeologically,the Site is located within the Eastern San Joaquin Subbasin of the San Joaquin Groundwater Basin, covering a surface area of 1,105 square miles. The Site and surrounding area are underlain by the alluvium and Modesto/Riverbank Formations, formed by coalescing alluvial fans of Recent to Late Pleistocene age. These sediments consist of more than 150 feet of sands and gravels within the alluvial fans deposits and clay, silt and sand within the interfan deposits. Groundwater within these deposits is unconfined(DWR, 2006). The nearest surface waters to the Site are the Smith Canal, located approximately 0.25 miles to the north, and the San Joaquin River, located approximately 0.9 miles to the north. SITE GEOLOGY AND HYDROGEOLOGY Near surface soils in the vicinity of the Site are described as Holocene age flood basin deposits consisting of clay silts and some sands (USGS, 1986). Previous subsurface investigations completed at the Site, and in the Site vicinity, have involved the drilling of wells and exploratory borings to depths of up to 125 feet below ground surface (bgs). Soils encountered during the drilling and advancement of cone penetrometer(CPT)borings have consisted of interbedded layers of clay, clayey silts, silty sands, and poorly graded sands of varying thicknesses. Three primary water bearing zones have been interpreted to occur beneath the Site between the approximate depths of 10 and 25 feet bgs (shallow zone), 40 and 60 feet bgs (intermediate zone), and greater than 70 feet bgs (deep zone). Subsurface geologic section lines are shown on Figure 4 and subsurface geologic sections are presented in Figures 5 through 7. The direction of groundwater flow in the shallow water bearing zone has been interpreted to range from north to northeasterly. Groundwater flow in the intermediate water bearing zone has been interpreted to be predominately west to northwesterly. Groundwater flow in the deep water bearing zone has been interpreted to be predominately north to northwesterly. Historically, depth to groundwater in the shallower screened monitoring wells has ranged between approximately 7 and 12 feet bgs. Depth to groundwater in the intermediate screened monitoring wells has ranged between approximately 8 and 14 feet bgs. Depth to groundwater in the deep screened monitoring wells has ranged between approximately 10 and 15 feet bgs. Historic groundwater levels and chemical analysis results are presented on Table 1, and rose diagrams showing historic estimated groundwater flow directions are presented as Figures 8 through 10. OBJECTIVES The objectives of this scope of work are to advance two soil borings using a cone penetrometer test (CPT) rig to interpret subsurface soil lithology and collect soil samples at the location of proposed biosparge well BSW-1, and install a biosparge well near groundwater monitoring well MW 16. The new biosparge well will be utilized in biosparge feasibility testing and in future remedial operations to promote bacterial growth to breakdown petroleum hydrocarbons in the intermediate and deep groundwater zones beneath the Site. FREY Environmental, Inc. 2 Project No. 1175-01