IHNC Lake Borgne Surge Barrier
|Inner Harbor Navigation Canal Lake Borgne Surge Barrier|
|Locale||New Orleans, Louisiana|
|Owner||US Army Corps of Engineers|
|Total length||1.8 miles|
|Construction end||2013 (major construction)|
|Construction cost||$1.1 billion|
The Inner Harbor Navigation Canal Lake Borgne Surge Barrier is a storm surge barrier constructed near the confluence of and across the Gulf Intracoastal Waterway (GIWW) and the Mississippi River Gulf Outlet (MRGO) near New Orleans. The barrier runs generally north-south from a point just east of Michoud Canal on the north bank of the GIWW and just south of the existing Bayou Bienvenue flood control structure. Navigation gates where the barrier crosses the GIWW and Bayou Bienvenue reduce the risk of storm surge coming from Lake Borgne and/or the Gulf of Mexico. Another navigation gate (Seabrook Floodgate) has been constructed in the Seabrook vicinity where the IHNC meets Lake Pontchartrain to block a storm surge from entering the IHNC from the lake.
The Inner Harbor Navigation Canal (IHNC) surge barrier was authorized by Congress in 2006. The barrier is designed to reduce the risk of storm damage to some of the region's most vulnerable areas - New Orleans East, metro New Orleans, the 9th Ward, and St. Bernard Parish. This project aims to protect these areas from storm surge coming from the Gulf of Mexico and Lake Borgne.
The project was funded by the American Recovery and Reinvestment Act of 2009. In April 2008, the Corps awarded a construction contract to Shaw Environmental & Infrastructure for the Lake Borgne Surge Barrier, making this project the largest design-build civil works project in Corps history. It is highly unusual for a civil works project to be designed and constructed simultaneously. The expedited process is necessary, however, given the compressed timeframe to achieve 100-year level of risk reduction in 2011.
In October 2008, the New Orleans District Commander signed the Tier 2 portion of the Individual Environmental Report (IER), which investigated alternative alignments and designs within the location range identified by Tier 1 and explained the impacts of these alignments and footprints, construction materials and methods, and other design details. After the completion of the IER, a Notice to Proceed was issued to Shaw.
In December 2008 the Corps held a groundbreaking ceremony to mark the start of test pile driving. Construction of the barrier floodwall began on May 9, 2009. On 21 October 2009 the last of the 1,271 main piles was driven.
The main barrier consists of 1,271 concrete piles 66 inches (1.7 m) across and 144 feet (44 m) long, weighing 96 tonnes each. Behind those piles, steel piles 288ft long in 2 sections 1st section 158ft in length is pile driven into place. The second section 130ft length is fitted on top and welded together. The piling is driven at 33 degrees to vertical or 57 degrees from horizontal onto its final place . On top of these pilings prefabricated concrete sections are placed.
In the Gulf Intracoastal Waterway navigation channel there are two gates constructed. One gate is closed with two sector gate leaves, the other gate with a barge swing gate, comparable to a caisson. In the Bayou Bienvenue navigation channel there is a vertical lift gate for recreational craft and shrimpers.
- Typical flood wall and the MRGO closure flood wall (over a mile long)
- 150-foot wide navigable floodgate on the GIWW—a steel sector gate (42 feet tall)
- 150-foot wide navigable bypass floodgate on the GIWW—a concrete barge swing gate
- 56-foot wide navigable floodgate on Bayou Bienvenue—a steel lift gate
- Concrete T-walls on land, at the north and south ends of the Lake Borgne barrier
- Approach walls at the GIWW sector gate and the Bayou Bienvenue gate
- Navigation gate in the Seabrook vicinity
- Marsh enhancement with dredged organic material - As organic material is dredged from waterways in preparation for new construction, it will be deposited in nearby wetlands habitats to enhance environmental conditions
|Wikimedia Commons has media related to IHNC Surge Barrier.|
- "IHNC Lake Borgne Surge Barrier". U.S. Army Corps of Engineers. June 2013. Retrieved December 12, 2013.
- 1.1 billion surge barrier construction works half way
- Architings.com:Shaw Makes History with Major Milestone at World’s Largest Surge Barrier in New Orleans
- Corps Closes More Floodgates as Hurricane Isaac Approaches