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j June 13,2005 - :: NOA Project Number: E05042A Though nitrate was not detected in the water sample, the presence of nitrates is not uncommon in shallow ground water aquifers in San Joaquin County and other parts of the Central Valley. Nitrate itYground water occurs as a result of the application of fertilizers,livestock waste, and untreated'- septic ntreated:septic tank waste.'Nitrate is mobile and often accumulates in the shallow ground water zones. In the early 1900s, natural levels of.nitrate in ground water were measured in forty-three (43) wells throughout the Sacramento-Valley by--Bryan (1923). It was thought that ground water at that time was close to "natural' conditions..Based on the work by Bryan,it is estimated that under"natural" conditions,groundwater concentration containing nitrate is no more then about 13.5 mg/L-NO3 (3 { =mg/L-N). Areas having 24.75 /L-NO3;(5.5 mg/L-N) or more are those in which nitrate concentrations may be increasing (Hull, 19$4). DBCP was not found in the sample. DBCP is a nematocide and soil fumigant for vegetables and grapes. "It is thought to cause health problems consisting of kidney damage,liver damage, and cancer. The-'use of DBCP ivas disconti_nized in.1979.-The Environmental Protection Agency (EPA) set the " maximum contaminant limit CL at 0.2 arts per billion b because the EPA believes that given (MCL) p P (ppb) because �. present technology and resources, this'is the lowest level to which water systems can reasonably be required to remove this contaminant should it occur in drinking water. Fi 4.5 Well Water Sample Collection, Handling, and Transportation f The nitrate_ sample was collected in a clean plastic container; the DBCP sample was collected in two. f - clean glass vials:The samples were then transported on ice and remanded under chain of custody to Precision Enviro-Tech, Stockton. _ 4.6..'- Chain ofCustody tl The Chain of Custody document has been included in the appendix of this report. -'" -5.0 SOIL PROFILE AND.GEOLOGIC INFORMATION l . T11e Site is depicted on the Preliminary Geologic Map of the San Francisco - San Jose Cenozoic -_. ;Deposits of the Tracy Quadrangle, California (1991), is within a region of Quaternary Fan deposits. The Unit is composed of gravel, sand silt and clay (Plate 3). fil The surface and near surface soils located at the Site are reported by the San Joaquin Counhy Soil Survey w. to be composed of the-Capay clay, 0-2% slopes, Capay clay,wet, 0-2% slopes, El Solyo, 0-2% slopes and Vernalis clay loam;'0-2% slopes (Plate 4) (USDA,'1992). Table.4 presents some selected, .. _ _ properties of the soils: