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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...

Feds trying to scapegoat Sierra Club?

Remember the posts "Greens vs. Levees" or "New Orleans: A Green Genocide"? It looks like the feds might have been reading those articles:

The Clarion-Ledger has obtained a copy of an internal e-mail the U.S. Department of Justice sent out this week to various U.S. attorneys' offices: "Has your district defended any cases on behalf of the (U.S.) Army Corps of Engineers against claims brought by environmental groups seeking to block or otherwise impede the Corps work on the levees protecting New Orleans? If so, please describe the case and the outcome of the litigation."
...The Sierra Club and other environmental groups had nothing to do with the flooding that resulted from Hurricane Katrina that killed hundreds, [David Bookbinder, senior attorney for Sierra Club] said. "It's unfortunate that the Bush administration is trying to shift the blame to environmental groups. It doesn't surprise me at all."
...[Contrary to what the NRO article says,] The levees that broke causing New Orleans to flood weren't Mississippi River levees. They were levees that protected the city from Lake Pontchartrain levees on the other side of the city...

Why did the floodwalls break and not the levees?

From this:

One of the central mysteries emerging in the Hurricane Katrina disaster is why concrete floodwalls in three canals breached during the storm, causing much of the catastrophic flooding, while earthen hurricane levees surrounding the city remained intact...
"Why did we have no hurricane levee failures but five separate places with floodwall failures?" asked Joseph Suhayda, a retired LSU coastal engineer who examined the breaches last week. "That suggests there may be something about floodwalls that makes them more susceptible to failure. Did (the storm) exceed design conditions? What were the conditions? What about the construction?"
Ivor Van Heerden, who uses computer models to study storm-surge dynamics for the LSU Hurricane Center, has said that fragmentary initial data indicate that Katrina's storm-surge heights in Lake Pontchartrain would not have been high enough to top the canal walls and that a "catastrophic structural failure" occurred in the floodwalls...

Technical info on repairing levees

Sep. 2's "Repairing Levees, Getting the Water Out" has more:

...The Army Corps of Engineers learned that the [17th Street Canal levee or flood wall] had broken early Monday even as the storm hit, but it was impossible to do anything about it before lake water cascaded unimpeded into the below-sea-level city for 36 hours, turning a really bad storm into an unimaginable abomination. There was no public announcement that the levee had broken until late Monday.
Lt. Gen. Carl A. Strock, the Corps' commander, told reporters at the Pentagon on Friday that Katrina had simply overpowered levees designed 30 years ago with a 99.5 percent chance of enduring for 200 to 300 years: "We, unfortunately, have had that 0.5 percent" happen, Strock said.
On Friday, the Corps was trying to close the 17th Street breach and another breach at London Avenue to the east. A third break -- two breaks actually -- in the Industrial Canal, were left alone because water levels in the lake and the surrounding wetlands had subsided so much that water was draining out instead of coming in.
Col. Richard P. Wagenaar, the Corps' New Orleans District commander who is the on-site commander at 17th Street, said a police officer called him Monday morning to tell him about the break, but he could not drive there. On Tuesday, the Corps tried to drop some sandbags into the breach, but "it didn't work real well," Wagenaar said. "They were too small, and the water velocity carried them away."
It was better on Friday, but there was a big, deep hole to fill, and the bags -- made to hold 20 tons of sand -- were only carrying five, because the helicopters that arrived every five minutes or so, Black Hawks, Sikorskys and even the Chinooks, could not haul more.
Still, the Corps had a plan. Michael Zumstein, action officer for the Corps' "unwatering team," said the canal had been sealed off from the lake with steel slabs, causing water levels in the canal to drop further. That should eventually make it easier to plug the breach.
While the preferred strategy was to plug the breach and allow the city's pumps to discharge floodwater into the canal, the Corps was also prepared to use emergency pumps to flush directly over the steel dam and into the lake if stopping up the hole proved too difficult.
Zumstein said engineers were using the same strategy at a 250-foot breach in the London Avenue Canal, where they were closing the canal mouth even as they tried to stopper the hole: "They're tearing up Lakeshore Drive and using the concrete as fill," Zumstein said.
Elsewhere, flood teams were taking advantage of the fact that the city is divided by internal levees and floodwalls into 13 "sub-basins" with their own drainage systems and pumping stations -- like separate basements with their own sump pumps.
Walter Baumy Jr., engineering chief for the Corps' New Orleans District, said water levels in the lake had subsided by mid-afternoon Friday to within a foot of normal levels, and "when the water inside the bowl is higher than the lake level, we want to drain the water out of the bowl as much as possible."
Baumy said engineers planned to cut new breaches, or "notches" in levees elsewhere in the city, creating makeshift gutters in flooded areas to let water leak out. "We'll see an immediate improvement," he predicted...


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