Buffalo Rock

Strip mining for coal offers us with a valuable resource; however, it has led to destructive environmental problems, namely acid mine runoff. The area immediately surrounding Buffalo Rock State Park is the site of former strip mining activities. Most of the strip mining area, now incorporated in Buffalo Rock State Park, has been reclaimed in accordance with the 1977 Federal Reclamation Act.

Approximately 320 million years ago, during the Pennsylvanian Time Period, plants spread across much of the earth's land surface. Near the water-land contact, plant life was particularly abundant. Plants that died in these wetlands were protected from complete decomposition. The stagnate water was acidic and deficient in oxygen which prevented the growth of bacteria and molds, and provided unfavorable conditions for insects. With time, these remains accumulated on the floor of the wetland, preserved by the lack of oxygen. This accumulation of preserved plant remains is called peat. Peat is used for fuel in areas where trees for firewood are scarce, however, peat contains approximately 70% moisture and other impurities that contribute to a smoky, dirty fire.

With the compaction of overlying strata, peat loses much of its water and changes to a brown colored grade of coal called lignite. Lignite generates less heat per ton than higher grades of coal because of its high moisture content and, like peat, it is a dirty fuel when burned. At higher temperatures and pressures, lignite is converted to sub-bituminous coal, which is lower in moisture than lignite but contains higher volatile matter; volatile matter are substances other than moisture given off as gas and vapor during combustion. At higher temperatures, the sub-bituminous converts to bituminous grade coal, which contains lower moisture content but approximately the same volatile matter. At yet higher temperatures, almost all the moisture and volatile matter is driven off, converting the bituminous grade of coal to anthracite. Anthracite burns with a clean, hot fire because it is almost pure carbon, low in moisture and low in volatile matter. Until 1965 Coal was the most used fossil fuel; since then, coal has been second to oil.

Wetlands trap heavy metals which chemically bond to sulfur as generally insoluble sulfides. As coal is burned, the sulfides such as FeS2 (pyrite) are oxidized producing sulfur dioxide. The equation for the this reaction is: 4FeS₂ + 11O₂ = 8SO₂ + 2Fe₂O₃.

Sulfur dioxide reacts with water in the atmosphere to form sulfuric acid. Sulfuric acid is one of the most common corrosive substances. This reaction follows this equation: 2SO₂ + 2H₂O + O₂ = 2H₂SO₄

Burning coal also releases carbon dioxide (CO₂), a greenhouse gas, into the atmosphere. Coal produces more CO₂ than any other hydrocarbon per energy unit.

Strip-mining for coal, while providing us with an important resource, has contributed to devastating environmental damage. Strip-mining is practiced when coal seams lie close to the Earth's surface. The layers of Earth overlying the coal are removed using standard construction equipment until the coal is reached. The coal is then removed from the ground by hydraulic shovels. The overburden, referred to as mine spoils, is set aside in piles after it has been removed. These spoils consist of natural soil, parent material, and underlying geological material, however, they have a different distribution of carbon, nitrogen, pH level, clay and microorganisms. The spoils also have more rock fragments than natural soils do, and they lack the structure of natural soils. This lack of structure increases runoff and erosion. It is these properties of the spoils that contribute to most of the environmental effects of strip-mining.

Since coal contains sulfur, the rocks directly above the coal are also rich in sulfur because they share the same elements of that environment. As these rocks become exposed at the surface, the sulfide minerals oxidize and sulfates form (i.e., Sulfuric Acid). Since the structure of the spoils decreases infiltration and increases runoff, the rain and snow melts which come in contact with the spoil piles become acidic and run off the piles into streams and rivers. This runoff is commonly called acid mine runoff. It is this acid mine runoff that is the most environmentally detrimental effect of strip-mining.

In Appalachia, there has been approximately 66,500 documented sources of active and inactive coal mines which have polluted an estimated 10,500 miles of streams. In the Midwest, acid mine runoff affects over 5,000 miles of streams and rivers.

Another environmental concern with strip-mining is the amount of sediment that erodes away from these spoil piles. Since the soil and rock in the spoil piles has been disturbed, the energy required to remove sediment is substantially less than if the material remained undisturbed. The effect of this is that a much greater amount of sediment is washed into streams, rivers, and/or lakes.

The Surface Mining Control and Reclamation Act of 1977 (SMCRA) requires that a mined site be restored to a condition of similar topography and equal or greater vegetative production. To reclaim the strip-mined area along the Illinois River by Buffalo Rock State Park, the spoil piles have been graded down, treated with lime to neutralize acids, and seeded with mulch to stimulate the growth of plant life. At this site, the Reclamation has taken on an art form in an Earth Exhibit entitled Effigy Tumuli by Michael Heizer. Heizer selected five native water animals including a snake, turtle, catfish, frog and water strider, which he constructed out of the spoils. The name Effigy Tumuli was given to the exhibit as a tribute to the Native American burial grounds that inspired it. Currently in Illinois, there are 20,000 acres of abandoned mine sites that Federal and State agencies have identified as needing reclamation.