Gulf oil spill: Louisiana's berm plan bold but full of uncertainty
The plan to build 90 miles of sand berms to protect Louisiana wetlands from the Gulf oil spill is now getting under way. But it could take nine months and have unintended consequences.
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The berm plan
The berm plan, which President Obama approved last week, initially involves building about 35 miles of berms in six segments – the longest of which, off the Chandeleur Islands east of the Mississippi Delta, stretches 13 miles. In 2005, Hurricane Katrina walloped the string of islands some 50 miles long, turning them into shoals.Skip to next paragraph
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The initial berm segments are part of an overall 90-mile effort that the state of Louisiana estimates would cost $350 million to build over a six-to-nine-month period.
The use of berms "has some sound concepts behind it," says Denise Reed, who currently heads the Pontchartrain Institute for Environmental Sciences at the University of New Orleans.
First, she says, it's easier to clean up oil when it's on a sandy beach than it is to remove it from tidal wetlands. Second, well-defined channels between these temporary artificial barrier islands can serve to focus incoming oil in ways that could make it easier to corral with booms and skim.
"One of the reasons it's so easy for the oil to get into the wetlands in Louisiana is that the barrier shoreline is so degraded," Dr. Reed explains.
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.