Gulf oil spill: Louisiana's berm plan bold but full of uncertainty

Yet the technique, which has been applied with some success on much smaller scales, hasn't been used as extensively as it envisioned to be used here. "This is one of the challenges we have: The Louisiana coast huge, and this is a humongous oil spill," she says. "Many of the techniques that have been used in more-modest spill events may have limited application at this scale."

Uncertainties about the effectiveness of berms on this scale are large, she and others note. If the project takes six to nine months to complete, for example, oil could continue to work its way into the wetlands during that period – a situation akin to closing the gate after the dog escapes.

The berms, initially planned to have tops roughly 20 feet wide and six feet above sea level, will be made from the same fine sand that makes up the Gulf's famous beaches.

"We're into the hurricane season, and even heavy surf from a distant tropical storm could tear the berms to shreds," cautions Rob Young, a geoscientist at Western Carolina University in Cullowhee, N.C., who conducts research along the Gulf Coast. Moreover, any oil-laden storm surge could mix oil into the sand as it carries both inland, depositing oil-bearing sediment.

The berms, as well as the sea floor where dredges will scoop up vast quantities of material for the berms, could alter wave and current patterns and velocities in ways that could accelerate the region's already unsustainable rate of coastal erosion, says Gregory Stone, who heads the Coastal Studies Institute at Louisiana State University in Baton Rouge. "We really need to be careful about this," he says.

Scientists suggest an alternative

He and other researchers say they are keenly aware that the BP oil spill constitutes an environmental emergency demanding quick action. But the range of potential unintended consequences gives them pause.

He and colleagues have proposed he use of booms across deep inlets, combined with building up sand dikes from the bottom of those inlets, to buy a one or two weeks' time to conduct the modeling that would help answer some of he questions about unintended consequences.

He says he's aware of the reputation academics have for moving at what can seem like a snail's pace, but the region is loaded with the computer-simulation capabilities to move very quickly in providing a more thorough analysis of the berm plan.

One of the practical questions surrounding the project is the availability of dredges and barges for gathering, moving, and redepositing the sand.

During his press briefing at the White House Monday, Allen noted that the state and BP had worked out funding issues on the project. "There are a couple of barges that are starting to work right away," he said. "But I believe the first place they're going to start working is somewhere around the Chandeleur Islands because the sand source is close enough where they can get to work right away."

West of the Mississippi River, sand will have to come from farther offshore.

"That's a much longer process," he said.

IN PICTURES: Gulf oil spill's impact on nature

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• Gulf oil spill breakthrough? Cap collecting 'majority' of oil.
• The Gulf oil spill muddle: when oil nears shore, confusion begins
• As BP oil spill spreads, 1,500 fishing boats to aid relief

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