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December 18,2001 Job Number: LGO1-375 Page 5 The test results indicated that DBCP «,as non-detectable (ND) and nitrate was found at a concentration of 0.598 mg/1-N (2.69 mg/1-NO3). The result of the nitrate test indicates the ground water is below the maximum contaminate level set by the United States Environmental Protection Agency of 10 mg/l as Nitrate N(45 mg/1-NO3) for nitrate. The presence of nitrates and DBCP are 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 1900's, natural levels of nitrate in ground water were measured in forty-three (43) wells throughout the Sacramento Valley by Bryan.' 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 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.' DBCP was not detected in the water sample. DBCP was used as 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 contaminate 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 contaminate - should it occur in drinking water.' '—Bryan,K., 1923,Geology and ground-water resources of Sacramento Valley of California:U.S. Geological Survey Water-Supply Paper 495,285p. 3 Hull,L.C., 1984,Geochemistry of Ground Water in the Sacramento Valley,California: U.S.Geological Survey Professional Paper 1401-B. 4 EPA, 1999,Drinking water and health,National Primary Drinking Water Regulations,consumer fact sheet on:DIBROMOCHLOROPRPOANE. Internet:http://www.epa.gov./OGWDW/dwh/c-soc/dibromoc.html 2pER50 � N > .n Z r o � 1 s f O C\