Surge, breach and a 26-foot-deep gouge. The initial wave of storm surge that poured over the concrete wall of the 17th Street Canal as Hurricane Katrina passed New Orleans dug a 26-foot-deep gouge on the other side, resulting in the failure of several wall panels and the flooding of much of the city, an Army Corps of Engineers official said Thursday.
Al Naomi, project manager for the east bank Lake Pontchartrain hurricane levee system, said the high water that the strong Category 4 storm pushed into the lake overwhelmed the levee's design when the lake backed up into the canal.
"They were designed to withstand a surge for a Category 3 or less storm," Naomi said. "You might have had one or two feet of water pouring away over the top of the wall, cutting away at the earth below it, and as that happened, the walls began to collapse.
"When that occurred, there was no way to get water out of the city. Those walls are basically there, or they're not."
Naomi said corps engineers think the same thing happened along the London Avenue canal in Gentilly and along segments of the Inner Harbor Navigation Channel that gave way and flooded Chalmette. [Times-Picayune]