The requests were raised by environmental groups concerning the permit issued by the department last year.
The NorthMet project is located approximately six miles south of Babbitt and one mile south of the existing Northshore (iron ore) mine.
The mine and processing plant proposed by PolyMet is to extract copper, nickel, and precious metals from the NorthMet Deposit in north-eastern Minnesota.
He said that the permits were issued after a comprehensive review and permitting process that involved considerable public involvement and independent review by outside experts.
Cherry continued: “The tailings dam design is configured to achieve and exceed the project-specific factors of safety and stability required by the state. Our proposed tailings basin has undergone more scrutiny and independent expert review than any tailings basin in the state, and arguably, any tailings basin in the country.”
PolyMet plans to reuse the existing tailings basin previously used in taconite mining.
In a separate announcement, the Minnesota Court of Appeals has temporarily put a hold on the company’s water quality (NPDES) permit.
In March 2014, the US Environmental Protection Agency (EPA) issued an EC-2 environmental concerns rating for the NorthMet project, for the supplemental draft of its environmental impact statement.
The company submitted applications for various permits required to construct and operate its NorthMet project in July 2016.