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<br />upstream side of the dam is riprapped with 18 inches of dumped basalt on a 9-inch <br /> <br />blanket of sand and gravel, The downstream side has been topsoiled and seeded. <br /> <br />An asphaltic concrete road crosses the tap of the dam and connects State Highways <br /> <br />88 and 83 on the right bank to a county road on the left bank. The road is <br /> <br /> <br />federally owned and maintained by Arapahoe County. Armco railings have been <br /> <br />installed on both sides of the road fat the complete length of the dam. <br /> <br />OUTLET WORKS <br /> <br />GENERAL DESCRIPTION <br /> <br /> <br />The outlet works, founded on the Denver Formation, are located in the right <br /> <br /> <br />abutment at embankment station 105+00, and consist of an approach channel, <br /> <br />concrete intake tower with service bridge, a triple barrel concrete conduit, <br /> <br />stilling basin, and a discharge channel. The discharge channel empties into the <br /> <br />Cherry Creek channel a short distance downstream from the dam. The location of <br /> <br />the outlet works is shown on plate 4. A general plan and typical sections are <br /> <br />shown on plate 10. <br /> <br />APPROACH CHANNEL <br /> <br /> <br />The approach channel is approximately 450 feet long, of varying width and <br /> <br />has side slopes of IVan 2H. Concrete approach walls extend 75 feet upstream <br /> <br /> <br />from the intake tower. The bottom of t~e channel between the approach walls is <br /> <br />lined with a I-foot concrete slab on grade for the first 50 feet from the tower. <br /> <br /> <br />The remaining 25 feet is lined with 1.5 feet of riprap on 9 inches of sand and <br /> <br />gravel base. During preparation for che installation of emergency gates in <br /> <br />1983-84, it waS found that 10 to 20 feet.of hard consolidated sediment had been <br /> <br /> <br />deposited within the intake tunnels and upstream of the intake structures. This <br /> <br /> <br />sediment had deposited over the years since permanent impoundment of water behind <br /> <br /> <br />Cherry Creek Pam began in 1956. The deposition of sediments was probably <br /> <br /> <br />aggravated by the fact that regular releases through the outlet works were <br /> <br />nonexistent from 1974 to 1984. The deposited material within the intake tunnels <br /> <br /> <br />and immediately upstream of the trashracks was removed by dredging in 1983-84 at <br /> <br />a cost of $182,400. A flushing scheme has been adopted to keep the intake <br /> <br /> <br />tunnels and emergency gates slots free of accumulated sediments. The intake <br /> <br /> <br />channel and silt deposits are shown on plates 11 and 12. <br /> <br />10 <br />