Laserfiche WebLink
<br />remain exposed to the flood hazard. Flood plain zoning was also <br />considered but found to be impractical. Flood proofing would <br />provide some protection under existing conditions and added <br />protection under future conditions of economic development. <br />It would not, however, be a complete solution to the flood <br />problem. Methods of flood damage reduction, other than posi- <br />tive measures of flood volume reduction, would be excessively <br />costly in terms of residual flood damages and constraints on <br />the optimum use of the larger flood plains. The economic costs <br />of suddenly modifying existing patterns of community growth <br />would be substantial. Established public facilities, parti- <br />cularly traffic systems, would not be used to the extent <br />planned. Private investments, committed on the basis of extend- <br />ing growth patterns, would be subject to economic losses. Since <br />nonstructural methods of flood damage reduction were not an <br />acceptable solution to the problem, the formulation process was <br />directed to structural measures. <br /> <br />(2) Structural measures. <br /> <br />(a) Levees. Floods in the Sand Creek basin are <br />characterized by a short duration and by high peak discharges. <br />Valley slopes are steep. High levees would be required and <br />vertical restrictions would be imposed by railroad, highway, <br />road, and by the Stapleton Interna1;ional Airport runway clear- <br />ances, thereby requiring extensive relocations. The construc- <br />tion of levees along Sand and Toll Gate Creeks is estimated to <br />cost in excess of $20 million. In view of these considerations, <br />levees were found to be a costly and an economically inefficient <br />means of flood control in the Sand Creek basin. <br /> <br />(b) Channel improvements. Channel improvements <br />providing protection against floods ranging from a 4-percent <br />chance of annual occurrence through standard project flood <br />occurrence were analyzed. This analysis indicated that a feas- <br />ible project, providing protection against a flood having a l- <br />percent chance of annual occurrence, could be provided. The <br />larger channels required to pass higher design discharges were <br />not found to be economically justified due to high relocation <br />costs of development along channel alignments. In addition, <br />channel improvements alone would not reduce the potential flood <br />damage along the South Platte River downstream from Denver. <br />Potential cqannel improvement projects on Sand Creek and Toll <br />Gate Creek were selected for detailed study and analysis. <br /> <br />(c) Diversion. Suitable diversion routes are <br />not available in the Sand Creek basin. <br /> <br />49 <br />