Marécottes: refurbishment of the reservoir gates

We obtained contracts for several lots, including structural repairs (reinforced concrete and sealing work), as well as work on the headrace. The tasks assigned to HYDRO Exploitation involved the inspection and renovation of the reservoir gates. .

With close collaboration between the mechanical engineering unit, the assembly team and Hydreo, the subcontractor which made the gates, the following work was completed within very tight deadlines, even though time was lost due to the Covid-19 pandemic:

• Removal and replacement of two gate valves, 2300mm in height and 2000mm in width located at the reservoir’s inlet, including their drive units.
• Removal and replacement of two gate purge valves, 700mm in height and 750mm in width made entirely from stainless steel.
• Removal and partial refurbishment of two outlet gates, 3500mm in height and 2660mm wide and weighing over 18t each.
• Re-installation of the inspected and refurbished gates.

The Marécottes balancing reservoir (in the commune of Salvan) forms part of the Vernayaz hydroelectric facility. The reservoir enables water to be put under pressure before it travels to the Vernayaz hydroelectric plant. It was constructed between 1924 and 1926 and was designed by the engineer Alexandre Sarasin. The north wall is constructed from reinforced concrete and rests on the ground. The south wall was a daring construction for the period, comprising 42 slender inclined arches resting on buttresses.