In the last six years Brazil has recorded at least three failure events of tailings storage facilities (TSF)which caused human deaths, all located in the state of Minas Gerais: the September 2014 rupture ofHerculano's B1 TSF in Itabirito; the November 2015 rupture of Samarco's Fundao TSF in Mariana;and the January 2019 rupture of Vale's TSF I in Brumadinho. In addition to significant environmentaldamages, the events caused a total of 292 deaths.In response to these events and aiming to reduce the risk of other failures, the Brazilian national andMinas Gerais state regulatory agencies have been developing new legislation related to the safetyand emergency management of TSF. Consequently, the owners of these facilities have been facingnew obligations. New legislation presents different definitions for what constitutes decharacterization(ie transitioning from a dam to an earthen structure that is not a dam) and closure ofthese structures. Despite the new legislation, regulatory agencies have not yet established detailedguidelines related to the de-characterization and/or closure process. Nor have they developed thetechnical criteria that should guide the closure design and agency approval of closure solutions.
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