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New stormwater tunnel to prevent floodings in Copenhagen

Photo: Jeanne Kornum

​The construction of a 580 meter-long tunnel to manage cloudbursts in the Danish capital of Copenhagen has commenced. The tunnel is an important step along with a range of other projects to prevent new floodings. COWI is involved both underground and above.

When a severe cloudburst hit Denmark in August 2011 many homes, offices and businesses were flooded and the cost of the damage was unprecedented.

Now, a 74 tons Tunnel Boring Machine has been launched to construct the Østerbro Stormwater Tunnel in the eastern part of Copenhagen as a means to reduce future risk.

The 580 meter-long tunnel is part of a governmental strategy to reduce the burden on Copenhagen’s exhausted stormwater and sewer system, which cannot absorb the excessive amount of stormwater created by global climate change.

Additional tunnels and other climate change adaptions are underway, and COWI is consulting the municipality and Greater Copenhagen Utility (HOFOR) in planning and implementation on various projects touching upon many different aspects from landscape architecture to water flows and tunnel construction.

“It is a very complex challenge to manage cloudbursts and prevent floodings, but it helps that we work so closely together across the different disciplines. It enables us to provide coherent solutions,” says Louise Risør, Head of Section and part of the 'Cloudburst'-group at COWI.

Extra lungs for the city

In Copenhagen’s action plan for a climate proof city there is a strong emphasis on establishing retention basins and canals with a recreational, nature and environmental value.

Among other projects is the public park Enghave Parken, where a makeover is underway to create room for 24.000 m3 of stormwater as well as green and lush areas for the citizens. 

“The solutions should obviously create as much value as possible. But the recreational areas and basins on the surface cannot accommodate all the extra stormwater. When severe cloudbursts hit densely built cities some of the water has to go underground and be led to the sea. As a consequence, we will see many more stormwater tunnel constructions in the future,” says Leo Lund Mathiasen, COWIs project manager on the Østerbro Stormwater Tunnel.

COWI is a market leader within tunnel design and has designed kilometres of complex sewer systems and stormwater tunnels around the world.

The construction of the Østerbro Stormwater Tunnel is expected to be finalized in early 2017. 

The Østerbro Stormwater Tunnel

​The Østerbro Stormwater Tunnel will receive water from both moderate, daily rainfall as well as more uncommon cloudbursts. During severe cloudbursts around 12 m³/s water will be discharged to the harbour basin. The tunnel is 2,5 meters in diameter and runs 8-13 meters under the surface.

COWI is providing project management and detailed design on the tunnel for Greater Copenhagen Utility (HOFOR), one of the major players in the implementation and operation of cloudburst protection and other climate adoption projects in the Copenhagen area.

LAST UPDATED: 19.01.2017