800dcf2057cbfb471c713d0840d4371a eng series ABP Marine Environmental Research Ltd Data Manager Southampton SO14 2AQ United Kingdom enquiries@abpmer.co.uk http://www.abpmer.co.uk pointOfContact 2021-08-18 MEDIN Discovery metadata standard 2.3.8 urn:ogc:def:crs:EPSG::32631 2021, Fugro, Sheringham Shoal Offshore Wind Farm, Seabed Monitoring Survey Comparison 2021-05-20 publication 201193-R004 Fugro was commissioned by Equinor (U.K), to undertake monitoring surveys of the Sheringham Shoal Offshore Wind Farm, export cable route, and transit route.This report provides a comparison of the results from six surveys carried out by Fugro: the 2008 pre-installation survey, winter 2013, winter 2014, winter 2015, winter 2018 and winter 2020 monitoring surveys. The 2008 survey was a full pre-construction geophysical and hydrographic survey and provided a baseline for an assessment of changes that may have resulted from the construction of the Wind Farm infrastructure. The 2013, 2014, 2015 surveys were carried out in order to meet the requirements for site monitoring as set out in MMO Licence L/2011/00153/16. The 2018 and 2020 surveys were undertaken as part of an ongoing program of preventative maintenance. Following an assessment of data collected in 2008, 2013, 2014, 2015, 2018 and 2020 the following summary conclusions have been made: - The most prominent natural seabed change since 2008 was associated with the movement of large dune bedforms in the south-east of the Wind Farm site. The largest seabed change was associated with a reduction in depths of up to 3.91 m (accretion) and increase in depths of -3.37 m (erosion). - Since 2008 a total of 19 WTG locations exhibited a seabed deepening (erosion) of over 0.5 m within a radius of 25 m from the monopiles and the surrounding rock armour. These corresponded to WTG locations A3, D5, E5, F5, F6, F7, G5, G6, G8, H4, H5, H6, H8, I6, I7, I8, J7, J8 and K8. - Since 2018 seven WTG locations (E5, F6, G6, H6, I6, J8, K8) exhibited a seabed deepening (erosion) ranging from 0.4 m and 0.9 m. Additional 12 WTG locations exhibited not significant erosion ( less than 0.3 m); these corresponded to A3, D5, F5, F7, G5, G8, H4, H5, H8, I7, I8 and J7. A further WTG location (A7) is reported to have undergone net accretion. - Within the Cromer Shoal Marine Conservation Zone (MCZ) on the export cable route one minor change in depth was seen within the trenching area since the last survey was conducted in 2018, this represented an area of erosion between 0.2 to 0.7 m. -One exposure on the eastern export cable route (B) was identified in both the 2018 and 2020 surveys; this exposure decreased from 14.9 m to 9.6 m since 2018. - Fifteen exposures were identified in the main array area in the 2020 survey, of which nine were new exposures not seen in 2018. Four exposures exhibited evidence of freespan. - Eight cable exposures were found adjacent to 8 WTG locations, all located in an area of mobile seabed sediment waveforms. These corresponded to WTG locations K8, J8, J7, I7, H6, G6, F6 and G5. Those adjacent to WTG locations J8 and G6 exhibited evidence of freespan. - Where no construction activity, trenching or sediment transport was observed, bathymetric differences were generally less than +/-0.5 m between all bathymetry surveys, as demonstrated by differences recorded at the datum square Fugro +44 (0)2392 205500 Victory House,Trafalgar Wharf (Unit 16), The Sawmills, Durley Portsmouth PO6 4PX Unknown www.fugro.com originator The Crown Estate +44 020 7851 5000 1 St James's Market London SW1Y 4AH United Kingdom enquiries@thecrownestate.co.uk www.thecrownestate.co.uk custodian notPlanned Documents Marine Environmental Data and Information Network Elevation Geology Hydrography Land cover Oceanographic geographical features GEMET - INSPIRE themes, version 1.0 2008-01-06 revision Bathymetry and Elevation Sound velocity and travel time in the water column Side-scan sonar SeaDataNet P021 parameter discovery vocabulary 2009-11-16 revision Construction monitoring Pre-Construction monitoring Post-Construction monitoring The Crown Estate Renewable Energy Development Phases 2012-05-15 revision Renewable Energy Lease area Offshore Cable Corridor The Crown Estate Renewable Energy Development Areas 2012-05-15 revision otherRestrictions Kept confidential until owner and distributor agree to give public access https://www.marinedataexchange.co.uk/content/info/faq 0.25 eng elevation geoscientificInformation oceans 0.8285 1.2316 52.9487 53.1828 2008-03-01 2020-12-29 series MEDIN data guideline for multibeam echosounder (MBES) data 2012-04-30 publication See the referenced specification true verall, the quality of the MBES data acquired by Fugro on the Sheringham Shoal Wind Farm improved from the 2008 baseline survey to the 2013, 2014, 2015, 2018 and 2020 monitoring surveys. All survey data collected exceeded the specified quality requirements. The improvement in data quality over this time period was due to continued improvements in MBES data resolution and positioning accuracy, alongside refinements in the processing methodology. Fewer motion artefacts were present in data collected since 2013, which resulted in a cleaner data set and improved resolution of fine scale features (such as seabed dunes less than 0.1 metre high). In addition, this also ensured that the bathymetric difference grids were more precise. This was apparent in areas where no movement of the seafloor had occurred. In these regions’ vertical differences between all three surveys were less than +/-0.2 m. Therefore, changes of less than 0.3 m were not considered significant, when assessing areas of erosion or accretion. The SSS data were acquired using the same equipment and employed the same processing methodology each year and therefore did not exhibit any significant changes; although some of the interpretation criteria differed between surveys due to different project objectives (as detailed in Sections 1.1 and 3.2.1). https://www.marinedataexchange.co.uk/details/3493/summary A link to the web service or dataset. https://www.marinedataexchange.co.uk A link to the general host site.