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f <br /> April 1, 2005 <br /> NOA Project Number: E05034A <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 /> 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 /> i.. 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 /> -^ DBCP w e water sample. DBCP is a nematocide and soil fumigant for vegetables <br /> p g g <br /> and grapes. It is thought to cause health problems consisting of kidney damage,liver damage, and <br /> Fjcancer. The use of DBCP was discontinued in 1979. The Einvironmental Protection Agency (EPA) <br /> set the maximum contaminant limit (MCL) at 0.2 parts per billion (ppb) because the EPA believes <br /> that given present technology and resources, this is the lowest level to which water systems can <br /> reasonably be required to remove this contaminant should it occur in drinking water. <br /> X4.5 Well Water Sample Collection, Handling, and Transportation <br /> _ The samples were collected in a clean.plastic container, then decanted into clean glass vials. The <br /> samples were then transported on ice and remanded under chain of custody to Precision Enviro- <br /> Tech, Stockton. <br /> k"4.6 Chain of Custody- - <br /> The Chain of Custod 'document.has been included in thea appendix of this report. <br /> Y = pp P <br /> 5.0 SOIL`PROFILE AND GEOLOGIC INFORMATION <br /> The Site is depicted on the USGS Preliminary Geologic Map of the Bellota Quadrangle as within the <br /> Quaternary Modesto Formation. Quaternary Modesto Formation (upper member)- Foothill-derived <br /> alluvial silt, clay, and minor smi <br /> and forming terraces,upper fans�and-following distributaries across <br /> lower fans; abundant volcanic detritus (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 Ramoth sandy loam,-5-8% slopes,Tokay fine sandy loam, 0-2% slopes and Vina <br /> fine sandy loam, 0-2% slopes (Plate 8) (USDA, 1992). 'Table 3 presents some selected properties of <br /> these soils: <br /> E ? <br /> 6 <br />