Thursday, December 08, 2005

Human Errors

There's no need to bomb the levee system to cause the flooding when there were plenty of structural and design deficiencies that were more than sufficient to cause the flooding as the flawed levees gave way in the storm.
The levee flaws also raise troubling questions about the integrity of flood defenses elsewhere.

"Everybody who has a levee out the back door now has to look out and wonder, is this going to fail? Was it designed right?" said Steve Ellis, vice president of Taxpayers for Common Sense, a Washington fiscal watchdog group critical of the corps' priorities.

Corps spokesman David Hewitt said the agency has several experts and engineers from outside agencies, private firms and academia to aid its investigation. "We are determined to find out exactly what happened both in the technical engineering and the planning and execution process so that we can prevent another occurrence," Hewitt said. "We are engaging the best minds and professional expertise in this important effort."

Engineers say most structures that fail do so not because they're hit by overwhelming forces, but because of flaws that creep in unnoticed during design, construction and upkeep. A paper published this month by Robert Bea, an engineering professor at the University of California at Berkeley who is studying the levee failures, concluded that 80 percent of 600 structural engineering failures he studied in the past 17 years were caused by "human, organizational and knowledge uncertainties."

Bea said everything he has seen about the New Orleans levee system so far tells him it belongs in that category.

Not as good as advertised

The levee system's design dates to the 1950s, when understanding of hurricane risks and flood dynamics was primitive compared to today. The system was never built to take a hit from the most powerful hurricanes, storms in Categories 4 or 5 on the Saffir-Simpson scale. The levees were designed by congressional mandate to fend off floodwater heights -- up to about 11 or 13 feet, depending on location -- that Category 1 or 2, and some Category 3 storms would kick up.

But the investigations show that the levees did not live up even to that billing. When Katrina's storm surge rolled in from the Gulf of Mexico before dawn Aug. 29, the huge dome of water followed a path up the Mississippi River and then along the Mississippi River-Gulf Outlet into Lake Borgne.

In a matter of hours, the sheet of water -- reaching 25 feet high at some locations -- moved relentlessly north and west, pouring over the tops of and eroding large stretches of levees surrounding Chalmette, clearly exceeding their design capacity.

When the surge reached New Orleans' southern edge along the Gulf Intracoastal Waterway, it caused as much as five miles of the 17.5-foot tall levee there to disappear, creating a back door for water into eastern New Orleans.
In North Jersey, the Army Corps of Engineers has been dealing with flooding on the Ramapo River for years, and their most recent attempts at flood control have actually made things worse - more severe flooding upstream from a dam that is being reengineered. Elsewhere in the country, levees and flood control projects should be reevaluated and inspected far more rigorously than they have been to date in order to uncover and repair problems that may not have been caught to date.

And among the items that must be reevaluated is the safety factor for the levee systems protecting major urbran areas and densely populated areas downstream or in the flood zone. It appears that the current safety factor is insufficient to deal with varying subsoil conditions. Overestimating the strength of the subsoils may have contributed to the levee failures.

Meanwhile, Gov. Barbour of MS is calling on Congress to pass a spending plan that would include homeowner relief so that homeowners who lost their homes due to the storm surge and flooding can gain relief from mortgage payments on homes that no longer exist or are damaged beyond repair.
Barbour has requested a total relief package of about $34 billion, spread over the next several years, which includes about $17 billion from the more than $62 billion already allocated for Katrina by Congress. Barbour said the key item in the state's request is about $4 billion for a homeowner bailout - money to help about 35,000 homeowners who didn't have separate flood insurance, but lost their homes to Katrina's water. Without this, Barbour said, thousands of people are likely to leave the storm-ravaged area, causing a collapse in the rebuilding and recovery efforts.

The House on Wednesday passed hurricane tax-relief legislation 415-4 for Louisiana, Mississippi and Alabama. The legislation differs from a Senate tax relief for the Gulf region by not offering tax incentives to country clubs, casinos, hot-tub facilities, liquor stores, massage parlors, private or commercial golf courses, racetracks and suntan facilities.

Gulf state lawmakers complained legitimate employers should all benefit from the tax incentives. Rep. Shelley Berkley, D-Nev., whose district includes Las Vegas, complained the gambling industry was being unfairly singled out even though it generates millions in tax revenue.

Rep. Frank Wolf, R-Va., however, said Congress should draw the line at using "our constituents' hard-earned tax dollars, in these kinds of record deficits, to subsidize the rebuilding of a massage parlor, a liquor store or a casino."

The Senate bill does not contain those restrictions. The differences would have to be worked out in a joint conference, possibly in January.
It's a curious thing that the House sought to single out certain industries for exclusion. Those industries are often cash cows for states due to the excise taxes and other fees generated by liquor sales, casino revenue, and tourism dollars.

There's an interesting back and forth between Wizbang and Outside the Beltway over the article that ACoE errors led to the levee failures. It's definitely worth checking out. James Joyner at Outside the Beltway continues the discussion here. Others blogging the levee failure discussion: Conservative Outpost and Independent Sources. Noticably absent from the media coverage is the big media outlets, who are on the sidelines. One has to wonder what their motivations are to ignore and downplay a major controversy with tremendous political and economic implications.

Mister Snitch, one of the preeminent NJ bloggers, wonders why the levee story isn't getting more play in the national media. Good question. A real good question.

And now the Times Picayune is reporting that dredging may have made the flooding situation worse.
Among other problems, they say, the dredging sharply reduced the distance water had to travel to reach the canal wall; left the canal too deep for existing sheet pilings that were suppose to cut off seepage; may have removed some layers of clay that sealed the canal bottom; and reduced support for the wall on the New Orleans side.

Investigators believe the storm surge water pushed into the canal from Katrina seeped through porous soils under the floodwall, causing the earth to shift and taking the wall with it.

“The more you look at this, the worse it gets,” said J. David Roberts, the University of Missouri-Rolla professor who is an expert on levee failures, and part of the National Science Foundation forensic team. “Dredging is always a prime suspect in these failures. And when you look at this project, the alarm bells go off.”

The dredging was done as part of a joint-venture between the New Orleans Sewerage & Water Board, the Orleans Levee District, and the East Jefferson Levee District. Officials at the time hailed it as a sterling example of cooperation for the public good.
This isn't a problem that can be passed off as inadequate understanding of hydrology based on technology implemented 50 years ago. It's a failure to understand the interconnectedness of the various parts of the levee system, and that changes to one part of the system tremendously affected other parts.

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