Investigating Broken Levees
[Sorry, the video for this story has expired, but you can still read the transcript below. ]
BETTY ANN BOWSER: It’s one of the great American engineering mysteries and these two investigators are plodding through the muck in New Orleans looking for clues. Civil engineers Robert Kayen and Brian Collins are using computer mapping technology to help them understand why parts of the city’s 350 miles of levees failed, leaving thousands of homeless and hundreds of people dead.
INVESTIGATOR: This device is a laser imager it can hit upward of 6 million targets in a sweep of under ten minutes, and with that data we can make a 3-D model of the damaged area. And then we can look into the levee failure from any orientation on a computer.
BETTY ANN BOWSER: The two are part of a group brought in by the Army Corps of Engineers to conduct an unprecedented investigation sponsored by the National Science Foundation and the American Society of Civil Engineers. Paul Mlakar heads the team from the corps.
PAUL MLAKAR: What’s on the line and what we owe the American public is to rationally figure out exactly what happened here and the corps is determined to do that.
BETTY ANN BOWSER: But just one week into the probe into why the levees broke a more immediate problem emerged. One of the corps’s own independent investigators wrote a blistering letter to the corps, critical of the levee repair work in New Orleans.
Dr. Raymond Seed, a world famous civil engineer who heads a team of investigators for the University of California at Berkeley, wrote that the corps’ work at the 17th Street Canal breach “did not appear to have improved the situation, indeed,” he said, “it had likely made it more dangerous.”
Seed cited the row of big sand bags placed “like flower pots” on top of the damaged levee, saying they “did not block the likely points of water ingress.” Dr. Seed said open stone also placed on top would not be “effective in mitigating erosion of the underlying embankment.” And he wrote “dauntingly similar apparent shortcomings” exist at the other four breach sites which flooded massive sections of the city.
The American Society of Civil Engineers voiced similar concerns about the 17th Street Canal, saying, “stability in the repaired areas may be deteriorating.”
Responding to the criticism this week, the Army Corps said it has “already implemented the majority of the interim recommendations that pertain to the strengthening the breach sites.”
But Dr. Seed worries about a bigger problem — that years of budget cuts may have eroded the corps’ ability to protect public safety.
DR. RAYMOND SEED, Civil Engineer: If you’re dealing with highly complex systems and your manpower gets stretched thin enough, your ability to consistently and reliably catch all potential errors and flaws diminishes. Another way of saying that is, that if we under fund oversights and safety, we will eventually lose.
BETTY ANN BOWSER: Is that what happened in New Orleans?
DR. RAYMOND SEED: It would appear likely that is an issue that’s on the table.
BETTY ANN BOWSER: Donald Basham, the corps chief civil engineer, strongly disagrees.
DONALD BASHAM: The Army Corps isn’t going to let anything get built that isn’t safe and efficient to protect the American people. We may not build as much of it but that’s not a health and safety issue. What will get built though, I’m confident that we’ve got the expertise both within our organization and our construction companies to build infrastructure to protect the American people.
BETTY ANN BOWSER: Early on, the Army Corps said the levees failed not because of design faults, but because the powerful storm surge pushed water up over the concrete levee walls, undermining the structural foundation and causing them to give way. Lt. General Carl Strock is commander of the Army Corps of Engineers.
LT. GENERAL CARL STROCK: The area where the levee breaks occurred was at its final design configuration so that’s as good as it was going to get. And what does that mean? Actually we knew that it would protect from a Category 3 hurricane. In fact it has been through a number of Category 3 hurricanes. The intensity of this storm simply exceeded the design capacity of this levee.
BETTY ANN BOWSER: Investigator Paul Kemp of Louisiana State University’s Hurricane Center wasn’t so sure about that. While most of the levees were overtopped, his computer models told him that water did not go over the top of the levees at the 17th Street or at the London Canals, which would mean there was another reason for the levee breaks.
So Kemp and his researchers went out into the field. They measured how high the water went with flood lines that became visible as the water receded. What they found contradicted the corps early assessments.
PAUL KEMP: We’re close to the 17th Street canal. If this mark was in fact higher then the levees we would know that there was a very good chance that the levees, or that the seawalls that eventually failed had experienced overtopping, actually water had gone over the top of those levees. In fact, what we see is the mark is somewhat below the top of these levees.
BETTY ANN BOWSER: With Kemp’s finding the Army Corps and its independent investigators are now focusing on soil under the levees.
PAUL MLAKAR: The soil that was part of the levee is now 35 feet into someone’s backyard.
BETTY ANN BOWSER: Just as important as the design of concrete walls and sheet pilings that support them, the strength of the soil layers below the levee play a critical role. Investigator Dr. Peter Nicholson is a civil engineer from the University of Hawaii.
DR. PETER NICHOLSON: In this case it’s pretty clear that we had soil movement. So, that we know. How it failed, the mechanisms of that failure, what the loads were and ultimately what the details of that failure were, we don’t know, and that’s why we need to do further investigations of the soil, profiles and collect construction documents, to try and put the pieces of the puzzle together.
PAUL MLAKAR: It could be that the design was okay — that what was executed in the field was not the intent of the design, and for that reason, in addition to design documents we’re also capturing the construction records.
BETTY ANN BOWSER: Those records will be important because for years the corps has been outsourcing its construction projects to private contractors — something Dr. Seed says could compromise quality control.
DR. RAYMOND SEED: What you lose is consistency. And the problem with the levee system is if you have a number of segments which all have to make a single unit, you don’t get credit for 99 of those segments being at extra high quality if one of them is somehow weaker or less capable. And when you lose control and you do a lot of outside contracting with multiple firms you run the risk of losing consistency so the overall risk of the system is increased.
BETTY ANN BOWSER: But the Army Corps says the contracting is one of their strengths.
DONALD BASHAM: I would disagree that it’s caused inconsistency and more importantly the term lost control; I don’t believed we’ve lost control at all. For more than 20 years we have contracted out 100 percent of our construction work, and so we have had staff with appropriate oversight with those construction contractors.
BETTY ANN BOWSER: Although there has been criticism of both repairs in New Orleans and overall performance, Dr. Seed says in the end the blame should not fall entirely on the Army Corps of Engineers.
DR. RAYMOND SEED: This is very closely analogous to FEMA. FEMA has been attrited and under-funded. Their capabilities have been reduced, and now we’re all angry because they didn’t do a good job responding in the first week or so after Katrina. Corps of Engineers has been attrited and their capabilities have been reduced and I don’t think it’s appropriate for us to be making scapegoats out of organizations which against their own will, have had their support and their capabilities reduced. I think what we need to think about is perhaps refurbishing these organizations and getting them back up to the kind of strength which would perhaps be a better investment for the country
BETTY ANN BOWSER: The investigation into what went wrong in New Orleans comes at a time when the corps has said it will try to rebuild the levees back to what they were before Katrina — a system supposedly capable of withstanding a Category 3 hurricane. But the findings of the investigation could affect what the corps does in the future.
DONALD BASHAM: At the end of the day, whatever the failures were and whatever the cause of the failures, this chief engineer will be very open with American people. If we’ve done something wrong that needs to be corrected and we will stand behind that and make sure it gets corrected.
BETTY ANN BOWSER: Results of the investigation are expected in a few weeks. Meanwhile any plans to rebuild the levees above a Category 3 hurricane threat level must be approved by Congress.