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<br />Dolores River <br /> <br />. A riprap(filter blanket 24 inches thick with adequate toe <br />protection against erosive velocities. <br /> <br />. Tie-ins to high ground at the upstream and downstream ends. <br /> <br />. Dust control measures during construction and seeding of the <br />lands ide slope to prevent erosion following construction. <br /> <br />Item <br /> <br />100-Year <br />Protection <br />Project <br /> <br />Excavation (stripping, inspection, <br />& toe trenches - cubic yards) <br />Embankment Material (cubic yards) <br />stone Protection (riprap - in tons) <br />Concrete (for floodwall - in cubic yards) <br />Seeding & Dust Control (acres) <br />Stabilized Aggregate Road Base (tons) <br /> <br />24,000 <br />35,000 <br />13,600 <br />60 <br />2 <br />3,200 <br /> <br />Based on unit costs developed by the corps for other recent <br />projects in western Colorado, the total project cost estimate for <br />100-year protection would be approximately $1.1 million. These <br />estimates used a 25 percent contingency and included the cost for <br />interior drainage control. It is assumed for this estimate that <br />12 percent of the subtotal would suffice for preconstruction <br />engineering and design and 8 percent for construction management. <br />The estimates did not include any real estate costs, which could <br />be sizeable. The Colorado Water Conservation Board indicated <br />that for purposes of this report, the assumption should be made <br />that all necessary easements are in place. The project cost <br />could be somewhat less if a substantial amount of the existing <br />earth mound materials are determined to be suitable for reuse. <br /> <br />SUMMARY AND CONCLUSIONS <br /> <br />. The expected water-surface profile for the 100-year flood <br />event is nearly identical to that developed for the Corps Flood <br />Hazard Information Report in 1978 and later adopted by FEMA in <br />1989 for the flood insurance study. <br /> <br />. The existing earthen mounds should not be considered <br />adequate to raise given their present condition (at least not <br />without a detailed geotechnical investigation). <br /> <br />14 <br />