Posted August 31, 2008 10:39 AM
by Frank James
I just watched Homeland Security Sec. Michael Chertoff's brief press conference at Andrews Air Force base just before he got on a plane to head to the Gulf Coast region to check in on preparations for Hurricane Gustav.
The secretary, a very nice man, said the levees are stronger than they were before Hurricane Katrina. Chertoff should doublecheck that information.
The reporting I've read indicates that the levees are not generally and absolutely stronger. True, some levees have been strengthened and rebuilt after they failed.
But there've been questions about the rebuilding efforts that reconstructed levees that failed after Katrina.
There's also been seepage under a few of the levees that has confounded the Army Corps of Engineers.
Some of the levees that held up under Katrina are among those that experts are most worried about.
Here's a story from New Orleans's Times-Picayune newspaper from April 17, 2008.
Despite withstanding Hurricane Katrina and being poised to become the area's first levee to reach the vaunted 100-year storm elevation, the East Jefferson lakefront levee might not be adequate and may need to be totally rebuilt or substantially enlarged.
Stunning new data spit out by a complex geotechnical computer model has concluded that lake levees in East Jefferson and St. Charles Parish could be at risk for catastrophic failure.
Though Army Corps of Engineers officials said some experts doubt the accuracy of the new analysis, the agency intends to identify and implement solutions -- which could range from entirely rebuilding the levees to constructing a huge rock jetty in front of them.
"Our new method of analysis has given us (data) that we don't intend to ignore," said Lt. Col. Murray Starkel, deputy commander of the corps' New Orleans District.
Because the corps is under the gun to provide an improved hurricane protection system by 2011, officials said they can't wait for the results of additional studies that might ultimately debunk this new finding of the "Spencer's method" analysis.
"There will come a point at which we go forward with (contracts), even if they produce an overly conservative design," said geotechnical engineer John Grieshaber, technical support chief for the corps' Hurricane Protection Office.
"We will award contracts to meet that 2011 date, and if we find out later that we can do with a less conservative design, we can modify a contract in the field," he said.
Design standards updated
The computer-generated data, which blindsided even those engineers overseeing planned improvements to the region's hurricane protection system, are the result of applying more conservative design standards adopted since Katrina.
Key to that corps effort to ratchet up reliability, complex computer software was specially adapted over the past year that enabled the Spencer's analysis to identify any type of failure that could possibly occur in tricky south Louisiana soils.
As recently as January, engineers overseeing planned improvements to the East Jefferson lakefront predicted that it would be the first to attain the new elevations needed to help provide a stepped-up 100-year level of storm surge protection by 2011.
But the very next month, the Spencer's software began unspooling the news that it had identified a failure potential not detected by previous computer analyses in the Lake Pontchartrain levees of East Jefferson and St. Charles Parish.
"No, we absolutely did not expect this result," Rich Varuso, geotechnical chief for the district's engineering division, said of the geometry-based calculations that resulted.
Continued>>>
http://www.swamppolitics.com/news/politics/blog/2008/08/new_orleans_levees_remain_worr.html
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