Though Exxon Mobil initially insisted that the pipeline that ruptured and spilled into Montana’s Yellowstone River this month carried only low sulfur crude from Wyoming, the company has now acknowledged that the pipeline is used to transport tar sands crude from Alberta.
Oil from the Canadian tar sands is produced by melting asphalt-like deposits and must be diluted with lightweight and volatile chemicals in order to flow through pipelines. Tar sands oil is known to be more corrosive than other types of crude and it contains more heavy metals.
More than a week after Exxon told reporters that the pipeline that spilled 42,000 gallons into the Yellowstone River on July 1 carried only sweet crude the company admitted that the line routinely transports crude from the tar sands region. Exxon maintains that the oil that spilled was not of the more heavily polluting tar sands variety.
“Oil from Canada was in the line, but not that area that was affected by the breach. The oil that spilled out, that oil came from Wyoming,” Exxon spokeswoman Karen Matusic told Reuters.
The U.S. State Dept. is in the process of considering a permit for a massive new pipeline that would move 700,000 gallons of Canadian tar sands crude to U.S. refineries each day, and oil companies are eager to minimize scrutiny of the special environmental dangers involved with transporting this type of crude.
When an Enbridge pipeline spilled more than 800,000 gallons of Canadian crude into the Kalamazoo River system last summer, company CEO Pat Daniels initially denied but later admitted that the oil was tar sands crude.
That heavy oil has sunk to the bottom of the river, which remains closed to the public due as a health hazard.
In statements urging more study of the proposed Keystone XL pipeline the U.S. EPA has warned that not enough is known about how tar sands oil affects the environment when it spills.
Last week a University of Nebraska risk assessment expert warned that even a small, undetected leak from the Keystone XL pipeline in the Nebraska Sand hills could pollute almost 5 billion gallons of groundwater with benzene at concentrations exceeding safe drinking water levels.