Nearly 130 years ago, the Gilt Edge Mining District in South Dakota beckoned hopefuls from across the country with the promise of mines laden with gold, copper, and tungsten. While some found riches, the operations took a toll on the pristine mountain environment. Millions of gallons of lethal acid rock drainage (ARD) leached into creeks and fisheries, and the mine was eventually declared a Superfund site.
Revolutionizing site cleanup and reclamation, CDM, jointly with the U.S. Environmental Protection Agency and ARCADIS US, Inc., applied an industry first: bioremediation technology that cleans ARD water to stringent standards without a treatment plant. Using an innovative in-situ process that features inexpensive, readily accessible materials, CDM detoxified contaminants in more than 70 million gallons of pit-lake water, producing high-quality surface water capable of sustaining aquatic life—a feat never before possible in the site’s long history.
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An inherently low-cost solution, the innovative process uses readily available products like molasses and alcohol to stimulate bacteria that break down stubborn contaminants.
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Strenuous, year-round testing revealed extraordinary treatment success, transforming once-lethal water into an eco-friendly habitat, able to sustain fish and macroinvertebrates.
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Mine wastes pose a nationwide cleanup burden of $20 billion. The in-situ approach can realize per-site savings of $1 million to $3 million when implemented in lieu of a water treatment plant. The groundbreaking bioremediation solution introduces reliable and affordable treatment to thousands of ARD sites around the world—potentially saving billions of dollars.