Allgrunn AS is a collaboration between ACO Anlegg, Opshaug and Busengdal, and specializes in partial and main contracts within groundwork and infrastructure. The company has been involved in several significant projects, including as the largest subcontractor for Skanska Norge in the construction of Nordøyvegen, which includes 13 km of undersea tunnels and three bridges.
In addition, Allgrunn has participated in mass replacement and foundation work for Subsea 7's factory, as well as work on projects for the Norwegian Road Administration, including Ørskogfjellet. The company was named Construction of the Year in 2022, which highlights their contribution to the construction industry.