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Hurricane Gustav lashed the Gulf Coast with wind and rain Monday. Experts examine the region's preparedness for the storm, three years after Hurricane Katrina.
Now, more on how prepared was the Gulf Coast for a major storm three years after Katrina. Margaret Warner has our story.
And for that, we turn to Michael Greenberger, director of the Center for Health and Homeland Security at the University of Maryland; and Major General Don Riley, deputy commander of the U.S. Army Corps of Engineers. He's been deeply involved in the Corps' ongoing reconstruction of the levees and floodwalls in the gulf region.
And welcome to you both.
General Riley, Tom Bearden filed that report a short time ago. What's the absolute latest? Are all the levees and floodwalls holding?
MAJ. GEN. DON RILEY, U.S. Army Corps of Engineers: In New Orleans proper, in the city, they are holding. What we don't know is the condition of those levees outside of New Orleans, especially down in Plaquemines Parish, and west over in Lafourche Parish, and Houma, and Morgan City.
Now, the levees in New Orleans that are holding, despite the water overtopping them, why is that? They didn't hold last time. Is that because these — the ones under pressure now are the ones you've rebuilt? Or is it simply that the storm is less intense?
MAJ. GEN. DON RILEY:
The ones you saw today on the news and what they just showed, those are the ones that we replaced along the Inner Harbor Canal. And some we replaced; some we repaired.
But those that have been replaced, they have been built to be more resistant to scour. They've been built with very deep foundations, down to 70 feet of steel, H-pile, so they are very secure and resilient to overtopping.
Tell us a little bit more about this, because last time with Katrina the overtopping was a precursor to erosion, which caused them to break or breach. So have you avoided that, or is that still a risk here?
Well, the risk is any overtopping, of course, would exceed the design conditions. But what we've done on these levees, if the water comes over the floodwall, what we've put on the backside is scour protection.
So you have concrete on the backside. It's now a — not just an I-wall. It's a T-wall, so it's much more substantial with H-pile foundations.
So the erosion that occurred before, what — after the water came over, then it would sort of come under and that's what you mean by scour?
That's correct. Because once it goes over, it picks up about four times the speed once it begins to scour and erode on the backside. So we built the levees to be more resistant to scour.
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