Classificação das barragens de contenção de rejeitos de mineração e de resíduos industriais no estado de Minas Gerais em relação ao potencial de risco

Abstract

Recent accidents involving tailings and waste dams started to turn attention to these structures, which is growing as industrial production increases. The Brazilians experience has contributed to the creation of the Dams Security National Policy. This policy has been instrumental in developing standardized criteria for each of the structural phases (life cycle) of dams. The State Environmental Foundation of Minas Gerais (FEAM) through their legal framework DN 62 (COPAN, 2002), modified in 2005 (DN 87); and in 2007 (DN 113) registers and classifies dams through height, volume, downstream human populations, installation and environmental aspects. In accordance with the potential risk of environment damage, the dams must be submitted, periodically, in new technical audit of security, being to every three years for the classified as Class I; two years for the Class II and annually for the Class III. In partnership with the FEAM, this work applied data of 124 wastes and tailings dams of Minas Gerais State, in a model of potential risk evaluation developed by Menescal et al (2001) and adapted in this research for wastes and tailings dams, in order to generate representative and functional outcomes. The model considers aspects of danger, vulnerability and strategical importance, supplying an additional tool to subsidize the decision making of the dams' management, allowing to focus in that to present more critical situation in potentialrisk and the environment damages potential. The findings of the research showed no dam was rated as very high for potential risks; 30% of the dams as Medium Alert risk was found, what it discloses the necessity to priorize the attention and intervention in these structures