Evaluation of Hydraulic Conductivity of Itabirites of the Alegria Centro and Alegria Sul Open Pits, Samarco Mineração S.A., Minas Gerais State, Brazil

Itabirites in Samarco Mineração S.A.’s open mine pits in the Quadrilátero Ferrífero region, Minas Gerais State, Brazil, were hydrogeologically characterized. Itabirites, which represent the main aquifer in the region, were divided into four lithotypes based on their mineralogical composition. Statistical analysis of fracture frequency and rock quality designation were evaluated and correlated to hydraulic conductivity results. Preliminary analysis showed a highly fractured rock mass with relatively constant fracturing with depth, regardless of lithology. Field experiments were performed to determine the hydraulic conductivity and provide input data for an analysis of fracture frequency. Infiltration tests showed a median hydraulic conductivity of 1.2 × 10 −7 m/s, while packer tests indicated a median hydraulic conductivity of 9.6 × 10 −7 m/s. Fracture frequency was related to hydraulic conductivity through the cubic law. Median hydraulic conductivity values for the rock types at the mine were found to range from 1.2 × 10 −7 to 1.0 × 10 −6 m/s.