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L \Uwl� <br /> L November 29,2005 <br /> NOA Project Number: E05003B <br /> In the early 1900s,natural levels of nitrate in ground water were measured in forty-three (43) wells <br /> throughout the Sacramento Valley by Bryan (1923). It was thought that ground water at that time <br /> L was close to "natural' conditions. Based on the work by Bryan,it is estimated that under"natural" <br /> conditions,ground water concentration containing nitrate is no more then about 13.5 mg/L-NO3 (3 <br /> mg/L-N). Areas having 24.75 mg/L-NO3 (5.5 mg/L-N) or more are those in which nitrate <br /> concentrations may be increasing (Hull, 1984). <br /> 7 <br /> L DBCP was not detected in the water sample. DBCP is a nematocide and soil fumigant for <br /> vegetables and grapes. It is thought to cause health problems consisting of kidney damage,liver <br /> Ldamage,and cancer. The use of DBCP was discontinued in 1979. The Environmental Protection <br /> Agency (EPA) set the maximum contaminant limit (MCL) at 0.2 parts per billion (ppb) because the <br /> EPA believes that given present technology and resources,this is the lowest level to which water <br /> systems can reasonably be required to remove this contaminant should it occur in drinking water. <br /> 4.5 Well Water Sample Collection, Handling, and Transportation �') �y► <br /> V The sample for nitrate was collected in a sterile plastic container,while the sample for DBCP was � ���° <br /> collected in two sterile glass vials. The samples were then transported on ice and remained under <br /> L chain of custody to Precision Enviro-Tech, Stockton. <br /> 4.6 Chain of Custody �( �� C 'r py�g���G� �► <br /> The Chain of Custody document has been included in the appendix of this report �� <br /> L 5.0 SOIL PROFILE AND GEOLOGIC INFORMATION <br /> The Site is depicted on the USGS Preliminary Geologic Map of San Francisco-San JoseQuadrangle (199 as <br /> L within the Quaternary Modesto Formation. The Modesto Formation is composed primarily of <br /> Arkosic alluvium forming Mokelumne River terraces and alluvial fan; chiefly sand with minor gravel <br /> and silt;probably glacial outwash (Plate 7). <br /> The surface and near surface soils located at the Site are reported by the San Joaquin County Soil Survey <br /> to be composed of Vetitas fine sandy loam, 0-2% slopes and Tinnin loamy coarse sand, 0-2% <br /> slopes. (Plate 8) (USDA, 1992). Table 3 presents some selected properties of these soils: <br /> 6 <br /> '404 <br /> r <br />