"Growing Mounds of Petroleum Coke Raise Fears Along Detroit River"
"Hulking, pitch-black mounds resembling coal have grown exponentially in the last week along the banks of the Detroit River in southwest Detroit, prompting concern about potential pollution from residents and legislators on both sides of the river."
"The petroleum coke, or pet coke, mounds are a by-product of tar sands oil refining used in energy production and when mixed with coal is used as a low-cost fuel.
The piles, brought by trucks loaded with material from the Marathon Petroleum Refinery in southwest Detroit, have been growing on two sites."Source: Detroit Free Press, 03/14/2013