

This paper describes aspects related to the elevation process of a mining dam, named Capão da Serra, located in the city of Nova Lima/MG in Brazil. The main objective of Capão da Serra Dam is the mining sediments retention and effluent clarification from the exploration of Tamanduá Mine. The project was developed for the third and last phase of the dam elevation, with an height increase equal to 8.0 m. Since the beginning of its operation, the hydraulic system of the dam was composed by a tulip-shape spillway, complemented by a security earth spillway located on one of the sides of the dam. However, long-term efficiency of the hydraulic system was not clear, due to uncertainties regarding the expected hydraulic head at the final elevation of the dam. Since this was the last phase of the dam elevation, aspects concerning the run-off system were also taken into account with the objective of defining the most efficient, secure and long-last hydraulic system for that specific site conditions. The new spillway, placed directly over the dam earth mass, was designed to support a runoff flow equivalent to a 10,000 year return period rainfall and a high velocity free-surface flow. Geosynthetics were applied to develop primary and secondary functions concerning erosion control, soil reinforcement, drainage and filtration. Several innovations were proposed and applied during this work, concerning geosynthetics installation plan. The geometric project had to be well established to avoid perturbations on the hydraulic flow at the interface between reservoir and spillway. The geosynthetics characteristics attended all needs of this project, including durability, flexibility, easy handling and compatibility to conventional construction materials.