Burbo Offshore Wind Farm is a twenty-five turbine, 90MW development located in Liverpool Bay approximately 6km from the coastlines of Wirral, Crosby and Liverpool. A licence (31864/07/0) was issued under the Food and Environment Protection Act (FEPA) to the wind farm developer, SeaScape Energy Ltd, which allows them to construct and operate the wind farm. The licence conditions include a requirement to monitor seabed sediments and invertebrate communities in and around the wind farm to allow the Licensing Authority (Marine and Fisheries Agency) to consider: if any action may be required to mitigate or correct any adverse effects which may be identified.’’ The benthic (seabed) monitoring programme consists of surveys by grab sampling and beam trawling (the latter providing information on demersal fish as well as epibenthic invertebrates and being reported separately). The benthic survey programme has been undertaken by Centre for Marine and Coastal Studies Ltd (CMACS) on behalf of SeaScape. The programme commenced with baseline (pre-construction) surveys in autumn 2005. The report in this series presents the results of the benthic grabs carried out in autumn 2009, more than two years after completion of major construction activities, and considers results of all four surveys (baseline, during construction and two post-construction) in relation to the potential effects of wind farm construction and operation on benthic environmental receptors.