It's been a year since the Keystone pipeline leaked about 407,000 gallons of oil in northeastern South Dakota, and while the damage has been mitigated, a final federal investigation report has yet to be released.
The rural Marshall County site has been cleaned up, but there's still no final investigation report from the federal Pipeline and Hazardous Materials Safety Administration, the Aberdeen News reported.
The Nov. 28, 2017, Keystone leak is the seventh-largest onshore oil or petroleum product spill since 2010. The pipeline is owned by TransCanada and carries crude oil more than 2,600 miles from eastern Alberta to Oklahoma and Illinois.
"While we firmly believe no incident is acceptable and deeply regret that this occurred, our teams executed our emergency response and cleanup procedures effectively, in close cooperation with regulatory agencies, community members and landowners," said Robynn Tysver, a spokeswoman for TransCanada.
The pipeline was likely damaged during installation during 2008, according to a July report from the National Transportation Safety Board, which is separate from the Pipeline and Hazardous Materials Safety Administration's report. The damage may have occurred when a vehicle drove over the pipe, causing it to weaken overtime.
The pipeline has had 14 leaks, most of which were minor, since it was commissioned in 2010, according to a federal spill database. TransCanada has worked to improve the pipeline's conditions, including unearthing a section of the pipeline about 15 miles north of the rupture site to perform maintenance.
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