...Levees and storm walls may be as much as 2 feet lower than they were designed to be, both because elevation data were outdated when the levees were built and because the land has continued to sink, [some experts] say.
...Experts also are studying the Army Corps of Engineers' 1990s project that topped existing earthen levees with concrete walls to strengthen New Orleans' hurricane defenses. The approach was economical but may have left the walls weaker than intended. Three concrete walls failed after Katrina hit Aug. 29, to catastrophic result.
Engineering experts [including Ivor L. van Heerden, deputy director of the Louisiana State University Hurricane Center] say the designs failed to use the most modern technology, had almost no redundancy to compensate for minor problems during a storm, and were further undermined by weak clay soils in the New Orleans area...
...In other areas, including eastern New Orleans, overflow destroyed many miles of levees.
...[Louisiana State University engineering professor Roy K. Dokka] had warned in the last two years of an approaching disaster. "The most recent data shows that all of the previous subsidence work was faulty," he said.
On average, coastal Louisiana has been sinking half an inch annually, he said. But New Orleans East, which saw devastating flooding when levees overflowed, is sinking faster. Many levees are at least 6 inches lower than they were designed to be, and those in New Orleans East and badly damaged Plaquemines Parish are perhaps 2 feet lower.
...Geological and human forces are causing land elevations to drop, said Virginia R. Burkett of the U.S. Geological Survey's National Wetlands Research Center in Louisiana.
Over thousands of years, coastal subsidence was offset by Mississippi River sediment deposits, Burkett said. But dams and other water projects on tributaries have halved river sediment since 1950, and levees on the main river channel now carry the remaining sediment deep into the gulf rather than spreading it along the coast.
Offshore oil and gas extraction have accelerated subsidence in some areas, Burkett said. And swamp drainage, particularly under New Orleans, has caused organic soil matter to decay and compact, adding even more to the subsidence.
As levees have sunk, melting glaciers have lifted ocean levels globally, she added.
The problem is expected to worsen in the coming century...
...In 2001, the National Geodetic Survey warned Congress that elevation surveys for Louisiana were "obsolete, inaccurate and unable to ensure safety."
...Two years ago, the agency began recalibrating Louisiana elevation data using the Global Positioning System, Deputy Director David Zilkoski said. But Katrina struck before the project could make a difference.
In the year before Katrina, Zilkoski said, he went from town to town to warn local officials that elevation data in the region were inaccurate, including those that showed evacuation routes.
...Meanwhile, LSU's Van Heerden expressed concern that the 1990s work to place concrete walls atop levees might have contained fundamental design flaws.
The new walls were tied into existing steel sheeting inside the earthen levees. In some cases, the tops of the steel and the footings of the new concrete walls overlapped by just 2 feet. Steel reinforcement bars were welded or looped into the sheeting to tie the structures together, he said.
Van Heerden said he believed the walls on the 17th Street and London Avenue canals failed because they could not resist the water pressure, not because of overflow or foundational erosion.
He said the storm walls snapped where the steel sheeting met the concrete walls. He said it was generally bad practice to use old sheeting as a foundation.
Katrina would also have weakened the levees' clay soils, a further potential cause of failure.
Geotechnical engineering professor Dobroslav Znidarcic of the University of Colorado at Boulder said he was surprised concrete walls were used for the levees.
Few retaining walls are made of reinforced concrete anymore, he said. Instead, "mechanical stabilized earth" can provide greater strength and resistance to total failure. The system, developed in the late 1980s, sandwiches fabric grids between layers of soil.
"I am concerned their design is prone to catastrophic failure if anything goes wrong," he said. "It does not have a sufficient level of redundancy."
Lisa Myers of NBC reports in "New Orleans levee reported weak in 1990s":
NBC News has obtained what may be a key clue, hidden in long forgotten legal documents. They reveal that when the floodwall on the 17th Street Canal was built a decade ago, there were major construction problems - problems brought to the attention of the U.S. Army Corps of Engineers.
A 1998 ruling, by an administrative judge for the Corps' Board of Contract Appeals, shows that the contractor, Pittman Construction, told the Corps that the soil and the foundation for the walls were "not of sufficient strength, rigidity and stability" to build on.
"That's incredibly damning evidence," says van Heerden, "I mean, really, incredibly damning."
Pittman won the contract in 1993. There already was an earthen levee made of soil. Embedded in that was a thin metal wall called sheet piling. The contractor was hired to pour concrete on top of all that to form the flood wall.
But the 1998 documents - filed as part of a legal dispute over costs - indicate the contractor complained about "weakness" of the soil and "the lack of structural integrity of the existing sheet pile around which the concrete was poured." The ruling also referenced the "flimsiness" of the sheet piling.
NBC showed the findings to engineering experts.
"That type of issue about the strength of the soils, of course, bears directly on the performance of a floodwall," says LSU engineering professor Joe Suhayda.
"I think it is very significant," adds Robert G. Bea, a former Corps engineer and professor at the University of California, Berkeley, who is part of a National Science Foundation inquiry into the failure of flood controls. "It begins to explain some things that I couldn't explain based on the information that I've had."
The construction company said as a result of these problems the walls were shifting and "out of tolerance," meaning they did not meet some design specifications. Nevertheless, the Army Corps of Engineers accepted the work.
"It seems to me that the authorities really should have questioned whether these walls were safe," says van Heerden.
The judge, in her ruling, blamed the contractor for the construction errors and turned down Pittman's request for more funds.
Pittman is now out of business. The ACOE says it will investigate, and it's preserving documents...
They provide this 6.4Meg PDF file with the ruling.
I'll leave it to someone else to figure out if anything illegal was done in the following, but it shure sounds suspicious:
Less than a month before Hurricane Katrina wrecked the Orleans Levee Board's finances and left the levees it maintains in shambles, board President Jim Huey requested and got nearly $100,000 in back pay that the agency's hired legal advisers - one of whom is a relative of his wife - determined he was entitled to receive.
The payment for about $96,000, which was made without approval from the board or its staff attorney, came on the advice of Gerard Metzger and George Carmouche, two contract lawyers with close ties to Huey, who was originally appointed by former Gov. Edwin Edwards in 1992 and reappointed by Govs. Mike Foster and Kathleen Blanco. Carmouche, of Baton Rouge, is a first cousin of Huey's wife, Becky Metzger of Metairie, and has been a close friend of Huey's since the two attended high school together at Holy Cross.
After cursory research, board officials indicated several months ago that Huey, who has no formal administrative duties, was not eligible for any compensation beyond the $75 per diem that board members can receive for each day they work on agency business.
State lawmakers also rejected the extra pay for Huey. In the waning hours of the Legislature's 2005 session, state Sen. Francis Heitmeier, a Huey ally, tried unsuccessfully to make Huey eligible for a $60,000 annual salary by inserting the pay provision into an unrelated piece of legislation...
UPDATE: Huey has resigned, and "AG Foti: fmr. Levee Board president Jim Huey broke law".
This post reprints an email from Allan McIsaac, who is apparently an engineer who worked on NO's levee system for the feds:
I tell you truly that in my 40-year career as an engineer, the local authorities in our New Orleans levee project take the prize in the area of callous disregard and their bungling remains notorious to this day. Truly, it was scandalous. Consequently, I find it hard to cast a major portion of blame for this disaster on any other entity than the local representatives of those unfortunate people in New Orleans. The truth is, at least the last three mayors of New Orleans are grossly negligent and in dereliction of duty in regards to repeatedly skimming federal funds allocated for their levee fortification.
There are several pictures of a barge that ran into a levee here. Note that those are on the Mississippi River side of things, and apparently no flooding was caused by those barges. Here's an aerial shot.
However, a commentor at a previous post of his site had this to say:
I've been speaking with some evacuees that have been transplanted in my community and they say that there is a RUMOUR, and I do mean RUMOUR, that Beau Brothers Construction had some barges near the levees that were not tied properly; and as a result they banged against the walls and weakened them during the storm. I don't know anything more about it than what I just posted.
Ivor van Heerden and others from LSU's Hurricane Center now say that the flooding of New Orleans was caused by either faulty design or fault construction of the floodwalls, rather than overtopping or other explanations: "Experts Say Faulty Levees Caused Much of Flooding". (Note that the WaPo's headline is confused: they aren't talking about the levees).
LSU has constructed computer modeling showing that the surges did not overtop the floodwalls:
...[Van Heerden] said the real scandal of Katrina is the "catastrophic structural failure" of barriers that should have handled the hurricane with relative ease.
"We are absolutely convinced that those floodwalls were never overtopped," said van Heerden, who also runs LSU's Center for the Study of Public Health Impacts of Hurricanes.
In an interview Tuesday, [Army Corps of Engineers] spokesman Paul Johnston said the agency still believes that storm surges overtopped the concrete floodwalls near the lake, then undermined the earthen levees on which they were perched, setting the stage for the breaches that emptied the lake into the city.
Johnston said the Corps intends to launch an investigation to make sure it is correct about that scenario. But he emphasized that Katrina was a Category 4 hurricane when it smashed into the Gulf Coast, whereas Congress authorized the Corps to protect New Orleans against a storm only up to Category 3. "The event exceeded the design," Johnston said.
On a tour Tuesday, researchers showed numerous indications that Katrina's surge was not as tall as the lakefront's protections. They showed a "debris line" that indicates the top height of Katrina's waves was at least four feet below the crest of Lake Pontchartrain's levees. They also pointed out how the breached floodwalls near the lake showed no signs of overtopping -- no splattering of mud, no drip lines and no erosion at their bases. They contended that the pattern of destruction behind the breaches was consistent with a localized "pressure burst," rather than widespread overtopping.
The center has also completed a computerized "hindcast" of Katrina, which has confirmed the evidence before their eyes. Their model indicates that most of the surge around the lake and its nearby canals was less than 11 feet above sea level, and that none of it should have been greater than 13 feet. The Army Corps's flood-protection system for New Orleans was designed to handle surges of more than 14 feet above sea level.
"This should not have been a big deal for these floodwalls," said oceanographer G. Paul Kemp, a hurricane expert who runs LSU's Natural Systems Modeling Laboratory. "It should have been a modest challenge. There's no way this should have exceeded the capacity."
This is from Aug 31, and discusses the funding for New Orleans' levees. I believe some of it has been contradicted by later reports, such as the news of what the levee board spends its money on.
The ''more funding for levees'' argument perpetuates a common misperception. The long-standing earthen levees surrounding the city did not fail. It was the floodwalls around the drainage canals that protrude into New Orleans that were overwhelmed. One breach seems to have been caused by a barge breaking loose from its moorings and battering down one of the walls. Will Nancy Pelosi now accuse Bush of underfunding barge moorings?
...In fact, the section of 17th Street canal where a major breach occurred had just been upgraded, and The New York Times writes ''received more attention and shoring up than many other spots in the region.'' Even if Bush had larded more money on New Orleans - according to a broad-brush comparison in The Washington Post, he spent more in his first five years in office than Bill Clinton did in his last five - it wouldn't have stopped such a breach...
...The Washington Post reports that only 3 percent of the port's cargo comes through the [Mississippi River Gulf Outlet], at a price to taxpayers of an estimated $12,000 per vessel. Still, the U.S. Army Corps of Engineers spent $13 million dredging the canal last year. Even though there were warnings about the dangers of MRGO, even though it was commercially marginal, the Corps wanted to spend up to $38 million on keeping it going...
The article "Is the Orleans Levee Board doing its job?" would be funny if it weren't so disturbing.
- $2.4 million on the Mardi Gras Fountain...
- $15 million for overpasses to Bally's riverboat casino...
- $45,000 for "private investigators to dig up dirt on radio host and board critic Robert Namer"...
- $45,000 on the settlement after Namer sued...
Critics charge, for years, the board has paid more attention to marinas, gambling and business than to maintaining the levees. As an example: of 11 construction projects now on the board's Web site, only two are related to flood control.
"I assure you," says Levee Board President Jim Huey, "that you will find that all of our money was appropriately expended."
Huey says money for the levees comes from a different account than money for business activities and that part of the board's job is providing recreational opportunities.
And despite the catastrophic flooding, Huey says, "As far as the overall flood protection system, it's intact, it's there today, it worked. In 239 miles of levees, 152 floodgates, and canals throughout this entire city, there was only two areas."
But those two critical areas were major canals and their collapse contributed to hundreds of deaths and widespread destruction.
Whether the Board could have done anything about the floodwalls that failed will probably be determined later.
UPDATE: Huey has resigned, and "AG Foti: fmr. Levee Board president Jim Huey broke law".
Piecing together the unconfirmed timeline presented in "Key military help for victims of Hurricane Katrina was delayed" we get:
- Aug 29: landfall; "levee breaches" occur
Aug 29 3:22:00 PM - Navy says USS Bataan is standing by.
- Aug 30: Michael Chertoff goes to Atlanta for a "previously scheduled briefing on avian flu"
- Aug 30: "[Chertoff] aides also concede that Washington officials were unable to confirm that the levees in New Orleans had failed until midday on Aug. 30. The breaches were first discovered in Louisiana some 32 hours earlier."
- Aug 31: CNN mentions Bataan in passing.
- Aug 31: "President Bush went on national television to announce a massive federal rescue and relief effort"
- But orders to move didn't reach key active military units for another three days. (Sep. 2?)
Once they received them, it took just eight hours for 3,600 troops from the 82nd Airborne Division at Fort Bragg, N.C., to be on the ground in Louisiana and Mississippi with vital search-and-rescue helicopters. Another 2,500 soon followed from the 1st Cavalry Division at Fort Hood, Texas.
Then, from "Military May Play Bigger Relief Role":
[Sep. 3:] The active-duty elements that Bush did send to Louisiana and Mississippi included some Army and Marine Corps helicopters and their crews, plus Navy ships. The main federal ground forces, led by troops of the 82nd Airborne Division from Fort Bragg, N.C., arrived late Saturday, five days after Katrina struck.
And, from Sep. 4 comes "Navy ship nearby underused" about the Bataan.