Käppalaverket, Sweden

Doing the dirty work: a wastewater plant upgrade

About

Challenge

The Käppalaverket Treatment Plant needs to expand its wastewater treatment capacity from 700,000 to 900,000 people and upgrade its water treatment methods. All this must be done while the facility continues to operate.

Solution

Upgrading the facility includes rebuilding large water tanks and replanning parts of the water treatment methods. This requires advanced construction solutions underground and in hard-to-reach locations.

Value

By expanding its treatment capacity and modernising its processes, the facility is prepared to meet the demands of a growing population while supporting a healthier Baltic Sea.

Specifications

Upgrade

The facility wants to scale up its capacity and upgrade its cleaning methods.

Facility

Cleans wastewater from eleven municipalities – 50 million m³ of water per year.

Location

Lidingö outside Stockholm

Period

2020–

Country

Sweden

Services

Construction; geotechnics; groundwork; water and sewage; and traffic planning.

Cleaner water for a growing region

Built in 1969, Käppalaverket treats wastewater from more than half a million people in eleven municipalities.

The project referred to as Käppala 3.0 will increase the capacity of the facility to accommodate the growing population as well as upgrade the water treatment methods. This will also help improve the environment in the Baltic Sea, as nitrogen emissions will be reduced by 40%, phosphorus by 33% and organic matter by 25%, compared to today.

“There are many reasons why this is a great project. Not least because it supports sustainability by helping to improve the environment in the Baltic Sea. We have been involved across key areas of the project, helping to coordinate the complex upgrades required to increase capacity and improve treatment performance.”

Håkan Skoglund, Vice President, Industry and Buildings, COWI

Time to open the creative toolbox

Because the new water treatment process has not previously been tested on such a large scale, innovation and creative problem-solving have been critical throughout the project.

Working underground in confined spaces has been a constant challenge, making buildability a key consideration throughout the planning process.

You might also come across a closed door. Because the facility remains operational during the upgrade, not all areas are accessible, so sometimes you must wait for a pool to be emptied. We also had to design sluice gates and other devices to control water flow.