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June 2, 2011
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Four parallel technical visits are proposed to the delegates and the accompanying persons:
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T1 Pumped storage project Nant de Drance
The pumped storage scheme is actually under construction and will connect the reservoir of the 180m high Emosson Arch Dam to the Vieux-Emosson reservoir located 250m higher. The powerhouse capacity will be 600 MW. The project is located near the French border with great views on the Mont Blanc Massif and the Valley of Chamonix. Due to environmental constraints, the entire project is underground, including a cavern system for the powerhouse and two water intakes in existing reservoirs which will remain in operation during construction.
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T2 Heightening project of Grimsel reservoir and Gotthard base tunnel
The Gotthard base tunnel presently under construction consists of two tubes, each one being 57km long. When put into operation in 2017 it will be the longest railway tunnel in the world. Opportunity will be given to visit the information center at the Northern portal (Erstfeld) that gives a realistic picture of the technical challenges encountered during the construction and how they were mastered.
The tour will bring the visitors to the area of the Grimsel Pass where the heightening of the two dams forming the reservoir of the same name is under study: the Spitallamm Dam is a 114m high arch gravity dam that shall be transformed in a 137m high double curvature arch dam, whereas the Seeuferegg Dam, a 45m high gravity dam, will be raised to a height of 68m by adjunction of a hollow concrete structure at the upstream side.
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T3 Göscheneralp Rockfill Dam and Lucendro Buttress Dam
The 155 m high Göscheneralp Dam has been built from 1955 until 1962. It consists of a central impervious core with rockfill shoulders. To increase the reservoir volume by 15% it is foreseen to heighten the dam by 8m while raising the crest and adapting the appurtenant structures. Construction works are scheduled to start in Spring 2011 and to last until 2013
The excursion will continue in the Reuss Valley up to the Gotthard Pass with a visit of the 69m high Lucendro Buttress Dam, the only dam of this type in Switzerland, completed just after WW II. The buttresses have been laterally reinforced by massive struts to increase the stability of the structure.
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T4 Sediment Bypass Tunnel at Solis Dam and Marmorera Dam
The reservoir of the 61m high Solis Arch Dam completed in 1986 on the Albula River is subject to an important accumulation of coarse sediments especially during floods. In order to keep a sufficient storage capacity for energy production the design of a 850m long by-pass tunnel has been envisaged. The tunnel will still be under construction at the time of the visit.
The second part of the excursion will enable to see the 91m high Marmorera Rockfill Dam, that was the highest in Europe at the time of its construction (1951-1954). The dam is perfectly integrated in its surroundings and beside some remedial treatment of its foundation it has performed very well over more than half a century.
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Technical visits 
