As hurricane protection goes, so goes New Orleans' future

U.S. Army Corps of Engineers has more than 140 projects in the works to try to reduce the risks to New Orleans from the next hurricane.

This newly constructed levee protects an affluent neighborhood of New Orleans from Lake Pontchartrain, which is just across the street. The levee is made out of a thick clay and will be seeded with grass in order to help prevent erosion of the wall by water that might overtop the levee in the case of a major storm surge. Daniel Terdiman/CNET News.com

NEW ORLEANS--When I wrote Wednesday that large parts of this city are still severely damaged from Hurricane Katrina and, in some cases, potentially beyond recovery, I didn't want to leave the impression that nothing is being done to protect against the next big hurricane.

In fact, the U.S. Army Corps of Engineers is putting large sums of money and significant effort into helping to reduce the risk that a future storm of Katrina's magnitude will inundate New Orleans.

All told, the Corps of Engineers here are working to fix and/or replace 220 miles of levees and floodwalls; build new flood gates and pump stations at the mouths of three outfall canals; and strengthen existing walls and levees at important points. More than $1.2 billion worth of contracts have been awarded for such work.

Of course, the Corps wants New Orleans' residents to know that nothing it can do will guarantee their protection. In fact, Corps public information officer Randall Cephus told me that the agency's efforts have been rebranded as risk management rather than hurricane protection because of a sense that the latter gave people a false impression that they would surely be safe in a Katrina-level event.

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As part of Road Trip 2008, I spent several hours this week with Cephus, driving around New Orleans as he showed me a series of the Corps' major projects.

And while there is certainly a significant amount of distrust of the Corps' past, present, and future efforts, it cannot be said that the organization is doing nothing.

One of the first things Cephus showed me was a crew working on a levee adjacent to Lake Pontchartrain. The efforts focus on keeping floodwaters from eroding the levee from behind, should the water top it. That type of erosion happened during Katrina, and it's obviously a serious danger to the city.

As a result, the Corps has developed two systems for dealing with this problem. First is using a thick clay to build the levees and then planting grass on them as a way to build roots that can bind the clay and help prevent the erosion.

Another way is to top the levee with cement splash guards, or armor as Cephus called it. This, too, is designed to keep the walls from eroding from behind.

As I reported Wednesday, the city's Lower Ninth Ward is still--and is likely to remain for a very long time--a disaster area. Many residents there fear that a future hurricane will result in additional flooding that will wipe away any gains made there.

But one plan the Corps has for avoiding this is to build what it calls a surge reduction barrier out beyond the mouth of the Bayou Bienvenue, which was part of what flooded the district during Katrina. The barrier would be designed to hold back storm surge that is heading toward the Lower Ninth Ward--as well as New Orleans East and the St. Bernard Parish, which were both also severely damaged by Katrina--from the east. This, however, is only a concept, and no work has been done on it yet.

A second source of flooding during Katrina was a breach in the city's 17th Street Canal.

This new gate system is designed to protect New Orleans from storm surge that would push up through the 17th Street Canal, which breached during Hurricane Katrina. Daniel Terdiman/CNET News.com

As a result, the Corps built--and began operation of in 2006--what is known as an outfall canal closure structure. This is essentially a gate that is 27 feet tall, 12 feet wide and 15 inches thick and features 280 tons of reinforced steel and can be shut down in the case of a hurricane and which, it is hoped, will prevent a major storm surge from inundating the canal.

The system also includes a series of major pumps designed to push water that does get through--either from topping the gate or from torrential rains--back out of the canal and into Lake Pontchartrain. The hope is that by doing so, the floodwalls along the canal will never be breached again.

Cephus said it's important to recognize is that no single piece of the risk prevention system can itself protect the whole city from a future hurricane. Rather, he pointed out, it is a complex system made up of innumerable parts, each of which shoulders the burden for a piece of the puzzle.

Many New Orleans residents think that the Corps has dragged its feet and that it can't be trusted to do what is necessary to protect the city. But Cephus maintains that the agency is working hard to help prepare for the next giant storm.

Of course, if such a storm were to happen in the next couple of years, there could be serious problems. That's because the entire body of risk prevention work that the Corps is doing here isn't expected to be completed until 2011. And some question even that date.

But some projects are already finished, and others are close. As can be expected with such a complex system--with more than 140 total projects involved--individual pieces will come on line, one after another, over the interim period.

The pump system behind the new 17th Street Canal gate is designed to push water out of the canal in case of a hurricane. The idea is to keep the canal from flooding and potentially breaching, as it did during Hurricane Katrina. Daniel Terdiman/CNET News.com

One project that has already been completed is the renovation of many of the floodwalls along the various canals that lead into the city. Previously, they were built with what is known as an I-Wall construction. This involved a series of piles coming down from underneath the wall that just drove straight down below the surface, with no additional support on either side. This style of wall was proven to be inadequate for the amount of water that came from Katrina's storm surge.

Now, the Corps has updated the walls with what is called a T-Wall construction. This system involves piles driven as far as 67 feet below the surface, as well as a series of diagonal steel support beams on either side that go down as far as 110 feet.

Whether these new style walls will stand up to the next great hurricane is, of course, unknown. But the Corps and the thousands of New Orleans residents are hopeful that everyone involved has learned from the past and that the pain experienced by so many during and after Hurricane Katrina will never be repeated.

 

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