Sankt Annæ Plads
The area around Sankt Annæ Square, Kvæsthusgade and Nyhavn East in Central Copenhagen has been renewed to improve city life, architecture, traffic and parking. Together with the renewal, Sankt Annæ Plads was climate adapted to reduce cloudburst problems. The site has been converted into a so-called cloudburst street, where the water from extremely heavy rain is led away from the old houses and into the harbour. The whole square has been shaped like a bowl, its lowest point in the middle of a green park. In addition, rain water pipes have been laid underground to achieve the necessary water flow. Now the rain water is quickly led away from the facades, down towards Kvæsthus Square and into the harbour.
The solution has three advantages. It creates more space in the sewer so that wastewater is not easily pushed up on the street to the citizens, removing large amounts of rain water in a short period of time, so the risk of floods becomes smaller and saves energy because rain water will no longer be pumped through the sewers and beyond treatment plants.
The climate adaptation part of the Sankt Annæ Project was completed by the end of May 2016. The project is dimensioned in accordance with the Copenhagen City Climate Plan. It is the goal that at a 100 year rain event there will be no more than 10 centimetres of rain water at the facades of Sankt Annæ Plads.
The desire for a renewal of Sankt Annæ Plads and the surrounding streets arose in connection with the Kvæsthus project, where an underground parking facility was built.
Rain water is now led away from the facades and gathered into four green, recessed gardens. They act like rain water basins in case of heavy rain and cloudburst. They create room for about 500,000 extra litres of rain water in the middle of the square.
In the event of heavy rains and cloudbursts, rain water and sewage will flow separately in each system. Four new rain water pipelines - two big cloudburst pipes and two smaller roof water pipes - will lead rain water into the harbour. It will reduce the pressure on the sewers and minimize the risk of flooded roads, squares, courtyards and basements.
Along the square runs a green area with flowering beds and space to stay on the benches and in the grass. In the middle there is a recessed area between rows of granite stone. Here the water is collected at extremely heavy rain.
The water is directed down to the harbour - the last distance in a pipeline.
At each side of the square there are wide sidewalks and a one-way, narrow street for cars and cyclists. The road is designed with bumps and it is so narrow that cars can not overtake cyclists. This means that the speed is kept down to max. 30 kilometres per hour. Throughout the project, work has been done systematically to combine a technical management of the rain water to create better conditions for the citizens.
The total budget for the Sankt Annæ project was well over DKK 100 million - or DKK 25 million less than originally budgeted. Of these, the cloudburst protection costs about DKK 40 million. The conversion of Sankt Annæ Plads costs more money than the municipality of Copenhagen had available. Several private partners entered the project. Initially, Realdania and Jeudan, who had their headquarters at Sankt Annæ Plads. In total, the four funds and Realdania delivered DKK 26 million. The municipality of Copenhagen contributed DKK 36 million and HOFOR by DKK 40 million.
Schønherr was responsible for the design and was a total consultant at the Sankt Annæ Project. The construction work has been coordinated and implemented by the Sankt Annæ Company.
The area is owned by the City of Copenhagen, which is responsible for operation and maintenance.
Both water engineers, landscape architects, urban life and traffic experts have contributed each their solutions to the project. The difficulty and challenge of the project has been to get the various disciplines to work together from the beginning, and to develop the project with mutual respect for each other’s disciplines.
Extra material: Presentation from HOFOR, Youtube skybrud HOFOR