[Vision2020] Army Corps Admits Design Flaws in New Orleans Levees

[Craine Kit]

Given the situation described in this report, wouldn't our tax  
dollars be better spent by buying the lands that will be drown again  
and returning them to what nature intended--a flood buffer--rather  
than building more very expensive (but useless) bulwarks?

Kit Craine

On Jun 2, 2006, at 9:35 AM, Art Deco wrote:

>
>
> http://www.latimes.com/news/nationworld/nation/la-na- 
> levee2jun02,0,3385244.story?track=tothtml
> From the Los Angeles Times
> Army Corps Admits Design Flaws in New Orleans Levees
> Its report says the defects were to blame for most of the flooding  
> and damage from Katrina.
> By Ralph Vartabedian
> Times Staff Writer
>
> June 2, 2006
>
> NEW ORLEANS — The Army Corps of Engineers acknowledged Thursday  
> that design defects in the levees protecting New Orleans caused the  
> majority of flooding during Hurricane Katrina and that the disaster  
> would almost certainly trigger reforms in how the federal  
> government protected the American public.
>
> The corps said its 40-year effort to construct a hurricane  
> protection system for southern Louisiana had resulted in a set of  
> piecemeal projects that "was a system in name only," a recognition  
> that a wide range of errors, weak links and incomplete construction  
> was at the heart of the massive damage that occurred Aug. 29.
>
> The corps released a 6,000-page report written in the couched  
> language of government engineers but which delivered a stunning set  
> of findings about errors made in the design of storm walls and  
> earthen levees that failed during Katrina.
>
> The report found that four major breaches of I-walls, a type of  
> concrete storm wall that sits on an earthen levee, caused 65% of  
> the flooding in the New Orleans area.
>
> Although the report's summary never uses the words "design defect,"  
> corps officials said they now accepted that their work had  
> shortcomings and errors that were responsible, in large part, for  
> the damage.
>
> "We do take accountability," Lt. Gen. Carl Strock, commander and  
> chief engineer of the corps, said at a news conference, where he  
> was joined by five Army generals, the federal coordinator for Gulf  
> Coast reconstruction and an assistant Army secretary.
>
> The corps, Strock said, "is deeply saddened and enormously  
> troubled" by the disaster.
>
> Strock said the remaining I-walls would eventually have to be  
> replaced because they proved ineffective during Katrina. The  
> primary breaches at the 17th Street, London Avenue and Industrial  
> canals occurred when storm waters were still several feet below the  
> tops of the walls, meaning they failed well below the maximum  
> forces they had been designed to withstand.
>
> The report also puts in the historical record a formal  
> acknowledgment of the scope of the disaster, which killed 1,293  
> people in the New Orleans area.
>
> "The flooding caused a breakdown in New Orleans' social structure,  
> a loss of cultural heritage and dramatically altered the physical,  
> economic, political, social and psychological character of the  
> area," it said. "These impacts are unprecedented in their social  
> consequence and unparalleled in the modern era of the United States."
>
> Although many of the technical findings had been released in  
> preliminary studies by the corps, the report details significant  
> new information:
>
> •  Southern Louisiana is sinking much faster than generally  
> recognized, and levees were at substantially lower elevations  
> relative to sea level than they were designed to be. In some cases,  
> levees were 2 1/2 feet below their designed elevations. Moreover,  
> as other federal agencies recognized the problem in recent years,  
> the corps decided not to reexamine the issue.
>
> •  The city's pumping system, the only way to remove water from  
> below sea level, was not designed to operate during a major storm.  
> Because most of the region's pumps were inundated after Katrina,  
> the corps was forced to use portable equipment that took 53 days to  
> pump out the city, allowing the flood waters to saturate and  
> destroy structures.
>
> •  Twenty-five percent of all the housing in the region was  
> destroyed. In New Orleans, the proportion is believed to be higher.  
> The destruction of homes accounted for 75% of the losses caused by  
> Katrina, estimated by the corps at more than $20 billion. Outside  
> estimates are much higher, exceeding $100 billion.
>
> •  A computer simulation showed that if the levees had not failed,  
> the city still would have flooded because 14 inches of rain fell  
> during a 24-hour period, and storm surges went over the levees. If  
> the levees had held, the flooding would have been about one-third  
> of what occurred.
>
> Strock said the repaired sections of levees were now the strongest  
> parts of the system. The repairs were supposed to be completed by  
> June 1, but they are about two months behind schedule. Among  
> ongoing projects is the installation of new pumps at the mouth of  
> the 17th Street Canal. The enormous undertaking required heavy  
> construction work on 169 miles of damaged or destroyed levees.
>
> The report is full of technical language, including descriptions of  
> design flaws as "overestimation of subsurface strength." Corps  
> officials said the reason for such language was not to reduce the  
> effect of the findings, but rather to set a "nonjudgmental tone."
>
> Although the breaches caused most of the flooding, a significant  
> part of the Katrina damage occurred because the storm was larger  
> than the system was designed to withstand.
>
> Although wind speeds had dropped sharply by the time the hurricane  
> hit New Orleans, its power over the Gulf of Mexico had created the  
> largest ocean surge to ever hit North America, the report said.
>
> The surges along the Gulf Coast reached 28 feet, and waves of 14  
> feet came on top of the surges, creating a 42-foot wall of water.  
> The ocean level was lifted by a drastic fall in the barometric  
> pressure, one of the sharpest drops ever recorded in the region,  
> Strock said.
>
> The same failure mechanism was to blame for all of the I-wall  
> breaches. As water rose against the walls, it caused them to tilt  
> away from the canals and open a small gap along the base of the  
> wall. Water rushed into the gap and cut the levee in half,  
> significantly reducing its strength.
>
> The water then penetrated deep into the foundation, causing  
> instability in the case of the 17th Street Canal levee and seepage  
> in the case of the London Avenue Canal levee. In both places, the  
> water penetrating the foundation weakened the system so much that  
> the earthen embankment shifted.
>
> The report said the corps failed to recognize the potential for  
> this failure. Outside experts, including a team of investigators  
> from UC Berkeley, said in a report last week that the corps had  
> ignored its own research that predicted such failures could occur.
>
> In addition, the corps' report said, its engineers had used  
> erroneous estimates of the soil strength under the levees. They  
> also used tests that were spaced too far apart and only took  
> averages of the soil strengths. The averages did not matter because  
> the levees failed in the weakest layers.
>
> The report does not attempt to explain why flawed decisions were  
> made. Reed Mosher, a senior geotechnical expert for the corps and  
> one of the principal investigators, said the biggest ingredient in  
> the errors was the technology in use at the time the walls were  
> designed.
>
> "We wouldn't make the same mistakes today," he said.
>
> The UC Berkeley engineers said the technology and know-how existed  
> to build stronger levees, but the corps had lost some of its  
> expertise starting in the 1980s as it shifted emphasis to managing  
> projects and let private engineers do the design.
>
> Strock said he "would not make apologies" for focusing on project  
> management and disputed the assertion that the corps had lost its  
> technical competence. A second investigation led by the University  
> of Maryland is scheduled to report next month on the institutional  
> and cultural factors within the corps that may have led to the errors.
>
> The corps' investigation, known officially as the Interagency  
> Performance Evaluation Task Force, was conducted by 150 experts and  
> led by University of Maryland engineer Lewis E. Link. The report  
> unveiled Thursday is a draft; a final version is due in September.
>
> The findings will trigger significant changes in how the corps and  
> other government agencies protect the public from storms and  
> floods, Strock said.
>
> The corps is responsible for 12,000 miles of levees across the U.S.  
> It will start treating the levees with the same oversight as it  
> does with dams, which have historically received a higher priority  
> in terms of public safety.
>
> Maj. Gen. Donald Riley, director of civil works for the corps, said  
> reforms were also coming in how flood protection systems were  
> designed and built.
>
> In the future, he said, levees and other flood protection projects  
> will have greater resiliency, so that even if storm waters  
> overwhelm them, they will reduce the effects of floods and allow  
> for a faster recovery.
>
> The corps will abandon its use of an antiquated method of  
> estimating storm forces, known as the standard project hurricane,  
> Riley said. It was that model that led the public to incorrectly  
> believe that the New Orleans levees could withstand a hurricane as  
> powerful as Katrina.
>
> In deciding whether to build levees, the corps has long used cost  
> benefit analysis that considered the potential loss of property,  
> not human life or the social value of a city. Now, he said, diverse  
> factors will be considered when evaluating whether to build levees.
>
> Riley said the corps also would be adopting a different system to  
> evaluate the risks and consequences of its systems. Since Katrina,  
> outside experts said the corps erred in risk analysis of its levees  
> and should have built much larger margins of safety. Riley said the  
> new system would use modern risk analysis and would become a  
> national standard.
>
> Strock acknowledged that the corps must prove to the public that it  
> could provide a higher level of performance.
>
> "For those who doubt us, words alone will not change minds," he said.
>
> But the agency has emerged from the disaster as a stronger  
> organization, he said.
>
> "We are not wringing our hands; we are going to work."
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