For evidence against the transport of tar sands crude, environmentalists point to an event in May 2011, when 21,000 gallons of oil leaked in North Dakota. This was also due to a faulty valve. The State Department says the maximum amount of spillage in a worst-case-scenario of a Keystone Pipeline leak is 2.8 million gallons spread throughout a 1.7 mile area. TransCanada points out that this is significantly smaller than the amount that escaped during the Deepwater Horizon disaster.
A March 2013 spill of tar-sands bitumen in Mayflower, Arkansas put the Keystone XL pipeline back in the spotlight. An ExxonMobil pipeline carrying tar sands oil from Canada burst, sending more than 12,000 barrels of oil down residential streets and through people’s yards. The pipe was decades old. The spill was categorized as “major” by the Environemntal Protection Agency (EPA) and the cleanup is ongoing.
The pipeline is often compared to another one built by the Canadian energy company Enbridge, which also transports tar sands crude into the U.S. Enbridge, a competitor of Transcanada, “has actually been transporting these types of products [tar sands crude] since 1999 in our pipelines,” said Denise Hamsher, Enbridge’s head of planning. Despite her claim, Enbridge is not without heavy public scrutiny. In July 2010, one of Enbridge’s pipelines ruptured in southern Michigan. Thousands of gallons of oil sands crude flowed into Talmadge Creek, a tributary of the Kalamazoo River. The event caused the EPA to recommend to the State Department that pipelines carrying tar sands be regulated differently than pipelines that carry other types of oil.