As hurricane protection goes, so goes New Orleans' future

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.

(Credit: 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.

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.

(Credit: 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.

(Credit: 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.

[Renegade Knight]

The question that I have is what is the lifespan of the improvements? Meaning when will NOLA have sank enough to where the Army Corps of Engineers has to do it all again. Risk managment is probably a good term. The risk is nerver zero, and it will go up every single year as the city keeps sinking. Rather like LA waiting for the "Big One".

[Penguinisto]

To be honest, there comes a point of diminishing returns. It would likely be cheaper (and in the long term safer) to simply move large sections of New Orleans somewhere else.

[doctorj2u]

The joke of the work done by the Corps of Engineers is that all the new work will give New Orleans what they promised us we already had before Katrina. So when the president promises flood protection better than ever, what he really means is to make it what it was supposed to be to begin with. The forensic studies done on the levees after the storm showed the design of the levee system did not come close to giving the protection that was promised. Go to levees.org and see what the citizens of New Orleans are fighting for.

[CSnDC]

First let's put things in perspective. Sea levels area expected to rise by an average of 7 to 21 inches in the next 85 years (NOAA data). The average rate of sinking in New Orleans is 1/5 inch p/y but in 10-20 percent of the area (such as lower 9th adn St. Benard) the rate is 1 inch per year. by 2095 this put the worst effected areas at a possible additional 9 feet below sea level. A significat amount for calm waters forget a level 5 Katriana Hurricane. The reasons for the sinking in N.O. are seismic shift, diverted ground water, alteration of the Mississippi R. (MR) and over-development. Seismic shift cannot be dealth with, however, returning significant portions of the lowets lying areas to nartural habitat along with a revised system of levees and canals the entire length of the MR and it's feeder rivers, the Ohio, Missouri, etc. would rebuild the Delta and slow or stop major portions of N.O. from being lost for good. In the MR pushing all levees back 1/2 to 1/4 mile in un-nhabitated areas including farmland would preven flooding disasters all along the MR and its feeders. A one lane canal wide enough for a full barge or fairy (with intermittent pass lanes) down the middle of the MR and its feeders along with the changed levve system would allow sediment to flow naturally down the MR (as it had for a millinea) and re-deposit on the MR Delta. In the mean time the Army COE could assist the process by building significant earthen works on the outer delta and the Dept of Forestry could replant and see the new ground - this could also be done by private contractors. This would add significant new jobs to the local and US economy and prevent future economic loss not only in NO but throughout the South and Mid-West.

[William Crow]

New Orleans is sinking...what a waste of fuel...not carbon efficient. Abandon the project.

[CrabkillaTX]

THIS IS A WASTE OF TAXPAYER MONEY!!!!!!!

Since when does it become logical to build below sea level?

If you build below sea level, expect floods.
If you build near an active volcano, expect fire
If you build in the Bahamas, expect a hurricane
If you build near a fault line, expect an earthquake
If you build near a airport, expect noise.
If you build near a large river, expect floods.

It is not the govenments job to bail out stupidity.

[paulej]

CrabkillaTX, it is a bit more complicated. When folks settled New Orleans, this was not expected. The city grew and grew and now, here we are. I agree that it would be stupid to go build a city below sea level, but the fact is that the city is already there. So, we have two options: re-build and try to manage the potential threat or move the whole city up river. Over a 100-year period, what will cost more? Having said that, I do think it might be wise for folks to consider re-locating new structures elsewhere. The city should make a long-term plan to re-locate and turn vacated properties into wildlife reserves over time.

[paulej]

CrabkillaTX, it is a bit more complicated. When folks settled New Orleans, this was not expected. The city grew and grew and now, here we are. I agree that it would be stupid to go build a city below sea level, but the fact is that the city is already there. So, we have two options: re-build and try to manage the potential threat or move the whole city up river. Over a 100-year period, what will cost more? Having said that, I do think it might be wise for folks to consider re-locating new structures elsewhere. The city should make a long-term plan to re-locate and turn vacated properties into wildlife reserves over time.

[JRip MN]

NOLA should move inland an up to higher ground. The entire protection system was ONLY designed for a Category 3 storm and we know these storms come in Cat 4 and Cat 5. Simple math says NOLA is doomed.
AND
IF we could stop messing with the river and let the fishing grounds recover we might some day get more of the seafood that NOLA and the Gulf coast are famous for.
AND
see prior comments from others for rising sea levels etc.

[jimoase]

Considering the costs to recover New Orleans and the reoccurring costs to keep the levees up .... maybe it would be cheaper to buy everyone off and put up National Park signs. We can use a nice Gulf Cost National Park.

When some talks of the character of the area.... are they saying the land or those people who have already left town?

Jim