Impacts of Mining This Section Will Discuss the Impacts of Mining, and Some of the New

Impacts of Mining ~ This section will discuss the impacts of mining, and some of the new regulations that certain states are starting to enforce.

With an increase in U.S. energy requirements, particularly thedemand for coal to fuel power plants that produce electricity, thescale of surface mining has grown. So, too, have the potentialenvironmental effects of mining. For example, surface coal miningrequires the removal of enormous amounts of soil and rock toreach near-surface coal seams.Because of the environmental impacts of mining on such alarge scale, mining has become one of the most heavily regulatedindustries in the United States. Mining companies now spendlarge amounts of money to preserve the environment. Reclaimingthe land, or returning the land to its original condition after miningis completed, is part of every surface coal mining operation.

Before mining, companies develop a plan to reclaim the land.Even before mining is complete, this plan is put into action. Withenvironmental preservation now a clear goal of mining companies,future generations of Americans will not have to view scarsin the Earth, such as the one shown in Figure 14.Figure 14 _ At 215 m deep and1.6 km in circumference, the “BigHole” at the Kimberley Mine in SouthAfrica is the largest hand-dug excavationin the world. By the time themine closed in 1914, 22.5 milliontons of rock had yielded almost3,000 kg of diamonds.

Types of Pollution Caused by Mining

Air and Noise Pollution

Surface mining can cause both airpollution and noise pollution. At surface coal mines, removing, loading, hauling, and dumping soil and overburden producedust. Winds that blow across unreclaimed soil and overburdenstorage areas also produce dust. Loading, hauling, and unloadingore create dust emissions at open-pit mines. As well, dust iscreated in open-pit mines when the ore is blasted apart.Noise is created by the equipment that is used in a mine aswell as by blasting. Whereas equipment noise may be a nuisance,blasting can cause physical damage to nearby structures.Because of air and noise pollution, most surface mines are notlocated near urban populations. More important, regulations inthe U.S. forbid mining operations to allow dust or noise to exitthe area that is being mined.

Water Contamination

Water resources can be negativelyimpacted by mining. Water that seeps into mines or through pilesof excess rock can pick up or dissolve toxic substances likearsenic. These contaminants can wash into streams, where theycan harm or kill aquatic life.Coal or minerals that contain a lot of sulfur can cause asimilar problem. When these materials react with oxygen andwater, they form dilute sulfuric acid. This acid can dissolvetoxic minerals that remain in mines and excess rock. The contaminated water that results from this process is known as acidmine drainage, or AMD. An example of AMD is shown inFigure 15. Mining regulation in the U.S. requires companies todispose of acid-producing rock in such a way that water is notcontaminated.

Displacement of Wildlife

Removing soilfrom a surface mine site strips away all plantlife. With their natural habitat removed, animals will leave the area. In addition, whenmining is completed and the soil is returnedto the mine site, different plants and animals may establish themselves, which creates anentirely new ecosystem. However, a gooddevelopment plan to reclaim a mine site can

ensure that the displacement of wildlife ismerely temporary.Dredging can negatively affect aquatic ecosystems and physically change the bottomsof rivers. Dredging disturbs riverbottoms and destroys aquatic plant life in the dredged portion of the river. The disturbance of a riverbed can cause sedimentsto contaminate a river for up to 10 km.

Why does surface miningcause animals to leave an area?

Erosion and Sedimentation

Excess rock from mines is sometimesdumped into large piles called dumps. Running water erodes unprotected dumps and transports sediments into nearbystreams. The sediments may harm water quality and aquatic life.

Soil Degradation

Soil at a mine site is removed from the uppermostlayer downward. When this soil is stored for later reuse, care must be taken to ensure that the upper soil layers are notburied beneath soil layers that were originally below them. In thisway, the soil layers that are richest in important nutrients are notcovered. If soil is not removed and stored in separate layers, the soil may be nutrient poor when it is reclaimed.Minerals that contain sulfur may be found in deeper soil layers. If these minerals are exposed to water and oxygen in the atmosphere, chemical reactions result in the release of acid, whichthen acidifies the soil. When the acidified soil is returned to the mine site, it may be difficult for plants to grow.

How might exposing deep soil layers to the air prevent plants from growing?

Subsidence

The sinking of regions of the ground with little orno horizontal movement is called (suhbSIED’ns).Subsidence occurs when pillars that have been left standing inmines collapse or the mine roof or floor fails.Buildings, houses, roads, bridges, underground pipelines, andutilities that are built over abandoned mines could be damaged ifthe ground below them subsides. In November and December2000, underground limestone mines that were several hundredyears old collapsed in Edinburgh, Scotland. The collapse causedproperty damage and forced people to evacuate their homes.Figure 16 shows the potential effects of mine subsidence.

Underground Mine Fires

Fires that start in underground coalseams are one of the most serious environmental consequences of coal mining. Lightning, forest fires, and burning trash can allcause coal-seam fires. In addition, fires can start by themselves when minerals in the coal that contain sulfur are exposed to oxygen.These fires are hard to put out and are often left to burnthemselves out, which may take decades or even centuries. Forexample, a fire that has been burning through an undergroundcoal seam in an Australian mountain is estimated to be 2,000years old! Underground fires that burn their way to the surfacerelease smoke and gases that can cause respiratory problems.