According to the Marine Facilities Ordinance (SeeAnlV), the Federal Maritime and Hydrographic Agency (BSH) is responsible for the licensing of offshore wind farms in the German exclusive economic zone (EEZ). Within the scope of licensing procedures for offshore installations it is necessary to analyse to what extent noise caused by the construction, operation and decommissioning of wind turbines has an impact on the marine environment.
According to the Environmental Impact Assessment Act (UVPG), it is obligatory to carry out an environmental impact assessment (UVP) for offshore wind farms. During the application process, the applicant performs an environmental impact study (UVS) where, among others, the possible effects of noise emission on the marine environment are described and assessed.
Condition 14 of a BSH license prescribes regular measures to determine and minimize waterborne sound. Measurements of waterborne sound during noisy work phases (e.g. impact pile driving) have to be carried out at defined distances and have to be documented. Protective and noise mitigating measures have to be verified during implementation for their efficiency by means of sound measurements. The results have to be documented and reported to the licensing authority.
However, worldwide validated empirical values concerning underwater noise caused by the construction and operation of offshore wind farms are missing, as there are no standardized measuring methods and no validated sound propagation models.
The temporal and spatial scope of the acoustic investigations is described in the Standard for the Environmental Impact Assessment (StUK3 2007, ). For this purpose, underwater sound measurements have to be carried out prior to construction, during construction and during operation. First results from acoustic investigations at the alpha ventus test field (itap 2011, ), from offshore research platforms and measuring masts have provided the basic information to revise the present measuring procedure according to StUK and to summarize the results in a detailed measuring instruction. The measuring instruction is part of the StUK and specified in the appendix.
The following specification describes the general procedure for underwater sound measurements connected with the construction and operation of offshore wind farms. It covers the four phases of licensing and enforcement procedures of offshore installations in the German EEZ:
a) Baseline study - preliminary investigations
b) Construction phase
c) Operation phase
d) Decommissioning phase.
Deviations from the procedure described in the following, which are justified by projectspecific or site-specific needs, might be agreed upon with the licensing authority.
The institutions in charge of the sound measurements must hold appropriate qualifications for the execution of sound and vibration measurements, which can be obtained by an accreditation according to DIN EN ISO/IEC 17025 or a comparable qualification. The required certifications must be provided by the respective institutions.