JUNE/JULY 2013 | £5.25 - Wind Energy Network

scour featurescour featureEffective scourprotectionTeesside Offshore Wind farmscour protection projectMarske Site Services (MSS) has justcompleted specialist sea bed protectionwork on the Teesside offshore wind farm.EDF Energy Renewables appointed MSSof Stokesley, near Middlesbrough, to carryout the ‘scour protection’ of the steelmonopile foundations located 1.5km offthe coast of Redcar in the Tees bay.Project detailThe specialist underwater engineeringwork involved the placement of large netsfilled with loose stone around the baseof each turbine to offset any removal ofseabed sediment caused by wave andtidal movement.The Nylon and polyester filter bag is madefrom 61% recycled bottles and filledwith carburised limestone, to provide astable yet flexible structure that requiresno seabed levelling or dredging prior toinstallation.Environmentally friendlyproductThe product is environmentally friendlyand has been certified by FEPA (Food& Environment Protection Agency) andDEFRA (Department of Environment,Fisheries & Rural Affairs) and workseffectively to stabilise the velocity of flowaround sub surface structures preventingsuction and scour for ‘life.’The filter units create a porous structurethat is positioned on the sea bed toprotect it from the effects of scouring,whilst also allowing fish to circulate andcreating a new habitat for shellfish andother marine life.Installation techniqueFor this project, MSS used their uniquePatent-Applied installation technique.The company’s diverless installationmethodology is a viable and cost-effectivesolution for existing foundations withoutprotection where scour has been identified,or for foundations where the protection hasbeen washed away or has failed.For the Teesside project they installed amatrix of 4-tonne & 8-tonne capacity filterbags to provide coverage, flexibility andstability. It was important that the bagswere laid in a specific configuration, whichis due to the process which incorporatesvisual sonar imaging and a diverless remoterelease mechanism to ensure the bagswere positioned safely and accurately.Specialist subsea constructionvesselThe work was undertaken from the 7,000teDP2 Maersk Responder, a specialist subseaconstruction vessel which, due to the stableplatform and the high capacity it provides,enables this work to be continued aroundthe clock from a single vessel.The MSS Engineering team mobilised thevessel, coming up with a unique solutionfor safely transporting an extra-large loadof filter bags, which, combined with a 50%improvement in the time taken to completeeach monopile, resulted in the ScourProtection Project team completing theproject both safely and ahead of schedule.Team effortOn completion of the work the ProjectManager of EDF, Tim Bland, thanked theteam for the “brilliantly executed job.”John McCullagh, Director of MSS, said:“MSS is a Teesside company with aninternational business base; it’s great tosecure such a project on our doorstep!We employ many Teesside people andI would like to thank the whole team forbringing in this project safely, accuratelyand ahead of schedule.”Marske Site Services Ltdwww.marskesiteservices.co.uk3D visualisation technologyUnlike oil & gas, the renewablessector is still at a stage where largeparts of the supply chain, and welldefinedprocedures and practices, arenot fully developed.This fact represents an opportunityfor new technologies and innovativeapproaches – such as the 3D visualisationtechnology outlined here – to find theirplace and become part of the standardprocedure for effective operation &maintenance procedures in the futureImportant factorsADUS DeepOcean has engaged with anumber of UK windfarm operators in orderto understand their ongoing inspectionrequirements. There is an essential needto identify and monitor a number ofimportant factors which include…ScourAside from the danger of unsupportedcables, scour affects foundation stability.This technology effectively maps scour andpresents it in a fully metrical 3D visualisationfor a greater understanding of the problem.More importantly though this allowsdetailed monitoring over time, bycomparing successive datasets, andprovides the ability to accurately measurethe depth and overall dimensions of scouras well as the volume of material removed.of Mexico, and more recently, the strickencruise ship Costa Concordia in Italy andthe cargo ship Rena which sunk off thecoast of New Zealand.Building on its success, ADUS hasrecently begun to successfully deployits know-how and technologies in theoffshore wind and oil & gas markets,where it can be used to provide highquality 3D images of subsea structuressuch as offshore facilities, wind turbinefoundations and seabed architecture.ADUS DeepOceanwww.deepocean.noClick to view more info• Scour around the base of monopiles• Cable exposure on the seafloor• Movement of sand waves across thesite• Cable freespan• Cable tension• Cable bend radiusMonitoringThis 3D visualisation technology is directlyapplicable for the effective monitoringof these factors and can add value byincreasing opportunity, speed & qualityof data acquisition, and reducing use ofdivers and ROVs, whose tasks can involvethe manual measurement of these factors.The use of divers in such operations isoften problematic with down time causedby weather, but also the requirement onlyto dive during slack water periods.About ADUS DeepOceanADUS DeepOcean Ltd was formedin 2013 following the acquisition of a50% interest in ADUS by DeepOceangroup. Formerly Advanced UnderwaterSurveys Ltd, ADUS was originally a spinout from the University of St Andrewsand Dundee University and has rapidlyacquired a global reputation in the marinesalvage market for its stunning subsea 3Dvisualisations.The company is known for such highprofile work as the survey of the wreck ofthe oil rig Deepwater Horizon in the Gulf50 www.windenergynetwork.co.ukwww.windenergynetwork.co.uk 51