Talon Metals corporation plans to build nickel-copper mine in coming years. These minerals are bonded to sulfur, forming sulfide minerals and are mined as sulfide ores. When these ores are exposed to air and moisture, a chemical reaction occurs that generates sulfuric acid that migrates into the surrounding environment and, through leaching, releases heavy metals present in the waste rock, pit walls, and tailings basins of mining operations. The sulfuric acid along with dissolved heavy metals released onto the land will seep into the rich aquifers below and then into streams and lakes at levels that are toxic to fish and other aquatic life. This type of pollution is commonly referred to as Acid Mine Drainage (AMD) and has the potential to devastate entire ecosystems. The close proximity of sulfide mines to valued water bodies such as lakes and rivers of the Mississippi watershed intensifies the magnitude of this issue. All of the water bodies in the Tamarack area are linked by multiple aquifers.
Talon Metals corporation proposed Tamarack mine will be located on high ground with surrounding lakes and rivers downstream of the surface water runoff. For example, the topographic map below shows how surface water from the mine will flow down toward Lake Minnewawa, Big Sandy Lake, Round Lake, Horseshoe Lake, the Rice Lake Wildlife refuge, the Mississippi river and many other bodies of water.
When sulfide ores are exposed to air and moisture, a chemical reaction occurs that generates sulfuric acid. Thus, untreated water flowing from the mine facilities will likely be laden with sulfuric acid generating sulfide minerals and other dissolved toxic heavy metals.
Tamarack is a very wet area receiving about 30 inches of precipitation per year. Water from local aquifers will seep into any underground cavity. As such, Talon expects large amounts of water must be pumped to the surface, treated to remove contaminants and somehow disposed of. Page 228 of the Talon Preliminary Economic Analysis (PEA) indicates that the average instantaneous pumping requirements during steady state-mining are between 320 and 370 m3/h with peak flows greater than 400 m3/h or nearly 2.6 million gallons a day. Where does all this water go? How much will lake and well levels drop?
Although Talon has indicated that they might use large industrial Reverse Osmosis water filters to clean contaminated water, they have not included any water treatment facilities in their economic analysis implying that they really don't intend to filter the water. Additionally, they can only clean what they collect and there are plenty of opportunities for contaminated water to be released into the environment.