esca guideline no
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ESCAGuidelineNo.6
TheProximityofOffshoreRenewableEnergyInstallations&SubmarineCableInfrastructureinUKWaters
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DocumentHistory
AnypartywishingtoproposeachangetothisdocumentshouldaddresstheproposedchangetotheChairoftheRenewablesandPowerCables(RPSG)SubgroupofTheEUROPEANSUBSEACABLESASSOCIATION(ESCA).TheRSGwillthenreviewtheproposedchangeandconsiderre-conveningtheTechnicalWorkingGroup("TWG")todiscusstheproposal.OncetheRSG(andTWG,ifappropriate)aresatisfied,theirfindingsandthereviseddocumentwillbepresentedto theESCAPlenaryandother respectivebodies forapproval.Onlywhenallpartieshaveapprovedthechangeswillthedocumentbere-issued.
Allchangestothisdocumentwillberecordedinthetrackingtablebelow.
IssueNo. Name Comments Date1 RSG InitialIssue Oct20032 RSG Revisiontoformat Sept20063 RSG Interimrevision–textandadded
diagramstoaccountforMultipleturbinearrays
Sept2010
4 RSG Majorrevisionandre-writewithcross-sectorinputviaaTWG
Aug2012
5 Secretary RebrandingtoESCA Mar2016
Thisdocumentistheresultofasuccessfulcollaborativeexerciseinvolvingawiderangeofindustry and stakeholder representatives. It is theproductof abestpractice approach tominimisingtheprospectoffuturedisputeswhilstmaximisingseabeddevelopmentthroughthe adoption of the principle of sharing the seabed in a manner that is both safe andsustainable.
Theauthorswould liketothankDECC,BIS/DCMS,MMO,MarineScotlandandOFGEMfortheirsupportintheprocessleadingtothegenerationofthisdocument.
Disclaimer
TheinformationcontainedinthisdocumenthasbeencompiledbytheRenewablesSub-Group("RSG")ofESCA,thisbeingthesuccessororganisationtoSUBSEACABLESUK(SCUK),whichsucceededtheUnitedKingdomCableProtectionCommittee("UKCPC").
This document is based upon the combined experience and knowledge of the submarinetelecommunication cable industry, theoffshore renewable energy industryandTheCrownEstate. It is published in good faith with the aims of promoting the highest standards ofconstruction, operability, reliability, maintainability and safety in the subsea cableenvironment.
Whilstwereasonablybelievetheinformationcontainedhereintobevalid,it isuptothosewhomayseektorelyonsuchinformation,tosatisfythemselvesastoitsaccuracy.ESCAandalltheothernamedassociationsandentitiesresponsiblefortheinformationcontainedinthisdocumentanditscompilationmakenowarrantiesastoitsaccuracyandcanacceptnoliability
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(direct or indirect) for any errors in the information or for any losses or other adverseconsequencesarisingfromitsadoption.
It is the intentionof this document togiveguidanceand to facilitatediscussionsbetweeneffectedparties,butitisnotintendedtoreplacesuchdiscussions,norisitintendedtorequireanyaffectedpartytobehaveinacertainwayorremovetherightofanysuchpartytotakeitsowncommercialdecisionsinrelationtoanyoftheissuesraisedinthisdocument.
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TableofContents1 DEFINITIONS&ABBREVIATIONS......................................................................5
2 EXECUTIVESUMMARY.....................................................................................6
3 SCOPEOFTHEGUIDELINE................................................................................7
4 INTRODUCTION...............................................................................................8
5 KEYFACTORSDETERMININGPROXIMITYLIMITS............................................10
6 STAKEHOLDERCONSULTATION......................................................................11
7 GUIDANCEFORINDICATIVESEPARATIONDISTANCES....................................12
8 PROCESSFORDETERMININGSITESPECIFICPROXIMITYLIMITS......................15
9 PROXIMITYAGREEMENT...............................................................................19
10 MULTIPLECABLECROSSINGSINCLOSEPROXIMITY........................................22
11 DISPUTERESOLUTIONPROCESS.....................................................................23
12 RECOMMENDEDCONSIDERATIONS,GUIDELINESANDREFERENCES..............25
13 ANNEXA-KEYFACTORSDETERMININGPROXIMITYLIMITS...........................25
14 ANNEXBSTAKEHOLDERCONSULTATION.......................................................33
15 ANNEXC–CHECKLISTFORISSUESTOBECONSIDEREDINASITESPECIFICRISKASSESSMENT...................................................................................................................38
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1 DEFINITIONS&ABBREVIATIONSALARP-AsLowAsReasonablyPracticable
BIS–DepartmentforBusiness,InnovationandSkills
DCMS–DepartmentforCulture,MediaandSport
COLREGS–ConventiononInternationalRegulationsforPreventingCollisionsatSea,London20 October 1972, (as enacted in the UK by TheMerchant Shipping (Distress Signals andPreventionofCollisions)Regulations1996
DECC–DepartmentforEnergyandClimateChange
Developer -AnentityundertakingmarinedevelopmentwithinUKEEZ/REZandTerritorialWaters
DOW–DepthOfWater
DP–DynamicPositioning
DPO–DynamicPositioningOperator
EIA–EnvironmentalImpactAssessment
ESCA–EuropeanSubseaCablesAssociation(formerlySCUKandUKCPC)
FEED–FrontEndEngineeringandDesign
HazardArea–ThatareacentredaroundanindividualOREIstructureadjacenttoasubmarinecable,whichreflectstheOREIstructure’sstatusasahazardforanyvesseloperatingonsaidcable.TheradiusoftheHazardAreashallbeagreedbasedonthelevelofrisktothevesselandthevessel’sowncapability.
HSE–HealthandSafetyExecutive
ICPC–InternationalCableProtectionCommittee
IPC–InfrastructurePlanningCommission
ISM–InternationalSafetyManagement
LARS–LaunchandRecoverySystem
MMO–MarineManagementOrganisation
MOU–MemorandumOfUnderstanding
NationalInfrastructureDirectorate–bodyreplacingtheIPCundertheLocalismAct
NM–NauticalMile(1.852km)
O&M–OperationsandMaintenance
OFGEM–OfficeofGasandElectricityMarkets
OREI–OffshoreRenewableEnergyInstallation
OWF – Offshore Wind Farm including associated structures such as Met Masts andSubstations
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REA–RenewableEnergyAssociation
ROV-RemotelyOperatedVehicle
RUK–RenewableUK
SCUK–SubseaCablesUK(formerlyUKCPC)
Stakeholder-AnentitywhoisaseabeduserorapartywithvestedinterestwithintheUKExclusiveEconomicZone
SubmarineCable-Anunderwatertelecommunicationorpowerorcontrolcable
TheCrownEstate-Theorganisation,establishedbyanActofParliament,whichmanagesthehereditaryestatesoftheCrownonbehalfoftheUK
TWG–crosssectorTechnicalWorkingGroup (comprisingrepresentatives fromESCA,RUK,REAandTheCrownEstate)
UNCLOS-UnitedNationsConventionontheLawoftheSea
WTG–WindTurbineGenerator
ZeroImpact-Adevelopment/activitythathasnoimpactuponaStakeholder.
2 EXECUTIVESUMMARYThisdocument(referredtoasthe"Guidelines")providesguidanceontheconsiderationsthatshould be given by all Stakeholders in the development of projects requiring proximityagreementsbetweenoffshorewindfarmprojectsandsubseacableprojectsinUKWaters.The Guidelines address installation and maintenance constraints related to wind farmstructures, associated cables and other submarine cables where such structures andsubmarinecableswilloccupyproximateareasofseabed.
TheGuidelinesdiscussinsection1someofthekeyfactorsdeterminingproximitylimitstobe taken into account in reaching proximity and crossing agreement. Further details areprovidedinAnnexA.
TheimportanceofearlyStakeholderconsultationshouldbeappreciatedattheoutsetanditisrecommendedthatthisisactionedasearlyaspossibleasinsection2andfurtherexpandedin Annex B. The location of existing seabed infrastructure within potential projectdevelopmentareascouldhaveasignificantimpactuponthelayoutorlocationofaprojectanditsdesign.DiscussionandStakeholderengagementareconsideredtobethecornerstonesofgeneratingthegreatestopportunitiesforasuccessfuloutcome.
TheGuidelinesarenotintendedtoprovideaprescriptivesolutiononproximitybut,insection3,offersomeguidancefor indicativeseparationdistances thatare intendedasastartingpointforStakeholderdiscussions.
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The Guidelines provide guidance in section 4 on a process for determining site specificproximity limits including factors toconsiderwithinriskassessments thatmaybeusedtohelp informproximitydiscussionsandagreements.A checklistof key issues is included inAnnex C. The Guidelines also propose some basic principles to form the foundation ofdiscussionson safe and appropriate solutionson a caseby casebasis, includingpotentialmitigationmeasures.
Oncethepartieshaveagreedsite-specificproximitylimits,thefinalstepintheprocessisthedraftingofaproximityagreementwithaccompanyingmethodstatement.Section5providesguidanceonthistopic.
TheGuidelinesalsocontainguidanceinsection6onhowtodealwithmultiplecablecrossingsin close proximity. Depending upon site specific layout, thismay need specific attention,particularlywiththeincreasingsizeofoffshorewindfarms.
ItisexpectedthattheGuidelineswillprovidetheunderlyingbasisuponwhichallStakeholderscanreachamutuallyacceptableproximityagreement.Intheeventthatproximitydiscussionsfalter,anultimaterecourseintheformofadisputeresolutionprocessisoutlinedinsection11.
3 SCOPEOFTHEGUIDELINEThescopeoftheGuidelineswithrespecttotheproximitydistancesandwaterdepthsthatitshouldbeappliedto,issummarisedinFigure1belowandthefollowingtext.
Proximitydistances
Figure1:ProximitydistancesconsideredintheGuidelines
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TheregulatoryframeworksurroundingthisdocumentisbaseduponcurrentUKpractices.Itis the considerationof theGuidelines thatnoproximityagreement is requiredwhere theminimum approach of planned subsea development and planned/existing subseainfrastructure exceeds one nautical mile (1NM) (1.852 km). However, at a separation ofapproximately1NM,itisconsideredgoodpracticethathigh-levelconsultationisundertakentherebyensuringthatallStakeholdersareawareofeachother’sactivitiesandrequirements.
For a planned subsea development that iswithin 1NM of existing subsea infrastructure,dialogue needs to be established between the Stakeholders and the consideration of theGuidelinesshouldapplytoestablishmutuallyacceptableproximitylimits.
Theindicativeseparationdistanceof750metresgiveninsection3oftheGuidelinesisnotintendedtoprovideaprescriptivesolutiononproximitybutshouldbeusedasasensiblebasecasetobeginStakeholderdiscussionstodetermineactual,casespecificseparationdistances.Multiplecrossingsatlessthan500metresseparationshouldbeconsideredasbeingasingleentitywithassociatedpotentialseabedsterilisation.
Waterdepths
For the purpose of the Guidelines the proximity impacts between renewable energyinstallationsandsubmarinecablesinarangeofwaterdepthsupto75metres,havebeenassessed.Renewableenergydevelopmentsinwaterdepthsinexcessof75metreswillrequirea re-appraisal of the issues assessed here and are therefore beyond the scope of theGuidelines.
4 INTRODUCTIONTheon-goingdevelopmentofoffshorewindfarmshasresultedintheneedforcrossindustryendorsedguidelinesontheproximityofsubmarinecablesandwindfarms.OtherformsofOffshoreRenewableEnergyInstallations(OREI)currentlybeingdeveloped,suchastidalandwave energy, may also be in close proximity to existing seabed infrastructure. Theseguidelines however focus solely on proximity between the various offshore wind farmstructures(OWF)andsubseacables.
There are common interests between offshore wind farm developers/owners and cableownersregardingsafety,accessandmaintenanceandthereisanecessityforthepartiestospatially interact in terms of access to the seabed. The increased use of the seabed forrenewableenergydevelopmentsandthepotentialformultipleusesoftheseabedmustbeappreciated.
TheprimarycommoninterestsofthepartiesaresummarisedinFigure2below:
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Figure2:Primarycommoninterests
The informationsupplied in theGuidelineshasbeencompiledbyacross-sectorTechnicalWorking Group (TWG) comprising members of ESCA (formerly SCUK and UKCPC),RenewableUK (RUK), Renewable Energy Association (REA), The Crown Estate andrepresentatives from telecommunication and offshore renewable energy sector owners,developers,operators,installersandmaintenanceproviders.
TheGuidelines are thereforebasedupon the combinedbroadexperienceandknowledgebasecontainedwithinthesubmarinecableindustry,theoffshorerenewableenergyindustryandTheCrownEstate.
Subject to theDisclaimeron the coverpageof thisdocument, it is the intention that theGuidelinesshouldbeusedasareferencedocumentonthesubjectmatterwiththeaimsofpromotingthehigheststandardsofconstruction,operability,reliability,maintainabilityandsafetyintheoffshorerenewableenergyandsubmarinecableenvironmentcommensuratewithco-existenceincloseproximitytoeachother.
ItisveryimportanttoappreciatethattheGuidelinesdonotprovideaprescriptivesolutiononproximity.Thedistancescontainedwithinthisdocumentareintendedtoprovideastartingpoint for Stakeholder discussions. It is recognised that an OWF developermay generallyprefer to locate structures closer to existing seabed infrastructure than the Guidelinesindicate. Under certain conditions and layouts this may well be possible. Conversely, anexisting seabed infrastructure owner / operator may prefer an increase in the proximitydistancetoanOWFstructure.
Theoptimisedproximitydistancewillonlybeachievedbydialogueandagreementbetweenthepartiesbaseduponariskassessmentprocesswhereappropriate.
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It is in the interest of all Stakeholders that to achieve amutually acceptable andoptimalproximityagreement,veryskilledandexperiencedresourcesshouldbeutilisedduringthesediscussions.ItisoftheutmostimportancethatallStakeholdersunderstandandappreciateeach other’s requirements and safety issues. All parties should therefore commenceproximitydiscussionsasearlyaspossible,proactivelyandwithopenminds.
Evidencebasedstudy
TosupportthedevelopmentoftheproximityguidelineTheCrownEstatecommissionedanevidentiarydesktop(andinterview)studyinSeptember2011(TheCrownEstate,2012).
ThestudyreportcanbefoundonthewebsiteofTheCrownEstatelinkbelow:
www.thecrownestate.co.uk/marine/cables-and-pipelines/studies-and-guidance/
Theevidentiarystudyisnotintendedasaguidelinedocumentinitsownrightbutisprovidedasareferencetoolfortheparties.
5 KEYFACTORSDETERMININGPROXIMITYLIMITS
Submarinecableshavebeensufferingfaultsfromtheoutsetoftheir160+yearhistoryandsotheneedtorestoreasystemquicklyhasalwaysbeenparamount.Stakeholdersinadiscussiononproximitylimitsbetweensubmarinecablesandoffshorewindfarmstructuresareadvisedtodevelopandagreesafeandappropriatesolutionsonacasebycasebasistodeterminehowmuchsearoomisactuallyneededtoefficientlyandsafelyexecuteacablerepair.
Theexperienceacquiredinrepairingsubmarinecableshasevolvedintoarecognisedsetofmaintenance and repair processes and procedures. In order to assist all sectors inunderstandingtheinteractionsandimpacts,fourkeydeterminantsofsearoomrequiredbyacableshipare:
Ø Faultlocation;Ø Cablerecovery;Ø Cablerepair;andØ Re-deployment.
FordetailpleaserefertoAnnexA.
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6 STAKEHOLDERCONSULTATIONIt is vital that all sectors engage with each other at as early a stage as possible in thedevelopmentprocess,regardlessofwhichsectorthedeveloper isfromandwhoownstheexistinginfrastructure.Thisengagementwillfacilitateappropriateproximityagreementsandshouldcontinuethroughouttheconsentingprocessandthroughtheoperationallifetimeoftheassetasillustratedinthebelowprojectcycleoverview,Figure3.
Figure3:Stakeholderconsultationinallphasesoftheprojectlifecycle
ThereissignificantgrowthinOWFsatthepresenttimeandhencemuchdiscussionhereinassumes that the new development is an OWF (and the existing infrastructure being asubmarine cable). It should be accepted that the Guidelines apply equally if the newdevelopmentisasubmarinecableandtheexistinginfrastructureisanOWF.
Stakeholderengagementshouldcommenceassoonasispracticablefollowingtheawardofa development zone or project area and continue with all Stakeholders, throughout theprocess,untiltheprojectisfullycommissioned.
Please refer to Annex B for further details on proposed Stakeholder consultation andinteractionsinUKwaters.
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7 GUIDANCEFORINDICATIVESEPARATIONDISTANCES
TheGuidelinesdonotprovideaprescriptivesolutiononproximity, rather, theystress theneed for proactive dialogue about a site specific, risk based outcome. However, someguidancefor indicativeseparationdistances isoutlinedhere.This is intendedtoprovideastartingpointforStakeholderdiscussions.
Twoprimaryissuestobeobservedwhenconsideringseparationfromthirdpartyvesselsare:
CableMaintenanceVesselSafetyZone–TheSafetyZonearoundthevesselwithrestrictedmanoeuvringability(maintenanceorrepairvessel),fromapproachofothervessels,shallbeestablishedinlinewithCOLREGS1972.Itisalsonormallyrequestedbythevesselmaster(inaccordance with Article V of the Convention for the Protection of Submarine TelegraphCables, 1884), for all ships to keep at least 1NM clear whilst they are engaged in cableoperationsthatrestricttheirabilitytomanoeuvre.
Wind farm Structure Safety Zone –Wind farm operators can request, via the Electricity(OffshoreGeneratingStations)(SafetyZones)(ApplicationProceduresandControlofAccess)Regulations2007(SI/2007/1948),thattypicallya50msafetyzonebeestablishedaroundanywindfarmstructure.GuidancefortheimplementationofsuchsafetyzonesisprovidedbyDECC(DECC,2011).
Twofundamentalconceptsmustbeconsideredwhenderivingagenericproximitydistance:
Ø WorkingZone,appliedeithersideofthesubseacable;andØ HazardArea,appliedaroundthecablerepairvessel.
TheWorkingZoneandHazardAreaconceptsarefurtherdiscussedbelowandcanbefoundillustratedlaterinFigures5,6and7.TheseshowinghowtheWorkingZoneandHazardAreawouldbeappliedtoasubseacablerepairvesselinvariousscenarios.
WorkingZone-AWorkingZoneisrequiredeithersideofanin-servicesubmarinecabletoenable access for cable maintenance and repair operations by a suitable vessel. TheparametersoftheWorkingZoneareafunctionofmanyvariables,severalbeingsite-specific.Nevertheless,theWorkingZoneismostpertinentlythespacerequiredbyavesseltoconductalloperationswhichacablerepairpotentiallycomprises,includingthosediscussedindetailwithinAnnexA.
TheWorkingZonefortraditionalrepairscenariosislikelytobeintheorderof500meithersideoftheexistingsubseacable.Thisisbasedontheexpectedarearequiredtoundertakecablefaultlocationusingtrailedelectrodes,grapnelandfinalbightdeploymentoperations.GreaterdetailcanbefoundinTCEsEvidentiaryStudy.
Guidanceinthisdocumentisconsideredappropriateforwaterdepthsupto75m.
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Considerationshouldalsobegiven,butnotlimitedto,thefollowing:
Ø Proximityofotheradjacentdevelopments(i.e.oilandgas);Ø Proximityofhazards,densityoftrafficandnavigationschemes;Ø Type,sizeandmanoeuvrabilityofvessels;Ø Supportvessels;Ø Cabletypeandexistingburialstatus/protection;Ø Alternative repair options, such as a lay-through repair, or
adjustedfinalbightlocation;Ø Predictedprevailingmetoceanconditions(wind,wave,current,
tides)etc.;andØ Seabedtype.
NothingintheGuidelinesisintendedtodetractfromtheMaster’sresponsibilityforthesafenavigationofthevesselandthesafetyofthoseonboard.TheMasterwillalwaysretaintheprerogativetodepartfromtheGuidelines,oranysubsequentplanoragreementreachedasaresultoftheGuidelines,ifcircumstancesdictate(Ref.AnnexA,Section13.9).
HazardArea-Independentof,andinadditionto,theWorkingZone,wheretherearefixedstructuresneartoavesselundertakingcableoperationsclosetothelimitoftheexpectedorplannedWorkingZone,aHazardAreashouldbeconsideredasatriggerradiusaroundthevessel.IfthereispotentialforaWTGtocomewithinthisHazardAreaasaresultofvesselmovement,thenadditionalriskassessmentneedstobecarriedoutanddeterminationmadeon the need for application of any appropriate pre-planned risk mitigations. Where thissituation occurs, additional consideration needs to be given to supplementary controlprotocols,weatherconsiderations,etc.
The radius of the Hazard Area needs to be determined by discussion between the keystakeholders (e.g.wind farmdeveloper, theexisting subsea infrastructureowner andanyaffectedmaintenanceprovider).TheHazardAreashouldprovidesearoomtoamelioraterisksofworkincloseproximitytoaWTG.Ifthereisnootherdirectionforopeningthatdiscussion,thenitisrecommendedthatconsiderationbeginsataminimumof250metres.Evenatthisminimum distance, there will still be constraints on vessel operations including, but notlimitedto,repairproceduresandweathercriteria.
Figure4showshowtheWorkingZoneandHazardAreawouldbeapplied toasubmarinecable repair vesselwhenoperatingon the cable line, i.e. during jointing,ROVburial/faultlocation,orstockcablelaying.
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Figure4:Vesseloperationonthecableline
Figure5illustrateshowtheHazardAreawouldbeappliedtoasubmarinecablerepairvesselwhenoperatingattheextentoftheWorkingZone.ThisbeingwhendeployingafinalbightbetweentheadjacentWTGsthuspresentingareducedrisksolution.
Figure5:VesseloperationontheextentoftheWorkingZonewhendeployingafinalbight
Figure6illustrateshowtheHazardAreawouldbeappliedtoasubmarinecablerepairvesselwhendrivingawayfromthecablelineduringagrapneldrivetorecoverthecable.Notethat
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theadjacentWTGrepresentsasignificantriskshouldtherebeanylossinvesselposition.Anoptiontoreducetheriskofthisoccurrenceistoplandrivesbetweenturbines.
Figure6:Vesseloperationwhendrivingawayfromthecablelineduringagrapneldriveto
recoverthecable
8 PROCESSFORDETERMININGSITESPECIFICPROXIMITYLIMITS
A generic set of limiting distances cannot be derived for all cable / wind farm proximityscenarioswithoutrecoursetoalargenumberofcaveatsandexceptions.Therecommendedapproachistousetheprinciplesofaholisticriskbasedprocessfordeterminingsitespecificproximity limits. This allows consideration of a range of external influences, both thosebeyondthecontrolofthepartiesandthoseinternalinfluencesthatcanbeaffectedbytheparties.
Oncethepartieshaveagreedsite-specificproximitylimits,thefinalstepintheprocessisthedraftingofaproximityagreementwithaccompanyingmethodstatements.
TheoverallprocessisoutlinedinFigure7below:
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Figure7-Processfordeterminingsite-specificproximitylimitsanddraftingaproximity
agreement
Risk to Personnel and the influence of HSE legislation and regulation is considered to beincludedunderExternalinfluencesinthediagramabove(Figure7),aswellasrisksincludedinOperationalStandardsunderInternalinfluences.
PersonnelriskisproperlygovernedbydetailedlegislationandisthereforeoutsidethescopeoftheGuidelines.However,itshouldbenotedthatSafetyOfLifeAtSeaisoneoftheprimarydrivers foradopting sensibleproximityagreementsand serves tounderpineverydecisionprocessforeitherriskassessmentormitigationselectionandapplication.
RiskAssessment
Inordertocometoasite-specificagreementbetweentheinvolvedpartiesitwillusuallybenecessarytoundertakeariskassessmentduringdiscussionsonproximityagreements.Thisisachievedbyapplyingthecyclicapproachembeddedintheprocess,asillustratedinFigure8andconsideredbelow.
Theriskassessmentshouldincludeananalysisofallrelevantsitespecificinfluences(externaland internal),examplesofwhicharegivenabove. Inorder toprovidea sensiblebasis fordiscussion,risksneedtobeassessedrealistically.
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Fig8-Cyclicapproachtoriskassessment
Safe separation is required between existing submarine cables, WTG and other OWFstructurestoensurethecontinuanceofreasonable,timelyandcosteffectiveavailabilitytomaintain both the existing and the newly installed assets. The requirements of eachstakeholderarehoweverlikelytovarydependingonthesite-specificcircumstances.
InorderfortheinvolvedpartiestoreachagreementitwillbenecessarytodeterminetheAsLowAsReasonablyPracticable("ALARP")risk level that isacceptabletoeachStakeholder.Thiswillbe site-specificand theappetite for risk is likely tovary.Thevarious site-specificissuesshouldbecarefullyanalysedinrespectofriskimpact,andamutuallyacceptableALARPlevelofriskagreed.Considerationoftheacceptableriskswillthenallowinformeddiscussionsonthepotentialmitigationsandleadtosite-specificproximitylimits.
Itshouldbeappreciatedfromtheoutsetbyallpartiesthatnoactivityiseverentirelyfreefromrisk.Companiesandregulatorsdohoweverrequirethatsafetyrisksarereducedtolevelsthat are ALARP. The technique associatedwith this often encompasses the use of a RiskSeverityAnalysistotrytoquantifytheissues.
PleaserefertoAnnexCSection15.3fordetailsofALARPprincipalsandaRiskSeverityAnalysis
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Potentialmitigationmeasurestosupportreachingagreement
Beforedecisionsaremaderegardingproximityandcablecrossings,othersolutionsshouldbeconsidered to potentially mitigate or reduce the impact. Such mitigation measures mayinfluenceaproximityagreement.Examplesofpotentialmitigationmeasuresinclude:
Ø Diverting the existing cable around a wind farm rather thanthroughit;
Ø Provisionofadditionalsparecableforstockandotherwetplantincaseofrepair;
Ø Change the cable repair vessel within the maintenanceagreementandthenecessaryfinancialconsiderations;
Ø Joint use of cable repair vessels in a specific / genericmaintenanceagreement;
Ø ConstructionofawindfarminadifferentareaorreconfiguringtheWTGlayout;
Ø Ifmultiplecrossingsareunavoidable,discussionsoftherequirednumber,locationandspacingshouldtakeplaceandbeagreed;
Ø Undertakeappropriatesurveystoidentifyexactlocationof“inservice”and“outofservice”cablesasrequired;
Ø Agreementonsite-specificmethodologiesforrepair;andØ Methodsofarrestinganylossofvesselposition,e.g.,emergency
anchoringprocedures,supportvessels,etc.
Thislistisnotexhaustiveand,dependinguponcircumstances,additionalmitigationscouldalso be developed by the parties through mutually acceptable operational (and other)proceduresinvolvingwindfarmdeveloper/operator/ownerandtheexistingcableowner/marinerepaircontractoretc.
Thebenefitsof“safehavens”and“escapecorridors”within largewind farmsaspotentialmitigations of riskwere consideredby the TWG. The consensusof discussionswith cablemaintenanceproviderswasthatsuchmeasuresdonotdeliverappreciablemitigation.
PrincipalMitigationconsiderationsforgrossde-confliction
Followingconsiderationoftheissuesofproximityandsafeoperationofco-locatedsubseainfrastructure,itisapparentthatthepresenceofanOWFdevelopmentwillrestrictorpreventdevelopment opportunities for new Subsea Cables through OWFs without both partiescompromising respective systems protection, security and performance objectives. Suchcompromisemaybeeitherunacceptableorundesirable.Optionsformitigationcanthereforebecomeconstrained.
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Someexamplesofpotentialmitigationmeasuresinthisinstanceinclude:
Ø RoutinganewsubseacablethroughanexistingcorridorthroughanOWFbyvirtueofapre-existingsubseacable;
Ø RoutenewsubseacablesaroundOWFdevelopments,betweenprojectsorthroughwindrecoveryareaswheresuitablecorridorsmayexist;and
Ø Subsea cable developers select alternative routes away fromOWFs.
9 PROXIMITYAGREEMENTWhensite-specificproximitylimitshavebeenagreed,abilateralproximityagreementwithaccompanyingmethod statement can thenbedraftedbasedona standard template andtheseguidelines.Suchaproximityagreementshouldbebasedontheformatandspiritofexistingcablecrossingandproximityagreementsincommonusethroughoutbothindustries,whereappropriate.
Itisrecommendedthatwherepossible,finalisationofwindfarmlayoutplanningshouldnotbeundertakenuntilsuchtimeasProximityAgreementsandtherequirementsthereinhavebeen properly reviewed, discussed and agreed at least in principle, with the wind farmdeveloper,thecableownerandanyaffectedmaintenanceproviders.
Survivabilityofagreementsisessentialtotheparties’interests.
Figure9:Thedraftingofasite-specificProximityAgreementandMethodStatement
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9.1 ProximityagreementrecommendationTherecommendedapproach is touse theprincipleofabilateralproximityagreement foreachspecificscenario.
It is recommended that the following key elements are included in such a proximityagreement:
Ø Clausestodefinetheliabilitiesandrightsofbothparties;Ø Theexclusion/inclusionofconsequentiallosses;Ø Detailsof financialcompensationarrangementsforeachparty
whereapplicablerelatingtospecificarrangements;Ø Clearly defined limits of the area to which the Proximity
Agreementapplies;Ø Detailsofhowtheworkwouldbecarriedout,toincludemethod
statements provided by the party carrying out the work andacceptedbytheotherpartyassuitablepriortoworkproceeding,it is recommended that installationproceduresbe included intheAgreement;
Ø Futuremaintenance requirements of both assets. This shouldincludethemethodbywhichnotificationofoperationsbyeachparty is given to the other and the provision and storage ofadditionalplanttosupportagreedrepairmethodologyandtheestablishmentoflocal3rdpartysupportvessels,ifidentifiedasarequirement;
Ø Definitionoftheexpiry/survivaloftheAgreement(forexample,atthedecommissioningand/orrecoveryofoneorotheroftheassets);and
Ø Provisionofrepresentativesfromonepartytotheotherparty'soperations and their rights, obligations and limitation ofauthority.
9.2 SitespecificmethodstatementAmethodstatementisanessentialpartofanyproximityagreement.Thefollowingisataskchecklistwhichthepartiescanuseasabasisfordraftingasite-specificmethodstatement.Itisnot intendedtobeanexhaustive listof itemstobe includedbyprescriptionbutshouldpromptevaluationofthemostusefulandrelevantissuesforconsideration.
Thereneedstobereciprocitywithrespecttomethodstatementsforrepairingandinstallingacrossbothindustries.
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Prerequirementforarepair
Ø Delivery of all as-laid positions of infrastructure – Lat/Longs,geodeticdatum’s,cableburial,WTGdimensionsandbladearc,crossingconstructions,rockplacements,etc.;
Ø Emergency 24/7 contact procedures including escalations,details of any field-specific VHF communication channels anddetailsofsiteengineers;
Ø Historicalmetoceandataoncurrentsandwindtoinformmarineproviders (maynotbeavailable -especiallyduring theO&Mphase);
Ø Establishnotificationrequirementsduringoperations,i.e.,dailyreports,noticeofseabedinteraction,surfacevesselactivity,etc.
Ø Purchaseofadditionalexpendablegear,e.g., additional cable,crossing materials (should preferably be agreed upon duringearlypre-constructiondiscussions);
Ø Establishadditionalmanningrequirements,e.g.,additionalreps,marinewarrantysurveyors,anchorwatchcrews,etc.;and
Ø Establishbridgingdocuments,asappropriate.
Pre-repair
Ø Considerinstallationoflocalpositionreferencesystems;Ø Considertemporarycessationofinterruptibleworksnearby;Ø Establishpreferredsubcontractorsinareaforguardboats,tugs,
othersupportvessels;Ø ConfirmationthatWTG’s,whichareintheareaofthecableship
operations, are stopped and locked in position, preferably ‘Y’position,asnecessary;
Ø Depending on fault nature and location, powering down ofclosestinter-array/collectorcables,asnecessary;
Ø Uptodatemetoceandata;Ø ‘Live’ metocean data feed from any applicable on-site
equipmenttoestablishweatherwindowforrepair(waveriderbuoysonlygiveoutpresentcondition-notforecasts);
Ø Distribution list from all parties for notifications during repairops;
Ø Boardingrequirementsofanyadditionalpersonnel;Ø DPtrialsnearbyrepairsitetoestablishallsystemsfunctioning
correctly;andØ Coordinationmeetingandconfirmationofcommunicationlines
(shoreprojectmanagement).
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Duringrepair
Ø Dailyactivityreporting;Ø Dependentoncommunicationplanwithinproximityagreement,
notificationswhenworksareexpectedtobeseabed intrusive;and
Ø Assistanceinenforcing1NMexclusionzonearoundrepairvesselforothermarinetraffic(asnorequirementasofyetexistforawindfarmtohaveMarineCoordinatorsduringtheO&Mphase,theremaynotbepersonnelashoretomonitormarinetrafficonadailybasis).
Postrepair
Ø Sharingofrevisedinfrastructurelocationdata;andØ Postrepairreviewmeeting/LessonsLearntexercisetofeedback
improvementstotheprocessorrelevantindustrycontacts.
10 MULTIPLECABLECROSSINGSINCLOSEPROXIMITY
A standard protocol for submarine cable crossings is well established and can be founddetailedwithinICPCrecommendations2&3andalsoESCAPolicyNo1.
Multiplecablecrossingsincloseproximityhavebeenundertakenonanumberofoccasionsand are therefore not a new scenario. However, ideally, crossings should be kept to aminimumfromthepointofviewoftheexistingcable(s).
Multiplecrossingswithinawindfarmarea,forexampleatelecommunicationcablecrossinganumberofinter-arraypowercablesasshownonFigure10(forillustrationoftheissueonly)shouldgenerallybeavoidedormitigated.
Theamountandfrequencyofcrossingsshouldformpartofdiscussionsoncrossing/proximityagreementbetweentheparties.
Ifcrossingswerelessthan500mapartitmaymakerecoveryoftheunderlyingcablebetweencrossingsunsafeandimpractical.Assuch,crossingsatlessthan500mseparationshouldbeconsidered as being a single entity and subsequently sterilising that area of seabed andexisting cable. Any repair of the crossed cablewould involve cutting either side of thesecrossingsandlaybackoverthetop.
Itisappreciatedthatthedevelopmentoflargeoffshorewindfarmshascreatedthepotentialforahighconcentrationofcrossingsbymultipleexport,collectorand/orarraycables.Thiscouldresultinlimitingtheavailablespaceforcablerepairvesselstooperateandalsoposetechnicalproblemsregardingcablerecovery/replacementandrepairwithinthecrossingarea.Itisrecommendedthatthefollowingprinciplesareinitiallyconsidered:
Ø Multiplecrossingsofexistingcablesbyexport,collectorand/orarraycablesshouldbeavoidedwhereverpossible;
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Ø Where multiple cable crossings are deemed necessary, thecrossing cables should be spaced so that safe, timely andeconomicalrepairstoboththecrossingandthecrossedcablescanbeconductedwithoutprejudice.
Thepotentialimpactsofmultiplecablecrossingsshouldbecarefullyassessed.Thisshouldbeincludedinthediscussionsofproximity/crossingagreements.Aswithallconstructionwork,there aremany different situations that will need to be consideredwhenmultiple cablecrossings in close proximity are being discussed. Before cables are laid close to or acrossexistingcable(s),itisrecommendedthatthepartiesshouldconsiderthefollowing:
Ø Whentheoperation(s)istobecarriedout;Ø Whichtechnicalmethod(s)willbeused;Ø Whether a pre-lay survey is required along both the existing
cable(s)andtherouteofthenewcables;Ø At what approach distance from the existing cable(s) the
crossing cables can be buried by plough/ROV/othermeans ofjetting;
Ø Ifrequired,whatkindofprotectionshouldbeusedbetweenthecablesatthecrossingpoint(Polyurethane,concrete/bitumenmattresses, rock placement etc.) and the thickness of theseparationlayer;
Ø Intheeventofalaterrepair,whichtechnicalmethodsaretobeused;
Ø HowclosecananROVoragrapnelbeusedtotheotherparty’scable(s);and
Ø Confirmwhohaspriorityinthecaseofsimultaneousfaults.
Figure10:PotentialMultiplecrossingswithinawindfarm(Ref:TheCrownEstate)
11 DISPUTERESOLUTIONPROCESS
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It is recommended that any dispute arising out of or in connection with the parties'negotiations toestablishanagreeddistancebetweenthesubmarinecableandwind farmdevelopmentinquestion(adispute)mayberesolvedbyusingatypicalmediationprocess,anexampleofwhichisshownbelow.
Intheeventofanymatterforexpertdetermination,seniorrepresentativesofthepartiesshall,within[30]calendardaysofserviceofawrittennoticefromanypartytotheotherparties(adisputesnotice),holdameeting(adisputemeeting)inanefforttoresolvethedispute.Ifthepartiesareunabletoagreeuponavenue,thedisputemeetingshallbeheldatanappropriateneutrallocation.Eachpartyshalluseallreasonableendeavourstosendarepresentativewhohasauthoritytosettlethedisputetoattendthedisputemeeting.
Iftherepresentativesofthepartiescannotresolvethedisputewithin[60]calendardaysaftertheserviceofadisputesnotice,whetherornotadisputemeetinghasbeenheld,thedisputemust be referred to a senior manager of UK operations of each party who must use allreasonableendeavourstoresolvethedisputewithin[30]businessdaysafterthedispute isreferredtothem(referralperiod).
Anydisputewhichisnotresolvedwithinthereferralperiod,shall,attherequestofanypartymade within [30] calendar days of the expiry of the referral period, be referred to anindependentexpertfordetermination.
Thepartiesshallagreeontheappointmentoftheexpertandshallagreewiththeexpertthetermsoftheirappointment.Ifthepartiesareunabletoagreeontheidentityoftheexpert,orifthepersonproposedisunableorunwillingtoact,then,within[30]calendardaysofeitherpartyservingdetailsofasuggestedexpertontheotherortheproposedexpertdecliningtoact, either party shall then be entitled to request that an expert be appointed by anindependentarbiter.Allcostsofandassociatedwiththerequestfortheappointmentofanexpert by the independent arbiter shall be borne equally between the parties. The expertappointed may be an individual, partnership, association or body corporate and shall begenerally recognised as an expert in the field of cable installation andmaintenance. Theindependentarbitershallbemutuallyagreedbetweentheparties.
Theexpertshallactonthefollowingbasis:
a. on their appointment, the expert shall confirm his neutrality,independence and the absence of conflicts in determining thedispute;
b. theexpertshallactasanexpertandnotasanarbitrator;c. the expert's determination shall (in the absence of manifest
error) be final and binding on the parties and not subject toappeal;
d. the expert shall decide the procedure to be followed in thedetermination in accordance with this agreement and inconsultationwiththepartiesandshallberequestedtomakehisdeterminationinwriting,withreasons,within[30]calendardaysaftertheirappointment.
e. Fortheavoidanceofdoubt,allcostsrelatedtotheinstructiontheexpertshallbeborneequallybytheparties.
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12 RECOMMENDEDCONSIDERATIONS,GUIDELINESANDREFERENCES
WhenplanningtherouteofsubmarinecablesitisrecommendedthatdevelopersconsultthefollowingInternationalCableProtectionCommittee(ICPC)andESCAguidelines/policies:
ICPC–www.iscpc.org
Ø RecommendationNo.1:“ManagementofRedundantandOutofServiceCables”
Ø RecommendationNo.2:“RecommendedRoutingandReportingCriteriaforCablesinProximitytoOthers”.
Ø Recommendation No.3: “Criteria to be applied to ProposedCrossingsbetweenSubmarineTelecommunicationsCablesandPipelines/PowerCables
Ø Recommendation No.4: “Recommended co-ordinationproceduresforrepairoperationsnearinservicecablesystems”
Ø Recommendation No.7: “Procedure to Be Followed WhilstOffshoreCivilEngineeringWorkIsUndertakenInTheVicinityOfActiveSubmarineCableSystems”
ESCA–www.escaeu.org
Ø PolicyNo.1:“CableCrossingAgreements”
DECC,2011.NationalPolicyStatementforRenewableEnergyInfrastructure(EN-3).[Online].Availableat:
http://www.official-documents.gov.uk/document/other/9780108510793/9780108510793.pdf
Electricity(OffshoreGeneratingStations)(SafetyZones)(ApplicationProceduresandControlofAccess)Regulations2007(SI/2007/1948),.Availableat:
http://www.legislation.gov.uk/uksi/2007/1948/contents/made
TheCrownEstate,2012. Submarinecablesandoffshore renewableenergy installations–ProximityStudy:
www.thecrownestate.co.uk/marine/cables-and-pipelines/studies-and-guidance/
13 ANNEXA-KEYFACTORSDETERMININGPROXIMITYLIMITS
The experience acquired in repairing submarine cables has evolved a recognised set ofmaintenance and repair processes and procedures. In order to assist all sectors in
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understandingtheinteractionsandimpacts,thefourkeydeterminantsofsearoomrequiredbyacableshiparesummarisedinthisAnnex,namely:
Ø Faultlocation;Ø Cablerecovery;Ø Cablerepair;andØ Repairbightdeployment.
Inaddition, the followingbasicoperating issuesgoverning thedeterminationofproximitylimitsareaddressed:
Ø Vesseldesignandcapability;Ø Anchoredoperations;Ø Operations within a Hazard Area (or Area of Enhanced
OperationalAwareness);Ø Safetymanagementandcompetency;andØ TheroleoftheMaster.
Part of the information contained in thisAnnex is extracted fromTCE’s Evidentiary Studywhichcontainsmorein-depthinformationaboutthesubjects,includingoverviewtablesandworkedexamples.Itisgenerallyrecommendedtoconsultthisstudyreportwhenconsideringspecificissuestobeanalysedforinclusioninaproximityagreement.
13.1 FaultlocationConfirmationof fault locationandcable recovery is carriedoutbyROVswheremetoceanconditionsallow.Theuseofelectrodes,trailedbehindtherepairshipasitzigzagsitswayalongthecableroutemayhoweverbenecessaryforfaultlocationundercertainconditions.
Trailed electrodes remain awell proven technique for fault finding in both telecoms andpowercablerepairoperations.Forexpediencyitiscommonforthemainrepairvesseltocarryout the work but auxiliary vessels may also be employed if these are available and theoperationalconditionsaresuitable.
Ineithercase,thesea-roomrequiredforthevesseltosafelyandefficientlymanoeuvrewhilstusingtrailedelectrodesmustbeproperlyconsideredwithintheproximityagreement.
AtypicalmanoeuvringpatternisillustratedinFigure11below.
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Figure11:Theprocessofdeterminingfaultlocationthroughtheuseoftrailedelectrodes.
(InternalDocument,GMSL,2011)
Electrodeswouldbeapproximately150minlengthin50mDOW,andtypicaldistanceofflinewouldbe400-500m.Thelatterdistance isafunctionofelectrodelength,ship lengthandrequirementtotowtheelectrodesfarenoughawayfromthecablelinesothatanydeflectionissufficientlypositivetoinformajudgementonfaultlocationandnotbeovertlyaffectedbybackgroundnoise.
13.2 CablerecoveryThe recovery of telecommunication cables for repairmaybe undertakenby conventionalgrapplingtechniques, theuseofROVoracombinationofboth.Thesea-roomrequiredtoefficientlyexecutecablerecoveryisoneofthekeydeterminantsofcableandOWFproximity.Thisshouldbeproperlyaddressedinthedrawingupofproximityagreementsandassociateddocumentation.
ROVs&RelatedSubseaEquipment
Inmostcases,ROVinterventionwouldbethepreferredcableinterventionmethodinwaterdepthsupto200m,atleastinitiallywhenthefaultlocationwouldbeinspected.OnceinitialROV inspection has been completed then the options become broader ranging, includingtowedgrapnels.The recoverymethodwouldbedictatedbyseabed type,depthofburial,environmental parameters, cableofflinedistance (inwhich caseROV is preferable), cabletype,proximityofhazards,etc.
Ifthesefactorsallow,oncethefaulthasbeenlocatedthecablewillbeexposed,cutbytheROVand recoveredbya lift line, thus reducing theamountof systemcable removedandminimisingcableshipexcursionsfromthecableroute.Alternatively,theinitialcutmaybeperformedbyROVbeforethetwocableendsarerecoveredtodeckviagrapnels. Insomesituations,useofROVmayberestrictedtoinitialfaultlocationandidentificationofsuitablelocationstoconductrecoveryviagrapnelsonly.
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IndicativebasecaseproximitylimitsforROVs,andothersubseatoolscanbefoundinTCE’sEvidentiaryStudy.
GrapnelOperations
Grapplingremainsavaluablecablerecoverytechnique,especiallywhenmetoceanconditionsorcableburialprecludetheuseofROV.Thisactivitywillusuallyconsistofacuttingdriveatthe fault position followedbyholdingdrives to recover the two cableends.De-trenchinggrapnelunder-runningispotentiallyrequiredwhentherecoveryofcablesfromdeepburialwouldotherwisecreateexcessivetensionsonthecableduringrecovery.
Thedistancerequiredtoconductbothcuttingandholdinggrapneldrivesisbroadlysimilarandisafunctionofshiplength,grapnelriglengthandrun-on–aDOWdependentdistancedeemedappropriatetoensurethegrapnelshavesufficientopportunitytoengagethecable.Grapnel runs would preferably be conducted up any substantial seabed gradients andperpendicular to the cable route, hence they result in the cable ship making significantexcursionsfromthecablerouteasinFigure12below.
Figure12:Exampleofindicativedistancesrequiredwhenconductingtraditionalcable
recoverymethodswithgrapnelsin50mdepthofwater
Thesizeofexcursionshown inFigure12fromthecableroutemaybereducedbyusingashortenedgrapnelriglayback,conductingoperationswiththevesseldirectionparalleltothecablelineorbymakingoptimaluseofconditions(furtherdetailsrelatingtosuchascenarioareprovidedbyTheCrownEstate(2012)(refertoTable0-4ofthatStudy)).However,thenormal scenario above should be allowed for when discussing proximity and, as grapneloperationsrequiremoresea-roomthanROVcablerecoverymethods,theuseofgrapnelsisakeyconsiderationforthisguideline.
Table1isofferedasaguidelinesetofbasecaseoperationaldistancesforgrapneloperations.It is acknowledged however that final proximity limits for a given repair scenariowill be
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dependent on a large number of variables that combine to produce a unique set ofrequirementsforeachcablerepair.
Table1-Indicativereducedgrapneloperationdistances(TheCrownEstate,2012)
Thereduced laybackandrunondistancesprovidedbyTheCrownEstate(2012)aretobeconsideredas‘shortened’distancesandarederivedassumingthemostoptimumconditionsand a reduced grapnel layback. In practice, an allowance for differences in grappling rigarrangements, operational contingency (e.g. wind & tidal effects) and attention to theparticular circumstances of the case should bemade and the arguments expressed hereadjustedaccordingly.
13.3 CablerepairOnceacableendhasbeenrecoveredand“recovery”damageremoved,thesystemistestedtodeterminewhethertheendisfaultyorfaultfree.Iffaultythevesselwillproceedtoclearthefaultiflocaltotherepairvessel.Oncethecablehasbeencutbacksufficientlytoremovethe fault and has been tested successfully the cable shipwill buoy off the good end andrelocatetorecovertheothersideofthecable.
Thecableshipwillrepeattheprocessonthesecondenduntilitisstandingtoafaultfreeendandwill then splice toa lengthof repair “stock” cable.Once this splice is completedandtested,thecableshippaysoutthenew“stock”cablesection(dependinguponthepositionofthecableendsduringfaultlocation,thecableshipwillaimtoplacethecableontheoriginalcableline)layingouttothefirstcableendbuoy–includinganycrossingconstructionswhichmayberequiredoverinter-arrayorexportcables.
Whenthecableshipreachesthecablebuoyitwillrecoverthefirstend,testbothendsandperformthefinalsplice(seeFigure13below).
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Figure13:Therepairofacableisusuallynotdimensionedinrespectofproximitydistance
toawindfarmstructure
13.4 RepairbightdeploymentOncethefinalrepairjointiscompletethevesselwillmanoeuvretolaythefinalbight,asinFigure14over,and,ifpossible,theentirerepairfootprintwillbere-buriedusingtheROV.
It shouldbenoted that thephysical characteristicsof the repairbightaredictatedby thevariationsindesignandpurposeofthevesselinvolved.
Figure14:Exampleofindicativedistancesdisplacedoffthecablelinewhendeployinga
finalbighttotheseabedin50mdepthofwater
Thedisplacementofafinalbightcreatedbyacablerepairwillbeafunctionof:
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Ø waterdepth;Ø thephysicalcharacteristicsofthecable,particularlybendradius
andcatenary;Ø deck length, jointing space layout and freeboard of the cable
repairvessel;andØ prevailing weather conditions at the time of the laydown
operation.
Figure 15 illustrates the terms ‘water depth’, ‘freeboard’, ‘deck length’ and ‘repair bightcrown’.
Figure15:Termsrelatingtocablerepairbights
ThedeploymentofafinalbightislikelytobethekeydeterminantofthespacerequiredtoconductmaintenanceofasubmarinecableinthevicinityofanOWFdevelopment.Notonlyis it likelythattheoperationduringarepairrequiresthegreatestexcursionoffline,henceplacingthevesselclosertotheOWFthanatanyotherstageoftherepairoperation,ittakesplace when the cable ship is least manoeuvrable and most constrained in her ability torespondtoanylossofposition.Amethodtoreducetheriskoftheproximityoftheshipandthenearestwindturbinesistoplanthedeploymentofthefinalbightbetweenorawayfromtheturbines.Ifpracticable,theROVwillalsobeutilisedtoinspectandre-burythecablepostrepair. Attention is drawn to the differences in bight deployment techniques betweentelecomsandpowercables.Also,thedifferencesinpreparationandlayingoutofcableendsfor jointing are significant when comparing telecoms and power systems. As such, duerecognitionofeachshouldbefullyincorporatedinallproximityplanning.
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13.5 VesseldesignandcapabilityItisdemonstrablethatwithincreasingtechnicalreliabilityofpropulsionandcontrolsystems,themaincausesofDPstationkeeping incidentsarerelatedtohumanerror.WhiletheDPclassofaparticularvesselremainsrelevant,proceduralregimesandbehaviouralsafetyareconsideredtobeofsignificant importance indevelopingproximity limits forDPandotherself-propelledvessels.
DPClass1vesselsincommonusewithinthetelecommunicationscablerepairsector,providelowerlevelsofredundancyintheeventofasystemfailureorlossofposition.Providingproperoperatingcontrolsandproceduresarefollowed,however,theuseofDPClass1vesselsshouldnottranslateintomorestation-keepingincidentsthanforDPClass2vessels,providingsuchDPClass1vesselsareoperatedmoreconservativelyintermsofproximitydistances.
13.6 AnchoredoperationsAnanchoredbargemaybeusedforcableinstallationorrepairsinproximitytoawindfarmorconverselyforwindfarmworkinproximitytoanexistingcable.Theuseofjackupbargesfor wind farm construction or cable repair activities can also involve the deployment ofanchorstoaidpositioningpriortojackingoperations.
While the deployment of anchors represents an additional constraint when planningproximitylimits,thefactthatanchorlinescanspananexistingsubseacableallowsadegreeofflexibilityintheuseofanchorsinacongestedseabedarea.
Whileitisnotpossibletoprescribeminimumproximitylimitsforanchorsandwiresthatsuitallsituations,givenpropercontrols,somebasecaselimitsforanchoredoperationscanbefoundinTCE’sEvidentiaryStudy.
Theproximityanddirectionofanchorsshouldbegivenspecificconsiderationandproceduralprocessinthesiteproximityagreement.
13.7 SafetymanagementandcompetencyThe station keeping performance capability of any vessel is a combination of design,maintenancestandardsandoperationalcompetenceinthefaceofenvironmentalandsitespecificconditions.Thisguidelineconsidersthatcloseattentiontosafeoperatingpractices,competency assurance and behavioural based safety should be equally important as thetechnical reliability and performance of vessels and equipment when defining proximitylimits.
Whilstthesafeoperationofvesselsislegislatedatinternationalandnationallevels,therearearangeofapplicablesafetystandardsdependingonthesizeand/orpowerofaparticularvessel.Somevessels(particularlytowedbarges)falloutsidethemorestringentrequirementssuch as the International Safety Management (ISM) Code. It is recommended that the
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principlesoftheISMCodebeappliedtoproximatevesseloperationsirrespectiveofvesselsize,powerorclass.
13.8 OperationswithinaNotificationAreaTypical crossing and proximity agreements generally prescribe additional safety controlswithinadefinedareaaroundafixedorfloatingstructureinordertomanagetheadditionalsafetyhazardspresent.A‘NotificationArea’aroundstructuresisoftenadoptedwherevesselentrywould activate these additional requirements specified in the crossing or proximityagreement. It is recommended that thedefinitionof such a notification areabe includedwithintheproximityagreementwithinwhichaheightenedlevelofoperationalreadinessandsafetyawarenessbeactivated.
13.9 TheroleoftheMasterIncommonwithconventionalmaritimelawandpractice,theship’sMasterhasoveralllegalresponsibilityforthesafetyofhisvessel,thepersonnelon-board,andtheprotectionoftheenvironment.Itisrecommendedthatthisisproperlyacknowledgedinthedevelopmentandspiritoftheproximityguidelinesandthatnothingcontainedthereinshoulddetractfromthisultimateresponsibilityforthesafeconductofoperations.
Itshouldbenoted,theprerogativeofthevessel’sMasterwillplayasignificantpartintheactual executionof theworks that aredefinedwithinanyproximity agreementand in allvesseloperationsdiscussedtherein.Thisguidelineconsidersitimperativethatmaintenancesuppliers and theirmarine personnel (of both parties) be engaged in both the proximityagreementformulationandanyrepairoperationplanning.
14 ANNEXBSTAKEHOLDERCONSULTATIONThisAnnexdescribesatypicaloffshorewinddevelopmentprogrammeandthesequenceofhighlevelactivitiesandproposedstakeholderinteractionsduringthevariousprojectphases.The TWGacknowledges that someOWFdevelopersmay choose to progress furtherwithproximityagreements,priortoconsentapplication,thansuggestedbelow.However,Figure16below, and theexplanatory text, provides someguidanceon the suggested timingsofinteractionsbetweenanOWFdeveloperandsubseacableoperator.
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Figure16:Suggestedstakeholderconsultationduringdevelopmentandconstructionofan
offshorewindfarmproject
14.1 DevelopmentandconsentingphaseThe UK processing model for offshore wind farms can take more than 5 years fromidentificationofadevelopmentzonethroughtocommencingconstruction.Developershaveanumberofstagestocompletebeforegainingplanningconsent.Owingtothenatureoftheplanningsystemforoffshorerenewableenergyprojects,detailedandeffectiveengagementis required with all stakeholders during this time and the developermust report on thisconsultationandontheway inwhichstakeholderconcernshavebeentaken intoaccountwithin their consent application. To assist in this process, The Crown Estate maintains a‘phonebook’listingallappropriatecontacts.
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The first liaison activities between the developer and the involved stakeholders shouldincludeadviceonintent,processandtimescalesofthedevelopment.
Communication should include the issue of charts providing details of the site underdevelopment.Wherepossible, this couldalsobeprovided ina suitableGIS format. Oncecommunicationshavestarted,follow-upcommunicationshouldcontinueonaregularbasis–perhapstwiceayear(althoughthisshouldbeagreedonacase-by-casebasis,dependingonthepotentialnatureoftheinteractionbetweenparties).
Onceaproject(orzonedevelopmentplan)isbetterdefined,one-to-onemeetingswiththeaffectedstakeholdersshouldcommence.Thekeyaimofthesemeetingsshouldbetodiscussproximityissuesandthepotentialrequirementsforcablecrossings.UnderthePlanningActa developer must demonstrate a suitable level of consultation and engagement with aproject’sstakeholders.Asaresultitwouldalsobebeneficialtodiscusstheoverallnatureoftheprincipleswhichwillneedtobeestablishedbetweenthetwopartieswhencomingtoproximityorcrossingagreements.
Itshouldbenotedthatevenatthepointofconsentapplication,thewindfarmdevelopermaynotknowtheexactlayoutoftheoffshorewindfarm.Windfarmsareusuallyconsentedona‘projectenvelope’basis,knownasaRochdaleEnvelope,whichallowsforavarietyofpotentialoptions in technology, layouts, project size, etc., to be built out. Importantly for thisdocument,thelayoutsareonlylikelytobeconfirmedpost-consent.Whilstsomedeveloperswillbehappytosignuptocertaindistancesonwhichaproximityagreementcanbereachedbeforeconsent,itmaynotbepossibletosignfullproximityandcrossingagreementsbeforethesubmissionofaconsentapplicationifdeveloperscannotprovidethislevelofcertainty.Itisthereforeanticipatedthatwheredeveloperscannotsignuptocertainconstraintsbeforeconsentapplicationandhencewheretherearepotentialconflictsbetweenacableandanoffshorewindfarmproposal (andwherethere isapossibilitythatthecableoperatormayobjecttotheIPC/MarineScotlandasaresultoftheconflict)theaffectedpartiesmaylooktodevelopatwo-stageagreement.Thesuggestedstagesforthisaredetailedbelowbutmayneedtobeadaptedtomeettheneedsofindividualdevelopersandtheirstakeholders.
Whilstanoffshorewindfarmdeveloper,inthisinstance,wouldnotbeabletoprovidefinaldetailsofaprojectlayoutpreapplication,itissuggestedthatpartiesconsiderenteringahighlevel Memorandum of Understanding (MOU) before a developer submits a consentapplicationtoavoidtheneedforanyobjectiontoanapplication.The levelof informationwithinthisMOUwouldbelargelydependentonthedesiredlevelofagreement,pre-consent,oftheOWFdeveloperandcableowner.ItissuggestedthatsuchahighlevelMOUwouldlooktoestablishtheprinciplesonwhichaproximityagreementwouldbereachedfortheprojectinquestionandwouldintendtofocusthepartiesontheprincipleslaidoutwithinit.
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SuchahighlevelMOUmaylooktoidentifyminimumproximitywithoutanycompromisetomaintenanceoperationsonthetelecomsoperator’spartaswellas,forexample,suggestingsuitablemitigationmeasuresthatcouldbeadoptedshouldproximitybereducedinanumberof increments. This may present numerous scenarios on which the offshore wind farmdevelopercouldbaseadesignwhenfinalisingthewindfarmdesigndependingonthefinalprojectparameters,henceretainingtheflexibilitycontainedwithintheRochdaleEnvelope.
ItisrecognisedhoweverthatanMOUmaynotbeapplicableorappropriateforalldevelopersandhenceitissuggestedhereasoneoptiontoeaseconcernsofbothparties.Adeveloper(orexistingcableowner)mayprefertotakeanotherapproachaspartofongoingconsultationontheproximityagreement.
During the discussions on a high levelMOU, the partiesmay agree to undertake certainimpactassessmentanalysesandtechnicalstudies,ifrequired,todeterminethelevelofriskimposedandallowaninformeddiscussionofpotentialmitigations.
Ifconsideredappropriate,ahighlevelMOUwouldbeputinplacebetweenthedeveloperandtheaffectedpartyaspartoftheconsultationprocess.Inthiscase,itwouldprovidetheoffshorewind farmdeveloper and affectedpartywith the reassurance that a projectwillproceedonthepreviouslyagreedtermsandhencewillavoidpotentialfurtherdisputeatalaterstage.
Inthisscenario,thesecondstageoftheproximityagreementwouldoccurpost-consentandoncethelayouthasbeenapproved,wheredetailedagreementsbetweencableoperatorsandoffshorewinddevelopersarefinalisedandagreed(asdiscussedfurtherinAnnexB.3).
14.2 Pre-constructionphase
Onceconsentisgrantedbytherelevantauthority,thedeveloperwillstartnarrowingdowndesign options for the offshore wind farm through detailed design, tendering andprocurementprocesses(althoughsomedevelopersmaybeginthisprocessduringapplicationdetermination).Duringthisperiodoftime(typicallyapproximately2years),thedevelopershould continue toengagewith the cableownersandestablishmore firmproximity (andcrossing)agreements in linewith thepreviouslyagreedprinciples laidoutwithin thehighlevelMOUoranyotherapplicabledocuments.Thesewouldbebasedontheestablishedwindfarmlayout,electricalinfrastructure,etc.
Dependingonthenatureoftheoffshorewindfarmconsent,theremayalsobearequirementtodemonstratetotheregulatorthataproximityagreementhasbeenreached.
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14.3 Constructionphase
Once the financial investment decision is taken by the developer’s board(s) and offshoreconstruction is mobilised, there will be certain precautions to be taken in respect ofconstruction operations near offshore cables. This is detailed in the method statementforminganintegralpartofanyproximityagreement.
Representatives of installation and/or maintenance contractors should be involved inoperational discussions as early as possible, as necessary. This is to enable agreement ofworkingarrangementsforinstallation,repairandmaintenanceoftheparties’facilitieswithintheboundsoftheproximity(andcrossing)agreement.
Notificationfordefinedactivitiesshouldbeprovidedasagreedonacasebycasebasis.Anexampleofanotificationtimelinecouldbeatcountdownintervalsof3months,1month,1week, 48 hours, 24 hours prior to construction commencement and upon completion ofoperations. Any alterations to the Method Of Procedure (MOP) during construction willrequirefurtherdiscussionandflexibilityintheproximityagreement.
14.4 OperationandmaintenancephaseFollowingconstruction,thecoordinatesandnecessarychartinginformationshallbesuppliedtoallpartiesassoonaspracticaltoenablethemtoupdatetheirdatabases.Theobligationistoprovideas-builtdataworksforallparties.Thewindfarmoperatorshouldprovideas-builtdataandas-laidcoordinatesofallinfrastructure.Submarinecableoperatorsshouldprovidearevisedroutepositionlistafteracablehasbeenliftedforrepairor installationofanewcable.
Duringtheoperationandmaintenancephasetherewillbenewissuesinrespectofmarinecoordination, issues duringmajor overhauls, etc., and theremight be options for sharedmaintenanceservices.
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15 ANNEXC–CHECKLISTFORISSUESTOBECONSIDEREDINASITESPECIFICRISKASSESSMENT
This Annex provides a check list of the key issues (‘External / Internal Influences’) forconsiderationinasitespecificriskassessment. Itmaybeappropriatetoconsidertheseaspartofasuggestedagendafordiscussionbetweenthekeystakeholders.
Figure17–TheExternalandInternalInfluencestobeconsideredindeterminingsite
specificproximitylimits
15.1 ExternalinfluencesThefollowingisanaide-memoireofthekeyareasof‘ExternalInfluences’(i.e.issueswherenone of the affected parties can have an impact on the condition) for consideration inreachingsuccessfulproximityagreements.Itisnotintendedtobeanexhaustivelistofitemstobeincludedbyprescription.
Physicalenvironment/metoceanconditions
Ø Historicalmetoceandata;Ø Benthicconditions;Ø Depthofwater.
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Existinginfrastructure
Ø Availabilityofaccuratesurveydata;Ø Existing subsea plant information (burial / protection) and
specification;Ø Other seabed users / stakeholders and proximate
developments;Ø Cablecrossingsandanyrequiredburial/protection(mattresses,
rocketc.);Ø Proximityofsurroundinginfrastructurefoundations/turbines/
substations.
Plannedinfrastructure
Ø Planned location and potential layout scenarios, includingcrossings.
Legislative/regulatoryconstraints
Ø UNCLOSandotherregulatoryconstraints;Ø HSEregulations;Ø Localrulesandregulations;Ø Other permit applications lodged during development of a
proximityagreement.
Commercialconstraints
Ø IsahighlevelMOUbetweenthepartiesinplace?;Ø Impact on contractual performance requirements of cable
owner’scustomers/marineprovider;Ø ReductioninOWFdeveloper’spowergeneration.
Otherseabedusers
Whensubmarinecablesarelocatedincloseproximitytooffshorewindfarmdevelopmentsandotherstakeholders(suchasoil&gas,shipping,aggregateextraction,marineprotectedareas, etc.), the developer should consider the cumulative impact of all the sectors’requirements.Thisshouldensureeachstakeholdercancontinuetheirlegitimateactivitiesina safe and timely manner. Where impacts are identified, they should be quantified andassessed, and all legitimate concerns addressed. Where multiple developments /stakeholders are identified, the Working Zone agreed between stakeholders using thisguidelinemayvaryonacasebycasebasis.
15.2 InternalinfluencesIn addition to the External Influencesoutlined above, a rangeof ‘Internal Influences’ (i.e.issuesthatareinsomekindofcontrolbyatleastoneoftheaffectedparties)shouldalsobetakenintoconsiderationwhendiscussingarisk-basedassessmentofappropriateproximitylimits. Again, the list is not intended tobe exhaustiveor prescriptivebut shouldpromptevaluationofthemostusefulandrelevantissuesforconsideration.
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Also,theseinternalinfluencesshouldbepartoftheagendafordiscussionbetweenthekeystakeholdersandmayeventuallybeelementsofthemethodstatementstobedevelopedandagreedthroughthedialogue.
Vessel/Equipmentselectionoravailability
Ø Differingvesseltypes,capabilitiesandoperatingfootprints;Ø Vesselandpositioningcapability;Ø Weatherforecastandrelateddecisionprocess;Ø Impactofvessellosingposition;Ø Vessels required to undertake remedial works – multi-vessel
simultaneousoperations;Ø Position reference systems and the impact of surrounding
structures;Ø Deckandcablehandlingarrangements;Ø ROV/LARSspecandcapability;Ø Methodology, operational procedures and techniques
employed;Ø Availablesparecable/plant.
Operationalenvironment
Ø Proximityagreementboundary;Ø Pre-existingjackupzonesandcable-freeareas;Ø Anchorspreadrequirementsformulti-pointmooringsystems;Ø Cableprotection;Ø Post-laysurveysandthetransmitting/sharingofdata;Ø Howarepairaffectsfutureinteractionandworks;Ø The requirement for powering down part of a system during
works.
Manninglevels
Ø Competence and experience adequate tomeet the additionaldemandsofthecircumstance;
Ø Additional manning requirements, e.g. DPOs, watch keepers,proximate party reps, operational personnel to expedite therepair,etc.
Personnelcompetency
Ø Ensurethatrelevantcrosssectorexpertiseisengaged;Ø Health,SafetyandEnvironmentalconsiderations;Ø Experience in proximate / close quarters / simultaneous
operations.
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15.3 ApplicationofALARPWhatisALARP?
TheALARP level should not bemisunderstood as simply being a quantitativemeasure ofbenefit against detriment. ALARP is reached when the time, trouble and cost of furtherreductionmeasures,becomeuneconomicorunacceptablewithrespecttotheadditionalriskreductionobtained.
In order to come to an agreement between the involved parties it will be necessary todeterminethelevelofriskALARPlevelwhichisacceptabletoeachstakeholder.Thiswillbesitespecificandtheappetiteforriskislikelytovary.
Whilstaccountshouldbegiventopotentialworstcasescenarios,theseshouldnotbeusedas the basis for discussions between the parties if they cannot also be considered likely.Limitingdiscussionstoworstcasescenariosor,forinstance,asingle20year+event,islikelytoleadtodisagreementswhereneitherpartycanbesatisfiedormaypotentiallypreventanagreementbeingreachedatall.Whereverpossible,theassessmentofriskshould include,butnotbelimitedto:
Ø Any historic data available on reliability or damage for theexistinginfrastructureorinstalledsimilarexampleselsewhere;
Ø Likelyreturnratesofperiodsofpoorweatherwhichmay,undertheplannedinteraction,prejudicerepairswhencomparedtothebaselinecurrentsituation;
Ø Likelihoodofinabilitytomaintaincontrolofthevessel;andØ Completionofsufficientduediligencetoensurethatallparties
to the agreement are considered competent to meet therequirementsoftheproximityagreement.
Considerationoftheacceptableriskswillthenallowinformeddiscussionsonthepotentialmitigations that may be available to reduce the risk caused by a new development andthereforereachanacceptableALARPlevel.
ConsiderthefollowingProbability–ImpacttableandRiskSeverityAnalysisexamplewhendeterminingandmitigatingtotheALARP(YELLOW)level(s).Note,theriskseverityindexcanbecalculatedsimplyasProbabilityxHighestImpact,thesolutionbeinginsertedwithintheP-ItableintheGreen(Tolerable),Yellow(ALARP)orRed(Intolerable)areas.
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Thismightbeviewed inaProbability / Impact (P-I) severity tableasoutlined inFigure18below.
HighestImpactofRiskEvent
Figure18:ProbabilityImpacttableandassociatedALARPlevels
A risk analysis taking into consideration all site-specific External Influences and InternalInfluencesshouldbecarriedoutduringdiscussionsonproximityagreements.ThebasecaseproximitydistancetablesprovidedintheEvidentiaryStudyappliedintelligentlyprovideusefultoolsintheriskassessmentofthevariousscenarios.
Suchanassessmentcouldincludebutnotbelimitedto:
Ø Risk/likelihoodofdamagetoexisting/proposedinfrastructureinthe area of the interaction including potential for change toanticipatedfaultratesduetotheplannednewinfrastructure;
Ø Risk/likelihood that a faultmayoccurduring aperiodofpoorweatherwhichwouldleadtheMasterofthevesseltodelayorsuspendoperationsdueto theproximityofanOWFalone (asopposedtotheweatherbeingunworkableinanysituation);
Ø Acceptable level of downtime of any infrastructure undernormalcircumstancesanditsstrategicimportance;
Ø LossofpotentialrevenueforanyOWFoperatorasaresultoflossofavailableacreageandimpactontheprojectasawhole;
Ø Cost of alternative options, such as, re-routeing a new cablearoundasopposedtothroughanexistingOWFandimpactontheprojectasawhole.