appendix l method statements

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



MethodStatement

Title:

DocumentNo:

Revision:01


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



MethodStatement

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Revision:01


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



MethodStatement

Title:

DocumentNo:

Revision:01


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



MethodStatement

Title:

DocumentNo:

Revision:01


COR14OPSH0000EMP

Page 6 of 8


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.



MethodStatement

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DocumentNo:

Revision:01


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Page 7 of 8


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.



MethodStatement

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Revision:01


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Page 8 of 8


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.


OnshoreWorksGlengad


LVISurfaceWaterOutfallPipeandCliffReinstatement



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



MethodStatement

Title:

DocumentNo:

Revision:01



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.



MethodStatement

Title:

DocumentNo:

Revision:01



Page 3 of 5

EQUIPMENT/MATERIALS

Excavators

Articulatedtippertrucks

Fronttippingtrucks

Cranes

WeldingEquipment

PallisadeFencing

SurfaceWaterOutfallPipe

GabianBasketsandlocally

sourcedstone

Syntheticfabrics

RESTRICTIONS

CONTINGENCY

TheworkingarealieswithintheGlenamoyBogComplex

BlacksodBay/BroadhavenBaycSPA4037

Normalworkinghoursarerestrictedtobetween07:0019:00weekdays


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.



MethodStatement

Title:

DocumentNo:

Revision:01

LVISurfaceWaterOutfall


Page 4 of 5


IMPACT

Noise,vibrationandlighting Noise and vibration will be minimized through design, and

appropriateselectionofplantandmachinery.

Disturbance.

Proactivemaintenanceofplantandequipment.


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.



MethodStatement

Title:

DocumentNo:

Revision:01



Page 5 of 5


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.



MethodStatement

Title:

DocumentNo:

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Page 6 of 5


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.


archaeologicalremains

Alicensedarchaeologistwillbeonsitetomonitorallexcavations

inpreviouslyundisturbedareas.


OnshoreWorksGlengad


ONSHOREPIPELINECONSTRUCTION(Glengad)



MethodStatement

Title:

DocumentNo:

Revision:01

OnshorePipelineConstructionGlengad


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



MethodStatement

Title:

DocumentNo:

Revision:01



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.



MethodStatement

Title:

DocumentNo:

Revision:01



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


Noiseandvibrationlimits.

Lightingconstraints.

RESTRICTIONS



MethodStatement

Title:

DocumentNo:

Revision:01



Page4 of 6

POTENTIAL

ENVIRONMENTAL

IMPACT

Noise,vibrationand

lightingDisturbance.

MITIGATION

Noiseandvibrationwillbeminimised through design,andappropriate

selectionofplantandequipment.

Proactivemaintenanceofmachinerytominimisenoiseandvibration.


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



MethodStatement

Title:

DocumentNo:

Revision:01



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


pSPA

At the northern side of the pipeline works, visual and acoustic

screeningwillbeplacedonthepalisadefenceindesignatedplaces

topreventdisturbancetobirdsinthepSPA.

Lighting will be directed downwards and be designed to minimise




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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.


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


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,



Method Statement

Title:

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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



Method Statement

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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.



Method Statement

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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.



Method Statement

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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.



Method Statement

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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



Method Statement

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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)



Method Statement

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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


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.



Method Statement

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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


Onshore Works Aughoose


Construction of Start Shaft and Ramp

Shell Exploration and Production Ireland Ltd.


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



Method Statement

Title:

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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



Method Statement

Title:

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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



Method Statement

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Document No:

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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.



Method Statement

Title:

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Page 5 of 5

Pollution of Land/Water/ cSAC

and pSPA habitats & species


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.


Refuelling of plant/machinery will take place in designated areas

only.


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


Onshore Works Construction of Tunnel


Tunnelling Operations



Method Statement

Title:

Document No:

Revision: 01


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.



Method Statement

Title:

Document No:

Revision: 01



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.



Method Statement

Title:

Document No:

Revision: 01



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.



Method Statement

Title:

Document No:

Revision: 01



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.



Method Statement

Title:

Document No:

Revision: 01



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.



Method Statement

Title:

Document No:

Revision: 01



Page 6 of 6

POTENTIAL

ENVIRONMENTAL

IMPACT


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.


Refuelling of plant/machinery will take place in designated areas only.


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


oil/diesel fro

appendix l method statements

Documents