Laserfiche WebLink
July 21,2003 <br /> Job Number:LG03-120 <br /> Page 5 <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 Bryant It was thought that ground water at that time <br /> was close to a"natural"condition. Based on the work by Bryan, it is estimated that under natural <br /> conditions, ground-water concentration of nitrate is no more then about 13.5 NO3 (3 mg/L-N). <br /> Areas having 24.75 mg/L NO3 (5.5 mg/L-N) or more are those in which nitrate concentrations <br /> may be increasing.' <br /> 6.0 GEOLOGY, SOILS, AND PERCOLATION TEST <br /> The surface geology at the site is shown on Pages's4 map and is composed of continental rocks <br /> and deposits, recent to Miocene age (Plate 6). These deposits are composed of a"heterogeneous <br /> mix of generally poorly sorted clay, silt, sand, and gravel; some beds of claystone, siltstone, <br /> sandstone, and conglomerate". <br /> _ The majority of surface soils located at the site are reported to be the Veritas fine sandy loam (no. <br /> 266) located on approximately the east half of the site and the Honcut sandy loam (no. 175) on <br /> the west half of the site(Plate 7)5. The Veritas fine sandy loam is described as a moderately well <br /> drained, nearly level soil on low fan terraces. The Veritas fine sandy loam is deep to a hardpan <br /> and formed in alluvium derived from mixed rock sources. Permeability is moderately rapid in <br /> the Veritas soil. <br /> The Honcut sandy loam is described by the San Joaquin County Soil Survey as a very deep,well <br /> drained,nearly level soil on alluvial fans. The Honcut sandy loam formed in alluvium derived <br /> from granitic rock sources. The permeability is moderately rapid in the Honcut soil. <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 /> 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 Page,R.W., 1986,Geology of the fresh ground-water basin of the Central Valley,California,with texture <br /> maps and sections:U.S.Geologic Survey Professional Paper 1401-C, Scale 1:500,000. <br /> 5 USDA Soil Conservation Service,Soil Survey of San Joaquin County,California,Sheet 25&26. <br /> pERtQ� <br /> Z W <br /> Q � <br /> r <br /> ' 7SS Q�•\ <br />