The Constancia tailings facility, located in the Peruvian Andes, was designed to store more than 450 million tonnes of copper tailings in an area of relatively high seismicity and seasonally high rainfall. The tailings dam, currently more than 100 meters high, is constructed of compacted rockfill sourced from glacial outwash, quarried sandstone, and open-pit waste rock, and will ultimately be raised to a height greater than 170 meters. The dam comprises an initial downstream-method rockfill embankment with sloping upstream core and chimney drain, with subsequent conversion to a centerline-method, supported by an upstream rockfill platform to provide support to the vertical section of core and filter/drain zones. This paper provides a summary of the design analyses and describes observations made during construction and operation. Site-specific deterministic and probabilistic seismic hazard analyses, seep-age, slope stability, and deformation analyses performed to predict the long-term engineering behavior of the dam and impounded tailings are described.
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