80 miles of sand berms???? Experts express doubts.......

[Note that there is now a follow-up post to this, documenting the approval of this plan, together with commentary from US Government Agencies and a summary of a detailed report on the sediments of the Chandeleur Islands]

Louisiana. The President of Plaquemines Parish has presented a plan for dredging and construction of eighty miles of six-foot sand berms along the coast on either side of the Mississippi Delta as protection against the oil spill (the original plan had been for twenty-foot berms). The illustration above is from the plan as published online. This was described in a New York Times article a couple of days ago, and I have taken the liberty of reproducing the bulk of the article here (I left out BP’s comments since I felt that they were hardly objective):

Experts Express Doubts on Sand-Berm Proposal

By JAMES C. McKINLEY Jr. and JOHN COLLINS RUDOLF

Published: May 21, 2010
VENICE, La. — State officials here are imploring the federal government and BP to build 80 miles of sand berms and plug holes in barrier islands in a desperate effort to stop oil from the Deepwater Horizon spill from destroying marshes, sounds and bayous.
But many experts say it is not at all clear whether dredging companies could build up the barrier islands quickly enough to save the marshes. They are also concerned that the kind of sand berms envisioned in the plan might wash away quickly after a couple of storms, wasting scarce sand in the region.
Still, Gov. Bobby Jindal and local officials say the berms represent the state’s best hope of protecting the fragile Mississippi Delta and its fisheries. The officials are frustrated with what they see as bureaucratic inaction. “They haven’t given us any reason for the delay,” Mr. Jindal said Wednesday.
So far, the Army Corps of Engineers has not granted the state’s request for an emergency permit for the plan. The Coast Guard, which can force BP to pay for a $350 million dredging project, has yet to make a decision about it.
For several years, the state has been trying to get financing for a similar project to rebuild the Chandeleur Islands, a chain of low-lying barrier islands in the delta that lost more than 80 percent of their surface area during Hurricane Katrina in 2005. But officials say they are not simply taking advantage of the oil spill to finance a long-hoped-for project.
Billy Nungesser, the president of Plaquemines Parish, who has been pushing for the sand-berm project, said he hoped BP would pay the cost of building what amounts to a six-foot seawall over the next six months. The state’s earlier plan had called for the islands to be rebuilt to about 20 feet above sea level.
At stake, Mr. Nungesser said, are Louisiana’s seafood and sport-fishing industries. “If we don’t do something, shame on us,” he said.
On May 11, the state Coastal Protection and Restoration Authority of Louisiana requested the permit from the Army Corps of Engineers to create the barrier in the Gulf of Mexico out of sand dredged from a site several miles offshore. The barrier would stretch along the coastline on both sides of the Mississippi Delta, from Chandeleur Sound in the east to Barataria Bay in the west.
Gregory W. Stone, director of the Coastal Studies Institute at Louisiana State University, said that dredging and pumping large amounts of sand amid Louisiana’s complex inlets and bays could harm ocean life. Dr. Stone said any plan required closer study before it is put in place.
“I understand that time is of the essence, but I really think that we’re taking a gamble here,” he said.
The general idea of protecting the area’s vulnerable wetlands by buffering coastal islands with dredged sand is not particularly controversial. Similar plans have been in the works for years, and small-scale projects have had success in the recent past.
“The concepts behind this are probably sound,” said Denise J. Reed, a wetlands expert and interim director of the Pontchartrain Institute for Environmental Sciences at the University of New Orleans. “One of the reasons we’re so worried about the oil coming into the marshes is the barrier islands are so degraded. We don’t have a very intact shoreline.”
The governor’s plan would not permanently rebuild degraded coastal islands — a delicate and complex process that has been planned for years. A temporary sand barrier could wash away in a matter of months, experts said. And the type of sand necessary for long-term coastal restoration is in short supply along Louisiana’s shoreline.
“If we use the good sand that we have for this quick-and-dirty berm, and a storm comes in and spreads it around, we’ve lost the major sand resource that we wanted to use for barrier-island restoration,” Dr. Reed said. “We could compromise the long-term restoration of the coast for a short-term gain.”
Right now, the chain of barrier islands has very little protection. Asbury H. Sallenger Jr., an oceanographer with the United States Geological Survey, said the Chandeleur Islands lost the majority of their surface area during Hurricane Katrina. Even a strong wind can push a surge of water over the island, he said.
But Dr. Sallenger, like other experts, noted that the dredging project would take months to complete, and the oil is already showing up in the marshes. “My first question is whether such a thing could be done, from a scientific basis, quickly enough to be useful,” he said.
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State officials acknowledge there are concerns about environmental impacts from building the berms. A number of barrier islands that would be built up by the dredging operation are sensitive habitats for turtles and other species, and some are protected bird sanctuaries. Heavy construction could further disturb these populations, which are already under threat from the oil slick. But they are willing to take that risk, given the potential damage the oil slick could cause.
Still, a spokesman for the Army Corps, which will oversee the permit process, said that even under an expedited basis, the dredging project would need to comply with federal environmental regulations.
Mr. Nungesser said the proposal did not need more than a few days’ study. Similar projects have been extensively reviewed by local experts in coastal restoration, he noted.
“It’s not something that we dreamed up overnight,” he said.

I really don’t know where to begin, since there are so many extraordinary aspects to this idea, several of which have been commented on in the article. The total cost is listed as $235 million, but there is no clear mention of how much sand would be required, where it would come from, its compatibility with its new environment, and how long it would take – never mind how long it would last. On the latter point, just for the record, it’s worth pointing out that the plan’s satellite image (at the head of this post) clearly predates the almost complete disappearance of the Chandeleur Islands that curve north from the delta; as I have commented before, barrier islands are amongst the most dynamic and ephemeral natural landforms on the planet, and those, like the Chandeleur Islands, that have been starved of sediment supply by human interference are particularly vulnerable. The wonderful historic imagery facility on Google Earth demonstrates this dramatically. Below (north to the right) are images from progressive dates from 1998 to 2009, the arrow registering the same point in each. During that period, nine hurricanes hit the Louisiana shoreline – Frances, Georges, Lili, Ivan, Katrina, Humberto, Gustav, Ike, and Ida. The most devastating was, of course, Katrina whose destruction of what was left of the islands can be seen in the 2005 images.