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' %.01 September 9,2005 NOA Project Number: E05106B 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,and storm water infiltration. Any past agricultural activities and the present use of septic systems in the area should be considered potential ground-water contamination sources. 4.3 Water Sample Location LOne well permit was found for the subject property address during file review at EHD on August 23,2005.The well permit was under the name Lucchesi for the addess 11573 Norman Avenue and Lwas issued on March 22, 1988. A water sample was taken from the faucet on the residence near the well on August 22,2005 by Ms. Nancy Rosulek(Plate 1). 4.4 Water Sample Constituents J r. The water sample was analyzed for nitrate and DBCP. Nitrate was found at 29.2 mg/L-NO3;below the maximum contaminant level(MCL) set by the US EPA of 45 mg/L-NO3. DBCP was not detected in the water sample. The analytical reports prepared by Precision Enviro-Tech can be found in the appendix of this report. 6. The presence of nitrates is not uncommon in shallow ground water aquifers in San Joaquin County 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. A 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 L concentrations may be increasing(Hull, 1984). 1 `. 1 `. i 5 .444 I L