Posted on 05/22/2008 10:21:51 AM PDT by janetjanet998
NEW ORLEANS - Despite more than $22 million in repairs, a levee that broke with catastrophic effect during Hurricane Katrina is leaking again because of the mushy ground on which New Orleans was built, raising serious questions about the reliability of the city's flood defenses
Outside engineering experts who have studied the project told The Associated Press that the type of seepage spotted at the 17th Street Canal in the Lakeview neighborhood afflicts other New Orleans levees, too, and could cause some of them to collapse during a storm.
The Army Corps of Engineers has spent about $4 billion so far of the $14 billion set aside by Congress to repair and upgrade the metropolitan area's hundreds of miles of levees by 2011. Some outside experts said the leak could mean that billions more will be needed and that some of the work already completed may need to be redone.
"It is all based on a 30-year-old defunct model of thinking, and it means that when they wake up to this one — really — our cost is going to increase significantly," said Bob Bea, a civil engineer at the University of California at Berkeley.
The Army Corps of Engineers disputed the experts' dire assessment. The agency said it is taking the risk of seepage into account and rebuilding the levees with an adequate margin of safety.
"It's always a potential, so it is a design component for every feature," said Walter Baumy, the chief corps engineer in New Orleans.
The 17th Street Canal floodwall collapsed on the day Katrina surged over New Orleans in August 2005, and the failure severely damaged Lakeview. It was one of the biggest of about 50 levee breaches that contributed to the deaths of about 1,300 people.
Fixing the 17th Street Canal has been one of the most expensive and laborious repair jobs since the storm and has served as something of a test case for scientists and engineers, who plan to apply the lessons learned there to the city's other levees.
Among other things, they repaired the wall by driving interlocking sheets of steel 60 feet into the ground, compared with about 17 feet before the storm. The sheet metal is supposed to prevent canal water from seeping under the levee through the wet, toothpaste-like soil that lies beneath the city, which was built on reclaimed swamp and filled-in marsh.
Over the past few months, however, the corps found evidence that canal water is seeping through the joints in the sheet metal and then rising to the surface on the other side of the levee, forming puddles and other wet spots.
Engineers said the boggy ground is a more serious problem than the corps realizes. Bea said there is a roughly 40 percent chance of the 17th Street Canal levee collapsing if water rises higher than 6 feet above sea level. During Katrina, the water reached 7 feet in the canal.
John Schmertmann, a retired University of Florida professor and a consultant on foundations, agreed with Bea that the corps "may still be embedding some of these not-properly-considered factors, so the new walls may not do what the corps expects."
Reducing such seepage might require the driving of sheet metal far deeper into the ground than is done now, or some other solution, said Bea, who was part of a team of experts sent by the National Science Foundation to do an independent study of the levee failures during Katrina.
Donald Jolissaint, chief of the corps' technical support branch in New Orleans, denied the problem at the 17th Street Canal is serious.
"I personally do not at all believe that this little wet spot is anything that is going to cause a breach or a failure of any kind," he said. A newly installed floodgate could be used to cut off the flow of water into the canal and reduce pressure on the levee, he said.
Nevertheless, the corps is concerned enough that for weeks, workers have been analyzing the wet spots and digging a 160-foot-long, 10-foot-deep trench to zero in on the source. "We're doing everything we can to chase this down," Jolissaint said.
The corps is also spending about $100 million by taking more than 2,000 soil borings to find out what is under the ground and determine the best design.
Timothy Kusky, a geologist with Saint Louis University and an expert on the Mississippi River, said engineering a safe levee system in New Orleans will be very difficult because of the soil.
"You've got old riverbeds and floodplain deposits all interlayered and distributed laterally in a very complex way, and then you build a levee across them," Kusky said.
As a result, a levee sinks at different rates, and the sinking creates "little cracks in them that promote seepage, and also the old river channels and floodplain deposits have different potentials for underseepage," he said.
He said the corps understands a lot of the problems, but it takes a huge amount of data to map every weakness, and the agency does not have the manpower to see that every contractor is doing the job right.
Seepage was reported at the 17th Street Canal before Katrina. The corps denies that caused the collapse. Instead, the corps contends the floodwall flexed and finally cracked under the force of water piled against it by the storm.
Once again..living below sea level with water on three sides....not good.
There were some reports after Katrina indicating that during the Clinton administration, funding to reinforce the levees was given to Louisiana, but somehow the money didn’t get spent as intended.
Then again, does any of this matter, if natural forces will sooner or later overwhelm the site where New Orleans is.
Didn’t some Republican congressman get raked over the coals for suggesting that New Orleans shouldn’t get redeveloped at the current site? of course since he was Republican, it was racist and a slight to the poor of New Orleans as well to say that.
Mayor Nagin wants a chocolate city in New Orleans again. You figure many of the former residents will never return, and again calls into question whether it should be rebuilt. And if not rebuilt, calls into question whether it’s a good expenditure to rebuild the levees.
I saw the title Leaky and I thought it was going to be an article about democrat senator Patrick “Leaky” Leahy.
We sure are going to great lengths to preserve a place where we go to drink and misbehave.
So, how long before this is mentioned in an Obama speech?
Carl Rove screwed up this time. It wasn’t supposed to leak until the next hurricane hit New Orleans. No wonder he resigned.
Blow all the levies, and build on whatever remains above water..
If ever a city wasn’t meant to be where it is.....it is New Orleans...
The “risks” presented by Global Warming, makes New Orleans even less likely to survive....
We’re literally pouring money into a hole in the Gulf....
I’m reminded of the passage from David Brin’s “Earth”: Can you hear the Atchafalaya calling, Mississippi?
$100,000,000 / 2,000 = $50,000 for each soil boring. Sound like some contractor is making a killing off the project. Taking a soil boring is not much different than drilling a water well, except you don't have to drill as deep for a boring.
Sounds like a great use of tax dollars in the chocolate city.
Then take it someplace else. Some of “we” live there and don’t care for drunks stumbling out of lapdance joints to vomit in our streets.
The Army Corps of Engineers has spent about $4 billion so far of the $14 billion set aside by Congress...of your tax money to piss away!
Mother Nature says...forget about it! Just move ‘em out and screw the levees!
And there goes the other shoe dropping. Anyone surprised? Anyone?
Just blow the river leevee and things will take care of themselves.
Planned Parenthood agrees. PP did not get them before they were born, so move 'em all back into the city and drown them when the levees breach again. See Margaret Sanger's "Negro Project".
Whatever the case... we Texans are all full up with Katrina evacuees. Time for some “progressive” west or east coast liberal city to take their share of the liberal plantation that they created.
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