THE IMPACTS OF HARDROCK MINING IN EASTERN TENNESSEE: INTEGRATED STUDIES OF DAVIS MILL CREEK AND THE COPPER BASIN MINE SITE

The Copper Basin, located in SE Tennessee, hosted nearly 150 years of underground mining, mineral processing and chemical production. These operations created environmental impacts over an area of nearly 50 square miles. Areas of continuing degradation include the Davis Mill Creek (DMC) watershed, North Potato Creek watershed and Ocoee River. Since 1999, we have been evaluating impacts to DMC and the Ocoee River and developing appropriate interim remedial actions to support final remedies.

Underground mines, and smelting, acid and other chemical production facilities, were located in the DMC watershed. DMC also served as one of the main disposal sites for a variety of solid waste materials and by-product stockpiles, including slag, iron calcine, treatment plant sludge, demolition debris, sulfide concentrate, and waste rock. Over time, the locations and nature of production facilities changed as new technologies were developed to process Basin ores, and the morphology of the watershed was extensively modified through waste disposal to accommodate growth of the production facilities.

To address the DMC watershed, we adopted an integrated approach that combines historical research and field studies. Historical research has been used to define changes in process methods, waste disposal locations and practices, and geomorphology. Historical information was gathered from topographic maps extending back to 1906, aerial photos from 1938 onward, ground photos beginning in 1901, and information provided by long-term employees. Field studies are aimed at identifying the nature and extent of contamination, understanding contaminant release from solid wastes, soils and sediments, transport mechanisms in surface water and shallow ground water, and impacts to aquatic life. In addition to typical sampling and analysis, field studies included Basin-wide determinations of field water quality parameters and mapping waste materials in DMC. Integrating these data sets is accomplished using GIS to display historical changes in natural features, assist in calculations of waste volumes, view anthropomorphic changes to the watershed, and display geochemical variations in the different environmental media across the watershed. The integrated approach has permitted a clearer understanding of changes in stream location, substrate morphology and water quality with time.