2011, ABPmerCMACS, Burbo Bank Offshore Wind Farm, Metocean Survey to address Outstanding Licence Conditions

Description

This series presents the results of recent metocean survey work undertaken at the Burbo Bank 
Offshore Wind Farm, designed to address two outstanding licensing conditions: 
1. Tidal Model Validation: There were concerns regarding the original tidal current data collected 
at the site and used to inform and validate the tidal model used in the original EIA study. To 
revalidate the model, new tidal current profile survey data were collected and compared to the 
model output. The results confirm that the original tidal model performs well in predicting tidal 
current speed and direction at the site. 
2. Tidal Wake Validation: The original EIA study included the conservative prediction of tidal 
wake effects from an array of 30 turbines on 4m monopiles and the subsequent effect on 
regional sediment transport rates and pathways. To validate the accuracy of the tidal wake 
predictions by the model, a field survey was designed and undertaken to measure and map the 
gross flow properties of the tidal wake associated with the BB27 foundation (a 4.7m diameter 
monopile with rip-rap scour protection). 
The results of the wake survey compared closely to the modelled wake in terms of time mean flow 
properties but also differed somewhat in terms of the lateral extent of the wake in the very near-field 
(<200m downstream, a limitation of the model associated with mesh resolution) and the 
presence/absence of locally elevated turbulence (also a limitation of all such regional scale modelling 
tools). The implications of elevated levels of turbulence being observed in the field but not being 
present in the model are discussed in relation to the predicted patterns of sediment transport, 
suggesting that, on balance, the model correctly estimates the effect on sediment transport.