Standing atop the parapet of the new 26-foot-high surge barrier overlooking Lake Borgne, it's easy to understand the record-shattering accomplishments of the Army Corps of Engineers that will provide "100-year" protection to New Orleans area parishes on the southern side of Lake Pontchartrain in time for the 2011 hurricane season.
The $1.1 billion structure is designed to block the crashing arrival of hurricane surge water and waves from the Gulf of Mexico through Lake Borgne that would otherwise stab two miles west through the Gulf Intracoastal Waterway and Industrial Canal into the heart of New Orleans.
The barrier runs from a new 32-foot-high combination T-wall and earthen levee in St. Bernard Parish, cuts across the now-abandoned Mississippi River-Gulf Outlet navigation channel, and then runs across the Golden Triangle wetlands patch to another combination T-wall and levee in eastern New Orleans. "We've been able to pull (the levee system) from people's back yards," corps New Orleans District commander Col. Ed Fleming said.As amazing as that accomplishment is, it doesn't mean residents living behind the new system are not at risk from hurricanes, emergency preparedness officials warn.
"If we have a Category 3 or higher storm with a high probability of the area getting hit, we are going to order a mandatory evacuation because of the risk involved with a storm of that magnitude," said Lt. Col. Jerry Sneed, New Orleans deputy mayor for public safety.
The threat is from both wind damage and some overtopping of the new system, officials say.
St. Tammany Parish residents have received some assistance from the corps with drainage improvements after Hurricane Katrina, but the development of ring levee systems to protect Slidell, Mandeville and Covington may have to wait until Congress approves larger Category 5 hurricane protection for the state's entire coastline.
Meanwhile, the corps still is working on raising levees in Plaquemines Parish that are part of the federal New Orleans-to-Venice system, and some small segments that are "non-federal," and will be lower than the new 100-year standards.
Deadly lessons learned
The new system represents an unprecedented engineering feat that took six years to build, with more than $8 billion spent so far on design and construction. And it required a complete rewriting of the rules used by the corps to build both levees and hurricane levees.
The new system began, of course, with the deadly lessons learned in August 2005 during and immediately after Hurricane Katrina: The previous batch of individual levee projects was dubbed "a system in name only" by then-corps Chief Engineer Lt. Gen. Carl Strock that was never upgraded to account for soft and sinking soils, outdated construction materials, or the likely chance that dramatically larger hurricanes could hit the area than those for which the system was designed.
"This has been sobering for us, because it's the first time the corps has had to stand up and say we had a catastrophic failure with one of our projects, " Strock said on June 1, 2006, in addressing the first draft of a report on why the previous system failed.
Ed Link, research engineering professor at the University of Maryland who chaired the interagency task force that wrote the study now includes a simplistic question on his final exams for honors classes:
"What does it take to make progress with regard to reducing risk?" he asks. "The answer is a disaster."
In Katrina's aftermath, it was the storm's catastrophic effects that resulted in Congress agreeing to spend $12.8 billion in federal money, to be matched by $1.5 billion in state and local money, on improving the levee and interior drainage systems in the New Orleans area.
The new system accomplishes three goals, said Col. Robert Sinkler, commander of the corps' Hurricane Protection Office, created to oversee levee construction on the East Bank in the aftermath of Katrina.
The first, best represented by the 1.8-mile barrier wall along the northwest edge of Lake Borgne, was to block surge from entering canals that reached into the heart of the region's residential and commercial communities, he said.That also includes construction of a barrier gate at the Seabrook entrance to the Industrial Canal from Lake Pontchartrain; the three temporary gates on East Bank drainage canals in western New Orleans, and surge-blocking improvements to pump stations in Jefferson Parish; and the West Closure Complex on the West Bank that will block surge from the Gulf of Mexico entering the Harvey and Algiers canals, and smaller gates and closures on other West Bank canals. The West Closure Complex includes 11 vertical pumps able to move water out of the Harvey and Algiers canals at a rate of 19,140 cubic feet per second, making it the largest drainage pump station in the world. It also includes a 225-foot-wide navigation gate, and a complicated T-wall design along the edge of the federally protected Bayou aux Carpes wetlands.
A second goal was to apply new levee and floodwall standards to existing parts of the system, Sinkler said, to improve the "resiliency" of individual pieces of the system, their ability to still be standing in the aftermath of overtopping, even from a larger, 500-year storm.
"We went through and ensured that everything was engineered, designed and constructed to the same standards, no matter what parish it was in, no matter where it was in the system," he said. "In many cases, we ended up ripping out tens of miles of either levee or floodwall and replacing it, even if it wasn't overtopped during Katrina."
Finally, the corps has "stormproofed" about 50 pump stations within the levee system, assuring that if portions of the city are flooded, operators can safely continue to run pump stations to remove water, he said.
Underlying the design and construction techniques is an equally dramatic change in the way the corps and the nation's engineering profession deals with risk. No longer is the combination of levees, gates and floodwalls considered a hurricane protection system; it's a risk-reduction system, designed to protect property and not people.
State and local officials also contend the new 100-year system is limited in its protective abilities this year because of temporary measures used by the corps to meet that goal by June 1.
Incomplete projects include a 15-mile stretch of Mississippi River levees along the West Bank between English Turn and Belle Chasse that was being raised after new modeling last year showed hurricane surge combined with a high river might push river water into Algiers. Construction was halted three weeks ago by this year's river flooding and won't resume until the river drops below 15 feet, not expected until August.
The Seabrook gate that would block surge from entering the Industrial Canal from Lake Pontchartrain won't be complete for at least a year, but a steel sheet-piling caisson filled with dirt is high enough to block 100-year surges.
Temporary gates and pumps at the ends of the 17th Street, Orleans Avenue and London Avenue drainage canals will remain in place for as long as three years. A contract to build permanent pump stations and closure structures at the three canals has been challenged by a competing bidder.
Corps officials expect to fill several other small gaps in walls and levees still under construction with sheet piling or Hesco baskets and sand bags in advance of tropical storms.
Biggest storms still pose grave threat
But state and local officials also warn that even when complete, the system won't protect from larger, potentially catastrophic hurricanes.
In addition to wind speeds of 111 mph or greater for Category 3 and greater hurricanes, the surge accompanying such storms could cause overtopping of the new system, according to risk modeling conducted by the corps in 2007. In the lowest areas of the region, such overtopping could result in 5-foot flood levels from the combination of surge and rainfall.
New modeling of the completed system to better estimate potential flooding during larger hurricanes won't be available for several more months, officials say.
The so-called 100-year design standard is surge created by a hurricane with a 1 percent chance of occurring in any year, such as 120-mph, Category 3 Hurricane Rita in 2005; 105-mph, Category 2 Gustav in 2008 and possibly even the 110-mph, Category 2 Ike, also in 2008. By contrast, Katrina was a 400-year event in terms of its surge hitting the Mississippi coast and about a 250-year event at Lake Borgne, according to corps scientists.
"By the same token, 100-year protection is an extraordinarily low standard, and I feel odd in terms of celebrating," he said. "I think what it indicates, really, is the need for us to do a lot more.
"The chances of going 100 years without a storm that exceeds the level of protection we've been afforded is not much better than 1 in 3, so the odds are almost 2 to 1 against us," he said.
And while the corps is stressing the resilience of gates and walls, Barry remains concerned about the earthen levee portions of the system, and the possibility that the corps may rely on grass as "armor" to protect the interior parts of levees from erosion during overtopping.
Equally concerned about armoring and temporary measures is Garret Graves, chairman of the state's Coastal Protection & Restoration Authority, which oversees regional levee authorities and local levee districts in the New Orleans area, and acts as the official local sponsor for the levee system.
"What we will have is duct tape," Graves said, half-joking.
"I think it's important to note that many components of this system are stronger than ever before, higher than ever before, and that's very positive," he said. Graves has repeatedly questioned the corps' assurances that it will have enough money to pay to armor the protected side of earthen levees to assure that overtopping during larger storms won't cause them to erode away or fail, as occurred in Katrina.
The corps contends that a significant chunk of the approximately $6 billion remaining from congressional appropriations is available for that purpose. But two weeks before the beginning of this hurricane season, the agency still had not determined whether using grass, a combination of grass and geotextile fabric, rock or concrete will be required.
'We can't just build a big wall'
But Graves' concern also is about the ability of the new structures to provide enough protection from the largest storms without the restoration of surge-buffering wetlands and land ridges to the south and east of the city.
"An important lesson from Katrina is we can't just build a big wall around and isolate ourselves and expect that to be sufficient," he said. "The painful lesson we learned from Katrina is the Gulf of Mexico encroaching upon the New Orleans area is not okay."
Even as Congress approved money for the 100-year levee system, it also ordered the corps to develop a plan to protect New Orleans and other Louisiana coastal communities from even higher surges created by the "equivalent of a Category 5 hurricane."
The Louisiana Coastal Protection and Restoration Study was supposed to be completed by 2007. Sent to Congress last year, it included an initial estimate of between $70 billion and $136 billion for building a combination of higher levees and expansive coastal restoration projects. The report also concluded that the corps needed more input from the state before choosing which projects to build.
"All the report did was create more haze, rather than a clear blueprint for the future," Graves said. But he quickly added that the corps and other federal agencies now have assigned key staffers to the state's own effort to create a blueprint for the state's coastal levees and restoration.
That effort is the first rewriting of the state's 2007 master plan for coastal restoration and protection, due in 2012, which state officials say will include just such a list of restoration and protection projects. Annual updates of the original master plan already are used as financial blueprints for the state Legislature to distribute state money between restoration and levee projects.
Graves said that despite the dim chances of getting Congress to throw more money into the state's levee and restoration pot, the state may be able to direct between $10 billion and $20 billion toward coastal restoration projects, largely using money from federal and state civil and criminal litigation against BP for its Deepwater Horizon oil spill.
Whether the money flow occurs, the reality is that New Orleans will reap dramatic benefits from the engineering and science devoted to the new system.
The key to that process was to redefine the risk facing the city in modern terms, Link said. That began with the abandonment of the past corps practice of adopting key features of historic hurricanes to create a single test storm that would be thrown against the city in modeling to determine levee heights and strength requirements.
Led by Donald Resio, senior research scientist with the corps' Coastal and Hydraulics Laboratory in Vicksburg, Miss., officials developed a new system to define the hurricane hazard faced by the city.
"The hazard was developed by ... looking at what we knew about hurricanes and the physics of ... a broad spectrum of storms that consisted of different sizes, intensities and paths that would represent a range of events that were fairly common, in a sense of something like a 50-year event, to something uncommon, like something like a 3,000- to 5,000-year event," Link said. Included was the potential for more intense storms, the result of global warming.
Applying the best 156 of those storms against the outlines of the New Orleans area, the researchers determined how high segments of the levee system should be, incorporating the effects of sinking soils and the potential rise of sea level, again caused by expected global warming.
At the same time, other engineers were rewriting the rules used to build pieces of the system, based on the knowledge gained from Katrina failures, Link said. Instead of just looking at the most likely failure methods, the new rules required pieces to be strong enough to withstand all but the most remote failure potentials.
New construction methods
As the corps moved toward designing and building pieces of the new systems, officials also adopted new construction techniques and new contracting methods.
For instance, the Lake Borgne barrier project went to a consortium of companies under a "design-build" contract, the largest ever awarded by the corps, for the largest barrier of its kind in the world. It also represented the largest continuous placement of concrete, with more than 1,000 truckloads, since construction of the Hoover Dam.
The project used three of the five largest cranes in the nation for pile driving; those cranes were among the 18 floating cranes used at the height of construction.
On the West Bank, the $1 billion West Closure Complex is now the largest drainage pump station in the world, containing more than 18 million pounds of metal rebar, equivalent to the metal used to build 30,747 airplanes.
Corps engineers also used new construction methods to deal with the area's soft soils. In eastern New Orleans, where levee heights range from 19 to 27 feet, contractors mixed cement with soil deep beneath the ground to provide a more stable platform. In another eastern New Orleans segment, the corps built the largest wick drain project in the nation, which allows water squeezed from soft soils by the weight of levees to be collected and drained away safely.
In addition to the armoring and permanent East Bank pump stations, the corps still must choose and build several environmental restoration projects to mitigate the adverse effects of construction, at a cost estimated between $200 million and $250 million, Sinkler said. Construction of interior drainage improvements, which represents another $1.5 billion, will continue through 2017.
Mark Schleifstein can be reached at firstname.lastname@example.org or 504.826.3327.