Popular Mechanics has an interesting special report, "Debunking the Myths of Hurricane Katrina," about popular misconceptions about the hurricane and its aftermath. PM notes that the rapid response by various levels of government was overshadowed by FEMA's lag; the hurricane itself was only a moderate storm, a category 3 at landfall, and the New Orleans floodwalls were, in fact, built properly. Good information here, including recommendedations for the future.
Most of the New Orleans floodwall failures occurred when water up to 25 ft. high overtopped the barriers, washing out their foundations. But three breached floodwalls--one in the 17th Street Canal and two in the London Avenue Canal--showed no signs of overtopping. Accusations of malfeasance were born after the Army Corps of Engineers released seismic data suggesting that the sheet-pile foundations supporting those floodwalls were 7 ft. shorter than called for in the design--a possible cause for collapse. In December 2005, PM watched Corps engineers pull four key sections of the 17th Street Canal foundation out of the New Orleans mud. The sections were more than 23 ft. long--as per design specifications. "I had heard talk about improper building before the sheet-pile pull," the Corps' Wayne Stroupe says. "But not much since."
