This paper describes the behaviour of a 10 m high trial embankment built on silt gold mine tailings of Morro do Ouro Dam, Brazil. The dam is the country’s largest tailings dam having 120 m in height and 4 km in length. This trial aimed at investigating tailings strength behaviour, which field experience has already indicated to be better than predicted by in situ and laboratory tests. The embankment foundation was instrumented with piezometers, settlement plates, profiler and inclinometers. Just after placing the first 2 m embankment layer, one observed water surges, interpreted as static liquefaction taking place at low stress level. Large porepressures and displacements were recorded during construction. The embankment height was taken to 10 m, much higher than predictions based on in situ and laboratory tests. The foundation strength was also analysed.