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L <br /> LFebruary 8,2007 <br /> NOA Project Number: E06161A <br /> fertilizers,livestock waste, and untreated septic tank waste. Nitrate is mobile and often accumulates <br /> in the shallow ground water zones. <br /> L 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/L-N). Areas having 24.75 mg/L-NO3 (5.5 mg/L-N) or more are those in which nitrate <br /> Lconcentrations may be increasing(Hull, 1984). <br /> DBCP was not detected in the water sample. DBCP is a nematocide and soil fumigant for <br /> L 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 /> L 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 /> r <br /> The sample for nitrate was collected in a sterile plastic container, the sample for DBCP was <br /> L collected in two sterile glass vials. The samples were then transported on ice and remained under <br /> chain of custody to FGL-Environmental, Stockton. <br /> 4.6 Chain of Custody <br /> The Chain of Custody document has been included in the appendix of this report. <br /> L <br /> 5.0 SOIL PROFILE AND GEOLOGIC INFORMATION <br /> LThe Site is depicted on the Geologic Maps of the Sacramento-San Joaquin Delta as within the <br /> L Quaternary Modesto Formation and Quaternary Riverbank Formation (Plate 7). The Quaternary <br /> Modesto Formation (undifferentiated) is unit of undifferentiated alluvial deposits,mainly arkosic, <br /> forming the toe of the Mokelumne alluvial fan,generally covered by 0.3 to 1.0 m of Holocene <br /> intertidal deposits. <br /> L The surface and near surface soils located at the Site are reported by the Sax Joaquin County Soil Survey <br /> to be composed of Piper sandy loam and Shinkee muck,both 0-2% slopes (Plate 8) (USDA, 1992). <br /> LTable 1 presents some selected properties of these soils: <br /> L <br /> 5 <br /> "44 <br /> L <br />