U.S. Army Corps of Engineers project manager Jason Ragolia knew his team had to stay focused to deliver 100-year storm protection in record time to the residents of New Orleans, Louisiana, USA. So he put a mantra on his office wall: We all want to be rowing in the same direction. It was an apt metaphor for the historic task that lay ahead: building a barrier to stop storm surges from advancing farther inland from the Gulf of Mexico and wreaking havoc on New Orleans and its environs, as waters stirred up by Hurricane Katrina did in 2005.
The fast-track Lake Borgne Surge Barrier (LBSB) project was the largest design-build effort in the Army Corps of Engineers’ history. Constructed in just three years at a cost of US$1.3 billion, the 1.8-mile-long (2.9-kilometer-long) barrier rises 26 feet (8 meters) above the normal water line, making it the tallest barrier of its kind in the world.
Construction of the Lake Borgne Surge Barrier
“If the Lake Borgne Surge Barrier had been a traditional big-build project, we'd still be out on Lake Borgne right now.”
—Jason Ragolia, U.S. Army Corps of Engineers, New Orleans, Louisiana, USA
The project faced two major challenges. The first was keeping workers safe on the open-water construction site; due to erosion, Lake Borgne is actually a lagoon directly connected to the Gulf of Mexico. The second was meeting a deadline imposed by the U.S. Congress. A design-build approach allowed for an intensely condensed schedule and proved key to its success.
“If LBSB had been a traditional big-build project,” Mr. Ragolia says, “we'd still be out on Lake Borgne right now.”
Hands-On Budgeting
Beginning in 2005, the U.S. Congress allocated US$14.6 billion for a comprehensive hurricane and storm damage risk reduction system to protect New Orleans—including US$1.4 billion for the LBSB project. Though construction wouldn't be completed until 2012, Congress mandated that the project had to be able to protect against 100-year storm surges by 2011.
Army Corps projects have often been incrementally funded, leading to lost time and wasted money as construction is delayed and already-built structures have to be re-evaluated, Mr. Ragolia explains. The fact that the project was fully funded from the outset and received steady support from two successive U.S. presidential administrations proved crucial for delivering the expedited project on time.
In April 2008, the Army Corps awarded general contractor Shaw Group (later acquired by Chicago Bridge and Iron) the project on a cost-reimbursable basis. Rather than giving Shaw Group a lump sum of money, the Corps reviewed the company's materials, labor and equipment costs to ensure it was spending wisely and “not making bad decisions just because they're easy,” Mr. Ragolia says. “We were very involved with the decision-making process that way.”
In December 2013, when the Army Corps handed the new facility off to the State of Louisiana to manage, the LBSB's final cost was US$1.3 billion—US$100 million under budget.
Crews construct the barge for the surge barrier.
Precast concrete was used, since it could more quickly be created off-site and then transported via barge.
Responsive Design
After one year in the initial design phase, in May 2009 Mr. Ragolia and his team drove the first of several concrete piles into Lake Borgne to serve as the barrier's foundation. Initially, planning engineers were tempted to dump a bunch of stone in the lake and build a run-of-the-mill levee. (Levees are earthen structures, while barriers are typically concrete.) But with the 2011 milestone looming, the team arrived at the idea of a precast mold for the barrier since it could more quickly be created off-site and then transported via barge. Getting the barrier's biggest component into the ground as quickly as possible ultimately saved months, Mr. Ragolia notes.
To support the Shaw Group, three subcontractors were brought in. “Equipment, manpower, management—each had their own expertise,” Mr. Ragolia says.
“We were changing the design as we were building. We would find a condition where we needed to change alignment or create a more robust foundation.”
—Jason Ragolia
Racing Against Time
Creating a storm surge barrier providing a 100-year level of risk reduction normally requires 10 to 15 years to design, obtain permits and construct. But after its levee system failed to stand up to Hurricane Katrina's storm surges, the New Orleans region didn't have that kind of time. More hurricanes would be on their way.
The project's four-year schedule, covering construction and hand-off to the state, was executed against three major deadlines. One-hundred-year level protection through manual control had to be achieved by June 2011 (the “interim project completion” deadline). The barrier had to perform by the push of a button by December 2012. Finally, the Army Corps had an end-all project date, to hand over operations to the State of Louisiana's Coastal Protection Restoration Authority Board, by December 2013.
The gates at the surge barrier were installed over several days.
Hot, Humid and Vulnerable
Given that the entire construction process was taking place in and above water, project safety took center stage. “Nobody could get complacent,” Mr. Ragolia says. “It was heavy construction for about three years; a lot of the materials were over 100 tons.” Engineers had to consider, for example, how such heavy objects might impair a crane operating on a barge.
Louisiana's notoriously hot and humid summer weather was another safety factor to consider in work shifts. “We built some of the barrier components and three major gates in a coffer dam”—a watertight enclosure pumped dry to permit construction below the water-line—“so there was no air movement,” he says. “That heats things up pretty fast.”
The project team set up three daily shifts so that work progressed around the clock without compromising safety.
The U.S. Army Corps of Engineers closed the barrier for the first time during a storm in August 2012.
PHOTOS COURTESY OF U.S. ARMY CORPS OF ENGINEERS
Mother Nature's Test
In August 2012, the barrier went head-to-head with Hurricane Isaac. “Most components were done, but it was a real test,” Mr. Ragolia recalls.
The LBSB passed: The Army Corps closed the barrier's gates, as well those in another surge barrier in the area, to stop a 15-foot (4.5-meter) surge of sea water that otherwise would have funneled its way toward New Orleans.