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6. <br /> March 15,2007 <br /> NOA Project Number. E07031A <br /> 4.4 Water Sample Constituents <br /> r The water sample was analyzed for nitrate and DBCP. Nitrate was foun J <br /> t 7.9 mg L-NO�ow <br /> the maximum contaminant level (MCL) set by the US EPA of 45 mg/L-N 3. was not <br /> detected in the water sample. The analytical reports prepared by FGL Environmen can a found <br /> �. in the appendix of this report <br /> The presence of nitrates is not uncommon in shallow ground water aquifers in San Joaquin County <br /> and other parts of the Central Valley. Nitrate in ground water occurs as a result of the application <br /> of fertilizers,livestock waste,and untreated septic tank waste. Nitrate is mobile and often <br /> accumulates in the shallow ground water zones. <br /> r <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 /> 1. 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 /> L. concentrations may be increasing (Hull, 1984). <br /> 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 /> damage, 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 <br /> The water sample for Nitrate was collected in a sterile plastic container,and the sample for DBCP <br /> was collected in two sterile glass vials. The samples were then transported on ice and remained <br /> under chain of custody to FGL Environmental,Stockton. <br /> 4.6 Chain of Custody <br /> The Chain of Custody documents have been included in the appendix of this report. <br /> 5.0 SOIL PROFILE AND GEOLOGIC INFORMATION <br /> The Site is depicted on the Geologic Map of the San Francisco -San JoseQuadrangle,as within a region of <br /> Quaternary Modesto Formation. Quaternary Modesto Formation is a unit of arkosic alluvium <br /> ` forming Mokelumne River terraces and alluvial fan; chiefly sand with minor gravel and silt;probably <br /> glacial outwash (Plate 7). <br /> 5 <br /> r <br />