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_ April 7, 2006 NOA Project Number: E06020A 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. Please see section 4.4 for additional water quality details. 4.3 Water Sample Location According to the owner,one we4 xists on the property. 'One well permit was found that was issued to the present owner on Mar 1, 2001. The permit was for the installation of a domestic well drilled to an approximate depth of 440 feet with a grout seal depth of 100 feet.Another permit was issued ` on January 23, 2003 for the installation of a new pump at the same address. A water sample was taken by Mr. Colin Stock on March 16, 2006 from the spigot of the well on the property. ` 4.4 Water Sample Constituents The water sample was analyzed for nitrate and DBCP. The analytical reports prepared by FGL Environmental can be found in the appendix of this report. Nitrate was detected in the water sample at a level ' cif 4.8 mg -NO3. This level is far J elow the maximum contaminant level (MCL) set by the US EPA for nitrate which is 45 mg/L'-NO3. DBCP 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 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). BCP was not detected in the water sample. The Environmental Protection Agency (EPA) set the ma�umcon�tarninant limit (MCL) for DBCP at 0.2 parts per billion (ppb) because the EPAiben present technology and resources, this is the lowest level to which water systems 5 6. .444 ■r