A MULTIDISCIPLINARY APPROACH TO SCREENING AND CHARACTERIZATION OF WEATHERED METAL-MINING WASTE PILES

Thousands of historical mine-waste piles are present on inactive metal-mining sites in the United States. Release of dissolved metals, acidity, and suspended particulates from these mine-waste sites is a potentially serious problem for receiving waters. Consequently, the accurate characterization and assessment of metal mobility, acid-drainage production, and toxic effects from the weathering of mine-waste piles is an area of growing need as the environmental effects of inactive mine-waste sites across the country continue to be evaluated and mitigated. The U.S. Geological Survey Mine Waste Characterization Project has taken a multidisciplinary approach to assemble, develop, and refine methods and tools for characterizing and screening weathered solid-mine wastes. Researchers from a variety of disciplines, including geophysics, geochemistry, analytical chemistry, geology, mineralogy, geomicrobiology, remote sensing, and aquatic toxicology have worked together at several mine-waste sites to develop an integrated "tool kit" for the rapid and effective characterization of these sites' effects. Detailed studies have been conducted at eight sites, representing both igneous-hosted and carbonate-hosted polymetallic sulfide deposits. The carbonate-hosted sites enabled us to evaluate the possible mitigating effects of carbonate minerals. Two of the sites are located in a drier climate and allowed us to examine the influence of climate on mine-waste weathering processes. Findings from this work will assist land managers, industry, and regulatory agencies in ranking and prioritizing mine-waste piles for remediation.