We have been told of all the improvements to the Great Wall of New Orleans but remember walls can still be breached.
By tradition, the start of hurricane season marks a moment when New Orleanians begin warily eyeing the city’s drainage pumps, the turbines that power them and the massive series of floodwalls and levees that ring the region. For a change, there is reason to breathe a bit easier this season. The pumping and power situation may not be the ideal officials are working toward, but it has stabilized enough that the frightening vocabulary used to describe it in recent years no longer applies. The levee system, which recently marked its completion, stood up to what amounted to a moderate challenge from the storm surge of Hurricane Ida. Combined, those factors mean that within the walls and levees that ring parts of Orleans, Jefferson and St. Bernard parishes, the threat is less acute than it has been since the region’s defenses failed during Hurricane Katrina. But outside that protection, where some of Ida’s most significant damage occurred, it will still be years before new structures are put in place.nola.com
With hurricanes we face two threats.
Each hurricane carries the potential of two watery threats to the New Orleans area. There’s storm surge, the mass of water pushed from the Gulf of Mexico onto land that can overwhelm communities without protection, as happened to coastal areas during Ida. Much of New Orleans, Jefferson and St. Bernard are protected by a levee system that received $14.5 billion in upgrades from the U.S. Army Corps of Engineers after Katrina exposed huge failures in the design and maintenance of those defenses. In some ways, Ida served as a test of that new system, though an imperfect one. The surge on the west bank did rise high enough to provide a measure of confidence that the levees would hold up to their designs, which are intended to protect against a storm with a 1% chance of occurring each year. But east of the Mississippi River, the surge was hardly a challenge for the massive structures. Even Corps officials said they worried that people would take the wrong message from Ida. Though the agency is proud of how the system performed, spokesperson Ricky Boyett said he was afraid some people might have overestimated Ida’s surge threat, giving people a false sense of security and perhaps leading them not to evacuate or heed other warnings should a more serious danger arise. “There’s a complacency that comes with people thinking that the system stopped this massive event. And my biggest concern is that while people’s risk level is lower than it ever has been, it’s still there,” Boyett said. “When the system does well, our fear is people will become too comfortable.” The highest surge recorded near the levees was on the west bank, where high water marks of between 6 and 12 feet were found in areas outside the system. The defenses in that area are between 9 feet and 16 feet high. The National Hurricane Center has estimated that, had Ida’s track been 15 miles to the east, it could have overtopped the levees.
This suggests that the installed systems do work.
The Ida experience suggests the system’s design and construction was capable of meeting its goals, said Rick Luettich, a professor at the University of North Carolina who helped developed a storm surge model used by the Corps and previously served on the east bank levee authority. The defenses in place during Katrina, by contrast, failed in surges smaller than those they were built to withstand. “That was well within the conditions that caused systems to fail during Katrina; that starts to get to a situation in that location that I would say it’s a validation,” he said. On the east bank, the National Hurricane Center estimated the storm surge reached a maximum of 8 feet. The levees that ring the region are a minimum of 14 feet high, with some higher than 30 feet. That means those levees have seen less of a challenge, though Luettich said the performance on the west bank gives reason for optimism. “It’s easy to be skeptical, because you look at the old system and say that wasn’t so good. But I think the new system has the benefit of a lot of that learning,” he said. “For me, Ida was small in a geospatial sense but certainly a validation that they got the design right and gives me optimism that other parts of the system can hold up to storms that meet the design.” If overtopped, the levee system is designed to hold up without breaching against a 500-year storm. That means that — if all goes as planned — such a surge would cause localized flooding but not lead to the devastating breaches the region saw during Katrina.
The second threat is also water, but from the sky.
The second threat of a major storm is rain. New Orleanians know well the dangers that can pose after years in which severe summer thunderstorms were enough to flood streets, cars and in some cases houses. But officials at the Sewerage & Water Board, which is charged with drainage in New Orleans, say that while its system is still aged, it’s facing down hurricane season with more redundancy than in past years. The S&WB has two challenges when a storm approaches: Making sure the pumps that are needed to evacuate water from the city are working, and making sure they have the power they need. All but four of the 99 major drainage pumps in the city are currently in operation, roughly on par with where things normally stand, S&WB Executive Director Ghassan Korban said. Ida is estimated to have dropped about 9 inches of rain on New Orleans, an amount that has caused significant flooding in the past. But the inundation in the city was far more localized than in the most dramatic floods in recent years, limited in large part to areas of the west bank and Lakeview, where some problems owed to Entergy outages.
No matter what happens, the S&WB is the one we love to hate.
The bigger news for the S&WB may be its power situation. For years the S&WB has struggled to generate enough power for pumps that run on an old standard — known as 25-cycle power. Those account for roughly half the system’s pumping capacity, with Entergy powering the others. During each of the past two storm seasons, the S&WB went into major hurricanes with barely enough working turbines to run pumps at their maximum level, meaning a failure would force pumps offline. This year, roughly 88 megawatts of 25-cycle power are available through a combination of three turbines, four generators and power converted from Entergy. That means that if there are failures, other equipment can take its place. “It’s still an old system and it’s prone to failures,” Korban said. “So we have to be cautious, you know, not be overly optimistic about things. But we have redundancy and that creates comfort; if one thing breaks we have other options to use.” A more expansive effort to convert the entire system to Entergy power, with the existing turbines and a new one used as a backup, will not be online until 2024.
To take care of the surge and rain, there are long term fixes that are being done in the area.
Longer-term, work is ongoing on other major storm defenses in the area. But those levees will be unable to provide much, if any, protection this year. The West Shore Lake Pontchartrain project, aimed at giving the river parishes the same level of protection as New Orleans and its suburbs, broke ground last year, but work is still in its earliest stages. The 17.5 miles of levees were originally proposed in the aftermath of Hurricane Betsy in 1965. But the $760 million project only started to gain traction after Hurricane Isaac caused massive damage in LaPlace in 2012. Funding only came through in 2018. Work on the levees aren’t expected to be completed until 2024. To the southeast, the New Orleans to Venice levee project is working to bolster defenses from the upgraded system — which ends in St. Bernard Parish — down to the end of Plaquemines Parish. Levees there are currently built to withstand a storm that has a 4% chance of occurring each year; after the project is over, they will be able to handle a storm with a 2% chance of striking. Congress has provided $780 million for that project, which is years from completion.
The problem is that no matter what we do we are still sinking and the water is still rising.
Of course, for all the improvements, southeastern Louisiana continues to face existential threats. The region’s sinking land and the rising sea levels caused by climate change mean there needs to be constant efforts to maintain defenses. “Climate change, subsidence, all of those things — just simply aging — maintaining the levee system at its design height and what its design height needs to be — makes all of that challenging,” Luettich said. “Everyone I know believes those levees need constant attention and will as long as New Orleans is there.”
It means we keep up the defenses and hope that our sinking and water rising it now going to hurt them until more fixes are thought up.