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r� <br /> between 39 and 40 feet below grade in the bore hole, indicating that <br /> the water is confined. The static water level appears to be at a depth <br /> - of approximately 37 feet below grade. The thickness of the water <br /> bearing layer appears to vary from less than 1 foot to more than 10 <br /> feet in the vicinity of the excavation. <br /> There are currently six 4-inch-diameter monitoring wells installed <br /> on the site. Measurement of depth to groundwater in the three of <br /> these wells showed a northerly groundwater gradient with a slope of <br /> 1 foot per 1000 feet (0.001)• Monitoring well recharge rates were <br /> estimated during development and appear to range from 20 gpm to 60 <br /> gpm. <br /> There is one production well located on the site approximately 500 feet ' <br /> south of the excavation. The well previously provided the mill with <br /> water for sanitary use and for the fire sprinkler_ system. A <br /> groundwater 842Pple was collected from the:well on January 22', 1990. <br /> No.be �' <br /> nzene, toluene, .ethylbenzene or xylene, were::detected in that <br /> 'sample.. The well is not currently in'use.„There are no other knownwells within 500 feet of the investigation site. <br /> Surface water in the area is limited to French Camp Slough, which <br /> runs northeast st approximately 1.500 feet from the site. French Camp <br /> Slough is a tributary of the San Joaquin River that flows northward <br /> approximately 3 miles to the west of the site. <br /> 3 On-site borings encountered sequences of clay and sand to a total <br /> depth of 60 feet. The typical geologic sequence encountered is shown <br /> below. <br /> Depth L <br /> fU <br /> D ri n f f rm i n <br /> 0-25 clay <br /> 25-35 <br /> coarse sand <br /> 35-45 fine sand grading to sandy clay <br /> 45-50 clay with intermittent sand lenses <br /> 50-60 clay <br /> Detailed descriptions of the lithology beneath the site are presented in <br /> Section 3. <br /> 1-5 <br />