NATIONAL NEWS (CNN) — A Royal Dutch Shell oil drilling barge that ran aground last week off southern Alaska is being towed with no sign that it's leaking fuel, an incident response team reported Monday.
As of 3 a.m. (7 a.m. ET), the rig had been towed about 19 miles from land on its way toward Kiliuda Bay, where authorities plan to more thoroughly assess its condition.
Salvage crews refloated the 266-foot-diameter Kulluk on Sunday night and began towing it a few hours later, according to the incident response team.
The rig ran aground off uninhabited Sitkalidak Island, about 200 miles south of Anchorage, after tug crews towing it had to cut it loose on December 31 during a storm that whipped up 24-foot waves. The U.S. Coast Guard had evacuated the rig the previous day amid a severe storm as it was being towed back to its winter home in Seattle.
The rig had been working in the Beaufort Sea, off Alaska's North Slope.
As much as 150,000 gallons of ultra low sulfur diesel and about 12,000 gallons of other petroleum products are on board the Kulluk, a double-hulled steel vessel with a helicopter landing pad and tower in the middle designed for drilling in Arctic waters.
Infrared cameras on a boat accompanying the rig as it was being towed detected no signs of leakage early Monday, according to the unified incident response command, which includes the Coast Guard, Alaska's state environmental conservation department, a drilling company and Kodiak Island officials.
Earlier assessments also indicated the rig was in good condition and posed no environmental hazard.
A Coast Guard cutter and two oil spill response ships are on standby should any spills occur, the incident response team said.
Shell's Arctic exploration plans caused widespread concern among environmentalists and were held up after BP's 2010 Deepwater Horizon disaster in the Gulf of Mexico.
Shell says it's working at far less depth and lower pressures than the BP well that erupted off Louisiana, killing 11 men aboard and unleashing an undersea gusher that took three months to cap.
The U.S. Geological Survey estimates more than 90 billion barrels of oil and nearly 1,700 trillion cubic feet of natural gas may be recoverable by drilling in the North Slope area.
CNN's Melissa Gray, Matt Smith, Dana Ford and Greg Botelho contributed to this report.