The purpose of this study is to inform a variation application by Westermost Rough Ltd. for the drill arisings disposal strategy (Marine Licence LA/2013/00309). The reason for the variation is that Westermost Rough Ltd. proposes that whilst the project does not expect to drill on more than a maximum of five foundation locations during installation works for the Westermost Offshore Wind Farm, the project requires flexibility to drill any foundation should it be required as a contingency. The previous study (and this one) assumed all of the monopile would be drilled (rather than sections that cannot be driven through) and so is worst case. This study assumes surface release (so modelling is necessary) unlike the last one which released near bed and so could use the monitoring results of near bed release at Lynn and Inner Dowsing wind farm. The report within this series provides an updated assessment of potential physical impact of drill arisings for the five already assessed and the other 30 foundations in the offshore wind farm. The report provides an assessment for the complete array of foundations. The desk based methodology in HR Wallingford (2013) has been combined with results from site specific numerical modelling of plume dispersion and deposition (Appendix A). The results are used to evaluate the potential physical impact of drill arisings on the Annex I stony reef habitat found within the Westermost Rough Offshore Wind Farm.
2014, HR Wallingford, Westermost Rough, Drill Cuttings Assessment for the Array