In Indiana, coal is produced by both surface mines and underground mines. In 2002, about 76 percent of Indiana's coal production was from surface mines. Surface mining affects vegetative cover, soil characteristics, surface drainage, and ground water. Public controversies also occasionally arise regarding the effects of blasting. Underground mining has the potential to cause subsidence of the land.
The Indiana Department of Natural Resources (IDNR), Division of Reclamation (DOR)administers coal mining and land restoration programs for both active and abandoned coal mining operations. Active operations are regulated under the federal Surface Mining Control and Reclamation Act (P.L. 95-87), and the Indiana Surface Mining Law (IC 14-34). The DOR has prepared a pamphlet titled Citizens Guide to Coal Mining and Regulation in Indiana.
Other agencies having major roles in the regulation of coal mining include the IDNR Division of Water, the Indiana Department of Environmental Management (IDEM), and the federal Mine Safety and Health Administration (MSHA).
Coal and Ground Water
Whether by surface or underground methods, coal mining can have profound effects on both ground water and surface drainage. In the past, coal mines and coal-preparation facilities produced acidic mine drainage that contaminated streams and water wells, left areas barren of vegetation, increased erosion, and caused siltation of streams.
Since 1977, implementation of the Surface Mining Control and Reclamation Act under the U.S. Department of the Interior, Office of Surface Mining has greatly reduced the hydrologic problems formerly associated with coal mining. The Indiana Department of Natural Resources, Division of Reclamation (IDOR) administers coal mining and land restoration programs for both active and abandoned coal mining operations. Many of the water-related problems created by past mining have been addressed by the IDOR through the Abandoned Mine Land (AML) Program, which deals with problems created prior to 1977.
Together with IDOR, the Indiana Geological Survey has been involved in a series of AML projects to assess the hydrologic effects of reclamation. For an example of such a project.
Septic Systems in Surface-Mine Areas
Procedures have been developed for evaluating the suitability of natural soils for on-site septic systems, but the suitability of certain disturbed or man-made soils is uncertain. The Indiana State Department of Health, Sanitary Engineering, Residential Sewage Disposal Section has been investigating the hydrologic characteristics of mine spoil (the disturbed overburden from surface mining).
An investigation of the suitability of mine spoil for septic systems is described in Hydrologic Suitability of Mine Spoil as a Medium for Septic-Tank Absorption Fields, Warrick County, Indiana.
Ash Disposal in Mines
The disposal in mines (active and abandoned) of coal ash from power plants has been a contentious issue in Indiana in recent years. Some environmental groups have argued that disposing ash in coal mines could introduce contaminants into ground water. For current practices regarding the disposal of ash in active coal mines, contact the Indiana Department of Natural Resources, Division of Reclamation.
A project to investigate the effects on ground water of ash used to reclaim an abandoned coal mine is described in Hydrology and Water Quality Associated with the Midwestern Reclamation Site (Site No. 1087) Pike County, Indiana.
Coal-Bed Methane Gas
Methane is the primary component of natural gas; it is created from the decomposition of organic matter. Coal-bed methane gas is produced during coalification, the natural process that transforms plant material into coal.
Coal-bed methane can accumulate in underground coal mines and cause explosions. For this reason, the federal Mine Safety and Health Administration requires coal mines to exhaust coal-bed methane from mines if concentrations of the gas reach certain levels.
Coal-Bed Methane for Energy
Currently, natural gas is considered to be the most desirable of the fossil fuels, because it is thought to be better for the environment. Within Indiana, the construction of new gas-fired merchant power plants is significantly increasing the demand for natural gas in the state.
Because of increased demand for natural gas, there has been a surge of nationwide interest in the development of coal-bed methane (CBM). As reserves of natural gas decline, CBM could fill an important role in domestic energy production. Currently, CBM is estimated to be meeting 9 percent of the dry natural gas demand in the United States, and the production of Indiana's coal-bed methane could provide additional supplies for energy generation.
Because extraction of methane from coal beds involves pumping out large quantities of water that is sometimes saline, economical methods for environmentally responsible disposal of such water are being investigated. Another environmental concern is that nearby aquifers can become contaminated from coal-bed methane operations. Information about these and other issues is available from the United States Geological Survey.
The amount and proportion of gases in the atmosphere influences global climate. Changes in the proportions of certain gases may be contributing to climate change, including a gradual warming of the atmosphere, referred to as the "greenhouse effect." Of particular interest are changes in the amount of water vapor (H2O), carbon dioxide (CO2), methane (CH4), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), sulfur hexafluoride (SF6), and others. Some of these gases are naturally occuring, while others are man-made.
Carbon dioxide (CO2) is produced by many natural and man-made processes, including combustion of fossil fuels. Besides reducing fossil-fuel emissions, there are a number of technologies under investigation for preventing carbon dioxide from entering the atmosphere.
Geologic sequestration involves the capture of carbon dioxide and its storage in natural pore spaces in geologic formations; this method of sequestration is thought to have the best potential for near-term application. The IGS is involved in research on geologic sequestration as part of the MIDCARB Project. Information is also available from the U.S. Department of Energy, Office of Fossil Energy.