Cloudburst protection at Østerbro
Construction of complex cloudburst pipeline
We are building a cloudburst tunnel under Strandboulevarden in Østerbro, Copenhagen, which will form the backbone of a new rainwater management system, transporting every day rainwater and storm water to the harbour.
Sweco has assisted HOFOR as the turnkey consultant for the project, which is being done in parallel with the establishment of a new urban park. Strandboulevarden must therefore also be changed, so that traffic is routed on one side of the road, while the new recreational cloudburst park is placed on the other side.
- Realised, 2021
- Advisory role
- Lead consultant
A challenging task that evolves day by day
The project is very complex because of the many stakeholders, the different competencies and professional groups that have to work together, and the fact that many aspects of the project are evolving along the way. The project is being carried out in line with HOFOR’s newly developed requirements specifications for tunnelling, feasibility studies and the like.
Extensive feasibility studies have been carried out, including geotechnical studies, measurements have been made, foundation conditions of nearby properties have been investigated, and risk analyses and risk management have been performed. The project has also been coordinated with the cloudburst park and the consultant on this project.
The cloudburst tunnel has been designed as a pipeline under Strandboulevarden, about 920 meters (Ø 2000 mm) in length, and about 180 metres along Gl. Kalkbrænderivej (Ø 2500 mm). Four shafts and structures housing flushing plants will be established – three using secant piles and one through excavation of existing pile sheet wall. The pipelines will be established by pipe jacking with a closed front from a central pit, using a slurry tunnelling machine.
Digital management of the water volumes
Electricity and an ICS (industrial control system) have been essential to the project, as the critical stowage levels determine how the control system should handle the water volumes.
Water table measurements upstream and local measurements determine when the cloudburst flaps are opened, while local water table measurements and the general water table level at the emptying pumping station determine when the damper opens. The way the respective levels are handled is optimised based on level and activation elevations and measurements in the system.
An outlet pumping station will also be established to empty the cloudburst tunnel under Strandboulevarden and Gl. Kalkbrænderivej after an overflow event. For this purpose, a cabinet containing a control board will be erected on the street. Level measurement signals will be transmitted from the control board to the flushing flaps via GPRS (General Packet Radio Service).