A Race to fix a Cracked Dam (Grimsel)

Arrival & Construction Site

An excellent way to reach the venue was with the PostAuto from Meiringen (BE). Fearlessly climbing along hairpin curves, the bus driver provided memorable and insightful commentary along the way up to the Grimsel Hospitz (2,165 meters above sea level).

The thirty participants were equally split into English and German speaking groups. The morning was spent learning about the actual crack in the Spitallamm dam, and the efforts that were being made to build a replacement dam, almost a century later, right in front of the original wall. This time, with one tenth the number of personnel.

Approximately one hundred persons, including machine operators, miners, carpenters, masons, explosive experts, joiners, construction workers, road builders, mechanics, electricians, foremen, supervisors and of course some engineers, have been working since 2021 to turn 220,000 cubic meters of concrete into a new dam approximately 113 meters tall with a crest length of 212 meters.

With the help of two massive cranes, 92m and 87m tall respectively, the completion of the new dam wall is scheduled for September this year. Subsequently, the Lake Grimsel will be drained for final constructions, before re-flooding of the lake will commence on April 15^th, 2025. The process of re-filling is expected to take six months, after which final tasks will be completed to ensure that by 2026 the powerplant is back in full operation with the new Spitallamm dam. The original dam – technically under historic monument protection (Denkmalschutz) will remain standing, but fully immersed under water by both sides.

Picnic Lunch & Networking

A designated area in front of the iconic Grimsel Hospitz was organised with picnic tables and lunch bags. The extended lunch break gave participants plenty of time seep in the breathtaking views of the landscape and construction site, while connecting with fellow ETH Alumni.

Visiting the Underground Power Plant

Through a series of tunnels 150 meters deep under the Lake Grimsel, the tour continued with a visit to the massive turbines, pipes and pumps. This infrastructure permits the 13 power plants, operated by KWO, to generate 1,317 megawatts of power with the help of of 28 turbines.

An "icing on the cake" was visiting the Crystal Caves (Grotto), which were accidentally discovered in 1974 by construction miners, and were a true feast for the eyes. Travel underground was both by foot and minivan through portions of the almost 160km of tunnels interconnecting various elements of the power plants.