Strip mining is a form of surface mining that is usually employed for the recovery of materials such as coal and tar sand, which are relatively near the surface of the earth. Surface vegetation, soil, and rocks are removed in strips, often in conjunction with controlled explosions, to make removal more efficient. Once the vein of material is exposed, it is removed and transported to be refined. The technique is somewhat controversial, with pros such as improved efficiency, cost, and safety and cons including the destruction of the natural ecosystem and potential for environmental pollutants.
Proponents of strip mining cite its better efficiency, cost, and safety as compared with traditional underground mining techniques. The recovery rate of materials is higher with strip mining, with approximately 80% to 90% of the material being recovered, as opposed to only approximately 50% with tunnel mining. This process is also much quicker as tunnels do not have to be dug and supported, and minerals are not lifted on long routes up to the surface. Both retrieval and transport are more straightforward with surface mining techniques.
The cost of mining with this method is also lower. This helps to defray production costs and thus, theoretically, the final cost of the material. Strip mining is also safer than underground mining, which can be hazardous due to collapsing tunnels and toxic air. Companies are now required to reclaim any land that they use for strip mining, filling in the removed areas and covering them with topsoil and replanted vegetation.
Critics of this mining method are concerned about its impact and reiterate cons such as the destruction of the natural ecosystem and the introduction of environmental pollutants. Even though companies are required by law to reclaim the land, once fragile ecosystems are disturbed, it can take a number of years to regain equilibrium, resulting in the loss of plant and animal life. If not done properly or if the reclamation takes a significant amount of time, the land becomes vulnerable to erosion and flooding, resulting in further destruction.
Nearby water sources can also become contaminated by the dumping of excavated material and from the use of extraction solvents. Strip mining can also release toxins and dust into the air, resulting in widespread and poorly controlled contamination. Measures are taken to prevent these occurrences, for example, in sealed tailing ponds. These ponds, in which liquid contaminants are placed until they become solid and can be safely removed, are supposed to keep the waste contained; however, leaks have been known to occur and contaminate nearby areas. Whatever the debate, strip mining remains a commonly used and efficient mining method.