Gov. Mark Dayton will inspect hard-rock mines in Michigan and South Dakota this week in preparation for what he calls the "most momentous, difficult and controversial decision" of his tenure: Whether to approve a controversial proposal by PolyMet Mining for northern Minnesota.
The two operations, chosen by opposing advocacy groups, will show Dayton the best and worst environmental consequences of modern mining and help him evaluate the risks associated with PolyMet's plan.
Both mines offer valuable lessons, Dayton said, but PolyMet's plan to harvest copper and nickel from Minnesota's northwoods will be judged on its own merits as state regulators enter the final stage of approvals next month. The Dayton administration expects to complete a 10-year environmental review and start making decisions that could move the project forward, including a linchpin permit to mine.
"I'm genuinely undecided," Dayton said in an interview. PolyMet's proposal has triggered hopes of a mining comeback on the Iron Range, but also sowed deep fears about the environmental risks posed by a type of mining that would be new to Minnesota. "I can't help but think this will be very educational."
The governor's tour starts Tuesday at a failed gold mine near Deadwood, S.D., that has cost taxpayers more than $105 million for pollution cleanup and continues to cost more than $2 million per year. The Gilt Edge Mine — a large, deep open-pit operation — was abandoned by its owner in a 1999 bankruptcy and became a Superfund site under the U.S. Environmental Protection Agency. Superfund managers will give Dayton a guided tour.
Mining at Gilt Edge dates back to the late 1800s. But Dayton will focus on a modern period in which there were dreadful environmental miscalculations leading up to the 1986 commencement of operations by Brohm Mining Co., said Betsy Daub, policy director at Minneapolis-based Friends of the Boundary Waters Wilderness.
Daub said the company mistakenly assured regulators that local rock was low in sulfide content. Instead, the mining of high-sulfide rock caused uncontained sulfuric acid runoff into the area's cold-water trout streams. As at many metal mines, the acid forms when sulfide rock is exposed to air and water, creating pollution that can persist for hundreds of years.
South Dakota demanded that Brohm install a water treatment facility to address the problem, but the extra expense, combined with falling gold prices, put the mine out of business, according to officials from the South Dakota Department of Environment and Natural Resources.