AbstractLa Parrilla is a tungsten and tin mine located in western Spain. The tailings facility has a total capacity for 3 Mm3 and will be executed in four different phases. The main constraint for the design and construction of the tailings dam is that it has been constructed over an existing one from the 1980s. The construction activities involved removal and substitution of the old tailings from the southern portion of the facility, ground improvement with gravel columns over an area of about 10,000 m2, and construction of the dyke’s dam. This article describes the main design and construction aspects, including monitoring, until the dam’s completion in June 2019.