Alaska regulators are investigating crude oil discovered along a buried section of the Trans-Alaska pipeline north of Fairbanks.
Alyeska Pipeline Service Co. recovered 10 gallons (39 liters) of crude oil discovered on Sunday following an excavation at the site south of Atigun Pass, the Anchorage Daily news reported.
Crews inspecting a mainline valve discovered the oil in soil and an excavation at the site is continuing, said Alyeska Pipeline spokeswoman.
"Engineering and field personnel are assessing the situation and developing plans to safely excavate the valve and to determine the cause of crude oil in the excavated area," the spokeswoman said on Tuesday.
An environmental program specialist with the state Department of Environmental Conservation said that the oil could have been overlooked from the 2013 oil release that occurred at the same site. 21 gallons (79 liters) were linked to the soil movement that occurs as tundra freezes and thaws, she added.
Although finding some oil traces were probable, the amount found by the inspection crew was more than expected.
"We're working through Alyeska to develop a cleanup plan, and to figure out if this is contamination left from the 2013 release or whether it is indicative of a new issue at the valve," the environmental program specialist concluded.