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i The near surface geology of the region is comprised of unconsolidated alluvial deposits of Pleistocene to Holocene age. These deposits, sometimes referred to as the "older alluvium, consist of intercalated beds of gravel, sand, silt and clay. Underlying the older alluvium are Plio/Pleistocene continental deposits of similar derivation and lithology. The site is situated on level terrain underlain by flood basin deposits of Pleistocene and Holocene age. These sediments are composed of clay, silt, and some sand In the San Joaquin Valley, the Flood Basin Deposits (Holocene) have been estimated to be as much as 100 ft thick. Because of their fine-grained nature, the flood basin deposits generally do not yield much water to wells and impede the vertical movement of water. The majority of groundwater used for irrigation and drinking water supply in the Stockton area is extracted from more permeable zones beneath the flood basin deposits. Drinking wells in the region are generally completed at depths greater than 100 feet below ground surface due to the relatively poor quality of near surface groundwater. Regional groundwater flow in the vicinity of the site is expected to be generally northeasterly away from the Stockton deep water channel and toward a large pumping depression on the northeast side of Stockton. The nearest body of surface water is the Port of Stockton deep water channel located approximately 3000 feet southwest of the site. SITE SAFETY PLAN Field work performed at the site by Ground Zero on behalf of Mr. Jay Freidman was conducted in accordance with Ground Zero's Site Safety Plan No. 015, dated May 9, 1995. This Plan describes the basic safety requirements for drilling soil borings, installing monitoring wells, and groundwater sampling at a site potentially contaminated with petroleum hydrocarbons. The Site Safety Plan is applicable to personnel and subcontractors of Ground Zero. Personnel scheduled to work at the site were briefed on the contents of the Site Safety Plan before work began. A copy of the Site Safety Plan was kept on-site and was available for reference by appropriate parties during work at the site. The Ground Zero Field Geologist was the Safety Officer on-site. FIELD WORK Soil Borings On May 22-23, 1995, a Ground Zero geologist supervised Spectrum Drilling Company (Spectrum) of Stockton, California, drill three soil borings (SB 1, S132, and SB3) to approximately 46 ft below ground surface. Spectrum used a CME-55 drill rig equipped with 6-inch outside diameter (o.d.), hollow-stem augers to drill the borings. An additional boring subsequently • completed as monitoring well MW 1, was drilled.to a depth of 62.5 feet using 8-inch augers. 5