Design Flaw Led to New Orleans Levee Breach

New Scientist, 18 Mar 2006 We now know how it happened, but whether it could have been prevented is still hotly disputed. The US Army Corps of Engineers has acknowledged for the first time that the New Orleans 17th Street Canal levee was breached during hurricane Katrina because of a failure in the system, rather than because the storm exceeded the levee's design specification. On 10 March, the corps released an interim report saying the levee split in two when its steel-supported concrete walls tilted. That, and a weak layer of clay in the soil near the edge of the levee, caused a 60-metre-long portion of the barrier to slide forward and break away. However, Ivor van Heerden of the Louisiana State University Hurricane Center in Baton Rouge insists that the corps knew about the weak layer of soil, having discovered it in borehole samples taken in 1982. Other scientists say the sliding action of the levee was also documented in the 1980s, after tests carried out by corps's engineers.