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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />II <br />I <br /> <br />The lower site is suspected of being on an old lands ide which would <br />probably make foundation preparations difficult and expensive. The <br />Upper Beaver Creek site is probably a good RCC site from a geologic <br />and geotechnical viewpoint. RCC dams were laid out there using the <br />same reservoir volumes as those assumed for the earthen dams. <br /> <br />4. Flood Hydrology and Spillway Layouts <br /> <br />The spillway design floods for both the upper and lower <br />Beaver Creek sites were developed using the standard methods described <br />in Section IV, A, 4, Hydrologic and Hydraulic Criteria. The peak <br />inflows from the design floods are low relative to the other dams <br />studied because of the small drainage areas. Lower Beaver has a rela- <br />tively cheap spillway because its drainage area for flood purposes is <br />3.8 mi2 yet it captures water from 11.7 mi2 by using a diversion and <br />feeder canal. The inflow design floods are summarized as follows: <br /> <br />DRAINAGE AREA <br /> <br />PEAK INFLOWS <br /> <br />Lower Beaver <br />Upper Beaver <br /> <br />3.8 mi2 <br />2.4 mi2 <br /> <br />2100 cfs <br />1330 cf s <br /> <br />The spillway inflow design floods were routed through the <br />reservoirs using the criteria described earlier. This resulted in <br />required spillway widths which varied from 70 ft for the small dam on <br />Lower Beaver Creek to 45 ft for the large dam on Upper Beaver Creek. <br />Channel alignments and quantity estimates were made for each of the <br />spillways. For the RCC dams a 65 ft wide crest width was assumed for <br />all dams; the channel is slightly longer for the larger dams. <br /> <br />5. Outlet Works Design <br /> <br />I <br />I <br />I <br />I <br />I <br /> <br />The outlet works were designed in accordance with the cri- <br />teria described in Section IV, A, 4. For the Beaver Creek Dams this <br />resulted in the use of the minimum pipe diameter. The design selected <br />includes a 24 inch diameter reinforced concrete pipe through the dam. <br />Flow control is provided by an hydraulically operated sluice ga te on <br />the upstream side wi th hydraulic operator controls on the dam crest. <br />The downstream end of the conduit includes a standard USBR impact type <br />stilling basin. <br /> <br />IV"'28 <br />