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L September 30,2002 Job Number:LG02-335 Page 4 The depth to ground water below the site was approximately 22 to 25 feet between Fall 1998 and Spring 1999 (see Plates 2 and 3). The ground water flow direction was toward the ` north with a gradient ranging between 3.3 to 3.8 feet per mile(see Plates 4 and 5). A ground-water sample was obtained from the onsite water well on September 25, 2002 ` by a representative of our company. The samples were sent to Precision Environmental Laboratory, Stockton,for testing on the same day. The samples were tested for the presence of dibromochloropropane(DBCP) and Nitrate (NO3)per County requirements. test results indicated that IRB P wac non-detectable (NDl and nitrate was found at 39 mg/1-N 3(or 8.6 mg/L-N). 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 45 mg/L as NO3 (or 10mg/L-N). The test results are attached in the appendix. 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 a"natural"condition. Based on the work by Bryan,it is estimated that under ` natural conditions, ground-water concentration of 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 way r�twrtPd in the water sample. 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 contaminate limit (MCL)at 0.2 parts per billion (ppb)because the EPA believes that given present technology and resources,this is the lowest ` '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. 'pf f jOy A