London Avenue Canal Levee Breach in 2005
Text
In 1965, Hurricane Betsy demonstrated that a major hurricane could overtop the earthen levees of the London Avenue Canal. So the Army Corps of Engineers recommended two plans -- raising the height of the canal walls using concrete-capped steel sheet pilings (I-walls) or installing floodgates at the canal's mouth at the lakefront. The Corps felt both alternatives provided equally sufficient storm surge protection.
Since raising the heights of the walls was three times more expensive than the floodgates plan, the Corps recommended the latter. The Corps believed it was following its congressional mandate. Unlike the ones built post-Katrina, these original gates did not include auxiliary pumps.
Meanwhile, the Orleans Levee Board (OLB) and the Sewerage and Water Board (S&WB) legitimately feared that the cheaper gates-only plan was incompatible with their interior drainage responsibilities. So, in 1991, in full transparency, the OLB, backed by the New Orleans City Council, the S&WB, and neighboring communities, asked the state congressional delegation for authorization for the much more expensive higher flood walls plan. They succeeded, and the corps installed the new I-walls.
Before the 2005 flood, the adjacent area to the breach site was a thriving mixed neighborhood of white and African American homeowners. Homes were shaded by oak, cypress and pecan trees.
On August 29, 2005, at about 9:30 a.m, two monoliths (30-foot long sections of concrete floodwall) failed, sending torrents of water and sand into New Orleans's Gentilly neighborhood. The location was the 4900 block of Warrington Drive. At failure, the water level in the canal was about 5 feet lower than the top of the wall. Storm surge water poured through the gap, killing hundreds (directly and indirectly), destroying hundreds of residences, and causing millions of dollars in property damage.
Today, the adjacent land is largely vacant of homes, buildings and trees. Many foundations or slabs where homes once stood are all that remain. The repaired breach site now consists of a different sturdier design called a T-wall. Three times more expensive to build, the new wall is easily differentiated because of its different texture and color.
Post-disaster studies concluded that the breach occurred due to steel sheet pilings driven to depths that were too shallow. Sadly, in recommending the I-walls with such short sheet pilings, the Corps had relied upon a poorly executed and misinterpreted study it had conducted near Morgan City in 1988. At a savings of $100,000,000, the Corps wrongly concluded it could "short-sheet" the steel pilings of the 17th Street Canal driving them to depths of not more than 17 feet instead of between 31 and 46.
In January 2008, Federal Judge Stanwood Duval, of the US District Court for Eastern Louisiana, held the US Army Corps of Engineers responsible for defects in the design of the concrete floodwalls constructed in the levees of the London Avenue Canal; however, the agency could not be held financially liable due to sovereign immunity provided in the Flood Control Act of 1928.
