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4.2.2 Impact Basin and Energy Dissipation <br /> The impact basins at the termination of the interconnect pipelines in Overland Ponds 2 and 3 <br /> and Treiber A will be hanging baffle type reinforced concrete structures based on U.S. <br /> Bureau of Reclamation (USBR) design procedures, as detailed in EM 25 —Hydraulic Design <br /> of Stilling Basins and Energy Dissipators (USBR, 1984). The impact basin properties are <br /> shown in Table 4. Impact basin calculations are included in Appendix D. <br /> Table 4: Interconnect Properties <br /> Pond 1 to Pond 2 to Pond 2 to Treiber A to <br /> Pond 2 Pond 3 Treiber A Treiber B <br /> Interconnect Interconnect Interconnect Interconnect <br /> Parameter Impact Basin Impact Basin Impact Basin Impact Basin <br /> Impact Basin Location Pond 2 Pond 3 Treiber A Treiber B <br /> Impact Basin-Interior Width 8 <br /> (feet) 0 8.0 9.0 9.0 <br /> Impact Basin Interior Height 6.0 6.0 6.75 6.75 <br /> (feet) <br /> Optimal Flow Range (cfs) 42-74 42-74 55-95 55-95 <br /> Maximum Discharge at <br /> Normal Pool with Zero 69 74 144 168 <br /> Tailwater(cfs) <br /> Maximum Velocity at Normal <br /> Pool with Tailwater at 32 35 0 73 <br /> Normal Pool (feet/second) <br /> Minimum Riprap D50 (inches) 9.0 9.0 9.0 9.0 <br /> The impact basins at the downstream end of the Pond 2/Treiber A and Treiber A/Treiber B <br /> interconnects were sized for a range of flowrates less than the maximum discharge. It is the <br /> intention of the owner to avoid fully opening the gate under conditions that would produce <br /> peak flow rates (i.e. upstream reservoir at normal water surface with empty downstream <br /> reservoir). The normal operational discharges are expected to be much less than the <br /> maximum discharge. As such, the impact basin was sized for optimum performance for <br /> flows within the normal flow range. <br /> Riprap will be placed around the impact basin and downstream of the basin outlet in the <br /> event that maximum discharge is released through the interconnect. Type M Rprap will be <br /> placed on the downstream embankment face and around the impact basin to protect against <br /> overspray and scour. Riprap will also be placed for a minimum of 8 feet downstream of the <br /> impact basin outlet. <br /> G E( Hydrology and Hydraulics 1 12 <br />