Surface mining as at present involves removal of vast quantities of overburden which has to be dumped and creates problems because of its effect on environment. A coordinated environmental protection and reclamation programme is essential for the large opencast mines and has to be implemented sequentially. The establishment of vigorous, self-sustaining plant community is the key component of eco-effective reclamation. Effective reclamation implies economically feasible procedure that control erosion, sedimentation and the off-site movement of potentially toxic materials, while improving the appearance of the landscape and allowing the reclaimed dump to be returned to productive use. An account is presented here of the range of some modern techniques available for reclamation of spoil heaps and a case study of two major Indian opencast coal mines about reclamation practices have also been discussed.
Surface mining involves the removal of overburden to exploit underlying deposits. With rapid advancement in the field of opencast mining technology and beneficiation techniques, it is possible to exploit deeper and submarginal grade ores which was not possible in the past. Since the qualities of waste have increased, its disposal has created a problem because of its irretrievable damage to the environment. Waste dump should be properly reclaimed and planning (or it, is a multi-disciplinary task Brave, 1987; Prabhakara & Kamaraj, 1976). Mine planning and reclamation planning should go together, and surrounding environment can be improved by adopting reclamation technique or programme (Rao & Balakrishnan, 1976).
Land is an important natural resource. Waste dump situated on land should be reclaimed to: a) reduce the impact on general environment (Blelloch,1983; Ghosh et al. 1984; Johnson & Bradshaw) 1978); b) put the dump for some productive use (Norton, 1990); c) avoid sudden slide of dumps when saturated with rain water (Akers & Muter, 1974); d) maintain aesthetic beauty (Ghosh, 1991); e) help in the process of ecosystem development Kleiman & Layton,1979; Larsen & Vimmer, 1990); f) rehabilitation of mine spoils (Chatterjee, 1988). Some of the six main uses of reclaimed land are as follows, and depend on natural and socio-economic factors of the locality: a) agriculture (arable and orchards, meadows or grazing land); b) forestry (commercial or non commercial forests); c) recreation (recreation zones, parks, or public open space); d) water use (fishing, swimming, boating and yachting); e) construction (sites for light industry, houses, service purposes); f) wildlife habitats (wilderness areas).
A co-ordinated environmental protection and reclamation programme is essential for developing cost effective environmental control programme (Cull & Depuit, 1979). Reclamation is a fairly complex process because it requires several widely different types of expertise to plan and manage. Fig. 1 shows a complete reclamation procedure. 3.1 Preservation of top soil The top soil of any area is the best media for revegetating and hence it should be seperately preserved. The basic idea is to segregate the top soil from the spoil material so that the top soil may be later utilized during reclamation. Top soil should be considered as an ecosystem and not simply a physical resource (Jeffrey et al., 1974). 3.2 Selection of disposal site Dumping of mining waste should be done in such areas which are (a) non productive, (b) does not contribute much to the runoff of the catchment and (c) does not have any potential aquifer in the area,(welch, 1990). 3.3 Surface preparation On completion of dumping of spoil preparation of the surface will depend on whether any agriculture or forestry is intended or possible.