WASHINGTON (May 7, 2007)–Despite nearly two years and more than a billion dollars spent by the U.S. Army Corps of Engineers to repair the New Orleans levee system since Hurricane Katrina, experts say the repaired system will almost certainly fail if hit this year by a Katrina-sized hurricane — or even a smaller storm.
Robert Bea, an engineering professor at the University of California, Berkeley, flew over the levee system with a team from National Geographic magazine and found it riddled with flaws, including a rebuilt floodwall that is seeping water, a brand-new levee that is already eroding, and holes in the floodwalls that still have not been closed. The U.S. Army Corps of Engineers declared almost a year ago that it had restored the barriers to pre-Katrina strength.
The most serious flaws turned up in the rebuilt levees along the Mississippi River Gulf Outlet ship channel, which broke in more than 20 places when Katrina’s storm surge pounded it, leading to devastating flooding in the Lower Ninth Ward and St. Bernard Parish. Bea found several areas where rainstorms have already eroded the newly rebuilt levees, particularly where they consist of a core of sandy and muddy soils topped with a cap of Mississippi clay. “It’s like icing on the top of angel food cake,” Bea said. “These levees will not be here if you put a Katrina surge against them.”
Bea also found that decade-old gaps remain in the floodwalls lining the Orleans Avenue Canal, and hurricane-damaged sections of the walls along the London Avenue and 17th Street canals have not been repaired or replaced. Even more troubling, water appears to be seeping under the stout new floodwall erected along the Industrial Canal to protect the Lower Ninth Ward. The new wall sits atop steel sheet piles driven 20 feet into the ground, but water from holes in the canal bed, excavated before Katrina or scoured by the storm, may be seeping under the barrier through permeable layers of sand and silt. Bea said the wall could fail in the next hurricane.
The floodgates also have no mechanism to remove sediment and other debris that might keep them from closing as a storm approaches. The Corps says it will rely on divers to check for obstructions and clear them away.
Ivor van Heerden, deputy director of Louisiana State University’s Hurricane Center and leader of a team of state experts that examined the levee failures, concurred with Bea’s list of weak spots and says they are representative of others throughout the system. He added that a section of I-shaped floodwall along the Duncan Canal in Jefferson Parish — the city’s western defense — is another weak link. “There is 1,900 feet of I-wall that actually dips — sinking from its own weight,” he said. Sheet pilings installed by the Corps to shore up the weak wall may not be adequate, he warned.
The Corps said the city’s flood defenses are a work in progress. “After Katrina we achieved a massive accomplishment, repairing the damage that occurred,” said John Meador, deputy director of Task Force Hope, the Army Corps group rebuilding the hurricane protection system. “We believe we are putting the system back better than it was before Katrina, but we’re not at an end point yet. Any time we’re made aware of such situations, we address them immediately.”
National Geographic magazine’s Web site, www.ngm.com, has a full report on flaws in the New Orleans levee system. The August 2007 edition of the magazine will include an article on the challenges facing New Orleans.
National Geographic magazine is the official journal of the National Geographic Society, one of the world’s largest nonprofit educational and scientific organizations. Published in English and 29 local-language editions, the magazine has a global circulation of around 8.5 million. It is sent each month to National Geographic members and is available on newsstands for $4.95 a copy. Single copies can be ordered by calling (800) NGS-LINE, also the number to call to apply for membership of the Society.