WSP01174 - Laserfiche WebLink

Home Browse Search

~ t 'i ~ i '. " i, 1 I I' , DEPARTMENT OF THE ARMY OMAHA DIsrRICT, CORPS OF ENGINEERS OMAHA, NEBRASKA 68102 SUPPLEMENT TO INTERIM REPORT AND APPENDICES, BEAR CREEK, COLORADO MOUNT CARBON RESERVOIR WITH OPrIMUM RECREATIONAL DEVELOPMENT PLAN September 1967 1. R!RPOSE Following review of the Chief of Engineers' proposed report on the Bear Creek basin, Colorado, the Bureau of Outdoor Recreation recommended certain substantial modifications in the recreational aspects of the dam and reservoir project recommended by the reporting officers and concurred in by the Board of Engineers for Rivers and Harbors. This supplement presents a discussion and evaluation of tbe reccmmendations made by tbe Bureau of Outdoor Recreation. It swmnarizes the project costs and benefits associated with such additional development, and it provides cost allocations and cost-sbaring data. 2. DESCRIPrION OF PLAN OF IMPROVEMENT a. Tbe reporting officers recommended a plan of improvement consisting of a multiple-purpose dam and reservoir on Bear Creek, approximately 8 miles upstream from the confluen~e of Bear Creek and the South Platte River, at Denver, tbat would provide flood protection for metropolitan ~nver and tbe rural reaches of tbe South Plexte River downstream from Denver. The Division Engineer recommended, as a potential maximum modification of the original plan of development, a plan essentially equivalent to the alterna- tive plan 5 presented in tbe basic report of tbe District Engineer. Re~ommendation of the more costly alternative was based on the probability that fOundation conditions unsuited to the original plan might be revealed during advanced planning studies, wben more detailed subsurface explorations would be undertaken. The recommended project, tberefore, represents tbe maximum structure that might be required under adverse foundation conditions. This would include an earthfill dam 162 feet bigh, witb. a crest length of about 4,400 feet, and a supplementary earthfill dike, with a beigbt of 50 feet and a crest length of 2,700 feet, to tbe south of the main embankment. An earth~ and rock-cut emergency spillway would be provided to insure the safety of tbe structure. The reservoir would provide storage capacity of 74,750 acre-feet, of which 2,400 acre-feet would be for sediment reserve and recreation, 26,000 acre-feet would be for flood control, and 46,350 acre-feet would be for surcbarge storage. An ungated service outlet would be provided for flood control releases, and a gated low-flow outlet would be provided for release of streamflow requirements. Pertinent data for the recommended project are presented in table 1. 7