Laserfiche WebLink
<br />RECOMMENDATION <br /> <br />Removing the sandbar/island and constructing the dikes all at <br />the same time would provide illUl\edia'te channel capacity with the <br />least long-term Opera.tion and Maint"enance costs. However, the <br />ini tial cost is nearly 2.4 times th,= cost: of building the dikes <br />over a period of years. Simply removing the sediment deposits <br />provides short-term benefits. However, the benefits would decrease <br />substantially over time even with continual maintenance. <br />Therefore, it is recollUl\ended that t:he county pursue either the <br />channel narrowing or the dredqing and channel narrowing <br />alternatives. Building the project in phases (channel narrowing) <br />would be less expensive, both totally and annually; however, the <br />risk of flooding during the construction period would remain high. <br />If the county does not wish to accept this risk then, dredging and <br />channel narrowing would be the rec01ffiuended plan. <br /> <br />ADDITIONAL DATA COLLEC:TION AND ANAL"\!'llIB <br /> <br />The <br />completed <br /> <br />following design and analysis activities <br />before any proj ect is const:ructed. <br /> <br />should <br /> <br />be <br /> <br />Flood Plain Analvsis. The impac1:s of 'I:he project on the flood <br />plain/floodway should be determined to emsure that the project does <br />not negatively impact water surface elevat:ions upstream from the <br />bridge. <br /> <br />Sediment Transport Anal vsis. A sediment transport model <br />should be developed to determine the locat:ions of sediment scour <br />and deposition both upstream and downstream from the bridge. This <br />is especially important due to the irrigations diversion along the <br />reach. Any changes in the sedimen1: deposition patterns may cause <br />water supply problems for irrigators. <br /> <br />The above two i te,ms can be combined in ei ther a 1- or 2- <br />dimensional computer modeling process. <br /> <br />Detailed Desiqn Lavout. The designs should be layed out in <br />detail so that construction crews/cont:ractors can easily locate the <br />work in the field. This work item is necessary to describe in more <br />de'tail the exact location of the work t:o be done. <br /> <br />Section 22 - South Platte River, Merino, Colorado <br /> <br />Page 7 <br />