The long-awaited PolyMet draft environmental impact statement is set for public release by the state Department of Natural Resources later this month, and its release is expected to mark the start of a vigorous debate over the safety of non-ferrous mining in the state.

The state’s public comment period on the EIS is slated to begin Nov. 2, while the federal comment period is set to begin Nov. 6. Comments will be taken for a minimum of 45 days, although the agencies involved are already discussing an extension, according to Stuart Arkley, EIS coordinator for the DNR.

The DNR expects to receive its copy of the draft EIS on Oct. 19, but Arkley said it may take a few days of formatting before it is made available on the DNR website. The document is quite large— close to 1,000 pages, according to Arkley.

The draft EIS is the culmination of more than four years of analysis and input by a number of state and federal agencies, overseen by the DNR and the Army Corps of Engineers. The document examines the impacts of PolyMet Mining’s proposed copper-nickel and platinum-group metals mine near Hoyt Lakes, and considers a number of alternatives and mitigation strategies associated with the proposal.

Major issues considered by the draft EIS include water quality effects from the disposal of sulfide-based tailings, impacts to thousands of acres of wetlands, and loss of wildlife habitat. While the effects of iron mining are quite well-known in northeastern Minnesota, the non-ferrous mining operation proposed by PolyMet poses a different set of environmental challenges, particularly due to the effect of acid drainage. “Water quality, both at the surface and underground, are the big environmental issues,” said Arkley.

Environmental groups have already raised alarms about a number of issues, most prominently acid drainage, which is created as water percolates through sulfide-bearing waste rock, creating sulfuric acid. “What we’re seeing is a lot of problems,” said Betsy Daub, who has closely followed progress on the EIS for the group Friends of the Boundary Waters Wilderness.

PolyMet officials point out that the ore they plan to mine is relatively low in sulfides, compared to other mining operations, averaging 1-2 percent. But Daub contends that other low sulfur mines have proven to be significant polluters.

While sulfides are likely to be a significant point of contention, the issue of sulfates prompted state and federal regulators to propose an alternative to the company’s handling of water from its proposed tailings basin— an alternative that caused one of several delays in completion of the draft EIS. According to Arkley, regulators are concerned that water seeping through the tailings basin will send excessive levels of sulfates into the Embarrass River. Sulfates are known to facilitate the conversion of elemental mercury into the more toxic methyl mercury, which has found its way into many fish in the region.

Some cooperating agencies, including the Great Lakes Indian Fish and Wildlife Commission, have pushed for the consideration of underground mining at the site as a way to reduce some of the environmental effects. Arkley said the option of underground mining was considered, but was not developed as an alternative to the company’s plan for open pit mining.

Both the DNR and the Army Corps will be holding public hearings on the draft EIS as part of the public comment phase, with one set to be held in Hoyt Lakes and the other in the Twin Cities. Dates, times, and locations on those meetings will be released once the EIS is officially published.

The Timberjay will be providing much more information on this issue as it becomes available.