A planning-level study was conducted for the City of Cheyenne to assess flooding potential and develop alternative plans to prevent such flooding. Hydrologic modeling was performed, with 2- year though 100-year flood discharges developed along primary drainage ways. Hydraulic analyses were conducted using the flood discharge estimates, survey data, contour mapping, and the HEC-2 computer backwater model to determine water surface profiles and floodplain
limits. Flooded areas were judged for both life-safety hazards and property-damage hazards. Alternative flood control plans were developed which included: detention ponds, storm sewer systems, drainage channels, and structure flood proofing. Cost estimates were made for each plan alternative. To compare the benefits to be derived from each alternative with the alternative's cost, preliminary cost estimates were made for each alternative. Through the use of a screening process, which incorporated the economic evaluation and other non-economic criteria, final plan alternatives for each drainage reach were selected.
