Friday, February 09, 2007

New Orleans Levy System Still Crumbling

Citizen journalism being done by blogger mcbrid35

On Dec. 30th, 2006, New Orleans experienced a relatively slow, steady rain most of the day and evening. Near the end of that storm, as the rain was pumped out along the London Avenue canal (site of two breaches in Katrina), the water rose above a depth in the canal called the Safe Water Level. In the London Avenue canal, that depth is a mere four feet above sea level (Lake Pontchartrain - at the end of the canal - is at sea level). That level is dictated by the extreme weakness of a stretch of unbreached canal wall just south of Mirabeau Avenue. In practical terms, this means that the water in the canal is not even allowed to touch the walls that top the levees. For most of the canal's length, the tops of the levees (i.e. the bases of the walls) are above four feet. The tops of the walls are over 14 feet above sea level.

So when the water rose above four feet, the local drainage agency, the New Orleans Sewerage & Water Board, called the Corps, who dispatched their pumping guru to the pumping station (station 3) that drains the water into the London Avenue canal. He agreed that the water depth, which can now be seen by virtue of a new set of level sensors installed along the canal, was unacceptably high and that something needed to be done.

There is only one thing that can be done to drop the water level in the canal in a situation like this: cut back on the amount of water going into the canal. So that's what was done. There are five pumps in station 3, and one of them, a 1000 cfs pump representing almost a quarter of the station's capacity, was shut off. It was kept off for a half hour until the water in the canal dropped to an acceptable level. This reperesented water not being drained from the streets of New Orleans during that time. Fortunately, the rain had mostly let up by that time and there was no serious flooding. But the worst was yet to come...


Much more over at Fix the pumps.

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