At an old Minnesota oil spill site, scientists discover oil-eating microbes

Along a narrow road down an abandoned railroad grade about 20 miles northwest of Bemidji, a world-class outdoor laboratory lies among the pine trees.

In part, it marks the spot where on Aug. 20, 1979, a Lakehead Company pipeline seam split, spewing about 440,000 gallons of crude oil. It was one of the largest pipeline spills in Minnesota.

Today, the site is one of the most-studied crude oil spills in the world, and after three decades of research, it still produces important findings.

Scientists here discovered that bacteria that break down oil are everywhere, ready to go to work. Even in the northern Minnesota woods there are microbes that eat carbon and break down oil. The population of those bugs explodes when there's oil in the ground.

'Whoa, let's have a party'

"These microbes are there in very small quantities until 'whoa, let's have a party, we have food, we have carbon to eat,'" said Jared Trost, a hydrologist with the U.S. Geological Survey who helps manage the site.

Today the site attracts scientists from around the world. They come to collect data from an array of sensors that sample, soil, water and air.

Near the place where the oil spilled, a well-drilling rig is parked, and dozens of pipes sprout from the ground, marking test wells. All of the equipment is helping to track oil underground.

"Thirty-five years ago in August, this would have looked a little more black," Trost said.

Five pipelines now run through the area, carrying about 15 percent of U.S. crude oil imports. One pipeline carries oil north to Canada. The pipelines are now owned by Canadian Energy company Enbridge Inc., which provides financial support for the research site.

Enbridge provided $450,000 to help start the Pinewood research site and an additional $150,000 to help fund site operations.

Research funds come from the U.S. Geological Survey, from academic researchers and other sources. Other partners include Beltrami County, which owns land where research is conducted, and the Minnesota Pollution Control Agency.

Little visibile evidence remains

Much of the site bears no visible evidence of the spill. A wetland that was covered in several inches of oil now looks no different than other wetlands in the area.

But just up a hill, there's a large area with only a few scattered plants. It's still mostly bare dirt 35 years after the spill. The soil looks wet from the light rain falling, but anyone who scratches the surface will see that it's dry as a desert underneath.

"The reason being, that there's oil residue coating the sand grains," Trost said "And oil and water don't mix, and so water can't get through."

Researchers are just beginning to study these hydrophobic soils.

Much of the research done here since 1983 is underground, because that's where the oil is — in the soil and on top of the groundwater aquifer.

"Right where we stand we are about 28 feet above water, actually above oil — we're standing above oil here," Trost said. "There's about two feet of oil floating on the water table."

Today, the MPCA would not allow so much oil to be left behind.

Lakehead was responsible for the initial cleanup, and Enbridge did additional cleanup in the early 2000s, pumping groundwater from the site in an effort to remove oil. Enbridge is still responsible for any future cleanup needed at the site.

About 10 years ago, the MPCA proposed a plan to make Enbridge do a major cleanup at the site. Researchers rose up in opposition, presenting the agency with a choice, said Stephen Lee, an emergency response manager for the MPCA.

"Continue this world-class research that will benefit cleanups for generations to come or have Enbridge Pipeline dig one heck of a hole and dig that all out and fill it up with sand," he said. "And we chose to pursue the research."

Lee said the oil underground doesn't threaten drinking water supplies, because it is in an isolated area — and the pollution isn't spreading. In fact that's one of the things researchers learned in the past three decades. The oil didn't travel as far underground as expected.

USGS employees are testing a new method for installing moisture sensors underground.

They're preparing for the busy summer season when researchers collect data.

Much of the research now is shifting toward techniques to track underground oil without drilling dozens of intrusive, expensive wells, Trost said.

Scientists also are working to learn more about the microbes that like to eat oil. That research could help improve future oil cleanup.

There's still more to learn about the fate of the oil underground, USGS lead scientist Barbara Bekins said.

Researchers closely track the oil and dangerous chemicals like benzene that are released from the oil. But Bekins said there are worrisome unknown pollutants still to be studied.

"There's a large plume that's coming from the source at Bemidji," she said. "We only characterize it as dissolved organic carbon. We don't know the properties of the compounds in that plume. We'd like to know if they're toxic."

Bekins said the site likely will continue to yield scientific advances — as long as funding remains available to continue the research.