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<br />~ 2-(") (~... <br />t. <br /> <br />WEST RANGE WASH DIVERSION DIKE <br /> <br />SEDIMENT TRANSPORT ANALYSIS AND DIKE SIZING CRITERIA <br /> <br />IIIITRODUCTlON <br /> <br />The West Range Wash Diversion Dike (Figure 1) is intended to intercept and divert flows from <br />th'3 headwaters of the western tributary of Range Wash and direct them to the North Las Vegas <br />DE!tention Basin. To accomplish this, a dike alignmeil1t which tmverses the West Flange Wash <br />alluvial fan was established in a previous project unde:rtaken by 130yle for the City of North Las <br />Vegas (1991 Facility Planning Study). The offorts presented in the present study were <br />IJndertaken to determine an appropriate dike height which satisfies the design mquirements <br />stipulated by FEMA. These requirements include consideration of depth of flow, scour or <br />deposition potential, hydrostatic and hydrodynamic: head, flooding depth and appropriate <br />fre(~board for the 100-year peak flow. <br /> <br />The methodologies and results presented in this report follow the general procedures proposed <br />in the Memorandum of Understanding (MOU) dated Septembm 27, 1991 (Exhibit A). Changes <br />in the selected methodologies have been made only where required to develop information <br />which was previously assumed to be available from other sources. Boyle Engineering <br />Corporation and Dr. Richard French have worked closely on the formulation and execution of <br />the approaches presented herein. A compmhensive Design Notebook containing the <br />calculations, graphs and computer output has been produced and is availabi'3 for review. <br />Various sections ofthe Design Notebook are refen3ncecl herein. <br /> <br />A simplified flow chart of the evaluation process is attached as Figum 2 to facilitate presentation <br />and understanding. The major steps utilized are summarized below: <br /> <br />o Review Hydrology <br /> <br />o Determine Average Annual Sediment Yiel,j <br /> <br />o Compute Event Specific Yield <br />Inflow Sediment Load <br /> <br />Fan Equilibrium Flow Using Dawdy /FEMfl, <br /> <br />Integrate to Verify Average Annual Yield <br /> <br />o Model Fan/Dike System <br /> <br />HEC-6/Yang <br /> <br />Alluvial Fan Transport <br /> <br />Dike Equilibrium Transport <br />