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Aarhus mature site (Denmark)

Aarhus River before restoration

Aarhus is the second-largest city in Denmark. Traditionally a center for shipping and agricultural processing industries, the city is transitioning to become a center for research and development, as well as a manufacturing center for clean energy technologies. As part of this, Aarhus has made considerable investments in environmental planning in order to attract a dynamic and well-educated population.

Aarhus is developing water-related recreational elements to enhance the quality of life in the city center and old harbour area. These include two different but related objectives: to restore a segment of the Aarhus River flowing through the city center that had been diverted underground; and to improve the hygienic quality of water in the harbour so that the harbour is suitable for bathing.

Aarhus River after restoration

Aarhus River after restoration

An innovative, integrated solution was developed to manage water quality in the river and harbour and support the restoration of the river in the old city center. The solution includes a real-time monitoring and control system for combined sewer overflows, as well as a warning system for bathing water quality. The real-time control system coordinates storage of sewer overflows in storage tanks to optimize system-wide capacity and minimize spills. The warning system for bathing water quality was established because the EU Bathing Water Directive permits one non-compliant event per year if a warning system is in place; otherwise, a non-compliant event is permitted only once every four years. The installation of the warning system was estimated to save 25 million Euros that would have been required for additional infrastructure to reduce the frequency of non-compliant events.

Contact for the mature site: Niels Riegels, DHI (