NIRAS is responsible for the environmental impact assessments (EIA) for two proposed offshore wind farms in the strait of Øresund on behalf of Greater Copenhagen Utility, HOFOR.
- SDG: #7, #14
- SECTORS: Energy, Offshore Wind, Environment and Ecology
- COUNTRIES: Denmark
- CLIENT: HOFOR (Greater Copenhagen Utility)
- DURATION: March 2019 - ongoing
NIRAS’ environmental impact assessments (EIA) for the two offshore wind farms Aflandshage and Nordre Flint includes the wind farm areas, marine cable corridors, landfall, substations and cable corridors onshore for grid connection.
NIRAS carries out the EIA in cooperation with eight subcontractors: DCE - Danish Centre for Environment and Energy, GEUS, DNV, BioApp, Profus Naturrådning, Krog Consult, SEMCO Maritime, and DHI.
NIRAS has assisted HOFOR in preparation of scoping reports and preparation of the overall technical project description for both offshore and onshore installations.
NIRAS assistance also involved environmental assessment reports, background reports on a number of topics, documentation and material for public consultations, including ESPOO, and commenting on incoming public consultation responses.
The reporting has been carried out in close dialogue with HOFOR, and NIRAS has also assisted and participated in the dialogue with the authorities, which are the Danish Energy Agency, the Danish Environmental Protection Agency and the affected municipalities, about the EIA and the process.
As a basis for the working process NIRAS has prepared a webGIS solution, which has been used as a dialogue-tool throughout the process and as a basis for the preparation of the numerous maps for the reporting.
Two phases of assessments
The assignment was divided into two phases, and the first phase dealt with a risk assessment of the wind farms' possible impact on aviation safety, regularity and capacity at Copenhagen Airport. The second phase comprised of preparation and implementation of the EIA process of the two wind farms.
Both phases were finalized with submission of the EIA reporting to the authorities by the end of 2020. Remaining work is related to the public consultation and permitting processes.
410MW capacity of wind farms
The Nordre Flint project is expected to comprise 16-40 turbines with an individual capacity of between 4-10MW. The total capacity would be up to 160MW.
The permitting process for Nordre Flint is not finalized.
The Aflandshage project is expected to comprise of 25-63 turbines, each with an individual capacity of 4-10MW. The total installed capacity would be up to 300MW.
HOFOR has chosen to apply for and obtained a permit for installing 26 large turbines with a height of up to 220 meters and a total installed capacity of up to 286 MW.
Risk assessment of OWFs’ effects on Copenhagen Airport
The risk assessment was carried out in a collaboration between Copenhagen Airport and Naviair, HOFOR, Terma, NATS, and NIRAS and in coordination with the Danish Energy Agency and the Danish Transport Authority.
NIRAS facilitated the process and collected the documentation of the assessment.
NIRAS’s EIA seeks to diminish environmental impacts of wind farms
Following the risk assessment, NIRAS carried out the environmental impact assessments (EIA) to document the impacts of the proposed projects. The overall goal of environmental assessments is to work towards avoiding or mitigating as many impacts as possible, so the wind parks will be constructed with as little effect on the surrounding environment as possible.
NIRAS was project manager on the EIA, and coordinated all parts of the complex task with the client, authorities, stakeholders and the eight sub-contractors. Furthermore, NIRAS was also responsible for quality assurance and commenting on all background reports from the sub-contractors, as well as for management of resources, time and quality.
The topics of the EIA
The EIA’s addresses a long series of topics which comprise coastal morphology, sediment and water quality, including field surveys, dumping of dredged sediment, hydrographic conditions, and seabed types. The surveys include flora and fauna, fish and fisheries, which also involves interviews with fishermen, as well as surveys of marine mammals, birds and bats.
The task includes extensive field surveys, marine and terrestrial archeology, navigational safety, radars and radio communication lines, and air traffic.
The EIA also covers landscape and cultural heritage as well as visual impacts, including extensive visualisations from 31 photo locations along the Swedish and Danish coast as well as planning and land use, population and human beings, material assets, resource efficiency and socio-economics.
Other topics covered by the assessment include underwater noise and airborne noise, including extensive modelling of noise emissions both in air and underwater, air emissions and climate, geophysical mapping of the seabed and UXO studies.
Effects on Natura 2000 sites in Denmark and Sweden
The EIA includes effects on Natura 2000 sites in Denmark and Sweden and on Annex IV species, and possible effects on land, waste production, surface water discharge, impact on groundwater, soil contamination and material consumption.
As part of the EIA, NIRAS performs calculations of the levels of external and underwater noise both during construction and in relation to the operation phase, as well as modeling of sediment dispersion during the construction phase.
The assessments include impacts from the projects construction, operation and decommissioning phases and for all aspects defined in EU EIA-directive including cumulative effects and cross border effects and a ESPOO process/consultation.
Marine mammals and birds
The EIA’s assessments on mammals were based on existing knowledge on occurrence and distribution of marine mammals in the area.
In addition, observations of mammals were registered within and in the vicinity of the wind farm areas during eight flight counts of birds from October 2019 to September 2020.
Observations of mammals during the flight counts were used to support the conclusions regarding the occurrence of marine mammals and their use of the area.
The studies on birds included two years of field studies carried out by DCE to assess the potential impacts, i.e. displacement, barrier effects and collision risks. This was done using a combination of visual observations, 3D-tracking by laser range finder and radar-based monitoring.
By these means, data on the migration volume and flight altitude distribution were collected to obtain estimates of species-specific collision mortality from the use of advanced collision risk models.
The degree of potential displacement of waterbirds from the two wind farms was assessed by means of aerial bird counts, using the Distance Sampling line transect method.
The survey aircraft operates along pre-defined transect lines, and observers record birds on either side of the aircraft, strictly following a specified sampling protocol.
The method allows for an estimation of total numbers of relevant bird species within the study area. In other projects, spatial models provided a surface-covering estimation of density at a fine geographical scale.
From evaluations of displacement effects of Long-tailed Duck at the Nysted, Rødsand wind farm site and Common Scoter at the Horns Rev 1 and Horns Rev 2 wind farms, the degree of displacement could be established. Using this information in the Øresund project, a species-specific displacement assessment could be performed.
Subcontractors on the EIA
NIRAS used the following subcontractors to carry out the different tasks of the environmental impact assessments:
- DCE - Danish Centre For Environment And Energy
Migratory and resting birds and bats
Geophysical mapping of seabed and UXO studies
Seabed inspections, benthic flora and fauna
- Profus Naturrådning
Field studies migratory birds and resting birds
- Krog Consult
Fisheries and interviews of fishermen
- SEMCO Maritime
Technical descriptions of electrical grid connections offshore and onshore
NIRAS performs all other studies, background reports and the preparation of environmental reports.