Even with Nebraska's decision in hand, TransCanada still must formally decide whether to build the line, which would send crude from Hardisty, Alberta, through Montana and South Dakota to Nebraska, where it will connect to pipelines leading to U.S. Gulf Coast refineries.
The spill risk analysis was conducted by global risk management company DNV GL.
The company says USA regulators have cleared its restart plans, which include restarting the pipeline at a reduced pressure before gradually increasing the volume of crude oil in the system.
Members of South Dakota's Public Utilities Commission told Reuters last week they could revoke TransCanada's operating permit if an initial probe of last week's spill shows it violated the terms of the license. Conditions include construction standards and environmental requirements. TransCanada's report to regulators, produced by an outside risk assessor, said that a spill should have occurred along the South Dakota section no a few times every 41 years.
"They testified that this is going to be a state-of-the-art pipeline", said one of the commissioners, Gary Hanson.
And in South Dakota, where the line has leaked twice, the estimate was for a "spill no a few times every 41 years".
TRP says it is seeking a "clarification" on the PSC's decision last week to approve an alternative route for the pipeline.