Glacier lake under Mont Blanc to be drained

French engineers are preparing to drain an underground lake under the Mont Blanc glacier in the Alps on Wednesday. The lake, thought to contain more than 60,000 cubic metres of water, could flood the Saint-Gervais valley.

Flickr/Richardcjones

The engineers will dig a hole in the ice and pump the water away. The valley beneath Mont Blanc is home to around 2,000 people and is a popular tourist area.

“The situation is extremely serious,” said the mayor of Saint-Gervais Jean-Marc Peillex.

Alarms were installed in the area in July to provide an early warning system. It is thought the lake below the Tête-Rousse glacier contains enough water to flood the valley in a short period of time.

“If the sirens sound the first chalets have 10 minutes to evacuate, the last 30,” Peillex added.

Teams will drill up to 50 metres through the ice to reach the water, although they are not sure what will happen once the lake is drained. Local people have been briefed on an evacuation plan.

“Today, draining it has become urgent,” said Christian Vincent, an engineer at the glacier laboratory of Grenoble, who’s in charge of the project. “The water is pressing on the surface of the glacier, this means it is under pressure.”

The only access to the area is via helicopter as there are no roads leading to the site. The area is also susceptible to avalanches making the operation risky.

Three pumps began draining on Wednesday morning and it is thought it will take one month to complete the procedure, estimated to cost 2.5 million euros.

In 1892 a pocket of water flooded the valley killing 175 people. Around 200,000 cubic metres of water travelled at a speed of about 14 metres per second down into the valley.