Climate protection of Kolding Å

The technical solution
The pump and lock system has an important double function and protects the city against both rising sea levels and heavy precipitation. The system blocks the seawater and uses Kolding Å as a retention basin. When the lock closes, the pumping station transports water out into Kolding Fjord lowering the water
level. Thus, Kolding Å maintains the necessary capacity to accept water from elsewhere without overflowing its banks. The system protects Kolding in the event of flooding or torrential rain. Vibeke Gregersen, expert within climate adaption initiatives, explains:

In the event of raised sea levels, the 2.8 meter lock-gates, above sea level, will block the seawater from entering Kolding Å. Additional dikes and floodwalls will serve the same purpose.

Hotline to the hydraulic laboratory
Large amounts of water will be transported over the lock, and the speed of  ransportation must therefore be carefully modulated as to avoid bank erosion and the resultant consequences for the river’s ecological balance. To identify the best solutions, Vibeke had assistance from our colleagues in Næstved, who
have experience designing pumping stations. They were able to define the design requirements for the pumps and determine the costs. Brian Bryder Rasmussen, who also took part in the project, explains how it was important to validate the concept internationally because there was no basis for comparison in Denmark.

Challenges at the bottom of Kolding Å
Our office in Næstved also prepared the geotechnical report concerning soil conditions. They discovered that the soil was extremely soft and that a sufficient load-bearing capacity would not be reached before reaching a drilling depth of 14-15 meters. The report concludes that the pump and lock system must be based on a reinforced pile foundation which causes additional design requirements as the piles must be driven down 19 meters or deeper. The necessary drilling also allowed for environmental examinations revealing contaminated soil. Our environmental specialist from Southern Denmark, Jørgen Raaen Lund, was in charge of the strategy for soil, sludge and water management.

A junction for people and animals
The environment is central to the project and, to complete our cross-regional collaboration, our department for Nature and Water Management in Copenhagen helped prepare the environmental impact report. The pump and lock system is built in a protected area, and the construction process must therefore respect the area’s flora and fauna. This influences not only where and how the project can be built but also when. The construction needs to happen at a time when it does not disturb the fish’ spawning season or the porpoises’  breeding season. If you are lucky, you might run into an otter or a dolphin in the area and these are also considered in the report that describes a lot of additional
project aspects including noise, vibration, dust and archaeology. Several other design requirements are introduced to protect fish and other users of the
river including kayakers, jolly boats and other sailing activities. The gate-locks must be more than 20 meters wide to allow fish and boats to pass without difficulty and the technical solutions cannot harm the area’s fauna. Because of the project’s placement, our client consultants have been in contact with
pretty much all the departments of Kolding Municipality and Kolding harbour. Vibeke Gregersen notes how the project required extensive coordination: