Looking back to 1985: Val di Stava dam collapse – one of Italy’s worst disasters

2,000 editions ago, on July 19, 1985, one of the worst disasters in Italian history occurred.

The Val di Stava Dam, located above the village of Stava, near Tesero, collapsed after after two tailings dams gave way. As a result, 268 people were killed in less than four minutes.

When the upper dam broke, the force of water escaping it caused the lower dam to collapse. That released around 180,000 m³ of water containing mud and sand into the Rio di Stava valley below.

Thundering downhill at approximately 90 km/h (56 mph), the raging torrent ripped through the village. A total of eight bridges were demolished along the way, plus another 63 buildings. After flowing around 4.2 km (2.6 miles), the huge wall of muddy water eventually reached the Avisio River.

What did the investigations discover?

Subsequent investigations into the tragic incident discovered that the dams had been very badly maintained with a low margin of safe operation incorporated.

Due to a build up of sediment in a pipe used for draining the upper dam, it had allegedly started to buckle, causing the operation to be less effective.

This drop in sufficient drainage, coupled with the constant pumping of water into the reservoir that the dam was holding back, created immense pressure on the bank of the dam, the report detailed.

As a result, the bank’s soil started to liquefy until it finally gave way. The contents of the upper dam then entered the lower dam and only 30 seconds later the pressure caused the collapse of its wall.

For their roles in the disaster, a total of 10 people were eventually found guilty of culpable disaster and multiple manslaughter and were sent to prison in June 1992.