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f1PI'ENU!K C <br /> REGIONAL HYOROGEOLOGIC SETTING <br /> 9PA gm <br /> Lodi is located in the south-central portion of the Saceranento <br /> Valley. This valley is a broad riorthweet-trending structural trough <br /> bounded on the eatst by the Sierra Nevada and on the west by the <br /> northern Coast Ranges. The valley basement complex is composed of <br /> Paleozoic and Mesozoic metasediments and volcanica as well as <br /> i Jurassic and Cretaceous granitic. rocks. Overlying the basement <br /> complOn is a thick sequence (up to 15.000 feet in the project are0 <br /> i <br /> of sedimentary rocks and unconsolidated sedimenta of Jurassic to <br /> i Recent age. <br /> The unconsolidated sediments are of Pliocene to Recent age and extend <br /> ¢ to depths of up to 4,000 feet in the Lodi area. These sediments <br /> ( consist chiefly of alluvium but in some areas include lacustrine and <br /> marsh or estuarine depasits. <br /> Ground linter <br /> The unconsolidated sediments are the primary fresh-water-bearing <br /> units in the Sacramentp Valley. Ground water occurs in both confined <br /> and unconfined conditions within these sediments. Because both <br /> { confined and unconfined water-bearing sones in much of the valley are <br /> f{ consideeed hydrologically interconnected. occurrence and movement of <br /> ground water within thea are generally not differentiated. ' <br /> While much of the re:gi,•nel water supply cof;as from surface-water <br /> sources, a substantial volume is also dr-vn from the ground-water <br /> table by large irrigation and municipal wells. Proximity to these <br /> uelIs can often determine the local or regional direction of <br /> around-water flow. <br /> A visual survey was conducted within 1/2-mile of the site to identify <br /> nearby wells. The locations of all identified wells are presented on <br /> Figure I. No information an construction or precise usage has yet <br /> been obtained for these wells. Because local high-yield wells exist. <br /> k the local direction of groundwater flow is difficult to estimate but <br /> 13 presumed to parallel regional flow toward the norihusst. <br /> � f <br /> E <br /> f <br /> � 1 Ig1l-13.Lr! <br /> fb ` <br /> i <br />