Keystone pipeline crack grew over 15 years: South Bow

A North Dakota oil spill was probably the result of a crack in the Keystone pipeline that grew over a 15-year period, a third-party investigation concluded.

A Calgary energy company says it has pinpointed the cause of a leak in the Keystone pipeline in North Dakota last spring.

South Bow said Friday the pipe likely developed a crack while being transported before the pipeline was built.

That crack grew over the 15 years the pipe was in service.

About 3,500 barrels, or 556,000 litres of oil spilled on farmland.

South Bow said in November that the costs related to the spill have totalled US$55 million and are largely expected to be recovered through insurance by early next year.

The investigation was done by a third-party contractor.

With files from The Canadian Press