From the LA Times, we have a story that I doubt will get much play outside of that particular newspaper because the usual suspects continue to want to blame all the New Orleans Katrina woes on the President. The newspaper reports:
Soil Failure, Not Overflow, Cited in Levee Breaches
Separate investigative teams reach conclusions that are at odds with the original explanation.
The levee breaches along two major canals that flooded New Orleans after Hurricane Katrina resulted from massive soil failures under concrete storm walls, not from hurricane surges that sent water over the tops of the walls as Army officials initially said, according to teams of investigators who have examined evidence in the last week.
The findings appear to chip away at the simple story that the storm surge was much larger and higher than the walls were designed to handle, though investigators caution that it is too early to blame design or construction.
“No question there was soil failures,” said Peter G. Nicholson, a University of Hawaii engineering professor who is leading an investigation for the American Society of Civil Engineers. “But we can’t speculate whether it was a construction, material or design flaw.”
If soil problems are widespread in New Orleans’ 350 miles of protective levees, then upgrading the system to protect against hurricanes more powerful than Katrina could require a major investment.
Immediately after the storm, the Army Corps of Engineers thought that a surge from Lake Pontchartrain had moved up drainage canals in the city and overflowed concrete storm walls, eroding foundations and leading to the breaches.
Investigators have found no evidence of such overflow and foundational scouring at the breaches in the London Avenue and 17th Street canals, two main failures behind the central New Orleans flooding. In fact, in one case, water marks are a full 2 1/2 feet below the tops of the walls.
Instead, investigators have found strong evidence that the soil structure was too weak for the pressure of the water, wind and waves.
Soil failure is like pushing on a chocolate cake that is sitting on a plate: At first the cake sticks to the plate, but if you push hard enough the gloppy structure eventually moves, said Raymond B. Seed, an engineering professor at UC Berkeley who is leading a separate National Science Foundation investigation of the levee breaches.
So far, Seed thinks the failure of the soil structure initiated the breaches at London Avenue and 17th Street. The levees were constructed on “particularly unfavorable” foundations of organic peat, which is both compressible and weak, he said.
Captain Ed nails it:
This shows the foolishness of making snap judgments about fault in the immediate aftermath of a catastrophe. The experts, both locally and at FEMA, had concluded that based on water levels at the levees the city would be safe from a systemic failure and widespread flooding. That resulted in the cheery prognoses offered by Michael Brown, Ray Nagin, and others on the Monday of the levee failures. No one knew that the levees had base design deficiencies, nor could they tell until after the levees failed. That does not let Louisiana or New Orleans off the hook for not properly evacuating the city in accordance to its plans, but it at least shows why the concern dropped after Katrina passed through the area.
Yep. While Ed’s analysis is spot on, I also have a big complaint with the media, who engaged in premature conclusion-based reporting – the conclusion being that the reason these levees were breached were because the funding for them had been cut by the Bush administration (even though the funding issues went back decades) – just days after the levees broke, prior to any formal investigations into the matter. This is what happens when you’ve got a story-hungry media hell bent on being “the first” to report “breaking news” – not to mention that I’m sure there were more than a few reporters who wanted to be able to pin the levee breaks on the (understandably) media-unfriendly Bush administration.
(Cross-posted at Blogs For Bush)