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Subsidence, weak links in the levee system and poor funding also played a role in disaster, study says. (Photo courtesy |
The system “did not perform as a system,” says Ed Link, director of the Corps-sponsored Interagency Performance Evaluation Task Force. In addition to directing IPET, Link is a senior fellow and senior research engineer at the University of Maryland. He released the task force findings in New Orleans on June 1, the beginning of hurricane season and the deadline set by the Corps to restore flood protection to per-Katrina standards.
Lt. Gen. Carl A. Strock, the Corps’ commander and its chief of engineers, acknowledged the agency was at fault for enormous loss of life and property due to the failures of the storm protections last year. “This is the first time the Corps has had to stand up and take responsibility for a catastrophic failure,” Strock said. He said he accepted that the Corps is accountable for “our design and follow-up,” but also said it would be a waste of precious time to get bogged down in “lamenting the failures” when so much work remains. “We are not wringing our hands,” Strock said. “We are rolling up our sleeves and going to work.”
The report cites several combined failure factors: the unfinished condition of the city’s storm protection system, undermined by decades of subsidence and weak segments within it. The disjointed management structure of the 350 mile-long network of levees and flood control structures contributed, Link says, but the disaster’s root cause lies in outdated government methods for establishing need and from that, inadequate funding of systems construction.
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Related Links: “We, as a nation, have a water resources model that I think is no longer good for the future,” says Link. “The way we determine need, assess risk and go about funding and approving these things is based on a model that might have been appropriate for the way we lived 50 years ago, but is sorely outdated today.”
More resilient levees are needed for protection, Link says, but they will cost more. “Resilient systems are very difficult to justify in an economically-based system of justification,” he says. Stronger flood control systems require robust design and construction, but also need to be fully integrated with uniform monitoring and maintenance as well as systems for continuous risk and reliability assessments—aspects not typically accommodated in current economic-justification schemes.
As he has pointed out before, Strock noted that public policy and funding play an integral role in what the Corps may do. Unlike the private sector, the Corps must be “specifically authorized to take action and receive appropriations,” Strock said. “When we ask Congress for appropriations for a project, it is a snapshot in time. As things change, we do not have a responsive process to address those changes.”
Strock says this lack of a process to address changing conditions has hampered the Corps’ ability to respond to dynamic environmental conditions and advancing technology. He says the political process involved in advancing projects contributes to the problem and the solution calls for philosophical changes in operations. He says he is developing a 12-point proposal for water project management. “We do need a mechanism that recognizes dynamics, and we must do a better job of linking research to application,” Strock says.
Silver Lining
In the meantime, Strock says New Orleans’ defenses are assuredly better prepared for this hurricane season than they were before Katrina, primarily because the Corps has been incorporating into the ongoing levee repairs the IPET expert recommendations as they have been developed over the last several months. It is an approach that Link says has paid off well.
“It would have been of very little use to put forth the information on June 1 and say what did and didn’t work, if the Corps had not built what we learned into their work,” Link says.
For example, after finding serious design flaws with I-walls in several locations, and acting under the assumption that all I-wall construction is therefore suspect, the Corps has taken 20 of the 56 miles of I-wall construction “out of the equation” by providing storm-gate closures to three major outfall canals, and is taking specific measures to strengthen I-walls in other areas, Strock says. “We are bolstering some with stability berms, relief wells, and pilings,” he says. “Our assumption is that all I-walls are suspect but we are still doing assessments, and we have confidence in some in the system.”
The Corps has asked Congress for funding to replace all of the I-walls. However, even if the funding is approved, construction could not be completed during this hurricane season.
IPET findings will also be applied as design guidance for future protection projects. Examples of IPET-inspired changes include the use of deeper sheet piles; hardening or armoring the levees behind floodwalls to protect against scour and erosion if floodwalls are overtopped and strengthening the transition zones where earthen levees tie into concrete structures. IPET findings have already been used in the decision to provide interim closure structures at New Orleans’ three outfall canals; the re-development of stability calculations on I-walls throughout the system and to re-establish wave and surge analysis standards.
The IPET report, commissioned by Defense Secretary Donald Rumsfeld last fall, represents the work of about 150 leading engineers and scientists from federal, state and local government agencies, academia and private industry. Its nine volumes detail everything from the local geographic characteristics associated with specific reaches of levees, to performance of the system’s various components, to the consequences of the failure and risk and reliability.
“It’s hard to get your arms around the product,” says Link, referring to the final draft. “Since the devil is in the details, I hate to tell you this, but you really need to read the whole thing.”
The key concerns of New Orleans area residents this hurricane season are whether they will be safe, and whether the Corps can protect the city. In response, Strock notes that, “No matter how strong your systems, there is always some residual risk. There is no guarantee for any system.”
Strock adds that although it is technically possible to protect New Orleans, the questions that must be asked are whether it is economically justified, and whether it is environmentally acceptable to do so. Those determinations are up to Congress, he says, and adds, “The question is also, ‘What are you protecting against?’ Our job is to articulate an educated level of risk. Promising to keep the system to a certain level—no matter what—is like writing a blank check.”
The American Society of Civil Engineers has conducted peer review of the IPET work throughout the process. Its representatives were also present at the presentation. “The ASCE took that seriously in terms of being as honest, critical and constructive as we could,” says Christine Andersen, director of Dept. of Public Works for the City of Long Beach, Calif., and a member of the ASCE’s External Review Panel.
“This has been a pretty phenomenal effort to pull this together, especially considering that so much of the data was perishable,” Andersen says. “We didn’t constrain ourselves to the limitation IPET had. ERP took a broader view that incorporated things like organizational issues and breakdowns. There is a critical need, especially in New Orleans with multiple jurisdictions and authorities, for a National Levee Inventory and Assessment System.”
Responding to that need for a larger view of the organizational issues, Strock says the Corps is now developing a database to incorporate all federal projects, as well as a more robust levee inspection program that will include development of a risk-based analysis technique. “I think it makes tremendous sense,” Andersen said. “Levees have not had same amount of attention that dams have had.”
ast year’s catastrophic flooding of Greater New Orleans is the result of an outmoded national water resources management system and the U.S. Army Corps of Engineers’ inability to synch research findings, field application and changing technology, concludes a task force of scientists and engineers who presented a 6,615-page draft final report on their findings June 1.
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