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<br />I <br /> <br />O~1776 <br /> <br />- 33 - <br /> <br />I <br /> <br />I <br /> <br />I <br /> <br />The emergency spillway design hydrograph, when routed through <br />structures L-l, L-2 and L-3, will cause less than one foot flow <br />depth through the spillway, The structures will pass a l5-inch <br />six-hour duration, point rainfall centered over the area above each <br />structure (10.2 inches runoff) without overtopping the embankment. <br />The spillway size was determined by routing the freeboard hydrograph <br />through the structures. This determined the need of an emergency <br />spillway bottom width of 370 feet for L-l, 135 feet for L-2, and <br />132 feet for L-3 structure. <br /> <br />II <br /> <br />I <br /> <br />Engineering Design <br /> <br />I <br /> <br />Field investigations to determine structural measure needs <br />,,,ere conducted on the entire Limon Hatershed, These investigations <br />resulted in the selection of three sites, L-l, L-2, and L-3, for <br />flood;mter-retarding storage, Sites L-l, L-2, and L-3 are located <br />on the West, Biddle, and East drainages respectively above the Town <br />of Limon as sho,-m on Project Hap. <br /> <br />I <br /> <br />I <br /> <br />With these structures in place, the existing channels through <br />the Town of Limon will be adequate to carry the principal spilhmy <br />releases and the flood flows from the unreservoired areas. Factors <br />included in the selection cf three structure sites included: (1) <br />maximum control of floodwater, (2) topography, (3) site conditions, <br />and (4) existing facilities including the golf course and proposed <br />Interstate Highway No, 70, <br /> <br />I <br /> <br />I <br /> <br />Detailed topographic maps of the dam sites and pool areas <br />were obtained by planet able surveys on all three of the proposed <br />floodwater-retarding structures. <br /> <br /> <br />A geologic inspection was made on all three proposed dam <br />sites. A preliminary geologic investigation was made on proposed <br />dam site L-l and is considered adequate for work plan design on all <br />three proposed structures. <br /> <br />I <br /> <br />Embankment slopes of 3 1/2:1 upstreillO and 2 1/2:1 <br />were used for embankment estimates on all three sites. <br />purpose of planning design, drains were included under <br />section of the respective dams. In the final analysis <br />may not be necessary to include these drains. <br /> <br />downstream <br />For the <br />the do,mstrearn <br />and design, it <br /> <br />I <br /> <br />I <br />I <br />