Coast Guard will start burning thickest oil patches in Gulf slick from rig explosion off La.

Coast Guard will start burning some Gulf slick oil

NEW ORLEANS — Racing against a threat to environmentally sensitive marshlands, authorities planned to begin Wednesday burning some of the thickest oil from a rig explosion off the coast of Louisiana.

A Coast Guard spokesman says the burn was expected to begin in the morning.

Petty Officer 2nd Class Prentice Danner says fire-resistant containment booms will be used to corral some of the thickest oil on the water’s surface, which will then be ignited. It was unclear how large an area would be set on fire or how far from shore the first fire would be set.

The slick is the result of oil leaking from the site of last week’s huge explosion of the rig Deepwater Horizon that left 11 people missing and presumed dead.

Oil continues to spill undersea at an estimated rate of 42,000 gallons a day.

Robot submarines have been unable to cap the well. Operator BP Plc. says work will begin as early as Thursday to drill a relief well to take pressure off the flow from the blowout site. That could take months.

Winds and currents in the Gulf have helped crews in recent days as they try to contain the leak, but it has moved steadily toward the mouth of the Mississippi River, an area home to hundreds of species of wildlife and near some of the Gulf’s richest oyster grounds.

Meanwhile, the cost of the disaster continues to rise.

The Deepwater Horizon exploded on April 20. The rig was owned by Transocean Ltd. and operated by BP.

Industry officials say replacing the Deepwater Horizon would cost up to $700 million. BP has said its costs associated with containing the spill are running at $6 million a day. The company said it will spend $100 million to drill the relief well, which it does not expect to be operating for up to 3 months. The Coast Guard has not yet reported its expenses.