New Orleans has a better defense should another big storm hit the city. But it’s never going to be completely safe.
“You can’t eliminate risk no matter where you are,” said Jo Ellen Darcy, assistant secretary of the Army for Civil Works, at a March 22 press conference in New Orleans.
“What we are doing here is buying down the risk, buying it down to that 100-year level,” she said.
Darcy spoke at the site of the soon-to-be-completed, $1-billion Gulf Intracoastal Waterway West Closure Complex in Belle Chasse, La. It is one of the major components of the $14.6-billion civil works program being delivered by the U.S. Army Corps of Engineers in the greater New Orleans area to reduce risk of flooding from storm surge events that have a 1% chance of occurring in any given year.
“I won’t say protected, but your risk is greatly reduced for a 100-year event,” said Lt. Gen. Robert Van Antwerp, chief of engineers and commanding general of the Corps.
Residual risk was the over-riding message the officials delivered, against the backdrop of the central feature of the West Closure Complex—the largest interior drainage pump station in the world—and during the final weeks of construction of the largest civil works program in the history of the Corps.
“We have multiple lines of defense on a lot of our projects, whether they be ecosystem restoration or risk reduction projects of levees and floodwalls,” said Col. Edward Fleming, commander of the Corps’ New Orleans District.
“There is always going to be a residual risk, so what you need to do is have a plan in place�.a full tank of gas, and an evacuation plan. And you have to listen to your elected officials because when they say it’s time to evacuate, evacuate, because there is always going to be some residual risk.”
The other message at the press conference was that the Corps has largely delivered on what Van Antwerp promised in May, 2007: to bring the 350-mile-long system of defenses to 100-year levels by the start of hurricane season on June 1, 2011, or “break our backs trying.”
Projects are coming to completion throughout the system.
Gulf Intracoastal Constructors, a joint venture of Kiewit Corporation, Omaha, Neb. and Traylor Bros., Inc., Evansville, Ind. began construction of the GIWW WCC in August 2009 and it is nearly 71% complete.
The combination surge barrier/drainage evacuation complex will provide the first line of defense from storm surge entering the Harvey and Algiers Canals on the west bank of the Mississippi River. WCC includes floodwalls, sluice gates, foreshore protection, an earthen levee, and the drainage pump station.
The concrete building housing the pumps is 608 ft long and the roof is at +86 ft elevation. The 19,140 cu.-ft.-per-second pump station includes 11 flowerpot pumps with 1,740 cfs capacity each. “The discharge flume is at +11 ft, and a lip above that is at +14 ft,” says Bob Ivarson, practice director, water resources for HNTB Corporation, Kansas City, Mo., the technical lead on pump station design.
HNTB is providing ongoing engineering during construction and hopes success on this project will influence selection on the Corps’ estimated $800 million, design-build award in late April for permanent pump stations at New Orleans’ three outfall canals. “We are on a team with Weston [Solutions, Inc., West Chester, Penn.], and we have a successful design,” Ivarson says.
Two, 750-ton steel leaves of a 225-ft.-wide sector gate were placed March 6 and March 10. Work inside the pump station is mostly electrical and mechanical at this point, says Kevin Wagner, Corps project manager. The contractor is “running wires for building lighting, wiring for engines, generators, control panels and operating room,” Wagner says.
Mechanical activities include: leveling, aligning, and attaching the engines to gear reducers, as well as attaching intake and exhaust mufflers. Piping is being installed for wastewater, HVAC and keel coolers. Keel coolers are piping units to keep the engines at an acceptable temperature when the pumps are on.
“They are essentially large scale radiators and are located in the discharge chambers at elevation +11 ft,” Wagner says. “The next milestone at WCC will be the wet testing of the pumps, which is on schedule for mid-April.”
Despite the timely delivery by the Corps, concern remains over how local stakeholders will meet the estimated $5 million operations and maintenance costs for the system, as well as who will bear the cost of adding future lifts to earthen levees to keep pace with subsidence.
“These projects are built to go the distance to 2057 and beyond,” Van Antwerp says, but local sponsors are responsible for operations and maintenance. Nor does Congressional authorization and program funding for the system provide for future lifts, says a Corps spokesperson. “We anticipate that future levee lifts will be needed after the system is completed,” she says. “Future investments by the federal government would require new Congressional authorization and appropriated funding.”
Darcy says the Corps’ new water-resources “Principles and Guidelines” will be out this summer.
Van Antwerp adds that the Corps does nothing without federal authority, funding and appropriations. The program in New Orleans was delivered quickly and efficiently because full-funding made it possible to use alternative delivery methods like design-build and early contractor involvement. “Most civil works funding is on an annual basis, so it’s not as effective as if you had all the money,” Van Antwerp says.