Would New Orleans levees hold for a second Katrina?
Five years after Katrina, New Orleans is rebuilding. The system designed to protect against future storms is better than before, but questions remain about whether it is fortified enough.
New Orleans — Normally, moving to a new house in a new neighborhood is a transition many can feel good about. But for Randy Pratt, an electrician, moving his family into a brick home in this city’s Lower Ninth Ward makes him shrug at the possibility of lightning striking twice.
He now lives a short walk from where a concrete barrier collapsed on Aug. 29, 2005, allowing rushing water to destroy the neighborhood that only recently started to rebuild. Does moving back to what many consider the scene of the crime make him hesitate?
“I’ve been around levees my entire life,” says Mr. Pratt. “I just hope it’s safe, that’s all.”
His faith in the city’s 350-mile levee system, and therefore in the US Army Corps of Engineers, the federal agency in charge of maintaining it, is something that everyone living in this city shares in different proportions.
There is good reason.
What was first reported as the worst natural disaster in US history was later redefined as a breakdown in communication and maintenance by the Army Corps. Volumes of material written in the wake of hurricane Katrina, including a report released by the agency in 2006, determined that the flooding that drowned 80 percent of this city was due to faulty levee design, eroding materials, inconsistent levels of resiliency in different sections, pumping stations that were not designed to work during large storms, and other hazards that undermined the protection most had assumed was there.
“We got damaged by an engineering failure that caused the levees to break. We couldn’t control that. The federal government owns and operates the levees,” says Mayor Mitch Landrieu, interviewed in his city hall office earlier this month.
Expecting a hurricane, not a flood
Mr. Landrieu says despite the warnings, many city residents did not evacuate because waiting out hurricanes was common and there were few expectations of what came next. “We were expecting a hurricane but we got a flood,” he says.
Five years later, the city is rebuilding, its troubled public school district is undergoing dramatic reforms, and entrepreneurship is energizing neighborhoods and attracting new residents. The system designed to protect the city is certainly better than what existed before the storm, but questions remain about whether it is fortified enough.
Col. Robert Sinkler, commander of the Hurricane Protection Office for the Corps, says the ring of the levees before Katrina operated as “a system in name only.” Its weakness, he says, was the result of floodwall sections that were not consistent in their construction strength or maintenance. Missteps, like the use of dredging materials instead of construction-quality soil or clay, to build barriers in some areas, or the integration of sections that forsook structural resiliency for height, led to a “patchwork” of protection.
The $15 billion allocated by Congress to streamline the system is being used to mend areas that toppled, upgrade pumping facilities, build new floodgates, and reconstruct walls where there was obvious structural weakness.
This time, tougher foundation material, such as a mixture of construction clay and cement, is being used in the soil to hold structural sections of wall designed as an inverted T instead of their previous I-shape. The new design is considered stronger, allowing steel pillars to bracket each end into the ground. Completion is expected in June 2011.
The Corps says the reinforcements are built to provide a defense against a 100-year storm surge, which means protection against flooding that in any given year, may have a 1 percent chance of taking place. For a peak storm surge, such as one that may occur once every 500 years, the system is designed to allow overtopping, where a storm sends waves over the top of the wall. If that happens, a strengthened pumping system would remove the water in a matter of days and would not be considered as catastrophic as what happened during Katrina.
100-year defense ‘misleading’
John Barry, author of “Rising Tide,” a definitive history of the 1927 Mississippi River flood and a member of Southeast Louisiana Flood Control Authority East, which oversees six levee districts, calls the 100-year designation “misleading” because it implies the area is safe for that length of time.
But as years go by, the odds of a storm surge impacting the levee system increase. This will become especially true, he says, as coastal erosion brings the Gulf of Mexico closer to New Orleans, impacting sea levels and the strength of future storms.
“It’s the lowest standard in the civilized world. It’s government on the cheap,” he says.
Mr. Barry says the levees should be constructed to withstand a 1,000-year flood, adding that Holland enjoys a 10,000-year protection standard.
Raising minimum flood standards is costly. In 2007, Sacramento, Calif., area property owners agreed to finance $326 million of a $2.7 billion project to raise the flood protection standard of Folsom Dam to a 200-year level by 2015.
Risks never eliminated
However, Sinkler says the very nature of where New Orleans sits in relation to both the ocean and the Mississippi River means that whatever line of defense the Corps builds will never “eliminate all risk.” He says the current national standard for 100-year protection is “a political decision on how much risk the national and the local government is willing to accept.”
Mayor Landrieu says he plans to argue for increased protection, including pressing President Obama to make it a priority of ongoing recovery efforts.
“Until we get that we can’t comfortably say – to the extent that you ever comfortably say that you’re protected from Mother Nature – that we’re as well protected as we can for the risks that we know may be coming our way,” he says.
For some residents, the insecurity raised since Katrina persists. Diedra Taylor, who lives in a new home across the road from the levee breech that destroyed her old home, plus the majority of the Lower Ninth Ward, says she isn’t afraid that a second storm will undo the progress made over the last five years.
However, if a storm as powerful as Katrina is reported on the horizon, she is certain of one thing: “We’ll just leave. We won’t wait around to see if the Corps of Engineers did their job.”