Storm Surge Defense
Eight pumps with a capacity totaling 13,920 cu ft per second were put through their paces on June 3, demonstrating that the $1-billion Gulf Intracoastal Waterway West Closure Complex near Harvey, La., is ready for operation this hurricane season.
The complex consists of operating gates, t-walls and levees that are designed to close up as a barrier to reduce the impact from a 100-year storm surge entering the Harvey and Algiers Canals on the West Bank of the Mississippi River in Greater New Orleans. The pump complex, which is the largest interior drainage pump station in the world, will evacuate stormwater that would otherwise build up behind the barrier and flood areas of the city when the gates are closed.
By Aug. 1, the U.S. Army Corps of Engineers plans to have the last three 1,740-cfs pumps running, reaching full capacity and “exceeding expectations for this hurricane season,” says Kevin Wagner, the Corps project manager.
The closure complex is one of the largest, most complicated facilities in the $14.6-billion Greater New Orleans Hurricane and Storm Damage Risk Reduction System. Build-out of the city's perimeter protection system, which had been constructed piecemeal for more than 50 years, was fully funded by Congress after Hurricane Katrina in 2005. Congress set the the start of the 2011 hurricane season, which began on June 1, as the deadline for raising protection to the level of a 100-year storm.
In addition to including the massive 19,140-cfs pump station, the complex also has the world's largest sector gate with a width of 225 ft. Together with its sluice gates, walls and levees, the complex features every aspect of a Corps civil works project, says Col. Ed Fleming, commander of the New Orleans District.
“West Closure Complex has a little bit of everything—dredging, 404C [environmentally sensitive wetlands], sluice gates, earthen levees, pumps and navigable gates,” Fleming says, adding that the complex takes perimeter defense “out of people's backyards” by eliminating 26 miles of existing walls and levees, much of it lining canals running deep into the city. It also “demonstrates what we can do with a fully funded civil works program,” Fleming says.
The Corps initially planned to demonstrate the pumps in a “wet test” in mid-April, but it had to make modifications on the custom pumps when an upper bearing overheated and cracked during trials, Wagner says. “After the first one cracked, we set parameters of temperatures much lower on the next two pumps. When we started seeing increases in temperatures with the other two pumps, we decided we had to rebore the bearings.”
Despite 1:15 and 1:22 scale model tests performed at the Corps' Engineering Research & Development Center in Vicksburg, Miss., last summer, the Corps expected to need field modifications because everything was custom built, Wagner says. “We modeled to ensure they would work, and to make sure the velocities weren't too high for navigation,” he says, “but the modification of these bearings was very exact.”
The contractor, Gulf Intracoastal Constructors, a joint venture of Kiewit Corp., Omaha, Neb., and Traylor Bros. Inc., Evansville, Ind., made modifications with pump manufacturer Fairbanks Morse, Beloit, Wis., and MR Pittman Group LLC, New Orleans, at nearby Bollinger Shipyards.