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Continued: In Bemidji, a research site reveals secrets of an oil spill

  • Article by: DAVID SHAFFER , Star Tribune
  • Last update: June 15, 2014 - 7:12 PM

Scientists also found that bugs are not as fond of eating Bemidji’s thick oil, so it could take years of natural attenuation before the last of it is gone.

Pumping out the Bemidji oil is not considered an option. In 1999, or 20 years after the spill, Enbridge made a second try at the request of state regulators. Another 30,000 gallons of oil was suctioned out through wells over four years.

Unfortunately, water came out with the oil, and had to be injected back into the ground. That spread subsurface pollution in what researchers call the “remediation plume.” The good news is that bacteria are eating that plume too, according to a recent USGS study.

It’s one of about 270 research papers about the Bemidji site that have appeared in journals, from such prestigious ones as Nature and Science, to the lesser-known, aptly named “Environmental Forensics.”

Visit with a drill rig

Scientists rarely need to visit the site. Each year, a midsummer sampling event draws about 35 to 40 researchers. Most of the scientific work is done elsewhere, at institutions ranging from such East Coast universities as Rutgers in New Jersey and Syracuse in New York, to the University of British Columbia and the Juárez Autonomous University of Tabasco in Mexico.

Enbridge has kicked in about $600,000 in recent years to keep the research going. USGS puts in $180,000 a year, and jointly administers the site with Enbridge, Beltrami County, which owns the land, and the Minnesota Pollution Control Agency, which regulates the cleanup.

For new phases of research, Trost and two other USGS employees spent a week at the site in May. They sank two wells with the rusty drilling rig, and installed electronic moisture and vapor sensors.

Trost, who started working with the USGS as a student in 2006, is among the new generation of scientists now taking over from early spill researchers who have retired. He graduated from Augsburg College in Minneapolis and went on to earn a master’s degree in water resource science from the University of Minnesota in 2010.

Trost said one of his interests is a simple method to capture and measure gases released by microbes as they degrade oil. Measuring the gas at the surface reveals how fast oil is degrading below ground.

The technology is being used by energy giant Chevron and others to monitor underground oil degradation, API’s Bauman said. It also has turned out to be surprisingly useful in monitoring the success of ethanol spill cleanups. “A lot of unique sampling methods have been developed here and are starting to get noticed,” Trost said.

‘It blew oil like a geyser’

The rupture happened Aug. 20, 1979, on a 34-inch diameter pipeline carrying light crude oil from Canada. It is one of five Enbridge lines on a corridor across northern Minnesota carrying oil to a terminal and other pipelines in Superior, Wis.

On the morning of the rupture, the telephone rang at the home of Willis Mattison, who was then the regional director of the state Pollution Control Agency. He got to the site after daybreak. Cleanup crews already were at work.

“Everything was black and oily,” recalled Mattison, who retired in 2001.

The 450,000-gallon release is the seventh largest crude oil pipeline rupture in Minnesota. “It blew oil like a geyser into the air,” Mattison said. Wind splattered the oil over an area the size of a football field. Oil flowed into a wetland pond and percolated underground.

“The first thing they wanted to do was set it on fire,” Mattison said during his first visit to the site in more than 30 years. “We didn’t allow that. We told them to get down and start skimming and pumping.”

The most visible sign of the accident today is a large area of bare, eroded soil where little grows. Scientists are still studying why, after nearly 35 years, the oil-tainted soil still repels water, keeping moisture from plant roots. One theory: Oil-eating bacteria in topsoil don’t like Minnesota winters.

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  • At the site of 1979 spill near Bemidji, scientists have dotted the landscape with bore holes to study of the lingering underground pollution. Here, crews bore 27 feet below the surface to survey the groundwater for oil from the 1979 spill.

  • A rust-coated drilling rig, which dates to 1956, has bored dozens of test wells at the site of a 1979 spill near Bemidji, Minn. It has helped scientists produce research discoveries, including some that have influenced U.S. pollution cleanup policy.

  • USGS hydrologist Jared Trost stood among the many bore holes scientists use to study the movement and breakdown of crude oil.

  • What they found underground

    What scientists have found underground

    Scientists have published hundreds of articles in scientific journals using data collected at the Bemidji oil spill site. Here are the key discoveries over three decades.

    • Underground bacteria feed on oil and degrade it even in the absence of oxygen. Iron in the soil helps this process.

    • Bacteria eat petroleum fast enough to keep a subsurface plume of contamination from spreading. But microbes speedily devour only some petroleum compounds such as toluene, a toxic solvent.

    • If oil seeps into a water table, it can float there for decades.

    • Trying to suction oil from the water table via wells can produce large quantities of oil-tainted water, leaving things no better.

    • Crude oil compounds in a wetland got chewed up quickly by the rich microbe life.

    • When bacteria eat crude oil, they emit a gas that converts to carbon dioxide as it works though the soil. Gas-measuring devices on the surface can reveal the pace of the breakdown of subsurface oil.

    • Bugs that chew up buried crude oil sometimes free up arsenic, a toxic heavy metal. Scientists are studying whether other minerals react with arsenic to hold it in place.

    • Studying the genetic fingerprint of bacteria shows which strains work hardest at degrading petroleum.

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