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HomeMy WebLinkAbout[Untitled]_2-58Mr. Yam Haing 2612 Buck Owens Blvd LLC January 25, 2013 - Page 2 BACKGROUND TOPOGRAPHY The site is located at an elevation of 400 feet above MSL, and the topography slopes slightly to the southwest. The subject site is located within the San Joaquin Valley, approximately 15 miles west of the Sierra Nevada, 30 miles east of the Temblor Range, and 30 miles north of the San Egmidio Range. GEOLOGY The subject site is located on the eastern flank of the San Joaquin Valley and west of the southern Sierra Nevada. The surface of the San Joaquin Valley is composed primarily of unconsolidated Pleistocene (1.6 million to 11,000 years ago) and Recent (11,000 years ago to the present) alluvial sediments. Beneath the alluvial sediments are older, predominantly lake -bed deposits. These lie unconformably on Mio- Pliocene marine sediments, which extend to a crystalline basement at a depth of approximately 20,000 feet below grade (fbg). At the subject site, surface deposits consist of Quaternary (recent) unconsolidated alluvium overlying Quaternary (Pleistocene) nonmarine sediments. Geologic deposits in the study area include Pleistocene alluvial sediments that form a homocline dipping gently to the west - southwest. The deposits are alluvium consisting of indurated and dissected fan deposits (California Division of Mines and Geology, 1965, Geologic Map of California, Bakersfield Sheet). Surface soils are classified by the Soils Conservation Services as Kimberlina - Urban Land - Cajon Complex and are characterized as 35 percent Kimberlina fine, sandy loam with moderate permeability; 30 percent Urban land with impervious surfaces and altered fills; and 20 percent Cajon loamy sand with high permeability. In the region of the site, the Tertiary sedimentary sequence from top to bottom is nonmarine Kern River Formation, nonmarine Chanac Formation, marine Santa Margarita Formation (possibly interfingering with Chanac Formation due to tentative correlation of type Santa Margarita Formation west of the San Andreas Fault), marine Round Mountain Silt, marine Olcese Sand, marine Freeman Silt, marine Jewett Sand and Pyramid. Hill member, marine Vedder Sand, nonmarine Walker Formation. Of these, only the Kern River, Chanac, and Santa Margarita formations are important to the hydrogeology of the site. The Tertiary, nonmarine Kern River Formation is unconformably overlain by bouldery terrace deposits of Quaternary Older Alluvium. Two naturally occurring geologic units are present in the near surface at the site. The two natural units are the Tertiary (Miocene to Pliocene), nonmarine Kern River Formation and Quaternary (Pleistocene) Older Alluvium. The Older Alluvium forms a thin terrace deposit lying unconformably on the Kern River Formation.