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3.0 ENVIRONMENTAL ANALYSIS <br /> 3.1 Geolo¢v and Soils <br /> 3.1.1 Setting <br /> Regional Geology <br /> The project area is situated on the eastern edge of the Great Valley Geomorphic <br /> Province in the Central Valley of California. Adjacent to this province on the west are <br /> the gentle eastern slopes of the Sierra Nevada foothills of the Sierra Nevada Geomorphic <br /> Province. The Central Valley separates the Coast Ranges to the west from the Sierra <br /> Nevada mountain range to the east. This valley is comprised of a thick sequence of <br /> marine and non-marine sediments that range in age from Jurassic to Recent. These <br /> sediments are thickest near the axis of the Central Valley and thin substantially to the <br /> east. <br /> Site Topography and Drainage <br /> Topography at the proposed quarry site is characterized by low lying areas of the <br /> ancient flood plain of the Mokelumne River, with an elevation of about 90 feet above <br /> mean sea level. The surrounding terraces (bluffs) reach elevations approximately 50 feet <br /> higher than this ancient flood plain. Terrace slopes are variable, ranging from about 3:1 <br /> to 10:1 (horizontal to vertical). The Mokelumne River flows east to west between the <br /> proposed quarry site and the processing facility. <br /> Surface drainage from the project area, for the most part, does not flow to the <br /> Mokelumne River. Runoff from the areas both north and south of the Mokelumne <br /> River, is mostly contained on site and is dispersed through evaporation and infiltration; <br /> however, a small amount of runoff may reach the Mokelumne River as sheet flow. <br /> Runoff from the processing facility area north of the river is largely contained by <br /> manmade drainages and ponds. Runoff from the proposed quarry area, is captured by a <br /> manmade drainage ditch that extends along the base of the bluff and terminates at a <br /> small ponded area. Just north of the town of Clements, a drainage pond has been <br /> constructed between the bluff and the proposed quarry site. This pond receives runoff <br /> from part of Mackville Road and Highway 88. Runoff is allowed to infiltrate into the <br /> 18 <br />