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Final Environmental Assessment for Stormwater Drainage Project on F. E. Warren Air Force Base, Wyoming

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Intense storms and large floods are natural events for the Cheyenne area. The most devastating flood on record occurred on 1 August 1985 Appendix A, Figure 1 taking 12 lives and causing over 60 million in property damage. The inadequacy of the local drainage system was obvious during the 1985 flood, and much of this inadequacy remains today City of Cheyenne 2005. Francis E. Warren Air Force Base F. E. Warren AFB has experienced flooding many times in the past. It is estimated that in the past century, the local area has experienced five major storm events. F. E. Warren AFB is located upstream from the city of Cheyenne and, via the current drainage patterns, water accumulates on base and is funneled through the main gate along Randall Avenue into the downtown Historic District of Cheyenne. During a major storm event, over 1,100 cubic feet per second cfs of stormwater can be channeled into the city. During the 1985 flood, the flow downtown where the damage was most severe reached 2,000 cfs therefore, the flow contribution from base drainage is significant Balloffet-Entranco 2001. Floods are classified according to their frequency and depth. For instance, there are 10-year, 25-year, 50- year, 100-year, and 500-year floods. A 100-year flood occurs less frequently than a 10-year flood, but because a 100-year flood carries more volume and depth of water, it is far more destructive and presents a more serious threat to human safety CCRFCD 2005. A 100-year flood has a 1 chance of occurring in any given year. A major component of the proposed action is the construction of detention basins.

Subject Categories:

  • Hydrology, Limnology and Potamology
  • Logistics, Military Facilities and Supplies
  • Water Pollution and Control
  • Environmental Health and Safety

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