Swiss engineers complete new dam to repair Spitallamm structure
- Swiss engineers have completed a 113-meter-high dam constructed directly in front of a nearly century-old structure to resolve a massive vertical crack in the original wall.
- The new dam features a 212-meter crest and is designed for a minimum operational lifespan of 100 years.
- Construction of the original Spitallamm dam on Lake Grimsel began in 1925 and concluded in 1932.
Swiss engineers have completed a 113-meter-high dam constructed directly in front of a nearly century-old structure to resolve a massive vertical crack in the original wall. The project, finished in 2025, allowed the associated hydroelectric plant to remain operational throughout construction, avoiding the energy production losses that would have resulted from draining the reservoir and demolishing the old dam, according to PiataAuto.md.
The new dam features a 212-meter crest and is designed for a minimum operational lifespan of 100 years. According to PiataAuto.md, the new structure possesses a calculated resistance twice that of the original construction.
Spitallamm Dam structural failure and engineering solution
Construction of the original Spitallamm dam on Lake Grimsel began in 1925 and concluded in 1932. The 114-meter-high structure held up to 90 million cubic meters of water. In the early 2010s, engineers discovered a large vertical fissure where a portion of the construction was separating from the resistance structure, allowing water to penetrate the dam.
Standard repair protocols would have required draining the lake, halting the hydroelectric plant, and demolishing the old dam to build a new one. PiataAuto.md reports that this process would have taken years and blocked energy production. To avoid this, the project team began constructing the new dam immediately downstream of the old one in 2019.
Logistical constraints and construction timeline
The project site is located in a mountainous region where weather conditions restrict construction to approximately four to five months per year, typically between May and September or October. To compensate for this window, crews worked 24 hours a day, seven days a week during active periods.
Engineers operated in an extremely narrow workspace between mountain slopes and utilized digitally coordinated cranes to manage the build, according to PiataAuto.md.
Integration of the old and new structures
Once the new dam was completed, operators performed a controlled reduction of the lake level to clear sediment from the bottom. Engineers then created several openings, described as windows, in the old dam.
When the lake was refilled, water entered the space between the two dams. This configuration ensures the old structure no longer bears the primary pressure of the lake, leaving it as a largely submerged structure with a significantly reduced role while the new dam absorbs the force of the water, PiataAuto.md reports.
Grimsel energy storage capacity and future expansion
Lake Grimsel functions as part of a pumped-storage energy system. The Grimsel 2 plant consumes 392 MW when pumping water and delivers 388 MW to the grid when water is released through turbines. Additional capacity is being prepared in the area to deliver another 168 MW.
The current construction was engineered to allow for a future height increase of 23 meters. This expansion would increase water storage and energy capacity. While the structure is already prepared for this modification, the project is currently undergoing approval procedures, according to PiataAuto.md.