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January 7,'20 03 <br /> dob'Number: LG02-026 <br /> Page 4 <br /> • "natural" conditions,ground water concentration containing nitrate is no more then about 13.5 <br /> NO,,(3 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.'. . <br /> DBCP was.not detected in the water sample. DBCP is a nematocide and soil fumigant for <br /> vegetables, and 'grapes: Itis thought to cause health problems consisting of kidney damage,'liver <br /> damage, and cancer. The use of DBCP was discontinued in 1979. The Environmental Protection <br /> Agency-(EPA) set the maximum contaminate limit(MCL)'at 0.2,p4rts per billion(ppb) because <br /> the EPA believes that given present technology and resources; this is the lowest level-to which <br /> water systems can reasonably be required to remove this contaminate.should`it occur in drinking . <br /> water.4 . <br /> 4.0 GEOLOGY, SOILS, AND PERCOLATION TESTS <br /> The surficial geology of the site is alluvial.fan deposits derived from the Coast Ranges. These <br /> formation consist of fairly'compact mixtures of gravel, sand, silt and,clay which often four► <br /> heterogeneous and discontinuous layering.. <br /> '--: g - <br /> The San Joaquin County Soil Survey indicates the surface and near surface soils located on the <br /> site consist,of'open pits andgravel excavations (Plate.2).5 Soil properties for this unit are not <br /> presented by the San Joaquin Soil Survey probably,due to the lack of original.top soil in these <br /> areas of excavation. <br /> One shallow (3=ft deep)'and one deep (5-ft deep)percolation.test was performed in the area <br /> adjacent to the existing filter bed leach field.(Plate 1). These two percolation test locations were <br /> separated by about S feet of distance. No ground water was encountered in the borings. The soils <br /> encountered in each boring were.a brown silty sand with gravel to 4 feet in'deptb followed by a <br /> fine clean medium brown sand to a total depth of 5 feet: <br /> 3 Hull,L.C., 1984,Geochemistry of Ground Water in the,Sacramento Valley,Califomia:;U.S. Geological <br /> Survey Professional Paper 1401-B. <br /> EPA, 1999,Drinking water and health',National Primary Drinking Water Regulations,consumer fact <br /> sheet on_DIBROMOCHLOROPRPOANE. Internet:http:l/www;epa.gov./OGWDW/dwh/c-soc/dit5romoc.html <br /> s USDA Soil Conservation Service, 1992,Soil Survey of San Joaquin County,California, Sheet T. <br /> c � , <br /> _ r <br />