ABSTRACT
The Steinwasser water intake is a 20 m high dam which was endangered by an instable rock cliff located above its left bank. In 2021 the tachymetric monitoring assessed an acceleration of the deformations. The safety of the Steinwasser dam was assessed using an acting force derived from the crash model provided by geologists. The results showed that the structural safety of the dam in case of an uncontrolled rockslide is not fulfilled, thus immediate measures were planned to excavate the material in stages with controlled blasting. The dam was protected by a 1 m thick Rockfall-X mattress and part of the reservoir near the left dam abutment was filled with gravel material to dampen the impact of blasted rocks. The blastings were implemented in such a way that the detached elements (individual boulders) were no bigger than 1 m3 in volume. Vibrations were measured during the construction works in order to ensure the safety of the dam. Regular measurements and the early implementation of appropriate measures are the key components to ensuring a high level of safety while guaranteeing the operation of the Steinwasser water intake.
