Copenhagen Metro Sydhavn Extension Dewatering Design 

The Copenhagen Sydhavn Metro Extension—designated as Line M4—is a €500 million infrastructure initiative aimed at enhancing metro connectivity to the city’s southern districts. The construction contract, awarded to a joint venture between Hochtief and Vinci, included five underground stations and two crossover structures. A practical and cost-efficient dewatering strategy was essential to support a competitive tender process, initially estimated at up to €15 million.

While dewatering for the station boxes was relatively straightforward due to the limestone geology with minor fissures and low groundwater flow, the discharge of abstracted water into Copenhagen’s iconic harbour required compliance with drinking water standards.

Leveraging its global expertise in metro dewatering systems, WJ was uniquely positioned to deliver the design contract.

The design phase incorporated 3D modelling to support environmental permitting, along with detailed cross-sections, well construction specifications, and layouts for both dewatering and treatment infrastructure. These elements were crucial for planning within the constraints of a dense urban setting.

Ultimately, the dewatering contract was awarded for €10 million, achieving a €5 million saving compared to initial estimates. The works were completed successfully, enabling the metro extension to open as scheduled in 2024.