London Avenue canal tests
Updated 7/28/07, see below
[For the latest on London Avenue canal testing, see my June 11, 2007 post, "Testing, testing." It has been updated quite often.]
This past Saturday, the Times-Picayune printed a detailed article about upcoming tests along the east bank of the London Avenue canal. It was buried on page 2 of the Metro section, and didn't appear online until yesterday. The article's not too long, and I strongly suggest you read it.
The gist of it is that the Corps will be isolating a 150 foot long section of the eastern wall of the canal in exactly the
They will drive a sheet pile coffer dam inside the canal to surround the area of concern. This will look exactly the same as the coffer dams driven around the breach sites, including the one still at the 17th Street breach. They will then pump water into the dammed area in a controlled manner, raising the level of water in six inch increments and letting the level stay for four hours each time. There will be lots of sensors, penetrometers, piezometers, and doo-dads to measure what the wall and levee are doing the entire time these increasing levels of water are placed against them. They'll take all that data back to the batcave in Vicksburg for analysis.
According to this article, none of this will happen until May, which is the end of the rainy season around here. Since the top reason all of this work is happening is to determine the safe water level which is acceptable for drainage from rainstorms (tropical or not), this is troubling. What's the delay? Paperwork:
"Bedey's office is pushing to get necessary agreements executed with the New Orleans Sewerage & Water Board and the Southeast Louisiana Flood Protection Authority-East to get the work started as quickly as possible."
There's no indication the T-P called the S&WB or the SLFPA-E to confirm this; they just took Col. Bedey's statement at face value.
There's also the usual Corps happy talk, again unrebutted by the T-P:
"The results of this so-called "site-specific testing" could result in a higher water level during the coming hurricane season that opens June 1, Bedey suggested.
"Even an additional six to 12 inches of water would allow the gates to remain up longer in the face of a tropical storm or hurricane. It also would allow the New Orleans Sewerage and Water Board to pump, without interference, more storm water out of the canal during a heavy, non-tropical rain event."
Of course, it's also possible that the testing could result in a lower Safe Water Level, or no significant change. That's why the testing is occurring. But of course, the Corps presents only the possibility that makes them look best. This is not how reputable engineers do things. Engineers don't assume anything before a test, for fear of skewing the results or the analysis. We definitely don't publicly hype one particular result weeks before the test even starts. But we all know what the Corps thinks of testing (see: pumps, defective).
What is also interesting about the second paragraph above is how the Corps has changed their tune now that the importance of the Safe Water Level has been revealed, via the shutoff of a 1000 cfs pump at S&WB pump station 3 during the December 30, 2006 storm, when the London Avenue SWL was exceeded. Now they say that 6 to 12 inches is very significant.
However, last September, when the four foot Safe Water Level at London Avenue was announced (it was a drop from the previously announced five foot level), they were downplaying it big time. In a September 12, 2006 article, here's what Corps pump person Jim St. Germain said:
"St. Germain would not predict just where the London canal's safe water level ultimately may be established, but he cautioned the public not to read too much into a foot or half-foot of change either way.
"It's good that the 17th went up a foot, but if London does go down, I wouldn't get too excited. We'll use the best technology we have in determining when to close those gates, but it isn't exact," St. Germain said. Only the specifics of each storm, including the rate of rise in the water level of the lake and each canal, would suggest when gates should be closed."
First off, you'll notice St. Germain is not quoted in this latest article. In fact, he seems to have gone underground since the pump testing imbroglio broke on March 13. He even gave a "no comment" to WWL-TV while escorting a Dutch delegation around the 17th Street floodgates (I watched the report, and the "member of the Corps of Engineers giving the tour" was St. Germain).
More importantly, as we now know the Corps has been very "excited" about the London Avenue Safe Water Level for a long time, including probably at the time of that September article. That is, they've known the exact location of the weakest point in the London Avenue canal walls since at least September of last year. They have allowed residents, businesses, and institutions (including Dillard University) behind those walls to rebuild for the last seven months without doing a thing to reinforce - or at least isolate - that section of wall. Instead, they've puttered around, gone out on boats to look at it, shuffled paper, and planned tests [correction, 6/1/07: see correction above for real location of load test].
Here's an idea: drive the sheet piling now, then worry about the tests later. We've already had an incident, almost three months ago (not to mention the December 21, 2006 storm, when the canal depth got within five inches of the Safe Water Level). What does it take to make these people move, an actual levee breach?
By the way, the most menacing part of the Saturday article is the last paragraph:
"Depending on the results of the field work, the corps team could decide to test the entire canal. But Bedey said it was premature to speculate on whether a test that broad will be needed."
Prepare for a test of the entire canal.
For the latest on London Avenue canal testing, see my June 11, 2007 post, "Testing, testing."