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° October 12,2000 <br /> Job Number:LG00-312 . <br /> { Page 5 <br /> -Sacramento Valley by-Bryan.2 It.was thought"that ground water at that time was close_to <br /> "natural" conditions. =Based on the work by Bryan,.it is estimated that-under"natural".conditions; <br /> ground water concentration containing nitrate is no more then about 3 m N. Areas Navin S.S <br /> ---�- . <br /> mg/L-N or more are those in which nitrate concentrations may be increasing_ <br /> DBCP was not detected in the water sample..DBCP is a nematocide and soil fumi ant for <br /> I� g <br /> vegetables, and grapes. Itis;thought to,cause health problems consisting of kidney damage, fiver. <br /> damage, and cancer. The use of DBCP was discontinued in 1979, The Environmental Protection <br /> Agency PA set the maximum contaminate limit CI: at 0.2 art' r ' <br /> (EPA)) (MCL) parts 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.' <br /> VI. GEOLOGY,SOIL,.'AND PERCOLATION TEST <br /> The geologic literature indicates that�the surficial deposits near the-site are reported to'be <br /> . composed of the Pleistocene age(about 10,000 to 2-nullion years 61d)Modesto Formation <br /> unconformably overlying portions of the olderPliocene age(about 2-million to 5-million years } <br /> old)Laguna Formation(Plate b).s -The Modesto Formation is widespread in the lower elevations'. <br /> ._ of the Central/Sacramento Valleys and-the lower western Sierran foothills. The Modesto <br /> Formation is.generally composed of river alluvium, alluvial,terraces, alluvial fans and abandoned <br /> channel ridg_es.6 The Modesto Formation often consists of tan and-fight-gray gravely sand, silt; <br /> z Bryan,K., 1923,Geology and ground-water resources of Sacramento Valley of California:U.S. <br /> S. i <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 Dninxng Water Regulations,consumer fact <br /> sheet on:DIBROMOCALOROPMANE: Internet:http'//www.epa.gov./OGWDW/dwWc—"Idibmnw,'hlW <br /> 5 Wagner,D.L.,Bortugno,E.J.,and McJunkin,RD., 1990, Geologic Map of the San Francisco-San Jose ' <br /> Quadrangle. California Dement of Conservation,Division of Mines and Geology Map No. 5A(Geology). <br /> Scale 1:250;000. <br /> 6 Helley,E.J.,and Harwood,D-S:,-1985;Geologic:Map of the Cenozoic deposits of the Sacramento <br /> Valley and Northern Sierran Foothills, California. U.S.G.S.Misc.;Field Studies Map MF-1790,.Scale 1:62:500._ <br /> t <br />