The Minnesota Department of Natural Resources (DNR) in the US has approved PolyMet Mining's proposed NorthMet project final environmental review saying that it meets the state's standards for adequacy.
The proposed copper-nickel-precious metals NorthMet mine project would be located in the St Louis River watershed on the eastern edge of the Mesabi Iron Range and will include the open pit mine, a processing plant and a tailings basin.
NorthMet development will also include an existing seven-mile-long railroad corridor for ore transport between the mine and the processing plant.
DNR Commissioner Tom Landwehr said: "The environmental review process is about describing the potential environmental effects of the proposed NorthMet project."
"We are confident this document has thoroughly examined the important environmental topics and has addressed them."
DNR's 3,500 page supplemental draft EIS received 58,000 comments and about 4,000 people attended three public meetings in 2014.
Upon receipt of the approval, PolyMet can now begin applying for the permits it needs to go ahead with construction of the mine.
DNR's determination will put an end to the state environmental impact statement process under the Minnesota Environmental Policy Act.
However, the project still needs to obtain more than 20 types of local, state and federal approvals and permits.
The US Forest Service as well as the US Army Corps of Engineers are also required to complete their records of decision.
Prior to approving the project, the DNR reviewed all of the comments received on the final EIS and has also has produced a record of decision that articulates the basis for its adequacy determination.
PolyMet mining president and CEO Jon Cherry said: "We have sought to earn the trust of regulators and the community by listening and being responsive to questions and concerns throughout the environmental review process.
"The EIS demonstrates and confirms that the NorthMet Project can be built and operated in accordance with state and federal regulations."