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Surface Mining1 Major Challenges in Landscape Planning: Simulated Field Trips 1 Surface Mining 2/ Robert Leopold, Bruce Rowland and Reed Stalder Abstract: The surface mining process consists of four phases: (1) exploration; (2) development; (3) production; and (4) reclamation. A variety of surface mining methods has been developed, including strip mining, auger, area strip, open pit, dredging, and hydraulic. Sound planning and design techniques are essential to implement alternatives to meet the myriad of laws, regulations, and mining and visual resource objectives. INTRODUCTION OVERVIEW OF SURFACE MINING Our brief slide introduction of various Stated in the simplest terms, surface mining activities should reinforce your con- mining consists of removing the topsoil, rock, viction(s) that management of the visual and other strata called overburden that lie resource in conjunction with surface mining above mineral or fuel deposits to recover is a feasible and necessary undertaking. We them. have far too long stressed the negative; the time is now to stress the positive. When compared to underground methods, surface mining offers several advantages: it The purpose of this simulated visual (1) allows recovery of deposits which cannot field trip is to increase the audience's be deep-mined; (2) it usually results in a more (1) understanding of the surface mining complete recovery of the deposit; and process; (2) sensitivity to surface mining- (3) generally, lower cost per unit of related visual impacts; and (3) awareness of production. visual impact mitigation and design practices and planning techniques. The surface mining process generally consists of four phases: (1) exploration; (2) development; (3) production; and (4) reclamation. The purpose of exploration or "prospec- ting" is to discover, delineate, and prove the ore body. Exploration techniques vary with the commodity and its geographic location. l/ Presented at the National Conference on These include remote sensing or on-site mapping, Applied Techniques for Analysis and Management core drilling to intersect deeper-lying ore of the Visual Resource, Incline Village, bodies, or excavating shallow trenches or pits Nevada, April 23-25, 1979 to expose the ore. For example, uranium ex- ploration in the West combines aerial geo- 2/ physical mapping and core drilling. Chief, Division of Planning and Environ- mental Coordination Colorado State Office During the development phase, detailed Bureau of Land Management, Denver, Colo.; mining and reclamation plans are developed, Landscape Architect, Tennessee Valley access and haul roads are constructed, and Authority, Division of Natural Resources support facilities and structures are built. Services, Norris, Tenn.; State Landscape Architect, Utah State Office, Bureau of Production is a four-step process, Land Management, Salt Lake City, Utah. including: (1) site preparation to remove vegetation and other obstructions, and to prepare sites for spoil or waste disposal; (2) blasting and removing overburden; (3) excavating and 20 loading ore; and (4) transporting the ore to (3) Area strip mining is used in flat or a processing plant, storage area, or to market. rolling terrain where the deposits are exten- sive and lie relatively near the surface. A Reclamation involves restoring the land trench is made through the overburden, exposing to productive use and controlling on-site and the deposit which is then removed. As each off-site impacts. Reclamation problems and succeeding parallel cut is made, the spoil is techniques vary with the type of mineral, deposited in the previous cut. The final cut mining method, regional climatic differences, leaves an open trench and a highwall. Prior and regulations. to reclamation, the area from the air appears to have been subjected to a giant plow with For example, regulations which resulted furrows reaching a depth of 100 feet or more. from enactment of the Surface Mining Control Eastern phosphate, western coal, and some and Reclamation Act of 1977 require surface clays and iron ore are mined using this method. coal mines to be reclaimed back-to-approximate original contour. Successful reclamation In recent years, a combination of area depends in large part on accurate identifica- and contour strip mining methods called tion of the physical and chemical characteris- mountaintop removal has been employed to tics of the overburden and effective segrega- recover coal in southern Appalachia. This tion of material which will support re- method is often used when the coal lies establishment of vegetation. close to the ridge of the mountain, thus allowing economical removal of the overburden A variety of surface mining methods has above the entire seam. been developed to handle effectively the diversity of geologic, topographic, and (4) Open pit mining, also called quarry- climatic conditions inherent in the location ing, is similar to area strip mining, but it of various minerals. These include: is generally conducted in a localized area (1) contour strip mining; (2) auger mining; resulting in large vertical pits. Unlike (3) area strip mining; (4) open pit mining; area strip mining, the amount of overburden (5) dredging; and (6) hydraulic mining. removed is proportionately small compared with the quantity of ore recovered. In many (1) Contour strip mining is used in cases, large quantities of ore are obtained hilly or mountainous terrain where the within a relatively small surface area because mineral lies in beds or seams. The overburden of the thickness of the deposits. In addition, is removed beginning where the mineral outcrops open pit mines are generally in operation over on the surface and proceeds into the mountain much longer periods of time, often decades. until the cost of removing the overburden Limestone, sandstone, marble, granite, sand exceeds the value of the deposit to be re- and gravel, iron ore, copper, uranium, mica, covered. In the past, this unconsolidated sulfur, and some phosphate are mined using material was cast down the outslope as spoil. this method. Once exposed, the deposit is loosened and removed. This creates a bench on the mountain- (5) Dredging is a water-oriented mining side with an associated highwall, sometimes operation that uses a suction apparatus or exceeding 100 feet in height, which marks the various mechanical devices such as buckets, lateral extent of overburden removal. This clamshells, and draglines mounted on floating process is continued generally on contour barges to recover the deposits. Tailing around the mountainside. Coal in Appalachia piles left at mine sites resemble spoil piles and phosphate in the West are mined using created during area strip mining for coal. this method. This technique is often used to mine gold and sand and gravel. (2) Auger mining is often performed in conjunction with contour strip mining. When (6) In hydraulic mining, a powerful jet the economics of mining stop the stripping, of water is used to erode a bank of earth or the operator sometimes chooses to extract gravel which is either the overburden or more of the deposit by boring horizontally contains the desired mineral. Ore- into the seam where it is exposed at the bearing material is fed into slurries or base of the highwall, like a carpenter bores other concentrating devices where the desired a hole in wood. However, it is an extremely product is separated from the tailings wasteful technique. For example, augering coal (waste). Although extensively used in the may recover only 40 per cent of the seam, leaving past to mine gold, it is a practice that has the remaining 60 per cent in a condition that makes been virtually eliminated today. it unrecoverable by existing mining techniques. To date, an estimated 6.5 million acres of land, approximately 10,000 square miles 21 or roughly the size of Maryland, have been In the past, improper placement of over- disturbed in the United States by surface burden and topsoil, exposure of toxic materials, mining activities and associated access and inadequate drainage and revegetation have facilities. As of 1971, 90 per cent of this acreage resulted in many environmental impacts, in- was attributed to seven commodities: coal, cluding landslides, erosion, stream siltation, sand and gravel, stone, copper, clay, phos- and acid mine drainage. phate, and iron ore. The current estimated rate of disturbance, which is 225,000 acres In the exploration phase, visual impacts annually, will increase in future years. are generally slight, due to the limited dis- turbance caused by drilling, trench excavating, Over 50 types of minerals and commodi- and access road development. ties are recovered by surface mining methods. Their nature, extent, and geographic distri- The visual impact of the mining process bution vary widely. For example, coal in becomes more intense in the development and different forms is found scattered throughout production phases due to the large amount of the eastern, midwestern and western portions land disturbance. of the United States in 34 states. Although one of the goals of reclamation As our society becomes more complex in is to reduce visual impacts, the visual con- its industrial and technological development trast between reclaimed areas and surrounding and needs increased energy sources and undisturbed areas often remains for many years. independence, the pressure to recover our natural resources will intensify. This Changes over time in the mining process inevitably means that surface mining will due to advances in technology
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