(PHOTO: Tyrone Turner/National Geographic Magazine)
The NYT has an article today on the “signs of serious flaws” in the levees of New Orleans. It is based on a feature by National Geographic and that is the must read.
During a recent inspection of the levee system with National Geographic
Magazine, engineering professor Bob Bea of the University of
California, Berkeley, found multiple weak spots. The most serious flaws
turned up in the rebuilt levees along the Mississippi River Gulf Outlet
ship channel, which broke in more than 20 places when Katrina’s storm
surge pounded it, leading to devastating flooding in the Lower Ninth
Ward and St. Bernard Parish. Bea found several areas where rainstorms
have already eroded the newly rebuilt levees, particularly where they
consist of a core of sandy and muddy soils topped with a cap of
Mississippi clay. “It’s like icing on the top of angel food cake,” Bea
says. “These levees will not be here if you put a Katrina surge against
them.”Bea also found that decade-old gaps remain in the
floodwalls lining the Orleans Avenue Canal, and hurricane-damaged
sections of the walls along the London Avenue and 17th Street Canals
have not been repaired or replaced. Even more troubling, water appears
to be seeping under the stout new floodwall erected along the
Industrial Canal to protect the Lower Ninth Ward. The new wall sits
atop steel sheet piles driven 20 feet into the ground, but water from
holes in the canal bed, excavated before Katrina or scoured by the
storm, may be seeping under the barrier through permeable layers of
sand and silt. Bea, who actually tasted the seepage to make sure it was
brackish—a sign that it was coming from the canal—says the wall could
fail in the next hurricane.Bea,
co-leader of a Berkeley team that investigated the Katrina levee
failures, is now serving as an expert witness in a multi-billion-dollar
class-action lawsuit against the corps. But he is not alone in his
criticisms. A Dutch engineer recently visited some of the new
floodgates and pumps installed at the mouths of the city’s three main
drainage canals. His verdict: They may be “doomed to fail” in the next
big storm.
National Geographic has an excellent VIDEO ofaerial footage showing the flaws. There is another VIDEOof Bob Bea warning it is not yet safe in much of New Orleans. When asked if the city will flood again in the near future he responds…”Yes without a doubt.”
UPDATE 5/8/07: You can go HEREto see photoswe took on our recent trip to NOLA of repair work to one of the major breaches New wall and armoured levee sits right next to old wall and apparent erosion of levee.