One of the most controversial Minnesota projects in recent years is the proposed PolyMet mine on the Iron Range. The NorthMet Project calls for surface mining and mineral processing of approximately 228 million tons of copper-nickel-Platinum Group Element (PGE) ore over approximately a 20-year mine life.
The project would be the first large-scale nonferrous metallic mineral mine in the state of Minnesota. PolyMet Mining Inc. expects to mine, on average, 91,200 tons per day (tpd) of material, which would include about 32,000 tpd of ore and 3,900 tpd of overburden and 55,300 tpd of waste rock.
Annually, this would result in the removal of about 19.7 million tons of waste rock and 1.4 million tons of overburden, although most overburden would be stripped during the construction period at the beginning of the project. Operating at these rates, annual metal production would total about 38,821 tons of copper, 9,037 tons of nickel, 400 tons of cobalt, 22,184 ounces of platinum, 87,129 ounces of palladium, and 13,824 ounces of gold.
Environmentalists are lined up in opposition to PolyMet, viewing its project as a serious threat to water quality in the entire region, including the Boundary Waters Canoe Area Wilderness. Project advocates include Rep. James Oberstar, Sen. Amy Klobuchar, Gov. Tim Pawlenty and others who are mindful of thousands of new quality jobs on the depressed Iron Range.
There are valid arguments against the PolyMet project. Perhaps the most negative is the financial status of PolyMet, a relatively small corporation for whom this is the major activity. PolyMet will have to meet the substantial commitments of the project, which are described in the Draft Environmental Impact Statement (DEIS). There is also the final closure and remediation, which is estimated to cost $50 million, and then the long — more than 1,000 years per the DEIS — follow-up of drainage from left over tailings and newly created storage ponds.
It is clear from the 714-page DEIS from the Minnesota DNR and the Corps of Engineers that all of the effluent from the project ends up in the drainage areas of the Partridge and Embarrass Rivers. Those rivers flow south to the St. Louis River and Lake Superior, not north to the Boundary Waters.
The DEIS has both positive and negative comments about the project, but in general it suggests that IF all of PolyMet’s commitments are met, there is no serious impact on the environment. The following quote from page 244 of the DEIS sums up comments about the rivers involved:
“Even with these higher loadings and assuming no natural attenuation, the model results indicate that water quality standards for the Partridge River would be maintained for the eight constituents studied (i.e., antimony, arsenic, fluoride, cobalt, copper, nickel, vanadium, and sulfate) under all flow conditions and mine years modeled. Therefore, even using relatively conservative assumptions, the Proposed Action is not predicted to result in any exceedances of surface water quality standards for the Partridge River at the modeled locations.”
Rolf Westgard of St. Paul is a professional member of the Geological Society of America.