Update on closure of Missouri River bridge near Decatur, Neb. (Monona County, IA)
September 6th, 2011 by Ric Hanson
AMES, Iowa – Sept. 6, 2011 – The Iowa Department of Transportation (DOT) is continuing to closely monitor the Missouri River flooding situation at the Iowa 175 bridge crossing near Decatur, Nebr., and is working behind the scenes so that it is prepared to begin repair work just as soon as conditions permit.
Preliminary inspection work has revealed a deepening of the river channel around the bridge pier by as much as 42 feet, and serious scour and loss of embankment near the bridge abutment on the Iowa side has occurred.
Emergency work to prevent further loss of the embankment and roadway itself was completed earlier. Since then, the stability of the embankment has deteriorated further, preventing additional work from being performed adjacent to the bridge at this time.
The Missouri River level has been dropping as the releases from the Gavins Point Dam have decreased, but the land adjacent to the roadway remains inundated with flood waters, leaving the road extending out into the widened river channel like a long boat pier. See the latest images of this area.
The next step that must be taken to restore travel on the bridge is to fill the void that exists around the pier so that it is stable and safe enough to support traffic. This will require placement of a large volume of material in the river bottom. Attempting to place material in the river at this point would not be successful because the flood waters are too deep and fast, and would cause the material to simply wash down the river. This work will begin as soon as conditions allow.
Meanwhile, the Iowa DOT is working with the Burt County Bridge Commission and Nebraska Department of Roads to finalize reconstruction plans. A meeting is also being scheduled with several contractors that are experienced with dredging and hydraulic pumping work to evaluate various concepts for making the repairs. Site conditions make this a very unusual and challenging project; and working with the private sector will help determine the feasibility of the reconstruction concepts.
The Iowa DOT recognizes the inconvenience for travelers due to this closure and is doing everything possible to expedite the recovery work by having all emergency contracts in place to begin work when conditions permit. A team of individuals is dedicated to evaluating all options, including nontraditional approaches and innovative ideas, to get traffic moving again in western Iowa as quickly as possible.
For regular updates on the Iowa DOT’s flood recovery progress, visit: http://www.iowadot.gov/floods/index.html