Olsson Associates

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Olsson provides services for new diversion structure at Ord

Thursday, July 11, 2013

Sarah Ferdico, Communications

Hardenbrook Diversion Structure at OrdIn June 2010, the North Loup River between Taylor and Ord, Nebraska, experienced severe flooding. The flooding was estimated to be greater than a 500-year flood event. The existing irrigation diversion structure owned by the North Loup River Public Power and Irrigation District located at Taylor was completely destroyed. The structure located at Ord, the Hardenbrook Diversion Structure, also suffered damage as a result of the flooding. The district selected Olsson Associates to design a replacement structure for the Taylor site and to complete a study of the structure at the Ord site.

In November 2010, Olsson completed the study of the existing structure at Ord and recommended that the Hardenbrook Diversion Structure be replaced due to structural damage. Olsson worked with the district to secure disaster recovery funding from FEMA/NEMA for the project. Olsson began working on the new structure design in October 2011. Olsson then bid the project in May 2012, and construction was completed in June 2013.

The new structure consists of four 20-foot-wide tainter gates for river control and one 16-foot-wide tainter gate for river control and sand sluicing, which keeps excessive sand from accumulating upstream of the diversion structure. A 530-foot concrete overflow spillway was constructed next to the diversion structure to provide relief during high river levels.

The system to divert the river into the district’s irrigation canal system is accomplished using eight seven-and-a-half-foot stop logs to control the surface debris, a sluicing chamber to control the sand volume in the diverted water, and seven eight-and-a-half-foot slide gates to divert the water into the irrigation canal. A control system was also part of the project to provide automatic level control for the river and irrigation canals.

The structure also includes a five-foot pedestrian walkway across the structure to allow fishing access to the northeast side of the river for local residents. Funding for the pedestrian walkway was provided by the Lower Loup Natural Resources District.

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