Updated at 6:50 p.m.
Two days after a crude oil leak in St. Charles County was first reported, officials announced Friday that the Keystone pipeline was the likely source of the spill.
Both the Keystone and the parallel Platte pipeline were stopped late Wednesday as crews worked to discover which of the two had caused the release of at least 43 barrels, or 1,800 gallons, of oil.
By late Friday, Enbridge Inc. said that it had begun a restart plan for its Platte pipeline and that the line could be fully operational by Saturday.
The status of the Keystone line, which is owned by TransCanada Corp., was less certain.
“At this time, there is no estimated timeline to return to service,” said Matthew John, a TransCanada spokesman.
Keystone is a major artery for Canadian crude to U.S. refiners, typically channeling around 600,000 barrels of oil per day toward its eastern terminus in Patoka, Ill.
On Friday, about 75 workers were on-site to excavate the pipelines and pinpoint the source of the leak.
Though it was not fully uncovered, Brad Harris, chief of the environmental emergency response section for the Missouri Department of Natural Resources, said that the pipeline companies found enough evidence for TransCanada to take responsibility for the spill.
The company said that “specialists continue to affirm there is no threat to public safety or the environment.”
DNR echoed that it “has met with all affected landowners and at this time there are no concerns,” the agency said.
On Thursday it reported that the spill was contained to a surface area of about 4,000 square feet less than half of a mile south of the Mississippi River, and that any area wells would be surveyed and checked for contamination.
The spill and shutdown of portions of the Platte and Keystone pipelines raised fresh concerns about pipeline safety, and about the already constricted flow of Canadian oil to U.S. refineries.
Canadian pipelines are congested because of expanding production in recent years, forcing the Alberta provincial government to order production cuts starting last month. Canadian heavy oil has attracted greater demand after U.S. sanctions against Venezuela’s state oil company.
“The exact quantity of oil released can’t be determined until excavation is complete,” an agency update said, adding that “it is unclear how long the release lasted, but a follow-up investigation should be able to estimate its duration.”
Some concerns about the pipeline in the area have simmered for about a decade.
In 2010, TransCanada was forced to excavate some parts of the Keystone project because of potentially defective steel used in its construction. As the Post-Dispatch reported that year, even more swaths of the pipeline may have required excavation if government requirements for pipe strength had not been relaxed in 2009.
The Associated Press and Reuters contributed to this report.
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Bryce Gray
Reporter covering energy and the environment for the St. Louis Post-Dispatch.
