BILLINGS, Mont. (AP) - Following a string of explosive accidents, federal officials said Thursday that crude oil being shipped by rail from the Northern Plains across the U.S. and Canada may be more flammable than traditional forms of oil.
A safety alert issued by the U.S. Department of Transportation warns the public, emergency responders and shippers about the potential high volatility of crude from the Bakken oil shale patch. The massive oil reserve is fueling the surging industry in eastern Montana and western North Dakota, which is now the nation's second-largest oil producer.
The warning comes after a massive explosion caused by an oil train derailment on Monday near Casselton, N.D. No one was hurt, but worries about toxic fumes prompted the evacuation of hundreds of residents from the small eastern North Dakota town.
The oil boom in the Bakken has reduced the nation's reliance on imported oil and brought thousands of jobs to the region. But as companies have increasingly relied on trains to get that oil to lucrative coastal markets, public safety in communities bisected by rail lines has become a major concern.
In July, 47 people were killed in Lac-Megantic, Quebec, when a train carrying Bakken crude derailed. Another oil train derailed and exploded in Alabama in November, causing no deaths but releasing an estimated 749,000 gallons of oil from 26 tanker cars.
The amount of oil moving by rail in the U.S. has spiked since 2009, from just more than 10,000 tanker cars to a projected 400,000 cars in 2013.
Thursday's safety alert resulted in part from results of preliminary tests on Bakken oil to determine just how dangerous it is, said Jeannie Shiffer with the Department of Transportation's Pipeline and Hazardous Material Safety Administration.
Shiffer said knowing the volatility of the oil is crucial so that it can be properly handled during shipping.
"The material must be properly classified at the beginning of the process. That determines everything," she said.
The issue of volatility is of particular importance for fire fighters and other emergency responders who have to deal with accidents like the one in Casselton, said Fred Millar, a rail safety consultant in Virginia.
While it may appear obvious that crude oil is dangerous, that message has not been adequately communicated to the hundreds of counties and cities across the U.S. that have seen a surge in crude oil trains, Millar said. He added that railroads should also consider routing the Bakken oil trains around highly populated areas.
After the Lac-Megantic crash, federal officials issued an advisory for companies to properly classify their crude oil according to a scale that ranks hazardous materials as a great danger, medium danger or minor danger.
Thursday's announcement goes a step farther, declaring that the Bakken's light, sweet crude oil - extracted from shale formations through the drilling process known as hydraulic fracturing, or "fracking" - may be different from traditional heavy crudes because it is prone to ignite at a lower temperature.
The volatility of crude varies from one oil field to the next and is driven largely by how heavy it is, said Kenneth Medlock, senior director at the Center for Energy Studies at Rice University in Houston. Lighter crudes, which contain more natural gas, have a much lower "flash point" - the temperature at which vapors given off by the oil can ignite.