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June 10,2002 <br /> Job Number: LG02-164 <br /> Page 5 <br /> The test results indicated that DBCP was non-detectable (ND) and nitrate was found at <br /> 5.6 mg/1-NO3 (or 1.2 mg/L-N). The result of the nitrate test indicates the ground water is below <br /> the maximum contaminate level set by the United States Environmental Protection Agency of 45 <br /> mg/L as NO3 (or l Omg/L-N). <br /> The presence of nitrates and DBCP are not uncommon in shallow ground-water aquifers <br /> in San Joaquin County and other parts of the Central Valley. Nitrate in ground water occurs as a <br /> result of the application of fertilizers, livestock waste, and untreated septic tank waste. Nitrate is <br /> mobile and often accumulates in the shallow ground-water zones. <br /> In the early 1900's, natural levels of nitrate in ground water were measured in forty-three <br /> (43)wells throughout the Sacramento Valley by Bryan.' It was thought that ground water at that <br /> time was close to a"natural"condition. Based on the work by Bryan, it is estimated that under <br /> natural conditions, ground-water concentration of nitrate is no more then about 13.5 NO3 (3 <br /> mg/L-N). Areas having 24.75 mg/L NO3 (5.5 mg/L-N) or more are those in which nitrate <br /> concentrations may be increasing.3 <br /> DBCP was not detected in the water sample. DBCP is a nematocide and soil fumigant <br /> for vegetables, and grapes. It is thought to cause health problems consisting of kidney damage, <br /> liver damage, and cancer. The use of DBCP was discontinued in 1979. The Environmental <br /> Protection Agency(EPA) set the maximum contaminate limit(MCL) at 0.2 parts per billion <br /> (ppb) because the EPA believes that given present technology and resources, this is the lowest <br /> level to which water systems can reasonably be required to remove this contaminate should it <br /> occur in drinking water.' <br /> ' Bryan,K., 1923,Geology and ground-water resources of Sacramento Valley of California: U.S. <br /> Geological Survey Water-Supply Paper 495,285p. <br /> 3 Hull,L.C., 1984,Geochemistry of Ground Water in the Sacramento Valley,California:U.S.Geological <br /> Survey Professional Paper 1401-B. <br /> 4 EPA, 1999,Drinking water and health,National Primary Drinking Water Regulations,consumer fact <br /> sheet on:DIBROMOCHLOROPRPOANE. Internet:http://www.epa.gov./OGWDW/dwh/c-soc/dibromoc.htrnl <br /> pER3 N <br /> 1 h <br /> Z � <br /> O � <br /> r <br /> ♦sS O G� <br />