Laserfiche WebLink
hn KLEINFELDER <br /> 3 REGIONAL HYDROGEOLOGY <br /> { The site lies on the west side of California's Central Valley in southwest San Joaquin County. <br /> This region is described by California Department of Water Resources Bulletin No. 146 "San <br /> Joaquin County Ground Water Investigation, July 1967". This paper reports that the Central <br /> Valley is composed of a thick sequence (6,000 feet plume in the middle of the valley) of mostly <br /> marine and, more recently, continentally derived sediments from the Sierra and Coast ranges that <br /> border the valley on the east and west. <br /> Near-surface geology in the Tracy area consists of alluvial fan deposits of recent to late <br /> Pleistocene age derived from the Coast Ranges eight to twelve miles west and south of Tracy. <br /> The deposits appear to be about 100 feet thick under the site as interpreted from a cross-section <br /> of the deposits in Bulletin No. 146. These deposits have moderate to high permeability and the <br /> groundwater is generally unconfined. Lineation of deposition is to the north to northeast. <br /> Beneath the alluvial fan deposits lies the Tulare Formation, composed of continental, <br /> semiconsolidated, discontinuous deposits of clay, silt, and gravel of from 700 to 800 feet <br /> thickness as interpreted from the cross-section in Bulletin 146. A distinctive 100-foot thick, <br /> laterally extensive clay, known at the Corcoran Clay, lies about 300 to 350 feet below the site, <br /> which separates the unconfined acquifers of the upper Tulare Formation from confined aquifers of <br /> the lower Tulare Formation. <br /> i <br /> 24-220176-FO1/CR43-8 (1994) Page 7 of 13 June 3, 1994 <br /> Copyright 1994 Kleinfelder, Inc. <br />