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F-1, 3 I March 3 2005 NOA Project Number: E04155A � Y According to these maps (Plates 3-6),ground water lies between 130 and 150 feet below ground surface and flows at a gradient of about 5 feet per mile to the northwest in the vicinity of the Site. i A thin zone of perched ground water (above the hardpan layer) was encountered at a depth of three feet by the staff of Neil O. Anderson&Associates, Inc. during the drilling of two percolation test II .. holes to a depth of 25 feet on February 7, 2005. y/4.2 Potential Ground Water Contamination Issues Identifying potential ground-water contamination sources was not part of the scope of work for the soil suitability study. Potential ground-water contamination can occur from a number of sources which often include leaky underground storage tanks, agricultural activities, dairies, septic systems, Ftand storm water infiltration. Agricultural activities and the use of septic systems in the area should be considered potential ground-water contamination sources. , 3 4.3 Water Sample Location No permits were found for the subject property address of 16100 E Harney Lane during review on January 6, 2005. A water sample was taken from the 12il2e manifold properi�=,n'1aty 1� on February 10, 2005. /4.4 Water Sample Constituents F The water sample was analyzed for nitrate and DBCP. Nitrate was found at(C4m -NO3i below the maximum c an evel_(MCL) set.by the_US EPA of 45 mg/L-NO3tiDBCP was detected in the water sam le .9 Labove�the � he analytical reports prepared `J by Precision Enviro-Tech can be found in the appendix of this report. presence resence of nitrates is not uncommon in shallow ground water aquifers in San Joaquin County a � and other parts of the Central Valley. Nitrate in ground water occurs as a result of the application of fertilizers,livestock waste, and untreated 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, ground water concentration containing nitrate is no more then about 13.5 mg/L-NO3 (3 mg/L-N). Areas having 24.75 mg/L-NO3 (5.5 mg/L-N) or more are those in which nitrate ` concentrations may be increasing (Hull, 1984). 5 f i