More New Orleans Revelations

--Sebastian

This story is old news by the standards of the current news cycle but is well worth looking into as the investigation continues (from the LATimes):

The levee breaches along two major canals that flooded New Orleans after Hurricane Katrina resulted from massive soil failures under concrete storm walls, not from hurricane surges that sent water over the tops of the walls as Army officials initially said, according to teams of investigators who have examined evidence in the last week.

The findings appear to chip away at the simple story that the storm surge was much larger and higher than the walls were designed to handle, though investigators caution that it is too early to blame design or construction.

"No question there was soil failures," said Peter G. Nicholson, a University of Hawaii engineering professor who is leading an investigation for the American Society of Civil Engineers. "But we can't speculate whether it was a construction, material or design flaw."

If soil problems are widespread in New Orleans' 350 miles of protective levees, then upgrading the system to protect against hurricanes more powerful than Katrina could require a major investment.

Immediately after the storm, the Army Corps of Engineers thought that a surge from Lake Pontchartrain had moved up drainage canals in the city and overflowed concrete storm walls, eroding foundations and leading to the breaches.

Investigators have found no evidence of such overflow and foundational scouring at the breaches in the London Avenue and 17th Street canals, two main failures behind the central New Orleans flooding. In fact, in one case, water marks are a full 2 1/2 feet below the tops of the walls.

Instead, investigators have found strong evidence that the soil structure was too weak for the pressure of the water, wind and waves.

Soil failure is like pushing on a chocolate cake that is sitting on a plate: At first the cake sticks to the plate, but if you push hard enough the gloppy structure eventually moves, said Raymond B. Seed, an engineering professor at UC Berkeley who is leading a separate National Science Foundation investigation of the levee breaches.

So far, Seed thinks the failure of the soil structure initiated the breaches at London Avenue and 17th Street. The levees were constructed on "particularly unfavorable" foundations of organic peat, which is both compressible and weak, he said.

The teams from the National Science Foundation and the American Society of Civil Engineers are expected to produce preliminary reports in weeks; the Army Corps of Engineers, which designed and built the levees, expects to issue its own formal report next year. The three groups are conducting separate investigations but have shared fact-finding and technical data gathering over the last week.

All three are examining a range of other failures over miles of levees in and around New Orleans. The teams have identified at least 25 breaches, most of which happened when storm surges washed over the levee tops and badly eroded the earthen structures.

Those failures are not getting as much attention, because they occurred in less-populated areas that were largely evacuated before the storm. So many kinds of levees exist in so many locations that the investigations are probably going to find many causes for levee failure.

"There aren't a lot of simple answers," Nicholson said. "That is the truth of it."

But central New Orleans was flooded by breaches along the two canals. In those cases, masses of earth shifted, said Paul Mlakar, a scientist at the Army Corps of Engineers who is leading the corps' investigation. Along the London Avenue canal, he found that a 100-foot-long block of soil, about 15 feet deep, was pushed back 35 feet.

As the earth berm shifted, the concrete storm wall on top collapsed into the hole left by the moving soil and disappeared into the water, Mlakar said. In some cases, evidence of the levee breaches has been buried under the emergency repairs made immediately after the hurricane.

Only one canal, the Inner Harbor Navigation Canal, showed signs that water levels rose over walls, and it is not clear whether that caused the levee to fail, Mlakar said. A shipping barge did break loose from its mooring and may have rammed the wall, though investigators say it is too soon to know whether that caused the failure.

Engineering experts have offered numerous theories about the failures, saying the walls were improperly designed, the soil strength was miscalculated, and the levees were improperly maintained under the authority of the local levee district.

But Seed, Mlakar and Nicholson said they had not completed an analysis of whether Katrina exceeded the design strength of the levees. Seed noted that hurricanes, like earthquakes, could impose sharply different loads from one location to another. Levee loads were affected by the water depth, but also by wind and waves against the storm walls.

This suggests that the kind of strengthening of the the levees being talked about before and immediately after Katrina may have been inadequate to protect New Orleans.  If a significant portion of the levee system is subject to this problem, not only will the levees need to be made higher and wider, the levees will also need to be overhauled from top to bottom.  Considering the danger the Mississippi River Project also poses to New Orleans, and the fact that (according to the Army Corps of Engineers) the river will almost certainly shift dramatically in the next 50 years (and in fact would have already if the Corps weren't spending so much effort to keep the river in its current course) thus changing the mouth of the River in the gulf and requiring a new port location, I hope we think long and hard about whether or not rebuilding New Orleans is a worth-while project.  I'm not saying that it is not.  But I am saying that rebuilding it just to keep God from winning, isn't reason enough. 

Comments

[CMatt]

For a believer, attempting to keep God from winning would seem something of a sucker's bet.

Meanwhile there are the underpinnings of the entire Midwestern and central Southern economies to consider. Plus oil and natural gas. If we're simply considering the bottom line.

If that's not the entirety of it, and it shouldn't be, a few moments reflection on the phrase, "There but for the grace of God go I" might prove beneficial.

[Anarch]

For a believer, attempting to keep God from winning would seem something of a sucker's bet.

And on that note, Wilma's been upgraded to a Category 4 hurricane and is expected to hit Cat5 by the morning. Stay safe, south Florida, 'cause you could be in for one hell of a ride.

[Tim]

Actually they should rebuild and start building the next port, which will probably become mandatory in the next twenty years. No business would ever do that unless their existing infrastructure was completely destroyed; so that would mean higher taxes, which means everyone is only going to look at the immediate crisis lest they see something they don't like.

[Slartibartfast]

Well, there are a few options. I doubt if any of them are even on the table, but:

1) Make New Orleans into a sort of Venice of the New World. Put all the buildings up on pilings, and have gondolas and walkways for transportation, instead of the streetcars.

2) Bring in several million Jesus-loads of crushed rock and gravel and bring the city up above sea level. Build on that.

3) Move New Orleans to a different location.

4) Just bag it.

I kind of lean toward #1, myself. Of course, passing out in the gutters could be fatal, but people will just have to adapt.

[notyou]

Of course, passing out in the gutters could be fatal, but people will just have to adapt.

Lifevests to go along with the beads.

[Dantheman]

"Bring in several million Jesus-loads of crushed rock and gravel..."

So how much gravel can one Jesus hold? And how many angels can dance on that many pieces of gravel?

[Charles Bird]

Well, so much for Farrakhan's little theory.

[Edward_]

I'm all for a Venice in the Delta approach.

I'm already considering what type of gondola to buy for my Soho Apartment, expecting global warming to drown the first two floors of my building, leaving me with a nice waterfront home.

[calmo]

Charles, could be that the Minister's views and the civil engineering report detailing the soil structure failure can both be substaniated.
I like Slarti's options and think we (the people) are with his/her choice of #1. (Maybe #2 if those Jesus trucks can be found).
That is, we are in denial. We are in denial about GM and Iraq and... It is sometimes a good recovery strategy: "What problem?" allows you to atleast get to your feet before the real depth of the disaster hits you right between the eyes.

[Slartibartfast]

Jesus-load was, as far as I know, first used by Spider Robinson in Time Pressure, if memory serves. Googling jesus-load yields some interesting, informative and occasionally tragically funny results.

[calmo]

U B right, my transgression: Jesus-load sized trucks rather than the lighter Jesus trucks.

[Jackmormon]

I'm sorry to rain on the parade of bipartisan daydreaming here, but isn't the original Venice slowly sinking into its lagoon, requiring constant salvaging operations? I can't imagine that such fragility would do very well in a hurricane zone.

I'm voting for the Jesus-loads.

[Mo MacArbie]

1 metric Jesusload is 1/1000th of the volume of the Dead Sea.

[dmbeaster]

This suggests that the kind of strengthening of the the levees being talked about before and immediately after Katrina may have been inadequate to protect New Orleans.

No -- this inference is almost certainly wrong. The fact that older structures fail is not a good basis for infering that they cannot be made safer, or that modern designs cannot avoid the pitfalls of older structures.

Its dull to talk about, but this type of failure of a dam or levee structure (hydrosatic pressure causing failure) is not surprising, and is well understood.

It is one of the more common causes of levee failure, rather than due to erosion from being overtopped. The pressure undermines the original foundational soils rather than the levee material itself. And it is difficult during construction to calculate the strength of the underlying soils which, by definition, cannot be known with certainty.

The better assumption is that they can engineer adequate levees even in the difficult soils of the Mississippi River basin -- its all a matter of cost. (The levee at St. Louis withstood a 52 foot flood stage in the Great Flood of 1993). And that the old levees are trouble-prone because they were built inadequately when the engineering knowledge was inadequate, just as with older buildings that lacked adequate protection from earthquakes.

Just ask the Dutch, who have built superb levees that withstand far more strain than that imposed on those in New Orleans. It can be done -- whether its worth it is another story.

[Jesurgislac]

And more revelations about New Orleans, via Jeanne at Body and Soul.

BE&K landed a subcontract to help rebuild the naval air station, it turned to Knight for electricians -- he says 75, BE&K says 59 at the peak of work.

BE&K was working for Kellogg, Brown & Root, a subsidiary of Halliburton Co., Vice President Cheney's former company.

When BE&K came to him, Knight said he was told his work would run well into the millions of dollars and stretch out as long as 20 months. His men would be paid the prevailing union wage of $22.09 an hour, plus health benefits.

After three weeks, the initial work was 60 percent completed. Then, on Friday, Knight received a letter informing him that BE&K workers -- largely from out of state and, according to Knight, earning $14 to $15 an hour without benefits -- could take over from there. link

Just like Iraq, isn't it?

[Freder Frederson]

Please don't confuse the Mississippi River levees, which in every instance held, even when they were overtopped by the storm surge (not in New Orleans, but much further downstream near Venice, LA) and the Lake Ponchatrain and canal levees which failed in New Orleans (along with the marsh side levees which failed in lower Plaquemines and St. Bernard Parishes and caused the massive flooding there). They are two entirely different things designed for two entirely different events.

When you live in New Orleans, as I do, most of the rules of the rest of the world, even the very laws of nature, are suspended. The highest point in New Orleans is the Mississippi River levees which are 20 to 22 feet above sea levee. Most of the time the river itself is higher than the city. After living here a while you get used to seeing ocean-going ships going along the river above you. Since the sewage treatment plant is in high spot in the city on the river bank, shit literally flows uphill in New Orleans. Directions are meaningless, the "West Bank" is alternately east, south, and west of New Orleans; The "North Shore" is not only north, but also east of the city. New Orleans is already the American Venice. It has more canals than Venice, it's just that most of them are buried, but its network of pumps and canals push water into Lake Ponchatrain 24 hours a day to keep the city dry.

The flood threat from the Mississippi is well contained and is mostly an upstream threat. Upstream of New Orleans there is a diversion canal that can be opened to divert floodwaters from the Mississippi into Lake Ponchatrain so they don't have to blow up the Levees south of the city like they did in 1927. The threat of a storm surge on the Mississippi River side of New Orleans is minimal because New Orleans is 120 miles from the mouth of the Mississipi River (get your map out).

No the real nemisis of New Orleans is Lake Ponchatrain and the levees that protect the city from the storm surge coming from the lake. Lake Pontchartrain is about 5 feet above sea level and the lakeside levees are supposed to be at a consistent 17 feet. Even if they were properly built and maintained (which everyone knew they were not), the levees were inadequate to protect against a direct hit by a Cat 4 storm or even a slow moving Cat 3. When President Bush said no one anticipated a levee breach he was either lying or incredibly ignorant. You can decide which is worse.

There are many ways to restore New Orleans, protect it against a Cat 5 storm, maintain shipping, restore the wetlands in Southern Louisiana, and do it all in an environmmentally senstive way. All it takes is a little imagination, the political will, and the resources. It won't be cheap, but it will be a hell of a lot less expensive than the 100s of billions of dollars that we will spend recovering from Katrina and it won't kill over 1000 people to achieve it.

The disaster in New Orleans was 100% avoidable for an investment of somewhere in the neighborhood of $25 billion (and a lot of this cost is to correct the mistakes the Corps has made over the last 80 years). We just lacked the political will to do it.