Bemidji August 2007

Focus on Environmental Geology

The first day of the workshop trip is heading west, seeing the end of the "lakes region" with the glacial hills, lakes and woods and the start of the bottom of Glacial Lake Aggasiz. The map above outlines our approximate travel route.

The first stop is at the Pinewood crude oil spill site.⁽¹⁾ On August 10, 1979, approximately 10,700 barrels of crude oil were spilled when a crude oil pipeline burst about 10 miles northwest of Bemidji. The pipeline operators recovered most of the oil but an estimated 2500 barrels was left, most of it infiltrated through the sandy soil to accumulate in the water table. The site of the spill is in an unpopulated area owned by the State of Minnesota so the so the U. S. Geological Survey developed the site into a research area.

The research into the natural progression at the site continued from 1982 to 1999. In 1999 the pipeline company bean a remediation effort that changed the groundwater flow to prevent the crude oil from reaching the lake to the east. The research continues and is updated at http://toxics.usgs.gov/sites/bemidji_page.html

The aerial images from MapQuest show features not readily visible from the ground. This is an exciting new feature not possible even just a few years ago.

The shack at right houses equipment that continues to monitor the effects of the spill. The photos below show the path of the underground pipeline as it brings crude oil for processing into the fuel oil that we use to heat our homes and gasoline that we use in our cars. Water was pumped out of a well (to create a depression in the water table away from the lake) and them "skimmed" to remove the oil. This proceedure didn't work very well and has been discontinued. The current technique of letting bactera work on the crude oil has kept the oil out of the lake. Measurements indicate that the oil has made it only 1/5 of the way to the lake even though water that once carried the oil has made it to the lake.

The sand you see is the natural "soil" in this area, left over from the advance of the glaciers about 10,000 years ago. Even 28 years after the spill the odor of the crude oil remains in the air.

The area to the west of the pipeline has been populated with white pine trees. The area to the east where there is a small lake is covered with monitoring wells that you can see in the lowere photos.

Automated equipment continues to send data to scientists constantly by phone line and samples are collected on a regular basis. The advance of the crude oil seems to have been halted by a combination of efforts by the pipeline owners and natural action of bacteria. There is no evidence that the crude oil has made it to the nearby lake.

A bonus of the research is that geologists have been able to better determine how water moves from rainfall into the water table.

1. Minnesota Minerals Education Workshop Fieldtrip Guidebook, by Dr. Tim Kroeger, Professor of Geology, Bemidji State University