Laserfiche WebLink
<br />Floodplain Boundaries (Post-Project, As Built Shorter Levee) - The post-project floodplain <br />boundaries for the shorter levee that was constructed on the Project were not available in the <br />Corps files. An approximate post-project IOO-year floodplain bOlmdary map was prepared by <br />Board staff using the water surface profile elevation and channel velocity from the March 1977 <br />Corps report at the station for the end of shorter levee shown in the April 1979 construction <br />plans. The 100-year floodplain boundary on the east side of Holly would be at approximate <br />ground elevation 3384.8 feet (MSL) which is estimated to be the westward extension of the <br />backwater as determined by the summation of the energy head of the I DO-year :flood at the end <br />of the shorter levee. This I DO-year floodplain boundary is approximately 600 feet east of the <br />State Highway 89 ramp crossing the levee south of the Town. This 100-year floodplain boundary <br />trends north by northeast intersecting the Holly Ditch leve,: approximately 3500 feet east of the <br />intersection of U.S. Highway 50 and State Highwa.y 89 in the Town of Holly. This approximate <br />. floodplain boundary is outside the corporate limits of the Town of Holly as shown on Figure 13. <br /> <br />Bank protection - Native grasses were considered adequate protection for the design <br />discharge velocities of the Project except for specific sections needing bank protection as <br />discussed in the Project Description section of this Report. The maximum overbank velocity for <br />the design discharge was near 7 feet per second and th,~ average was about 4.5 feet pef second. <br /> <br />Interior Drainage - Both borrow areas have the capacity to store a Standard Project Flood <br />storm volume generated over their contributing drainage areas on the landside of the levee. <br /> <br />PROJECT BENEFITS <br /> <br />The Holly Flood Control Project provides I DO-year flood protection for the Town of Holly <br />including property and residents. <br /> <br />Areas and properties in the IOO-year floodplain prior to construction of the Project were <br />shown on the U.S. Department of Housing and Urban Development (HUD), Federal Insurance <br />Administration (FIA), Flood Hazard Boundary Map of the Town of Holly, (Prowers County), <br />Colorado, dated January 16, 1976. <br /> <br />Completion of the Project in 1981 modified the 100-year :floodplains for Wild Horse <br />Creek and the Arkansas River and excluded the 100-y(:ar flood from the portion of the Town in <br />the 100-year floodplain as shown on the HUD map. As a result the entire corporate limits of the <br />Town were then out of the 100-year floodplain. <br /> <br />The Federal Emergency Management Agency (FEMA), effective May 20, 1983, rescinded <br />the former Flood Hazard Boundary Map for the Town of Holly, Colorado. <br /> <br />POST-PROJECT FLOODED AREAS <br /> <br />The approximate post-project floodplain boundary for the Arkansas River lOO-year flood <br />is shown on Figure 13 prepared by Board staff. An approximate post-project floodplain boundary <br /> <br />10 <br />