Engineers and technicians working for the energy company BP are performing tests on the damaged oil well that could clear the way for what is called a "static kill" as early as Tuesday. Government officials also favor a plan that would involve a "bottom kill" - using a relief well being drilled beneath the Gulf of Mexico, so that the damaged well is sealed permanently.
Former U.S. Coast Guard Admiral Thad Allen, the government official in charge of the Gulf oil spill cleanup, says crews are moving very cautiously in preparing for the static kill, which involves sealing the damaged well with mud and cement once the pressure inside is stable.
Allen told reporters on Monday that it might take technicians a few days to determine how stable the well is and how safe it would be to start pumping in mud to plug it.
"If we start pumping mud in and, all of a sudden the pressure does not go down and we hit just a flat line and the pressure stays there, that means it is going somewhere; that would be of concern," said Thad Allen. "So what you want is for the pressure to slowly decrease until it becomes zero in the well - that means the amount of mud is equal to the pressure being pushed up. But if it stops somewhere short of that, that means we may have a problem with the integrity of the casing of the well bore. So we really will not know until we do the final diagnostics."
In an earlier press briefing, BP officials seemed to indicate that this top kill would be sufficient and that it might not be necessary to do a bottom kill, by drilling a relief well to intersect with the well bore.
Allen, however, did not rule out the use of the relief well. He said the bottom kill plan is still in effect and that further tests need to be done to determine how it should proceed.
Meantime, the U.S. Environmental Protection Agency announced on Monday that a new study supports the use of dispersant chemicals to break up the oil slick caused by the leaking well. Some critics in Congress and in the environmental community have questioned the use of the chemicals and say excessive amounts were used.
But EPA Assistant Administrator for Research and Development Paul Anastas told reporters that studies show the dispersants are less harmful than the oil they attack.
"We see that dispersants are working to keep oil off our precious shorelines and away from sensitive coastal ecosystems," said Paul Anastas. "We also see that dispersants are less toxic than the oil being released into the Gulf [of Mexico]. We see further that the dispersant-plus-oil mixtures have roughly the same toxicity as the oil itself."
Anastas said the dispersants were used in an area about 80 kilometers off the U.S. coast, well beyond the 4.8-kilometer limit established by the Environmental Protection Agency. He said the EPA will continue testing, but that there has been no evidence so far of harm done to coastal wildlife or ecological systems by the dispersants, while, he said, the negative effects of the spilled oil are all too evident.