Pipeline Safety: Information on Keystone Accidents and DOT Oversight, Report to Congressional Requesters [open pdf - 2MB]
From the Highlights: "Since it began operating in 2010, Keystone has transported over 3 billion barrels of crude oil from Canada to refineries in Illinois, Oklahoma, and Texas, according to its operator, TC [TransCanada] Energy. Prior to construction, TC Energy requested and obtained a special permit from PHMSA [Pipeline and Hazardous Materials Safety Administration] to operate certain portions of the pipeline at a higher stress level than is allowed under PHMSA's regulations. Since TC Energy was the first and remains the only hazardous liquid pipeline operator to request a waiver of this particular regulation, the Keystone special permit is unique. GAO [Government Accountability Office] was asked to review PHMSA's oversight of the Keystone Pipeline. This report discusses: (1) PHMSA's actions to approve the Keystone special permit and allow the pipeline to operate at a higher stress level, (2) how Keystone accidents compare to accidents on all U.S. crude oil pipelines since 2010, and (3) PHMSA's actions in response to Keystone safety issues."
Government Accountability Office: https://www.gao.gov/