Not good news at all:
NEW ORLEANS (AP) — Despite more than $22 million in repairs, a
levee that broke with catastrophic effect during Hurricane Katrina is
leaking again because of the mushy ground on which New Orleans was
built, raising serious questions about the reliability of the city’s
flood defenses.Outside engineering experts who have studied the project told The
Associated Press that the type of seepage spotted at the 17th Street
Canal in the Lakeview neighborhood afflicts other New Orleans levees,
too, and could cause some of them to collapse during a storm.The Army Corps of Engineers has spent about $4 billion so far of the
$14 billion set aside by Congress to repair and upgrade the
metropolitan area’s hundreds of miles of levees by 2011. Some outside
experts said the leak could mean that billions more will be needed and
that some of the work already completed may need to be redone.“It is all based on a 30-year-old defunct model of thinking, and it
means that when they wake up to this one — really — our cost is going
to increase significantly,” said Bob Bea, a civil engineer at the
University of California at Berkeley.SNIP
Over the past few months, however, the corps found evidence that
canal water is seeping through the joints in the sheet metal and then
rising to the surface on the other side of the levee, forming puddles
and other wet spots.Engineers said the boggy ground is a more serious problem than the
corps realizes. Bea said there is a roughly 40 percent chance of the
17th Street Canal levee collapsing if water rises higher than 6 feet
above sea level. During Katrina, the water reached 7 feet in the canal.John Schmertmann, a retired University of Florida professor and a
consultant on foundations, agreed with Bea that the corps “may still be
embedding some of these not-properly-considered factors, so the new
walls may not do what the corps expects.”Reducing such seepage might require the driving of sheet metal far
deeper into the ground than is done now, or some other solution, said
Bea, who was part of a team of experts sent by the National Science
Foundation to do an independent study of the levee failures during
Katrina.Donald Jolissaint, chief of the corps’ technical support branch in
New Orleans, denied the problem at the 17th Street Canal is serious.“I personally do not at all believe that this little wet spot is
anything that is going to cause a breach or a failure of any kind,” he
said. A newly installed floodgate could be used to cut off the flow of
water into the canal and reduce pressure on the levee, he said.Nevertheless, the corps is concerned enough that for weeks, workers
have been analyzing the wet spots and digging a 160-foot-long,
10-foot-deep trench to zero in on the source. “We’re doing everything
we can to chase this down,” Jolissaint said.