33. The Val di Stava Dam

Location: Stava, Italy

Year of Fail: 1985

In one of Italy’s worst national disasters, the Val di Stava dam failed in 1985, killing 268 people, demolishing 63 buildings and destroying 8 bridges. When a pump in the upper damn began to sag, drainage became less effective. However, water continued to be pumped into the reservoir behind the dam at the same rate, increasing pressure on the upper dam’s banks. Water infiltrated the banks, liquefying the soil in the dam walls, which ultimately broke. The upper dam’s water rushed into the lower dam, which failed 30 seconds later.