Manmade disasters and Malpasset

Recently Chris took one of the geologists from Wheaton College around the area of Courmettes  to look at the possibility of running a field course  down here. Maybe.

But we were reminded twice this week of  one part of the trip, once by the appalling and seemingly preventable inferno at Grenfell Tower and also by the fact that here in Var it has been the seventh anniversary of the severe flooding in our area where at least 27 people died .

But the Malpasset Dam failure  of December 1959 was worse than both, with a death toll of 423. It’s a sadly instructive story. The dry summers of the region and the post-war population boom made increased water storage in the area essential.  And so a dam was built across the River Reyran some seven or so kilometers upstream of Frejus. In theory, it should have been fine: a state-of-the-art, carefully engineered, reinforced concrete dam on hard metamorphic rocks. No problem. 

But someone hadn’t done their homework. Under pressure, the water slipped into an overlooked fault which ran under the dam and lubricated it. After heavy rain the dam totally collapsed in the middle of the night releasing a 40 metre high wall of water that tore down the river valley at around 70 km per  hour. The narrow cross-section of the valley channelled the flow and kept the speed up so that blocks of concrete from the dam the size of cars and trucks were tumbled along down the valley for a kilometre or more. The water raced on and when it reached Frejus, 20 minutes after the breach, the flood was still 3 metres high and wreaked enormous and deadly havoc.

In hindsight, and there has been a lot of hindsight, the cause of the failure was the coming together of a whole series of managerial and technical mistakes; each on its own minor but together contributing to an overall whole that was a disaster waiting for something to trigger it.

The dam was never rebuilt and a totally new artificial lake (Lac de Saint-Cassien) was created to replace it. Any one driving between Nice and Frejus on the autoroute drives within a kilometre of the ruins of the dam, which now lies half-forgotten  in a tranquil valley disturbed only by walkers and the curious.

But it’s open to question whether, nearly seventy years on, we have learned the lessons that Malpasset should have taught: you can pay a terrible price for carelessness in construction.

This aerial view of the dam and lake must have been taken in the mid 1950s.

To get to the site you have to go under the autoroute

Memorial at the start of the walk (in five languages)

These room-sized blocks of concrete are over 1 km from the dam

The dam as it is today. You can judge its former height by the structures at the top of the slopes on right and left.

Remains of the wall and discharge pipe

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