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F <br /> April 20, 2004 - - <br /> NOA Project Number: E04002A - <br /> ,� Page 6 <br /> 4.3 Potential-Ground Water Contamination`Issues <br /> j Identifying.potential ground-water contamination sources was not part of the scope of work for <br /> the soil suitability study. Potential ground-water contamination can occur from a number of <br /> sources'which often include leaky underground storage tanks, agricultural activities, dairies, <br /> septic systems, storm water infiltration etc. <br /> Any past agricultural activities and the present use of septic systems in the area should be <br /> considered potentiai ground-water contamination sources..-.1t should be noted that three industrial - <br /> waste ponds.are located to the immediate northeast of the Site. <br /> 4:4.Well Water Sample Location <br /> Three water samples were collected from the faucet of the on-site water well on April 13, 2004 <br /> by Abigail Racco of-our office. The location of the well is indicated in Plate.1. <br /> 4.5 Well Water Sample Collection, Handling, and Transportation...: <br /> The samples were collected in a clean plastic container, then decanted into clean;-glass vials: <br /> F1The samples were then transported on ice=and imanediately remanded under chain of custody to <br /> Precision Enviro=Tech, Stockton.-The Chain of Custody document has been included in the <br /> _ appendix of this report. <br /> 4.6 Well Water-Sample Analytical_Results- <br /> F - Nitrate was fou-_at`4:03 mg/L- , well-below the maximum contaminant level set by the <br /> United States Environmental Protection of 45 mg/L=NO- DBCP was not detected in the ` <br /> .. <br /> water sample. The analytical reports prepared by Precision Enviro-Tech can be found in the <br /> F1 appendix of this report. <br /> The presence of nitrates is not uncommon in shallow ground water,aquifers in San Joaquin <br /> County and other parts of the Central Valley __:Nitrate in groundwater 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 /> F1 <br /> In the early 1900s, natural levels of nitrate in ground water were measured in forty-three(43) <br /> 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 /> F, 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 /> nitrate concentrations maybe increasing (Hull, 1984). <br /> ! , _ <br />