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P. February 22, 2006 NOA Project Number: E06010A /4.3 Water Sample Location One well permit was found for the Site address of 11715 North Clements Road during file review at EHD on February 14, 2006. The permit is dated October 5, 2005, and is for a new domestic well. The location of this well was confirmed during the field work for this study; one irrigation well was also observed. The locations of the wells are indicated on Plate 1. - ✓At the request of the client, one water sample was collected from each well on February 10, 2006. The sample at the domestic well was collected from a spigot at the well head. The sample at the irrigation well was collected from the water flowing through an open concrete pipe located close to ri the well head. The locations of the samples are depicted on Plate 1. 4.4 Water Sample Constituents The water samples were analyzed for nitrate and DBCP. Nitrate was found at 2.5 mgZ - domestic well and 3. m�&-NO, in h,�ig�ll,well below the maximum contaminant level , (MCL) set by the US EPA of 45 mg/L-NO3. The analytical reports prepared by FGL Environmental of Stockton, California can be found in the appendix of this report. 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 F4 concentrations may be increasing (Hull, 1984). DBCP was not detected in either water sample. DBCP is a nematocide and soil fumigant for P vegetables and grapes. It is thought to cause health problems consisting of kidney damage, liver damage, and cancer. The use of DBCP was discontinued in 1979. The Environmental Protection Agency (EPA) set the maximum contaminant limit (MCL) at 0.2 parts per billion (ppb) because the EPA believes that given present technology and resources, this is the lowest level to which water systems can reasonably be required to remove this contaminant should it occur in drinking water. f_3 II �€ 6 4