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I I I I I I I I I I I I I I I I I I I TUCKER GULCH / KENNEY S RUN FLOOD HAZARD AREA DELINEATION - PURPOSE AND SCOPE - - AUTHORIZATION - This report was prepared to guide local officials in planning the use and re~ulation of the lOa-year floodplain. The report includes information on past floods and the nature and extent of probable future floods along an approximate 9.4 mile study reach of Tucker Gulch, Kenneys Run and other studied tributaries. This report was authorized and contracted through the Urban Drainage and Flood Control District as part of a program of identifying floodprone areas within the District's jurisdiction. This study was prepared under the current format of the District's Flood Hazard Area Delineation Reports. The study scope consists of an analysis of the 10- and lOa-year flood events. Although not included in this report, water surface profiles for the 2-, 5- and 50-year floods were determined as part of the study contract for use in preparation of a Phase A, Major Drainage- way Planning Report for Tucker Gulch and Kenneys Run. This study identifies floodprone areas along Tucker Gulch, Cressmans Gulch, Kenneys Run, the East and West Forks of Kenneys Run, Deadman Gulch, and three other unnamed tributaries within the Kenney s Run drainage basin. The majority of the study area is within the City of Golden with the upstream study limits located in unincorporated Jefferson County. The floodplain information included in this report is provided by the Urban Drainage and Flood Control District to enable local governments to adopt and administer comprehensive floodplain management regulations. Included in this report are Flood Hazard Area Maps which show the areas that would be inundated by the lOa-year flood event. The water surface profiles show the 10- and lOa-year flood elevations along the channel related to Mean Sea level (MSl) Datum, .also referred to as National Geodetic Vertical Datum (NGVD). The report also includes information regarding the channel thalweg, existing drainage structures, stream bank elevations, typical floodplain cross-sections and flood flow characteristics. Upon acceptance of this report by the Urban Drainage and Flood Control District, and the designation and approval of the flood hazard areas by the Colorado Water Conservation Board, this study can be used by the City of Golden and Jefferson County to regulate future floodplain construction, to guide future drainageway improvements and to plan flood protection measures along the channel and flood- plain of the studied streams. A floodway was also computed as part of this study based on criteria specified by the District (maximum 0.5' rise on the energy grade line assuming equal conveyance reduction on both sides of the floodplain). Floodplain and flood- way data, including widths, elevations, velocities and reference data, is presented in Tabfe IV of this report. The floodway is provided to designate those areas to be kept free from future encroachment and reserve an area for conveyance of the lOa-year flood. Floodway criteria is designed to limit future increases in flood stage and velocity resulting from floodplain development.