Saint Jean section

This is the first of the Ollomont mines to be discovered and exploited, starting from the early 1700s. There are several access tunnels, upstream of the village of Les Rey. In the early 1900s, the lower Sant’Anna tunnel is opened, making it easier to transport the material extracted to Les Rey’s factories.
The section rises vertically over dozens of excavation levels from an altitude of 1040 meters to 1525 meters, for about 150 meters horizontally.
In 1808 a system with a hydraulic wheel is created for the disposal of leaking water, which has always been a serious problem in the reservoir.
In the second half of the nineteenth century, under the management of the Belgian count Victor Seyssel d’Aix, the Aosta Valley scientist Innocenzo Manzetti was commissioned to create a new system for draining the infiltration water from the well.
To facilitate transport operations, in 1906 the excavation of a lower tunnel began in the hamlet of Frissonière, thus allowing direct connection to the Santa Barbara level.