Environmental officers with the state of Alaska are investigating an oil spill at Prudhoe Bay, after an unknown quantity of natural gas, crude oil and water escaped from a flow line operated by BP Exploration Alaska on Monday, spraying 27 acres of snow-covered tundra with an oily mist.
The release from the line at H Pad, Well 8 in Western Prudhoe Bay began at 2:30 p.m. on Monday, but stopped in two hours after the line was isolated and depressurized, according to a statement from the Department of Environmental Conservation.
Such a large area of snow was covered because the leak occurred in the pipe's 12 o'clock position, on top, and the pressurized gas sprayed crude oil and water into a strong wind, said Ashley Adamczak, a spokesperson with DEC.
"The pressurized gas forced fluid to go up and hit a 30 mph wind, and that is what caused such a long release," said Adamczak.
The damage is a little more than a mile from the 2006 leak of a transit line that ultimately became the largest recorded spill on the North Slope. That spill lasted five days and discharged 200,000 gallons over two acres. BP ultimately pled guilty to negligent discharge after failing to address corrosion.
In response to that event, the company spent $500 million and upgraded 16 miles of transit pipeline headed to a processing facility -- called Gathering Center 2 -- where oil, gas and water are separated, said Dawn Patience, a BP spokesperson.
This latest leak occurred in six-inch-diameter pipe leaving a wellhead. Such flow lines or well lines connect to a manifold and eventually a transit line that's headed to a processing facility, Patience said.
The 2006 event is completely unrelated to the current release, said Adamczak.
As for the cleanup, the hope is to get the oil and water removed before the snow and ice melts, and before migratory birds arrive in perhaps a couple of weeks, Adamczak said.
No wildlife has been observed at the site, the agency reported.
To determine the amount of fluid spilled, the agency plans to collect oiled snow and ice. "We'll go into the field and do assessments in different areas to see the depths and volume of the product in what we consider to be representative areas and come up with an estimate," Adamczak said.
BP, which operates Prudhoe Bay on behalf of partners Exxon Mobil and ConocoPhillips, is the responsible party for the cleanup. The company and the Environmental Protection Agency, the DEC and the North Slope Borough have established a unified command to oversee the response.
In addition to DEC's investigation into the cause of the release, BP is also investigating the cause of the spill, said Adamczak.
"I'm sure other agencies will look into it as well," she said.
A photo of the damaged pipe on the agency's website shows what appears to be a large rupture. Adamczak said she did not know the size of the hole, but that information would likely be available on Wednesday as the agency releases more information.
After the spill, on Monday evening, cleanup contractor Alaska Clean Seas worked "to establish site control, set up staging and decontamination areas, clear affected snow to accommodate response traffic, and delineate the spill area," according to the release. BP and Alaska Clean Seas are working on a plan to deter wildlife from entering the spill area, the DEC said.
A BP pad observer spotted the release during a routine inspection, according to the DEC statement. The first notification of the event came from gas alarms, Patience said.
"The leak occurred as a producing well was being returned to service," Patience said.
"People responded they should, no one was injured and they took all precautions because of the gas alarms," Patience said.