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<br />March 1, 2004 <br /> <br />South Platte River Basin <br />District 1 <br />Diversion Structure Inventory <br /> <br />1 Empire Dam <br /> <br />Narrative of Structure Components and Repair Plan <br /> <br />The Empire Dam structure consists of a dam/spillway that is approximately 340 feet <br />long. There are a total of 29 concrete piers and 28 timber stoplog gates. By adding and <br />removing the 2x6 timber sections, the water surface elevation of the dam can be <br />manually controlled. The nose of each concrete pier and upstream edge of the concrete <br />maintenance/access deck are protected with embedded structural steel angles and <br />plates. The diversion structure contains five 10-foot-wide steel radial gates, making its <br />total width approximately 58 feet. <br /> <br />Although the overall condition of the dam/spillway portion of the structure is good, some <br />repair work is recommended. For the north 1/3 of the dam/spillway, significant sediment <br />deposition was observed, and upstream dredging is needed. The downstream portion of <br />the north endwall has broken off, and significant cracks are present. As a temporary <br />measure to help prevent further erosion, the wall has been extended downstream and <br />keyed into the north bank with sheetpile. The existing wall should be sawcut <br />immediately upstream of the damaged area, and extended approximately 30 feet <br />downstream. For partial wall replacement, refer to the "Crack Repair" paragraph of <br />Section 4.0, Conceptual Repair Plan. Toward the downstream end, the new portion of <br />wall should be angled outward to key into the north bank. Additional bank stabilization <br />should be placed along the north bank to help prevent future anticipated erosion. There <br />is a significant crack through the north dam/spillway pier, which should be replaced. <br />Minor cracks and spalling in the concrete deck and remaining piers were also found, and <br />should be repaired. The original handrail along the dam/spillway is no longer present. <br />To help prevent collection of debris during higher flows, a collapsible handrail should be <br />installed along either side of the deck. <br /> <br />The diversion is in very good condition. The headgates are partially rusted, but appear <br />to be well maintained. There is no trash rack present upstream of the structure. <br /> <br />Summary of Recommended Repairs <br /> <br />Dam/Spillway <br />o Dredging upstream <br />o Remove and replace/extend portion of north endwall <br />o Remove and replace northernmost concrete pier <br />o Install stabilization along north riverbank <br />o Repair damaged concrete (cracks, spalling) <br />o Install collapsible handrail <br /> <br />Diversion <br />o Monitor condition of headgates <br />o Install trash rack <br /> <br />Estimated Ranae of Cost <br /> <br />Low: $0 - $250,000 <br /> <br />Farnsworth Group <br />