FLOOD10207 - Laserfiche WebLink

Home Browse Search

SECTION IV FLOOD HYDROWGY Section IV discusses the use of previous flood studies, precipitation data and two models for the detennination of Rocky Flats flood hydrology characteristics. The two models discussed herein are the Colorado Urban Hydrograph Procedure (CUHP) and the Stonnwater Management Model (SWMM). Factors that detennined the choice of models, the models themselves, and model results are explained in this section. Flood hydrographs, peak flows and volumes are presented for a range of stonn events. The determination of the drainage and flood hydrology characteristics of the Rocky Flats Plant site included full consideration of the basin descriptions as presented in Section III of the "Rocky Flats Plant Drainage and Flood Control Master Plan" (Master Plan), along with previous studies performed by U.S. government agencies and private consultants for the Department of Energy (DOE). The drainage and flood hydrology analyses presented herein was designed to closely follow the analytical procedures laid out by the Urban Drainage and Flood Control District Manual (Wright McLaughlin, 1969). The Urban Drainage and Flood Control District (UDFCD) includes the Rocky Flats drainage basins. UDFCD has served as reviewer on this Master Plan, along with the State of Colorado, and generally support the methods and findings presented herein to the limits expressed in their correspondence (see Appendix II-A in the Master Plan introduction). Selection of precipitation durations for the Rocky Flats Plant hydrologic study included 2- hour design storms for a variety of frequencies of occurrence to satisfy local technical criteria. The 2-hour design storm is consistent with the UDFCD Manual procedures and applicable to the Rocky Flats area. Flood determinations were also made using 6-hour design storms which are identified under DOE Order 6430.1A, Section 0270 (DOE, 1989)