New Orleans preparing for hurricanes By John Hall

New Orleans District

A weather satellite photo shows the classic shape as well as the size and power of hurricane Elena in 1985.  The hurricane ravaged the Gulf states and caused severe coastal erosion.  The LAke Pontchartrain and Vicinity Hurricane Protection Project in New Orleans is designed to reduce such damage in the future (Photo courtesy of NASA)

New Orleans District recently began rebuilding bridges to improve hurricane protection in New Orleans' Lakeview section. This will permit vital roadways, now sandbagged during a storm, to remain open. Last year was the biggest year for flood-proofing in the area, with construction beginning on five bridges. In all, 10 bridges will be floodproofed along three drainage canals in Orleans and Jefferson parishes (counties). Total cost will be about $25 million. Floodproofing bridges is an indispensable portion of the ongoing $739 million Lake Pontchartrain and Vicinity Hurricane Protection Project.

The London Avenue Canal Bridge is being replaced as a flood-proofing measure. (Photo by Michael Maples, New Orleans District)

It is being built by the U.S. Army Corps of Engineers and four levee boards in Orleans, Jefferson, St. Bernard, and St. Charles parishes.

In floodproofing, the original bridge is demolished. Each replacement bridge will have steep, concrete sides to continue the floodwall from one side of the canal to the other. Two of the Lakeview bridges, on Filmore and Harrison Avenue, span the Orleans Avenue Canal, which lies between Lakeview and City Park. Angelo Iafrate Construction has a $2.36 million contract for the two-lane bridges.

"We're asked why we are replacing these bridges, just four blocks apart, at the same time," said Col. William Conner, New Orleans District commander. "The answer is that we have coordinated this work with the neighborhoods and City Hall. They don't want to go through any more hurricane seasons than they have to without floodproofing. This is an encouraging sign that people are taking the hurricane threat seriously."

Floodproofing is vital, said Al Naomi, New Orleans District's senior project manager for the Lake Pontchartrain and Vicinity project. "The new bridges are final links in the chain of protection provided by hurricane levees and floodwalls. Besides keeping water out, we want to keep roadways open. The roadways' value becomes clear when evacuation is required as a hurricane is approaching."

The Orleans Levee District and the East Jefferson Levee District are the local sponsors with the Corps for floodproofing the bridges.

Demolishing existing bridges is required for floodproofing in order to deal with hurricane storm surges, said Kevin Wagner, the Corps' project manager for the Lake Pontchartrain and Vicinity project.

"There's a buoyancy problem," Wagner said. "We want to keep these bridges from popping out if the water rises around them, so we're providing new pilings with the strength to anchor them properly."

Once construction is complete, the levee districts take over operation and maintenance of the hurricane-protection projects. The levee districts must begin sandbagging and closing floodgates about 36 hours before a hurricane's arrival. Floodproofing the bridges will allow the levee districts to shift their work forces, always stretched thin during storms, to other essential tasks.

The cost of floodproofing varies with each bridge. C.R. Pittman has a $3.33 million contract for a four-lane bridge now under construction, on Gentilly Boulevard over the London Avenue Canal in New Orleans. Last summer, work began on the four-lane Leon C. Simon Boulevard bridge over the London Canal in New Orleans. Miller Excavating has the $3.86 million contract.

All four bridges begun in 1999 are expected to be finished in a few months. A fifth bridge has already been complete, leaving five to go.

Construction is expected to begin this year on four more bridges. One will increase the capacity of a busy roadway linking New Orleans and Metairie at Lake Ponchartrain. A four-lane bridge will replace the two-lane bridge on Old Hammond Highway over the 17th Street Canal.

Source: http://www.hq.usace.army.mil/cepa/pubs/mar00/story3.htm