For a year now, Marshall, Michigan, has resembled a town under siege. [...] It’s been like this since last July 25 [2010], when more than 800,000 gallons of crude spilled from a pipeline into a creek that feeds the Kalamazoo River, about 100 miles upriver from Lake Michigan. The EPA ranks it as the largest spill in Midwestern history, but even so, officials say that oil from a typical disaster of that size would have been cleaned up long ago: skimmed, soaked, and vacuumed from the surface.
But this was no typical oil spill. The pipeline owned by the Canadian company Enbridge carried mostly heavy, viscous crude from tar sands fields in Alberta, Canada, bound for Midwestern refineries.
Raw tar sands oil, or bitumen, is so thick that it has to be mixed with a thinning compound, or diluent -- a highly volatile derivative of natural gas that includes large amounts of benzene and other toxic chemicals -- in order to make it liquid enough to pump through pipelines. When that combination, known as DilBit, spilled out of the ruptured pipeline, the benzene and other chemicals in the mixture went airborne,
forcing mandatory evacuations of surrounding homes (many of which were later bought by Enbridge because their owners couldn’t safely return), while the thick, heavy bitumen sank into the water column and coated the river and lake bottom, mixing with sediment and suffocating bottom-dwelling plants, animals, and micro-organisms.
A Year After Pipeline Spill, Tar Sands Oil Still Plagues a Michigan Community | OnEarth Magazine
