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Nti./ S../ <br /> ` March 28,2005 <br /> NOA Project Number: E05007B <br /> 4.2 Potential Ground Water Contamination Issues <br /> Identifying potential ground-water contamination sources was not part of the scope of work for the <br /> soil suitability study. A Surface and Subsurface Contamination Report will address this issue. Please <br /> .. refer to this report for descriptions. <br /> Potential ground-water contamination can occur from a number of sources which often include <br /> leaky underground storage tanks, agricultural activities,dairies, septic systems, and storm water <br /> infiltration. Any past agricultural activities and the present use of septic systems in the area should <br /> be considered potential ground-water contamination sources. <br /> 4.3 Water Sample Location <br /> ` No permits were found during EHD file review on January 28,2005, for the subject property <br /> address of 30850 South Highway 33. <br /> ` A water sample was taken from the pipe manifold near the well head in the middle of the property <br /> on March 1,2005 (Plate 1). <br /> ` 4.4 Water Sample Constituents <br /> The water sample was analyzed for nitrate and DBCP. Nitrate was found at 45.4 mg/L-NO3, <br /> ion slightly above the maximum contaminant level (MCL) set by the US EPA of 45 mg/L-NO3. DBCP <br /> was not detected in the water sample. The analytical reports prepared by Precision Enviro-Tech can <br /> be found in the appendix of this report. <br /> am <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 /> 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 /> concentrations may be increasing (Hull, 1984). <br /> 5 <br />