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I 60. LMarch 22, 2005 NOA Project Number: E04132A 4.4 Water Sample Location Three water samples were collected from the well head of the domestic water well on January 6, 2005 by Ms. Rebecca Haskett and Mr. Richard Ryan of our office. The locations of the well and water sample are indicated in Plate 1. 4.5 Water Sample Constituents The water sample was analyzed £or nitt'ate and DBCP. Nitrate was found a6;m /L-N ,above ` 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 Lfound 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. LIn 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 groundwater at that time was close to"natural"conditions. Based on the work by Bryan,it is estimated that under"natural" Lconditions,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). 6' DBCP was not detected in the water sample from the on site well. DBCP is a nematocide and soil fumigant for 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. 4.6 Well Water Sample Collection,Handling, and Transportation The samples were collected in a clean plastic container,then decanted into clean,glass vials. The samples were then transported on ice and remanded under chain of custody to Precision Enviro- �' Tech, Stockton. L 4.7 Chain of Custody The Chain of Custody document has been included in the appendix of this report. L 6 L .,44 L