Regulatory standard, private or community agreement, or the goals of the mining company may define successful reclamation. Surface mining requires handling the entire surface and overburden mass above the coal seam. Reclaiming and restructuring this mass offers a greater opportunity to select and structure the land for the needs and purposes of the human and natural community than would be available in almost any other way. Selecting a post-mining land use must be based on cultural factors in the surrounding community, subject to the constraints of the environment that are beyond human control.

Regulations and Bonding: In more stringently regulated countries, reclamation standards may be one of the most significant factors in selecting post-mining land use. The most common method of applying regulatory control is to require approval of any proposed mining plan by various local, provincial, and national government agencies prior to beginning mining in Australia, Canada, the European Economic Community, South Africa, and the US. Increasingly these laws are being used as patterns for environmental preservation legislation around the world. Some laws, for example those of Canada, allow a great deal of local or provisional discretion in determining what kind of reclamation is required as part of a mine plan. At the other extreme are the US laws with rigid specific national standards defined in the legislation itself. Common elements found in many laws include requirements for separate handling of topsoil and overburden, restoration of land to its previous contour (found in the US and Great Britain), government oversight of reclaimed land to ensure that sustainable vegetation is established, and posting of a bond or other financial security prior to disturbance.

In the US, mining companies must post a bond equal in value to the cost of reclamation activities regardless of the ownership status of the land. The minimum bond is 10 000 US$ per hectare of disturbance, but the exact amount of the bond is determined from a national handbook. Bonds of 25 000 US$/hectare of disturbance may be required.

Companies provide for bonding in four ways. Large corporations are allowed to selfbond, essentially allowing a government lien against the material and financial assets of the corporation. No money changes hands, but a contingent liability is created on the books of the corporation. Smaller operators may place stocks, cash, or other financially negotiable instruments in the hands of regulators to be held until reclamation is complete. Placing stocks or cash with regulators forces the mining operator to commit the entire cost of reclamation up front, requiring assets far beyond the capability of most small operators, and having a negative effect on the net present value of potential cash flows (a large fixed sum of money experiences no growth for 10 years or more). Alternatively, operators may buy an insurance policy for the reclamation work. The cost is less, and the insurance company takes the contingent liability. The cost of buying insurance is non-refundable, and many insurance companies will no longer underwrite the risk because of the high cost of reclaiming a site after a mining company default and because of the narrow profit margins common in small coal companies. This leaves small operators to find bonds through bonding companies, financial institutions, or any other costly means available. The lack of availability of bonds at any price, or only at exploitative and unrealistic prices has caused some small operators to leave the coal business.

Securities posted for reclamation bonding are returned in three phases in the US. The first part of the bond is returned when the pit is backfilled, regraded, and drainage is controlled. This work can often be a part of the mining sequence. The second part of the bond is released when vegetation is initially established. The last part of the bond is released after successful revegetation and productivity has been maintained for a period of 5 to 10 years. The law rigidly defines the density and productivity of vegetation relative to pre-mining conditions, effectively requiring that yield and cover be statistically equal to or above that existing in similar unmined areas. There has been a tendency for regulators to be reluctant to give operators final bond release, since there is little recourse left against the operator should vegetation fail after final bond release. The result in some cases has been to continue oversight of vegetation success on reclaimed mine lands indefinitely. Even the legislatively prescribed oversight period for the establishment of vegetation is quite long compared to other parts of the world where a more typical time is 3 to 5 years.

Choice of Post-Mining Land Use: Aside from regulatory considerations, the type of land ownership is often a significant factor. Land leased from a farmer would often be reclaimed for agricultural use, while government held land in recent years has often been used for parks, recreation, or wildlife habitat. Surrounding land use should be considered. Until recently, land was most often reclaimed either to its former use, or the predominant land use in the immediate area. Lands near the spreading fringes of suburbs may be reclaimed for industrial sites or homes, country clubs and golf courses. Lands in the vista of wilderness parks and preserves would be reclaimed as wilderness. More recently there have been cases of land being reclaimed to enhance the biological and environmental diversity of an area, such as when reclaiming lands in the US Midwest grain belt as prairie or wetlands. Location and accessibility also have a role. In one case, land with good road access near the city of Ístanbul, Turkey, was developed as a park for picnicking and fishing. Size and shape of the land tract to be reclaimed should be considered. Small irregular 20-hectare tracts would be more suitable to reclaim to the same state as surrounding lands, or as a park. A tract of 10 square kilometres could, in many cases, support a totally different land use than other surrounding lands. Characteristics of the human population should also be considered. Land near areas of rapid human population growth may be engulfed by urbanisation or may be reclaimed as parks to make a more pleasant setting for residents. Age and income or cultural values of the population may be important. A young, wealthy, urban population may put a high value on open undeveloped lands for hiking or hunting, while an older population might prefer automobile access, short trails, fishing and golf courses. An impoverished and struggling population may have little time for recreation and prefer pastureland for livestock or fields to grow crops.

Topographic relief influences the type of final grade that can be achieved, which in turn influences the type of plant life that may be suitable and the type of equipment that may be used to establish it. Mechanical tree planters would be unstable on steep slopes, and hand-planting techniques would be required. Climatic factors such as the growing season, range of temperatures, and annual precipitation limit choices of suitable plant species. Even such micro climate factors as exposure may cause different plants to be suitable for north and south facing slopes or harsh and windy ridge lines. Soils may have textures, nutrients, or pH characteristics that favour one plant species or another, or provide suitable or unsuitable support for the foundations of buildings. The importance of different characteristics of the site environment will vary with the use being made of the land. Whatever the land use chosen, successful reclamation is usually marked by stable slopes, limited erosion, clean water, non-dusty air, productive cover of selected plant species, and perhaps wildlife.

Slope Stability: Material properties, the presence and flow of water, and the grading of the final landscape determine slope stability. When the surrounding topography is relatively flat, site grading to achieve stable slopes and compatible landscape is usually not a problem. In more mountainous terrain, where the surrounding natural slopes may not be stable, the task is more difficult. Usually final site grading involves compromises between exposed highwalls and valley fills or special engineering techniques such as water diversion, special slope drainage, keying artificial slopes into the bedrock, and surface terracing. Steep grades of necessity have more limited options as to what types of vegetation may be planted.

Erosion Control: Limiting water erosion or dust blowing in the wind is best achieved by limiting the steepness of slopes (10 degrees or less is desirable, but not always compatible with surrounding topography). Another useful technique is creating a rolling or terraced topography where slope lengths and the potential for water to pick up momentum and erode gullies is minimised. Creation of a moderately rough, furrowed and porous surface tends to promote infiltration, rather than run-off of water, however, such factors as rainfall or soil grain size influence the effectiveness and desirability of this technique. Geotextile fabrics, coarse gravel coverings, and even chemical sealants have been used to stabilise slopes over the short term. Such cover, however, is not usually suitable for final reclamation. Silt fences in drainage ditches, staked hay bails along roadsides, and sediment ponds have been used to limit the distance travelled by eroding sediments and to maintain high downstream water quality. Establishing good vegetative cover will do much to prevent loss of fine soil particles to wind or water.

Where mining takes place in areas of free blowing sand or heavy natural badlands erosion (badlands are dry barren sections of land where rapid erosion has carved unusual shapes and rough terrain into the soils and soft rocks), there may be serious debate as to what constitutes good reclamation practice. The US has had cases where the plans of mining companies and environmental interests to return mined land to a badlands wilderness condition have conflicted directly with water quality regulations written to preserve water quality in non-badlands environments.

Clean Water: Control of erosion and sediment loads is usually a big part of maintaining clean water. Other issues such as salty, acidic, alkaline, or heavy-metals- rich drainage constitute problems at other sites. Overburden chemistry problems with salty, acidic, or alkaline drainage can be avoided at many mine sites by sequencing overburden handling to promote burial of the objectionable material near the bottom of the post-mining stratigraphic sequence. Mill tailings or coal preparation slurry ponds and coarse refuse piles (GOB) seem more likely to have long-term acid and heavy metals rich drainage. Some of the most costly problems could have been avoided by good hydrologic studies before plant siting so that ponds would not be situated over major fractures penetrating into aquifers or over buried bedrock valleys.

Suppression of acidic, heavy-metals-rich, drainage after it has begun is not always possible with the current state of the art. The conventional view in the US is to avoid contact of water with acid producing spoils and tailings. Elaborate drainage diversions, building of impermeable barrier walls or artificial cap layers have been tried. The concept should in theory work, since water leaching and transport reactions cannot occur without water. Two field scale problems have hampered the reduction in acid mine drainage by avoiding water contact. First, acid and metals-rich material may be non- homogeneously distributed. Second, groundwater does not travel in uniform flow nets through uniformly porous material, as specified in large-scale groundwater flow models. Instead, water travels locally in fractures and channels. The result in many cases is that water gets into even the best sealed GOBs and produces acid seeps. Location of a particular acid forming pocket or a local fracture flow path only a few centimetres wide can be almost impossible. Most currently available geophysical techniques are far short of the resolution needed to follow such flow paths at sites even as small as a few hectares.

Another approach for reduction of acid drainage problems may be to mix alkaline forming material into the tails, spoils or GOBs. A special application of this technique is the Alkaline Recharge concept. Many heavy metals are mobile only at low pH. Metal sulphides usually require an oxidant to promote breakdown and leaching. The partial pressure of oxygen in the earth's atmosphere is low enough that water will usually not carry enough oxygen to promote serious leaching problems. Ferric ion is usually the main oxidant in cases of serious metals-rich acid mine drainage. Ferric ion is soluble in quantities needed for significant leaching only below a pH of about 4.5. Thus, promotion of alkalinity in spoil piles, or carrying alkalinity into GOBs with the infiltrating water should stop acid mine drainage. The concept of alkaline admixture, or alkaline recharge, is not to neutralise acid, but to prevent it from forming in the first place. Alkaline forming materials are often evaluated by their calcium carbonate equivalent (CCE) value, that is by their stoichiometric acid neutralising potential per unit weight relative to pure calcium carbonate. The two main problems limiting the success of these alkaline methods are nonhomogeneity and leaching kinetics. Alkalinity, either admixed with the spoil or carried by seepage, is rarely present in the exact concentration to match local highs and lows in acid forming potential. Further, the reaction kinetics for acid forming reactions are usually faster than the reaction kinetics to mobilise alkalinity, thus allowing acid formation to run-away under the right conditions.

The usual technique of last resort for acid and heavy metals control is direct water treatment. Several US mining operations have found that water quality regulations may require them to treat mine drainage at a cost of millions of dollars each year, forever. The ability of wetlands systems to filter heavy metals and neutralise acidity naturally is gaining popularity.

Establishing Vegetation: The establishment of a good vegetative cover is controlled by soil chemistry and nutrients, soil texture, structure and compaction, germination and growth environment for seedlings, and the availability of water and drainage. Providing a good rooting medium or seedlings is the key to success. Choosing species capable of growth on the available material is helpful, but providing an original topsoil material at the surface will usually allow a much wider range of reclamation options and more successful reclamation.

At most sites, the topsoil is an irreplaceable resource as far as the geologically short time horizon of human reclamation activity is concerned. Failure to salvage topsoil ahead of mining operations will almost always limit the success of reclamation. A typical soil profile consists of four layers. The top layer, or O horizon, consists of decomposing organic material; the A horizon consists of inorganic soil material and organic material; the B horizon consists of mostly inorganic soil material and the bottom; the C horizon, consists of weathered and decomposing rock, which may grade gradually or abruptly into the bedrock. The term topsoil may refer only to the O and A horizons. Topsoil has not only a texture, but a porosity and structure built over time by both physical and biological processes. Increasingly, soil is recognised as a living miniature ecosystem, rather than a bulk material. Earthworms, bacteria and fungi and a diversity of positively interacting plant species make up this self renewing, balanced community. Plowing, fertilising, and even textural mixing of organically dead GOBs or ground rock almost never provide the self-sustaining successful plant communities that would be possible had the topsoil been preserved. Addition of organic material and inoculation with bacterial and earthworm cultures may be helpful, but can easily take 10, 20, or more years to develop the same level of activity in a natural soil.

At some sites, the O and A horizon may be almost absent and the B horizon only a few centimetres thick. At other sites, the topsoil material may have chemical characteristics adverse to the re- establishment of vegetation. Some mine sites may have already mishandled and lost available topsoil resources. In other areas, special handling of topsoil may not be required, or may not be within the budgetary constraints of the mining operation. In these cases, substitute topsoil is often the only option. Several guidelines can be given to make this procedure as successful as possible. Materials for topsoil can be selected from the various overburden layers. The best topsoil may be created from a mixture of overburden materials. For establishment of a rich blanket of vegetation, a loam soil (40% sand, 40% silt, 20% clay) or sandy loam (60% Band, 30°70 silt, 10% clay) or some similar combination in this range is usually best. A soil too rich in sand and deficient in fines will allow good water infiltration but lack the water retention needed by many plant species. Wind blown sand may shear off small seedlings at the base of the stem. A soil too rich in clay will probably have excessive run-off, poor drainage characteristics, excessive compaction, and strong resistance to root penetration.

Good topsoil will usually have a pH around 6 or 7, and seldom below 3.5. It will have a sodium adsorption ratio (SAR) below 4, and a low cation exchange capacity. Dark coloured material, such as some weathered shales from coal overburden, may adsorb solar energy and build up temperatures too not for the growth of most plant seedlings. Of course, placement of toxic (high SAR, salty, or containing excessive growth inhibiting elements such as excess copper or boron) or acid forming materials at the surface of the post-mining stratigraphy should be avoided, or at least capped with more suitable material where it cannot be avoided.

Topsoil, or substitute topsoil handling must consider the problem of soil compaction. A good soil not only has a suitable loam-like structure, but sufficient and properly distributed pore space to collect and retain water droplets. Multiple passes by heavy rubber tired equipment tends to compact the soil structure and close and disconnect the pore spaces. Soaking, and puddling of water that accompanies such poor infiltration and drainage characteristics tends to further compact the soil. A compacted soil will lack the water retention capabilities of undisturbed soil, making plants growing on the soil more vulnerable to draught. Since compaction is normally worse below the immediate topsoil horizon (often around 33 cm), and since roots will have more difficulty penetrating the compaction zone, soil compaction encourages shallow rooting of plants, further aggravating the problem of draught resistance.

Many overburden materials bulk significantly on initial handling, but then settle and recompact over a few months after final placement. In the Midwestern US, overburden swelling of 30 to 35% on initial handling, with an in-place, post-mining swell of 20 to 25% after one year, would not be unusual. Failure to differentiate between initial swell and shortterm, in-place, post-mining compacted swell can cause operators to select the wrong capacity when sizing mining equipment and cause problems with non-draining depressions forming after or during reclamation. Such depressions collect and the soil may compact. Regrading to establish drainage may require passage of heavy equipment over reclaimed areas creating additional compaction problems.

The best solution to the problem of soil compaction is to avoid it in the first place. Handling and placement of overburden materials should achieve modest compaction, avoid size segregation, and provide more uniform post-mining in-place density. Proper handling and allowing some time for settlement before replacing topsoil will reduce problems with depression formation. Some countries, such as the US, require strip mine reclamation to follow disturbance by only a few months. In some cases such well-intentioned restrictions can create problems with depressions and soil compaction.

Avoiding rubber tired traffic over the reclamation area and minimising excessive passes by heavy equipment in general, even for regrading, will aid in reducing soil compaction. There is some evidence that stringent US reclamation laws requiring rigid restoration to original contour, or excessive separation of thin soil horizons, may be causing significant problems with soil compaction due to the number of equipment passes required to achieve compliance. The result may be permanent dependence on irrigation, and reduced success in establishment of trees, which require deep rooting.

Where compaction has occurred, the best alternative appears to be deep tillage with implements penetrating and loosening up to the top meter of soil. Under some Midwestern US conditions deep tillage in only one direction may still leave an excessively compact zone around 50 cm into the soil. Tillage in two directions at 90 degrees to each other may help to alleviate this problem but involves significant additional cost.

Many of the preparations for successful reclamation can be integrated into the mining sequence with much less impact on final cost than would result if reclamation were an afterthought. Particularly, mining sequences can be adjusted so that post-mining stratigraphic sequences are amenable to revegetation, and regrading and rehandling of overburden is minimised. Pre-mining topography, surface mining method, and final reclamation plans will influence the operations sequence and equipment selection for integration of reclamation into the overall mine plan. Area strip mines, contour strip mines, backfilled open pits, terrace pit mines, and surface effects from underground room and pillar or longwall mines all have unique reclamation problems and opportunities.

Contour Mining: Contour mining is most often used on near horizontal coal deposits in mountainous terrain. Mines are generally smaller in size, have lives of less than 5 years, and advance comparatively rapidly, around the contour, along an advance front of about 100 to 200 meters width. Lack of space for placement of excess spoils, highwall instability induced by auguring back into the seams beyond the stripping limits, and the re-establishing of stable slopes without leaving exposed cliffs are special problems for this kind of mining operation.

Topsoil should be recovered wherever possible, and is usually the first step in the stripping sequence. Scrapers, dozers, front-end-loaders (FEL) and trucks are the usual equipment of choice. Scrapers may directly, or with dozer assistance, pick-up the topsoil and carry it across the pit for placement on top of the spoils on the other side. The scraper traffic may either cross the pit directly, or where traffic congestion is a consideration, drive along a separate road developed on the highwall or just below the cut.

Another alternative for topsoil removal is to blade the topsoil off with a dozer trapping for a FEL. The FEL can then load the soil into a truck for haulage to the reclamation area situated on the other side of the pit. It is generally preferable not to store the topsoil. Placement of topsoil in storage piles will involve later rehandling of material, and may require separate stripping and recovery of topsoil from the storage area. Also, topsoil stored in large piles tends to lose biological activity, soil structure, and fresh organic material from material stored near the bottom. Excessive handling promotes compaction and destroys soil structure.

Equipment stability on steep slopes or the lack of quality topsoil are special problems that may be encountered in mountainous areas. Where these problems are found, substitute topsoil may be required.

Contour haulback is a good example of integration of sound reclamation handling into the mining sequence. Rather than overturning and dumping overburden down the hillside into unstable banks and leaving the highwall exposed, this method places material in a designed stratigraphic sequence against the highwall of the old pit. Contour haulback operations frequently replace the overburden strata in very nearly the same sequence as it was removed. The most notable exceptions are cases where individual overburden layers are too thin for separate handling, or where a toxic layer is buried near the bottom of the sequence to reduce leaching and adverse effects on plants.

Where overburden layers are soft or thin, scrapers may be used for overburden removal. More commonly, layers are moved with loading equipment and trucks. Truck-shovel operations usually cannot handle as thin a layer as can be handled by scrapers. Using dozers to blade material down to the loader may allow selective removal of layers almost as thin as can be removed by scrapers. If thicker layers must be taken, or if separate handling of topsoil and the various soil horizons is not possible, material placed at the front of the truck will tend to come out on top when the truck load is dumped. In choosing loading equipment, FELS offer mobility, low capital cost, and can work with dozers trapping material. Hydraulic excavators offer more power for hard rock layers and can be used to selectively pick out toxic materials or substitute topsoil materials from the overburden removal face. The ability to selectively remove layers from the face allows for separate handling. Large cable shovels are generally not suitable for contour mining operations because the fixed digging stroke will mix all materials on the digging face. A large cable shovel will usually provide more overburden handling capacity than normal contour stripping ratios and production rates require. The surplus capacity often results in high ownership costs per cubic meter of overburden.

As the overburden stratigraphy is rebuilt on the opposite end of the pit, a beam of coal is left around the outside edge of the cut to help key in the slope. Drainage diversion along the buried highwall, or placement of drains at the base of the fill, is sometimes practised to increase stability against water problems.

Contour haulback operations usually require placement of some material at a site other than the previous cut. This situation obviously occurs with the opening cut but also occurs due to the swell of overburden. Surplus overburden is most appropriately placed in a valley fill as close to the mining area as practical. Placement of material either above the highwall, or below the cut will usually result in an unstable slope. Placement of material in a valley fi11 near the head of a valley will minimise the extent of the drainage that may destabilise the fill. Removal of topsoil from under the area to be filled, creating diversions for water around the fill or drainage through the fill and keying into bedrock, will improve the stability of valley fills. Replacement of topsoil over the top of the valley fill, or use of topsoil substitute material will aid in establishing a vegetative cover over the fill.

Backfilled Open Pits: Some open pits are designed to be backfilled with overburden material from other pits or other parts of the same pit. Open pits, either partially or fully backfilled, are most often used on steeply dipping coal seams. Such mines often use trucks and shovels for overburden materials movement. Pits are usually smaller and less than 150 meters deep. Recovery of topsoil ahead of mining operations is usually desirable. Scrapers are often chosen for topsoil removal. Immediate placement of topsoil in an area being reclaimed is desirable, since it negates the need for storage and rehandling. Caution with soil compaction is warranted. A better choice may be removal of topsoil with a dozer trapping for a FEL. The material could then be hauled to the new site by truck, dumped at the periphery, and graded into place by a low ground hearing pressure (LGP) dozer. Still another alternative may be transport of topsoil by conveyor and approximate placement by a stacker, with final grading by a LGP dozer. The conveyor hopper could be loaded by truck dump, FEL, or even belly dumps from a scraper used to remove the topsoil.

Benches developed for overburden removal could be made to correspond to the existing stratigraphic sequence, especially in layers that require deep burial or have special value as substitute topsoil. Another alternative would be use of a hydraulic excavator for truck loading. The two piece boom, pivoting bucket, and powerful digging forces of a hydraulic excavator allow the machine to pick out individual layers from benches that do not correspond in height and position to the pre-mining stratigraphic sequence.

Terrace Pit and Area Strip Mining: Area strip mining and terrace pit mining are most frequently used on large, relatively flat-lying coal deposits in less mountainous terrain. Large dedicated overburden movers such as draglines and bucketwheel excavators are used to uncover the coal. These overburden movers lack the ability to selectively handle individual rock layers in the overburden and result in a mixture of material on the spoil side of the pit. Dilution of toxic layers, rather than deep burial must be an option. Recovery of layers for substitute topsoil is not possible. Where separate handling is required, a bench must be left and worked with separate equipment. Scrapers and dozers are often used to push a toxic layer over the edge of the highwall to the bottom of the pit for burial. Location of toxic layers in the middle of an interval that could be taken with a dragline, will often destroy the economics and technical feasibility of dragline use. The reasons are that draglines lack the ability to work small benches and that their high purchase cost must handle large volumes of material to be economically attractive. Removal of layers above the toxic material using benches excavated by truck and shovel, with the dragline working the interval below the toxic layer is a possibility. This arrangement of truck-shovel benches advancing ahead of the dragline operations is called Terrace Pit Mining and is also used when the overburden becomes too deep for removal by a dragline clone. A toxic layer directly above the coal seam or as a parting between coal seams usually does not interfere with dragline or bucketwheel excavator operations.

Where topsoil resources are to be preserved, they must be recovered ahead of mining operations. Scrapers are popular because of their ability to remove thin layers and haul them directly to the reclamation area on the other side of the pit. Placement of soil in thin lifts with careful grading by dozers and road graders has provided excellent separation of soil horizons and restoration to the original contour but has created serious compaction problems. Scrapers also distort the soil structure so that the direction of easiest root penetration is horizontal, thus encouraging plants to develop shallow, horizontally growing roots. Truck and FEL removal of topsoil with spreading and placement of truck-dumped material by LGP dozers is now often advocated. US operations differ from those in many parts of the world in using mobile rubber tired heavy equipment. In reclamation, this offers the advantage of selectively handling overburden and topsoil layers. It has the disadvantage of increased soil compaction. In Germany, topsoil is replaced over mined out lignite reserves by slurring the topsoil into place. The method avoids compaction by heavy equipment, but suffers from the effects of water saturation. Bucketwheel excavators with conveyor haulage, or even use of hoppers with conveyor haulage instead of trucks, are more common outside the US. Initial placement by conveyor with only modest grading by heavy equipment reduces soil compaction but is often less selective and less flexible and may cause materials to segregate by size.

Overburden removal equipment like draglines and bucketwheel excavators tend to produce spoil piles in rows of ridges. These ridges must be leveled prior to placement of topsoil. Levelling can be done by dragline rehandle on the spoil side, trucks dumping overburden between spoil peaks, and dozers pushing spoil peaks into the lows between ridges. Dozers working in such applications are equipped with V and sidecasting blades. The dozer first advances down the length of the ridgeline with the V shaped blade, sidecasting the peak of the spoil into the lows on either side. A sidecast blade inclined only to one side is then used to widen the flat area on top of the ridge by sidecasting from one side at a time. This technique allows the dozer to work more productively on level terrain without backing up.

While the direct cost of dragline operations for spoiling overburden material is frequently the lowest, the cost of rehandling on the spoil side to level for reclamation can be very high. Bucketwheel excavators can be coupled with conveyors and stackers to spread material on the spoil side so that much less regrading is required. Bucketwheels can only be used in softer overburden. Narrowing of dragline pits and reducing swing angles can allow draglines to better disperse material on the spoil side and can also reduce the height of spoil ridges and percentage of rehandle. However, narrower pits can limit the type of coal handling equipment that can be used in the bottom of the pit and reduce blending options. Use of trucks and shovels to bench ahead of draglines (Terrace Pit Mining) is growing because large trucks and shovels can bring material to its final resting place for costs not much higher than dragline spoiling and dozer rehandling in wide pits. The option of filling between spoil peaks with trucked overburden also reduces the need to rehandle the dragline material, thus providing savings to offset the increased cost of trucking. Sometimes bucketwheel excavators removing soft overburden ahead of dragline operations can achieve a similar advantage.

A special case of area strip mining is Mountaintop Removal. This method is used on the same type of deposit that is frequently contour mined. Combinations of trucks and loaders with draglines remove an entire mountaintop above the coal seam. Pit configuration and equipment operations can be arranged either like backfilled open pits, terrace pits, or area strip mines. The type of equipment and arrangement used will influence how reclamation is integrated into the operation. Guidelines given in backfilled open pits, and previously for terrace pits and area strip mines, can be applied. Mountaintop Removal usually involves several special problems. In the US, restoration to original contour is required by regulation, and a special waiver is required for this type of operation. In Mountaintop Removal, at least part of the overburden must be placed in large valley fills. Mountaintop Removal also has been found to require substitute topsoil where mountain soils are thin to almost non-existent.

Surface Effects of Underground Operations: It is a mistake to believe that underground mining of coal negates the need for surface reclamation. Longwall and Room and Pillar operations create subsidence troughs and pits. In prime farmland, such as the US Midwest, troughs disrupt drainage, causing ponding and soil compaction in fields. In arid western US deserts, subsidence can disrupt cliffs and nesting grounds for raptures. In the eastern US, open mine portals become a source of acid mine drainage. In addition to techniques for acid mine drainage control, mines are sometimes sealed or allowed to flood to cut-off contact with oxygen needed for microbial regeneration of ferric ion. New research is finding ways to predict mine subsidence profiles in advance of mining. Use of these techniques to evaluate post-mining topography can limit the formation of non-draining depressions. Where such depressions form, regrading and ditching may be required. Care should be taken to avoid equipment with high ground bearing pressure and to avoid working on ground that is still soaked or ponded with water, since this will create soil compaction problems. Deep tillage may be required in some cases to break-up the compaction caused by ponding and operation of farm machinery.

Vast areas of land have been left scarred by ill-planned mining operations. Less stringent regulations in some countries continue to allow diminution of post-mining land potential. While such sites have unique problems, one reclamation project in Turkey may furnish some guidance for modest and practical reclamation efforts in some parts of the world. The site was an abandoned area strip mine for lignite. Overburden had been scattered irregularly and mixed. Topsoil was usually located at the bottom of the post-mining stratigraphy, except where it had squeezed up between the barren overburden. Erosion carried spoils into the river basin below, clogging the streams and burying the meadows and fields that had existed previously. Only small remnants of the oak forest that had once covered the area remained.

The area is gently inclined toward the Black Sea. It was decided to reclaim the state owned land for forests, lakes and meadows for recreational use by residents of Istanbul. Maps and cross-sections of the land were prepared. Overburden was sampled, drilled, and tested to locate material that could be used for topsoil over toxic spoils and to ensure that material movement did not uncover further toxic spoils. Minimisation of materials rehandling was an important criterion. Stabilising slopes and controlling erosion were also key concerns.

Firstly the post-mining landscape was laid out and planned, detailed materials handling plans were then prepared, and lakes were located in depressions. Steep slopes were generally terraced rather than completely regraded. Grading of terraces and other land was planned to allow use of mechanical tree planters. Topsoil or substitute topsoil was used to bury some of the most toxic materials to a depth of 80 cm. Since all the toxic material could not be buried, some of the salty and acid forming material was treated with time to obtain nearly neutral pH.

Trees were planted on the reclamation site. Deciduous trees were planted along the shores of the lakes, and rapidly growing deciduous trees were planted along the roadside. The remaining areas were planted with conifers, intermingled with rapidly growing deciduous trees. The deciduous trees helped prevent the spread of fire through the conifers and also provided a rapid source of organic material to begin building a topsoil community. The river valley was set up as a tree farm to grow seedlings for planting on site. To aid trees in becoming established in the abandoned mine area, they were planted in holes in the spoil that were filled with topsoil. The area around the trees was hoed several times a year to prevent cracking and baking of the spoil and promote water infiltration. Staked brush lines were set up for immediate erosion control. After just two years, some of the faster growing tree species had reached heights of up to 4.5 meters. Carp in the lake weighed as much as two kilograms after the first season.

The example contrasts with US reclamation efforts, which have emphasised more the establishment of grasses, sometimes to such an extent, that it has been suggested that the grasses may prevent the growth of trees.

For most types of coal mining operations, there can be little doubt that reclamation of the land following mining causes an added cost. It should be pointed out, however, that loss of use may carry costs that in human and national heritage terms may defy financial quantification. The exact cost of any reclamation will be site specific, but the following example may give some guidance. The example is an area strip mine 2 kilometres in length, advancing over a distance of 5 kilometres, mining through 30 meters of overburden to reach a single coal seam 2 meters thick. A, B, and C soil horizons are 0.3, 1, and 5 meters thick, respectively. In cost illustration 1, the deposit is mined by dragline without reclamation. In cost illustration 2, attempts are made to reclaim the devastated landscape generated in illustration 1 as forest. The approach is similar to that described in previous sections of this chapter. In cost illustration 3, the mine is developed by dragline, but reclamation practices are incorporated into the mining sequence. Topsoil and subsoil recovery by scraper is practised ahead of dragline operations, and spoil side ridges are levelled by dozer ahead of soil replacement. In cost illustration 4, trucks and shovels bench ahead of the dragline, with trucks dumping between the dragline spoil ridges. Topsoil is recovered ahead of benching operations using dozers trapping for FELS loading trucks. Topsoil is graded into place by LGP dozers.

Several observations can be made about the reclamation costs in these illustrations. The added cost of reclamation represented a 15 to 22% increase in the direct operating cost of coal production compared to mining with no restoration of the land. The percentage is significant, but the cost of coal production in the illustration is low and does not include any coal preparation or transport charges. The A and B horizons in the example were comparatively thick and in some cases only the A horizon would be handled as topsoil. Further, additional costs from adaptation of materials handling procedures to accommodate reclamation were included as a reclamation cost, even where the operation was essential to uncover the coal. In Germany, where costs of production are higher, reclamation represents about 10% of total costs.

A second significant observation is that the cost of reclaiming land devastated by careless mining can be higher than mining in an environmentally sound manner in the first place. Of course just planting a few trees and installing a few silt fences would be less costly than the attempt to create a semi-productive forest as shown in illustration 2. The reclamation in illustration 2 used the roots of trees to break-up the spoil over the long term, and used mulches, organic supplements, lime, and fertiliser to try to create a soil in which the trees could grow initially. It will probably take conservatively 10 years, and more likely 20 or 30 years of oversight and fertilisation to create a biological topsoil community at the site that even resembles the community that existed prior to mining. If the cost of oversight management in illustration 2 is extended from 5 years to 10, 20, or 30 years, the cost of reclamation will vastly exceed the cost of mining responsibly in the first place. Illustration 2 includes no charges for acid seep management and treatment. The site will almost surely have significant problems of this type. Finally the site in illustration 2 can only be reclaimed as a less than healthy forest during the lifetime of the next few generations. The option of making the site in illustration 2 into fertile cropland or pasture does not exist. In illustration 3 and 4, the site could be reclaimed for almost any desired use, including productive cropland. It is unlikely that the immediate sales price of the reclaimed mined land would pay the reclamation costs in the illustrations. It is also unlikely that a society can be certain that it will not need lands devastated by mining without reclamation for the 500 or 600 years which may be required for natural recovery of the site. Where total cost to a society is considered, reclamation during mining is usually the financially sound choice.

Efforts in recent years have been directed toward the use of recycled material in reclamation. Sewage sludge has been used to add organic material to substitute topsoil. Salt content of the sludge can be a problem in some cases, but heavy metals and man made organics have not accumulated in the food chain as feared. Plants generally do not take up enough heavy metals to create problems in the food chain.