...the sewerage board for the pump work on Sept. 17, he says. So far, 12 big units have been dried out, he says.
Officials remain worried over the condition of the levee system. Even a modest storm surge could overtop or breach weakened areas and reflood the city. Contractors are working around the clock to repair scour and widen the plugs at breaches, whose explosive collapses created significant pits behind the levees as they failed. But restoring the entire system to an interim level of protection of at least a +10 flood stage before the next hurricane season, as compared with the pre-Katrina protection of +14, will take months to accomplish.
Gapinski says that even plugging the breaches on the big 17th Street and London Avenue canals that lead into the heart of Orleans Parish to a +8 elevation cannot be accomplished quickly enough to block immediate storm threats because damage behind the levees is so severe.
With the parallel walls on the canals compromised by the breaches and near failure of another expanse of flood wall on London Avenue near the Robert E. Lee Drive, the Corps is switching its defense to a strategy that uses temporary floodgates across the mouths of the two damaged canals. The strategy comes with a price. The gates could block a surge, but closing them also means the citys big pumps that use the canals as outfalls would have to shut down. That most likely would lead to another flood anyway.
The citys biggest pump station, No. 6, with a capacity of almost 10,000 cfs, and Pump Station No. 1, which keeps a vital Interstate highway interchange clear, would both have to be shut down if the 17th Street Canal was closed.
The Corps is draining water from the city as rapidly as it can to create a stormwater buffer, while keeping a close eye on levels of Lake Pontchartrain, which is prone to rise rapidly in storms. The Corps is pushing contractor Boh Bros. Construction Co. to refine the sheet-pile structures closing the canals so it can flip the gates open and shut quickly in a storm emergency. Boh also is laying in 42-in. bypass pumps to relieve some of the buildup if the canals have to be closed. But even a battery of four such pumps, throwing out 100 cfs each, barely begins to replace the almost 10,000-cfs output capacity of the pump station feeding the 17th Street Canal alone.
On top of an initial $50 million, Federal Emergency Management Agency officials now anticipate that the unwatering program will require another $117 million. Another $80 million has been marked for emergency work under existing coastal protection legislation.
Outer storm defenses along St. Bernard and Plaquemines parishes to the south and east also are badly damaged and would provide little protection against another big storm surge, the Corps reports. The Corps has conducted ground inspection and Light Detection and Ranging (LIDAR) surveysessentially laser-radar surveysof all levee systems. The remote-sensing data is being used to produce a detailed evaluation of the extent of loss so engineers can plan for reconstruction, first to the interim +10 level by the start of the 2006 hurricane season next June, and then "shortly afterward" to the former protection level of +14, says Brig. Gen. Robert Crear, chief engineer of the Mississippi River Division.