Robots using giant hydraulic shears finished cutting away the pipe atop a BP well gushing oil into the Gulf of Mexico, clearing the way for a cap to be placed over the well on Thursday in an effort to contain the 45-day-old spill.
Cutting away the riser pipe is "a significant step forward," Coast Guard Adm. Thad Allen, the national incident commander, said at a briefing Thursday morning. "The challenge now is to seal that containment cap over it."
Allen said the shears used in the cutting did not give the clean edges that officials had hoped for, which could make it more difficult to fit the cap tightly over the pipe. The shears were used after a diamond-edged saw got stuck Wednesday while cutting through the pipe.
"This is an irregular cut. It will be a bit more challenging" to tightly seal the cap over the ragged-edged opening through which oil is gushing, Allen said.
The cap was already suspended over the area and would be lowered into place within hours, he said.
The cap is intended to contain, not stop the flow of oil, but the tighter the cap, the more oil will be contained.
The spill is not expected to be fully controlled until August at the earliest, after two relief wells are completed.
In the meantime, the oil continues to spread, with the upper edge of the spill approaching Florida and 37% of gulf waters closed to fishing.
Hurricane season, which began June 1, poses a major problem to workers trying to finish the relief wells, something Allen acknowledged was a concern. He said officials had to face the possibility that a major storm would force a halt to work on the relief wells.