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grate of the same diameter. Intake water will also run under the eave of the trashrack if the top is <br />completely blocked by trash. <br />5.1.2 Cast Iron Slide Gate <br />The cast iron slide gate assembly includes a 12-inch diameter flange back frame with sliding disc and <br />a lifting stem. The gate was designed for a seating head of 50 feet of water pressure based on the <br />elevation of the existing 12-inch intake CIP. <br />The. slide gate is mounted at an angle to allow the stem to be installed along the side slope of the <br />reservoir. The stem is encased in anoil-filled pipe to prevent freezing, thus allowing operation of the <br />gate during the winter. The stem and casing assembly is supported at approximately 8-foot intervals <br />with piers that penetrate the full depth of the upstream clay blanket. <br />~ 5.1.3 Operator's Platform <br />The operator's platform is located at the crest of the dam facing upstream. The bottom slab of the <br />' platform is approximately 8 feet square and 12 inches thick. On the top of the footing is a 4-foot- <br />high, three-sided enclosure. The walls of the enclosure are 12 inches thick. The open side of the <br />' enclosure is next to the dirt track that runs along the dam crest. All structural elements for this <br />platform are reinforced concrete. The slab has a 1% slope from the far end of the slab down to the <br />i dirt track side for drainage purpose. <br />The operator's platform houses the valve operator. The operator consists of a geared hand crank <br />mounted on a pedestal. The hand crank is removable so that there is no way to operate the gate <br />without it. The rising stem is covered by a clear stem cover to keep the threads clean for easy <br />operation. A port for filling the stem casing with oil is also accessed in the operator's platform. <br />5.2 Outlet Works Analysis and Design <br />The overall arrangement of the low-level outlet works is shown in the plans in "Construction <br />Drawings for Monument Dam Preventive Measures" (Barr, 2007). It consists of a new intake <br />structure to be constructed over the entrance to the existing 12-inch cast-iron pipe. The cast-iron pipe <br />extends a distance of approximately 300 feet to a new outlet drop structure to be constructed where <br />the existing cast-iron pipe outfalls. The drop structure consists of an 8-foot-diameter concrete <br />manhole. The outlet of the drop structure is a 24-inch reinforced concrete pipe extending at a 1% <br />grade for approximately 220 feet through the additional fill being placed at the toe of the dam. The <br />outlet of the 24-inch reinforced concrete pipe discharges into a riprapped plunge pool. The existing <br />300-foot-long, 12-inch-diameter cast-iron pipe also includes a valve box and manhole extending to <br />the surface of the dam located approximately 50 feet upstream of the outlet of the pipe. The valve <br />will be removed from the pipe and a pipe spool will be installed in its place using coupling clamps. <br />The valve structure will be abandoned. Abandonment will consist of filling the invert of the <br />structure with concrete to a level above the pipe and filling the remainder of the structure with sand. <br />P:\Mpls\06 CO\26\0626067\WorkFiles\DesignReport\FINAL\DesignReportFINAL.doc 8 <br />