The boom-and-bust history of early western mining towns is well preserved in American folklore and song. Unfortunately, that colorful legacy has a darker side that can be seen today in hundreds of abandoned non-coal mines whose metal-laden wastewaters contaminate the delicate ecosystems of the West and pollute thousands of downstream creeks and rivers.

According to the EPA scientists and engineers who have joined in a multi-agency effort to remediate mine waste damage, more than 600,000 U.S. mines have polluted an estimated 180,000 acres of lakes and 12,000 miles of streams. To help meet this environmental challenge, EPA land remediation researchers are testing a variety of risk evaluation and cleanup technologies, some of them through the Engineering Technical Support Center (ETSC) in Cincinnati. A major ETSC challenge is how to treat millions of gallons of acid mine runoff without ready sources of power, in remote locations that are accessible only a few months of each year. Furthermore, in an era of shrinking funding, the treatment technologies must be cost-effective, with low operating and maintenance costs, and be sustainable. One ETSC approach is through the development of new microbial technologies using polymerase chain reaction and DNA/RNA research.

Partnering with other federal agencies such as the U.S. Forest Service, the Bureau of Land Management, the mining industry, and academia, ETSC researchers are testing low-cost and innovative biochemical reactors that combine bacterial reactions with chemical processes (e.g., lime dissolution and chemical precipitate) to increase the pH of the acidic mine water. Sulfate-reducing bacteria precipitate metals from the water by reducing sulfate to sulfide. A by-product of this reaction is bicarbonate, which also increases the pH of acid mine drainage. Here are a few examples of site-specific treatment technologies:

• At the Peerless Jenny Mine in Montana, a four-year test of an innovative design combining a constructed wetlands with a bioreactor has resulted in a completely passive (i.e., gravity-fed) system that requires minimal maintenance and no external energy source. No added chemicals are used in this method, which generates a 50-gallon-per-minute flow of clean water that meets both EPA and state of Montana ambient water quality standards.
• A full-scale rock substrate sulfate-reducing bioreactor system designed by the University of Nevada-Reno and ETSC researchers currently operates at the Leviathan Mine site in California. To maximize the benefits of treating toxic waters and metal precipitation in settling ponds, this bioreactor operates in a recycle mode rather than the passive gravity mode.
• At the Luttrell Repository, which is a 100,000-cubic-yard repository of mine wastes located within the Ten Mile Creek Superfund site in Montana, a leachate collection system sends mine waste runoff to a biochemical reactor for treatment. While the discharge waters from the sulfate-reducing bacteria bioreactor currently meet most clean water standards, research is continuing to develop a more efficient and sustainable bioreactor. Recognizing acid mine drainage from abandoned mines as a long-term environmental issue, industry professionals share the desire of the EPA and other agencies to develop control techniques that meet the demands of individual sites.

National Risk Management Research Laboratory (NRMRL) mine waste researchers have been testing remedial technologies for nearly 20 years in 10 states. Results are shared with the public at workshops and on the web. Since 1998, a series of workshops and conferences have attracted more than 1,600 participants from local and federal government agencies, tribal organizations, universities, the mining industry, and other involved groups. Topics have included mining-impacted pit lakes, mercury and arsenic management in mining, mining-impacted Native American lands, and sustainable modern mining applications.

Today's mining and metals industry is a vital element in the American economy. For further information on risk management approaches to abandoned mine sites and their potential revitalization and reuse, visit the EPA's Abandoned Mine Lands Program (http://www.epa.gov/superfund/programs/aml/).

For further information, contact Patricia Schultz, NRMRL Office of Public Affairs, 513-569-7966.