Environmental concerns hound Enbridge pipeline expansion in Michigan DETROIT, Feb. 4 (UPI) -- Environmental campaigners and Michigan residents said they were frustrated that a state regulator gave Enbridge approval to expand a pipeline in the state. A section of Enbridge's Line 6B ruptured in 2010, dumping so-called tar sands oil into the Kalamazoo River and a tributary. The incident was the costliest onshore oil release in history. The Michigan Public Service Commission last week approved an Enbridge application to replace, construct and operate updates to address what it said was the "long-term integrity of the Line 6B pipeline." Michigan residents wrote to The Detroit Free Press saying the MPSC ignored or left out key aspects of a federal study of the 2010 incident. Beth Wallace, a global warming advocate for the Great Lakes region of the National Wildlife Federation, said the Line 6B project should get a federal review given the severity of the spill. The Free Press reports the National Transportation Safety Board said Enbridge knew of line defects before the spill. Pipeline construction is scheduled for late spring.