Keystone pipeline raises concerns after third major spill in five years

It is also the case that previous estimates from earlier spills on the pipeline have turned out to be much larger than the initial estimates.

Most of the undamaged parts of the pipeline resumed operations last week, as cleanup efforts and an investigation into the cause of the spill continue. On Tuesday it was reported that TC Energy had submitted its plan to regulators for fully restarting it.

The spill was the largest onshore oil spill since at least 2013 and the largest spill in the Keystone pipeline system since it began operating in 2010.

The crude tar sands oil transported by the Keystone pipeline differs from conventional oil. It consists of a heavy oil called bitumen that is cut with a lighter gas called a diluent to facilitate transportation through pipes.

About 22 oil spills have occurred on the Keystone pipeline in the past 12 years, with two other large incidents. TC Energy has only paid $300,000 in fines for previous spills on the Keystone pipeline, even if the spills caused more than $111m in property damage.

A 2010 report from an environmental law center identified a pattern of production and use of substandard steel in new pipelines amid a pipeline construction boombetween 2007 and 2009. A manufacturer linked to the Keystone pipeline was included.

Blackburn argued the possibility of fines levied on pipeline corporations are included in the cost of doing business for these multibillion-dollar corporations, which often pass the costs on to customers if they are not already covered by insurance. He noted regulators can force pipeline corporations to conduct more frequent in-line inspections, such as imaging tools that can perform ultrasounds on pipelines to identify possible points of failure and remedy them before a spill occurs.