A mammoth construction project by the Army Corps of Engineers to build a 10-foot tall flood protection wall across Causeway Boulevard in Metairie will begin spring 2010, a feat that puts the final stamp on the Corps’ goal to finish its 100-year risk reduction plan, a project manager said.

The wall, spanning up to 1,200-feet long, will connect two levees when finished before the 2011 hurricane season, Project Manager Rebecca Constance said at a public meeting Tuesday night at Church of the King Church in Mandeville.

Going out to bid in January 2010, Corps officials anticipate costs to run between $5 million and $20 million, in part because engineering plans also call for a second project phase finished by 2012 –a portion of the Causeway elevated above the floodwall. Both projects will have minimal traffic delays, Rene Poche, public affairs officer for the Corps, said Starting 500 feet from the southbound shoreline, the bridge will be elevated above the floodwall and connect back to the ground on Causeway Boulevard near Sixth Street, Poche said. When finished, the bridge will extend roughly 1,000 feet further south and boast four new exit and entrance lanes in both directions. Like the Northshore toll traffic, the four lanes will eventually converge into two lanes, he said. The Southshore toll office, built in 1956 and home to the Causeway Police office, is slated for demolition.

On the Southshore, commuters exiting Fifth Street in Metairie will no longer be able to turn onto Causeway Boulevard. Miniscule delays are expected for other commuters, Poche said.

Two lanes of traffic — entering and exiting — will always be open during construction, Poche said.

“There may be a little backup but hopefully not past W. Esplanade,” he said.

The project is considered a feather in the cap of Corps officials who since Hurricane Katrina in 2005 have scampered to engineer and build flood protection along the Southshore shoreline to withstand a catastrophic storm event that occurs every 100 years. Already, Corps officials have held 147 public meetings for this project alone.

Environmental impact studies were conducted, public input was weighed and engineering blueprints were drafted and rewrote. Causeway Commission Executive Director Carlton Dufrechou said the final product is literally lifesaving.

Because the bridge will be elevated above any storm surges, “first responders can get back immediately,” he said. “That is as significant as the floodwall itself.”

The elevated bridge also allows the bridge to stay open longer when a hurricane threatens, allowing last minute evacuees to jettison to safety.

The bridge would “be open till the storm is breathing down our throats,” Dufrechou said.