||Engineering-Science, Inc., Denver, CO. ;Hammer, Siler, George Associates, Denver, CO.;Environmental Protection Agency, Denver, CO. Region VIII.
Typical cyanide heap leach operations for precious metals recovery are described. A hypothetical facility was placed at three sites in the Black Hills of South Dakota to facilitate a discussion of environmental and socioeconomic impacts. Since a cyanide heap leach facility is a closed system and would not, under ordinary operating conditions, discharge fluids to surface or ground water, impacts from a properly designed and operated project would not be a greater threat to environmental quality than industrial developments not using cyanide. Soils, vegetation, and wildlife habitat would be disturbed throughout the life of the project. Most of the adverse impacts to these resources would not continue beyond reclamation. Many safeguards against accidental release of cyanide-containing solutions are incorporated into mine designs. However, in the unlikely event of a spill or leak of cyanide-containing solution, toxic substances could be released to surface and ground waters. Most impacts would be short-term because of dilution and cyanide attenuation. Mine development would have beneficial effects on the economic base but could adversely affect recreation and seasonal housing.