Uniper : Resealing the Roßhaupten Dam successfully achieved!

Eighteen months of work has paid off: In mid-September, we celebrated the successful completion of the project 'Resealing the Roßhaupten dam.' After more than 60 years in operation, in April 2018 Uniper began to invest around 30 million euro in resealing and reconditioning the dam, as well as in installing a state-of-the-art fiber-optic monitoring system. As asserted by Eckhardt Rümmler, Uniper's COO, at the closing ceremony of the project in September, hydropower is 'a key technology when it comes to generating power. We are proud that we have these power plants so we can contribute to the success of the energy transition.'

The dam and Lake Forggensee, which was formed when the dam was erected, are responsible for absorbing large influxes of water from snowmelt or heavy rainfall and regulating the amount that flows into the River Lech. For decades, these measures have been preventing flooding on the River Lech and improving the flow of water during the winter. Lake Forggensee is drained every fall to ensure there is sufficient capacity to allow for snowmelt. After 64 years of filling and draining, the dam started to show signs of wear and tear in winter 2017/2018, indicating it was time for a restoration. This prompted Uniper to work with internal and external experts and the relevant authorities to develop a multi-stage renovation concept. The first phase of the project involved exploring below ground and using targeted injections of concrete to stabilize the structure, as well as installing additional measuring devices for monitoring the dam. The second phase consisted of building a soil/cement slurry wall along the entire length of the dam and installing a state-of-the-art fiber-optic monitoring system. The final phase was to complete the resealing project. This took a remarkably short time despite the technical, geological and climactic conditions at the construction site, which was situated at the foot of the Allgäu Alps almost 800 meters above sea level. Heat, cold, storms, rain and snow - the weather threw everything it had at the project. And that wasn't the only problem: the soil/cement slurry wall had to be dug up to 30 meters into incredibly hard rock beneath the dam.