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MRGO as the "express lane": Part 2

Katrina may mean MR-GO has to go

...After massive flooding killed hundreds in St. Bernard Parish, eastern New Orleans and the Lower 9th Ward, there is growing consensus that Katrina's surge was made far worse by the Mississippi River-Gulf Outlet, a 76-mile shortcut between the city and the Gulf of Mexico. And while the shipping industry vows to protect the channel, political momentum appears increasingly in favor of St. Bernard officials who have long warned the waterway must be closed.
Scientists from Louisiana State University's Hurricane Center say the Gulf Outlet, also known as MR-GO, and a second channel, the Intracoastal Waterway, funneled Katrina's powerful surge into a narrow bottleneck just north of Chalmette.
The funnel caused floodwaters to stack up several feet higher than elsewhere in the metro area and sharply increased the surge's speed as it rushed through the MR-GO and into the Industrial Canal. As a result, levees that would have been topped -- but not breached -- crumbled under the hydrologic assault, turning a major flood into an unprecedented disaster, according to Hassan Mashriqui, a civil engineer from LSU who had predicted the funnel effect prior to the storm.
Absent the funnel effect, Mashriqui said, "you would have had maybe 2 to 3 feet of flooding at the max, but not everybody's house underwater. It's still flooding, but one is significant and one is catastrophic."
The Port of New Orleans and Army Corps of Engineers dispute the Hurricane Center's claims, saying Katrina's intensity was enough to topple levees regardless of the shipping channel. Those levees were built to withstand only storms up to Category 3; Katrina made landfall at Buras as a Category 4 storm.
"This was just a ferocious and huge storm," Port of New Orleans CEO Gary LaGrange said.

Previously: MR-Gulf Outlet canal under scrutiny; "express lane" for the surge

Jackson, ACE on the Industrial Canal and the barge

From this:

[Jesse] Jackson believes a big barge crashed through the floodwall here [Industrial Canal], bringing the tidal surge into this neighborhood, causing the devastation.

According to Ernest Murry from the Army Corps of Engineers, everything - including who owns the barge - is still up in the air. The barge has an ID #, but they don't know why it was there during the storm. And, from Murry: "My theory is the barge came through after the wall fell".

The Army Corps of Engineers said the sheet pilings for the flood wall on the Industrial Canal were driven 20 feet deep. That's what engineers specified to protect the area from a category-3 hurricane.
As crews continue to make repairs, Murry said he thinks water came over the top of the floodwall, undermining the levee.
The Army Corps of Engineers said it does not know who owns the barge that came crashing through the neighborhood during Hurricane Katrina.
"It eroded all the ground on the backside of the wall and then the wall just collapsed over," Murry said, pointing out one of two breaches on the east side of the Industrial Canal.
But why, Jackson asked, was that barge in this canal as a category-4 hurricane made landfall?
"When they anticipate a hurricane coming, don't they move barges further away from the possibility of this kind of collision?" Jackson said as Murry nodded in agreement.
When the barge did come through, Murry said it landed on top of some homes.
"Actually, it was about 30 feet over…during Katrina. And then when Rita came through, it floated through again and came over this way," he said.

Previously: Did a barge cause the Industrial Canal breach? and Did barges cause the floodwall breaches?

Louisiana's seafood industry devastated; MRGO, environmental damage

The DMN's "Seafood industry forced over the edge" reports that the $2.6 billion a year industry has been severely damaged by both hurricanes:

...That has heightened uncertainty about the future of an industry that provides nearly 30,000 jobs and lands almost half of the shrimp, 26 percent of the crabs and 37 percent of the oysters caught in the United States...
Oystering - an industry built on leasing reefs on which oysters are planted and harvested like land crops - already had been hurt by saltwater intrusion from the Mississippi River Gulf Outlet, a controversial 76-mile canal constructed in 1968.
The channel, known as MRGO, was designed to shorten the distance that deep-water transport ships had to travel to reach New Orleans from the open waters of the Gulf.
It also may have provided a devastatingly efficient pathway for Katrina's enormous storm surge.
St. Bernard Parish and much of Plaquemines Parish, the state's two biggest seafood producers, were covered in 12 to 14 feet of water, and much of both parishes' fishing fleets were pushed onto nearby roads, bridges and levees. The storm pushed huge amounts of mud and debris that smothered oyster beds, damage that experts say will take two years or more even to begin to undo.
Shrimping grounds were littered with debris. Boats reported seeing animal carcasses and shredded bits of buildings as much as 100 miles into the Gulf.
The U.S. Geological Survey says that before Katrina, Louisiana was losing almost 44 acres a day of the marshlands that serve not only as coastal buffers but also as nurseries for the state's fisheries. The USGS now estimates that the hurricane obliterated nearly one and a half times the amount of Louisiana marshland eroded into the sea over the previous 48 years...

Did barges cause the floodwall breaches?

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.

LSU: Faulty design or construction of floodwalls to blame

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.

And:

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."

Lowry on the levees, MRGO, and the floodwalls

From "What caused the flood? Take your pick":

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...

MR-Gulf Outlet canal under scrutiny; "express lane" for the surge

The NYT article linked in "St. Bernard Parish defenseless from storms til 2006" also includes this:

[St. Bernard Parish], which unlike New Orleans lies above sea level, was protected by the levee from the Mississippi River-Gulf Outlet, a canal built by the corps that is now a subject of scrutiny. Completion of the canal four decades ago allowed saltwater intrusion that, the corps acknowledges, was a factor in the death of marshes that once helped protect the city from storm surges. Some experts say the canal may also have provided an express lane for the Aug. 29 surge to reach populated areas.

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