Carlsberg City: Cloudburst management in historic district of Copenhagen

Carlsberg Byen (Carlsberg City) is an old brewery site, located in the central part of Copenhagen. During the last decade, a lot of work has been completed in order to turn the area into a new neighbourhood complete with a mixture of residential areas, schools, businesses and commercial areas.

Due to more frequent cloudburst events during the last decade in Copenhagen, the city has established cloudburst management plans, and the private Carlsberg City development needed to be part of this city-wide strategy in order to ensure proper stormwater management and sufficient detention in the area.

One of the big challenges for Carlsberg City is its location. Carlsberg City is located on a small hill, with a significant slope. The area drops approximately 18 meters, with the highest point to the West and the lowest point to the East, resulting in a large amount of run-off and a high risk of flooding in the lower, adjacent areas.

In collaboration with landscape architects from Schønherr, Ramboll designed new green urban spaces capable of detaining rainwater to decrease the risk of flooding and simultaneously be used for recreational activities.

The task included screening the area for possible locations and size of detention basins, helping to negotiate the required detention volumes with the authorities, setting up a hydraulic model for the area and designing the pipe system and the retention basins.

The basins can store a total volume of 3,000 m3 rainwater and thereby handle a cloudburst event with a statistical return period of 10 years. The basins are filled up consecutively by using local flow regulators to retain the water.

The largest basin located downstream, is a combination of underground storage with an overflow possibility to an adjacent football field.

All basins are designed to include recreational elements like playgrounds and insect-friendly urban nature zones, blending flood resilience with community enjoyment.