WASHINGTON (Army News Service, Aug. 17, 2015) -- Throughout the last 10 years, U.S. Army Corps of Engineers personnel have dedicated their lives to rebuilding the storm and hurricane protection system in New Orleans, Col. Richard Hansen said.

"They've taken it very seriously. They saw what happened during [Hurricane] Katrina. They heard criticisms about the Corps of Engineers. They took that very personally and they made a promise to themselves and to the agency that it wasn't going to happen again," said Hansen, who has been the New Orleans District commander for nearly three years.

Hurricane Katrina hit southern Louisiana 10 years ago, Aug. 29, 2005. The storm was a Category 3 hurricane with sustained winds of 125 mph.

The 10th anniversary of Katrina is, "on the one hand, a very somber occasion," said Hansen, noting the deaths of 1,833 people, most of who were in Louisiana, according to the U.S. Census Bureau. Damage was estimated at $151 billion.

"On the other hand, it's remarkable how the city has rebuilt," he said.

For the first time since Katrina struck, New Orleans returned in 2014 to the list of the nation's 50 most populous cities, ranking 50th at 384,320. The city's population had been 494,294, July 1, 2005, before dropping to 230,172 one year later, according to a U.S. Census Bureau news release, dated July 29, 2015.

In many ways, that "rebirth was a result of the effort that has been put into building the storm protection system around the city," Hansen said.

PRE-KATRINA

The flood protection system in place before Katrina was "a system in name only," Hansen said. It had been built very incrementally, with limited funding over many years, and still was only partially finished at the time when Katrina hit.

The system didn't perform as well as anyone would have liked and there were parts of the system that were just overwhelmed, he said. Levees in the eastern part of the city had a 10-foot surge come over the top of the levee and that eroded it away.

Floodwall failures on several of the outflow canals, namely the 17th Street, London Avenue and the Inner Harbor Navigation Corridor, were later diagnosed as having deficiencies in the engineering, he said.

The Corps "had to work hard after Katrina to show that it was a learning organization. We sought to fully understand as much as we could what had happened during Hurricane Katrina so lessons learned could be incorporated into the design, the planning and construction of the system that's in place today," he said.

POST-KATRINA

The nation made a commitment after Katrina to protect the city and areas affected by the hurricane, he said.

"That was demonstrated by Congress providing $14.5 billion of full and up-front funding across two presidential administrations," which allowed the Corps of Engineers to build the hurricane and storm damage risk reduction system that exists today, as well as work with local, state, national and even international water-resource experts.

"We even coordinated with and worked with Dutch experts in the design and construction of this system and now we're going back with lessons-learned to them," he said.

The hurricane and storm damage risk reduction system that exists today is 133 miles of perimeter around the greater New Orleans area. It consists of earthen levees that are integrated with flood walls, pump stations and gated structures.

The Corps took a different approach to the pre-Katrina protection system. "We pushed the perimeter outward, straightened it out in many ways, and built closure structures across the outflow canals along Lake Pontchartrain. We build the Lake Borgne surge barrier that prevents the surge from entering into the interior of the city where it can threaten the 9th Ward, downtown, and other areas," he said.

Lake Borgne is a lagoon of the Gulf of Mexico, east of New Orleans. Lake Pontchartrain is north of the city.

"In some ways, the new perimeter takes on a military approach," he said, explaining that the perimeter has been pushed out and is now more heavily defended.

LESSONS LEARNED

Hurricane Sandy demonstrated that there isn't just a risk along the Gulf Coast. The lessons learned from Katrina that have been applied elsewhere are that "engineering standards need to be high," Hansen said. "We've developed more stringent material requirements. We've invested in a lot of cutting-edge science and technology [for] modeling and simulation, showing where the risks are in a 100-year storm event.

"This was not possible prior to Katrina," he said, explaining that a lot of the research was and is being done at the Corps' Engineer Research and Development Center, or ERDC, in Vicksburg, Mississippi, in collaboration with universities across the country.

In designing flood protection for New Orleans, ERDC modeled 152 storms, from 25-year to 5,000-year intensities, he said. ERDC then developed 63,000 hydrographs that show how a storm surge might behave at 350 points around the system at various locations in each of those 152 storms.

A 100-year surge means a 1 percent change of occurring on any given year, he said. "We made some very conservative assumptions. We assumed that in that 100-year storm you'd have peak wave period, peak wind and peak surge, all occurring at the same time. We assumed the worst-of-the-worst condition as we developed the design heights for the different areas around the system."

As of today, "we have not only a 100-year-level risk reduction, we have very robust 100-year-level risk reduction," he said, adding that the lesson to be learned from this is "invest and understand what the risk level is before establishing the standard and building, and then communicate that risk to the public."

Since Katrina, the Corps has been working together with other agencies, not as "stovepiped" agencies as was typically the case pre-Katrina, he said. "We're truly working as a synchronized and integrated team at the local, state and federal levels. That includes conducting exercises and training throughout the year, very much like you'd see in unit training throughout the Army."

PEOPLE MAKING IT HAPPEN

There have been thousands of Army civilians, Soldiers and contractors, "who've worked diligently over the last 10 years and they delivered a system that today provides 100-year-level risk reduction. It's the best level of storm risk reduction that this city has ever had in its history," Hansen said.

Those personnel include engineers, planners, environmental specialists, real-estate lawyers, construction inspectors and others.

The Corps has also had scores of officers and noncommissioned officers, active-duty and Army National Guard, who've been assigned here over the course of the last 10 years, he pointed out. These Soldiers that are assigned here as project engineers and other duties "bring with them a lot of energy, discipline, new ideas and I'd like to think they leave with a broader knowledge of how the Army can serve the nation through the Corps of Engineers."

About half of the Corps' workforce at the time of Katrina lived in New Orleans and they lost their homes and possessions just like the residents, he said. Although their houses were under water, they came to work, sleeping on cots the first few weeks.

"They were not able return to their houses to clean up and rebuild their lives for many months after. It was a very emotional event for them," he said.

During Katrina, Hansen was with the 1st Cavalry Division in Fort Hood, Texas, as a battalion executive officer. His unit patrolled the streets of New Orleans following Hurricane Katrina 10 years ago and now that he's the New Orleans District commander, he's trying to ensure such a disaster never happens again.

FUTURE RISK

Even as massive as this system is, there's still residual risk, Hansen warned. There's always the possibility of a larger storm. If there is a larger storm, there could be overtopping of the system.

"I'm often asked, 'where's the highest risk,' 'where is the system most vulnerable?' I say the risk is 'complacency.' This is a risk reduction system that's been constructed here, not a risk elimination system," he said. "No matter how high it is, there's always the possibility of that larger storm that could overtop the system. Residents and local governments will always have to be prepared to evacuate."