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fi r ' had occurred in the vicinity of the former gasoline tank, and that further investigation was warranted. On August 24 and 25 1994 Remcor installed an g � additional seven soil borings and three monitoring wells to further define the lateral extent of soil and ground water contamination identified in the initial phase of work. To date the lateral and vertical extent of ground water contamination have not been defined. 1.3 Geology The subsurface geology of the site was determined by logging soil samples collected at various intervals during the initial and supplemental site investigations. The maximum depth of boring was 18 feet below grade. Dark brown silty clay dominates the stratigraphy from within one foot of the surface to the bottom of the borings. In general, fine sand was found within the silty clay unit near the L bottom of the borings. The moisture content increased with depth and reached saturation between 12 and 16 feet below surface grade (bsg). LJ 1.4 Hydrology Groundwater at the site is contained in a semi-confined or unconfined aquifer 10 to 15 feet bsg. Historically, groundwater at the site demonstrates a shallow gradient which slopes to the northwest. �I 1.5 Nearby Well Survey �f On August 3, 1995, a visual well survey.was conducted. No domestic or agricultural wells were observed in an approximate 2,000 foot radius of the site. According to Mr. Reuben Amezquita of the City of Tracy, Public Works Department, no city wells are located within 2,000 feet of the site. Two water supply wells (northern and southern) are located on-site near the northwest E� corner of the fencelme. The northern supply well is the primary source well and was installed in 1984. Total depth of this well is reported to be 160 feet with the screened interval from 120 feet to 150 feet. AGS was unable to obtain further information regarding the condition of the two supply wells. i i American Geological Services,Inc. CA95DE-029 3 .