Seabed survey contractor Bibby HydroMap completed geophysical, geotechnical, benthic and land survey operations along the route from mainland Scotland to the Isle of Lewis, on behalf of client SHE Transmission.
Three vessels were used during the survey; 27.5m DP1 Bibby Tethra for offshore geophysics, geotechnical sampling and benthic operations, 14m MV Proteus for nearshore geophysics and the 9m RIB Cougar to ensure overlap between the inshore and land survey.
Bibby Tethra. Photo courtesy: Bibby Hydromap
Over 1000 line km of survey data were acquired with Bibby Tethra, using the vessel’s newly installed dual head Kongsberg EM2040-4, with the towed Edgetech 4200 side scan sonar and Geometrics magnetometer positioned using the new Sonadyne Mini-Ranger 2 USBL. Shallow sub-bottom profiler data were also acquired using the vessel’s hull-mounted Applied Acoustics pinger. Despite the challenging environmental conditions, geophysical operations were completed ahead of schedule yielding high quality data.
Bibby Tethra’s scope of work also included conducting over 80 CPTs and vibrocores, in addition to 26 benthic drop down video and grab sampling stations.
Bibby HydroMap Project Manager Simon Baldwin comments:
"Operating between the North-West highlands and the Western Isles always presents a number of challenges for survey operations including highly variable water depths and seabed gradients, the restricted maneuverability associated with working within the stunning sea lochs, and also the general remote nature of the survey location in terms of logistics and support. In spite of all of these testing conditions it was incredibly heartening to be able to carry out the integrated, multidisciplinary, multi-vessel survey safely and within a swift timescale. Our vessels are fast gaining a deep working knowledge of this area following years of work supporting cable laying operations in this region and I shall certainly be on the long list of people wishing to be involved in the next project in this amazing area of the UK’’“
SHE Transmission representative Neil Anderson comments:
“SHE Transmission is continuing to progress the development of the Western Isles connection with a view of preparing and submitting a needs case to the industry regulator Ofgem in spring 2017. To progress the projects development, SHE Transmission engaged Bibby Hydromap to undertake a marine survey and gave precise information and knowledge of the environment that will form part of the electrical connection from mainland Scotland to Western Isles”.