The Stava Tailings Dams Failure, Italy, July 1985

The collapse of a mine tailings storage facility near Stava, northern Italy, resulted in 268 deaths and very considerable damage to property. The geological setting and the history of the construction of the tailings dams are described, the more important geotechnical properties of the tailings material are presented, and the degree of stability of the dams is discussed. Possible causes of the failure are reviewed, and it is concluded that the dams were constructed with an unacceptably low factor of safety and that the circumstantial evidence supports the conclusion that the failure was triggered by a blocked decant pipe located within the tailings.