Owned by Enbridge Energy Co. the line runs from Hardisty, Alberta, across northern Minnesota, and ends at an oil terminal in Superior, Wis.

"I am concerned about the potential for disaster," said Harry Miller, a retired Lutheran clergyman from Eagan who was among the activists who sought an extended review of the project. Pipeline opponents led by MN350 asked the commission to force Enbridge to prove before an administrative law judge that the expansion is needed and would be safe.

MN350, which says it's loosely affiliated with the climate change group, 350.org founded by environmentalist Bill McKibben questions the need for the expansion project, saying too much of the oil would be shipped out of state. McKibben and his group 350.org organize against TransCanada's proposed Keystone XL pipeline, which would import the same type of oil through western states.