NIRAS Keeps an Eye on Kriegers Flak Seals and Birds

Birds and seals have got GPS transmitters on them, and the birds are monitored with radar in preparation for the establishment of Kriegers Flak offshore wind farm.

It is a requirement for large construction projects such as ports, bridges and wind farms, that they must not affect the nature significantly. This requirement is particularly important when it comes to specially protected species. It has been NIRAS’ task to ensure that this requirement is met when building Denmark’s largest offshore wind farm in the Danish part of the shallow area Kriegers Flak in the middle of the sea between Denmark and Germany.

Therefore, NIRAS together with its sub-consultants developed new innovative methods to investigate occurrence of different species and predict the environmental impact of the 600 MW offshore wind farm, which will be one of the world’s largest when completed in 2020. The result can be seen at Energinet.dk, that has just released a significant part of the EIA of Krieger Flak, which NIRAS is close to complete on behalf of Energinet.dk. An EIA (Environmental Impact Assessment) procedure will examine the environmental impact of a construction project and establish specific environmental requirements that developers must comply in the assessed project.

“For every EIA we do, there are new challenges, and that encourages us to constantly innovate and adopt new methods,” said Mette Jeppesen from NIRAS, project manager of the EIA of Kriegers Flak offshore wind farm. “Kriegers Flak is on the migration route of cranes, that passes from Sweden to central Europe on their way from north to south and back again,” he explained.

The crane is a protected species, and its journey is as a new method among others things monitored by attaching GPS transmitters to the birds while also monitoring them by radars placed on a platform on the German part of Kriegers Flak. “It has given us a much more detailed picture of the activities of the animals than we would otherwise have been able to achieve,” said Jeppesen.

The investigations of the cranes have been conducted by DHI which Niras has hired as sub-consultant. The conclusion of the detailed studies using new methods such as monitoring with GPS and radar is that an offshore wind farm at Kriegers Flak will not have any significant effect on the population of cranes.

But when all the known planned offshore wind farms in Northern and Central Europe are realised, it will probably affect the population of cranes significantly. NIRAS together with its UK office has developed a special stepwise approach to assess whether or not the project may affect different Natura 2000 sites which the cranes are attached to cross borders. A Natura 2000 site is a natural resort that is selected to conserve species and habitat types subject to EU regulation.

There are 252 Natura 2000 sites in Denmark. Together the sites cover 8.3 percent of the Danish land area and 17.7 percent of the Danish sea. Sites in other countries come in addition to this. It is this method from NIRAS’ UK office and putting GPS on cranes that are new. A part of the EIA study has been to demonstrate that the project cannot harm cranes with their protection through Natura 2000 as the underlying basis.

At the same time, the construction of a large project with the right countermeasures will not threaten the seals and porpoises in the area. NIRAS together with Energinet.dk helped to develop a method to assess and manage underwater noise in relation to marine mammals. The seals in the area have also been monitored with GPS transmitters.

Mitigation measures are construction measures designed to neutralize undesirable environmental effects of a construction project – in this case the wind farm, where mitigation measures will ensure that the wind farm does not create underwater noise that disturbs communication of the marine mammals.

The preparation of the EIA report Kriegers Flak offshore wind farm has so far taken three years, which is a long time because it is a very large project with many field studies. Many EIAs can be completed in a year’s time. The report will now be submitted to a public hearing after the autumn break. 

Image: Energinet.dk