Lower Arkansas Districts 10_14_17&67 Diversion Inventory

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September 15, 2004 Lower Arkansas River Basin District 14 Diversion Structure Inventory 4 Bessemer Ditch Narrative of Structure Components and Repair Plan The Bessemer Ditch structure is located at the downstream toe of the Pueblo Reservoir Dam. The headgate(s) are not visible, since they are located on the upstream side of the dam. The opening at the downstream toe of the dam is approximately 10-feet-wide by 10-feet-high, with a semi-circular arch at the top. Downstream of the opening is an 80-foot-long chute, that transitions from 10-feet-wide to 12-feet-wide approximately 30 feet downstream. Although currently not visible, there appears to be a vertical lift gate approximately 50 feet downstream of the opening. At the downstream end of the chute, there is a 12-foot-wide by 5-foot-high opening with a headwall, wingwalls and a 20-foot- long concrete apron (does not appear to be used for energy dissipation). An open channel begins downstream of the apron, of which the first 25 feet is rock-lined. Rock protection is placed along the outside curves of the channel banks for stabilization. The concrete structures are completely surrounded with chain-link fencing. The overall condition of the structure appears to be good. The concrete walls are approximately 16-inches thick. There is a vertical cold joint in both walls along the chute approximately 25 feet upstream of the downstream headwall, where the walls have experienced 1 to 2 inches of horizontal differential movement. Along the inside curve of the channel downstream of the structure, the bank is near vertical, sloughing off and undercutting has occurred. The bank should be flattened to a minimum 3H : 1V slope for approximately 300 linear feet. Summary of Recommended Repairs Diversion/Chute o Stabilize cold joints in concrete o Flatten slope of bank downstream of structure Estimated Ranae of Cost Low: $0 - $250,000 Farnsworth Group