Laserfiche WebLink
<br />Access to the dam crest and downstream toe would be provided by constructing <br /> <br />about 1.4 miles of light duty road from State Highway 83 to the right abutment. <br /> <br />Relocations included in the estimate include 0.5 mile of State Highway 83, <br /> <br /> <br />6.3 miles of light duty road, 4.4 miles of transmission lines, and replacement <br /> <br />of State Highway 83 Bridge. <br /> <br />Costs for this alternative vary from about $74.4 million for option Sa to <br />$119.2 million for alternate 5ci. <br /> <br />This alternative has a relatively high construction cost in comparison to <br /> <br />other alternatives and environmental concerns could be significant. If <br /> <br />constructed, Castlewood would be a multiple-purpose dam. Consequently. the cost <br /> <br />allocated to flood control in association with Cherry Creek might be considerably <br /> <br /> <br />less than the total cost developed in Appendix B. <br /> <br />ALTERNATIVE 6 - HARDEN DAM FACE <br /> <br /> <br />This alternative would include protecting the existing embankment crest and <br /> <br />downstream slopes from erosion caused by overflow of the dam during the PMF. <br /> <br />Costs for this alternative have been based on the design shown on plate 37, which <br /> <br />includes a 1. 5 - foot-thick reinforced concrete slab and 2- foot- thick frost blanket <br /> <br /> <br />placed over the entire crest and downstream face of the embankment. The <br /> <br /> <br />hardening would extend about 50 feet past the toe of the dam, and would be keyed <br /> <br /> <br />into the embankment and foundation materials at both the upstream and down-stream <br /> <br /> <br />ends, respectively. A small surface drainage ditch, lined with bedding and <br /> <br /> <br />riprap, would be required downstream from the facing to dispose of the surface <br /> <br /> <br />drainage from the embankment slope. <br /> <br />The entire hardened face of the embankment would be anchored with slab <br /> <br />anchors consisting of rebar grouted in 10-foot deep holes spaced 10 feet apart. <br /> <br />Hydraulic flow computations for this alternative were based on a weir <br /> <br />coefficient of C-2.6 and a length of 14,300 feet. <br /> <br />54 <br />