appendix l method statements
DESCRIPTION
Method StatementsTRANSCRIPT
CORRIBFIELDDEVELOPMENTPROJECT
OnshoreWorksGlengad
METHODSTATEMENTRev01
LVI,GLENGADCOMPOUNDSandACCESSROADCONSTRUCTION
ShellExplorationandProductionIrelandLtd.
DraftEnvironmentalManagementPlan
MethodStatement
Title:
DocumentNo:
Revision:01
LVI,GlengadCompoundsandAccessRoad
COR14OPSH0000EMP
Page 2 of 8
SUMMARY
The construction of the Landfall Value Installation (LVI) within a dished area will be facilitated by the
establishment of a construction compound. This compound will also facilitate the onshore works
associated with the umbilical installation, onshore pipeline construction, and pipeline commissioning. A
second compound will be established to construct the reception shaft for the Tunnel Boring Machine
(TBM)1.ApermanentaccessroadtotheLVIwillalsobeconstructed.
PURPOSE
This method statement defines the method for the construction of the LVI,
establishing the Glengad construction compounds and permanent LVI access
roadatGlengad.
GlengadHeadland.Thetemporaryworkingareafromchainage83.3883.92
lieswithintheGlenamoyBogComplexcandidateSpecialAreaofConservation
(cSAC) Site Code 0000500 and is adjacent to the Blacksod Bay/Broadhaven
proposed Special Protection Area (pSPA) Site Code 004037. The northern
sectionoftheaccessroadfromtheL1202isalsointhecSAC.
ThehabitatslocatedwithinthetemporaryworkingareasatGlengadcomprise
improved agricultural grassland and improved wet, rushy grassy grassland,
neitherofwhichareEUannexedhabitats.
Withtheexceptionofthesouthernsectionofthereceptionshaftcompound,
thesehabitatsarelocatedwithinthecSAC.
Theentireworkscopewilltakeapproximately26months.TheLVIconstruction
compoundwillbeinoperationfortheentiredurationoftheonshorepipeline
construction including LVI surface water outfall pipe installation, LVI
construction, Umbilical pullin, onshore pipeline construction, tiein of the
onshoreandoffshorepipelineandfinalcommissioningactivities.
EstablishmentofGlengadCompounds
Thecompoundswillbeinstalledasfollows:
A 3m high palisade fence will be erected on grassland and secured by
concreteroadbarriers.
In designated sections the perimeter fence will be screened with a
suitablesolidboardtovisuallyandacousticallyscreentheworksinorder
tominimisedisturbancetobirdsandnonavianfauna.
Apalisadefencefixedtoprecastconcreteslabswillbepositionedonthe
foreshoretofacilitatetheLVIoutfallpipeinstallation.Thisfencewillbe
removed upon reinstatement of the cliff face and replaced with a land
basedfenceinstalledalongthetopofthecliff.
The temporary fences around the construction compounds and the LVI
willbemammalproof.
A temporary access road and hardstand areas will be constructed using
locallysourcedimportedgravel/stone.
Temporary welfare facilities will be installed on prepared ground
separate from the main working areas. Containers will be positioned as
requiredwithinthecompound.
All necessary electrical/telecom wiring, site services, lighting, piping,
ductingandfixtureswillbeinstalled.
LOCATION
HABITATS/
CONSERVATIONSTATUS
TIMESCALE
TECHNIQUE
ShellExplorationandProductionIrelandLtd.
DraftEnvironmentalManagementPlan
MethodStatement
Title:
DocumentNo:
Revision:01
LVI,GlengadCompoundsandAccessRoad
COR14OPSH0000EMP
Page 3 of 8
EarthworksandCivilWorks
TopsoilwillbestrippedfromLVIlocationandstockpiledinadesignated
locationseparatefromsubsoilandotherexcavatedmaterial.
Thedishedareawillbeexcavated,andthematerialstockpiledseparate
totopsoil.
IndividualLVIstructureswithindishedareawillbeexcavated.
ConstructionofLVIstructures,pipelineandancillaryservicesinstallation
willbecompletedsimultaneously.
Once all installation, inspection and testing has been completed, all
structureswillbebackfilledtotheirdesignatedfinishedlevels.
Permanentfencingandassociatedsecuritysystemswillbeerected.
Topsoil will be placed on new embankment slopes. An open mesh
biodegradable textile (GeoJute) maybe used on the slopes surrounding
theLVItostabilisetopsoilagainsterosion.
LVIMechanical,ElectricalandCommissioningworks
The piping, valves, structures, and chambers will be erected on the
preparedLVIfoundations.
TherelevantLVIcomponentswillbewelded/jointedandinspected.
TheoffshorepipelinewillbeconnectedtotheLVI.
TherequiredLVIandpipelinecommissioning,includinghydrotesting,will
takeplacewithintheconstructioncompound.
OffshoreUmbilicalInstallation(OnshoreWorks)
The compound will also be used to support the offshore umbilical pull
ashore.
Prior to the pull ashore a winch base will be constructed and winch
installed. This winch will be used to pull the offshore umbilical line
throughtheexistingumbilicalconduittoaterminationpointonshoreat
theLVI.
Following the pull ashore the umbilical will be monitored and tested
duringoffshoreinstallation.
Followingtheoffshorelayoftheumbilical,theonshorewinchandbase
willberemovedandareareinstated.
Reinstatement
Thecompoundwillnotbereinstateduntiltheendoftheconstructionperiod
however,somereinstatementwilltakeplacepriortothisifprogressallows.In
general,reinstatementwillprogressasfollows:
Excess materials from the excavation of the LVI dished area will be
reusedelsewhereifpossibleandthesurplusremovedtoalicensedwaste
facility.
ConstructpermanentaccessroadtoLVIusingthespecifiedmixofstone
andsoil.
Removetemporaryfacilities.
Thesitewillbereinstatedusingthestockpiledtopsoilandvegetationwill
beallowedtoregeneratenaturally.Noseedwillbeimported.
Alldrainswillbereinstatedtotheirpreviousconditionor,asagreedwith
ShellExplorationandProductionIrelandLtd.
DraftEnvironmentalManagementPlan
MethodStatement
Title:
DocumentNo:
Revision:01
LVI,GlengadCompoundsandAccessRoad
COR14OPSH0000EMP
Page 4 of 8
therelevantparties.
Whereappropriate,simple,surfacegravelfielddrainswillbeputinplace
topreventwaterlogging.
The temporary palisade fencing will then be removed off site and stock
prooffencingwillbeerectedtoprotectthereinstatedareas.
EQUIPMENT/MATERIALS
Excavators
Articulatedflatbedsandtipper
trucks
Fronttippingtrucks
Temporarywelfarecabins
Palisadesecurityfence
Winchesandhydraulicpower
packs
Hydrotestequipment
Cranesandliftingequipment
Sidebooms
Concretepump
Electricaltools
Weldingequipment
Syntheticfabrics
Commissioningplantand
equipment
Storagetanks
RESTRICTIONS
Some sections of the temporary working area lie within the Glenamoy Bog
Complex Complex cSAC and adjacent to the Blacksod Bay/Broadhaven
BaypSPA
Generalworkinghoursarerestrictedtobetween07:0019:00weekdays
and07:00and16:00Saturday.
Noiseandvibrationlimits
Lightingconstraints
Excavatedmaterialmayhavetobescreenedforpotentialreuse.
CONTINGENCY
1
See Tunnelling Operations and Reception Shaft Method Statements
ShellExplorationandProductionIrelandLtd.
DraftEnvironmentalManagementPlan
MethodStatement
Title:
DocumentNo:
Revision:01
LVI,GlengadCompoundsandAccessRoad
COR14OPSH0000EMP
Page 5 of 8
POTENTIALENVIRONMENTAL MITIGATION
IMPACT
Noise and vibration will be minimised through design, and
Noise,vibrationandlighting
appropriatesectionofplantandmachinery.
Disturbance.
Proactivemaintenanceofplantandequipment.
Claddingofstationarymachinerysuchasgenerators.
A 3m high nontransparent noise barrier will be installed in
designated places around the perimeter of the construction
compoundstopreventdisturbancetobirdsinthepSPA.
Mobile and fixed site lighting will be designed to limit light
spillage.
Roads/working area will be dampened down, as required to
ensure dust levels due to construction activities are kept to a
minimum.
Increaseddustlevels
ShellExplorationandProductionIrelandLtd.
DraftEnvironmentalManagementPlan
MethodStatement
Title:
DocumentNo:
Revision:01
LVI,GlengadCompoundsandAccessRoad
COR14OPSH0000EMP
Page 6 of 8
POTENTIALENVIRONMENTAL MITIGATION
IMPACT
Damagetohabitats,including AccessRoad
cSAChabitats
Thesodbankwhichformstheboundaryontheeasternsideof
the access road (from the public road) will be fenced off to
protect it from damage during construction. Any temporary
wideningoftheaccessroadwillbedoneonthewesternside.
LVIandGlengadCompounds
Anearthen(sod)bankformsthecSACboundarytothesouthof
the temporary working area adjacent to the LVI and onshore
pipeline temporary working area. This sod bank will be fenced
offtopreventconstructionactivitiesencroachingonit.
Fencing will be put in place to protect the Annex 1 habitats
locatedtothenorthofthecompounds.
Noseedwillbeimportedinordertopreventthepollutionofthe
nativegenepoolbyaliengenotypes.
Thetopsoilremovedfromthefootprintandcompoundswillbe
carefullystored(separatelyfromthesubsoil).
Followingconstructionthistopsoilwillthenbeusedontheareas
tobereinstated,includingtheslopesoftheLVIandtheywillbe
lefttorevegetatenaturally.
To aid topsoil stability and vegetation regeneration, an open
mesh geotextile membrane (GeoJute) may be laid on the side
slopesoftheLVIexcavation.
Surfacedrainagewillbeputinplaceatthetimeofreinstatement
topreventwaterloggingwhereappropriate.
Stoneusedwillbelocallysourced.
ShellExplorationandProductionIrelandLtd.
DraftEnvironmentalManagementPlan
MethodStatement
Title:
DocumentNo:
Revision:01
LVI,GlengadCompoundsandAccessRoad
COR14OPSH0000EMP
Page 7 of 8
POTENTIALENVIRONMENTAL MITIGATION
IMPACT
Groundnestingbirds
DisturbancetoBirds
Priortoconstruction,thetemporaryworkingareawillbemowed
in order to discourage ground nesting birds from attempting to
breedonthetemporaryworkingarea.
A walkover survey will be undertaken prior to construction in
order to ensure that no ground nesting birds are present on
landstobedisturbed.
SandMartin
A Sand Martin colony is located in the soft cliffs to the north and
north east of the landfall at Glengad. Mitigation measures as
outlinedbelowwillbeputinplace.
An exclusion zone will be defined above and behind the
colonysuchthatnoconstructionactivitiesaffecttheexisting
burrows or threaten the stability of the cliff in which the
burrowsaresituated.
Apartfromspecialistsconductingmonitoring,nopersonnel,
traffic or construction activities will be permitted between
the temporary fencing and the clifftop directly above the
colony.
Soil stockpiles will be covered where necessary with a fine
mesh netting to prevent sand martins from making nest
burrowstherein.
Lightinginsitecompoundswillbedirecteddownwardsand
be designed to minimise light spillage outside the working
area.
pSPA
Visualandacousticscreeningwillbeplacedonthepalisadefence
indesignatedplacestopreventdisturbancetobirdsinthepSPA.
Lightingwillbedirecteddownwardsandbedesignedtominimise
lightspillageoutsidetheworkingarea.
ShellExplorationandProductionIrelandLtd.
DraftEnvironmentalManagementPlan
MethodStatement
Title:
DocumentNo:
Revision:01
LVI,GlengadCompoundsandAccessRoad
COR14OPSH0000EMP
Page 8 of 8
POTENTIALENVIRONMENTAL MITIGATION
IMPACT
The palisade fence around the LVI and reception shaft
Constructionactivitiesmay
compoundswillbemammalproof.
havenegativeimpactonlocal
wildlife(ottersandbadgers
Theremainderofthefencingdemarkingthetemporaryworking
etc).
area, including the access road, will have mammal gates at the
base at 75m intervals. These will allow mammals (otters and
badgersetc)freeaccessacross,andameansofescapefrom,the
temporaryworkingarea.
Duringconstructionrampswillbeprovidedatopentrenchesto
provide a means of escape for otters and badgers and other
wildlife.
Machinery and plant will be inspected prior to mobilisation to
site.
Refuellingofplant/machinerywilltakeplaceindesignatedareas
only.
Spillkitswillbeavailableonsite
The LVI surface water outfall pipe will not be used for
dewateringofexcavations.
A surface water management system will be utilised to ensure
removal of suspended solids prior to discharge to receiving
watersatanagreedlocation.
Surfacedrainagewillbeputinplaceatthetimeofreinstatement
topreventwaterloggingwhereappropriate.
The LVI will be constructed in a dished area to reduce visual
impactofstructure.
Alicensedarchaeologistwillbeonsitetomonitorallexcavations
inpreviouslyundisturbedareas.
Pollutionofterrestrial/
aquatichabitatsdueto
spillageorleaksofoil/diesel
fromplantandequipment.
Releaseofsuspendedsolids
fromtheworksmayhave
negativeimpactonwater
quality.
VisualimpactfromtheLVI
structure.
Earthworksmaydisturb
archaeologicalremains.
CORRIBFIELDDEVELOPMENTPROJECT
OnshoreWorksGlengad
METHODSTATEMENTRev01
LVISurfaceWaterOutfallPipeandCliffReinstatement
ShellExplorationandProductionIrelandLtd.
DraftEnvironmentalManagementPlan
MethodStatement
Title:
DocumentNo:
Revision:01
LVISurfaceWater Outfall
COR14OPSH0000SEPILEMP
Page 1 of 5
SUMMARY
TheLandfallValveInstallation(LVI)SurfaceWaterOutfallwillbeconstructedbyexcavatingatrenchand
installing the pipe, headwall and gabion basket structure within the cliff face. The cliff face will be
subsequentlyreinstatedandtheoutfallpipetrenchbackfilledwithexcavatedmaterial.
PURPOSE
LOCATION
ThisdocumentdefinesthemethodforinstallationoftheLVIsurfacewater
outfallpipeandsubsequentreinstatementofthecliffsectionatGlengad.
Glengad Headland. The temporary working area from Chainage 83.38
83.50 lies within the Glenamoy Bog Complex candidate Special Area of
Conservation (cSAC) and the Blacksod Bay/Broadhaven proposed Special
ProtectionArea(pSPA).
Habitatscomprisenonannexedimprovedagriculturalgrassland(clifftop),
reinstatedsedimentarycliff;uppershoreline;andnonqualifyingintertidal
AnnexIhabitat(1140Mudflatsandsandflatsnotcoveredbyseawaterat
lowtide).
Theworkswilltakeapproximately8weekstocomplete,timedsothatthe
worksassociatedwiththeclifffacewillbeundertakenbetweenApriland
September.ThisistoavoiddisturbancetofeedingBrentGeeseduringthe
overwintering period. The remaining works will take place outside this
timeperiod.
LVIOutfallPipeTrenchandCliffExcavation
Temporary site palisade fencing will extend through the cliff cut and
extend onto a limited section of the foreshore (Ch 83.38
approximately).
A trench will be excavated from the cliff face and material will be
stored temporarily within the Glengad compound for reinstatement.
Thismaterialwillalsobeusedtoformasuitableaccessrampontothe
foreshorefortheinstallationofthesurfacewateroutfallpipe.
The excavation of the trench in the cliff face may be up to 5.5m in
depth and up to 15m wide. All trench arisings will be temporarily
storedintheGlengadcompound.
ThetrenchwillbeexcavatedtowardstheLVI,slopingtrenchsidesas
necessary.
Insectionsofrestrictedworkingareaorwheregroundconditionsare
poor,thesurfacewateroutfallpipewillbelaidusingatrenchboxor
supportstructure.
InstallationofPipeHeadwallandGabionBasketStructure
The headwall will be constructed by means of hand filled gabion
basketsaroundtheoutfallpipeblendedintotheexistingcliffface.
Ageotextileseparationlayerwillbeplacedatthebaseofthecliffface,
on top of which a headwall will be constructed using gabion
mattressesandbaskets.
The baskets will be filled with locally sourced stone to maximise the
integration of the headwall with the existing cliff and surrounding
environment.
HABITATS/
CONSERVATIONSTATUS
TIMESCALE
TECHNIQUE
ShellExplorationandProductionIrelandLtd.
DraftEnvironmentalManagementPlan
MethodStatement
Title:
DocumentNo:
Revision:01
LVISurfaceWater Outfall
COR14OPSH0000SEPILEMP
Page 2 of 5
The area in front of the headwall will be reinstated with locally
sourcedstonechosento maximisetheintegration oftheoutfallwith
theexistingcliffandsurroundingenvironment.
InstallationofLVIsurfacewateroutfallpipe
TheLVIsurfacewateroutfallpipewillbeplacedinsectionsandjoined
inthepreparedtrench.
TheLVIsurfacewateroutfallpipewillbebackfilledaftertesting.
The backfill material shall consist of compacted fine material with
progressive layers of excavated material being utilised to complete
trenchbackfill.
CliffandTrenchReinstatement
The cliff face will be reinstated once the outfall pipe installation has
progressed an adequate distance from the cliff to enable full cliff
reinstatement.
As the gabions are installed the cliff material will be compacted in
layersprogressingtooriginalgroundlevel.Thesubsoilwillbegraded
toreflecttheoriginalcontoursoftheheadland.
Geotextile may be required on steep sections of the cliff to prevent
winderosionandsiltrunoff.
The foreshore area will be reinstated to the highest achievable
standardwithmaximumreuseoforiginalforeshorematerial.
Surplusforeshorematerialwillbereusedordisposedofatalicensed
facility.
Anysurplusimportedrockwillberemovedoffsiteforreuse.
Thetemporaryfencingwillberemovedfromtheforeshoreduringcliff
reinstatement.
A stock proof fence will be erected on the cliff top for protection of
peopleandlivestock.
ShellExplorationandProductionIrelandLtd.
DraftEnvironmentalManagementPlan
MethodStatement
Title:
DocumentNo:
Revision:01
LVISurfaceWater Outfall
COR14OPSH0000SEPILEMP
Page 3 of 5
EQUIPMENT/MATERIALS
Excavators
Articulatedtippertrucks
Fronttippingtrucks
Cranes
WeldingEquipment
PallisadeFencing
SurfaceWaterOutfallPipe
GabianBasketsandlocally
sourcedstone
Syntheticfabrics
RESTRICTIONS
CONTINGENCY
TheworkingarealieswithintheGlenamoyBogComplex
BlacksodBay/BroadhavenBaycSPA4037
Normalworkinghoursarerestrictedtobetween07:0019:00weekdays
and07:00and16:00Saturday.
NoiseandvibrationlimitsLightingconstraints.
A rock breaker mounted on an excavator, maybe required to achieve the
required depth for the LVI outfall pipe or the LVI outfall pipe termination
gabioninstallation.
ShellExplorationandProductionIrelandLtd.
DraftEnvironmentalManagementPlan
MethodStatement
Title:
DocumentNo:
Revision:01
LVISurfaceWaterOutfall
COR14OPSH0000SEPILEMP
Page 4 of 5
POTENTIALENVIRONMENTAL MITIGATION
IMPACT
Noise,vibrationandlighting Noise and vibration will be minimized through design, and
appropriateselectionofplantandmachinery.
Disturbance.
Proactivemaintenanceofplantandequipment.
Claddingofstationarymachinerysuchasgenerators.
Screening will be placed on the palisade fence in designated
placestopreventdisturbancetobirdsinthepSPA.
Mobile and fixed site lighting will be designed to limit light
spillage.
Roads/working area will be dampened down, as required to
ensure dust levels due to construction activities are kept to a
minimum.
No machinery or personnel will be permitted outside the
temporary fencing on the foreshore with the exception of
specialistswhoareconductingmonitoring/surveywork.
Works will be restricted to the section of cliff which was
reinstated in 2009. Fencing will protect the previously
undisturbed cliff on either side of the currently reinstated
sectionofcliff.
Sediment/pollutantrunoffcontrolmeasures(seebelow)willbe
implemented to minimise impact on shoreline, intertidal and
marinehabitats.
Imported stone, including that used for cliff reinstatement, will
belocallysourced.
Preconstruction surveys for otters and badgers will be
undertaken within 13 months prior to construction. The areas
to be included are approximately 50100m either side of the
centrelineofthepipelineforotters,and30meithersideofthe
centrelineforbadgers.
Wildlife will be excluded from the temporary works area by
meansofmammalprooffencing.
Increaseddustlevels
Damagetohabitatsinthe
cSACandpSPA
Constructionactivitiesmay
havenegativeimpactonlocal
wildlifeottersandbadgers.
ShellExplorationandProductionIrelandLtd.
DraftEnvironmentalManagementPlan
MethodStatement
Title:
DocumentNo:
Revision:01
LVISurfaceWaterOutfall
COR14OPSH0000SEPILEMP
Page 5 of 5
POTENTIALENVIRONMENTAL MITIGATION
IMPACT
Groundnestingbirds
DisturbancetoBirdsandthe
pSPA
Prior to construction a walkover survey will be undertaken to
checkforgroundnesting birdsandthetemporaryworkingarea
onshorewillbemowedtodiscouragethesebirds.
A walkover survey will be undertaken prior to construction in
order to ensure that no ground nesting birds are present on
landstobedisturbed.
SandMartin
A Sand Martin colony is located in the soft cliffs to the north and
north east of the landfall at Glengad. Mitigation measures as
outlinedbelowwillbeputinplace.
An exclusion zone will be defined above and behind the
colonysuchthatnoconstructionactivitiesaffecttheexisting
burrows or threaten the stability of the cliff in which the
burrowsaresituated.
Apartfromspecialistsconductingmonitoring,nopersonnel,
trafficandconstructionactivitieswillbepermittedbetween
the Temporary Working Area fencing and the clifftop
directlyabovethecolony.
Awideforeshoreexclusionzonewillbeinplacetoprevent
any activity on the foreshore below and in front of the
burrowswhichmaydeternormalbehaviourandcouldresult
inloweredbreedingsuccess.
Soil stockpiles will be covered where necessary with a fine
mesh netting to prevent sand martins from making nest
burrowstherein.
Lighting will be directed downwards and designed to
minimiselightspillageoutsidetheworkingarea.
Acoustic&visualscreeningofconstructionactivitieswillbe
inplace.
ShellExplorationandProductionIrelandLtd.
DraftEnvironmentalManagementPlan
MethodStatement
Title:
DocumentNo:
Revision:01
LVISurfaceWaterOutfall
COR14OPSH0000SEPILEMP
Page 6 of 5
POTENTIALENVIRONMENTAL MITIGATION
IMPACT
BrentGeese
BrentGeeseoverwinterinthepSPAfromOctobertotheendofApril
andfeedonalgalbedsadjacenttotheGlengadlandfallsite.
Construction activities for the LVI outfall, including cliff
reinstatement works will be carried out during summer
monthsandoutsidetheoverwinteringperiod.
Pollutionofterrestrial/
aquatichabitatsdueto
spillageorleaksofoil/diesel
fromplantandequipment.
Machinery and plant will be inspected prior to mobilisation to
site.
Refuellingofplant/machinerywilltakeplaceindesignatedareas
only.
Refuellingwillnottakeplaceontheforeshore.
Spillkitswillbeavailableonsite.
Asmuchaspossible,constructionworksassociatedwiththecliff
cut will be carried out during low tide or neap tides to prevent
inundation and subsequent mobilisation of sediment into the
marineenvironment.
In drain mitigation will be placed as required to reduce silt
impactonassociatedsurfacewaters.
TheLVIsurfacewateroutfallwillnotbeusedfordewateringof
excavationsduringconstructionworks.
A surface water management system will be utilised to ensure
removal of suspended solids prior to discharge to receiving
watersatanagreedlocation.
Pumpedwaterwillbesubjecttosedimentcontrolmeasures.
Releaseofsuspendedsolids
fromtheworkscouldhave
negativeimpactonwater
quality.
Earthworksmaydisturb
archaeologicalremains
Alicensedarchaeologistwillbeonsitetomonitorallexcavations
inpreviouslyundisturbedareas.
CORRIBFIELDDEVELOPMENTPROJECT
OnshoreWorksGlengad
METHODSTATEMENTRev01
ONSHOREPIPELINECONSTRUCTION(Glengad)
ShellExplorationandProductionIrelandLtd.
DraftEnvironmentalManagementPlan
MethodStatement
Title:
DocumentNo:
Revision:01
OnshorePipelineConstructionGlengad
COR14OPSH0000SEPILEMP
Page1 of 6
SUMMARY
Thismethodstatementoutlinesthemethodologyfortheconstructionofonshoregaspipelineandservices
from the tie in of the offshore pipeline to the Landfall Valve Installation (LVI) and from the LVI to the
tunnelreceptionpit.
PURPOSE
Thismethodstatementdefinesthemethodologyforconstructionofthepipeline
andservicesinGlengad,toincludepreparationofthepipelinetemporaryworking
area,pipelineinstallationandreinstatement.
Glengad Headland, between chainage 83.49 and 83.86. Most of the temporary
working area is within the Glenamoy Bog Complex candidate Special Area of
Conservation (cSAC). It is in close proximity to the Blacksod Bay/Broadhaven
proposedSpecialProtectionArea(pSPA).
The habitats located within the temporary working areas at Glengad comprise
improvedagriculturalgrasslandandimprovedwet,rushygrassygrassland,neither
ofwhichareEUannexedhabitats.
With the exception of a short section of the pipeline route, these habitats are
locatedwithinthecSAC.
Preparation of the temporary working area and construction of the pipeline are
expected to take approximately two months. It should be noted that the
temporaryworkingareawillremainfencedoffuntilthecompletionoftunnelling
operationstofacilitateremovalofthetunnelboringmachine(TBM)andtoallow
connectionofthepipewithinthetunneltothepipelaidonshore.
TemporaryWorkingAreaPreparation
The temporary working area will be fenced off using 3m high palisade
fencing.
Indesignatedsectionsonthenorthernsideoftheworks,theperimeter
fencewillbescreenedwithasuitablesolidboardtoprovideavisualand
acousticscreen.
Topsoil within the temporary working area will be stripped and
stockpiledonsite.Subsoilwillbestockpiledseparately.
Anyearthen(sod)bankstobeimpactedwillbecarefullydismantledwith
the surface sods being stored separately and maintained during
construction. Those earthen (sod) banks which do not require to be
dismantledwillbefencedofftoprotectthemfromconstructiontraffic.
A running track, consisting of geotextile overlaid with materials
excavated during LVI construction and/or locally sourced stone, will be
constructedtoallowaccessforconstructionplant.
Drains within the temporary working area will be identified by marker
posts
Interceptor drains and flume pipes will be installed, as necessary, to
isolateanddivertsurfacewaterarisingoffsitetoreceivingwaters.
LOCATION
HABITATS/
CONSERVATION
STATUS
TIMESCALE
TECHNIQUE
ShellExplorationandProductionIrelandLtd.
DraftEnvironmentalManagementPlan
MethodStatement
Title:
DocumentNo:
Revision:01
OnshorePipelineConstructionGlengad
COR14OPSH0000SEPILEMP
Page2 of 6
Limitedaccessacrossthetemporaryworkingareaforlandownerswillbe
provided for by agreement with the landowner and when construction
worksallowsafeaccess.
PipelineConstruction
Allpipelineswillbestrungout,weldedandtestedpriortoexcavatingthe
trench.
Thepipelinetrenchwillbeexcavatedandthematerialstockpiledonsite.
Should any distinct layers in the subsoil be encountered, they will be
excavatedandstockpiledseparately.
The excavated trench will be dewatered if required, from asump box at
thelowestpoint.
Thepipesectionswillbeloweredintothetrenchbymeansofsidebooms
and inspected and backfilled with selected imported material. The main
body of the trench will be backfilled with materials excavated from the
trench.Allsoillayerswillbereinstatedinreverseordertothemannerin
whichtheywereexcavated.
Reinstatement
As stated previously, the temporary working area and running track will be
maintaineduntilaftercompletionofthetunnelandassociatedtieinworks.Some
reinstatementofthepipelinetrenchmaybepermittedafterpipelineinstallation.
Finalreinstatementwillbeasfollows;
Thetemporaryrunningtrackwillberemovedoffsiteforreuse,if
appropriateanditsroutereinstated.
Thesitewillbereinstatedusingthestockpiledtopsoilandvegetationwillbe
allowedtoregeneratenaturally.Noseedwillbeimported.
Alldrainswillbereinstatedtotheirpreviousconditionorasagreedwiththe
relevantparties.
Whereappropriate,simple,surfacegravelfielddrainswillbeputinplaceto
preventwaterlogging.
Earthen(sod)bankswillbefullyreinstated.
Thetemporarypalisadefencingwillthenberemovedoffsiteandstockproof
fencingwillbeerectedtoprotectthereinstatedareas.
Note:AllmovementofmaterialswillbethroughtheGlengadcompoundentrance.
ShellExplorationandProductionIrelandLtd.
DraftEnvironmentalManagementPlan
MethodStatement
Title:
DocumentNo:
Revision:01
OnshorePipelineConstructionGlengad
COR14OPSH0000SEPILEMP
Page3 of 6
EQUIPMENT
Excavators
ArticulatedDumptrucks
TrackedDumpers
Sidebooms
Some sections of the temporary working area lie within the Glenamoy Bog
ComplexCandidatecSACandareadjacenttoBlacksodBay/BroadhavenBaypSPA.
Construction works will be sequenced to facilitate the early commencement
ofreinstatementworksifpossible.
Normal construction work is restricted to between 07:00 19:00 weekdays
and07:00and16:00Saturday.
Noiseandvibrationlimits.
Lightingconstraints.
RESTRICTIONS
ShellExplorationandProductionIrelandLtd.
DraftEnvironmentalManagementPlan
MethodStatement
Title:
DocumentNo:
Revision:01
OnshorePipelineConstructionGlengad
COR14OPSH0000SEPILEMP
Page4 of 6
POTENTIAL
ENVIRONMENTAL
IMPACT
Noise,vibrationand
lightingDisturbance.
MITIGATION
Noiseandvibrationwillbeminimised through design,andappropriate
selectionofplantandequipment.
Proactivemaintenanceofmachinerytominimisenoiseandvibration.
Claddingofstationarymachinerysuchasgenerators.
Acousticscreening&fencingtominimisenoise.
Siteandmobilelightingwillbedesignedtolimitlightspillage.
Roads/workingareawillbedampeneddown,asrequiredtoensuredust
levelsduetoconstructionactivitiesarekepttoaminimum.
Fencing will be put in place to protect the Annex 1 dune grassland
locatedtothenorthoftheproposedpipelineroute.
Thetopsoilremovedwillbecarefullystored(separatelyfromthesub
soil)inordertomaintaintheseedbank.
Noseedwillbeimportedtopreventpollutionofthenativegenepoolby
aliengenotypes.
Sod banks impacted by construction will be carefully dismantled and
reinstatedbyhand.
Increaseddustlevels
Damagetohabitats,
includingthoseinthe
cSAC
ShellExplorationandProductionIrelandLtd.
DraftEnvironmentalManagementPlan
MethodStatement
Title:
DocumentNo:
Revision:01
OnshorePipelineConstructionGlengad
COR14OPSH0000SEPILEMP
Page5 of 6
POTENTIAL
ENVIRONMENTAL
IMPACT
DisturbancetoBirdsand
thepSPA
MITIGATION
Groundnestingbirds
Prior to construction, the temporary working area will be mowed in
order to discourage ground nesting birds from attempting to breed on
thetemporaryworkingarea.
A walkover survey will be undertaken prior to construction in order to
ensure that no ground nesting birds are present on lands to be
disturbed.
SandMartin
ASandMartincolonyislocatedinthesoftcliffstothenorthandnortheast
of the landfall at Glengad. Mitigation measures as outlined below will be
putinplace.
Anexclusionzonewillbedefinedaboveandbehindthecolonysuch
that no construction activities affect the existing burrows or
threatenthestabilityofthecliffinwhichtheburrowsaresituated.
Apart from specialists conducting monitoring, no personnel, traffic
or construction activities will be permitted between the fenced
temporaryworkingareaandtheclifftopdirectlyabovethecolony.
Soil stockpiles will be covered where necessary with a fine mesh
nettingtopreventsandmartinsfrommakingnestburrowstherein.
Lighting will be directed downwards and be designed to minimise
lightspillageoutsidetheworkingarea.
pSPA
At the northern side of the pipeline works, visual and acoustic
screeningwillbeplacedonthepalisadefenceindesignatedplaces
topreventdisturbancetobirdsinthepSPA.
Lighting will be directed downwards and be designed to minimise
lightspillageoutsidetheworkingarea.
ShellExplorationandProductionIrelandLtd.
DraftEnvironmentalManagementPlan
MethodStatement
Title:
DocumentNo:
Revision:01
OnshorePipelineConstructionGlengad
COR14OPSH0000SEPILEMP
Page6 of 6
POTENTIAL
ENVIRONMENTAL
IMPACT
Constructionactivities
mayhavenegative
impactonlocalwildlife.
MITIGATION
Preconstruction fauna surveys will be undertaken within 13 months
priortoconstruction,includingforottersandbadgers.Theareastobe
includedfor these twospeciesareapproximately;50100meitherside
ofthecentrelineofthepipelineforotters,and30meithersideofthe
centrelineforbadgers.
Duringconstruction,rampswillbeprovidedatopentrenchestoprovide
a means of escape for otters and badgers and other wildlife. Mammal
gates will be provided at the base of the fencing at 75m intervals to
allowottersandbadgersfreeaccessacross,andameansofescapefrom
theTemporaryWorkingArea.
Machineryandplantwillbeinspectedpriortomobilisationtosite.
Refuellingofplant/machinerywilltakeplaceindesignatedareasonly.
Spillkitswillbeavailableonsite.
The LVI outfall will not be used for discharge from dewatering of
excavationsduringconstructionworks.
Asurfacewatermanagementsystemwillbeutilisedtoensureremoval
ofsuspendedsolidspriortodischargetoreceivingwatersatanagreed
location.
Pumpedwaterwillbesubjecttosedimentcontrolmeasures.
Surface drainage will be put in place at the time of reinstatement to
preventwaterloggingwhereappropriate.
A licensed archaeologist will be on site to monitor all excavations in
previouslyundisturbedareas.
Pollutionofterrestrial
andaquatichabitatsdue
spillageorleaksof
oil/dieselfromplantand
equipment.
Releaseofsuspended
solidsfromtheworks
mayhavenegative
impactonwaterquality.
Earthworksmaydisturb
archaeologicalremains.
CORRIB FIELD DEVELOPMENT PROJECT
Onshore Works Aughoose
METHOD STATEMENT Rev 1
Aughoose Compound Construction
Shell E&P Ireland Ltd.
Draft Environmental Management Plan
Method Statement
Title:
Document No:
Revision: 01
Aughoose Compound Construction
COR-14-OP-SH-0000 SEPIL EMP
Page 1 of 9
SUMMARY
The works involve the erection of security fencing, site enabling works and all associated works to facilitate
the erection and construction of various temporary structures required to service the tunnelling
operations and subsequent pipeline installation.
PURPOSE
This method statement outlines the general method and sequence for installation
of all temporary structures and services required for tunnelling. Actual tunnel
operations and launch shaft construction is detailed elsewhere.
Aughoose Compound, pipeline chainage 88.67 to 89.11. The Aughoose Compound
is adjacent to the Glenamoy Bog Complex cSAC (Site Code 000500) and the
Blacksod Bay/Broadhaven pSPA (Site Code 004037).
Habitats comprise non-annexed modified blanket bog habitats, eroding blanket
bog and cutover. They do not form part of any designated conservation site.
Approximately 6-8 months to construct the compound which will be operational
for a further 20 months depending on seasonal reinstatement. Construction of a
2nd entrance (Access B) will take place approximately 10 months after the main
entrance is constructed.
The construction of the temporary compound comprises a number of main
construction operations; security fencing, entrance road construction, services
installation, initial welfare area construction, peat/stone handling area
construction, peat stockpiling, shear key construction, settlement pond
construction, site drainage installation, bulk earthworks, flexible pavement
construction, rigid pavement construction, retaining wall construction and
acoustic barrier construction. These operations are completed generally as
follows;
Security Fencing
A 3m high palisade fence is to be erected along the site boundary with the
L1202. This will involve a period of temporary traffic control to facilitate
this operation. All traffic control measures will be in accordance with
Chapter 8 of the Dept. of Transport Traffic Signs Manual and will be of
short duration.
A 3m high palisade fence situated on bog mats will be used where the site
boundaries are on peat (east, north and western sides).
In designated sections, the perimeter fence will be fitted with a suitable
solid board liner to visually and acoustically screen the works in order to
minimise disturbance to birds in the pSPA and otters on shorelines and
along the Leenamore River.
LOCATION
HABITATS /
CONSERVATION
STATUS
TIMESCALE
TECHNIQUE
Entrance Road Construction
The site entrance road will be constructed using the stone road method of
peat replacement/displacement with selected imported locally sourced
stone.
The stone road will consist of a peat stone matrix (approximately 0.5m of
peat left insitu with a 300mm to 500mm single size stone pushed into it,
Shell E&P Ireland Ltd.
Draft Environmental Management Plan
Method Statement
Title:
Document No:
Revision: 01
Aughoose Compound Construction
COR-14-OP-SH-0000 SEPIL EMP
Page 2 of 9
forming a peat stone matrix).
Starting at the L1202 (incorporating the traffic control measures in
Chapter 8 of the Dept. of Transport Traffic Signs Manual) the road
construction will proceed northwards into the site.
All excavated peat will be placed directly into the peat storage area and
spread as required.
The initial 50m will consist of a widened site entrance to facilitate the
correct sightlines and a double gate security system for deliveries, visitors,
etc.
The entrance road will be widened inside the 2nd access gate to allow
laden vehicles turn around once they have passed through the gate. This
widened area will be removed once the entrance road opens out into the
peat handling area.
The stone road construction operation will also involve a temporary
surface water treatment system involving the construction of lined v*
shaped drainage channels, temporary settlement lagoons and a mobile
settlement/treatment unit. All surface water runoff from the stone road
construction will flow through the water treatment system prior to
discharge to the existing surface water ditch.
A secondary entrance (Access B) will also be constructed using a
temporary bog mat access from the peat handling area. A temporary
ramp will be installed to allow vehicular access from Access B onto the
L1202. For the initial construction phase of the project, Access B will only
be used in the case of emergency.
* V-ditches will be lined with impermeable high density polyethylene (HDPE) liner.
Services Installation
Trenches will be excavated within the site roads to facilitate the
installation of a surface water collection system, a watermains and
ducting for temporary power and telecoms.
All services will be installed to relevant engineering standards using an
open trench method in the installed stone road.
Services will be continuously tested and backfilled as excavation
progresses using the same materials excavated.
Peat/Stone Handling Area
In order to facilitate the export of peat to Srahmore a specific vehicle
turning and loading area (peat/stone handling area) will be constructed to
separate road traffic from site traffic.
Peat excavated from various locations of the site will be transported to
this location.
Peat suitable for stockpiling will be separated from peat which is to be
transported to Srahmore.
Part of this area will also be used for stockpiling stone used in
Shell E&P Ireland Ltd.
Draft Environmental Management Plan
Method Statement
Title:
Document No:
Revision: 01
Aughoose Compound Construction
COR-14-OP-SH-0000 SEPIL EMP
Page 3 of 9
construction operations.
A wheel wash facility will be installed in this area.
Initial Welfare Area Construction
The initial welfare area and materials laydown area will be constructed
within the peat handling area on the north-west side of the main access
road.
Welfare facilities will consist of toilets, offices, drying rooms, storage
containers, waste compactors and skips, canteens and bunded chemical
stores.
Peat Stockpiling
The peat from the surface of the site (generally 0.6 m), including the
surface vegetation, will be stockpiled onsite for reinstatement after
tunnelling completion.
It should be noted that an additional quantity of peat will be stored onsite
for reinstatement of locations where mineral soil will be excavated.
Peat stockpiling will involve the construction of a temporary bog mat
access into the designated areas.
Peat stored in the peat handling area will be transferred to the peat
storage area.
The vegetation layer will be placed (roots downwards) on top of the stored
peat so that it can continue to grow during storage and be available for
subsequent reinstatement.
The bog mat access will be removed as the area fills and will be reinstalled
again during reinstatement operations.
Shear Key Construction
In order to mitigate against geotechnical risks associated with peat
excavation (e.g. slippage of peat), a shear key will be installed around the
perimeter of the tunnelling compound by means of the stone road
method.
This will be completed prior to any excavation of the main body of peat
from the tunnel compound.
Peat excavated during shear key construction will be brought to the peat
handling area prior to stockpiling in the peat storage area or transport to
Srahmore.
Settlement Lagoon Construction
Prior to excavation of the main body of peat (bulk earthworks), a
settlement lagoon will be constructed at the low point of the site.
The lagoon will be constructed and lined/sealed with a HDPE liner. All
water collected in the various drainage ditches and pipes will flow to this
lagoon.
Shell E&P Ireland Ltd.
Draft Environmental Management Plan
Method Statement
Title:
Document No:
Revision: 01
Aughoose Compound Construction
COR-14-OP-SH-0000 SEPIL EMP
Page 4 of 9
An additional water tank will be constructed at the same time as the
settlement lagoon to provide additional storage capacity if required.
Settlement ponds will be covered by firm wire mesh (WeldMesh) of small
enough mesh size to prevent access to birds.
Site Drainage Installation
A surface water drainage system will be installed in the roads, shear keys
and main site as each section of works progresses.
The drainage system will consist of gullies, underground pipework,
manholes and a number of lined open ditches.
This system will collect all rainwater by gravity flow to the settlement
lagoon, passing through a bypass separator.
Acoustic Barrier Construction
The entire tunnelling compound will be surrounded by an acoustic fence.
Acoustic fence construction will progress in conjunction with shear key
construction.
This fence will be in place prior to commencement of bulk earthworks.
Bulk Earthworks
Once the shear keys, settlement lagoon and overground water storage
tank have been installed bulk excavation of the main body of peat will
commence.
This will be completed by means of excavators and dumptrucks and will
coincide with the replacement of the peat by imported fill.
In general, an approximate 0.5m depth of peat will be left insitu to form
the peat stone matrix, the surface peat will be stored onsite and the
remainder transported off site.
The peat will be completely removed where required in settlement critical
locations.
Flexible Pavement Construction
A flexible bitumen bound surface will be constructed over the majority of
the site (i.e access roads, shear keys etc).
This flexible pavement will consist of imported stone and bitumen bound
macadam materials to NRA specifications.
This will provide an impervious surface to reduce run off from the stone
roads and will provide an easily maintained clean surface for tunnelling
works.
Rigid Pavement Construction
In certain locations on the site the standard flexible pavement will be
replaced by a rigid pavement.
Shell E&P Ireland Ltd.
Draft Environmental Management Plan
Method Statement
Title:
Document No:
Revision: 01
Aughoose Compound Construction
COR-14-OP-SH-0000 SEPIL EMP
Page 5 of 9
The rigid pavement will be constructed from reinforced concrete and will
generally form foundations and bunded areas at various locations.
Retaining Wall Construction
At various locations retaining walls will be installed where a level platform
or a gradual fall is required for tunnelling works.
These walls will be constructed from precast items where possible for
future recycling. Where precast structures cannot be used, in situ concrete
walls will be constructed.
Stringing Area
Once tunnelling operations commence the stringing area construction can
begin.
This will be completed by means of excavators and dumptrucks and will
coincide with the replacement of the peat by a mixture of tunnel arisings
and imported fill.
In general, an approximate 0.5m depth of peat will be left in situ to form
the peat stone matrix, the surface peat and vegetation layer will be stored
on site, as for the tunnelling compound, and the remainder transported off
site.
A stone road will be constructed from the stringing area over to access B,
replacing the original bog mat emergency access. This road will be
constructed 10 months after initial site mobilisation.
Reinstatement
Once all tunnelling, pipelaying, testing and commissioning are complete
the entire compound will be reinstated with a layer of peat which was
previously stored in the peat storage area.
All construction materials that can be reused (fencing, bogmats, precast
retaining walls, underground pipework, etc.) will be carefully dismantled
and transported off site.
Other materials such as surplus stone will be returned to local quarries or
used elsewhere in the locality if possible.
Materials which cannot be immediately reused (i.e. tarmacadam, concrete
etc) will be transported to a recycling facility.
Any materials which do not fit the above criteria will be removed to a
licenced waste facility.
In locations where peat was entirely removed during construction (e.g
crane locations) the imported fill will be excavated and a 1m layer of peat
will be installed on top of the mineral soil level and the fill placed back on
top of this peat layer again.
The top 300mm to 500mm of stone will be excavated and removed off
site.
Finally, the entire area will be covered with a layer of peat from the peat
storage area with the site being returned to its original levels in
preparation for habitat restoration.
Shell E&P Ireland Ltd.
Draft Environmental Management Plan
Method Statement
Title:
Document No:
Revision: 01
Aughoose Compound Construction
COR-14-OP-SH-0000 SEPIL EMP
Page 6 of 9
EQUIPMENT
The surface vegetation layer will then be reinstated under the direction of
the Project Ecologist.
Once the area is reinstated, the original drainage system will be reinstated
and the perimeter security fence will be removed off site.
Stock proof fencing will be erected to protect the reinstated areas.
LGP ExcavatorsTracked Excavators
Articulated DumptrucksWheeled Excavators
Front Loading DumpersTracked Dumpers
Articulated Trucks (road going)Road sweepers
Water BowsersTractors
RollersVibrating wackers
Concrete pumpsCranes
LoadallsGenerators
Lighting towersPavers
Chip spreadersTar sprayers
Tack coatersPitch cart
Thermoplastic lining trucks
Turving bucket (for use during reinstatement)
Working adjacent to:
Blacksod Bay/Broadhaven pSPA.
Glenamoy Bog Complex cSAC.
Normal construction work will take place between 07:00 and 19:00
weekdays and 07:00 and 16:00 on Saturday. Only essential works will
carried out between the hours of 19:00 and 07:00.
Noise and vibration limits.
Lighting constraints.
RESTRICTIONS
Shell E&P Ireland Ltd.
Draft Environmental Management Plan
Method Statement
Title:
Document No:
Revision: 01
Aughoose Compound Construction
COR-14-OP-SH-0000 SEPIL EMP
Page 7 of 9
POTENTIAL
ENVIRONMENTAL
IMPACT
Noise, Vibration,
Lighting - Disturbance
MITIGATION
Noise and vibration will be minimized through design, and appropriate
selection of plant and equipment.
Proactive maintenance of plant and machinery.
Cladding of stationary machinery such as generators.
A 3m high non-transparent noise barrier will be installed around the
perimeter of the tunnelling compound.
Mobile and fixed site lighting will be designed to limit light spillage.
Roads/working area will be dampened down, as required to ensure
dust levels due to construction activities are kept to a minimum.
Robust measures (see below) will be implemented to prevent
sedimentation and pollution of the adjacent Annex I estuarine and
interidal habitats in Sruwaddacon Bay and species which depend upon
them, including salmon.
Increased dust levels
Potential for indirect
impact on habitats and
species in the adjacent
cSAC /pSPA
Direct impact on
habitats as a result of
construction activities
Habitat reinstatement and vegetation restoration
During the initial site establishment works, plant material will be
harvested from areas which will be impacted during construction. This
will be removed from the site for propagation and for use during
reinstatement.
The surface layer of peat will be stored on site. The stripped vegetation
layer will be placed, right way up roots downwards, on top of the
peat in the peat storage areas for use in reinstatement.
If required, stored peat will be covered with Geo-jute to stabilise it and
to encourage vegetation growth following storage.
During re-instatement, the entire area will be re covered with a layer of
peat, and the vegetation from the top of the peat storage areas will be
replaced under direction from the Project Ecologist.
A phased re-instatement programme will be undertaken over 1 to 5
years.
Once the reinstated peat has stabilised, peat forming conditions will be
created by means of pool creation and Sphagnum inoculation.
Native scrub species will be planted in places in the reinstated peat
storage areas.
Fencing for the tunnelling compound will be fully wildlife proofed to
prevent mammals entering site.
Acoustic and visual screening on fences will minimise disturbance to
otters on shorelines of the bay.
During construction, ramps will be provided at any open trenches
accessible to wildlife to provide a means of escape.
Work activities will be limited to between the hours of 07:00 and 19:00.
Night caps will be placed over all pipe ends.
Construction activities
may affect local wildlife
(otters and badgers)
Shell E&P Ireland Ltd.
Draft Environmental Management Plan
Method Statement
Title:
Document No:
Revision: 01
Aughoose Compound Construction
COR-14-OP-SH-0000 SEPIL EMP
Page 8 of 9
POTENTIAL
ENVIRONMENTAL
IMPACT
Construction activities
may affect amphibians
MITIGATION
Any frogs (adults, spawn and tadpoles) identified prior to, and during,
construction will be translocated under licence to a suitable location.
Habitat reinstatement will re-create the former channel and drain
systems so that frogs may use these post construction.
Acoustic screening barriers will be installed on the temporary
perimeter palisade fencing.
Solid acoustic fencing will be used within the compound to minimise
noise.
Lighting will be designed to minimise light leakage into the pSPA (light
intensity no more than 0.3 lux at the shoreline).
Green (beacon) lighting will be installed on tall structures and uprights
to reduce collision risk.
Settlement ponds will be covered by firm wire mesh (WeldMesh) of
small enough mesh size to prevent access to birds.
Robust sediment and pollution control measures to prevent impact on
prey species in the Bay (benthic macrofauna and fish species).
A walkover survey will be undertaken prior to construction in order to
ensure that no ground nesting birds are present on lands to be
disturbed.
Vegetation restoration and planting of native scrub species during
reinstatement.
Machinery and plant will be inspected prior to mobilisation to site.
Refuelling of plant/machinery will only take place in designated areas.
Spill kits will be available on site.
Disturbance to birds in
the adjacent pSPA and
birds on migration
Disturbance to birds in
the locality (other than
in the pSPA)
Pollution of
Land/Water/ cSAC and
pSPA habitats & species
due spillage or leaks of
oil/diesel from plant
and equipment
Release of suspended
solids from the works
could have negative
impact on water
quality, cSAC and pSPA
habitats & species
therein including
salmon
The surface water treatment system will comprise a bypass separator
for removal of hydrocarbons followed by a settlement lagoon for
removal of suspended solids and the installation of a filtration system
for finer particles.
V-ditches will be installed up slope and down slope of peat storage
areas.
In drain mitigation will be placed as required to reduce silt impact on
associated waterways.
Culverts will be placed at locations where access roads must cross
existing drains and ditches.
Concrete wash system will be installed.
Wheel wash system will be installed.
Pumped water will be subject to sediment control measures.
Any concrete poured in situ will be covered to prevent run off during
rainfall as per industry best practice.
Shell E&P Ireland Ltd.
Draft Environmental Management Plan
Method Statement
Title:
Document No:
Revision: 01
Aughoose Compound Construction
COR-14-OP-SH-0000 SEPIL EMP
Page 9 of 9
POTENTIAL
ENVIRONMENTAL
IMPACT
Change in local
hydrology/hydro-
geological regimes.
MITIGATION
An approximate 500mm depth of peat will be left in situ to form a peat
stone matrix in all areas except those classified as settlement critical.
The stone for constructing the stone road will be locally sourced and
carefully selected to ensure that it is appropriate for the local
environment within the peat.
A licensed archaeologist will be on site to monitor all peat excavation
and tunnelling activities.
Works may disturb
archaeological remains
CORRIB FIELD DEVELOPMENT PROJECT
Onshore Works Aughoose
METHOD STATEMENT Rev 01
Construction of Start Shaft and Ramp
Shell Exploration and Production Ireland Ltd.
Draft Environmental Management Plan
Method Statement
Title:
Document No:
Revision: 01
Construction of tunnel start shaft and ramp
COR-14-OP-SH-0000_SEPIL EMP
Page 1 of 5
SUMMARY
This document defines the construction methodology and sequence of works for the construction of the
starting shaft and ramp in the Aughoose Compound, for the Corrib Onshore PIpeline. In order to facilitate
commencement of the tunnelling works it is necessary to excavate a shaft and ramp into which the Tunnel
Boring Machine (TBM) will be lowered. The TBM will be lowered in sections into the shaft/ramp for
assembly prior to commencement of tunnelling.
PURPOSE
The start shaft and ramp will provide the commencement point for tunnelling works
and will serve as the main access corridor between the tunnel and the surface for
transport of material, plant and labour into and out of the tunnel.
The start shaft and ramp will be located in the Aughoose Compound at chainage
88.77. The start shaft is approximately 18m long x 9m wide and 12m deep, the
adjoining ramp is approximately 75m long x 6m wide and ranging in depth from 6m to
12m below ground level. The Aughoose Compound is adjacent to the Glenamoy Bog
Complex cSAC (Site Code 000500) and the Blacksod Bay/Broadhaven pSPA (Site Code
004037).
The habitat present at the starting shaft is non-annexed eroding blanket bog. The
Aughoose compound is not in any designated conservation site.
The duration of construction of the start shaft and ramp is approximately six to seven
months. It is anticipated that construction will take place in 2011/2012.
The construction of the start shaft and ramp is based on the use of a sheet piling
system with the placement of concrete for support in the lower part of the
excavation.
Under this method of construction the sequence of construction would be as follows:
In the deeper parts of the start shaft/ramp, where it is required to install
sheet piles through bedrock, the bedrock will be pre-drilled in order to
facilitate the installation of the piles.
Piles will then be installed to the required depth using appropriate drilling
and driving equipment.
Commence with initial excavation of material from within the footprint of
the sheet piles (to an initial depth of approximately 2m below the original
ground level).
Install upper level props or anchors as required to brace the sheet piles.
Continue with excavations down to bedrock level.
Install anchors at low level as required to brace the sheetpiles.
Commence with breaking and excavating of bedrock to the required level.
Place and construct reinforced concrete support in the lower part of the
excavation.
Construction of the TBM soft eye / sealing body.
Piling Works
The ground conditions expected to be encountered in the construction of the
LOCATION
HABITATS /
CONSERVATION
STATUS
TIMESCALE
CONSTRUCTION
METHODOLOGY
Shell Exploration and Production Ireland Ltd.
Draft Environmental Management Plan
Method Statement
Title:
Document No:
Revision: 01
Construction of tunnel start shaft and ramp
COR-14-OP-SH-0000_SEPIL EMP
Page 2 of 5
shaft/ramp will consist of an upper layer of engineering fill, mineral soil and
overlying bedrock. It is expected that bedrock will be encountered along the
entire length of the start shaft and ramp. As such the rock will be required to be
predrilled prior to the installation of the piles.
The size and geometry of the piles installed through the bedrock will be varied to
suit the installation process and the requirements of the detailed design. Where
piles are installed into bedrock it is envisaged that the piles will terminate below
the base of the excavation.
Following the initial installation of the piles, excavation will commence. As these
progress the sheet piles will have to be propped. To do this a series of walers will
be lifted into position inside the excavation and secured in place onto the
sheetpiles once the upper 2m of excavation has been carried out.
Where upper level anchors are required in the walls then they will be installed
prior to the positioning of the walers and later tensioned following the
installation of the walers. Lower level anchors may also be required depending
upon the outcome of the detailed design.
Excavations
Upon installation of the sheet piles it will be required to excavate the material
from within the area enclosed by the sheet piles. Excavation will be carried out in
various stages. Initially, the upper 2m of material will be removed using an
excavator(s) after which a series of struts/wailers will be installed to support the
upper level of the sheet piles. The struts will act as props spanning across the
excavation props will be secured to walers placed on the face of the sheet piles
within the excavation.
If necessary, a series of anchors will be installed as described above. Excavations
will then re-commence and be progressed down to bedrock.
Where bedrock level is reached within the excavation it may be necessary to
install additional anchors through the sheet piles in order to ensure the stability
of the sheet pile structure prior to works progressing deeper. These anchors will
be installed using a drill rig working within the excavation.
Following the installation of the anchors, excavation for the lower section of the
shaft/ramp will recommence. In order to remove the bedrock from the lower
level of the excavation, excavator(s) will be fitted with hydraulic breaker(s) which
will be used to break out the rock. Depending on the integrity of the rock
encountered additional excavation measures may be required (such as pre-
drilling) to facilitate the extraction/removal of rock.
As and when sufficient volumes of rock have been broken, an excavator(s) will
remove the broken rock from the excavation. A crane may also be utilised to assit
with the removal of rock from within the lower level of the shaft/ramp.
Groundwater ingress into the excavation will be controlled by pumping from
sumps located in the floor of the excavation. Water from pumps will be
Shell Exploration and Production Ireland Ltd.
Draft Environmental Management Plan
Method Statement
Title:
Document No:
Revision: 01
Construction of tunnel start shaft and ramp
COR-14-OP-SH-0000_SEPIL EMP
Page 3 of 5
discharged into the settlement lagoon or to an alternative temporary
storage/treatment facility, if necessary.
Excavated material brought to the surface will generally be loaded into a dump
truck and either reused on site or transported to a temporary stockpile within the
Aughoose compound from where it will be transported off site.
Placement of Concrete
Concrete will be required to support the piles in the lower part of the excavation
(through the bedrock) and also for the construction of the required slab at the
bottom of the excavation.
Upon completion of the excavation works to the required level, reinforced
concrete, 0.5 to 1.0 m thick will be constructed in situ at the bottom of the shaft
and ramp. To prevent uplift of the concrete it may be required to install a series
of rock anchors into the bedrock underlying the reinforced concrete slab. These
anchors will be installed using a drill rig working from within the partially
completed ramp/shaft excavation.
Low strength concrete will be used to form the TBM soft eye / sealing body.
Reinstatement
Once the onshore pipeline and associated services have been installed in the
tunnel and the tunnel fully grouted, the start shaft and ramp will be backfilled.
The pipeline and associated services will be backfilled with suitable bedding and
surround material.
The remaining excavation will be backfilled with suitable material compacted in
layers to within 1m of the underside of the original peat depth where a 1m layer
of low permeability reworked peat will be placed. Further backfilling of suitable
compacted material will continue to the underside of the surface reinstatement
layer, which will comprise peat.
As backfilling progresses upwards, sheet piles left in situ will be cut to a depth of
1m below finished ground level. Anchors used for bracing of the sheet piles will
be distressed and props/walers removed.
Reinstatement of the peat layer will be in accordance with the method statement
for the Aughoose Compound.
The surface vegetation layer will then be reinstated under the direction of the
Project Ecologist.
Piling rigs
Mobile cranes
Telehandlers/ Lifting and loading
devices
Excavators
Various pumps
Hydraulic breakers
Dump trucks
Rotary drilling equipment
Drilling rigs for anchor installation
Miscellaneous small tools
EQUIPMENT
Shell Exploration and Production Ireland Ltd.
Draft Environmental Management Plan
Method Statement
Title:
Document No:
Revision: 01
Construction of tunnel start shaft and ramp
COR-14-OP-SH-0000_SEPIL EMP
Page 4 of 5
RESTRICTIONS
Working adjacent to:
Blacksod Bay/Broadhaven pSPA
Glenamoy Bog Complex cSAC
Noise and vibration limits
Lighting constraints
Normal construction works will be restricted to between the hours of 07:00 and 19:00
weekdays and 07:00 and 16:00 Saturday.
POTENTIAL ENVIRONMENTAL
IMPACT
Noise, vibration and lighting.
MITIGATION
Noise and vibration will be minimised through design, and
appropriate selection of plant and equipment.
Proactive maintenance of machinery.
Cladding of stationary machinery such as generators.
Acoustic screening & fencing.
Site and mobile lighting will be designed to limit light spillage.
Roads/working area will be dampened down, as required to ensure
dust levels due to construction activities are kept to a minimum.
Robust measures (see below) will be implemented to prevent
sedimentation and pollution of the adjacent Annex I estuarine and
intertidal habitats in Sruwaddacon Bay and species which depend
upon them, including salmon.
Careful reinstatement of the area will be carried out following the
completion of the tunnelling works.
Habitat reinstatement and vegetation restoration will be carried out
as set in the Aughoose Compound Method Statement.
Mitigation measures, as set out for the Aughoose Compound as a
whole, will be implemented
Increased dust levels
Potential for indirect impact
on habitats and species in the
adjacent cSAC /pSPA
Direct impact on habitats as a
result of construction
activities
Disturbance to birds in the
adjacent pSPA and birds on
migration
Disturbance to birds in the
locality (other than in the
pSPA)
A walkover survey will be undertaken prior to construction in order
to ensure that no ground nesting birds are present on lands to be
disturbed.
Shell Exploration and Production Ireland Ltd.
Draft Environmental Management Plan
Method Statement
Title:
Document No:
Revision: 01
Construction of tunnel start shaft and ramp
COR-14-OP-SH-0000_SEPIL EMP
Page 5 of 5
Pollution of Land/Water/ cSAC
and pSPA habitats & species
due spillage or leaks of
oil/diesel from plant and
equipment.
Release of suspended solids
from the works could have
negative impact on water
quality, cSAC and pSPA
habitats & species therein
including salmon.
Machinery and plant will be inspected prior to mobilisation to site.
Refuelling of plant/machinery will take place in designated areas
only.
Spill kits will be available on site.
Groundwater which may ingress into the excavation will be
controlled by setting up temporary sumps in the floor of the
excavation to dewater the excavation. Pumped water will be subject
to sediment control measures.
A surface water managment will be utilised to ensure removal of
suspended solids prior to discharge to receiving waters at an agreed
location.
Please refer to the Aughoose Compound Method Statement
A licensed archaeologist will be on site to monitor all excavations in
previously undisturbed areas.
Earthworks may disturb
archaeological remains
CORRIB FIELD DEVELOPMENT PROJECT
Onshore Works Construction of Tunnel
METHOD STATEMENT Rev 01
Tunnelling Operations
Shell Exploration and Production Ireland Ltd.
Draft Environmental Management Plan
Method Statement
Title:
Document No:
Revision: 01
Tunnelling Operations
COR-14-OP-0000_SEPIL EMP
Page 1 of 6
SUMMARY
This document describes the construction of the 4.9km segment lined tunnel in which the Corrib Onshore
Pipeline between Glenagd and Aughoose will be installed.
PURPOSE
A 4.9km segment lined tunnel will be constructed using a Tunnel Boring Machine
(TBM) between Aughoose and Glengad.
The segment lined tunnel will be constructed from the starting shaft located at
Aughoose (approx. Chainage 88.77). From there, the pipeline route traverses
(underneath) the Glenamoy Bog Complex cSAC and the Blacksod Bay/Broadhaven
pSPA at Sruwaddacon Bay in a north-westerly direction towards Glengad for
approximately 4.9km, where the reception shaft (Chainage 83.88) will be
constructed in the cSAC. The tunnel will be constructed with a minimum depth of
cover of 5.5m.
It is anticipated that the tunnelling process will take approximately 15 months to
complete (at an average of 11m/ day).
The tunnelling construction will be carried out on a 24 hours a day/ 7 days a week
basis.
Other associated works, such as material transport and tunnel arisings disposal will
be executed between the hours of 07:00 and 19:00 weekdays and 07:00 and 16:00
Saturday.
CONSTRUCTION
METHODOLOGY
The scope of works for the construction of the segment lined tunnel can be
generally divided into the following work steps:
Construction of the 4.9km tunnel including access ramps, starting shaft
and reception shaft;
Installation and testing of the 20 inch gas pipeline and services in the
tunnel; and
Grouting of the tunnel and re-instatement of the shafts.
LOCATION
TIMESCALE
Further details on the construction of the start and reception shafts are provided in
other method statements.
Prior to the commencement of tunnelling, the Aughoose compound is
constructed and associated utility systems, e.g. an appropriate surface water
management system, are made available. A separate method statement
describes the construction of the Aughoose compound.
Plant and equipment required for the tunnelling, including the TBM, are then
mobilised to site.
All TBM assembly and material supply will be managed from the starting shaft
in Aughoose.
Shell Exploration and Production Ireland Ltd.
Draft Environmental Management Plan
Method Statement
Title:
Document No:
Revision: 01
Tunnelling Operations
COR-14-OP-0000_SEPIL EMP
Page 2 of 6
Plant and Equipment
The main plant and equipment required for the tunnelling process include:
Gantry crane;
Grout mortar Silos
Slurry treatment plant
Bentonite tanks and silos
Freshwater tank
Water storage tanks
Filter press
Power generation units
Following the installation of all the required plant and the set up of the site
compound and function testing the tunnelling process will commence.
Tunnel construction:
The tunnel will be constructed using a slurry shield tunnelling method which
involves the drilling/boring of the soil face using a TBM and then installing
precast concrete segments as the TBM progresses.
The cutting wheel at the front of the TBM tunnels into the ground. The TBM is
controlled by the steering cylinders within the TBM which pushes the cutter
head in the desired direction.
Power switchboards, hydraulic and logistic units are all installed near the TBM
on a number of back-up trailers. These trailers (typically of 8 10 m length) are
interconnected and pulled by the TBM through the tunnel.
Concrete segments are transported to the front of the tunnel on a train that
runs on tracks within the tunnel during construction. These tracks are installed
in parallel to the tunnelling operation on one of the TBM back-up trailers.
The stacked segments are transported through the tunnel to the tail skin by a
supply system with train cars and cranes. An erector unit located within the
TBM is used to pick up the segments from the train and it installs the segments
into the designated position. Once installed they are bolted to the already
installed ring and segments.
Concrete segments which are erected inside the back end of the tunnelling
machine (the tail skin) and assembled to form a complete segment ring which
is connected, grouted and when in position acts as the tunnel lining.
After completion of one segment ring, all jacking cylinders are extended for a
further advance cycle. By using this method of tunnel lining, the already built
concrete tunnel remains stationary and serves as an abutment for the advance
of the TBM. Grout (annulus grouting) is injected into the overcut behind the
installed segment rings, which is created by the cutting wheel during
excavation.
Shell Exploration and Production Ireland Ltd.
Draft Environmental Management Plan
Method Statement
Title:
Document No:
Revision: 01
Tunnelling Operations
COR-14-OP-0000_SEPIL EMP
Page 3 of 6
Slurry lines for spoil transport, air duct for ventilation, pressurised air supply
and power/communication cables are installed inside the tunnel to support
the drilling process.
Drilling fluid consisting of a suspension of water and bentonite (bentonite
slurry) is used for lubrication and cooling of the cutting head, removal of
cuttings and stabilisation of the cutting face.
Bentonite slurry suspension will be pumped through the feeding pipe into the
TBM working chamber. It is mixed with the excavated soil / rock and pumped
back through the slurry discharge pipe to the separation plant at Aughoose
Compound. The soil is separated and the recycled bentonite slurry suspension
pumped through the tunnel back into the TBM working chamber.
The excavated materials from tunnelling (tunnel arisings) is separated from the
drilling fluid/bentonite slurry mixture using a separation plant where shakers
are deployed and stockpiled temporarily within the Aughoose Compound in
designated area.
The surplus bentonite slurry will be removed and dewatered in a filter press.
After being treated in the filter press the filter cake is dry enough for
transportation to a licensed waste facility.
Mixing of Grout Mortar
Grout mortar will be used for grouting the annulus of the tunnel (voids behind
the segments). The grout mortar will also be used for filling the tunnel
following the installation of the pipeline and services.
Mixing of grout will take place in a controlled and contained environment
using automated mixing tanks located in the Aughoose Compound. Grout silos,
located adjacent to the mixing tanks, will be filled with dry cement brought in
by container truck. The cement will be blown into the storage silos from the
container truck using a sealed unit and stored there for mixing as required
during the works.
The mixing operation will involve the grouting mix and water. This is then
pumped in containers which are transferred to the tunnel using the tunnel
railway.
To prevent ingress of water and grout into the TBM, brush seals between the
tail skin and the erected segments are filled with grease.
Demobilisation and Reinstatement:
When the TBM reaches the receiving shaft in Glengad, it will be recovered and
the installation of the gas pipeline and services can start. Installation of the
pipeline and services is from Aughoose.
Shell Exploration and Production Ireland Ltd.
Draft Environmental Management Plan
Method Statement
Title:
Document No:
Revision: 01
Tunnelling Operations
COR-14-OP-0000_SEPIL EMP
Page 4 of 6
Demobilisation of the TBM will be carried out at the Glengad site. Tunnelling
equipment, such as separation plant, bentonite treatment plant, grout silos,
etc. at the Aughoose Compound will be demobilised in stages upon completion
of the significant elements of the works.
Once the onshore pipeline and associated services have been installed in the
tunnel and the tunnel fully grouted, the start shaft and ramp will be backfilled.
Backfilling of the Tunnel & Pipeline Installation:
The grout mortar will also be used for filling the tunnel following the
installation of the pipeline and services.
The equipment associated with this backfilling operation will be located at the
Aughoose compound and the backfilling operation will be carried out from one
side only by pumping the backfilling mix through the pre-installed grouting.
EQUIPMENT
Tunnel boring machine (TBM)
TBM back-up system
Tunnel segments
Track and train system
Separation plant
Bentonite handling unit
Bentonite silos
Filter press
Supply system, feeding pipes / cables
Control Station
Lifting and loading devices
Tanks
Gantry crane
Mortar silos
RESTRICTIONS
Tunnel will be constructed underneath:
Blacksod Bay/Broadhaven pSPA
Glenamoy Bog Complex cSAC
Noise and vibration limits
Lighting constraints
Non-essential activities may require to be suspended at the Aughoose Compound
on Easter Sundays during periods when Mass is taking place at the nearby
commemorative site.
Shell Exploration and Production Ireland Ltd.
Draft Environmental Management Plan
Method Statement
Title:
Document No:
Revision: 01
Tunnelling Operations
COR-14-OP-0000_SEPIL EMP
Page 5 of 6
POTENTIAL
ENVIRONMENTAL
IMPACT
Release of bentonite to
environment
MITIGATION
The composition of slurry is designed to suit the geotechnical conditions.
Bentonite pressure and rate of usage will be monitored constantly. In the
event of bentonite release the bentonite operating pressure will be reduced
immediately to reduce bentonite loss.
Bentonite sensors will be installed in the excavation chamber. The chamber
can be separated from the slurry system.
The TBM speed will be altered to suit the ground conditions.
In the unlikely event of a bentonite release the design and operation of the
TBM will limit the volume to 7m3.
Measures will be implemented at Aughoose and Glengad to prevent any
egress of bentonite into watercourses leading into the cSAC /pSPA. A hard
standing area for bentonite handling plant will be located in the Aughoose
Compound. There is a separate drainage system where the run-off is
collected and pumped into a used bentonite tank. During removal of the
TBM at Glengad, the shaft will be partially flooded. This water will be
contained within the shaft and removed offsite for treatment at an
appropriate licensed water treatment facility. Robust measures will be
taken to ensure there is no bentonite release during the loading, handling
and transport of the TBM in Glengad.
Noise and vibration will be minimised through design, and appropriate
selection of plant and equipment.
Proactive maintenance of machinery.
Cladding of stationary machinery such as generators and separation plant.
Acoustic screening & fencing.
Site and mobile lighting will be designed to limit light spillage.
Noise, vibration and
lighting disturbance.
Shell Exploration and Production Ireland Ltd.
Draft Environmental Management Plan
Method Statement
Title:
Document No:
Revision: 01
Tunnelling Operations
COR-14-OP-0000_SEPIL EMP
Page 6 of 6
POTENTIAL
ENVIRONMENTAL
IMPACT
Disturbance to birds in
the adjacent pSPA and
birds on migration
MITIGATION
Acoustic screening barriers will be installed on the temporary perimeter
palisade fencing.
Solid acoustic fencing will be used within the compound to minimise noise.
Lighting will be designed to minimise light leakage into the pSPA (light
intensity no more than 0.3 lux at the shoreline).
Green (beacon) lighting will be installed on tall structures and uprights to
reduce collision risk.
Settlement ponds will be covered by firm wire mesh (WeldMesh) of small
enough mesh size to prevent access to birds.
Robust sediment and pollution control measures to prevent impact on prey
species in the Bay (benthic macrofauna and fish species).
See LVI, Glengad Compounds and Access Road MS for details of further
mitigation.
Robust measures (see below and Aughoose Compound Construction MS)
will be implemented to prevent sedimentation and pollution of the adjacent
Annex I estuarine and interidal habitats in Sruwaddacon Bay and species
which depend upon them, including salmon.
Machinery and plant will be inspected prior to mobilisation to site.
Refuelling of plant/machinery will take place in designated areas only.
Spill kits will be available on site.
A surface water management system will be utilised to ensure removal of
suspended solids prior to discharge to receiving waters at an agreed
location.
Pumped water will be subject to sediment control measures.
A licensed archaeologist will be on site to monitor all excavations of the
tunnel start and reception shafts.
In the event of an archaeological find the archaeologist may have work on
the site stopped, pending a decision as to how best to deal with the
archaeology by the Department of Arts, Heritage and Gaeltacht Affairs
(DAHGA) (previously assigned to the Department of Environment, Heritage
and Local Government (DoEHLG).
Potential for indirect
impact on habitats and
species in the adjacent
cSAC /pSPA
Pollution of
Land/Water /cSAC and
pSPA habitats & species
due spillage or leaks of
oil/diesel fro