European Pressphoto Agency

A study released by a University of Nebraska researcher says that TransCanada has presented American regulators with an “an unrealistically optimistic” portrayal of the consequences of a spill from its proposed Keystone XL pipeline.

The pipeline is an expansion of an existing pipeline that delivers synthetic crude from Canada’s oil sands to the United States. Several environmental groups are urging regulators and the State Department not to approve Keystone XL, arguing that oil sands are a particularly dirty energy source.

At a news conference on Monday hosted by the group Friends of the Earth, John S. Stansbury, a professor of environmental and water engineering at the University of Nebraska-Lincoln, said he anticipated that the pipeline would experience 91 spills producing leaks of more than 50 barrels of oil during its first 50 years of operation. TransCanada, by contrast, predicts only 11 spills of that size or larger, according to Dr. Stansbury’s analysis of its regulatory filings.

Dr. Stansbury also concluded that it would take 10 times longer to shut down the pipeline when a leak developed than TransCanada estimated, that the company’s systems for electronically sensing spills were not as reliable as it claimed and that a worst-case spill would release about six times more oil than the company anticipated.



“You would not have to expect the worst-case spill, but you would have to plan for it,” he said. He noted that even if a spill only reached TransCanada’s much lower estimates, “it would be a huge problem.”

Dr. Stansbury said he produced the report on his own to inform legislators and officials about potential problems related to a pipeline that would pass through his home state. The study has not been published by a scientific journal or undergone a formal peer review process.

In a statement, TransCanada rejected the report’s conclusion that it was playing down the potential severity of spills.

“We use risk-based assessments that are industry-leading methods to quantity failure frequency,” the company, based in Calgary, Alberta, said.

TransCanada also disputed Dr. Stansbury’s estimates about shutdown times. During two incidents in May, the company said, the existing Keystone pipeline was shut down within 10 minutes and no oil was released outside of pump stations.

The study mirrors the continuing debate about the properties of oil sands crude. Dr. Stansbury said in his report that the proposed pipeline would have more frequent spills in part because “the crude oil that will be transported through the Keystone XL pipeline will be more corrosive than the conventional crude oil transported in existing pipelines.”

While several environmentalists have also said that oil sands crude is more corrosive than conventional crude, TransCanada said a study that it commissioned showed that this was not the case.

“Why would we construct a $13 billion pipeline system only to put something in it to destroy it?” the company said.