Abandoned mines with associated acid mine drainage (AMD) discharges are among the greatest threats to ground and surface water quality in many areas of the United States. While mining is extremely important to our standard of living, energy production, and national security, it can disturb the land and alter the hydrologic balance—affecting the quality and quantity of ground and surface waters in the vicinity of mining operations. Most modern mines are now reclaimed during and after completion of mining activities; but prior to the enactment of environmental laws in the 1970s, most abandoned mines were not reclaimed when it was no longer profitable to retrieve the mineral or coal resources.
Abandoned mine sites, along with associated acidic discharges, must be remediated. To optimize remedial work, state officials should use all available funding sources, develop new funding sources, build partnerships, and remove obstacles that prevent third parties from undertaking activities that address groundwater contamination problems. Future mining and reclamation activities must be planned with a critical eye to environmental and ecological circumstances, using information that incorporates adequate hydrological data, to prevent creation of new acidic discharges.
Such plans should evaluate the impacts or ramifications of mining before the fact and assist the industry in implementing mitigating measures. States should also adopt full-cost bonding requirements, or an equally effective alternative, to reduce the number of mine sites added to the abandoned mine lands inventory through bankruptcy.
WHY ABANDONED MINES MATTER TO GROUNDWATER
Many abandoned coal mines and hardrock mines emit acid mine drainage. This takes place because the rocks associated with both types of mines often contain metal sulfides, such as pyrite. When the rock or coal deposits are excavated, the sulfides are exposed to water and oxygen, and react to form sulfuric acid. Many surface and underground abandoned mines, and their associated spoil and refuse piles, provide an ongoing source of acid mine drainage and toxic heavy metals that can have long-term devastating impacts on groundwater, community water supplies, rivers, streams, and aquatic life.