You are here

universities

"Levee tests gnaw at termite expert"

From this:

A termite expert is questioning whether tiny, voracious Formosan termites played a role in the failure of levee walls in New Orleans during Hurricane Katrina.
Louisiana State University entomologist Gregg Henderson said there are clear signs that the destructive insects were present, and he wants the opportunity to dig into the levees beneath the walls to find out if termite nests contributed to their weakening.
Army Corps of Engineers officials, however, say no evidence has been found to indicate that termites undermined the integrity of the levees.
Henderson, a world-renowned expert on termites, found evidence of insects -- both Formosan termites and fire ants -- in the joints between wall panels on both the London Avenue and 17th Street canals. Fire ants, an enemy of termites, tend to invade the channels created by the wood-destroying insects...
At the London Avenue Canal, where several engineering teams believe the pressure of water in the canal undermined a weak layer of sand beneath levee walls and caused them to slide and fail, Henderson found insects in 73 percent of the joints, he said...
...Jerry Colletti, corps manager for completed public works, said engineers determined that the pinholes created by termites in the plastic joint spacers and in some cases in concrete were not dangerous...
..."The corps did an evaluation to determine how much water would come through those little pinholes," he said. "The decision was made not to take any action on the joints. We looked into sealing the joints, and it was going to be expensive and we didn't see a purpose to it; the pinholes didn't cause a structural integrity problem."
"We don't have anybody at the corps who's a termite expert," he said...

ACE discovered engineering mistakes in 1990, but did nothing

The Army Corps of Engineers did a design review of the New Orleans levees in 1990. Apparently the engineers on the project thought the soil under the 17th Street Canal was stronger than it was, and one of their offices discovered this at that time:

Corps documents show the mistake of overly optimistic levee strength was detected by its Vicksburg, Miss., office, which directed local engineers to make changes. But when the chief engineer in New Orleans replied that the results were based on "engineering judgment," his superiors dropped the issue.

And:

[Robert Bea, a University of California-Berkeley professor] said the discussion in the 16-year-old "design memo" points to the key decision that created fatal problems on the 17th Street Canal levee and could reveal a systemic problem that will show up during investigation into the London Avenue and Industrial Canal levees, which also breached during the Aug. 29 storm.

See also "Incredibly damning" evidence found about flood walls

ACE downplays lowered Katrina category

Army Corps of Engineers spokesman Susan Jackson responded to the news that Katrina was apparently weaker than originally reported as follows:

"In the Gulf, Katrina was a Category 5 storm, and the surge was still Category 5 when it hit the ground... It's the surge -- the pressure of water against those levee walls -- that's the most important factor, not the winds."

As previously discussed, there are questions over whether ACE's design of the levees and floodwalls was faulty or not.
And, the downgrading also affects LA's government:

"That storm was the biggest storm ever to enter the Gulf of Mexico," [Edmond J. Preau Jr., Louisiana's assistant secretary for public works] said in testimony before the Senate's Homeland Security and Governmental Affairs Committee. "I think it would be a real disservice to everyone if Katrina goes down in the history books as a '4' because the wind speed dropped at the last minute."

And:

To some local experts, the report was further evidence that human error was primarily to blame for New Orleans's drowning.
"This is a further indictment of the levee system," Ivor Van Heerden, an LSU professor and leader of a team of Louisiana investigators probing the cause of the levee breaches. "It indicates that most of the flooding of downtown New Orleans was a consequence of man's folly."
Other engineering experts agree: Considering Katrina's weakened state at the time it reached New Orleans, the failure of the city's 17th Street and London Avenue canal floodwalls can be explained only as a failure of design or construction, said Robert Bea, a civil engineering professor at the University of California at Berkeley.
"The water level in the canals wasn't that high when the floodwalls breached," said Bea, a member of an investigating team funded by the National Science Foundation. "We had a premature failure of the defense system."

"Dredging could have contributed to levee failure"

From this:

When the New Orleans Sewerage and Water Board developed a plan in 1981 to improve street drainage by dredging the 17th Street canal to increase capacity for Pump Station No.¤6, residents across the city applauded. Increasingly heavy rains were not only flooding streets, but pushing water into homes. Action was needed. It seemed like a no-brainer.
Today forensic engineers investigating the levee breach that flooded much of city during Hurricane Katrina aren't so sure. The search for the cause of the failure keeps returning to that dredging project as the probable starting point for a series of mistakes they believe ultimately led to the breach...
Before the project, the canal formed a roughly symmetrical "U" shape common to most canals. In the sections that would later fail during Hurricane Katrina, its average depth was about 12 feet below sea level and, at normal water levels, the Orleans side had about a 20-foot buffer of mud between the water and what was then a bare steel flood wall. That wall of sheet piling ran through the center of the levee to a depth 9.8 feet below sea level.
After the dredging, the bottom was 18.5 feet below sea level, and the canal-side levee had been shaved so narrow, water now touched the wall on the Orleans side. The "U" was now lop-sided and the water in the canal had shorter paths to the outside of the levee.
A review of records maintained by the two levee districts hasn't yet revealed why more extensive dredging was done on the Orleans side of the canal than on the Jefferson side.
"I've never seen a canal profile unbalanced like that, and I can't account for why it was done that way," said Bob Bea, a University of California-Berkeley professor and member of the Science Foundation team...

New Orleans flooding caused by Army Corps of Engineers' bad design?

"Team Louisiana", the state-sponsored "forensic levee investigation team" with "six LSU professors and three independent engineers" says the floodwall on the 17th street canal was bound to fail due to improper design that didn't take into account weak soils below the levee.
And, they say that bad design should have been obvious to those responsible: the Army Corps of Engineers, Eustis Engineering (a local company) and Modjeski and Masters (national company).

That miscalculation was so obvious and fundamental, investigators said, they "could not fathom" how the design team of engineers from the corps, could have missed what is being termed the costliest engineering mistake in American history.
..."It's simply beyond me," said Billy Prochaska, a consulting engineer in the forensic group known as . "This wasn't a complicated problem. This is something the corps, Eustis, and Modjeski and Masters do all the time. Yet everyone missed it -- everyone from the local offices all the way up to Washington."

Reaction here and here.
Previously: "Floodwalls in Swampy New Orleans 'Like Putting Bricks on Jell-O'"

Floodwall pilings seven feet shorter than Army Corps of Engineers said

From this:

Sheet piling supporting the failed floodwall on the 17th Street Canal extends just 10 feet below sea level, 7 feet shorter than the Corps of Engineers has maintained, a team of investigators said Wednesday [11/9], strengthening earlier findings that faulty design and construction played a role in the canal breaches that flooded much of New Orleans during Hurricane Katrina.
An LSU forensic engineering team, working in conjunction with the state attorney general's office, began examining the levee foundation with ground sonar Wednesday. The first reading was taken about 150 yards south of the break that allowed water from Lake Pontchartrain to inundate the city.
Independent engineers have questioned whether the pilings, even at the corps' stated depth, went down far enough to support the floodwalls and prevent storm surge from penetrating beneath the earthen levees and causing structural failure...

Looters left surprises behind in trendy stores; "liberals" explain

From this:

When she noticed the human waste on the floor of the trendy women's shoe boutique she manages, Lindsay Foret suspected looters had soiled the store out of spite.
"I was like, 'This is horrible. There's brand new bathrooms and they couldn't even go there?"' Foret said. "I went back to the bathrooms and they were perfectly fine."
As she spoke to fellow merchants along trendy Magazine Street, on the edge of the Garden District, Foret quickly learned she wasn't the only one who found such unseemly messes while trying to reopen a looted store.
Around the city, merchants returning after Hurricane Katrina who expected their worst problems to include storm damage or stolen merchandise have found numerous examples of vandalism, some of it vile, that apparently was meant to upset store owners.
"I can confirm some stores were vandalized -- and soiled, to some degree," city police Capt. Marlon Defillo said. He was not sure if it was widespread and said he could not comment on motives, but he suggested a lack of running water may have been a factor at times.
Sociologists say it may speak to the anger of a disenfranchised segment of the population and how -- at least during the chaos that ensued shortly after the storm -- they reveled in ruling certain places they may have previously perceived as snobby or out of reach.
"It is asserting a kind of power," Tulane sociology professor Martha K. Huggins said. "People who have their house broken into often say they feel violated, and defecating on the floor is the ultimate way to violate somebody...

Could gates, not floodwalls, have blocked storm surge?

From Many decisions led to failed levees:

It was a simple solution that could have prevented one of the worst disasters in the nation's history: metal gates at the mouths of New Orleans' canals that closed automatically to block hurricane storm surges on Lake Pontchartrain.
But the gates were never built. Local officials objected to the Army Corps of Engineers' plans in the 1980s, saying they would interfere with the city's antiquated network of pump stations that drain rainwater from the city.
The broken levees that flooded New Orleans after Hurricane Katrina have their roots in decades of decisions like the one to abandon the floodgates. The decisions reach all the way to Washington, where Congress in 1992 ordered the Army Corps to abandon the gates and instead build the network of flood walls that failed, according to Al Naomi, a corps senior project manager.
One of four teams investigating the levee failures told the Senate Homeland Security Committee on Wednesday that some preliminary indications of the levee failures are beginning to emerge, but it's still too early to say what caused the massive breaches.
A USA TODAY analysis of government documents and interviews with investigators, public officials and independent engineers shows that the underlying reasons for the flooding are compromises that undercut safety, miscalculations that underestimated risk and poor relations between the patchwork of agencies that oversee the miles of flood walls around New Orleans.
...Critical problems that underlie the failures behind the most costly flood in U.S. history:
• The 40-year-old analysis that served as the basis for how big to build the levees badly underestimated the potential for a large hurricane to hit the city.
The Army Corps of Engineers opted in 1965 to protect against what it believed would be the worst storm in 200 years. Congress agreed. Ivor Van Heerden, the leader of a Louisiana investigative team examining the levees, says that at least two larger hurricanes other than Katrina have hit New Orleans in the past 100 years.
By contrast, the Netherlands decided to protect itself against the worst storm possible in 10,000 years after more than 1,800 people died in a massive levee failure in 1953.
• New Orleans' levees - the result of the city's gradual growth rather than safety or efficiency - are riskier than those in neighboring communities.
Jefferson Parish, which adjoins New Orleans to the west, relies on a simpler system of levees at the lakefront to keep high water out. The levees are higher and stronger than the levees that failed on New Orleans' drainage canals.
As a result, Jefferson remained dry during Katrina.
• Safety is compromised by the patchwork of governmental agencies and private firms that share responsibility for designing, building and maintaining the levee system.
Investigators found numerous leaks where two sections of levees controlled by different authorities joined, says Peter Nicholson, a civil engineering professor from the University of Hawaii who heads a levee investigation by the American Society of Civil Engineers.
The problem is symbolic of a broader issue that has undercut safety over the years, say the investigators: Safety is too easily compromised because no single agency is in charge.
"You have multiple agencies, some of which aren't on speaking terms with each other," says Raymond Seed, another Berkeley professor who heads the investigative team from the National Science Foundation.
Just as the gates at the mouths of the canals were opposed by local levee and pumping agencies, environmental groups in the 1980s derailed plans to erect a structure to block storm surges from Lake Pontchartrain. Engineers now say that undercut safety.
• Investigators found signs that poor maintenance of levees had compromised safety.
Bea says he believes large trees allowed to grow near levees may have contributed to the failures. Investigators say they also found leaks caused by portions of levees that had sunk and not been repaired.
• The corps, which oversees levee design and construction, has steadily lost expertise in the face of budget cuts. That's "as shocking as what happened in New Orleans itself," Seed says.

Several tipsters: shortcuts used in building levees

Here's more on yesterday's Congressional testimony by Raymond Seed, who heads up a National Science Foundation team conducting a review of the levees and the floodwalls:

Several of the levees that flooded New Orleans may have been built with shoddy materials or by contractors who took shortcuts to save money, [Seed told Congress].
About a dozen people, including engineers and contractors, made the allegations of poor workmanship in recent weeks to investigators probing the levee failures, [Seed said].
The complaints focus on two canals where levees topped with flood walls were built in stages over the past 15 years. One of the claims is that contractors used steel sheets - which were driven into the levees to prevent water seepage - that were shorter than what was called for in designs. If true, that could have made the levees weak and prone to failure.
Other tipsters complained that inferior materials, such as porous soil, were used to construct the levees.
Robert Bea, another University of California, Berkeley professor working with Seed, said in an interview that he talked on the phone with two women who said they had specific information from their late husbands on construction shortcuts taken on the levees.
Seed said other investigators received similar complaints...

"Engineers Fear Levee Repairs Not Enough"

From this:

Repairs to New Orleans' levees may be insufficient to protect residents moving back to the devastated city if another hurricane comes before the tropical storm season ends this month, expert engineers said Wednesday.
Dozens of breaches continue to mar the city's levee system, including a large seep at the Industrial Canal last week, according to engineering experts who have examined the floodwalls...
At the Industrial Canal levee, which abuts New Orleans' obliterated Ninth Ward, repairs to breaches "were not adequate for a high-water incidence _ for instance, another hurricane storm surge with the storm season that isn't yet behind us, or even a very high tide," said Raymond B. Seed. Seed, a University of California at Berkeley engineering professor, participated in a National Science Foundation study investigating the levee failures.
The large seep at that levee, which occurred Oct. 24, "was not entirely unexpected," Seed told the panel.
However, he said, deeper walls "that will be far more stable than they were before" have been dug in at least some areas since the NSF first examined the levees.
"I don't think there is a long-term risk to the city of New Orleans," Seed said...

For Seed's full findings, see UC Berkeley: " Investigators release preliminary findings of levee failures at Senate hearing"

Pages

Subscribe to RSS - universities