NEW ORLEANS (AP) A 29-ft.-high (8.8 m) levee along the eastern border of St. Bernard Parish — 11 ft. (3.4 m) higher than the current levees — may be needed to protect the parish from the storm surge of a “100-year hurricane,” according to the U.S. Army Corps of Engineers.
But some parts of the levees in western New Orleans and East Jefferson are already high enough to defend against such a hurricane — one with a 1 percent chance of hitting in any given year — according to tentative elevation estimates released Feb. 14.
Along Lake Pontchartrain, the heights considered in the mid-1960s to be proof against a 200- to 300-year hurricane are enough for 100-year flood protection, the Corps said. Those levees range from 16.5 ft. (5 m) in Kenner and Metairie to as much as 19 ft. (5.8 m) in New Orleans.
The map only shows where elevations are expected to be high, and a lower but broader levee, breakwaters or other designs might provide equivalent protection, said Nancy Powell, New Orleans district chief of the corps’ hydraulics and hydrologic branch.
The numbers at least give residents, businesses and government agencies their first official look at how much levees and floodwalls might have to change to provide better defense by 2011, the date Congress and the White House have set for completing the 100-year projects.
They also will be used by the Federal Emergency Management Agency, which sets standards that levee systems must meet to qualify for the federal flood insurance program. FEMA and the corps will use them to outline flood zones within the levees, and new, permanent rules for how high new and renovated buildings must be built.
Officials say it is not yet clear which sections of the new levee system will require rock, concrete or geotextile fabric “armor” to protect their inner sides from erosion caused by surge and wave overtopping during a hurricane.
The Bush administration has included $460 million for armoring in the $5.7 billion it has included in its fiscal year 2009 budget request to complete construction of the 100-year levee system by 2011. The corps already has about $170 million set aside from earlier appropriations for armoring.