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Strip mining Environmental Encyclopedia. 2011. COPYRIGHT Gale, Cengage Learning Updated: Aug. 30, 2017

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This technique is used for near-surface, relatively flat sedimentary mineral deposits. How deeply the mining can occur is essentially determined by the combination of technological capabilities and the economics involved. The latter includes the current value of the mineral, contractual arrangements with the landowner, and mining costs, including reclamation. Strip mining is used for mining phosphate fertilizer in Florida, North Carolina, and Idaho, and for obtaining gypsum (mainly for wallboard) in western states. However, the most common association of strip mining is with coal. The examples of decimated land in Appalachia have motivated calls for prevention, or at least major efforts at reclamation. Strip mining for coal comprises well over half of the land that is

strip-mined, which totaled less that 0.3 percent of land in the United States between 1930 and 1990. This is far less land than the amount lost to agriculture and urbanization. However, in agriculturally rich areas such as Illinois and Indiana there is a growing concern over the one- time disruption of land for mineral extraction, compared to the long term use for food production. Strip mining has occurred mainly in the Appalachian Mountains and adjacent areas, the Central Plains from Indiana and Illinois through Oklahoma, and new mines for subbituminous coal in North Dakota, Wyoming, and Montana. Important mining is also carried out on Hopi and Navajo lands, notably Black Mesa in northeastern Arizona. In addition to the United States, the process is used in Canada, Germany, and other countries with coal or other deposits near the surface. Despite the small amount of land used in strip mining, the process radically alters landforms and ecosystems where it is practiced. Depending on state laws, mining landscapes prior to 1977 were often left as is, dubbed "orphan lands." The 1977 act required the land to be restored as closely as possible to the original condition. This is a nearly impossible task, especially when one considers the reconstruction of the preexisting soil conditions and ecosystem. Even so, reclamation is a vital first step in the healing process. Generally, the steeper the terrain, the greater the impact on the landforms and river systems, and the more difficult the reclamation. Detailed economic planning precedes any strip mining effort. Numerous cores are drilled to determine the depth, thickness, and quality of the coal, and to assess the difficulty of removing the overburden, which consists of topsoil and rock above the resource. If caprock is encountered, expensive and time-consuming blasting is required, a frequent occurrence in the United States. Economic analysis then determines the area and depth of profitable overburden removal. Finally, contracts must be negotiated with landowners; strip mines commonly end abruptly at property lines. Two kinds of earth removal equipment are typically used: a front-loading bucket (the classic steam shovel), or a dragline bucket that pulls the material toward the operator. Power shovels and draglines built prior to World War II generally have bucket capacities of 30-50 cubic yards (23-38 m​3​). Post-World-War-II equipment may have a capacity up to 200 cubic yards (153 m​3​). A new development, encouraged by the 1977 reclamation law, is the combination of dozers and scrapers (belly loaders) more commonly seen on road-building or construction sites. After the overburden is removed, mining begins. The process is conducted in rows, creating long ridges and valleys in the countryside that resemble a washboard. Coal extraction follows behind power shovels, leaving a flat, canyon-like cut. Upon completion of a row, the shovel starts back in the opposite direction, placing the new

overburden in the now-empty cut. In hilly terrain, only a few cuts are all that is usually profitable because the depth of overburden increases rapidly into the hillside. Since the worst complications as a result of strip mining occur on hillsides, the environmental price for a limited amount of coal is very high. Hillside mining such as this is called "contour mining," in contrast to "area mining" on relatively flat terrain. In the latter, the number of rows are limited mostly by contractual arrangements. Consequently, the main difference between area and contour strip mining are the number of rows and the steepness of the terrain. Both types of strip mining leave behind four basic land configurations: (l) spoil bank ridges; (2) a final-cut canyon often partially filled by a lake; (3) a high headwall marking the uphill end of the mining; and (4) coal-haul roads, usually at the base of the outermost spoil bank and through gaps in the spoil-bank rows left for this purpose. In some orphan lands, wilderness-like conditions prevail, where trees populate the spoil banks and aquatic ecosystems thrive in the final-cut lake. Left alone by man, these may afford a surprisingly rich habitat for wildlife, especially birds. Deer thrive in some North Dakota abandoned mines. Reclamation of area mining is relatively simple compared to contour strip mining. Prior to mining, the topsoil is removed and stockpiled. The overburden from the initial cut may be used to fill in the final cut, and the top part of the headwall is sometimes cut down to grade into the spoil. The spoil banks are leveled and the topsoil replaced; fertilization and replanting, usually with grasses or trees for erosion control, and subsequent monitoring of revegetation efforts, complete the process. In large operations, the leveling and replanting coincide with mining, which is ideal since this rapidly rebuilds the vegetation cover. Reclamation of contour mining presents far greater difficulties, primarily because of the slope angles encountered. Research in Great Britain revealed that even well-vegetated slopes were producing fifty to 200 times as much sediment as similar, undisturbed slopes. Furthermore, the greater slope angles allow much more of the sediment to reach the channel below, where it eventually flows into streams and rivers. Another problem for orphan lands in hilly terrain is the ecological island left when hills are completely enclosed by high headwalls. This is not unlike the ecological islands created in the southwestern United States from climate changes and vertical zonation of vegetation. Though far more recent, ecologists hope these "orphan islands" will allow interesting case studies of genetic isolation.

Resources

Books ● Barnes, Michael. ​Fortunes Found: Canadian Mining Success​. Renfrew, Ont., Canada: General Store Pub. House, 2010. ● Bondarenko, Volodymyr. ​New Techniques and Technologies in Mining​. Boca Raton, Fla., and London: School of Underground Mining, CRC Press, 2010. ● Burke, Barlow. ​Law and Regulation of Mining: Minerals to Energy​. Durham: Carolina Academic Press, 2009. ● Campbell, Bonnie K. ​Mining in Africa: Regulation and Development​. London and New York: Pluto Press, 2009. ● United States Congress, Senate Committee on Health, Education, Labor, and Pensions. ​Current Mine Safety Disasters: Issues and Challenges: Hearing before the Committee on Health, Education, Labor, and Pensions, United States Senate, One Hundred Tenth Congress, First Session, on Examining Issues and Challenges Facing Current Mine Safety, October 2, 2007​. Washington, DC: U.S. Government Printing Office., 2009. Periodicals ● Dhillon, Balbir S. "Mining Equipment Safety: A Review, Analysis Methods and Improvement Strategies." ​International Journal of Mining, Reclamation and Environment​ 23, no. 3 (January 2009): 168-179. Other Centers for Disease Control and Prevention (CDC). "Mining." http://www.cdc.gov/niosh/mining/index.html (accessed January 21, 2015). ● United States Department of the Interior, United States Geological Survey (USGS). "Mining Hazards." http:https://www2.usgs.gov/science/science.php?term=750 (accessed August 21, 2017). ● United States Department of the Interior, United States Geological Survey (USGS). "Mining and Quarrying." https://minerals.usgs.gov/minerals/pubs/commodity/m&q/ (accessed August 21, 2017). ● National Geographic Society. "Mining's Hard Rock Legacy." http://science.nationalgeographic.com/science/earth/inside-the-earth/hard-rock.ht ml (accessed August 21, 2017). ●

Source Citation​ (MLA 8​th​ Edition) "Strip mining." ​Environmental Encyclopedia​, edited by Deirdre S. Blanchfield, Gale, 2011. ​Science In Context​, http://link.galegroup.com/apps/doc/CV2644151322/SCIC?u=j043905001&sid=SCIC &xid=0242c5ac. Accessed 23 May 2018. Gale Document Number: ​ GALE|CV2644151322