The Walled City

17th street Canal
Aerial view of the levee failure at the 17th Street Canal following Hurricane Katrina

By Skylar Deckoff-Jones

In the original literature, Plato’s Atlantis tells of a utopian civilization living on an island perched in the middle of the Atlantic Ocean. Bent on world domination, the Atlanteans go to war with the Atheneans, lose, and ultimately have their homeland cast to the bottom of the ocean by the gods. The city of New Orleans is currently at war with nature to prevent a similar fate. However, instead of falling out of favor with divine beings, New Orleans is confronted with rising sea levels, sinking levees, and increasingly violent storms.

The 133-mile perimeter that circumscribes New Orleans is a carefully engineered daisy chain of earthen levees, concrete flood walls, and a multitude e of other complex structures. However, the current system is only a result of the catastrophic failure during Hurricane Katrina. The federally funded U.S. Army Corps of Engineers has reevaluated their flood management systems in an effort to keep New Orleans treading water.

“Katrina brought a lot of lessons,” said Ricky Boyett, the chief of public affairs for the U.S. Army Corps of Engineers. “From Hurricane Katrina, we learned that every storm is different. What we did is take 152 storms ranging from 25-year storms to 5,000-year storms. Around the entire levee system we took 350 points, and we ran the full 152 storm sweep for each point, getting over 50,000 different hydrographs which allowed us to establish what would happen at every specific point in the system.”

For perspective, Hurricane Katrina was considered a 300-year storm, meaning that there is a 0.3% chance for a storm of that strength to occur each year. The current system is designed to protect against 100-year level storms with the predicted sea level elevation of the year 2057. The corps has also redesigned the system to ensure a continuous perimeter about the city. “The industrial and intracoastal waterway canals go into the interior of the city. When they breached during Katrina, that was the water that flooded the 9th Ward and St. Bernard,” he said. Surge barriers were pushed further away from the heart of the city, and potential weak points such as the canals were targeted. “The system is only a strong as its weakest link. We can now make the greater New Orleans a walled city,“ Boyett said.

However, this brings little comfort to many New Orleans’ residents. Scott Van Newhouse, a resident of Gert Town New Orleans, has little faith in the Corps’ barricade. “If one minor problem in a wall is unreported, that problem could be an Achilles heel that brings down a whole section. When one section is breached, as we saw with Katrina the whole city goes under. That’s the problem with the wall: It only takes one section to flood all of lower New Orleans.”

Newhouse’s distrust of the Army Corps is not unwarranted based on previous allegations. Sandy Rosenthal, president of Levees.org, an organization dedicated to uncovering the truths of the New Orleans levee system, has helped to shed light on the corners cut by the Army Corps prior to Katrina. “Steel was costing a fortune to buy and drive into the ground. They did a study to see if they didn’t need to drive it down as deep. They determined instead of driving the steel down 50 feet, they could drive it down 17 feet instead.” This simulation error ultimately led to levees which were unable to withstand Katrina’s might. “They misinterpreted the results of the study. It wasn’t criminal, but if that had been a private company people would be in prison. But you can’t sue the federal government,” she said.

Perhaps what has most tarnished the Corps’ reputation was that this information was not made public until nearly 10 years after Katrina. “The engineering corps is known for its shadiness throughout the United States,” Newhouse said. “So I don’t think we can trust the government as it is now to tell the truth. They are in the habit of providing service, and they want to keep their contracts and jobs, so they don’t want to admit that these levees and systems are still inadequate. If it was a hurricane over category two, I would probably evacuate because this is a flood area that I reside in. I really don’t know if they can withstand the force.”

On the other hand, Boyett of the Army Corps is confident that they now can. “When we built a flood wall pre Katrina, we built what is called ‘I walls’. They look like an ‘I’, straight up and down into the ground. Post Katrina we built ‘T walls’. The T walls look like upside down ‘T’s. The pilings are driven into the ground straight down, but also out at an angle under the subsurface. It gives greater strength to withstand erosion and the pressure of a storm surge.” The engineering design has been objectively thorough, considering both structure and composition. “We also evaluated soil, and identified a particular type of clay that is good for constructing levees. It’s a resilient clay. We went down to the point where you can only have 0.001% vegetative matter in the clay. But we still know eventually they will be overtopped, so in addition to better clay, we’re going in and armoring them. What the armoring does is protect the levee when it is overtopped. With this armoring, when the water goes over, it doesn’t erode the levees. So when the water subsides, we can pump the water out, but the levee itself can still defend from further surges.”

Although these changes totaled 14.5 billion dollars of federal money, they have already been proven worthwhile. In 2012, the system was tested by Hurricane Isaac. Though there was flooding in the eastern areas of New Orleans, the storm system remained resilient under the intense pressu re of 13-foot surges. Boyett said, “After Hurricane Isaac there is a confidence factor in the levees; they performed exactly as they were designed to.” To this, Sandy Rosenthal notes that no two storms are created equal. “Hurricanes can be tight or they can be enormous, they can be slow or fast, and they can come in through the east or the west. A hurricane is one of the most difficult things to simulate. There are still problems on the lake to the west. If water comes into Lake Pontchartrain, it can keep coming around and flood New Orleans from the west. The levees need to be higher over there,” she said.

The Army Corps is ultimately under the command of Congress, and as Rosenthal explained, they are not always allowed to make the best choices. “To have had 1000-year protection, we needed to raise the levees another two or three feet, but President Bush said everywhere should have 100 year protection. The levees in Orleans Parish were built to the same pre Katrina height. Whereas St. Bernard Parish, where comparably no one lives, they had to raise their levees 30 feet. A fortune was spent to protect St. Bernard, but no one is there. That was a political decision, it wasn’t based on science or economics.” Nearly one tenth the population of Orleans Parish, St Bernard Parish has roughly one third of the levee system protecting it. It is a controversial concept to redirect resources towards more populated areas, but one which many New Orleans city residents support. “Those parishes are no longer even heavily populated. The coastal parishes are having land retreat and constant flooding as it is, so those people should be relocated with government assistance to other areas,” said Newhouse.

The most important change brought by Katrina is a shift in perspective of the function of the flood management system. “We called it the hurricane protection system, and today we call it the hurricane and storm damage risk reduction,” Boyett said. “We have removed the word protection because it gives a false sense of security. No matter how high we build this system, we know in the New Orleans area there will be a storm that is able to overtop this system. It will not breach like it did in Katrina, but there will be a storm that can overtop it.” Both Boyett and Rosenthal are in agreement that the public must revise how they view the flood management system. Rosenthal explained, “It’s an effort on the part of the federal government to let the residents know that you need to take on responsibility yourself. This takes on lots of forms – buying flood insurance, raising your house, evacuating, and having a plan.”

As the city reinforces its walls, Rosenthal is left with a fear for the long-term state of the city. “What worries me, keeps me awake at night, is that I see New Orleans being an island in the not too distant future,” she said. If one thing is clear, it is the resolve of both the people of New Orleans as well as the Army Corps to keep the city above water. The battle against nature continues to keep New Orleans from joining the ranks of Atlantis.

Skylar Deckoff-Jones is a Senior at Tulane studying Physics.

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