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SITE HISTORY <br /> An historic literature review was performed to establish the <br /> development history of the site. Aerial photos taken between <br /> 1963 and 1975 indicate that the project site consisted of vacant <br /> land with trees and what appears to be a residence located south <br /> of the site. The properties to the north of the site appear to <br /> have had industrial shops present since at least 1963. The <br /> Kearney-KPF facility (plating, galvanizing, and electric <br /> switching manufacturing) has been in operation since 1951. The <br /> 1963 aerial photographs revealed that the Al Kramp facility was <br /> in existence at that time. <br /> REGIONAL GEOLOGY AND HYDROGEOLOGY <br /> The project site is located in the Delta subregion of the Central <br /> Valley physiographic region of California. The Central Valley is <br /> a topographic depression bounded on the west by the Coast Ranges <br /> and on the east by the Sierra Nevada geomorphic provinces. The <br /> Delta subregion is characterized by alluvial plains and fans, <br /> river flood plains and channels, and dissected uplands. The <br /> project site is situated on alluvial deposits consisting of <br /> interbedded, unconsolidated and semi-consolidated gravel, sand, <br /> silt and clay. <br /> Groundwater occurs in the project area in shallow, unconfined and <br /> semi-confined aquifers and in deep confined aquifers. The water <br /> elevation of the shallow water table fluctuates with rate of use <br /> and recharge. Recharge to the shallow zone occurs by infiltra- <br /> tion of precipitation and local irrigation waters. The deeper <br /> aquifers are comprised of well sorted, permeable sand and gravel <br /> units and are confined by overlying silt and clay deposits. The <br /> deeper water bearing zones are located at depths in excess of <br /> 100 feet below the ground surface. Recharge to these aquifers <br /> is by lateral subsurface groundwater flow and by some leakage <br /> through the upper confining clay layers. Local groundwater, <br /> obtained from the deep aquifer, is primarily used for industrial <br /> and irrigation supplies and domestic use. <br /> Hydrogeologic assessment investigations performed in the vicinity <br /> of the project site (Kearney-KPF) indicate that the shallow <br /> aquifer has had variable flow directions, likely as a result of <br /> local well pumping. The assessment documents indicate that the <br /> groundwater gradient during the late 1970 ' s was towards the <br /> south-southeast with the flow direction changing to the northeast <br /> direction throughout the 1980 ' s. <br /> 2 - BSI <br />