Enbridge aims to replace hundreds of miles of Line 6B under a $268 million plan that would upgrade the pipeline's safety features and increase its volume to 500,000 barrels of oil per day.
A section of the pipeline ruptured in 2010, dumping so-called tar sands oil into the Kalamazoo River and a tributary. The nature of that type of crude oil causes it to sink in water and the incident was the costliest onshore oil release in history.
Enbridge, in a letter the Detroit Free Press says was sent to local leaders, said its pipelines were safe.
"Enbridge disagrees with the assertion that the design of the replacement segments (of Line 6B) falls short of enhancements that Enbridge committed to on another project crossing the Rocky Mountains in remote areas of Alberta and British Columbia, Canada," the letter states.
The Free Press reports that authorities in eastern Michigan passed a resolution calling on Enbridge to meet or exceed standards embraced for other projects planned by the company.
The U.S. Pipeline and Hazardous Materials Safety Administration said this week that Enbridge paid a $3.7 million penalty for the 2010 incident. U.S. investigators suggested the company knew of line defects five years before the accident.