Fix the pumps

Thursday, September 14, 2006

How long has the Corps known about the floodgate pump vibration problems?

The Times-Picayune has done yeoman work covering the construction and operation of the floodgates and pumps out at the lakefront. The latest article, from this past Tuesday, talked about continuing vibration problems on all the pumps:

"But serious vibration problems were discovered in the pumps soon after they were tested last month. The motors in 10 pumps at the Orleans canal and 12 pumps each at the London and 17th Street canals have all been rebuilt since then.
"And although some progress has occurred with the six pumps on the west side of the 17th, the results of weekend tests at London and Orleans 'weren't satisfactory,' [Corps Project Manager Jim] St. Germain said. Some pumps pulse less than others, but overall improvement is needed, he said.
"Still, he wouldn't rule out pressing most or all of the pumps into service if the canals are closed against storm surge. The faster the water leaves the canals, the faster the rainwater can drain from surrounding neighborhoods, so he said the corps would make every effort to use as many pumps as possible."

A few weeks ago, when the Corps released their totally useless initial inundation maps the Friday afternoon before the July 4th weekend - the ones with no depths shown - rainfall was dismissed as inconsequential. Here's a quote from a Corps spokesman:

"While the maps do not specify depths, a Corps spokesman said they show areas that would see inches of water and not the several feet that could result from a levee failure. 'This is a lower amount of water that's not going to be standing there for weeks like we had in Katrina,' said Todd Hornback, a Corps spokesman based in New Orleans. While the gates at the canal mouths on Lake Pontchartrain might block a devastating surge from getting in, the complication is that they will also stop some rainwater from draining. But Washington-based Corps spokesman Gene Pawlik argued that rainwater flooding is a lesser evil than flooding from another catastrophic levee rupture. 'A surge from Lake Pontchartrain is a bigger risk overall than rainfall inundation,' Pawlik said."

Now that we have inundation maps with depths that show certain areas receiving over five feet of water from rainfall backing up behind closed gates, we know the earlier reassurances to be untrue. And while it took a while, it appears the Corps is finally coming around to the common sense point of view that flooding is flooding, whether the water stays for a day or a week. That's good thing, and I applaud the Corps for coming over to the good side.

Thus the importance of the pumps at the lake. And my concern that the Corps has known about these vibration problems for months but possibly ignored them.

When the pump vibration problems were first announced four weeks ago on WLAE's "Road to Recovery," Colonel Wagenaar said the Corps was not completely surprised by them. It struck me as odd he would say something like that, because vibration problems on a new system are usually unexpected and surprising.

So I thought about why he would say such a thing. Why would they have been expecting vibration problems? The only answer I could come up with is that they had experienced them already, before the August tests. So I looked at a June 1 Times-Picayune article about pump testing. Read the article carefully. It was a little vague about what exact problems were initially encountered during a round of testing of six pumps at Orleans Avenue in mid-May, but I did learn from other sources that pumps were cavitating (sucking air and water) and generally not performing up to snuff.

I believe they were also vibrating, though perhaps not to the degree as those at 17th Street and London Ave. described by the Corps in August. Vibration would be a normal offshoot of cavitation. When combined with information I got later that seven of the ten pumps at Orleans were not working due to vibrations in recent pre-motor-replacement tests (which would definitely include at least some of those six tested in May), I think there's enough smoke to make everyone wonder about how long this fire has really been out there, and whether it was truly fully investigated.


  • Please tell me, if you can, whether the following is a valid conclusion: when a canal's hurricane gates are closed and the water level in the lake is between the canal's "safe water level" (all currently above 4ft.) and the new pumps' outlet "design" level (10ft?), all pumping out of the canal will be limited to below "design" capacity or even stopped, and, consequently, all S.&W.B. drainage pumping into the canal will be equally limited. Such a situation could last a long time, during a heavy rainfall.

    By Anonymous Malcolm Burns, at October 02, 2006 9:07 PM  

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