Emu Wraps Up London Array Survey
With the return of their final survey vessel to Ramsgate, Emu Limited reports the successful completion of an eleven-month series of geophysical surveys for the London Array Wind Farm. Objectives included providing accurate spot-heights for turbine locations, providing pre-construction baselines, environmental assessments and the identification of possible wreck sites, pipelines, seabed obstructions and other ferrous objects including UXO around the site.
Emu were commissioned to undertake a number of pre-constructionsurveys of the wind farm site and export cable route, to be sited in the outerThames Estuary some 20km from the Kent and Essex coasts.
For the final engineering survey Emu used their high resolutionUXO/debris detection system, developed in 2009, which has since collected over35,000 km of data. The Emu system offers developers maximum freedom with cablerouteing and turbine siting using high precision data, which provides accuratelocation of dangers. Of benefit to London Array, the system enables large areasto be surveyed in relatively short periods.
During their London Array wind farm geophysical survey, EmuLimited discovered a wreck on the seabed in the approaches to Foulger’s Gatchannel in the Thames estuary.
The wreck, which was previously undiscovered despite havingbeen passed over in previous years by other surveys, is 45m long and lies in4.5m of water. The hatch coamings and thwarts of the ship are preserved and canbe clearly seen on the side-scan and swath sonar imagery gathered by EmuLimited. The wreck’s identity and the circumstances surrounding its loss arenot yet known.
Emu’s RV Discoverylocated the wreck, which lies just east of part of the planned export cableroute. As a result a new Archaeological Avoidance Zone has been put in place.The cable will be re-routed to further west to avoid this zone and will requireadditional surveys of the new route. The anchor patterns for the installationvessels may also require some amendment.
Four vessels were employed during the survey, the Emuvessels Emu Surveyor, RV Discovery and Ceejay and the chartered NabCat II.
The client representatives have reported that they wereimpressed with the enthusiasm and professional approach of Emu’s staff and havebeen very satisfied with the outcome.
