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<br />1 <br />1 <br />1 <br />I <br /> <br />11 <br /> <br />e <br />t <br />1 <br />t <br />I <br />Mr. Ed Rosar <br />March 21, 1990 <br />Page 2 <br />The conceptual level engineering work has relied on U.S. Geological Survey mapping, scale <br />1 inch = 2000 feet and a contour interval of 20 feet. No soil testing or drilling work has <br />been performed at the sites. We have not evaluated foundation requirements, seepage <br />potential, or sediment loads into the reservoir. Estimated costs are given in 1990 dollars. <br />A 30 percent engineering, legal and construction contingency factor has been included in <br />the cost estimates. <br />USGS flow frequency analysis data for the Colorado River near the Colorado-Utah state <br />line were reviewed; however, no other hydrologic investigations have been conducted as <br />part of this report to determine frequency and availability of flows for diversion. No <br />separate investigations have been completed to determine the probable maximum flood or <br />spillway design flood. Information from a February 1984 report (Wright Water Engineers, <br />Inc., Golden Hill Reservoir Alternate Reservoir Site Study) was utilized to determine that <br />a roller compacted concrete (RCC) dam would appear feasible for purposes of passing the <br />probable maximum flood estimated in the 1984 report. Additional hydrologic and hydraulic <br />studies would be necessary to confirm the adequacy of RCC dams at the East Branch Creek <br />and Adobe Creek sites for passing the probable maximum flood. <br />The location of the two subject reservoirs is shown on Figure 1. The East Branch Reservoir <br />is located in portions of Sections 10, 11, 14, and 15, Range 2 West, Township 2 North of <br />the Ute Principal Meridian of Mesa County, Colorado. The construction costs of the <br />reservoir have been estimated based on roller compacted concrete construction. A <br />description of the East Branch Reservoir project is given in Table 1 and a stage-storage <br />curve is presented in Figure 2. <br />Table 1 <br />East Branch Reservoir <br />Water Surface Elevation <br />Water Surface Area <br />Dam Height <br />Dam Crest Length <br />Dam Embankment Volume <br />Storage Volume <br />1 <br />4,820 feet <br />480 acres <br />100 feet <br />2,700 feet <br />230,000 cubic yards <br />13,700 acre feet <br />