Details:
The Valle di Lei dam, activated in 1962, is located in Switzerland and is the hub of KHR's plants. The arch barrier has a maximum height of 138 m and a crowning length of 690 m, making it the third largest in Switzerland. The reservoir, about 8 km long and about 500 m wide on average with a maximum capacity of 197 million m3, is mainly developed in Italy on the territory of the Municipality of Piuro (SO).
For the maintenance work of the dam, especially concerning the supply pipe, the bottom and lightening drain and the supply tunnel, it was necessary to complete the emptying of the reservoir that started in November 2011. The opening of the drain began in October 2012 and the reservoir remained empty from November 2012 to April 2013. In July 2012 was installed along the roadway on the left side of the lake an inclined-piezometric DMS column, 80 m long, composed of 80 biaxial inclinometers and temperature sensors, 3 piezometers separated by thin layer packers and 1 digital compass. The column has made it possible to continuously monitor, in automatic and in real time, the phases of recessing and subsequent filling of the reservoir and is currently still in operation.