6 
Part A - Introduction 
2 General 
Erecting structures to harvest of offshore wind energy in the EEZ is one of those construction 
measures with a high level of difficulty from a geotechnical standpoint. The ground conditions 
play a decisive role alongside aspects regarding construction and load. Contrary to widely- 
held opinion, the sea floor in the EEZ of the North Sea and the Baltic Sea does not comprise 
of a homogeneous soil with depth and area, but can indeed be extremely heterogeneous on a 
regional and even local scale. In contrast to constructing with steel or concrete, the material 
properties of the soil all together cannot be adapted for the structure. For this reason, precise 
knowledge of the geological conditions and geotechnical characteristics of the subsurface at 
the actual sites of all components of an offshore wind farm is of great importance to ensure 
that construction of an offshore wind farm takes place successfully. 
The geological makeup of the seabed as a model is the basis for subsequent site investiga 
tions, planning and construction. Areas can be demarcated based on the results of a prelimi 
nary geological investigation, the expense of geotechnical investigations can be planned and 
in some circumstances alternative sites can be identified for offshore structures in seas where 
the seabed consists of localised areas with unsuitable ground conditions. 
The design of the foundation structure demands sufficient detailed knowledge of the ground 
conditions, geotechnical characteristics and the parameters on the site of each structure. For 
this reason ground investigations must always be carried out with a scope that provides all 
characteristics of the respective ground conditions can be established in good time before 
construction of the structure. Geotechnical site investigations and evaluations must therefore 
be carried out by qualified experts. 
The current guideline contains a ground investigation and study programme graduated de 
pending on type and scope for planning and erecting offshore wind energy structures. This 
programme is coordinated with the requirements for individual phases as part of Standard 
Design and establishes a minimum coverage. 
The term geotechnical survey covers field site investigations. The generic term geotechnical 
survey and investigation also includes the laboratory tests as well as the expert assessments 
and evaluations resulting from them. 
From a geotechnical viewpoint, the processing steps set out in Table 1 can be distinguished 
including all necessary professional development and documentation according to chrono 
logical order.