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1 <br /> I <br /> The nearest surface water bodies of significance include Mosher Creek, approximately 6,500 feet <br />' northwest of the site, and the Calaveras River, located approximately 6,000 feet southeast of the <br /> site These two waterways flow in a westerly direction. The Calaveras River generally exhibits <br />' moderate stream flow losses over portions of the year, which contnbutes to groundwater recharge <br /> (USGS Professional Paper 1401-D, 1989) Existing and potential beneficial uses of these surface <br />' water bodies include municipal and domestic water supply, irrigation, stock watering, industrial <br /> supply, groundwater recharge, freshwater replenishment, recreation, freshwater habitat, wildlife <br />' habitat, fish migration, and fish spawning (CRWQCB-Region 5 Water Quality Control Plan, <br /> 1994). The "older alluvium" is the most extensively developed geologic unit in the area and hosts <br /> Iboth unconfined and confined zones The unconsolidated, mostly coarse-grained nature of the <br />' aquifer material results in high well yields Specific capacities of wells completed in the older <br /> alluvium average 42 GPM/ft (USGS Professional Paper 1401-D, 1989) <br />' Drinking wells in the region are generally completed at depths greater than 130 feet below ground <br /> surface (bgs) due to the relatively poor quality of near surface groundwater <br /> Regional groundwater flow in the site area is generally in a northeasterly direction toward a <br /> regional groundwater depression centered about 4 miles northeast of Stockton (San Joaquin <br />' County Flood Control and Water Conservation District, Fall 1998) <br /> 1 Published data from the San Joaquin Flood Control and Water Conservation District indicate that <br /> the average long term depth to groundwater at the site has vaned from approximately 55 feet bgs <br />' (Spring 1986) to 80 feet bgs (Spnng 1993) Current depth to groundwater at the site is <br /> approximately 59 feet bgs <br /> 3.3 Previous Investigations <br /> On January 28, 1998, three 8,000-gallon gasoline USTs, dispenser pumps, and associated piping <br /> were removed from the property Soil contamination was noted during UST removal operations <br /> and soil samples collected from beneath the removed USTs and pump island revealed significant <br /> levels of petroleum hydrocarbon constituents The location of the former USTs, dispensers, and <br />' 4 <br /> data/groundze/tuleburg/reports/mud_has_wellrcport.doc <br /> 1 <br />