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Wednesday, September 21, 2005

Design Of Floodwall At Fault?

Via Lucianne.com. The Washington Post has an article today about the contention of experts that the two of the floodwalls that failed in New Orleans were not overtopped. They say that the Industrial Canal did succumb to the storm surge, but:
But the researchers have strong evidence that Katrina's subsequent surge from the north was several feet shy of the height that would have been necessary to overtop the 17th Street and London Avenue floodwalls. It was the failures of those floodwalls that emptied the lake into the rest of the city, filling most of New Orleans like a soup bowl.

On a tour Tuesday, researchers showed numerous indications that Katrina's surge was not as tall as the lakefront's protections. They showed a "debris line" that indicates the top height of Katrina's waves was at least four feet below the crest of Lake Pontchartrain's levees. They also pointed out how the breached floodwalls near the lake showed no signs of overtopping -- no splattering of mud, no drip lines and no erosion at their bases. They contended that the pattern of destruction behind the breaches was consistent with a localized "pressure burst," rather than widespread overtopping.
So what did cause the failures?
The center's researchers said it is too early to say whether the breaches were caused by poor design, faulty construction or some combination. But van Heerden said the floodwalls at issue -- massive concrete slabs mounted on steel sheet pilings -- looked more like the sound barriers found on major highways. He also suggested that the slabs should have been interlocked, and that the canals they were supposed to protect should have had floodgates to keep out water from the lake.

Former representative Bob Livingston (R-La.), who helped lead the charge for Corps projects in Louisiana when he chaired the House Appropriations Committee, noted that the earthen levees along Lake Pontchartrain had all held, while the concrete floodwalls had failed. He was especially concerned about the 17th Street barrier, saying it "shouldn't have broken."
All of which obviously raises the question of how safe similar floodwalls are. Whether it is construction or design, we don't know what happened and why. Rita is now officially a category 4 storm, although it is not as large as Katrina:
SATELLITE IMAGERY SUGGESTS THAT RITA HAS CONTINUED TO STRENGHTEN AND MAXIMUM SUSTAINED WINDS HAVE INCREASED TO NEAR 135 MPH WITH HIGHER GUSTS. RITA IS NOW A CATEGORY FOUR HURRICANE ON THE SAFFIR-SIMPSON SCALE. A NOAA PLANE WILL CHECK THE INTENSITY LATER THIS MORNING. SOME ADDITIONAL STRENGTHENING IS POSSIBLE DURING THE NEXT 24 HOURS.

HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 45 MILES FROM THE
CENTER...AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 140
MILES.
I hope the mayor is getting the word out in New Orleans. Texas is already evacuating Galveston.


Comments:
Billy Tauzon said this AM that 100 million was to go to an evacuation study and plans for NO.

Not only was that not done, it appears that no one knows where the money went.

That was in 1997.
 
Well, they did get more people out than they thought they could, so maybe some of it was used to do something worthwhile.
 
100 million buys a lot of buses.
 
"I hope the mayor is getting the word out in New Orleans."

I wouldn't trust this guy for anything. As far as I am concerned he is a liability that get's people killed.
 
They say Rita might be headed toward category 5 status. I hope they are going to clear out in LA. The projections are still showing 25-27% change of tropical force winds there.
 
The definitive answer (for now) here:

On the Levees of New Orleans: Update 12
 
Cool Blog, I never really thought about it that way.

I have a Hurricane Katrina blog. It pretty much covers hurricane related stuff.

Thank you - and keep up the thoughts!
 
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