NEW ORLEANS, LA (WVUE) - Flying in a helicopter over a giant surge barrier in eastern New Orleans, H.J. Bosworth marvels at what he calls, "a virtual civil engineering fortress."
Bosworth, an engineer who is the lead researcher for the group levees.org, has been a frequent critic of the U.S. Army Corps of Engineers in the days since Hurricane Katrina.
On an aerial tour of the system that now encircles metropolitan New Orleans, Bosworth generally heaps praise on the defenses designed to offer 100-year storm protection.
The 2-mile long Lake Borne Storm Surge Barrier rises 26 feet above sea level, a massive concrete and steel structure that locals have dubbed "The Great Wall."
"It is large enough to drive fairly large trucks across," Bosworth notes.
The barrier, one of the world's largest flood defense structures, is designed to knock down a Katrina-sized surge.
On August 29, 2005, two man-made navigation channels acted as superhighways for surge, funneling water into a "V" shape "like a cake pan tilting water in one corner."
Today, the Mississippi River Gulf Outlet is closed, blocked by the surge barrier and a giant rock structure 17 miles to the east. From the air, the MRGO closure is deceiving. While it stretches nearly 1,000 feet across the waterway, it peaks through the surface like an ice berg. Just 12 feet wide at the surface, it covers 450 feet at the water bottom. The Gulf Intracoastal Waterway in New Orleans East remains open, but a giant sector gate closes there at the surge barrier during storm events.
On the city side of the Great Wall, 140-foot steel piles slope at an angle into the earth to help anchor the wall in place.
Bosworth is similarly impressed with levee improvements. He describes the levee along the old MRGO prior to Katrina as "shabby" and "an accident waiting to happen."
Levees obliterated in Katrina have been completely rebuilt. From above, the viewer does not see the better materials inside levees, including sheet piles and concrete I-walls that form the skeleton of the levees.
"What we have now will largely protect us against a carbon copy of Katrina," Bosworth said.
He does voice concern that sheet piling under the old MRGO levee should have been coated to prevent salty, moist air from rusting it over time.
"We've got the protection," Bosworth said, "but where you've got a wall, it will turn part of it into a screen." The result over time, he says, will be "seepage and leakage, but certainly not catastrophic flooding."
The Corps insists it took corrosion into account when designing the levee projects.
In an email response to FOX 8, Corps spokesman Rene Poche said engineers used different methods to "inhibit or compensate for corrosion depending on factors that include the project design, soil conditions, location and construction materials."
In the case of the old MRGO levee in St. Bernard, Poche said the Corps used additional steel thickness over 23 miles of floodwall.
"The additional steel allows a certain amount of corrosion to occur while still having the needed size to perform as needed for the project's design life of 100 years," Poche said.
Based on inspections, the Corps maintains the piles show no indication of corrosion that would exceed the design parameters.
"In other words, we have no cause for concern over corrosion along the St. Bernard T-Walls," Poche said.
Closer to the heart of the city, another sector gates closes the Industrial Canal at Lake Pontchartrain. That provides a significant defense versus 10 years ago, when "nothing really prevented the lake from filling up the Industrial Canal."
The Corps is also working on three permanent pumping stations at the London, Orleans and 17th Street outfall canals. Earlier this week, engineers ushered reporters around the Orleans Canal construction site and declared construction to be roughly 50 percent complete. The Corps expects to hand the keys to the structures to local officials by the start of the 2017 hurricane season. In the meantime, temporary pumps provide a means of closing the city to the lake during storm events. The pumps operate only during a tropical event and not during a normal rain.
In all, the new Hurricane Risk Reduction System consists of 350 miles of levees, flood walls, gates and pumps designed to offer protection against a storm with a 1 percent chance of occurring during any given year.
The west bank, which dodged the most serious Katrina effects, had its own potential "MRGO" prior to 2005. The Gulf Intracoastal Waterway had threatened to funnel massive amounts of surge through a network of canals, inundating parts West Jefferson, Algiers and the Belle Chasse area.
Now, the world's largest drainage pumping station and North America's largest sector gate that together make up the West Closure Complex significantly lower the threat. The 225-foot sector gate closes off the GIWW while the pumping station drains 19,140 cubic feet of water per second from parts of three parishes. When operating at full blast, 5,000 horsepower engines and pumps could fill an Olympic-sized pool in less than 5 seconds.
"It gives us a great way to de-water the west bank in a way we never had before," Bosworth said.
Bosworth sees one potential trouble spot in extreme Eastern New Orleans at the foot of the I-10 twin spans bridge.
With an elevation of only a few feet above the normal level of the lake, Bosworth fears the area could go underwater in the late stages of an evacuation.
"There's a very, very vulnerable spot."
He acknowledges the skeptics, who find it difficult to believe the Army Corps of Engineers could fix a system that failed so miserably 10 ears ago.
"There was a lot of criticism after the storm of, 'Hey, the Dutch, a small country of 16 million people have these structures,'" Bosworth said. "'Why don't we have them?'"
He credits the world's civil engineering community with coming together to find solutions rather than Corps officials "suddenly open to suggestions."
The risk-reduction system does not eliminate the danger from hurricanes, but is designed to provide a level of protection against the 100-year storm. Corps computer models show some theoretical storms that would pack enough surge to top levees in the future.
However, Bosworth offers a generally glowing review of the work done over the last 10 years.
"I trust the system, and I'm the Corps' biggest critic," he said.