Corps: Floodwalls Built After Katrina May Sink Over Time
NEW ORLEANS (AP) — In response to concerns, the Army Corps of Engineers says it will monitor possible sinking over time of 23 miles of levee and floodwall protection it built after Hurricane Katrina to protect St. Bernard Parish, an area southeast of New Orleans that suffered catastrophic flooding in the 2005 storm.
In a report released Monday, the Army Corps says the weak soil beneath the levees and concrete floodwalls it built around St. Bernard could cause the 75-foot-long pilings to bend over time. But the agency stressed that there was no immediate concern and that there might not be any problems in the future.
The corps spent about $1 billion to build a much higher and stronger flood protection system around St. Bernard after Katrina.
Corps officials were not immediately available for comment Wednesday.
Katrina demolished the levees surrounding St. Bernard, which had subsided considerably by 2005. In the wake of the storm, the corps decided to rebuild flood protection by installing high floodwalls atop levees.
But the swampy soils where the new levees and 12-foot-high floodwalls have been built are weak, prompting outside engineers to warn as early as 2007 that sinking could affect the new structures over time. The floodwalls are held up by angled pilings and those pilings could bend as the land settles, the report said.
The corps report said one area of the floodwall could sink by as much as 21 inches over several decades. If the wall sinks, that could cause the pilings to bend and undermine the effectiveness of the flood protection.
In light of potential problems, the corps plans to install a $1 million monitoring system to keep track of stresses on the structures.
"We wanted them to re-evaluate the decisions they made and they have," said Stephen Estopinal, the president of the Southeast Louisiana Flood Protection Authority-East, an agency set up after Katrina to be responsible for running and maintaining the corps-built flood protection around New Orleans.
Estopinal praised the corps for doing the study and agreeing to install the monitoring system.
"We will have ample warning if there are concerns," he said. "It will be able to pick up changes well before there are problems."
– by AP Reporter Cain Burdeau