International Dredging Review

International Dredging Review
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A construction kick-off ceremony was held on the Mississippi River Gulf Outlet on Thursday December 11. Defense of the Greater New Orleans’ most vulnerable area from storm surge began Thursday December 11 with the groundbreaking of the Inner Harbor Navigation Canal (IHNC) Lake Borgne Surge Barrier Project.

Approximately 200 local residents political leaders and Corps officials celebrated the start of the largest design-build civil-works project in the Corps’ history aboard a Corps inspection barge anchored near the middle of the two-mile-long project 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 the Corps’ Task Force Hope Director Karen Durham-Aguilera.

The IHNC Surge Barrier Project is a significant piece of the Hurricane and Storm Damage Risk Reduction System (HSDRRS) because it will block the powerful Gulf of Mexico storm surge from entering the Gulf Intracoastal Waterway (GIWW).

When completed in 2011 the $700 million surge barrier will extend from the Michoud Canal floodwall along the GIWW to the Mississippi River Gulf Outlet (MRGO) levee just south of the Bayou Bienvenue control structure. It will reduce the hurricane and storm surge risk faced by the people in the surrounding communities of St. Bernard New Orleans East Ninth Ward and Gentilly to a one percent chance in any given year.

“When we see this surge barrier we will know that it is a stance we’ve taken for the betterment of the people in New Orleans” said Army Corps of Engineers Commander Lt. Gen. Robert Van Antwerp. Six features make up the IHNC Lake Borgne Surge Barrier Project. The GIWW features include the GIWW north floodwall the GIWW gates and the GIWW to Bayou Bienvenue floodwall. The Bayou Bienvenue features include the Bayou Bienvenue gate and the Bayou Bienvenue to MRGO south floodwall. The final feature of the barrier is the MGRO south floodwall.

The Corps awarded the IHNC Lake Borgne Surge Barrier contract to Shaw Environmental & Infrastructure of New Orleans Louisiana in April 2008. Shaw has completed nearly 50 percent of the design for the project.

The Corps and Shaw estimate that construction will require approximately 57000 tons of steel 2600 closure piles and 1300 concrete vertical piles approximately 5½ feet in diameter and 144 feet long each weighing 92 tons.

Additionally 660 steel batter piles 36 inches in diameter will provide support for the structure The initial barrier standing over 14 feet high will provide advance measures.

Later 300 deck sections 17 feet long 12 feet wide and six feet high each weighing 96 tons will sit on top of the main surge barrier. The deck sections will bring the height of the barrier to 20 feet above water. Crenels and merlons added to the decks a feature giving the barrier the appearance similar to the open and closed spaces on battlement fortifications in castles will bring the total height of the structure to 24 and 26 feet.

The Corps expects to complete the IHNC Lake Borgne Surge Barrier in 2011 with advance measures put into place during hurricane season in 2009.