SYDNEYTRAINSELECTRICALNETWORKUPGRADEOIL/GAS|SEWER|STORMWATER|POWER|WATER|TELCO

LOCATION Erskineville,Haberfield&LeichardtNSW

CLIENT SydneyTrains

PIPE 180mmHDPEorangeelectricalconduits

GEOLOGY Rock,clay&fillgroundconditions

LENGTH 264metres

TECHNIQUE HDD

PROJECTOVERVIEWUEA’sHDDdivisionhasrecentlycompletedtheunderboresrequiredaspartoftheSydneyTrain’sElectricalNetworkUpgrades inHaberfield,Leichardt&Erskineville.Aspartof theproject,usingVermeerD6090&DitchWitchAT3020HDDrigs,UEAcompletedthreeseparateunderboresat:

o BartonAve,Haberfield–84metres:4xDN180HDPEelectricalconduitswith50mmspacerso DarleyRoad,Leichardt–130metres:4xDN180HDPEelectricalconduitswith50mmspacerso EveleighYard,Erskineville–50metres:3xDN180HDPEelectricalconduitswith50mmspacers

SCOPEOFWORKSHaberfield&LeichardtSydney Trains 11kV feeders 533A and 533B previously provided connection between Lewisham andStrathfieldsubstations.ThesefeederscrossHawthorneParadeCanalinHaberfieldoverafootbridge,whichwasnolongersafeforpedestrianuseandhasbeenreplacedbyanalternativebridge,approximately130metresnorthoftheexistingbridge.Theobjectivewastorelocatethe11kVfeeders(533Aand533B)fromtheretiredfootbridgetothenewTransportforNSW(TfNSW)footbridge,whichwasconstructedwithfourspareconduitssuitableforaccommodatingthefeedersinanticipationofthisproject.UEA’sscopeofworksincludedtheconstructionoftwounderboresrequiredforthisproject(seeabovephoto):anunderboreatBartonAvenue,andanunderboreatDarleyRoadundertheLightRailcorridor.Erskineville(EveleighYard)SydneyTrainsconstructedan11kVcablerouteinsideEveleighYardforfeeders512and515.Partofthisrouteinvolvesanunderlinecrossing(ULX)belowseventracksinsidethemaintenanceyard.ThemaintenanceyardisathoroughfarefortrainsheadingintoandoutofSydneyforroutinemaintenance,whichincludesbothmetroandcountrytrains.Assuch,theseventrackshadlivetraintrafficduringtheunderborethataddedanotherlevelofcomplexitytotheunderboringprocess.UEAimplementeda

methodologyforundertakingtheprojectthatrequiredacombinationofmixedworkinghoursandavarietyoftechniquesthatmadetheinstallationofconduitssimpleamongthelimitationsofthesite.TECHNICALDETAILSUEA’steamwastaskedwiththeconstructionoftheunderborerequiredforthisproject.Workingwiththebriefprovidedby theclient,UEAundertookanadditional topographical surveyof theproposed route todevelop a comprehensive underbore design for each section. This enabled the design in both plan andlongitudinal cross-sectional views inMGA coordinates. Jemenawas consulted due to the vicinity of theSecondaryGasMain(SGM)inHaberfield,andwhileworkingwiththeJemenaGasProtectionofficers,theSGMwaspositively identifiedusingNon-DestructiveDigging techniques.Once located,asteelprotectionplate was installed in front of the SGM, in line with Jemena’s guidelines and UEA’s underboringmethodology. Upon approval of the underbore designs, UEA completed surveying tomark and peg outeachoftheunderborealignments.A Track SedimentMonitoringProgramwas required for twoof threeof the completedunderbores. Theunderboredesignsprovidedthedatarequiredtodevelopandimplementtheprogram,inwhichanumberofmonitoringtargetsareplacedinkeypositionsonandaroundthetrackalongtheunderboreroutespriortothecommencementofwork.Thisallowsaremotemonitoringstationtobesetupnearby, inordertoestablishabaselineofdatashowingthepreconstructionlevelsofthetracksandsurroundingsurfaces.Theremote monitoring station was utilised to constantly record readings before, during and after theunderboringworks.As part of the Track SedimentMonitoringProgram,UEAengaged a trackprotectionofficertoallowtheteam’sHDDoperativestotracktheunderboreacrossliverailtrackssafely.Workswerecompletedpredominatelyoutsideofatrackpossession,sotrainswerestillactiveacrossthenetwork.EachsitehadlimitedaccessaswellasalimitedareatosetuptheHDDrigandassociatedequipment.Asaresult,theweldingandstringingoftheHDPEelectricalconduitshadtotakeplaceadjacenttothesiteitself.On completionof the conduitwelding,UEAused custom-made spacers to formabundle ready for pipepull.Duetothecombinationofsoftclayandrockgroundconditionsforthefirsttwounderbores,UEAhadtheflexibility to use a second HDD rig and a variety of associated tooling. While working on the thirdunderbore, fill groundconditionswasencountered,whichcomplicated the removalofmaterial from theboreholeduringthereamingprocess.Thisincludesmaterialsuchasballastandunusedtracksleepers.COMPLETIONUEA used the team’s own pipe rollers and highly skilled HDD operatives to minimise the risk of pipedamageduringpipepull.Takingintoconsiderationthetightprojectschedule,UEAmanagedtosuccessfullycomplete all three underbores while working through constant wet weather and changing groundconditions.