Flood protection in Røyslimoen

Lillehammer Municipality wanted to reroute the Åretta River due to flood problems. Such a rerouting entails rerouting existing water supply and electrical cables, new bridge constructions, adjusting road routes, landscape adaptation, and flood calculations. Multiconsult has assisted with this work.

Lillehammer Municipality has in recent years been exposed to major flood damage after intense rainfall events. Multiconsult has followed the assignment Flood protection measures in Røyslimoen from design to construction site follow-up.

In 2013 and 2014, major damage occurred to infrastructure, commercial and residential buildings near the Åretta River in Røyslimoen. Some of this is due to a lack of capacity in important culverts that carry the river past the commercial buildings and under Røyslivegen. In order to flood-proof the area, the municipality wanted to reroute and open up the Åretta River in a new floodway over a distance of around 350m. In connection with the new floodway, the road route, which was previously destroyed by floods, was also improved with increased traffic safety.

Complex interdisciplinary assignment
It has been a very complex interdisciplinary assignment with a lot of logistics and restructuring. Multiconsult has provided all the disciplines in the project design, and the zoning plan work went in parallel with input from Multiconsult. Major improvement work has been done in the ground with restructuring of the water supply and electricity, and RIB has constructed two new bridges, a road bridge and a pedestrian/cycle bridge. Vei has designed road surfaces, bus bays and complicated intersection solutions, and RIB water resources and hydrology have calculated and designed the floodway in collaboration with LARK. LARK has also designed an amphitheater integrated into the plastic ring along the riverside and a living area by the river, centrally located in the area.

When Multiconsult was engaged to flood-proof the area, two preliminary projects had already been completed. The site is a hub just outside Lillehammer, so it had the potential to become something more and the side terrain has been converted into a park area, including an amphitheater that also provides access to the floodway and facilitates a recreation area with benches and vegetation.

For both Multiconsult and the executing contractor, it has been a complex VA assignment. It has been necessary to reposition large water and sewage installations in the ground, and there have been strict sequence requirements in order to maintain the water supply to the entire district during the project. Multiconsult is proud to have developed the project together with the client, and to have come up with a sustainable solution that adds value to the area.

The feedback from the client was: "This is more than a flood protection facility, it has become an incredibly nice district center."