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Tricky maneuver: Will containment cap stop the BP oil spill?

Crews are lowering a steel and concrete containment cap over the underwater source of the BP oil spill in the Gulf of Mexico. It's a tricky maneuver, and there's no guarantee it will work.

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“We have lowered the cap to around 4,000 feet and once we have it in place will start construction of the collection pipes,” said BP spokesman Curtis Thomas. “We hope to have it operational by Monday. You’re dealing with 5,000 feet of water and very dark and cold conditions and using remote devices so you can see what’s down there. It’s a very delicate process.”

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Containment caps have been used in several oil well blowouts over the past 30 years, but extreme conditions greatly complicate this operation.

To succeed, the BP crew must contend with wreckage around the well head, the possibility of ice clogging the pipeline, a dangerous mix of oil, gas, and water that could explode, and intense fumes from the giant surface oil slick surrounding the work boats.

BP is also drilling a relief well that would shut off the blowout at its source deep in the seabed – an operation that will take months. The company is working on a third operation that would plug the blown well head from the top by encasing the failed blowout preventer with mud and concrete.

Both BP and federal officials have remained cautious in assessing the operation’s chances of success.

“I hope it works, but we are still proceeding as if it won’t,” Homeland Security Secretary Janet Napolitano said during a visit to Biloxi, Miss., Thursday. “If it does, of course, that will be a major positive development.”

Mixing oil and water

Steiner, the oceanographer from Alaska, says the slick floating in the Gulf will be very difficult to contain because the oil has so thoroughly mixed with seawater.

“The well is a mile deep and under great pressure, and much of the oil has been absorbed into the water column once it reaches the surface,” he says. “It’s also 50 miles offshore, which means it has a lot of time to be hit by waves and wind and sunlight, and is also being hit with chemical dispersants. What you’re looking at is a toxic plume of oil dispersed through the water column that is moving with the current. There may be no effective mechanical means of removing the oil.”

At the moment, the ecosystem of the Gulf’s deeper waters is at greater risk than the shoreline. The oil would at first attack the lowest end of the food chain, polluting single-cell organisms and tiny bottom-feeding creatures before affecting large organisms that feed on them.

“Polynuclear aromatic hydrocarbons such as this can also be toxic to marine eggs, larvae, and juvenile fish at one part per billion,” says Steiner.

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