Rehabilitation of a sea wall in Mandal, Norway

Gismerøy is a small island close to the city of Mandal on the south coast of Norway. The site has been selected for industrial development. An industrial estate was developed close to the sea with no particular attention to protection. The landfill and a factory building were nearly completely destroyed by two consecutive storms in May and October 2000. After the second storm, detailed studies and model tests were carried out to specify a reliable and safe design. The new design was based on a berm breakwater principle, but with some important local adaptations. It was also discovered that the wave runup due to a rock formation was so great that the rock would have to be removed. This work was especially challenging because there was a strong wish to preserve the infrastructure and investments that had already been laid down, and because the areas adjacent to the site are designated as natural recreational areas.