Beneath Stockholm’s beautiful Kungsträdgården park, located downtown with a view of the Royal Palace, lies a pumping station that is key to the city’s wastewater management. Xylem was recently responsible for installing more powerful pumps in the station in order to handle increased capacity.
The pumping station under Kungsträdgården handles all of the wastewater and storm water in Stockholm’s inner city, pumping it to the nearby Henriksdal wastewater treatment plant.
“The need for more pumping capacity arose when a new bus terminal was planned in connection with nearby renovations,” says Stefan Tenglund, a manager for Stockholm Water. “The new terminal would be in the same place as our wastewater tunnel, so we needed to extend the sewer lines by 250 meters. This additional length meant that more powerful pumps were required.”
The upgrade involved replacing four large Flygt 150 kW pumps with four Flygt 170 kW pumps. The power supply into the station and frequency control was also replaced at the same time. The Flygt pumps were originally installed between 1994 and 1996, in order to increase the reliability of Stockholm’s wastewater and storm water flows.
“It was time to replace the control system, but the pumps have certainly been sufficient for the last 20 years, and we would not have needed to upgrade them had it not been for the nearby renovation project,” says Tenglund. “This large installation project has demanded a lot from everyone involved. Although the pumping station is about 400 square meters, it is a crowded space so a lot of calculations were involved to get the equipment in place.”
Low operating costs essential
“This was a really interesting project to be involved in,” says Tomas Ström, the salesperson at Xylem responsible for the project. “It was a challenging job as it is a cramped space that is difficult to access. In addition, the pumps are located far below ground and can only be accessed by a special elevator.”
In order to transport the original pumps underground, a custom elevator was built that could carry three metric tons. This special elevator, located behind the Royal Opera, is hidden to the many people who visit the park every day. The elevator only pops up from the ground when it is needed.
“Our department at Stockholm Water includes 26 people who operate and maintain approximately 500 sites in the Stockholm area,” says Tenglund. “In order for this to work, everything must function as it should. Therefore, we always look at operating costs when we invest. So it is no coincidence that we chose the Flygt pumps for the Kungsträdgården pumping station.”