Methodological proposal to predict impacts arising from accidents with tailings dams

The tailings dam failures is a matter of concern due to the high damage potential associated, requiring an assessment of forecast impacts that allows better characterization of downstream area, and that data collection is performed by regulatory agencies and not by the entrepreneurs. This work aimed to propose a classification of impacts resulting from hypothetical tailings dams failure, based on the damage assessment adopted by dam safety legislation in Brazil. For that, a table of criteria and subcriteria was elaborated with the parameters that influence the determination of the resulting impacts, which were hierarchized through the application of the Analytic Hierarchy Process (AHP), proposed by Saaty (1991). To determine the weights of each impact, the Ad-Hoc technique was used through the dynamics of brainstorming, with professionals who made judgments from parity comparisons of the determined criteria. Human occupation in the downstream area, as noted in the legislation, presented the greatest weight. The volume of the reservoir and the impacts on the socioeconomic environment presented lower weights to the impacts in the physical and biotic environments, in contrast with the legislation. The application of the methodology in the Quadrilatero Ferrifero dam proved the consistency of the proposed impact index (IA), indicating the fragilities of the affected area. The detailing of the downstream area allowed to identify aspects that could potentiate or amortize the impacts, such as hazardous waste, reservoir volume, and proximity to urban centers.