Dublin Dredging MMO Report - dublinport.ie
Transcript of Dublin Dredging MMO Report - dublinport.ie
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MarineMammalObserverReport
Project:MaintenanceDredging,DublinPort
MarineMammalObserversReportforDredgingandDumpingActivity
June-July2016
Client:DublinPortCompany
ForeshoreLicense:AKC/2016/00262
DumpingatSeaPermit:S0004-01
EcologicalConsultants:IWDG
MarineMammalObservers:PaddyO’Dwyer,EndaMcKeogh,
ClodaghRussell,LoraineGrant,StephanieLevesque
IrishWhaleandDolphinGroup
MerchantsQuay,Kilrush,CoClare,Ireland
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ContentsExecutiveSummary..................................................................................................................3
DredgingReport.......................................................................................................................5
Dateandlocation.................................................................................................................5
MMOdetails.........................................................................................................................5
Otherplatform/vesselinvolvedintheoperation/activity...................................................6
Co-ordinatesfortheareasofoperationsmonitoredbyMMO............................................7
Observationplatform...........................................................................................................7
Detailsofsound-producingoperations................................................................................9
Detailsofmonitoringwatches.............................................................................................9
Detailsofallmarinemammalsightingsrecordedduringmonitoringwatches.................12
Detailsofallmarinemammalsightingsrecordedoutsidemonitoringwatches(e.g.,incidentalobservations),includingrecordsfromadditionalpersonnelonboard.............14
Detailsofanyproblemsencounteredduringmarinemammalmonitoring,start-upprocedures,ramp-up(soft-start)proceduresorduringfullscaleoperation/activity........14
Conclusions............................................................................................................................14
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ExecutiveSummaryThe IrishWhale and Dolphin Group (IWDG)were contracted by Dublin Port Company to
provide experiencedMarineMammalObserver’s formaintenance dredging and dumping
operationsinDublinBay,CountyDublin.Dredgingoperationstookplaceover42daysfrom
20thJuneto31stJuly2016.WherepossibleanMMOcarriedoutaminimum30minutesvisual
monitoring of a 500m exclusion zone for the presence of marine mammals before
commencementofactivities.
Therewere134sightingsofmarinemammalsduringthemaintenancedredgingcampaign.
Greyseal(Halichoerusgrypus)wasthemostcommonlyrecordedspecieswith76sightings
(57%)followedbyharbourporpoise(Phocoenaphocoena)with56sightings(42%).Therewas
onesightingofaharbourseal(Phocavitulina)andonesightingrecordedasunidentifiedseal
asspeciesidentificationwasnotpossible.Ofthe134sightingsrecorded,61%wererecorded
duringthewatchpriortothecommencementofdredginganddumpingoperations.
Atotalofthreedelaystooperationswereinstigatedbytheobservers,twoofwhichrelated
tomarinemammalsbeingpresent in themitigation zonewhile theotherwasdue to sea
conditionsnotbeingsuitableforconductingapre-watch.Inbothofthedelaysduetomarine
mammalbeingpresentinthemitigationzone,operationswereallowedtocommenceonce
theanimalhadleftthemitigationzone.
Therewere606pre-watchescarriedoutbyMMO’sduringtheproject,with54instancesof
operations commencing inpoorweather conditions (sea state>4) and the remaining552
occurring in suitable conditions (sea state <4). Additionally, there were 249 instances of
operationsstartingatnight.ItisgenerallyrecognizedthattheNPWSguidelinesneedtobe
reviewed in relation to dredging operations. The continuous nature of dredging activities
requiresoperationduringhoursofdarkness.Monitoringduringnighttimeoperationsusing
hydrophonescansupportmitigationmeasures.
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In the opinion of IWDG Consulting, it is highly unlikely that the dredging and dumping
activitieshadanysignificantimpactonmarinemammalsintheareaandatworstmayhave
causedtemporarydisplacementofsomeindividuals.
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DredgingReportDateandlocationImplementationofmarinemammalmitigationmeasurestookplaceon42daysfrom20thJune
to 31st July 2016 at Dublin Port in Dublin Bay, County Dublin to support a maintenance
dredgingcampaignbeingcarriedoutbyDublinPortCompany.Thedredgingareasincluded
numerous berths in the port downstream of Alexandra BasinWest, and inner and outer
navigationapproachchannels.ThedumpsitewaslocatedatBurfordbankapproximately5km
SouthofHowthhead.Thedumpsiteisapproximately12kmfromthewesternmostdredge
siteand4.5kmfortheeasternmostdredgesite.(SeeFigure1below.)
Figure1.Theareastobedredgedandspoilgroundsforthemaintenancedredgecampaign
(redboundarylines).
MMOdetailsThe marine mammal observer’s (MMO) who monitored the implementation of NPWS
guidelinesduringthedredginganddumpingwerePaddyO’Dwyer,EndaMcKeogh,Clodagh
Russell,LoraineGrantandStephanieLevesquewhoareallexperiencedJNCCtrainedmarine
mammal observers (See CV’s in Appendix I). Paddy O’Dwyer and Enda McKeogh were
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stationedonthedredgevesselthroughoutthecampaignwhiletheotherMMOsusedwere
stationedonlandatthedredgesite.
Otherplatform/vesselinvolvedintheoperation/activityThe Boskalis vesselMV Freewaywas contracted for the dredging operations. It is a 92m
trailingsuctionhopperdredgerwithacapacityof4,500m3(seeFigure2below).TheFreeway
canreleaseitsloadinapproximately30-40secondsfollowedbyafurtherfewminutestowash
outtheholdingtankandtofullyclosethedoors.
TheFreewaywassupportedbyvesselsoperatingploughsandbackhoestodistributeand
accesssedimentsfordredging.Theseoperatedcontinuouslywithintheportarea.Asurvey
vesselalsosupportedthedredgingprogrammeandoperatedthroughoutthearea.
Figure2.Trailingsuctionhopperdredger;MVFreeway
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Co-ordinatesfortheareasofoperationsmonitoredbyMMO
Table1.Co-ordinatesforareasofoperation
NorthQuayExtension FerryPort53'20.79' N 06'13.63' W 53'20.68' N 06'12.18' W53'20.78' N 06'13.63' W 53'20.70' N 06'12.19' W53'20.74' N 06'12.98' W 53'20.71' N 06'12.02' W53'20.73' N 06'12.98' W 53'20.88' N 06'12.00' W
SouthQuays 53'20.89' N 06'11.92' W53'20.64' N 06'12.89' W 53'20.80' N 06'11.87' W53'20.63' N 06'12.90' W 53'20.69' N 06'11.88' W53'20.55' N 06'11.87' W 53'20.71' N 06'11.57' W53'20.54' N 06'11.87' W 53'20.67' N 06'11.40' W
OilBerths 53'20.70' N 06'11.45' W53'20.69' N 06'12.45' W 53'20.75' N 06'11.49' W53'20.82' N 06'12.43' W 53'20.86' N 06'11.49' W53'20.85' N 06'12.39' W 53'20.88' N 06'11.58' W53'20.84' N 06'12.25' W Dumpingsite53'20.80' N 06'12.23' W 53'20.07' N 06'03.00' W53'20.69' N 06'12.24' W 53'20.07' N 06'01.82' W53'20.68' N 06'12.18' W 53'19.17' N 06'01.82' W
AlexandraBasinEast 53'19.17' N 06'02.71' W53'20.72' N 06'12.75' W 53'19.38' N 06'03.00' W53'20.69' N 06'12.45' W RiverAreaB53'20.82' N 06'12.43' W 53'20.65' N 06'09.00' W53'20.83' N 06'12.74' W 53'20.57' N 06'09.05' W53'20.72' N 06'12.62' W 53'20.72' N 06'12.75' W53'20.73' N 06'12.74' W 53'20.64' N 06'12.85' W
ObservationplatformAtotalofthreeMMO’swererequiredsimultaneouslytoimplementthemitigationguidelines
forthisproject.TwoMMO’sconductedwatchesfromthebridgeofthesourcevesselwhich
providedaviewingheightofapproximately7.5metersabovesealevelbutvariedsomewhat
dependingonwhetherthehopperisfullorempty.Landbasedobservationswerecarriedout
fromCoalpier(53012.10,-06005.35) inDublinPortandprovidedexcellentviewsintothe
variousquaysintheport(SeeFigure3below)whichweretobedredged.
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Figure3.Locationoflandbasedobserver(yellowpin).
The vessel based observers conducted watches from dawn to dusk while the land based
observerconductedwatches from08:30 to17:30.The landbasedobserverconductedpre-
watches for dredging in the harbour and inner channel areas only while the vessel based
observersmonitoredtheseareasinadditiontotheotherdredgesitesnotvisibletotheland
basedobserverandspoilgrounds.Thevesselbasedobserversconductedwatchesusing7*50
binocularswhilethelandbasedmonitoringwasconductedusinganOpticron30-70xtelescope.
Alldatawasrecordedontodataformsforcoastal/marineworkswhichweresourcedfromthe
National Parks andWildlife Services’ document; “Guidance toManage the Risk toMarine
Mammals fromManMade Sound Sources in IrishWaters” and later entered on an excel
spreadsheet.
Pre-startwatcheswere conductedduring transit between thedredgeanddump sites. This
resultedinmostofthepre-startwatchesfordumpingbeingapproximately20minuteslong
but reduced thedurationof theprojectbyover threedaysand so limited theexposureof
marinemammalsintheareatotheoperations.ThepresenceofathirdobserverbasedonCoal
pierintheharbourallowedforthemajorityofpre-watchesintheharbourandinnerchannel
tobe>30minutes’duration.
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However, it should be noted, as described above, that the dredging operations were
continuousinthesensethatthedredgerandsupportvesselsoperatedcontinuouslybetween
dredging and dump sites. Any pauses in the campaign due to bunkering or repairs were
preceded by 30minute pre-start watches. It was decided that all transits of the dredger
betweendredgesitesanddumpareawouldbeprecededbypre-startMMOwatches inthe
interest of best practice. Underwater noise monitoring undertaken during this dredging
campaignhasconfirmedthatnoiselevelsgeneratedbydredgingwerebelowthedisturbance
levelsformarinemammalsandfishat213mfromsource.Italsoconfirmedthatnoiselevels
generated by dredge spoil dumping operations, although slightly above the response
thresholds for harbour porpoise at 90m from source, are below the general behavioural
thresholdforharbourporpoiseatthisdistance.Itisclearthereforethattheimplementation
ofthe500mexclusionzoneduringthiscampaignisaneffectivemitigationmeasuretoprotect
marinemammals.
Detailsofsound-producingoperationsTherewasatotalof429dredgingoperationsand429dumpingoperationsduringtheproject.
Operationsran24hoursperdayand7daysaweekexceptduringbunkering/resupplyand
duringunexpectedbreakdowns.Table2belowprovidesasummaryofoperationsbutfull
detailscanbefoundinAppendixII.
Table2.Summaryofsoundproducingoperationsduringtheproject
Description Number Duration(hh:mm)Totaloperations 858 486:37:00
Totaldumpingactivities 429 60:18:00Totaldredgingactivities 429 426:19:00
DetailsofmonitoringwatchesAtotalof780hoursand34minutesofmonitoringeffortwascompletedduringtheproject.Of
this, transiting between the dump and dredge sites accounted for 54%, dredging activities
accountedfor40.6%anddumpingactivitiesaccountedfor5.4%(seeFigure4below).Atotal
of606pre-startmonitoringwatcheswerecarriedout (304of thesewereprior todredging
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operationsand302werepriortodumpingoperations).Fulldetailsofmonitoringeffortcarried
outduringthisprojectcanbefoundinAppendixIII.
Figure4.Percentageofmonitoringeffortconductedduringthedifferentoperationsstatus
Sightingsconditionsduringtheprojectweregenerallygoodbutperiodsofpoorweatherdid
occur.WindsrecordedduringobservationswerepredominantlyWestorSouth-westerly(see
Figure5below).
Figure5.Summaryofwinddirectionthroughoutobservations
41%
5%
54%
Operationstatusduringobservations
DREDGING
DUMPING
TRANSIT
051015202530
N
NE
E
SE
S
SW
W
NW
Winddirectionduringobservations
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Thevisibilitywashigh(>10km)forthemajorityofobservationsduringtheproject(96.5%).
Good visibility (5-10 km) accounted for 1.8% of observations, moderate visibility (1-5 km)
accountedfor1.3%andpoorvisibility(>1km)accountedfor0.4%ofobservations.SeeFigure
6below.
Figure6.Summaryofvisibilityduringtheproject.
Therewasnoswellforthemajorityofobservationsduringtheproject(82%ofobservations)
andlowswell(0-1m)for18%ofobservations.SeeFigure7below.
Figure7.Summaryofswellheightduringtheproject
0.4
1.3
1.8
96.5
Poor(>1km)
Moderate(1-5km)
Good(5-10km)
High(>10km)
VisibilityduringObservations
%
82%
18%
Swellheightduringobservations
Noswell 0-1m
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Seastatewasgoodforthemajorityofobservationsduringtheproject.Thevastmajorityof
observations(91%)werecarriedoutinaseastate<4while47%wascarriedoutinseastate
<2.Thehighestseastaterecordedwasseastate6andthisaccountedfor3%ofobservations.
SeeFigure8below.
Figure8.Summaryofseastateduringtheproject
Detailsofallmarinemammalsightingsrecordedduringmonitoringwatches.Therewere134sightingsofmarinemammalsondayswheredredginganddumpingactivities
tookplace.Theanimalswerewelldistributedwithsightingsoccurringatbothdumpanddredge
sitesaswellaswhiletransitingbetweenthese.Thegreysealwasthemostcommonlyrecorded
specieswith76sightings(57%)followedbyharbourporpoisewith56sightings(42%).There
wasonesightingofaharboursealandonesightingrecordedasunidentifiedsealasspecies
identification was not possible. The highest number of individuals recorded was harbour
porpoisewhichaccounted for approximately54%of the total numberof individualmarine
mammals sighted. Table 3 below is a summary of all sightings during the project but full
sightingsrecordscanbefoundinAppendixIV.
9%
38%
26%
18%
6%
3%
SeaStatesummaryduringproject
SS1 SS2 SS3 SS4 SS5 SS6
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Table3:Summaryofsightingsrecordedthroughouttheproject
Species Numberofsightings
Numberofindividuals Groupsize Adults Juveniles Calves
Greyseal 76 77 1-2 77 0 0Harbourporpoise 56 93 1-5 74 1 18Commonseal 1 1 1 1 0 0
Unidentifiedseal 1 1 1 1 0 0
Themajorityofharbourporpoisesightingswerewelldistributedthroughouttheoperational
areaoutsideoftheharbourwhileonlythreeharbourporpoisesightingsoccurredinsidethe
breakwaterwalls.Figure9belowshowsthedistributionofharbourporpoisesightingsduring
theproject.
Figure9.Thedistributionofharbourporpoisesightingsduringtheproject
Themajorityof seal sightingsoccurred inside thebreakwaterwalls.Allbut twoof the seal
sightings recordedwereofgreyseals. It is likely thatmanyof theseal sightings inside the
breakwater are duplicate sightings of the same animal at different times. Figure 10 below
showsthedistributionofsealsightingsduringtheproject.
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Figure10.Thedistributionofsealsightingsduringtheproject.Greenpointsrepresentgrey
seals,whitepointrepresentsacommonsealandthepurplepointrepresentsunidentified
seals.
Detailsofallmarinemammalsightingsrecordedoutsidemonitoringwatches(e.g.,incidentalobservations),includingrecordsfromadditionalpersonnelonboard.Therewasoneincidentalreportwhereasighting(129)wasrecordedbyalandbasedobserver
aftertheyhadcompletedtheirwatchbutremainedinthearea.
Table4:Summaryofincidentalobservations
Species Groupsize Adults Juveniles CalvesGreyseal 1 1 0 0
Detailsofanyproblemsencounteredduringmarinemammalmonitoring,start-upprocedures,ramp-up(soft-start)proceduresorduringfullscaleoperation/activity.Therewerenoproblemsencountered.
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ConclusionsA pragmatic best practice approach was taken towards implementing the mitigation
measures required for this project. Although dredging and associated activities were
continuousduringoperation,watcheswereundertakenduringdredgertransittoandfrom
the dump site. The transit timemeant watches were generally of 20 minutes’ duration.
Comparedtotherecommended30minutepre-watch,thisresultedinshorteningtheduration
of the project and exposure of marine mammals by over three days (75hrs 37mins). By
allowingoperations to commenceonce an animal had left themitigation zone insteadof
waitingafurther30minutes,thepotentialfordelayswerereducedandoveralldisturbance
totheanimalsminimised.
In the opinion of IWDG Consulting, it is highly unlikely that the dredging and dumping
activitieshadasignificant impactonmarinemammals in theareaandatworstmayhave
causedtemporarydisplacementofsomeindividuals.