15


Should little or no change to the level of the trench be observed between surveys then it is suggested that the frequency of monitoring be reduced to once every five years.


7 16 Identification of Appropriate Thresholds


Remedial action should be considered in such instances where, if measured rates of seabed lowering were to continue, cable exposure may occur prior to the next period of monitoring.


8 17 Remediation Actions


Should the cable be at risk of becoming exposed or becoming a snagging hazard at the seabed during the operational phase of the project, one option available is to re- bury it using similar methods to those already described and assessed within the Environmental Statement for the initial trenching and burial process. Alternative methods of cable protection include mattressing, concrete casings and rock placement. These devices would be placed onto the seabed surface above the cable. Any such remedial works would be subject to a new Marine Licence and as such all relevant stakeholders would be consulted during the planning of such works to determine the most appropriate action.


9 References


BERR, (2008). Review of cabling techniques and environmental effects applicable to the offshore wind farm industry. Technical Report.


Burningham, H. and French, J. (2009). Seabed mobility in the greater Thames Estuary. The Crown Estate, 62 pages.


Emu, (2012). Cable Route Geophysical Survey for the East Anglia ONE Offshore Windfarm. Draft Report for East Anglia Offshore Wind Ltd, 12 March 2012, 59pp.


Environment Agency, (2013). Cross-shore and near-shore seabed profiles from Bawdsey. http://www.channelcoast.org/anglia/ Accessed on 3/07/13.


HR Wallingford, (2011). East Anglia Marine Aggregate Regional Environmental Assessment. HR Wallingford Report 6430.


Outline Bawdsey bed level monitoring and remediation strategy (V1)


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