As the fifth anniversary of Hurricane Katrina looms, the noise of jackhammers, pile drivers and large-scale construction is as ever-present as the sound of New Orleans jazz or cicadas singing in Louisiana's August sun.

With a remarkable string of projects under way, totaling close to 15 billion dollars, the US Army Corps of Engineers is trying to protect the region from ever suffering such destruction again.

Colonel Robert Sinkler called it, "the largest project of its kind in the entire history of the Corps."

Sinkler commands the Corps' Hurricane Protection Office and is part of the leadership team responsible for constructing the Hurricane and Storm Damage Risk Reduction System for the greater New Orleans area.

This defense system is complex, including 350 miles (560 kilometers) of levees and flood walls combined with 78 pumping stations and numerous emergency flood gates to help seal the perimeter of the low-lying city and its surrounding areas in the event of a major storm.

"We're delivering some pretty big projects," Sinkler said. "We're looking to complete 15 to 20 years worth of construction in about six months."

The anniversary on Sunday of Katrina, which killed more than 1,500 people when the levees broke, has placed the enormous job of protecting this region from future flood disasters under the microscope.

As resilient Louisiana residents rebuild their homes and neighborhoods, many still don't place their confidence in a federal agency they feel failed them in what many consider the worst civil engineering disaster in US history.

"Relying on the Corps is not an option," said Sarah DeBaucher, vice president of the Holy Cross Neighborhood Association, located in the now-infamous lower ninth ward which suffered some of the worst of the flood damage and loss of life.

"We bought our new house on high ground, with pilings," said DeBaucher, who moved with her husband to the neighborhood after the flood and has been active in local rebuilding efforts.

They work alongside local and national organizations, including actor Brad Pitt's "Make it Right" Foundation.

DeBaucher regularly attends the community meetings with Corps representatives and finds herself generally frustrated and distrustful of the process.

"They pay a lot of lip service to community involvement, but when they finally reply to our comments or concerns it's buried in a 100-page document and written in legalese," she said.

"When only 55 percent of the neighborhood is back and we're all trying to rebuild our houses and lives, who has time for that?"

Jarret Lofstead, a local business owner and editor of NOLAFugees.com, wasn't surprised to hear of the lingering skepticism.

Lofstead spent months alongside his business partner rebuilding his downtown bar and restaurant after floodwaters receded, leaving it a garbage-strewn, mud-caked wreck.

"I'll tell you what's different about the city," he said, reflecting on the five-year anniversary.

"Everything we ever took for granted in New Orleans is now gathered under this one banner, the fleur-de-lis," he said, referring to the symbol of grassroots support for New Orleans's recovery.

"We have forged a cultural identity that we didn't have before, bringing all these disparate elements together."

But beneath the surface of this new cultural solidarity though, Lofstead saw the exact same social dynamics that have been the root of so much suffering in New Orleans are still there.

"It's the same failing schools," said Lofstead. "It's the same crime rate. It's the same inefficient justice system. If you look at the levees, the Army Corps has made all these developments, but no one really knows if they're going to work."

"All the optimistic predictions for New Orleans haven't been proven. I'm waiting to see if any of it sticks."

Sandy Rosenthal, executive director of recovery group Levees.org, agreed there was a long way to go despite the massive financial commitment of the federal government. "Are we safer than we were before? Not yet," she said.

Many of the Corps' large projects aren't scheduled to be completed until June 2011, but what really drives Rosenthal's skepticism is the Flood Control Act of 1928 which provides legal immunity to the Corps for any failures in their engineering works, no matter how catastrophic.

Indeed, it's the very act that was cited in the 2008 US district court ruling to dismiss the Katrina-related class action lawsuit against the Corps. "There's no accountability," Rosenthal said.

"There has never even been an independent investigation into what caused the 2005 failures. And when you consider that 55 percent of the US population lives in levee-protected areas, you realize this is not just a New Orleans issue - this is a national issue."