FILE - In this Nov. 3, 2015 file photo, the Keystone Steele City pumping station, into which the planned Keystone XL pipeline is to connect to, is seen in Steele City, Neb. The company that wants to build the Keystone XL pipeline is asking a Montana judge to change his order blocking the project to allow pre-construction work to continue, such as purchasing materials and finalizing contracts. Attorneys for the company will argue in a Wed. Nov.28, 2018, telephone conference that U.S. District Judge Brian Morris should clarify or amend his ruling to say the injunction does not apply to activities such as finalizing contracts, purchasing materials, conducting land surveys and discussing federal permits. (AP Photo/Nati Harnik, File)

Keystone spill caused by crack that progressed over time: TC Energy

TC Energy Corp. says a third-party investigation into an oil spill from the company’s Keystone pipeline in December has concluded the incident was caused by a crack in a weld that occurred at the time of the pipeline’s construction.

The Calgary-based company says the affected pipe segment was subjected during construction to “inadvertent bending stresses,” initiating a small crack that progressed over time to pipe failure after a decade of operations.

TC Energy says the findings are consistent with the conclusions from an earlier metallurgical analysis, the results of which the company released in February.

TC Energy was ordered to commission a third-party investigation by a U.S. regulator after the Keystone pipeline leaked about 13,000 barrels of oil spill into in Washington County, Kansas in December.

The Canadian company is still on site cleaning up the mess. It says it has recovered 98 per cent of the spilled oil and remediated 90 per cent of the creek’s shoreline.

Last month, the U.S. Pipeline and Hazardous Materials Administration expressed concern over the risk of additional spills from Keystone, and ordered TC Energy to operate the pipeline at a reduced pressure until it receives written permission from the regulator.