Some of the most celebrated levee repairs by the Army Corps of Engineers after Hurricane Katrina are already showing signs of serious flaws, a leading critic of the corps says.
The critic, Robert G. Bea, a professor of engineering at the University of California, Berkeley, said he encountered several areas of concern on a tour in March.
The most troubling, Dr. Bea said, was erosion on a levee by the Mississippi River Gulf Outlet, a navigation canal that helped channel water into New Orleans during the storm.
Breaches in that 13-mile levee devastated communities in St. Bernard Parish, just east of New Orleans, and the rapid reconstruction of the barrier was hailed as one of the corps’ most significant rebuilding achievements in the months after the storm.
But Dr. Bea, an author of a blistering 2006 report on the levee failures paid for by the National Science Foundation, said erosion furrows, or rills, suggest that “the risks are still high.” Heavy storms, he said, may cause “tear-on-the-dotted-line levees.”
Dr. Bea examined the hurricane protection system at the request of National Geographic magazine, which is publishing photographs of the levee and an article on his concerns about the levee and other spots on its Web site at ngm.com/levees.
Corps officials argue that Dr. Bea is overstating the risk and say that they will reinspect elements of the levee system he has identified and fix problems they find. The disagreement underscores the difficulty of evaluating risk in hurricane protection here, where even dirt is a contentious issue. And discussing safety in a region still struggling with a 2005 disaster requires delicacy.
Hurricane season begins again next month.
The most revealing of the photographs, taken from a helicopter, looks out from the levee across the navigation canal and a skinny strip of land to the expanses of Lake Borgne. From the grassy crown of the levee, small, wormy patterns of rills carved by rain make their way down the landward side, widening at the base into broad fissures that extend beyond the border of the grass.
Dr. Bea, who was recently appointed to an expert committee for plaintiffs’ lawyers in federal suits against the government and private contractors over Hurricane Katrina losses, said that he could not be certain the situation was dangerous without further inspection and that he wanted to avoid what he called “cry wolf syndrome.” But, he added, he does not want to ignore “potentially important early warning signs.”
He praised the corps for much of the work it had done since the storm, but he added that the levee should be armored with rock or concrete against overtopping, a move the corps has rejected in the short term.
Another expert who has viewed the photographs, J. David Rogers, called the images “troubling.” Dr. Rogers, who holds the Karl F. Hasselmann chair in geological engineering at the University of Missouri-Rolla, said it would take more work, including an analysis of the levee soils, to determine whether there was a possibility of catastrophic failure.
But he said his first thought upon viewing the images was, “That won’t survive another Katrina.” Dr. Rogers worked on the 2006 report on levee failures with Dr. Bea.
John M. Barry, a member of the Southeast Louisiana Flood Protection Authority-East who has also seen the photographs, also expressed worry. “If Bea and Rogers are concerned, then I’m concerned,” he said.
Mr. Barry, the author of “Rising Tide: The Great Mississippi Flood of 1927 and How It Changed America,” said it was important to seek balance when discussing the levees in the passionately charged environment of New Orleans since the storm.
“I don’t want anybody to have any false confidence” in the system, he said. “On the other hand, if things are improving, people need to know that, too. And things have been improving.”
After being informed of the safety questions, Senator Mary L. Landrieu, Democrat of Louisiana, prepared a letter to send today to the corps commander, Lt. Gen. Carl A. Strock, asking whether the work by the corps was sufficient to protect the levee system.
At the corps, Richard J. Varuso, the assistant chief of the geotechnical branch of the district’s engineering division, said that some erosion could be expected after a levee was constructed. “If it rains, we get some rutting,” Mr. Varuso said, adding that as vegetation grows in, the levee “heals itself.”
Walter O. Baumy Jr., the chief of the engineering division for the New Orleans district of the corps, said the new levees were made with dense, clay-rich soil that would resist erosion. Although the stretches of the St. Bernard levee that were still standing after the storm are composed of more porous soils dredged from the nearby canal, Mr. Baumy said a reinforcing clay layer on top some 10 feet thick would keep the fissures from reaching the weaker soils.
Still, he said that “we will take a look at this” and that the corps would make repairs where necessary.
Dr. Bea, who wrangled with the corps last year about construction standards on the same levee, countered that recent work in the Netherlands suggested that clay-capped levees with a porous core, which are common, were prone to failure in high water.
Another official who viewed the photographs, Robert A. Turner Jr., the executive director of the Lake Borgne basin levee district, east of New Orleans, said he was concerned, but not necessarily alarmed, about the rills toward the crown of the St. Bernard levee, calling them a common sight on new levees in the area.
Mr. Turner said he was more concerned by the images of larger ruts toward the base of the levee, and said of the corps, “We’re just going to keep on them.”
Mr. Turner said the corps had been responsive to issues raised by local officials. “They’re out there trying to prove to everybody under the sun that they built everything correctly,” he said.
“That is a big departure from the way the corps used to operate pre-Katrina,” he said, but added: “They got so much negative publicity before, they can’t afford to do it wrong. They’ve got to do it right.”