Abstract
On the instructions of Npower Renewables, Osiris Projects were commissioned to carry out hydrographic survey works within the proposed turbine area of the Rhyl Flats offshore wind farm development site in Liverpool Bay. The overall primary objective of the surveys was to map bathymetry, sub-bottom profiling and seabed features, including any magnetic anomalies and sonar contacts.
The purposes of this report were to directly compare both the bathymetry and side scan sonar data sets from two surveys carried out in 2005 and 2006, in order to evaluate the
general movement of mobile sediments across the site. This scope was extended when bathymetric data from the 2001 survey, carried out by Fugro Ltd, was also made available for comparison.
Osiris Projects carried out the first of their surveys during August 2005, with data collected at a survey line spacing of 50m. Data acquisition for the 2006 survey was carried out during the period 14th March to 5th April 2006. This survey involved running a series of additional lines, run parallel to, but offset 10m south from, the 2005 survey lines. All processed and interpreted data from the 2006 survey is separately presented in Osiris Projects Report No C6005b.
Data acquisition for the 2005 and 2006 surveys was undertaken using MV 'Barinthus', a purpose built survey vessel owned and operated by Ocean Marine Services Limited.
All positions are expressed in UTM Zone 30N, 3°W coordinates, throughout this report.