Design Refinement and Construction Drawings for Overshot Gates that Irrigation Districts can Construct Themselves
Project ID: 2319
Principal Investigator: Tom Gill
Research Topic: Supporting Irrigation Districts
Priority Area Assignments: 2011 (Climate Adaptation), 2012 (Climate Adaptation)
Funded Fiscal Years: 2011, 2012 and 2013
Can an overshot gate designing system be developed that would be applicable over a commonly encountered range of gate sizes while maintaining basic format suitable to enable users with a limited technical background to produce construction plans for gates that are cost effective to build and that exceed structural operational requirements?
Need and Benefit
Overshot gates are a popular means of upgrading control at a stoplog structure. Flow passing over an overshot gate behaves hydraulically similar to flow passing over stoplogs. Passage of floating debris is another similarity common to both overshot gates and stoplogs. For many existing stoplog structures, overshot gate systems may be designed that are simply lowered into existing stoplog slots.
Commercially produced overshot gates are available from multiple manufacturers. In many cases, they are not within a range of affordability that many districts can justify. A recently encountered example is the South Platte Ditch Company gate. Projected costs for all materials, labor to construct the gate, hot-dipped galvanizing treatment, plus all components needed for a solar-charged automation system equipped with radio communications equipment are approximately $6,000 for the 4-foot-wide gate. During a site visit this spring to a district in central Nebraska, project researchers were shown an overshot gate installation of similar dimensions -although constructed of stainless steel -that represented approximately a $30,000 investment for similar performance capabilities. This level of cost disparity makes a self-constructed overshot gate system attractive for many irrigation districts. A key factor in districts opting for self-constructed gates will be development of a simplified gate design system.
Bostwick Irrigation District, Nebraska
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