Teil B - Minimum Requirements on geological survey 
17 
Table 3: Requirements of echo-sounding measurements. 
Geological survey 
Inspection 
Objectives 
• Detection of local depth changes 
(potential scour) 
Scope 
• Full coverage 
• In the local surroundings of the founda 
tion elements of the offshore structures 
Timing 
• Once 
• In the initial years after completion 
check once per year, early on in the year 
Method 
• Multi-beam echo sounder (MBES) 
• Positioning better than 5 m + 5 % of 
water depth as well as 
• accuracy for reduced depths in accord 
ance with IHO (2008) for Order 1 b surveys 
• Multi-beam echo sounder (MBES) 
• Positioning better than 5 m + 5 % of 
water depth as well as 
• accuracy for reduced depths in accord 
ance with IHO (2008) for Order 1 a surveys 
Presentation 
of results 
• Bathymetric map of the areas surveyed 
• Water depths must be adjusted for wa 
ter sound propagation and illustrated 
based on CD (LAT) (Tidal correction) 
• Data must also be submitted in digital 
format and with sufficient supporting 
documentation 
• Bathymetric map of the areas meas 
ured 
• Water depths must be adjusted for wa 
ter sound propagation and illustrated 
based on CD (LAT) (Tidal correction) 
• Data must also be submitted in digital 
format and with sufficient supporting 
documentation 
Table 4: Requirements of side scan sonar (SSS) investigations. 
Geological survey 
Inspection 
Objectives 
• Summary of the present sediment 
types and structures. 
• Validation and calibration of the find 
ings by means of ground truthing. 
• Detecting erosion areas, scour or ob 
stacles. 
• Validation and calibration of the find 
ings by means of ground truthing. 
Scope 
• Sections in accordance with seismic 
measurements or extensively over the 
offshore construction site 
• Extensively within areas with heteroge 
neous sediment cover 
• In the local surroundings of the founda 
tion elements of the offshore structures 
Timing 
• Once 
• In the initial years after completion 
check once per year, early on in the year 
Method 
• Frequency of 100 kHz or higher 
• Measured area is a maximum of 2 x 
100 m 
• Recognition of objects > 1 m in grid 
spacing* 
• Digital recording 
• Cruising speed max. 4 kn, provided that 
the equipment used does not demon 
strably allow for higher cruising speeds 
• Positioning of the equipment is better 
than 10 m 
• Frequency of 100 kHz or higher 
• Measured area is a maximum of 
2 x 75 m 
• Recognition of objects > 1 m in grid 
spacing 
• Digital recording 
• Cruising speed max. 4 kn 
• Positioning of the equipment is better 
than 10 m 
Presentation 
of results 
• Digital SSS mosaic of the sections (hor 
izontal resolution from 0.5 m) 
• Map with interpretations of the side 
scan sonar sections 
• Data must also be submitted in digital 
format and with sufficient supporting 
documentation (internal format) 
• Digital SSS mosaic of the sections (hor 
izontal resolution from 0.5 m) 
• Map with interpretations of the side 
scan sonar sections 
• Data must also be submitted in digital 
format and with sufficient supporting 
documentation (internal format) 
2 modelled on IHO (2008) for Special Order Surveys.