Photo Credit: US Army Corps of Engineers, Mississippi Valley Division
More Hurricane Katrina images are available in BBSNews Photos.
Army Corps of Engineers Still Battling Levee Break
USACE via BBSNews - 2005-09-04 Mississippi Valley Division -- At the 17th Street Canal, the Corps of Engineers first attempt to stop water from entering through the breach was to fill in the breach itself and keep the canal mouth open for access and drainage. When breach repairs were first attempted, Lake Pontchartrain was still several feet above normal level. Rapidly sealing the mouth of the canal would have trapped elevated flood water inside the city.
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| Flood Wall Break, New Orleans. Photo Credit: US Army Corps of Engineers, Mississippi Valley Division |
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More Hurricane Katrina images are available in BBSNews Photos. |
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During detailed survey of the damaged levee, engineers discovered other still intact but potentially weakened sections. During this period, the lake fell to normal levels so no further gravity drainage back out of the city was possible. Because of this, and the relatively slow process of filling the large levee breach, engineers decided to change strategies and use marine equipment to drive sheet piling at the mouth of the 17th Street canal to seal off the entire canal from the lake.
Both operations were executed in parallel through yesterday when we achieved final closure of the canal mouth with sheet piling. The final piling was not driven until the Corps was confident that the lake had fallen to a normal level and water was not trapped inside the city that would otherwise drain out by gravity.
With the mouth of the canal sealed, the sheet piling prevents lake water from getting to the levee breach. Since no additional water can get through the breach it is no longer necessary to seal the breach itself. The next step is to get existing pumps working, and to bring in additional pumps to drain the surrounding city and the canal. Once the canal is drained permanent repairs will be made to the levee.
With the 17th street canal sealed against further flooding, the priority effort is to seal the London Street canal and other areas where gravity drainage is no longer possible.
Five pumps ordered yesterday are being delivered piecemeal to a staging area in St. Rose, where they will be partially assembled and deployed to the 17th Street Canal and London Avenue Canal for final assembly and startup. The first of the deliveries was yesterday afternoon, and the remainder were expected throughout the night and into today.
Four more pumps are being loaned to the Corps by St. Charles Parish and have been deployed to the 17th Street Canal for final assembly.
Arrangements have also been made to acquire two large mobile generators to power the pumps at Pump Stations #6 on the 17th Street Canal and Pump Station #7 on the Orleans Avenue Canal.
Navigation Status
The Corps of Engineers is working to arrange the salvage of two objects found in the bar channel at the mouth of Southwest Pass of the Mississippi River. Southwest Pass is the channel used by ocean-going ships. The bar channel is a navigation passage dredged in open water of otherwise insufficient depth.
The obstructions have not been identified. Fortunately they are more than 40 feet beneath the surface. This depth means that river traffic may continue at the current restrictions, which permit only vessels drawing 35 feet of water or less.
The obstructions were found by a survey vessel of the National Oceanic and Atmospheric Administration (NOAA). The obstructions are located a little more than one-half mile from the end of the Southwest Pass jetty.
USACE is the US Army Corp of Engineers. The US Army Corps of Engineers is working in the areas affected by Hurricane Katrina, including Alabama, Florida, Louisiana, and Mississippi.
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