Upper Arkansas River Divsion 2 Diversion Structure Inventory.pd

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Upper Arkansas River Division 2 Diversion Structure Inventory concrete, significant cracking or rust, and the structure appeared to be between ten and fifty years old" Structures in fair condition require considerable annual maintenance to operate properly. Structures that looked as if they were over fifty years old with obvious structural failure or serious damage were considered poor. Poor structures may have been repaired many times to remain functional, but are in need of further repair. In some cases, it may be more cost effective to completely replace a structure in poor condition. 4.0 CONCEPTUAL REPAIR PLAN The basic features, visible damage, and a conceptual repair plan are described in a short narrative for each structure, which can be found in Appendix B. Crack Repair - There were different types of cracks encountered, with most structures having at least some minor cracking. Hairline cracks are commonly found in concrete, usually do not affect the integrity of the structures, and do not generally require repair work. Cracks that are approximately }'8-inch to % -inch in width are significant, and will usually require repair. Injecting a pressurized grout into hairline cracks is generally a good method to repair hairline cracks in a concrete structure. Bridging across cracks with a series of straps fastened to the concrete surface is another option to slow any movement between two adjoining sections of concrete that would normally require complete or partial replacement rather than repair. If a portion of a concrete structure requires replacement, steel reinforcement should be doweled into the existing portion of concrete, and the dowels should be connected to the steel reinforcement placed within the new section. Stabilization - River bottom, channel bottom, and bank stabilization is typically recommended in locations where the hard surface (usually concrete) of a structure ends and soil begins. However, the need for stabilization will ultimately depend on the type of soil, the flow velocity through the structure, and the erosiveness of the soil. The potential damage to downstream soil caused by flow through the structure will also depend on the setting or orientation of the gates. Since the gates are frequently adjusted, the velocity of flow is frequently changing and the resulting damage is unpredictable. It is recommended that the material used for stabilization be riprap or grouted boulders. The designer will determine the layer thickness of riprap or sizes of boulders, which will be based on anticipated flow conditions and take into account factors such as velocity, geometry, danger of undermining the basic structure, etc. It may not be feasible to use riprap or boulders in some cases, and access to a quarry may be limited. In such cases concrete rubble could be used, as long as it is of the same approximate design size and layer thickness as the riprap or boulders. Following the narrative is a Summary of Recommended Repairs and an Estimated Range of Cost for each structure. Rather than providing a conceptual Olsson Associates Page 3 June 2005