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.