Laserfiche WebLink
December 23,2002 <br /> Job Number:LG02492 <br /> Page 4 <br /> V <br /> In the early 1900's,natural levels of nitrate in ground water were measured in forty-three(43) <br /> wells throughout the Sacramento Valley by Bryan.Z It was thought that ground water at that time <br /> was close to "natural" conditions. Based on the work by Bryan, it is estimated that under <br /> "natural" conditions, ground water concentration containing nitrate is no more then about 13.5 <br /> NO3 (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.3 <br /> DBCP was not detected in the water sample. DBCP is a nematocide and soil fumigant for <br /> vegetables, and grapes. It is 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 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 /> `, 4.0 GEOLOGY, SOILS,AND PERCOLATION TEST <br /> The surface geology at the site is shown on a geologic map mapped by Atwater(Plate 6). The <br /> area is mapped as the Pleistocene age Modesto Formation composed of compact silt and very <br /> fine sand.' The geologic map indicates that some areas nearby the site contain eolian or ancient <br /> sand dune deposits. <br /> The surface and near surface soils located at the site are reported to be the Tokay fine sandy loam <br /> 2 Bryan,K., 1923,Geology and ground-water resources of Sacramento Valley of California:U.S. <br /> Geological Survey Water-Supply Paper 495,285p. <br /> v <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,Drin}ang water and health,National Primary Drinking Water Regulations,consumer fact <br /> sheet on: DIBROMOCHLOROPRPOANE. Internet:http://www.epa.gov./OGWDW/dwh/c-soc/dibromoc.htinl <br /> 'Atwater,B.F., 1982,Geologic Maps of the Sacramento-San Joaquin Delta,California:U.S. Geologic <br /> Survey Miscellaneous Field Survey Map MF-1401,Sheet 12,Scale 1:24,000. <br /> OE 430 <br /> Z <br /> '4 <br /> O <br /> ��SOC\ <br />