Crews and equipment were being positioned Monday to begin cleaning up a spill on Alaska's North Slope that fouled an area of snow-covered tundra estimated to be about a quarter-acre in size.
A worker at the BP-operated Lisburne oil field noticed the spill from an 18-inch pipeline early Sunday. Oil cleanup crews rushed to the leaking pipeline at 3 a.m.
BP spokesman Steve Rinehart said the leak is in a flow line that carries a mixture of oil and water to a processing center. He said it was not clear how much oil leaked onto the tundra, but that the pipe was leaking at a "very, very slow" rate.
Rinehart said any impacts on the flow of oil from the North Slope were minor.
The pipe, which is about 5 feet off the ground, was not in operation when the leak was discovered. The oil and water mix leaking from the pipe is congealing and freezing in a cone-shaped pile, he said.
The Alaska Department of Environmental Conservation estimates the spill area at about a quarter-acre. The estimate includes an area that was "misted" with oil.
The cleanup cannot begin until an official cleanup plan has been approved, Rinehart said Monday afternoon. He did not know when that would be, but said BP, the Alaska Department of Environmental Conservation and the federal Environmental Protection Agency were working to get one in place as soon as possible.
"We are anxious to start cleaning up as soon as we have an approved plan," Rinehart said.
In the meantime, crews cleaned off a gravel road that runs along the pipeline so cleanup crews and equipment could be positioned at the spill site.
"All sides are working this thing diligently," Rinehart said.
At least once a day, there is a visual inspection of the pipelines, Rinehart said. The worker discovered the leak during one of those inspections, he said.
The cleanup of the site was waiting for the pipeline to be depressurized so crews could safely work on the problem, said DEC spokesman Tim Hoffman. The process was complicated by the possibility of one or more ice blockages in the line that could be affecting pressure, he said.
Without getting a closer look, it was impossible to know if the leak was coming from a hole in the pipe, a crack or perhaps seeping from a weld, Hoffman said.
"Nobody has been close enough to determine what caused it yet," he said.
The oil coming from the pipe was very thick. It appeared to have nearly stopped by Monday afternoon, Hoffman said.
The Lisburne oil field, which went online in late 1986, is part of greater Prudhoe Bay and lies just north of the Prudhoe Bay oil field, North America's largest .
An average of about 687,150 barrels of oil flows from North Slope fields through the trans-Alaska pipeline daily to tankers in Valdez for delivery to the West Coast.