Pipeline Ruptures in Prudhoe Bay Alaska

BP Exploration (Alaska) Inc. employees and other emergency response workers have been working 24 hours a day to contain and clean up an oil spill that was discovered on Tuesday. The spill was found at a caribou crossing, but exactly where the leak began on the underground pipeline is unclear. The spill appears to have affected about one acre of land. On Tuesday, BP Exploration (Alaska) reported to state regulators that the initial spill was estimated at 500 gallons. On Wednesday, the Department of Environmental Conservation upgraded the figure to 2,000 gallons, including 500 gallons of crude oil and 1,500 gallons of gas and "produced water," which is water that flows out of wells mixed with oil. The ruptured pipe carried oil from production pads to a processing plant called Gathering Center 1, where oil, water and gas are separated. The leak occurred about half a mile west of the plant, where the buried pipeline passed under the Spine Road.

Relatively speaking, it's not a particularly large spill, said Ed Meggert, on-scene coordinator for the DEC's northern spill response office. BP told the department the materials carried in the pipe were more than 75 percent water, Meggert said, meaning the leak released roughly 1,500 to 2,000 gallons of saltwater over the spill area. Saltwater can be as toxic on dry tundra as diesel fuel, according to the DEC. Still, the water is being diluted by snow and the department suspects it won't penetrate the frozen ground.

Oil wells producing 8,000 to 10,000 barrels of crude oil a day remained shut down because of the pipeline rupture. Overall, Prudhoe and other North Slope fields produce a total of about 1 million barrels a day. BP was not sure how long it would be before production could be restarted.

A BP spokesman confirmed that another spill occurred at Prudhoe on Sunday at nearby Gathering Center 2. That spill involved about 1,700 gallons of produced water, with all but about half a gallon contained inside the building. The spokesman said that spill was the result of corrosion.