ConocoPhillips Alaska employees evacuated due to prolonged natural gas leak on the North Slope

ConocoPhillips evacuated employees this week at its Alpine oil development on the North Slope due to a natural gas leak, company officials said.

The leak was detected early Friday at the drill site CD1, 8 miles north of the village of Nuiqsut, ConocoPhillips said in a statement.

The company said it “relocated” some of its non-essential employees Monday afternoon “out of an abundance of caution,” including workers at the CD1 pad and its Alpine central processing facility and camp, the statement said. A ConocoPhillips spokesman would not say how many employees were affected, or where they were moved, adding that the company was working to provide additional information.

“There are no reports of injury or environmental impact to the tundra or wildlife,” the company’s statement said. “Air quality continues to be monitored and no natural gas has been detected outside of the CD1 pad.”

The gas leak happened below gravel, and its cause and scale are under investigation, Conoco said. The company said it is using natural gas detection monitors at the CD1 pad, and conducting infrared surveys from the air.

Alpine stayed operational as of Tuesday and continues to supply the village of Nuiqsut with the gas that residents and institutions use for heating.

The Alaska Oil and Gas Conservation Commission is monitoring the situation, said special assistant Grace Salazar.

“Based on its investigation to date, the commission is unaware of any threats to public safety,” Salazar said in an email.

Nuiqsut is already heavily impacted by oil development, and residents there reacted to news of the gas leak with concern. City officials are encouraging residents to be ready to evacuate if the need arises.

“We ask that the community be prepared in case the adverse events continue and gather their medications in an emergency go-bag,” said Mayor Rosemary Ahtuangaruak. “We are working out a plan for if we have to make that call.”

Some residents had already started leaving the village Monday “because they are worried about what could happen, and don’t want to be here if things get worse,” Ahtuangaruak added.

The city is initiating air sampling to assess local air quality, Ahtuangaruak said. She encouraged residents who have concerns about air quality to contact the Nuiqsut Utilities Cooperative, which provides the natural gas heat source to the village, to conduct air sampling around their house.

Some residents have reported smelling gas since Friday and have also complained of headaches. But officials with the North Slope Borough, which has been monitoring the situation, said the odor is not because of the leak — instead, it’s likely because of a quirk in the way Nuiqsut’s gas is being consumed.

Natural gas is odorless when it is in the ground, but utility managers typically add a compound called mercaptan so that leaks can be detected.

Nuiqsut’s biggest institutional gas consumers, like the school and power plant, temporarily switched to fueling with diesel during the leak, and it takes time to reduce the amount of mercaptan added to the village’s gas supply — so the gas that residential customers are currently burning has a larger mercaptan concentration, said Mitchak Gatten, an official with the borough’s risk management office.

Residents in Nuiqsut, where temperatures were around zero degrees Fahrenheit on Tuesday, have also expressed concerns about the continuing availability of gas to heat their homes in the event that ConocoPhillips has to shut down its pipeline.

But if that happens, Gatten said the oil company has pre-pressurized the line with enough gas to last for at least 10 days, and as long as three weeks.

The leak comes at a sensitive time for ConocoPhillips, which has faced opposition from environmental groups and some Indigenous North Slope residents to its major new Willow development just to the west of Nuiqsut. Activists were quick to share news of the leak, pointing out that a key public comment deadline on the Willow project is Wednesday.

Ahtuangaruak, who’s worked with environmental groups to oppose the Willow development, said Nuiqsut “is reacting to living through previous events,” such as a blowout 10 years ago at a drilling site run by Spanish oil company Repsol. During that event, Ahtuangaruak said, gas emissions lasted several days.

“Our village had to hunker down during that process, and it was weeks that community members had respiratory distress,” Ahtuangaruak said.

“We are still highly concerned, and we are on high alert and awaiting updates,” she said.