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IN57 <br /> I MZ <br /> 1,N j MH <br /> k <br /> 3 .0 ENVIRONMENT?,L SETTING <br /> 3 . 1 SOILS <br /> � The site lies in the center of Great Central Valley geomorphic <br /> Province- The valley has been down--warped a ,a filled with <br /> s material eroded from the surrounding mountains since pre- <br /> . <br /> Cretaceous times. As a result, the central part of the valley <br /> Ef is filled with several hundred feet of consolidated and <br /> 4 <br /> unconsolidated sediments. <br /> Ix <br /> Important water-bearing units in the vicinity of Rainbo Bakery <br /> include the Mehrten, Laguna, Tulare, and Victor Formations. <br /> j > The top of the Mehrten ranges from 820 to 1 , 000 ft deep .in the <br /> central Dart of the valley and is about 590 ft thick. The <br /> i nonvolcanic Laguna Formation overlies the andesitic Mehrten on <br /> the eastern side of San Joaquin County as does the' site and <br /> varies from 430 to 1 , 000 ft in thickness. Tha Laguna unit is <br /> a stream-laid unit of discontinuous sand and silt lenses with <br /> clay; <br /> lesser amounts of d, y and gravel. The Laguna sEd5ments <br /> become finer grained toward the center of the basin where the <br /> 1s formation merges with the equivalent west-side formation, the <br /> #� Tulare. The contact is near the San Joaquin River. A th_ck <br /> a <br /> confining layer, the Corcoran clay (usually logged as "blce <br /> clay" by drillers ) , is found near the top of the Tulare <br /> i; <br /> Format;on. The thickness of the clay varies from <br /> approximately 0 ft to 16o €t. <br /> The Victor Formation lies over the Laguna' on the eastern side <br /> oL the county. It varies from 0 to 50 ft thick. The <br /> + : sediments are alluvial fan and interf.an deposits, which are <br /> A_ f <br /> generally coarser than the Laguna Formation. However, the <br /> ` interfan areas contain large amounts of fine sand, silt, and <br /> clay, making the two formations practically indistinguishable. <br /> The aquifer is considered semiconfined because of <br /> I . <br /> discontinuous lenses of clay and silt which create localized <br /> r <br /> 3-1 <br /> r <br />