IOWA DOT PROVIDES UPDATE ON WORK NEAR MISSOURI RIVER CROSSING AT DECATUR, NE
(AMES) The Iowa Department of Transportation is reporting that flood mitigation work on Iowa 175 in Monona County, Iowa near the Missouri River crossing at Decatur, Neb. will be finished today. The contractor will be demobilizing equipment from the site.
Severe riverbank and bridge berm erosion caused by the flooding has occurred along the east abutment of the toll bridge owned by the Burt County [Nebraska] Bridge Commission. The bridge carries Iowa 175 and Nebraska 51 over the Missouri River. Scour around the abutment, changes in the river channel caused by the high-velocity flood waters and instability of nearby soils resulted in the closure of the bridge June 27.
An Iowa DOT contractor has constructed a U-shaped rock berm that begins north and ends south of the crossing. The purpose of the berm is to help prevent further erosion from occurring, which could result in loss of the roadway approach to the bridge and threaten the abutment. The rock berm is designed to stabilize the embankment and reduce the churning motion of the flood waters next to the abutment, which contributes to the loss of soil.
An inspection of the abutment and embankment area will be performed by the Iowa DOT as soon as it can be done adequately and safely. Reopening of the bridge/road is dependent on a positive bill of health, meaning it is safe for travel. No timetable has been set to perform the work since the water level is too high and current too swift.
The U.S. Army Corps of Engineers has announced that it will begin reducing outflows at Gavins Point from 160,000 cubic feet/second (cfs) to 155,000 cfs July 30; and 155,000 cfs to 150,000 Aug. 1; then holding the 150,000 cfs through Aug. 12. It is estimated that a further reduction in the water levels will be needed to perform the required inspection.
The public will be kept informed of any changes regarding status of the road/bridge.