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L <br /> November 20,2003 <br /> Job Number: LE03-421 <br /> Page 6 <br /> L 4.6 Water Sample Analytical Results <br /> LNitrate as nitrogen was found at 5.51 mg/L-NO3,well below the maximum contaminant level set <br /> by the United States Environmental Protection Agency of 45 mg/L-NO3. DBCP was not detected <br /> in the water sample. The analytical reports prepared by Precision Enviro-Tech can be found in <br /> Lthe appendix of this report. <br /> The presence of nitrates is not uncommon in shallow ground water aquifers in San Joaquin <br /> L <br /> County and other parts of the Central Valley. Nitrate in ground water occurs as a result of the <br /> application of fertilizers, livestock waste, and untreated septic tank waste. Nitrate is mobile and <br /> often accumulates in the shallow ground water zones. <br /> L <br /> In the early 1900s, natural levels of nitrate in ground water were measured in forty-three (43) <br /> L wells throughout the Sacramento Valley by Bryan(1923). It was thought that ground water at <br /> that time was close to"natural" conditions. Based on the work by Bryan, it is estimated that <br /> under"natural"conditions, ground water concentration containing nitrate is no more then about <br /> 13.5 NO3 (3 mg/L-N). Areas having 24.75 mg/L NO3 (5.5 mg/L-N)or more are those in which <br /> L nitrate concentrations may be increasing(Hull, 1984). <br /> 1 DBCP is a nematocide and soil fumigant for vegetables, and grapes. It is thought to cause health <br /> L problems consisting of kidney damage, liver damage, and cancer. The use of DBCP was <br /> discontinued in 1979. The Environmental Protection Agency(EPA) set the maximum <br /> contaminant limit(MCL) at 0.2 parts per billion(ppb)because the EPA believes that given <br /> 6' present technology and resources, this is the lowest level to which water systems can reasonably <br /> be required to remove this contaminant should it occur in drinking water. <br /> 5.0 SOIL PROFILE AND GEOLOGIC INFORMATION <br /> 5.1 Geology <br /> The surface geology at the Site is shown on R. W. Page's(1986)map and is composed of <br /> 6. Miocene to Holocene continental rocks and deposits (Plate 6). According to the map,this unit <br /> consists of"generally poorly sorted clay, silt, sand, and gravel; some beds of claystone, siltstone, <br /> sandstone, and conglomerate." <br /> L <br /> L <br /> L <br /> L <br /> socL <br />