Large leakage incident in a Norwegian concrete faced rockfill dam due to ice build up

Abstract

Aursjø dam is a concrete faced rockfill dam (CFRD) in central Norway built between 1950 and 1958 and owned by Statkraft. The dam was originally constructed with an upstream face consisting of wooden planks, which acted as the impermeable element of the dam. The dam underwent a large rehabilitation between 2005 and 2006, when the wooden planks were replaced with a reinforced-concrete slab. In 2017 a large leakage event occurred at the dam and at its peak was estimated to be up to 600 l/s. This paper covers the incident itself including the emergency response, the investigation into the cause of the high leakage, the potential effect on dam safety, and finally the recommended measures implemented at the dam. During the detailed investigation the cause of the leakage was identified as the release of water after an ice dam within the dam body burst. Ice build-up and subsequent rapid release of water is not an unusual occurrence at rockfill dams in Norway and there are examples where the same phenomena has occurred at other dams.