HAMBURG, Iowa (AP) -- Massive sandbags dropped on a faltering Missouri River levee have temporarily fortified the floodwall and given Army engineers more time to construct a secondary barrier to protect a threatened Iowa community, authorities said Monday.
The earthen levee, which guards an area of farmland and small towns between Omaha, Neb., and Kansas City, has been partially breached in at least two places south of Iowa's border with Missouri, and emergency management officials said they expect new breaches in the coming days as the river rises.
"We anticipate these compromises rearing their ugly heads all up and down the levee system throughout this event," Rhonda Wiley, the emergency management director for Atchison County, Mo., said Sunday. "It's not a pretty picture."
The Army Corps of Engineers began building a secondary flood wall to protect low-lying areas of Hamburg, Iowa, because it expects the northernmost breach of the floodwall, which is 5 miles southwest of town, to fully give way at some point.
That breach constituted a 10- to 15-foot-wide section of the levee collapsing in on itself on Sunday, Kim Thomas, the head of the corps' emergency management office in Omaha, said in a statement. The corps evacuated its personnel from the area and the Iowa National Guard used a helicopter to drop 22 half-ton sandbags on the weakened section, stabilizing it temporarily.
Although Hamburg is upriver, a full breach of that section of levee would cause floodwater to flow northward over the flat terrain and threaten the town's low-lying southern neighborhoods.
About half of Hamburg's roughly 1,100 residents were ordered Sunday to leave their homes within 24 hours, and that process should be completed by Monday evening, said John Benson, a spokesman for Iowa's department of Homeland Security and Emergency Management.
Several residents of Atchison County were also ordered to leave.
"People's safety is our number one concern, so we want to stress how important it is for the public to stay off of these levees as we continue to assess the risk," the corps' Omaha district commander, Col. Bob Ruch, said in a statement Sunday.
"We acknowledge the frustrations of the affected communities, and we are committed to working together to avoid the loss of life and minimize damages," Ruch said.
He said the corps has been working to raise the levee near Hamburg an additional five feet to help protect the town.
An earlier breach of the levee near Rock Port, 15 miles south of Hamburg, caused a leak that shot water like a "like a small geyser," said Gen. Derek Hill, head of the Iowa Department of Homeland Security and Emergency Management. Crews stabilized that partial breach, the corps said.
Officials are also concerned about a section of a levee on the river's western banks, near Brownville, Neb., and crews are trying to determine the extent of possible damage there, the corps said.
In South Dakota, the Army Corps of Engineers began construction of a backup levee Sunday to protect the town of Dakota Dunes. Corps engineer LeeJay Templeton said the 1.4-mile long secondary levee is slated to be completed by Thursday.
The Missouri River was expected to rise about 8 feet to 1,098 feet above sea level by June 14 in the city of about 2,500 people, some of whom have evacuated ahead of the planned crest. Officials said construction of the primary levee is still under way to protect the city 2 feet beyond the projected high level.
(Copyright 2011 by The Associated Press. All Rights Reserved.)