KRIEGERS FLAK OWF GEOPHYSICAL SURVEY ... - Energinet.dk

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KRIEGERS FLAK OWF GEOPHYSICAL SURVEY RESULTS LIST OF ABBREVIATION BAT Bathymetry BKS Backscatter BLK Data Blanking area (Hazard) C Cretaceous Chalk CAD Computer Aided Design Ci Cretaceous Internal Reflector DBS Depth Below Seabed DVR90 Danish Vertical Reference 1990 EEZ Exclusive economic zone ELV Elevation FT Flow Till GEUS Geological Survey of Denmark and Greenland HAZ Hazard HF Holocene Freshwater HM1 Holocene Marine 1 HM2i Internal reflector within underlying Holocene Marine 2 HM2 Holocene Marine 2 - Undistinguishable base HM2+3 Holocene Marine 2 and 3 Hz Hertz IHO 5E 1a IHO Standards for Hydrographic Surveys (5 th Edition, 2008), Special Publication No. 44, 1a order survey KF Kriegers Flak KHz Kilohertz Km Kilometre KMS The Danish National Survey and Cadastre KP Kilometer Point LT Lower Till M Metre MBES Multibeam Echo Sounder MV Motor Vessel nT Nano Teslas QA/QC Quality Assurance / Quality Control OWF Offshore Wind Farm SBF Sea Bed Features SBP Sub Bottom Profiler SVP Sound Velocity Profile UT Upper Till TRK Track TWTT Two Way Travel Time UTC Co-ordinated Universal Time UTi Intermittent Internal horizon within Upper Till unit UTM Universal Transverse Mercator WGS84 World Geodetic System 1984 KF_OWF_Geophysical_Survey_Results_v4.docx
KRIEGERS FLAK OWF GEOPHYSICAL SURVEY RESULTS 1 1. SUMMARY A full suite of hydrographic and geophysical seabed surveys have been conducted across the entire Kriegers Flak Offshore Wind Farm (KF OWF) site. Although the geophysical pre-investigation area encompasses areas that not all will be subject for KF OWF development, including for example a sand abstraction area in the central part of the site, the geophysical survey area will from hereon in the report be referenced as the KF OWF site. Variations in seabed morphology can be observed from the bathymetric and side scan sonar datasets. The seabed sediment type has been established from the hydrographic and geophysical records, ground truthed by a series of grab samples. Infrastructure and seabed obstructions have been identified using all of the available datasets, one cable and three wrecks have been identified in the area. In addition a number of boulders have been observed. The water depths across the site range from 12m in the central and north eastern section of the site deepening at the perimeter of the site to a maximum depth of 33m in the far south of the site. The seabed surface is dominated by sand, with till exposures in the eastern and western part. The sub-bottom geology has been interpreted, and a geological model for the area has been established, which fits the dataset and all available other information examined. The major geological units identified at Kriegers Flak OWF are summarised in Table 1-1. The depths are derived assuming a constant acoustic velocity in the sediments of 1,900 m/sec. Table 1-1 Identified Geological Units Unit Description Depth to Base (m below seabed) Holocene Marine 1 (HM1) Blanket cover of loose fine-medium sand 0-2 Holocene Marine 2 (HM2) Loose fine-medium sand, showing progradation to the west 0-8 Holocene Marine 3 (HM3) Fine-medium sand within a spit, likely to be more compacted than HM1 and HM2 0-11 Flow Till (FT) Soft sands, clay and boulders less consolidated than the underlying tills from which they derive 0-15 Upper Till (UT) Diamict of predominantly clay with gravel, cobbles and boulders but also occurrences of silt and sand 0–26 Lower Till (LT) Diamict of predominantly clay with gravel, cobbles and numerous boulders 0-100 Cretaceous Chalk (C) Chalk Undetected KF_OWF_Geophysical_Survey_Results_v4.docx
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