TECHNOLOGICAL AND ENVIRONMENTAL ASPECTS OF ASSESSMENT OF A COMBINATION OF DIFFERENT MINING METHODS USED IN ESTONIAN OIL SHALE INDUSTRY

Oil shales used in Estonian power plants to generate electricity and in oil production are of different quality. Different excavation methods in use and accompanying development processes are accompanied by various emissions that call pollute water and air. However, generation of waste as well as impact on land use are of greater concern than emissions into the water and atmosphere. Life Cycle Assessment (LCA) has proved to be one of the most attractive approaches to characterize sustainability of mining industry, as several environmental and economic indicators are used to assess its performance. The methodology enables to choose the best available environmentally friendly technology. As shown by investigations, the mining processes exerts smaller effect on acidification, terrestrial eutrophication and ecotoxicity than production of auxiliary materials and transportation of oil shale to customers. Other impacts considered and discussed are ground surface subsidence, land use for deposited wastes and mine water pollution. Assessment of the impact caused by a combination of different mining processes gives the opportunity to find a better way for planning new mines in accordance with environment protection measures in the area of the Estonia oil shale deposit.