Storm Surge Barrier Going Up to Protect New Orleans

It is unusual for a civil works project to be designed and constructed simultaneously, but the Corps says the expedited process is necessary given the compressed timeframe to achieve 100-year flood protection in 2011.

When completed, the $700 million surge barrier, similar to a floodwall but much larger, will run for nearly two miles near the confluence of the Gulf Intracoastal Waterway and the Mississippi River Gulf Outlet. The 26 foot high barrier will run north-south from a point just east of Michoud Canal on the north bank of the waterway and just south of the existing Bayou Bienvenue flood control structure.

Navigation gates will be constructed where the barrier crosses the GIWW and Bayou Bienvenue to reduce the risk of storm surge coming from Lake Borgne and/or the Gulf of Mexico. The openings for each gate will be 150 feet wide.

Another navigation gate is planned for the Seabrook vicinity where the Inner Harbor Navigation Canal meets Lake Pontchartrain to block storm surge from entering the canal from the lake.

Confluence of the Mississippi River Gulf Outlet, left, and the Gulf Intracoastal Waterway (Photo courtesy USACE)

The surge barrier is a new feature, authorized by Congress in 2006, the year after hurricanes Katrina and Rita devastated the area. It is expected to reduce the risk of storm damage to some of the region's most vulnerable areas - New Orleans East, metropolitan New Orleans, the 9th Ward, St. Bernard Parish and Gentilly - to a one percent chance in any given year.

"This is territory we must defend, and we must defend it with all of our ingenuity, and with all of our strength, and with all of our determination, and with every fiber of our being," said John Paul Woodley, assistant secretary of the Army for public works, during the floating groundbreaking ceremony December 5. It was attended by more than 100 people aboard an Army Corps of Engineers enclosed barge towed to the construction site.

"To achieve these project goals, the Corps, the state, our local partners and the local communities must all work together. It's all about teamwork," said Karen-Durham-Aguilera, the Corps' Task Force Hope director.

Advance measures will provide some protection for the area in 2009 although the barrier is not expected to be complete until 2011.

The advanced measures include a concrete barrier and a swinging navigation gate on the Gulf Intracoastal Waterway that would allow navigation to bypass the construction of the concrete floodwall and at the same time provide protection from surges.

Additionally, temporary retaining structures called coffer dams would be built at both the Gulf Intracoastal Waterway bypass swing gate and the location of the Bayou Bienvenue gate to provide risk reduction until the gates are complete.

A second level of risk reduction in the short term will be achieved by installing concrete caps on top of the concrete barrier, which will raise the level of the barrier to 20 feet.

For a separate project that is also aimed at reducing flood risk in the New Orleans area, the Corps is overseeing the $13.6 million Mississippi River Gulf Outlet closure structure.

The Mississippi River Gulf Outlet is a former federal navigation channel opened in 1968 to provide a short route between the Port of New Orleans and the Gulf of Mexico. On August 29, 2005, Hurricane Katrina made landfall in the area, causing widespread property and environmental damages. Since the storm, the shipping channel has not been maintained although navigation has continued.

On December 16, the Corps issued a Notice to Proceed to the construction contractor, Pine Bluff Sand and Gravel Company of Pine Bluff, Arkansas. The contractor will dump 430,000 tons of rock across 10 acres of water bottom.

Building the structure will end more than 45 years of navigation on the recently de-authorized federal navigation channel.

"The Corps of Engineers and the State of Louisiana are working faster than ever to provide protection to New Orleans and St. Bernard Parish by cooperating in the building of a surge barrier for the Inner Harbor Navigation Canal and closing the Mississippi River Gulf Outlet," said Coastal Protection and Restoration Authority Chairman Garret Graves. "This shows what our partnership is capable of accomplishing and hopefully the kind of pace we will continue to take when building other restoration and protection projects."

Since Hurricane Katrina flooded New Orleans when levees gave way, Corps leaders have pledged to provide the region with protection from a 100-year storm surge by the start of the 2011 hurricane season or "break our backs trying." A banner draped across the Corps headquarters' entrance in New Orleans announces the pledge.

To do that, the Corps and its consultants are designing hundreds of upgrades along the entire 350-mile levee system, including raising the height of the lakefront levee across Metairie and Kenner.

Future work in the area will include other coastal wetlands restoration projects. As organic material is dredged from waterways in preparation for new construction, it will be deposited in nearby wetlands habitat to enhance environmental conditions.

The Corps is working closely with federal and state partners to produce a supplement to the Mississippi River Gulf Outlet closure plan that will address ecosystem restoration in areas affected by the MRGO channel. Potential plan features may include marsh creation, shoreline protection, barrier island rebuilding, and freshwater diversions from the Mississippi River.

Copyright Environment News Service (ENS) 2008. All rights reserved.