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... Mr.Jadi Singh <br /> January 24,2003 <br /> Job Number:LE02481 <br /> Page 4 <br /> ground water depth below ground surface as 6,2 1, the lowest depth as 11.22 fleet below the <br /> ground surface, and the flow direction as northwest. Drinking water wells and surface water are <br /> �. reported to be affected by the leak. <br /> Three monitoring wells on the subject property were abandoned on September 19, 1997, under <br /> the supervision of Fluor Daniel GTI. The April 16, 1998 report prepared by Fluor Daniel GTI <br /> states that MW 1 "historically has not contained petroleum hydrocarbons above detection limits," <br /> i., while MW2 and MW3 "have historically contained varying concentrations of petroleum <br /> hydrocarbons." <br /> The subject property was issued a no further action letter with regard to the underground tank <br /> release by EHD on May 7, 1998. <br /> 4.0 HYDROGEOLOGIC SETTING <br /> 4.1 Geology and Soils <br /> The surface geology at the site is shown on a geologic map mapped by Atwater(1982). The area <br /> is mapped as the Holocene age alluvial-floodplain deposits, undivided. The soil/sediment on the <br /> site was composed of an unconsolidated, medium dense,brown silty sand similar to the Lodi <br /> area silty sands located adjacent to the Mokelumne River. The geologic map indicates that a <br /> ,6o paleo-drainage exists approximately 400 feet north of the site. It is a remnant of a past creek <br /> which had meandered through the town of Thornton. <br /> The surface soils at the site are reported to be Sailboat silt loam(no. 234). The San Joaquin Soil <br /> Survey describes the soil as a very deep, somewhat poorly drained,nearly level soil on flood <br /> plains (USDA, 1990). It formed in alluvium derived from granitic rock sources. Permeability is <br /> .. moderately slow in the Sailboat silt loam.. <br /> Neil O. Anderson&Associates drilled six shallow percolation test holes on November 21, 2002 <br /> and November 21, 2003 and one 14-foot deep ground-water test hole_ In addition, two double <br /> ring infiltrometer tests were performed on the surface soils to measure the infiltration rate(Plate <br /> 1). <br /> A deep ground water/soil boring was drilled to a depth of 14 feet. Several shallow percolation <br /> .� test borings ranging from l foot to 3 feet deep were also drilled on the property. The following <br /> soil log represents the 14 foot deep ground water/soil boring and is representative of the soil <br /> �pE R,pO <br /> r s <br /> s <br /> f y <br /> •� Q 4 <br /> r <br />