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November 27, 2006 <br /> NOA Project Number. E06115A <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 /> mg/IN). 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 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 nitrate sample was collected in a sterile plastic container,the DBCP sample was collected in two <br /> sterile glass vials. The samples were then transported on ice and remained under chain of custody to 5, <br /> FGL Environmental, Stockton. <br /> L <br /> - 4.6 Chain of Custody <br /> G <br /> The Chain of Custody document has been included in the appendix of this report. <br /> L <br /> L <br /> L <br /> L <br /> L <br /> L <br /> L <br /> 6 <br /> L <br /> L <br />