42,000 Gallon per day leaking into Gulf

As efforts failed Tuesday to contain the flow of tens of thousands of gallons of oil leaking from an exploded well deep in the Gulf of Mexico, emergency response teams are considering a controlled burn-off of the oil on the water's surface as early as today.

Tuesday night, the expanding oil slick was about 20 miles off the coast of Louisiana and stretched 100 miles wide by 45 miles long at its greatest expanse.Workers were girding to protect environmentally sensitive areas nearby in the Mississippi River delta that are home to migratory birds and a nursery for nearly a quarter of the seafood production in the continental United States.

"It is the closest it's been to shore throughout this response, and we're paying attention to that, very careful attention to that," said U.S. Coast Guard Rear Adm. Mary Landry. She added that if the spill isn't contained, it has the potential to become "one of the most significant oil spills in U.S. history."

Watch video of the spill

Crews with BP Exploration and Production are using as many as eight remote-controlled submersible vehicles in an effort to trigger a shutoff valve, called a blowout preventer, that could stop the estimated 42,000 gallons of oil a day leaking from a well more than 5,000 feet below the surface of the Gulf. Those efforts came up short again Tuesday, and other alternatives to permanently containing the spill could be three months away.

NASA imageA closeup of the oil spill in the Gulf of Mexico, still 20 miles from the Louisiana coastline.

BP officials do not know why the blowout preventer did not engage after an explosion on the Deepwater Horizon drilling rig last week, in which 11 workers are still missing and presumed dead. A BP official estimated that the company is spending more than $6 million a day in efforts to contain the oil spill.An official with the Minerals Management Service, which regulates offshore drilling and mineral resources, said that the failure of the blowout device would certainly be the focus of an accident investigation. In the event the blowout preventer cannot be activated, BP is also working to build a series of containment domes that would be placed underwater to corral the oil and allow it to be pumped to storage tanks on nearby ships.

The company is also about to begin drilling separate "relief wells" that would intersect the leaking well and allow the company to pump a heavy drilling fluid into the well to counteract the flow. Eventually it would be plugged with concrete. That process could take up to three months, and the containment domes will not be finished for at least two to four weeks.

Meanwhile, the rhetoric ramped up Tuesday in Washington, with energy committees in both the House and Senate pledging to investigate the cause of the explosion.

First hearing on Capitol Hill is May 6

At the request of Sen. Mary Landrieu, D-La., the Senate Energy and Natural Resources Committee will hold a hearing May 6 on the rig disaster. A separate investigation by the Departments of Interior and Homeland Security has been under way since last week, and the heads of both agencies said Tuesday they will have the power to issue subpoenas and hold hearings to figure out what triggered the explosion and subsequent oil spill.

"This major accident and its potential implications to the environment need to be better understood," Landrieu said. "The public deserves a full hearing on this matter to ensure that everything that can be done is being done to maximize worker safety and minimize environmental damage."

Another environmental group, the Sierra Club, Tuesday joined Friends of the Earth in saying that the accident is another reason for Congress to reject the Obama administration's call for new drilling in the Eastern Gulf and the Atlantic Coast.

"This terrible tragedy is a sad reminder that oil is dirty, dangerous and deadly," said Athan Manuel, director of the Sierra Club's Lands Protection Program. "Instead of risking our lives, our coasts, our clean air, and our security by perpetuating our addiction to oil, it's time to build a clean energy economic that means more jobs, less pollution and real energy independence."

Chris John, a former Louisiana Democratic congressman who now is president of the Louisiana Mid-Continent Oil and Gas Association, said the accident is tragic, but that the oil and gas industry generally has a very good record of safety and avoiding major oil spills.