Support the Timberjay by making a donation.

Serving Northern St. Louis County, Minnesota

Sulfide ores best mined in the desert

Posted

PolyMet proposes to blast and excavate three open-pit copper mines.  In total, the pits will stretch over three miles and have a maximum depth of 696 feet.  Unlike the copper mines in arid Arizona, these mines in Minnesota will contaminate a water-rich environment.  The mixture of water, air and copper ore will generate toxic sulfide acid mine drainage.

It will be impossible for PolyMet to control and contain all the rain and snowmelt that comes in contact with the huge expanse of terraced walls and floors of exposed copper ore sulfides. In addition, seeping water will flow into and out of the pit as a result of the Earth’s natural cracks and crevices created by erosion and frost heaves.  Continual blasting from the mining operations will further increase the underground rivulets and facilitate the uncontrolled exit flow of toxic wastewater from the copper ore open-pits.

Drill holes around the mine perimeter can monitor some of its seepage.  But fully containing and permanently sealing off seepage 700 feet underground that is draining from the vast exposed weathered surfaces of the pit, is not effective or practical.  Water pumps cannot do the job in totality and the escaping underground toxic water can migrate for miles in any direction.  This water is not confined to flowing in the same direction as water flows on the surface of the watershed above.

In Montana an abandoned open-pit copper mine cavity created an immense rising watery pit of metallic poisons leaching arsenic, lead, and zinc.  No fish live there, no plants live on the periphery and it is lethally toxic for humans.

Miners Lake in Ely, in contrast, formerly part of the Pioneer iron mine, is often cited as a beautiful lake with a variety of fish.  The lake, with a maximum depth of 140 feet, was created in a geological area containing mostly benign iron ore, not sulfide-bearing ore. 

Despite strict adherence to governmental mine regulations, there will be a consequential amount of acidic poison escaping from PolyMet’s copper-sulfide open-pit mining area.  Eventually the surrounding natural environment will be sullied.  At risk are both private and public potable water sources, and the health of animals and fauna, along with recreational water activities.

PolyMet’s copper-sulfide open-pit mines will create an unacceptable environmental impact in a water-rich part of Minnesota famous for its beautiful pristine lakes.  Enforcement of governmental regulations and use of the highest technological applications plus good intentions will not stop the flow of acid waters draining beyond the open pits.  Remember, the Ely Pioneer Mine at times had seepage into the mine of one million gallons of water a day, but the difference is that it was non-lethal, ferrous-based waste water, whereas PolyMet’s copper-sulfide mines’ waste water will be contaminated with a deadly toxic mixture of sulfide-based acidic water with dangerous metals.  We should not let that happen.

Gerry Snyder

Ely, Minn.