Horizon Geosciences has recently used its 200kN Seabed CPT system to complete a geotechnical site investigation for Vattenfall’s 400MW Horns Rev 3 offshore wind farm in the Danish part of the North Sea.
Horizon’s scope of work centered around turbine locations and infield cable routes. The programme of work included downhole sampling and CPT testing, seismic CPT testing, pressuremeter testing, P-S Logging, vibrocoring and seabed CPTs.
“Works conducted included 7 combined geotechnical sampling boreholes. Seabed CPT testing in excess of 1300m was completed,” Wolfekart Semm, Project Manager for Vattenfall, said.
The 200kN Seabed CPT System can be deployed from any DP1 or DP2 vessel. The Horizon Geobay was assigned in this case due to her full geophysical and geotechnical spreads, containerized laboratory and capacity to operate in shallower waters.
“The Horizon Geobay was used as a platform throughout the whole campaign and has proven to be a very capable DP2 vessel, especially as shallow water conditions were prevalent. All operations were conducted safely and in-line with HSE requirements with a very positive HSE attitude and awareness of safety shown by the entire crew,” Semm said.
Horizon’s digital CPT System is designed to achieve a continuous profile to depths in excess of 40m into the ground.
“Building an accurate ground model is crucial to the development of offshore wind farms, therefore a high volume of quality CPT data is needed, often within tight timescales,” Senior Project Manager for Horizon Geosciences Limited, John Cudden, said.
”This is where Horizon’s 200kN CPT can surpass traditional drilling expectations in terms of production and cost. Coupled with the ability to conduct seismic CPT tests with this seabed system, tied in to pressuremeter and borehole logging data from adjacent boreholes, we provide the data for the full determination of both lateral and horizontal engineering properties across the site.”
Horns Rev 3 is situated off the west coast of Denmark, and is expected to generate green power for some 450,000 households when fully operational. The first turbines at Horns Rev 3 are expected to be connected in 2017.