dredging in trinidad and tobago environmental considerations for ports

Dredging in Trinidad and Tobago.Environmental Considerations for

Ports

Judson Farray

Dredging in Trinidad and Tobago. Environmental Considerations for Ports

Published by Spree Spirit 2014 Trinidad & Tobago ! 1

Dredging(in(Trinidad(and(Tobago:(

Environmental(Considera5ons(for(Ports

By#Judson#Farray

Foreword#by:#Michele#de#Verteuil



©"2014"Spree"Spirit,"some"rights"reserved

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Non(Commercial."You"may"not"use"this"work"for"commercial"purposes

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Any"of"the"above"condiFons"can"be"waived"if"you"get"permission"from"the"copyright"holder."[email protected]"

ISBN"978U976U95675U1U1""|"Published"in"Trinidad"and"Tobago"""|"First"EdiFon

Figure"1:"A"clamshell"dredger"at"work



mailto:[email protected]

mailto:[email protected]

Acknowledgements

I"would"like"to"humbly"thank"the"late"Neil"Charles,"Marcia"Gomez,"Cyril"Collier,"Llewellyn"McIntosh,"George"

Alexis,"the"late"Garth"Marcelle,"Leonard"Chan"Chow"and,"as"always,"my"enFre"family"for"supporFng"me,"

giving"me"opportuniFes,"inspiring"me,"encouraging"me"and"indulging"me.



PrefaceThis " publicaFon" goes" into" slightly" more" technical" detail" than" the" more" rounded" ‘Guidelines" for"

Maintenance"Dredging" in"Trinidad"and"Tobago’."The"intenFon"of"this"publicaFon"is"to"acquaint"novice"port"

pracFFoners"with"some"of" the"environmental"terminology"used"and"to"describe"the"background,"processes"

and" challenges" of" performing" maintenance" dredging" by" a" high" profile," corporately" responsible" port"

operator"in"a"developing"country."The"reality"is"that,"the"Fme"taken"to"aHain"a"CerFficate"of"Environmental"

Clearance"is "unpredictable."It"has"become"necessary"for"port"pracFFoners"to"understand"the"sediment"and"

water" analysis "and" hydrographic" survey" reports" and," in" some" cases," to" do" the" research" to" assess " the"

environmental"impact"of"dredging"themselves"and"present"the"assessment"to"the"various,"relevant"internal"

and"external"authoriFes."

In"order" to"deal"with" the"specifics"of" acquiring"that"ability,"this"publicaFon"will"introduce,"as"background"

material," general" informaFon" about"Trinidad"and"Tobago" and" some"experiences"from" the"port"of" Point"

ForFn" specifically." The" issues" of" transparency," bureaucracy," environmentalism," some" of" the" technical"

aspects" of" dredging," dredging" equipment," disposal," the" composiFon" of" the" seabed" and" some" exisFng"

convenFons"on"environmental"protecFon"are"also"introduced.

While"some"technical"and"scienFfic"informaFon"is"included,"the"real"context"of"this"document"is "to"describe"

the"process"of"obtaining"permission"to"do"dredging"and"the"concerns"that"are"presented"and"the"assurances"

that"must"be"given"to"obtain"permission.

It"is "hoped"that"this"document"will "illustrate"that"a"balance"needs"to"be"struck" to" saFsfy" all"the"relevant"

needs." The"need" for" commerce" to" thrive" in" the"modern" world," with" the"need" to" preserve" species"and"

acFviFes"for"present"and"future"generaFons"and"the"need"to"live"in"harmony"and"have"respect"for"ourselves"

and"our"surroundings.

Judson"Farray

21st"February"2014



ForewordEvery"Fme"I"start" talking" about"an"environmental"issue,"I"get"the"same"response"from"Judson;"“everyone"

wants "to"have"airUcondiFoning”,"“everyone"wants"to" charge"their" iPod”."It’s"a"metaphor"for"our"need" for"

energy,"specifically"electricity"in"our"everyday"lives."Hence"(to"many"environmentalists’"dismay),"the"fastest"

way"to"do"this "(at"the"moment)"is"to"burn"fossil"fuels."To"get"fuel"to"the"power"plant"we"need"to"transport"it,"

in"this"case"via "the"sea,"and"to"maintain"transportaFon"efficiency"we"must"dredge"navigaFonal"channels."

The"quesFon"posed"is;"“how"do"we"carry"out"dredging"acFviFes"in"a"way"that"causes "minimal"damage"to"

the"surrounding"environment?”."The"term"“environment”"encompasses"not"only"the"tradiFonal"definiFon"

of"the"natural"habitat"and"associated"organisms,"but"also"neighbouring"industrial "faciliFes,"ports,"residenFal"

areas,"fishermen"and"other"marine"traffic.

In"this"report,"Farray"gives "an"overview"of" the"dredging" process," the"equipment"needed," the"regulaFons"

that"govern"it"and"the"possible"impacts."This"is"illustrated"though"a"case"study"of"a"dredging"project"in"a"port"

in"Point"ForFn,"Trinidad."He"clearly" idenFfies "the"issues,"both"theoreFcal"and"those"actually"encountered,"

and"how"these"gaps "can"be"closed."While"there"are"procedures"to"follow,"the"case"study"shows"that"there"

are"sFll"areas"of" uncertainty"when" it" comes"to"planning"and"execuFng" projects." There"is"a"great"need"to"

document"these"issues."I"hope"that"these"points "can"be"used"to"influence"future"decision"making"to"aid"in"

the" streamlining" of" the" whole" process;" from" planning," applying" for" the" CEC," the" physical" process,"

monitoring" and" any" followUup"work."CommunicaFon" is"paramount" so" that"efforts"are"not"duplicated" as"

many"of"the"same"key"players "share"these"operaFons."It"must"also"be"noted"that"these"acFviFes "do"not"take"

place" in"a"vacuum."The"same"neighbours"that"one"aHempts"to"avoid" impacFng"also"carry" out" their" own"

operaFons."CumulaFve"effects"must"be"considered,"especially" in"the"heavy" industrial"areas"of" the"Gulf"of"

Paria."

It" is" important" to" note" that" this" report" does"not" focus"on" the" suitability" of" the" site" as "it" is" an" already"

established"port."However,"for"areas "with"first"Fme"dredging"this "must"be"taken"into"account."Documents"

that" should" be" referenced" include" the" EMA’s " Hydrodynamic" Guidebook" which" outlines " the" need" for"

hydrographic"surveys"as"well"as "parFcular"habitats "and"sensiFve"areas."TradeUoffs"between"the"acFvity"and"

conservaFon" must" be" given" consideraFon." While" this" report" only" focuses" on" an" industrial" dredging"

operaFon,"the"lessons"learnt"can"be"applied"for"other"dredging"projects."For"example;"an"important"issue"in"

the" country" is " the" improvement" of" the" transportaFon" system." Use" of" the" water" taxis " and" ferries" is"

becoming" increasingly"popular"with"the"traveling"public"who"need" to" commute"to"between"the"different"

ends"of" the"country." Issues"have"been"brought"forward"with" the"siFng" of" these"terminals," including" the"

requirement"for"dredging" of" new"channels."There"is"need"for"a"detailed" costUbenefit"analysis"of" locaFon,"

infrastructure"and"impacts"of"the"terminals."

Environmentalists"get"a "lot"of" “heat”"for"tending"to"focus"solely"on"the"environmental"side"of"an"issue,"and"

not"considering" other" benefits" that"may"outweigh" the"need" to"protect" the" natural"environment." It" is "a"

noFceable"flaw"in"human"nature;" dividing" an" issue"into"black"and"white"and"not" taking" into"account" the"



posiFves"of"both"sides."I"hope"that"as"we"move"forward"in"developing"our"naFon"that"we"look"for"a"holisFc"

approach" and" focus" on" sustainable" development." Using" this" concept" we" not" only" aim" to" beHer" our"

economy" and" infrastructure," but" at" the" same" Fme" ensure" that" there" are" resources" len" for" future"

generaFons.

The"twentyUfirst"century"has"brought"an"increased"focus"on"environmentalism;"part"of"this"is"the"promoFon"

of" the"concept"of" sustainable" development."To"many" this" is" a"pipe" dream." To" them," I"say" that" doesn’t"

maHer."Even"if"we"were"to"fall"short;"the"strides"made"in"our"aHempt"would"be"far"beHer"than"if"we"had"not"

tried"at"all."This"is"the"issue"addressed"in"this "report;"how"to"carry"out"industrial "dredging"works,"while"at"

the"same"Fme"looking"at"environmental"impacts"of"dredging."It"highlights "the"issues"that"were"faced"when"

trying"to"set"up"a"project"and"how"to"reconcile"policy,"acFon"and"the"soluFons.

Michele"de"Verteuil

26th"February"2014"



Table(of(Contents

1:(HISTORY(OF(ENVIRONMENTAL(CONCERNS(RELATED(TO(THE(SEA( 1

INTRODUCTION( 1

THE(GULF(OF(PARIA’S(COASTAL(PROFILE( 2

2:(THE(BACKGROUND(OF(THE(MAINTENANCE(DREDGING(PROJECT( 3

THE(NEED(FOR(THE(DREDGING( 3

A(CASE(STUDY( 3

PREVIOUS(CECS( 4

THE(PORT(PRACTITIONER’S(DREDGING(OPTIONS( 4

GEOLOGICAL+FACTORS+OF+THE+DREDGE+AND+DUMP+SITES" 4

AVAILABILITY+OF+CONTRACTORS’+EQUIPMENT" 5

COMPARATIVE+COSTS+OF+VARIOUS+OPTIONS." 5

ASSEMBLING+A+DREDGING+PLAN" 5

DESCRIPTION(OF(THE(PREFERRED(OPTION( 6

3:(ENVIRONMENTAL(ETHOS( 8

INTRODUCTION( 8

ENVIRONMENTALISM(IN(CULTURES( 9

4:(MARINE(AND(COASTAL(ECOLOGY( 10

INTRODUCTION( 10

DESCRIPTION(OF(THE(MARINE(ENVIRONMENT( 11

CHANGES+IN+THE+MARINE+ENVIRONMENT" 12

5:(MARINE(ENVIRONMENTAL(COMPONENTS( 13

INTERTIDAL(ZONE( 13

BENTHIC(ZONE( 13

HABITATS( 13

ECOLOGICAL(RECEPTORS(AND(VALUES( 14

FISHERIES( 14

MARINE(MAMMALS( 14

HYDRODYNAMICS(AND(THE(SEDIMENTARY(REGIME( 15

WATER(COLUMN( 15

TURBIDITY( 15



6:(ENVIRONMENTAL(IMPACT(OF(A(DREDGING(OPERATION( 17

CORPORATE(RESPONSIBILITY( 17

ENVIRONMENTAL(IMPACT(OF(DREDGING(ACTIVITY( 17

DREDGED(SPOIL( 18

DREDGED(SPOIL(CHARACTERISTICS( 19

ASSESSING+POTENTIAL+IMPACT+ON+DISPOSAL+SITES" 19

DISPOSAL(SITE(SELECTION( 20

DISPOSAL+SITE+CHARACTERISTICS" 21

7:(DREDGING(AND(DISPOSAL(SITE(SAMPLING(AND(ANALYSIS( 22

SIDE(SCAN(SONAR( 22

VIDEO(‘SPLASHCAM’(DROPS( 23

BENTHIC(GRAB(SURVEY( 24

PHYSICAL(IMPACT(OF(DREDGED(SPOIL(DISPOSAL( 24

MANAGING+THE+PHYSICAL+EFFECTS+OF+DREDGED+SPOIL+DISPOSAL " 25

DISPOSAL+SITE+DISPERSAL+CHARACTERISTICS" 26

IMPACT(HYPOTHESIS( 26

RECOMMENDATIONS(FOR(MONITORING(THE(DISPOSAL(SITE( 27

8:(CERTIFICATE(OF(ENVIRONMENTAL(CLEARANCE( 28

MAINTENANCE(DREDGING(SEDIMENT(RETENTION( 28

HYDROCARBON]CONTAMINATED(RUN]OFF( 30

NOISE(AND(VIBRATION( 31

SEWAGE( 31

WASTE(MATRIX( 32

9:(CONCLUSIONS( 36

APPENDICES( 37

A.1(TYPES(OF(DREDGING( 37

A.1.1+CAPITAL+DREDGING " 37

A.1.2+PREPARATORY+DREDGING" 37

A.1.3+MAINTENANCE+DREDGING" 37

A.1.4+LAND+RECLAMATION" 37

A.1.5+BEACH+NOURISHMENT" 37

A.1.6+HARVESTING+MATERIALS" 37

A.1.7+SEABED+MINING" 37



A.1.8+CONSTRUCTION+MATERIALS" 38

A.1.9+ANTIUEUTROPHICATION" 38

A.1.10+CONTAMINANT+REMEDIATION" 38

A.1.11+REMOVING+TRASH+AND+DEBRIS" 38

A.2(TYPES(OF(DREDGING(VESSELS( 38

A.2.1+GRAB+DREDGER" 38

A.2.2+TRAILING+SUCTION+HOPPER+DREDGER" 38

A.2.3+SUCTION+DREDGER" 39

A.2.4+CUTTER+SUCTION+DREDGER" 39

A.2.5+AUGER+SUCTION" 39

A.2.6+JET+LIFT" 39

A.2.7+AIR+LIFT" 39

A.2.8+BUCKET+DREDGING" 39

A.2.9+BACKHOE/DIPPER" 40

A.2.10+WATER+INJECTION" 40

A.2.11+PNEUMATIC" 40

A.2.12+BED+LEVELER" 40

A.2.13+AMPHIBIOUS" 40

A.2.14+SUBMERSIBLE" 40

READING(LIST( 41



1:(History(of(environmental(concerns(related(to(the(sea

Introduc5on

As"shipyards"started" launching" ‘larger’" oil" tankers"post"World"War" II,"coastal" naFons"became"concerned"

with"protecFng"the"marine"environment."These"concerns"led"to"OILPOL"being"adopted"in"1958."OILPOL"was"

designed"to" prevent"marine"polluFon" caused"by" rouFne" tanker" operaFons," including" tank" cleaning" and"

discharges"of"oily"ballast"water."However,"major"spills"of"cargo"oil"resulFng"from"grounding"accidents"were"

beyond" its" scope."Meanwhile," tankers" have"been"built" larger,"and" the" transportaFon" needs"of" harmful"

substances"other"than"oil"have"increased."Then"IMCO,"the"predecessor"of" IMO"worked"on"the"InternaFonal"

ConvenFon"for"the"PrevenFon"of"PolluFon"from"Ships,"finally"adopted"in"1978"as"MARPOL."This"ConvenFon"

includes "not" only"heavy" oil,"which"was"covered"by"OILPOL," but"also" all"other"kinds"of" oil,"harmful" liquid"

substances,"and"sewage"water,"so"as"to"prevent"marine"polluFon"in"a"wider"sense.

The"need"for"the"prevenFon"of"contaminaFon"is "well"covered"in"history,"going"back"to"lepers"in"the"bible"

through"Thyphoid"Mary"and"the"anthrax"laden"anermath"of"9/11"up"to"present"day."In"Europe,"convenFons"

on"the"prevenFon"of"contaminaFon"have"been"held"since"the"1850s."

The" focus" has"historically" been" on" the"diseases" that" affect"humans"and"animals." The" inclusion" of" plant"

quaranFne"divisions"in"State"agencies"came"in"the"early"1900s."

Around"1903"there"was"a"recorded"mass"occurrence"of"a "species"of"Asian"algae"in"the"North"Sea."It"was"not"

unFl"the"1970s "that"scienFsts"started"to"recognise"the"phenomenon"and"effects"of"AquaFc"Invasive"Species."

Through"the"1990s,"the"IMO"adopted"various"guidelines"and"resoluFons "on"the"subject"which"culminated"in"

the" InternaFonal"ConvenFon" for" the"Control" and"Management"of" Ships’"Ballast"Water" and"Sediments"in"

2004.

In"1972"the"UN"Conference"on"the"Human"Environment"in"Sweden"created"the"United"NaFons"Environment"

Programme." Its " task" was " to" oversee" all" maHers" dealing" with" the" environment" addressed" by" the"

UN." Among"its "responsibiliFes"and"successes"is"the"Regional"Seas "Programme." The" Programme"

has"thirteen"agreements"covering"over"140"countries."The"two"most"successful"of"the"thirteen"convenFons"

are"the"Barcelona"ConvenFon,"dealing"with"the"Mediterranean"Sea"and"the"Cartagena"ConvenFon,"dealing"

with"the"Caribbean."Cartagena"along"with"its "three"protocols,"dealing"with"oil"spills,"protected"areas,"and"

landUbased" polluFon," respecFvely," is" one" of" the" most" comprehensive" Regional" Seas" Programmes." In"

addiFon,"in"2002,"Cartagena"was"also"coordinated"with"the"Intergovernmental"Oceanographic"Commission"

for"the"Caribbean"of"UNESCO"by"way"of"a"Memorandum"of"CooperaFon."Cartagena" is" not" a" standalone"

agreement" or" designed" to" supersede" existent" agreements." Partly," it" is" designed" to" supplement" other"

mulFlateral" treaFes" in" place" such" as"MARPOL"73/78"and" the"ConvenFon" on" Biological"Diversity" and" to"

complement"UNCLOS."

Despite"all"of" the"ConvenFons"to"which"country"might"be"a "signatory,"someFmes"the"reality"of"pusng" the"

provisions" into" acFon" can" be" hampered" by" lack" of" experience," lack" of" training," lack" of" interest" and"

bureaucracy.



The"relaFvely"large"number"of"agencies"that"are"involved"in"obtaining"permission"to"dredge"in"Trinidad"and"

Tobago" and" the"scarcity" of" commercial"marine"experFse" in"many"of" those"agencies"mean" that"the"port"

pracFFoner"has"to"become"the"subject"maHer"expert.

The"port"pracFFoner"has"to"be"able"to"answer"any"quesFons"by"the"people"who"control"the"port’s "purse"

strings," the" Environmental" Management" Authority" and" the" various " government" authoriFes." The" port"

pracFFoner" will" also" be" expected" to" evaluate" and" recommend" service" providers" from" the" available"

dredging" and" hydrographical" surveying" services" and" equipment" and" advise" the" port’s" procurement"

department"on"negoFaFons"with"the"suppliers.

The(Gulf(of(Paria’s(coastal(profile

Trinidad" and"Tobago" conforms"with" the"world’s "usage" of" coastal" zones"on" one"coast."Coastal"zones"are"

dynamic"areas"of" natural"change"and"of" increasing"human"use."They"occupy" less"than"15%"of" the"earth's"

land"surface;" yet"accommodate"more"than" 50%" of" the"world" populaFon" (it" is"esFmated"that" 3.1" billion"

people"live"within"200"kilometres"from"the"sea)."With"threeUquarters"of" the"world"populaFon"expected"to"

reside"in"the"coastal"zone"by"2025,"human"acFviFes"originaFng" from"this"small"land"area"will"impose"an"

inordinate"amount" of" pressures "on" the"global" system."Coastal" zones" contain" rich" resources" to" produce"

goods"and"services"and"are"home"to"most"commercial"and"industrial"acFviFes.""

In"Trinidad"and"Tobago,"more"than"half"of"the"populaFon"now"lives"along"the"west"coast"of"the"larger"island"

and"coastal"zone"resources"produce"much"of" the"naFon’s"economic"wealth."Eight"of" the"country’s"eleven"

ports"are"located"on"the"west"coast."The"natural"gas,"extracted"off"the"north"and"east"coasts,"is"transferred"

by"pipeline"to"faciliFes"on"the"centralUwest"and"southUwest"coasts"for"processing"and"exportaFon.""

In"addiFon,"the"fishing,"shipping"and"tourism"industries"all"compete"for"vital"space"along"the"coastline"that"

contains"some"of" fragile"and"valuable"natural"habitats."SoluFons"for"both"industrial"and"protected"zones"on"

this"short"coast"is"difficult"but"doable."

Trinidad"and"Tobago"is"located"at"the"southern"end"of"the"eastern"Caribbean"island"chain"on"the"conFnental"

shelf" off" northeast"South" America," some" 8"miles "east" of" Venezuela," the" islands" lie" downstream"of" the"

ouvlow"of" 17"South"American" rivers,"including" the"Amazon"and"Orinoco,"and"at"the"confluence"of"major"

ocean" currents " such" as " the" North" Equatorial" current." This" ouvlow" has" led" to" highly" diverse" marine"

environment.



2:(The(background(of(the(maintenance(dredging(project((

The(need(for(the(dredging

When" the" dredging" is" to" return" the" navigaFonal" channel" to" its" design" dimensions," it" is "maintenance"

dredging."It"is"important"to"note"immediately"that"the"previous"depth"and"width"being"applied"for"must"be"

proved" through" documentaFon." In" these" cases," no" Environmental" Impact"Assessment" (EIA)" is" normally"

required"and" if" a"CerFficate"of" Environmental"Clearance"(CEC)" has"been"previously"and" recently" granted,"

reapplicaFon"for"a"CEC"may"not"be"required"but"in"all"cases"the"EMA"must"be"advised"of"the"port’s"desire,"

intenFon"and"reason"for"dredging.

If" the"dredging" is "to"facilitate"an" expansion"of" the"navigaFon"of" the"navigaFonal" channel" and"or" turning"

basin,"an"EIA"will" likely" be"required."Guidance"on"EIA" is "available"on" the" EMA’s"website"and" engaging" a"

consultant"is"recommended"prior"to"applicaFon.

A(Case(Study

Figure"2:"LNG"Terminal"at"Point"ForFn"with"second"jeHy"under"construcFon."The"13"metre"deep"navigaFon"

channel"was"dredged"to"be"600"metres"wide"from"the"original"200"metres"wide"to"accommodate"the"

second"jeHy.

At" the" EMA" library," the"course"of" the"development"of" the" LNG"terminal"at"Point" ForFn"can" be"charted."

Taking"up"the"story"at"the"capital"dredging" in"2004"which"involved"widening" the"channel"from"200"metres"

wide"to"600"metres "wide"and" the"turning" basin"to"accommodate"the"construcFon"of" a"second" jeHy"and"

improve"navigaFonal"safety"

In"2009," the"areas"by" the"berth"parFcularly"by"way"of" the"jeHy" fenders "had"silted"up"and"ships"alongside"

were"exposed"to"the"possibility"of"having"less"than"minimum"under"keel "clearance"" if"they"finished"loading"

around" low"water."The"corners"of" the" turning"basin"also" silted"up"and" the"channel"markers"were"moved"

inward"to"compensate."There"had"been"challenges"obtaining"a"CerFficate"of"Environmental"Clearance"due"

to"disputes "over"the"locaFon"of" the"disposal"site." The"port"was"allowed"to"relocate"dredged" spoil"to" the"

deeper"areas"with"the"channel"unFl"the"disposal"site"issue"was"resolved.



Previous(CECs

The"files"of"all"applicaFons"made"to"the"EMA"are"available"to"the"public"at"the"EMA"library"in"Port"of"Spain."

These"are"a "useful"but" limited"source"of" informaFon"about"CEC" applicaFon."While"the"files "are"available"

individually,"there"is "no"database"that"allows"trends"to"be"easily"idenFfied."Some"trends"were"idenFfied"in"

‘Guidelines "for"Maintenance"Dredging"in"Trinidad"and"Tobago’"(GMDTT),"published"by"Spree"Spirit"(2014)."A"

significant"finding"was"that,"in"the"10"years"prior"to"2013,"EMA"asked"applicants "for"‘further"informaFon"in"

70%"of"applicaFons."GMDTT"has"a"summary"of"the"further"informaFon"requested.

The(Port(Prac55oner’s(Dredging(Op5ons

While" port" closure" is " not" an" opFon" and" especially" not" for" ports " through" which" a" country" earns" the"

significant"porFons"of" its "Gross "NaFonal"Product."The"dredging"brings"together"numerous"stakeholders"and"

suppliers," involves" risks"associated"with" heavy" moving" machinery" and" is "also" a"major" expenditure"item."

CommunicaFon," safety" leadership" and" monitoring" to" get" value" for" money" are" the" keys" to" successful"

dredging"operaFons.

Geological)factors)of)the)dredge)and)dump)sites

The"Port"PracFFoner"should"already"be"aware"of"the"geological"nature"of"the"seabed"in"around"the"port"

from"the"Admiralty"charts"for"the"area."This"would"cover"whether"it"was"mud,"sand,"shell,"shingle,"rock"etc."

The"chart"will"also"indicate"whether"any"known"wrecks"or"oil"wells"are"in"the"area"to"be"dredged."The"Port"

PracFFoner"must"also"make"himself"aware"of"the"vegetaFon"and"associated"marine"life"in"the"area"for"

which"he"is"responsible."

AddiFonal"to"that,"the"Port"PracFFoner"must"be"open"to"the"possibility"that"a"significant"amount"of"

‘foreign’"manmade"maHer"and"objects"could"be"present"on"his"seabed."These"foreign"items"may"or"may"not"

have"varying"effects"on"the"environment"but"could"affect"the"dredging"equipment"and"therefore"the"choice"

of"dredging"equipment"hired."""

Figure"3:"Clamshell"dredger"about"to"grab"some"silt"from"the"seabed.



Availability)of)contractors’)equipment

Mobilising"dredging"equipment"from"the"United"States"or"Europe"is"very"expensive."There"aren’t"many"

dredgers"based"in"Trinidad"and"Tobago."The"dredging"equipment"in"the"Caribbean"region"serves"all"of"the"

ports"in"the"region,"including"the"approaches"to"the"Panama"Canal."In"2013,"the"expansion"of"the"Panama"

Canal"is"in"progress"and"uFlising"more"that"normal"amount"of"dredging"equipment."As"a"result"of"the"

scarcity"of"equipment,"it"is"equipment"availability"that"usually"decides"when"the"dredging"will"take"place."

The"Port"PracFFoner"has"to"engage"the"services"of"the"type"of"dredger"or"types"of"dredgers"appropriate"to"

the"nature"of"the"material"or"materials"to"be"dredged,"appropriate"to:"the"iniFal"and"required"depths,"the"

volume"of"material"to"be"dredged"and"appropriate"to"the"physical"layout"of"the"approaches,"channel,"port"

and"berths."

The"Port"PracFFoner"must"be"able"to"assist"the"port"with"the"idenFficaFon"and"selecFon"of"the"source"of"

the"equipment"to"be"used"for"the"safe,"effecFve"and"efficient"implementaFon"of"the"dredging"plan"then"

occurs."

Compara;ve)costs)of)various)op;ons.

The"Port"PracFFoner"has"to"prepare"and"present"the"dredging"plan"budget"in"accordance"with"the"

organisaFon's"requirements."This"preparaFon"can"be"years"before"the"dredging"operaFon."The"Port"

PracFFoner"has"to"engage"the"services"of"a"hydrographic"surveyor"to"establish"the"volume"that"is"to"be"

dredged."This"volume"is"a"key"input"to"the"scope"of"work"for"the"dredging"project,"bearing"in"mind"that"

dredging"contractors"normally"charge"by"volume"but"the"rate"per"cubic"metre"includes"consideraFons"for"

the"duraFon"expected."

The"Port"PracFFoner"has"to"be"aware"of"the"differences"in"the"rates"for"the"hire"of"different"types"of"

dredging"equipment."ConsideraFon"must"also"be"given"to"ancillary"expenses"associated"with"the"dredging."

A"Port"PracFFoner"trying"to"manage"the"expectaFons"of"his"(or"her)"principals"would"factor"in"the"cost"to"

the"port"of"any"shipping"delays"caused"by"the"dredging"and"the"cost"of"interrupFng"the"dredging"for"the"

passage"of"shipping.

The"Port"PracFFoner"has"to"check"the"shipping"projecFons"and"planned"maintenance"schedule"of"the"

busier"berths"to"try"and"make"use"of"‘natural’"windows"in"ship"movements."There"may"be"seasonal"

fluctuaFons"in"the"volume"of"shipping"passing"through"the"port."These"should"also"be"taken"into"account"

when"Fming"the"dredging"operaFon."Trying"to"dredge"around"a"busy"shipping"schedule"will"slow"the"

dredging"and"or"almost"inevitably"cause"delays"to"ships,"possibly"incurring"demurrage"charges.

Assembling)a)Dredging)Plan

The"port"will,"very"likely"operate"a "Control"of"Work"policy"which"will "include"as"a"minimum:"a"documented"

procedure," a"risk" assessment"and"a "permit" to"work" for" the"operaFon."The"documented" risk" assessment"

should"detail" the"hazards"and"miFgaFons"for"every" acFvity" related" to"the"dredging:" from"the"transfer"of"

personnel"to"and"from"the"dredger"to"the"disposal"of"spoil,"which"might"be"occurring"outside"port"limits."In"



order"to"provide"safety"leadership"and"to"provide"accurate"records,"the"port"might"take"the"opFon"to"place"

a"person"or"persons"on"board"the"dredger"as"client"representaFves."It"will"be"the"responsibility"of" the"Port"

PracFFoner" to" idenFfy" and" arrange" any" training" required" for" personnel" involved" in" the" planning" and"

performance"of"the"dredging."

A"dredging"plan’s"parameters"may"include:"legislaFve"requirements,"development"consent"requirements,"

operaFng"hours"limitaFons,"extracFon"volume"limitaFons,"finished"surface"and"subUsurface"level"

requirements,"dredging"and"disposal"machinery"capacity,"catering"for"the"rock,"sand"or"gravel"

characterisFcs,"maximum"dredging"depth,"catering"for"Fdal"or"current"condiFons,"maximum"and"minimum"

slurry"delivery"distances,"this"depends"on"bed"condiFon"and"dredger"type,"reporFng"and"record"

requirements"and"procedures"and"underwater"obstacles.

Armed"with"that"basic"informaFon,"the"Port"PracFFoner"must"interpret"and"clarify"the"parameters"relevant"

to"the"planning"and"implementaFon"of"the"dredging"operaFons."The"Port"PracFFoner"will"issue"and"explain"

the"dredging"plan"to"port"management,"team"members"and"others"involved,"for"the"safe,"effecFve"and"

efficient"implementaFon"of"the"plan."Then"the"wait"for"the"various"permissions"begins.

Descrip5on(of(the(Preferred(Op5on

With"the"contractors"selected,"the"CEC"granted"and"the"dredging"plan"approved,"the"Port"PracFFoner"must"

ensure" that" dredging"operaFons"begin"as"scheduled" and"provide"Fmely" onUgoing" support"and"advice"to"

those"implemenFng"the"dredging"plan."The"Port"PracFFoner"through"his"team"will"ensure"that"the"dredge"

area "is "correctly"marked"out"in"accordance"with"the"dredging"plan."PracFcally"this"will"include"moving" the"

navigaFon"channel"markers"(if" required)" and"removing" current"meter"equipment"(if" required)"out"of" the"

way"of"the"dredger."The"Port"PracFFoner’s"team"must"ensure"that"records"and"reports"are"maintained"and"

issued"in"accordance"with"the"dredging"plan"and"other"relevant"legislaFve"and"organisaFonal"requirements."

The" team"must"also"monitor" the"dredging" plan"performance"against"dredge"operaFons"parameters," the"

budget"and"relevant"legislaFve"and"organisaFonal"requirements."This "monitoring"must"include"checking"on"

over" dredging," the" dredger" is" paid" by" volume" removed" and" will," understandably," not" try" to" limit" the"

revenue" it" earns." The" Port" PracFFoner" must" be" ready" to" resolve" anomalies" in" consultaFon" with" the"

dredging"contractor’s"project"manager"and"other"relevant"stakeholders"(if"required)"and"issue"appropriate"

instrucFons"for"adjustments"to"the"plan"and/or"its"implementaFon"unFl"successful "compleFon."The"seabed"

in"most"of"the"Gulf"of"Paria"is"mud"and"silt."Ports "in"Trinidad"and"Tobago"usually"engage"the"services"of"an"

internaFonally" renowned"dredging" companies"which"would"source"an"appropriate"trailing"sucFon"hopper"

dredger" (TSHD)" out" of" its" fleet," based" on" locaFon" and" commitments." The" TSHD" is" used" for" ‘bulk’" silt""

removal"in"the"channel"and"turning"basin.



Figure"4:"SchemaFc"of"Trailing"SucFon"Hopper"Dredger

The"grab"crane"barge"dredger"is"usually"used"along"the"area"of"berth"lines "and"around"the"perimeter"of"the"

channel"and"turning"basin."

Figure"5:"Clamshell"dredger"‘Elisa’"dropping"a"bucket"load"of"silt"into"the"hopper"barge



3:(Environmental(Ethos

Introduc5on

There" are" scienFfic" and" social" reasons" for" compleFng" Environmental" Impact" Assessments." There" are"

numerous"examples"of"marine"organisms"being"transported"in"ballast"water."San"Francisco"Bay"is "one"the"

most"heavily" ‘invaded’"estuaries "in"the"world"with"over" eighty" five"species"having"been" introduced"there"

(source:#Mark#Prado,#Marin#Independent#Journal,#February#2008)."Economic"costs"from"invasive"species"can"

be"separated"into"direct"costs"through"producFon"loss"in"agriculture"and"forestry,"and"management"costs"

of" invasive"species."EsFmated"damage"and" control"cost" of" invasive"species" in" the"U.S." alone" amount" to"

more"than"$138"billion"annually"(source:#U.S.#Fish#and#Wildlife#brochure,#January#2012)."In"addiFon"to"these"

costs,"economic"losses"can" occur" through" loss"of" recreaFonal" and" tourism" revenues." Economic"costs"of"

invasions,"when"calculated"as "producFon"loss"and"management"costs,"are"low"because"they"do"not"usually"

consider"environmental"damages."If"monetary"values"could"be"assigned"to"the"exFncFon"of"species,"loss"in"

biodiversity,"and" loss"of" ecosystem"services,"costs"from"impacts"of" invasive"species"would"be"significantly"

higher"(source:#Costanza#et#al.,#1997).

Invasive"species" can"have" impacts"on" recreaFonal"acFviFes"such" as"fishing" and" waterUbased"recreaFon."

They"negaFvely"affect"a"wide"array"of"environmental"aHributes"that"are"important"to"support" recreaFon,"

including" but"not" limited" to" water" quality," plant" and" animal" quanFty," diversity" and" species" abundance"

(source:#hJp://www.fws.gov/home/feature/2012/pdfs/costofinvasivesfactsheet.pdf).

There"can"be"economic"benefits"from"some"‘invasive’"species"and"these"are"usually"underUreported."Asian"

oysters," for"example,"are"beHer"at"filtering"out"water"pollutants"than"North"American"oysters."The"Asian"

oysters"also"grow"faster"and"withstand"disease"beHer"than"the"North"Americans."Biologists"are"considering"

releasing"the"mollusk"in"the"Chesapeake"Bay"to"help"restore"oyster"stocks"and"clean"up"the"bay’s "polluFon."

A" recent" study" by" the" Johns"Hopkins"School"of" Public" Health" found" the"Asian" oyster" could"significantly"

benefit" the" bay’s" deterioraFng" water" quality" (source:# hJp://www.jhsph.edu/news/newsQreleases/2006/

graczykQoyster.html).

For"many"invasive"species"there"are"exisFng"or"potenFal"commercial"benefits."For"instance,"Silver"Carp"and"

Common"Carp"(where"heavy"metals"are"not"excessive"in"their"flesh)" can"be"harvested"for"human"food"and"

exported"to"markets"already" familiar"with"the"product"or" into"pet" foods"(source:#hJp://en.wikipedia.org/

wiki/Asian_carp)."Numerous"vegetaFve"'invasives'" like"water"hyacinth,"when" in"sufficient"quanFFes"to"be"

harvestable," can" be" turned" into" methane" digesters" if" no" other" beHer" use" can" be" determined." Some"

interesFng"data"on"organisms"digesFng"methane"is"being"uncovered"in"the"anermath"of"the"Macondo"Well"

rupture"in" the"Gulf"of"Mexico"(source:# Jyllian#Kemsley,#AVer#the#Deepwater#Horizon#Disaster,# Chemical#&#

Engineering#News,#2013).



http://www.fws.gov/home/feature/2012/pdfs/costofinvasivesfactsheet.pdf

http://www.fws.gov/home/feature/2012/pdfs/costofinvasivesfactsheet.pdf

http://www.jhsph.edu/news/news-releases/2006/graczyk-oyster.html




http://en.wikipedia.org/wiki/Asian_carp




Environmentalism(in(cultures

Although"Animism"has"now"been"replaced"by"the"current"great"world"religions,"it"is"likely"that"the"feeling"of"

powerlessness"before"the"forces"of"nature"led"to"early" forms"of" religion."So"the"fervour"with"which"some"

people"in"the"developed"world"pursue"environmental"issues"is,"in"a"strange"way,"a"return"to"earlier"beliefs.

In"the"developed"world," some"consider" that"with"the"perceived" decline"of" organised"ChrisFanity," recent"

disenchantment" with" capitalism’s" greedy" banksters" and" the" discrediFng" of" Marxism," environmentalism"

seems"to"have"filled"a"void"for"many."

In" the" developing" world" the" balance" is" different" with" regard" to" religion," for" the" Fme" being" at" least."

Environmental" Science" courses" at" universiFes" are" offered" and" reasonably" subscribed" and" the" first"

significant"evidence"of"ecoUwarriors,"are"visible.

Environmentalism" is " defined," in" the" American" Heritage" dicFonary" as" ‘advocacy" for" or" work" toward"

protecFng"the"natural"environment"from"destrucFon"or"polluFon’.

Environmentalists," in" the"developed"world," believe"that" people," in" the"developed"world," seem" to" have"

disconnected"themselves"from"nature"and"are"struggling"to"find"the"value"of"nature."They"see"nature"as"the"

source" of"much" value," spiritually," culturally," healthUwise"or" economically." The"environmentalists"see" the"

lack" of" valuaFon" as" an" underlying" cause" for" the" observed" degradaFon" of" ecosystems" and" the" loss" of"

biodiversity.

MarFn"Livermore,"who"is"an"independent"consultant"with"a"background"in"industry,"stated:"

“All"species"affect"their"environment"to"a"greater"or"lesser"degree."Termites"build"complex"homes,"beavers"

construct" dams" to" alter" the"flow" of" streams" and" grazing" animals"profoundly" alter" the"balance" of" plant"

species."People"do"the"same."The"difference"is"that"we"have"a"uniquely"greater"capacity" to"do"so."As "this"

capacity"has "grown,"so"has"our"awareness"of" the"consequences,"and"our" ability" to"make"raFonal"choices"

between"opFons”"(source:#hJp://news.bbc.co.uk/2/hi/science/nature/4766096.stm,#2006).

In"the" last"generaFon,"environmental"quality" in" the"developed"world"has"improved"greatly"by"almost"any"

measure."In"the"developing"world" that"change"is"slower"and,"so" far,"has"to"be"driven"by"people"from"the"

developed"world."With"the"speed"and"effecFveness "of" Internet"communicaFon,"the"current"situaFon"will"

not"remain"for"much"longer."And"companies"like"AtlanFc"LNG,"with"shareholders "like"Shell,"BG"and"BP"are"

mindful"that"the"plant"might"be" in" the"developing" world"but" the"customers"are"mainly" in" the"developed"

world.



http://news.bbc.co.uk/2/hi/science/nature/4766096.stm

http://news.bbc.co.uk/2/hi/science/nature/4766096.stm

4:(Marine(and(Coastal(Ecology

Introduc5on

Marine"ecosystems"cover"approximately"71%"of"the"Earth's"surface"and"contain"approximately"97%"of" the"

planet's"water"(source:#hJp://www.noaa.gov/ocean.html)."They"generate"32%"of"the"world's"net"primary"

producFon."They"are"disFnguished"from"freshwater"ecosystems"by"the"presence"of"dissolved"compounds,"

especially"salts," in"the"water."Approximately" 85%"of" the"dissolved"materials" in"seawater"are"sodium"and"

chlorine"(source:# hJp://en.wikipedia.org/wiki/Aqua_c_ecosystem)."Seawater"has"an"average"salinity"of"35"

parts "per"thousand"(ppt)"of"water."Actual"salinity"varies"among"different"marine"ecosystems"(source:#hJp://

en.wikipedia.org/wiki/Seawater)."

Marine"ecosystems"can"be" divided" into" the"following" zones:" interFdal "(the" area" between"high" and" low"

Fdes),"neriFc"zone"(the"relaFvely" shallow"part"of" the"ocean"that"lies"over" the"conFnental"shelf);"oceanic"

(open"water);"abyssal"and"hadal"(deep"water"and"trenches),"benthic"(boHom"substrates)."Different"habitats"

include"estuaries,"salt"marshes,"coral"reefs"and"hydrothermal"vents"(where"chemosyntheFc"sulfur"bacteria"

form"the"food"base)."

Figure"6:"Zones"in"the"marine"ecosystem.

Classes"of" organisms"found"in"marine"ecosystems"include"brown"algae,"dinoflagellates,"corals "(Anthozoa),"

cephalopods,"echinoderms,"and"sharks"(Chondrichthyes)."Fish"caught"in"marine"ecosystems"are"the"biggest"

source"of"commercial"foods"obtained"from"wild"populaFons.

The"coastal"zone"is "a"dynamic"area"of" natural"change"and"of" increasing"human"use."They"occupy"less "than"

15%"of"the"earth's "land"surface;"yet"accommodate"more"than"50%"of" the"world"populaFon"(it"is"esFmated"



http://www.noaa.gov/ocean.html

http://www.noaa.gov/ocean.html

http://en.wikipedia.org/wiki/Aquatic_ecosystem

http://en.wikipedia.org/wiki/Aquatic_ecosystem

http://en.wikipedia.org/wiki/Seawater




that" 3.1" billion" people" live" within" 200" kilometres" from" the" sea)" (hJp://www.savethesea.org/STS

%20ocean_facts.htm)."With"threeUquarters"of"the"world"populaFon"expected"to"reside"in"the"coastal"zone"

b y" 2 0 2 5" ( s o u r c e :# h J p : / / w w w . p r b . o r g / P u b l i c a _ o n s / R e p o r t s / 2 0 0 3 /

RippleEffectsPopula_onandCoastalRegions.aspx)","human"acFviFes"originaFng"from"this "small"land"area"will"

impose"an"inordinate"amount"of"pressure"on"the"global"ecosystem."Coastal"zones"contain"rich"resources"to"

produce"goods"and" services"and"are"home"to"most"commercial"and"industrial"acFviFes." " In"Trinidad"and"

Tobago,"more"than"half"of" the"populaFon"now"lives"along"the"west"coast"of" the"larger"island"(Trinidad)"and"

coastal"zone"resources"produce"much"of"the"naFon’s"economic"wealth."The"fishing,"shipping"and"tourism"

industries"all"compete"for"vital"space"along"the"coastline"that"contains"some"of"fragile"and"valuable"natural"

habitats.

Trinidad"and"Tobago"is"located"at"the"southern"end"of"the"eastern"Caribbean"island"chain"on"the"conFnental"

shelf" off" northeast" South" America," some" 8"miles" east" of" Venezuela;" the" islands" lie" downstream" of" the"

ouvlow"of" 17"South"American" rivers,"including" the"Amazon"and"Orinoco,"and"at"the"confluence"of"major"

ocean" currents " such" as " the" North" Equatorial" current." This" ouvlow" has" led" to" highly" diverse" marine"

environment.

Descrip5on(of(the(Marine(Environment

Trinidad"and"Tobago"has"one"of"the"largest"natural"sheltered"harbours"in"the"world,"the"Gulf"of"Paria,"which"

is "located"south"of" the"hurricane"belt."The"numerous"yachts"that"arrive"at"Chaguaramas"Bay,"in"the"north"

west"corner"peninsular"of"the"larger"island"aHest"to"this."Several"large"ships"are"always"seen"in"the"Gulf"of"

Paria.

The"country’s"economy"is "strongly"influenced"by"the"petroleum"industry."Tourism"and"manufacturing" are"

also" important" to" the" local" economy." Tourism" is" a " growing" sector," although" not" proporFonately" as"

important"as"in"many"other"Caribbean"islands."Growth"has"been"fueled"by"investments"in"liquefied"natural"

gas"(LNG),"petrochemicals,"and"steel."

Trinidad"and"Tobago"is"the"leading"Caribbean"producer"of"oil"and"gas,"and"its"economy"is "heavily"dependent"

upon" these"resources "but" it" also" supplies"manufactured"goods,"notably" food"and"beverages,"as"well" as"

cement"to"the"Caribbean"region."Oil"and"gas "account"for"about"40%"of"GDP"and"80%"of"exports."More"than"

95%"of"these"oil"and"gas"vessel"movements"pass "through"the"Gulf"of"Paria."The""LNG"terminal"has"over"200"

vessel"calls"per"year.

The"port"of"Port"of" Spain"handles"1000"containers"per"day,"half"of"which"are"for"transshipment."While"the"

Port" of" Point" Lisas"is "the"second"major"port" in" Trinidad" and" covers"a" total"area"of" approximately" 19.51"

hectares." With" its" strategic" locaFon," the" port" is" onen" referred" to" as" the" "Gateways" to" the"Americas""

catering"for"containerized"cargo"from"the"U.S.,"Europe,"United"Kingdom"and"the"Far"East."Port"Point"Lisas"is"

a"mulFpurpose" cargo" facility" operaFng" on" a" 24/7" basis " and" the" port" handles" a "wide" range" of" traffic"

including"dry"and"liquid"bulks,"containers,"general"cargo"and"breakUbulk"servicing"both



http://www.savethesea.org/STS%20ocean_facts.htm




http://www.prb.org/Publications/Reports/2003/RippleEffectsPopulationandCoastalRegions.aspx




The"port"of"PointeUaUPierre,"which"serves"the"Petrotrin"Refinery"that"is"incidentally,"the"only"refinery"in"the"

world"to"coUexist"with"a"wildlife"park"is"also"in"the"Gulf"of"Paria."The"refinery’s"capacity"is"175,000"BOPD"and"

is "the"sole"refinery"in"Trinidad"and"Tobago."It"complements"its"crude"oil"producFon"with"purchases "from"the"

smaller"producers,"and"imports"more"than"half"of" its"requirement"from"Venezuela."Seventy"percent"of" the"

refined"products"are"exported"(source:#Emma#Brossard,#PetroCaribe:#Chavez’s# Impossible#Energy#Program,#

Petroleumworld,#2006).

In"addiFon"to"these"major"ports"there"is "a"small"cement"port"at"Claxton"Bay"and"a"fledgling"port"serving"an"

industrial"estate"sFll"in"infancy"at"La"Brea.

Changes)in)the)Marine)Environment)

The"beaches"more"frequented"by"tourists"coming"to"Trinidad"and"Tobago"are"located"on"the"smaller"island"

of"Tobago."The"beach"resorts "on"the"larger"island"are"on"the"north"and"east"coasts."While"the"offshore"oil"

and"gas"plavorms"are"off" these"coasts," their"normal"operaFons"do"not" affect"the"quality" of" the"beaches"

except"to"interfere"with"the"view.

The"issue"of"beaches"and"environment"in"Trinidad"and"Tobago"is"a "sensiFve"one."NaFonals"will"remember"

Clinon"Hill "Beach"in"Point"ForFn,"backed"by"almond"trees,"this"beach"was"a"favourite"of"those"on"Sunday"

excursions." Unfortunately" the" laying" of" the" pipeline" to" provide" gas" for" the" LNG" plant" resulted" in" the"

destrucFon"of"the"beach."Today"there"is"a"large"sea "wall"where"previously"children"played"on"the"sand."For"

bathing"in"this "area,"one"now"has"to"go"to"the"east"of"the"original"beach."A"road"has "been"constructed"close"

to"the"rock"sea"wall"that"parallels"the"seashore"and"runs"along" the"edge"of"the"former"golf" course."From"

along"this"road"one"can"access"the"beach"for"bathing"and"fishing."At"the"end"of"the"road"a"beach"facility"has"

been"built"with"a"large"paved"car"park,"thatched"roofed"picnic"tables,"a "lifeguard"staFon,"changing" rooms"

and"toilets."



5:(Marine(Environmental(Components

Inter5dal(zone

The"interFdal"zone"is"the"area"between"the"high"Fde"and"low"Fde"marks"on"the"shore."It"is "the"area"that"is"

exposed"to"the"air"at"low"water"and"underwater"at"high"water."The"Fdal"range"in"Point"ForFn"is"about"1.2"

metres"and"because"the"port"is"built"on"reclaimed"land," the"area"has "a"correspondingly"narrow" interFdal"

zone." The" different" types " of" marine" life" and" vegetaFon" in" the" interFdal" zone" have" to" adapt" to" an"

environment" of" harsh" extreme." In" the"tropics," the"organisms" can"be" submerged" in" salt"water" for" hours"

every"day"and"every"night,"can"expect"to"be"rained"on"by"fresh"water"at"anyFme"during"the"exposed"period"

and"can"be"baked"in"sun"and"end"up"high"and"dry"and"caked"in"dry"salt."With"the"right"kind"of"wave"acFon"

and"Fme"of"day"organisms"can"experience"all"the"condiFons"in"a"six"hour"period.

Benthic(Zone

The"benthic"zone"is"the"ecological"region"at"the"lowest"level"of"a"body"of"water"such"as"an"ocean"or"a"lake,"

including" the" sediment" surface" and" some" subUsurface" layers." Organisms" living" in" this " zone" are" called"

benthos."They"generally"live"in"close"relaFonship"with"the"substrate"boHom;

Figure"7:"Organisms"from"the"Benthic"zone."Every"one"a"Manchester"United"Fan

many"such"organisms"are"permanently"aHached"to"the"boHom."The"superficial "layer"of" the"soil"lining" the"

given"body"of" water"is "an"integral"part"of" the"benthic"zone," as"it"influences"greatly" the"biological"acFvity"

which"takes "place"there."Examples"of"contact"soil "layers"include"sand"boHoms,"rock"outcrops,"coral,"and"bay"

mud.

Habitats

Marine"habitats"are"environments"in"which"vegetaFon"and"marine"life"live."There"are"many"different"types"

of" habitat"within"the"widely" varying" areas"of" the"world," ranging" from"the"freezing" polar" ice,"through" the"



pelagic"zone,"deep"sea,"hydrothermal"vents,"mangrove,"sea"grass,"and"the"interFdal"zone"to"tropical"coral"

reefs." These" habitats " all" come" with" their" unique" challenges" and" are" inhabited" by" a" wide" variety" of"

organisms.

Ecological(Receptors(and(Values

Ecological"receptors"are"ecosystems,"habitats,"communiFes,"populaFons"and"individual"organisms"that"can"

be"exposed"directly"or" indirectly"to"a"stressor"where"a"stressor" is"a"physical,"chemical"or"biological "enFty"

that"induces"an"adverse"response"in"a"plant,"animal"or"ecosystem.

Ecological" values" are" the" plants," animals " or" ecosystems" that" are" idenFfied" and" considered" to" be" of"

significant" societal" relevance,"ecological" or" economical"significance." Ecological" values"may" be" generic" or"

specific"to"a"parFcular"site"or"habitat.

Fisheries

In" Trinidad" and" Tobago" recreaFonal" fishermen" generally" fish" from" boats" or" from" the" shore." These"

recreaFonal"fishermen" use" predominantly" hook" and" line" fishing" methods" such"as"aUlaUvive," trolling" and"

banking." Estuaries" (river" mouth)" are" parFcularly" popular" with" onUshore" fishermen." The" mouths "of" the"

Nariva"and"the"Ortoire"Rivers "are"prized"fishing"locaFons."Many"species"of"fish"enter"the"rivers "from"the"sea"

on"the"high"Fde"and"exit"on"the"low"Fde."Surf" fishing" is"also"popular"and"can"be"seen" from"almost"every"

beach"in"Trinidad."Indeed"it"is"a"common"pracFce"to"take"the"family"to"the"beach"for"a "swim"and"while"there"

try" your" luck"with" the"rod." Spear" fishing" in" conjuncFon" with" snorkelling" or" SCUBA" diving" has"grown" in"

popularity.

Marine(Mammals

Trinidad" has" the" last" remaining" populaFon" of" manatees "among" the"eastern" Caribbean" islands,"which" is"

composed"of"a "small"number"of" individuals"confined"to"a"small"swamp"on"the"east"coast"of"the"island."The"

Gulf" of" Paria"was"previously"called"‘Golfo"de"la"Ballena’"(Whale’s"Gulf)." "It"is "unclear" is"when"commercial"

whaling" began" in" the" area "but" whaling" is" considered" to" be" one" of" the" earliest" industries" of" Trinidad."

Commercial"whaling"most"likely"began"around"1826."The"results "of" this "exploitaFon"in"Trinidad"and"Tobago"

as"in"other"countries"in"the"area"that"pracFsed"intense"whaling,"local"populaFons"of"humpback"whales"have"

become"virtually"exFnct"in"their"waters.

In"2010," on" the"back"of" recent" pilot"whale" sighFngs"in" the"Gulf" of" Paria," the"opportunity"was" taken" to"

conduct" further"invesFgaFons,"making"use"of" the"tremendous"experFse"of" InternaFonal"Fund" for"Animal"

Welfare"in"marine"mammal"research"and"conservaFon."The"deployment"a"marine"electronic"depth"sounder"

that"can"detect"the"presence"of" aquaFc"life"off"Chacachacare"Island," registered"that"there"was"boHlenose"

dolphin"acFvity"in"the"area.



http://livepage.apple.com/

http://livepage.apple.com/

Hydrodynamics(and(the(Sedimentary(Regime

This "is "the" area"where"the"marine"biologists"considers "the"potenFal"impacts"of" the"dredging" project" on"

currents,"Fdes"and"wave"climate"within"the"dredging"and"disposal"areas,"as"well"as"the"potenFal"impacts"on"

the" sediment" regime." The" assessment" will " consider" the" impact" of" the" postUdredge" bathymetry" on" the"

hydrodynamics"and"sedimentary" regime"as"well" as" the" impact" of" the"dredging" operaFon" itself" on" local"

turbidity"and"sediment"deposiFon.

Water(Column

A"water"column"is "a"conceptual"column"of"water"from"surface"to"boHom"sediments."This"concept"is "used"

chiefly" for"environmental"studies"evaluaFng" the"straFficaFon"or"mixing"(e.g."by"wind"induced"currents)"of"

the" thermal"or"chemically"straFfied" layers"in"a"lake,"stream"or" ocean."Some"of" the"common"parameters"

analyzed" in" the" water" column" are:" pH," turbidity," temperature," salinity," total" dissolved" solids," various"

pesFcides,"pathogens"and"a"wide"variety"of"chemicals"and"biota.

Figure"8:"Typical"Water"column"in"the"ArcFc"region

The" concept" of" water" column" is"quite" important," since"many" aquaFc"phenomena" are" explained"by" the"

incomplete"verFcal"mixing"of" chemical,"physical"or"biological"parameters."For"example,"when"studying" the"

metabolism"of"benthic"organisms,"it"is"the"specific"boHom"layer"concentraFon"of"available"chemicals"in"the"

water"column"that"is "meaningful,"rather"than"the"average"value"of" those"chemicals"throughout"the"water"

column."The"process"of"dredging"onen"dislodges"chemicals"residing"in"benthic"substrates"and"injects"them"

into"the"water"column.

Turbidity

Turbidity" is"degree"of" the"cloudiness "of" the"water"caused"by"parFcles"of"suspended"solids."The"individual"

parFcles"are"likely"to"be"invisible"to"the"naked"eye,"not"unlike"smoke"in"air."The"measurement"of"turbidity"is"



a"key"test"of"water"quality."The"suspended"solid"maHer"will"contain"parFcles"of"many"different"sizes."Some"

of" the" " suspended"material"will "be"large"enough"and"heavy"enough"to"seHle"rapidly" to"the"boHom"if" the"

body"of"water"is"undisturbed."The"very"small"parFcles"will"seHle"very"slowly"if"at"all."

"



6:(Environmental(Impact(of(a(Dredging(Opera5on

Corporate(Responsibility

The"port’s"Marine"OperaFons"Department"(or"equivalent)" would"have"idenFfied"the"need"to"dredge."The"

Marine"department"would"arrange"for"interim"hydrographic"surveys"to"be"done"and"reported"periodically"

and"also"observe"or"obtain"feedback"from"the"echo"sounder"readings"of"ships"transiFng"the"channel.

In"selecFng" a"contractor"to"perform"the"dredging,"the"port’s"senior"management"will"have"to"be"saFsfied"

that" the" work" can" be" performed" safely," efficiently," cost" effecFvely," legally" and" in" an" environmentally"

friendly" manner." MaHers" of" risk" management," statutory" compliance," occupaFonal" health" and" safety,"

environmental" policies," quality" assurance" standards" and" administraFon" (including" records" and" reports)"

have" to" be"agreed" between" port" management" and" the" selected" dredging" contractor" and"documented."

These" documents" will" become" part" of" the" document" package" when" the" applicaFon" is" made" to" the"

AuthoriFes"for"permission"to"dredge"and"dispose"of"spoil.

A"team"comprising"of"port"pracFFoners"with"experience"in"vessel"inspecFon,"safety"and"environmental"

disciplines"physically"inspects"the"equipment"and"obtains"copies"of"all"relevant"cerFficates"and"

documentaFon."Of"course,"these"days"most"documents"can"be"exchanged"via"email"long"before"the"vessels"

arrive"at"the"work"site.

The" port’s" Procurement" Department" ensures" that" the" purchasing" policies" and" contract" management"

procedures"are"followed"strictly."The"port’s"Financial"Department"has "to"be"saFsfied"that"cost"minimisaFon"

measures"are"taken.

The"port’s"Legal"Department"can"assist"with"seeking" permission"from"the"AuthoriFes"in"order" to"proceed"

with"the"dredging."The"various"authoriFes"in"Trinidad"and"Tobago"with"an"interest"in"dredging"operaFons"

include"the"MariFme"Services"Division"(MSD)" of" the"Ministry" of"Works"and"Transport,"the"Environmental"

Management" Agency" (EMA)," the"Ministry" of" Energy" and" Energy" Affairs" (MEEA)" and" the" Office" of" the"

Commissioner"of"State"Lands"in"the"Ministry"of"Agriculture,"Land"and"Marine"Resources."The"port’s"Health,"

Safety"and"Environment"Department"performs"due"diligence"on"behalf"of"the"company"with"regards"to"eco"

safety,"meaning"checking"the"adequacy"of"the"dump"site,"polluFon"of"coastal"areas,"disturbance"of"marine"

flora"and"fauna"in"the"channel.

Environmental(Impact(of(Dredging(Ac5vity

The"acFvity"of"dredging"has"the"potenFal"create"the"following"principal"impacts"to"the"environment:

- release"of"toxic"chemicals"(including"heavy"metals"and"PCB)"from"boHom"sediments"into"the"water"column."

- short"term"increases"in"turbidity,"which"can"affect"aquaFc"species"metabolism"and" interfere"with"spawning."

- secondary" effects"from"water" column" contaminaFon"of" uptake" of" heavy"metals," DDT" and" other"persistent"organic"toxins,"via"food"chain"uptake"and"subsequent"concentraFons "of" these"toxins "in"higher"organisms"including"humans."

- secondary"impacts"to"marsh"producFvity"from"sedimentaFon"- terFary"impacts"to"avifauna"which"may"prey"upon"contaminated"aquaFc"organisms"



- secondary"impacts"to"aquaFc"and"benthic"organisms'"metabolism"and"mortality- possible"contaminaFon"of"dredge"spoil"disposal"sites"

The"CEC"applicaFon"includes"the"requirement"to"take"samples"of"the"sediment"to"be"dredged"and"the"water"

column" and" have" them" analysed" for" a "prescribed" suite"of" toxins." Similar" sampling" and" analysis" of" the"

disposal"site"can"also"be"requested.

Dredged(Spoil

Dredge" spoil" is" the"material" removed" by" dredging." Dredge" spoil" disposal" is" the" deposiFng" of" dredged"

materials"on"land"or"into"water"bodies "for"the"purpose"of"either"creaFng"new"or"addiFonal"lands"for"other"

uses"or"disposing"of"the"byUproducts"of"dredging.

Figure" 9:" OpFons" for" Trailing" SucFon" Hopper" Dredger" disposing" spoil." Labels" are:" further" recycling" as"

building"materials"on"land,"sediment"removal"by"dredging,"dumping.

Adapted"from"hHps://wwwUold.marum.de/Binaries/Binary10363/baggergutverwendung.gif"

In"a"hopper"dredger,"the"dredged"materials"end"up"in"a"large"onboard"hold"called"a""hopper"."A" hopper"

dredge"usually" has"doors "in" its "boHom" to" empty" the"dredged"materials,"but" some"dredges"empty" their"

hoppers"by"splisng"the"two"halves"of" their"hulls "on"giant"hinges."Either"way,"as"the"vessel "dredges,"excess"

water" in"the"dredged"materials"is"spilled"off"as"the"heavier"solids"seHle"to"the"boHom"of" the"hopper."This"

excess"water"is"returned"to"the"sea "to"reduce"weight"and"increase"the"amount"of"solid"material"(or"slurry)"

that"can"be"carried"in"one"load."When"the"hopper"is"filled"with"slurry,"the"dredger"stops "dredging"and"goes"

to"a"dump"site"and"empFes"its"hopper.

Some"hopper"dredges"are"designed"so"they"can"also"be"empFed"from"above"using"pumps"if"dump"sites"are"

unavailable"or" if" the" dredge"material" is "contaminated." SomeFmes" the"slurry" of" dredgings" and"water" is"

pumped"straight"into"pipes"which"deposit"it"on"nearby"land."Other" Fmes,"it" is"pumped"into"barges"(also"

called"scows),"which"deposit"it"elsewhere"while"the"dredge"conFnues"its"work.



https://www-old.marum.de/Binaries/Binary10363/baggergutverwendung.gif

https://www-old.marum.de/Binaries/Binary10363/baggergutverwendung.gif

Figure"10:"Clamshell"dredger"with"a"bucket"full"from"the"seabed.

Dredged(Spoil(Characteris5cs

The"following"informaFon"should"be"determined"for"all"dredged"spoil"to"be"disposed"of"at"sea:"

- Gross"wet"tonnage- Method"of"dredging"- Visual"determinaFon"of"sediment"characterisFcs"(clayUsilt/sand/gravel/boulders).

Assessing)poten;al)impact)on)disposal)sites

Further"informaFon"about"dredged"spoil"is"required"to"fully"assess"the"impact"it"will"have"on"the"disposal"

sites."This"informaFon"might"be"available"from"exisFng"sources,"e.g."from"field"observaFons"on"the"impact"

of"similar"material"at"similar"sites "or"from"previous"test"data"on"similar"material"tested"not"more"than"five"

years "previously"and"knowledge"of" local"discharges"or"other"sources"of" polluFon,"supported"by"a"selecFve"

analysis."

The"purpose"of"tesFng"is "to"establish"whether"the"disposal"at"sea"of"dredged"spoil"containing"contaminants"

might"cause"undesirable"effects,"especially" the"possibility"of"chronic"or"acute"effects"on"marine"organisms"

or"human"health,"whether"or"not"arising" from"their"bioaccumulaFon"in"marine"organisms"and"especially"in"

food"species.

Chemical"characterisaFon"is"the"necessary"first"step" to"esFmate"gross"loading"of"contaminants,"especially"

for"new"arisings"of"dredged"spoil."

If" previous"analysis"of" the"material"shows"the"presence"of" contaminants"in"considerable"quanFFes"or"of"

substances" whose" biological" effects" are" not" understood" and" if" there" is" concern" for" antagonisFc" or"

synergisFc"effects"of"more" than"one"substance," or" if" there" is"any" doubt" about"the"exact" composiFon" or"



properFes" of" the"material," it" may" be" necessary" to" carry" out" suitable" biological" test" procedures." These"

procedures"may"include"the"following:

- Acute"toxicity"tests;- Chronic"toxicity"tests"capable"of"evaluaFng"longUterm"sub"lethal"effects,"such"as"bioassays"covering"

an"enFre"life"cycle;- Tests"to"determine"the"potenFal"for"bioaccumulaFon"of"the"substance"of"concern

Where" it" can" be" established" that" the" dredged" spoil" is " substanFally" similar" in" physical" and" chemical"

properFes"to"the"sediments"at"the"proposed"disposal"site,"biological"tesFng"may"not"be"necessary"providing"

the"cumulaFve"impacts "at"the"disposal"site"will"not"exceed"the"environmental"management"objecFves"for"

the"area"concerned."More"details"on"the"required"tests "are"available" from"the"EMA"and" from"the"Spree"

Spirit"publicaFon,"‘Guidelines"for"Maintenance"Dredging"in"Trinidad"and"Tobago’.

Disposal(Site(Selec5on

Site"selecFon"to"minimize"impact"on"commercial"and"recreaFonal"fishing"areas "is "a"major"consideraFon"in"

resource"protecFon."Proper"disposal"site"selecFon"rather"than"tesFng"applicaFon"is"recommended.

Disposal"site"informaFon"to"be"considered"by"authoriFes"at"a"very"early"stage"of" assessment"of"a"new"site"

should"include"the"laFtude"and"longitude"coordinates"as"well"as"its"locaFon"with"regard"to:

- Distance"to"nearest"coastline- Depth- RecreaFonal"areas- Spawning"and"nursery"areas- Known"migraFon"routes"for"fish"or"marine"mammals- Sport"and"commercial"fishing"areas- Areas"of"natural"beauty"or"significant"cultural"or"historical"importance- Areas"of"special"scienFfic"or"biological"importance"(marine"sanctuaries)- Shipping"lanes- Military"exclusion"zones- Engineering" uses" of" seafloor" (e.g." potenFal" or" onUgoing" seabed" mining," undersea" cables,"

desalinaFon"or"energy"conservaFon"sites"

The"basic"assessment"of" a"site,"either"new"or"exisFng,"shall" include" the"consideraFon"of" possible"effects"

that"might"arise"by" the"increase"of" certain"consFtuents"or"by"the"interacFon"(e.g."synergisFc"effects)"with"

other"substances" introduced"in"the"area,"either"by"other" dumping"or" by"river" input"and"discharges"from"

coastal" areas," by" exploitaFon" areas"and" mariFme" transport," as"well" as" through" that" atmosphere." The"

exisFng"stress"on"biological"communiFes"as"a"result"of" such"acFviFes"should"be"evaluated"before"any"new"

or"addiFonal"disposal"operaFons"are"established."The"possible"future"uses"of" the"sea"area"should"be"kept"

under"consideraFon.

InformaFon"from"baseline"and"monitoring"studies"at"already"established"dumping"sites"will"be"important"in"

the"evaluaFon"of"any"new"dumping"acFvity"at"the"same"site"or"nearby."For"maintenance"dredging"projects,"

previously"used"disposal"sites"will"most"likely"be"suggested"and"the"challenge"will"more"likely"be"whether"

industrial" acFvity," such" as" drilling" and" or" pipe" laying" is" in" progress." CommunicaFon" between" the"

stakeholders"will"help"decide"if"and"how"spoil"disposal"can"occur"as"a"simultaneous"operaFon.



Disposal)Site)Characteris;cs

When"dredging"operaFons"are"intended,"the"scoping"would"recommend"preliminary"studies "to"determine"

whether" the" proposed" disposal" sites" possess" species "or" assemblages" of" unique"or" parFcular" biological"

interest"and"to"provide"a"baseline"with"which"to"compare"future"effects"aner"disposal"has"occurred.

In"order"to"assess"the"capacity"of"the"area"for"receiving"dredged"spoil"both"the"total"amount"of"material"and"

the"anFcipated"or"actual"loading"rate"at"the"disposal"site"should"be"taken"into"account.



7:(Dredging(and(Disposal(Site(Sampling(and(Analysis

Sediment"sampling"in"the"Gulf"of"Paria "usually" involves"one"metre"long"and"approximately"ten"cenFmetre"

diameter"pipe"being"pushed"into"the"silt"at"various "locaFons"(as"prescribed"by"EMA"guidance)"and"removed"

with"the"contents"intact."There"are"other"types"of"sampling"and"analysis.

Side(scan(sonar

Side"scan"sonar"is"a"tool"that"is"used"to"efficiently"create"an"image"of"large"areas"of"the"sea"floor."It"is"used"

for"mapping"the"seabed"for"a "wide"variety"of" purposes,"including"creaFon"of"nauFcal"charts"and"detecFon"

and" idenFficaFon" of" underwater"objects "and" bathymetric" features." It"may"be" used," in" conjuncFon"with"

seafloor"samples,"to"conduct"surveys"capable"of"providing"an"understanding"of" the"differences"in"material"

and" texture"type"of" the"seabed." Side" scan" sonar" imagery" is"also"a"commonly"used" tool" to" detect" debris"

items"and"other"obstrucFons"on"the"seafloor"that"may"be"hazardous"to"shipping"or"to"seafloor"installaFons"

by" the" oil" and" gas" industry." In" addiFon," the" status" of" pipelines" and" cables" on" the" seafloor" can" be"

invesFgated" using" sideUscan" sonar." SideUscan" data" are" frequently" acquired" along" with" bathymetric"

soundings"and"subUboHom"profiler"data,"thus"providing" a"glimpse"of"the"shallow"structure"of"the"seabed."

Side"scan"sonar"is"also"used"for"fisheries"research,"dredging"operaFons"and"environmental"studies.



Figure"11:"Side"scan"sonar"in"acFon

Video(‘Splashcam’(drops(

These"are"cameras"that"can"be"just""dropped""into"the"water."Some"manufacturers"claim"some"models"of"

underwater"camera"provide"broadcast"quality"video"and"superUhigh"resoluFon"color,"even"under"lowUlight"

condiFons."These" are"used" to"determine"major" habitat" boundaries"and" the"presence"of" major" epifauna"

habitats.



Figure"12:"Video"Splashcam"monitor.

Benthic(grab(survey

If"the"job"is"being"done"properly,"sediment"samples "have"to"be"tested"for"toxicity,"organic"content,"oxygen"

concentraFon,"sediment"type"and"grain" size"parameters"in"the"laboratory."Grab"samples"may"be"washed"

and"sieved"to"separate"organisms"from"the"sediment."The"organisms"are"then"idenFfied"and"enumerated."

Grab" samplers" are" relaFvely" light" and" easy" to" operate;" however," the" sediments" are" disturbed" during"

sampling,"so"grab"samples"will"not"yield"informaFon"about"sediment"structure."Grab"samplers"are"designed"

for"son"sediments,"so"hard"boHom"or"reef" structures"cannot"be"sampled"effecFvely" using" grab"samplers."

Grab" sample" analysis" can" be" FmeUconsuming" and" expensive" since" samples" must" be" analyzed" in" a"

laboratory." There" are" several" different" models " of" grab" samplers;" however," each" one" has" a" similar"

mechanism"for"collecFng"the"sample."The"open"sampler"is"lowered"to"the"seafloor,"where"it"penetrates "the"

sedimentUwater"interface"and"then"closes."The"device"is "then"raised"to"the"surface"with"the"intact"sediment"

sample." Benthic" grab" sampling" gives" quanFtaFve" esFmates" of" relaFve"density" and" species" richness" of"

macro"benthic"infauna.

Physical(Impact(of(Dredged(Spoil(Disposal

All"dredged"spoils,"whether"contaminated"or"not,"have"a"significant"physical"impact"at"the"point"of"disposal."

This " impact" includes" the" covering" of" the" seabed" (and" smothering" of" the" benthic" organisms)" and" local"

enhancement" of" suspended" solid" levels." Physical" impact" may" also" result" from" the" onward" transport"

parFcularly"in"finer"fracFons,"by"wave"and"Fdal"acFon"and"residual"current"movements.

In" relaFvely" enclosed" waters," such" as" some" estuarine" situaFons," oxygenUconsuming" sediments" could"

adversely"affect"the"oxygen"regime"of"the"disposal"sites.

In"the"open"sea,"blankeFng"of"the"seabed"is"usually"the"most"significant"physical"effect."The"impact"of" the"

dredged"spoil"on"the"suspended"solids"regime"in"most"coastal"waters"onen"will"be"transient"or"negligible.



Biological"consequences"of"these"physical"impacts"include"smothering"of"benthic"organisms"in"the"disposal"

site."Disposal"may" in"some"cases"interfere"with"the"migraFon"of" fish" (e.g." the"impact"of" high"turbidity"on"

salmonoids "in"estuarine"areas)"or"of"crustacean"(e.g."if"deposiFon"occurred"in"the"coastal"migraFon"path"of"

crabs).

An"important"consequence"of"the"physical"presence"of"dredged"spoil"disposal"acFviFes"is"interference"with"

fishing" acFviFes" and," in" some" instances," with" navigaFon" and" recreaFon." The" former" relates" to" both"

smothering" of" areas " potenFally" used" for" fisheries" and" interference" with" fixed" fishing" gear;" shoaling"

following" dumping" can" lead" to" navigaFonal" hazards" and" clay" or" silt" deposiFon"may" be" a "nuisance" in"

recreaFonal"areas." These" problems" can" be" aggravated" if" the" spoil" is "contaminated" with"bulky" harbour"

debris"such"as"wooden"beams,"scrap"metal,"pieces"of"cable"etc.

Figure"13:"Business"end"of"TSHD"sucFon.

Managing)the)Physical)Effects)of)Dredged)Spoil)Disposal

The"most"important"factor"in"the"management"of"the"physical"effects"of"dredged"spoil "disposal "is"by"careful"

site"selecFon"along"with"an"assessment"of"conflict"between"marine"resources"and"acFviFes."In"most"cases,"

blankeFng"of"an"area"of"seabed"is "accepted"as "an"environmental"cost"of"disposal."To"avoid"excessive"use"of"

the"seabed,"the"number"of" sites"should"be"limited"as"far"as"possible"and"each"site"should"be"used" to" the"

maximum"extent"possible"without"interfering"with"navigaFon."Once"deposiFon"stops,"hydrodynamic"forces"

will"resort"the"nature"of" the"sediments "and"reUcolonisaFon"is"usually"rapid."In"some"cases,"it" is"noted"that"

old"spoil"sites"become"producFve"new"fishing"areas.

Effects " can" be" minimized" by" ensuring" as" far" as" possible" that" the" sediments " in" the" dredged" spoil" and"

receiving" area" are" similar." Locally," biological" impact" may" be" further" reduced" if" the" deposiFon" area " is"

naturally"subject"to"physical"disturbance."Where"this"is"not"possible,"consideraFon"should"be"given"where"

clean,"fine"materials"are"concerned"to"a "deliberately"dispersive"style"of"disposal"to"reduce"blankeFng"on"a"

small"site.

With"capital"and"maintenance"dredging,"the"material"may"be"different"in"character"to"the"sediments"at"the"

receiving" site"and"colonisaFon"may"be"less"rapid."Where"bulky"material"such"as"rock"and"clay"material"is"

deposited,"there"may"be"interference"with"fishing"acFvity,"even"in"the"long" term."It"may"prove"possible"to"



use"capital "materials"in"the"construcFon"of"arFficial"reefs"for"fishery"or"recreaFonal"purposes"or"for"habitat"

creaFon;"in"this"case,"advice"from"ecologists"or"fishery"biologists"is"essenFal.

The" infilling" of" depressions" or" deliberate" capping" of" dredged" spoil" deposits" may" be" used" in" certain"

circumstances"to"avoid"interferences"with"fishery"or"other"legiFmate"acFviFes.

Interference"with"fish"or"crustacean"migraFon"or"spawning"or"with"seasonal"fishery"acFvity"may"be"avoided"

by" Fming" restricFons"on" disposal" acFvity." Trench" digging" and" refilling" acFviFes"may"also" interfere"with"

migratory"paHerns;"similar"controls"are"appropriate."In"miFgaFng"the"impact"of"disposal"within"estuaries"on"

migraFng"fish,"silt"screens"have"been"used" to"reduce"the"suspended"solids"levels,"but"these"have"proved"

hard"to"manage"effecFvely.

Disposal"vessels"and"operaFons"should"be"inspected"regularly"to"ensure"that"the"condiFons"of"the"disposal"

permit" are"being" complied"with" and" that" the" crew" is"aware" of" their" responsibiliFes" under" the"permit."

Where"rubbish"is"a "problem," it"may"be"necessary" to" specify"that"the"disposal"vessel"(or" dredger)" is "fiHed"

with"a"grid"to"facilitate"removal"for"disposal"(or"recovery)"on"land,"rather"than"being"dumped"at"sea."Ships'"

records"should"be"inspected"to"ensure"that"disposal"is"taking"place"at"the"specified"disposal"site.

Disposal)Site)Dispersal)Characteris;cs

The"use"of"dispersive"sites"even"for"the"disposal"of"sediments"with"low"levels"of"contaminaFon"is "not"devoid"

of" environmental" risk" and" requires "consideraFon" of" the" fate"and"effects"of" dispersed"material." There" is"

evidence"to"suggest"that"at"certain"wellUchosen"estuarine"sites,"dredged"spoil"may"enhance"the"habitats"of"

desired"species."

For"evaluaFon"of"dispersal"characterisFcs,"data"should"be"obtained"on"the"following:

- water"depths"(maximum,"minimum"and"mean)- water" straFficaFon" in" various" seasons"and" weather" condiFons "(depth" and" seasonal"variaFon" of"

pycnocline)- Fdal"period,"orientaFon"of"Fdal"ellipse,"velociFes"of"minor"and"major"axis- mean"surface"drin"(net):"direcFon"and"speed- mean"boHom"drin"(net):"direcFon"and"speed- storm"(wave)"induced"currents"(velociFes)- wind"and"wave"characterisFcs,"average"number"of"storm"days"per"year- concentraFon"and"composiFon"of"suspended"solids

Impact(Hypothesis

The"Impact"Hypothesis "is"an"aHempt"at"predicFng"the"effects"of"the"dredging"and"disposal"on"the"physical,"

chemical" and" biological" environment." An" Impact" Hypothesis" should" integrate" informaFon" on" the"

characterisFcs"of" the"dredged"spoil"and"proposed"disposal"site"condiFons."The"aim"is"to"provide"a"concise"

scienFfic"analysis" of" the"potenFal" effects"on" human" health," living" resources,"marine" life," ameniFes"and"

other" legiFmate"uses"of" the"sea." It" should" encompass"both" the"temporal"and" spaFal"scales"of" potenFal"

effects.

The"primary" areas"of" potenFal" impact" should" be" idenFfied"and" are" those" considered"to" have" the"most"

serious"consequences" for" human"health" and" the"environment."AlteraFons" to" the" physical" environment,"

risks "to"human"health,"devaluaFon"of"marine"resources,"and"interference"with"other"legiFmate"uses"of" the"



sea"are"onen"seen"as"prioriFes"in"this"regard.

Recommenda5ons(for(monitoring(the(Disposal(site

Substances" in" dredged" spoil"may" undergo" physical," chemical "and" biological"changes"when" entering" the"

marine"environment."The"suscepFbility"of"dredged"spoil"to"such"changes"should"be"considered"in"the"light"

of" the" eventual" fate" and" potenFal" effects" of" the" dredged" spoil." This" may" be" reflected" in" the" Impact"

Hypothesis"and"also"a"monitoring"programme.

The"purposes"of"monitoring" are"to"determine"contaminant" levels"in"organisms,"the"biological"effects"and"

consequences"for"the"marine"environment"due"to"the"dumping"of"dredged"spoil"and"to"allow"managers"to"

control"exposures"of"the"organisms"of"concern"to"dredged"spoils"and"associated"contaminants.

The"monitoring"programme"would"consider:

• The"recolonisaFon"rate"for"macro"benthic"fauna"aner"spoil"disposal"in"the"main"disposal"area;• Changes"in"the"composiFon"of" the"assemblage"relaFve"to"preUdisposal "baselines"and"unimpacted"

control"sites;• The"extents"of"movement"of"dredge"spoil"in"space"and"Fme;• Effects "of" sediment"deposiFon"at"varying"intensiFes"(i.e."varying"distances"from"the"disposal"site,"

measured"with"sediment"traps"and/or"sediment"profiling)"on"assemblage"composiFon;• The"recolonisaFon"Fme"of"assemblages"under"varying"sedimentaFon"scenarios



8:(Cer5ficate(of(Environmental(Clearance

Maintenance(Dredging(Sediment(Reten5on

The"CEC"sFpulates"as"a"condiFon"that"sediment"retenFon"measures"shall"be"uFlised,"as"pracFcable,"prior"to"

the"commencement"of" all"dredging" and"disposal"acFviFes"to"minimise"reUsuspension"of" sediments"in" the"

near"shore"coastal"waters."These"sedimentUretenFon"measures"can"include,"but"are"not"limited"to:"

Establishment"of" floaFng" turbidity" barriers "such" as"silt" curtains"or" gunderbooms"to" minimise" sediment"

dispersion"in"the"near"shore"coastal"environment;

Ensuring"a "single"grab"methodology"uFlising"clamshell"buckets"for"sediment"collecFon"to"prevent"waves"of"

suspended"sediments."

The"CEC" states"the"type"of" dredging" equipment,"as"requested"on"the"applicaFon" form,"to"be"used" in" the"

operaFon." In"most" cases" of" maintenance"dredging" in" the"Gulf" of" Paria"a" Clamshell" (Grab)" Dredger"and"

Trailing"SucFon"Hopper"Dredger"(TSHD)"would"be"the"main"types"of"dredge"equipment"used"to"conduct"the"

dredging"acFviFes"of"the"approach"channel"and"turning"basin."

During"the"maintenance"dredging"of" the"LNG"terminal"channel"in" 2002,"approximately" 2.74"million"cubic"

meters"of"dredge"spoil"was"disposed"in"the"offshore"disposal"site"off"La"Brea." "To"determine"the"extent"of"

the"sediment"plume"generated"by"the"disposal "of" the"dredge"material"at"the"offshore"site"and"the"way"in"

which"the"dredge"spoil"will"seHle,"six" sources "(shown"in"Figure"14)"were"used"to" study" the"dispersion"of"

sediments"in"the"region"of" the"proposed"disposal"site"(carried"out"in"the"2002"modelling"exercise)." "Figure"

15"below"shows"the"locaFon"of" the"dumpsite"used"in"the"model"and"the"model"boundaries"used"to"input"

effects"of"wind,"current"and"waves"in"the"area.

Figure"15"below"shows"the"model"dispersion"of"sediment"from"the"disposal"site.""The"material"is"disposed"as"

a"pulse"at"alternaFng"sites"within"the"disposal"area.""The"material"does"not"move"further"than"a"distance"of"

approximately"1km"from"the"site"based"on"the"results"of"the"mud"transport"modelling.""The"material"seHled"

to"the"seabed"in"a "flat"mound"shaped"formaFon"and"eventually"may" spread"evenly"over"the"seabed"with"

Fme.""Subsequent"maintenance"dredging"operaFons"can"be"expected"to"yield"slightly"greater"volumes"than"

were"used"for"the"modelling.""As"can"be"seen"from"the"model"output,"dredge"spoil"will"not"be"dispersed"at"a"

far"distance"from"the"source"primarily"because"of" very" low"sea"bed"currents"and"the"very"gentle"slope"on"

the" seabed" at" this" locaFon." In" addiFon," the" current" flow" at" disposal" site" locaFon" is" parallel" to" the"

bathymetric" contours" and" generally" run" along" the" NE" –" SW" axis"and" so" there" will"not" be" transport" of"

sediment" plume" towards" the" shoreline"as"well" as" the" LABIDCO" channel" and" turning" basin." UlFmately,"

possibiliFes"for"reUsuspension"of"sediment"are"very" low"at"the"site"for"operaFonal"condiFons,"based"on"all"

previous"modelling"exercises.""

Based"on"the"above"analysis,"the"potenFal"impact"of" the"disposal"acFviFes"with"respect"to"the"producFon"

of" sediment" plumes" and" distribuFon" of" sediment" outside" the" disposal" site" was" not" expected" to" be"

significant.



Figure"14:"Modelled"results"for"the"deposiFon"of"the"dredge"spoil "in"the"disposal"site"off" La"Brea,"showing"

Net"SedimentaFon"[Sample"dumps"nearer" the"shoreline"are"more"aligned"to"the"Fdal"flow"axis "(NEU

SW)]

Figure"15:"Disposal"of" dredge"spoil"at"La"Brea"Disposal"Site."The"model"was"run"using" the"effects"of"wind,"

current"and"waves"on"the"hydrodynamics



Figure"16:"Dispersion"of" sediment"from"disposal"site."The"volume"disposed"of" is "based"on"a"load"equal"to"

1350"m3"with"an"average"dry"density"of"500kg/m3

Hydrocarbon]contaminated(run]off

The"condiFon" on" the"CEC" related" to" this "states" the"hydrocarbonUcontaminated" runUoff" from" the"dredge"

vessel " shall" be" treated" to" ensure" a " maximum" discharge" concentraFon" of" 40mg/L" Total" Petroleum"

Hydrocarbons" (TPH)" in" accordance" with" the" Second" Schedule" of" the" Water" PolluFon" Rules" 2001" (as"

amended)"(WPR)."Effluent"from"the"vessel"that"may"contain"oily"material"shall"be"sampled"and"analysed"for"

TPH"at"least"once"during" the"proposed"acFvity."This "report"shall"be"made"available"to"the"Environmental"

Management"Agency"for"review"upon"request.

The" potenFal" sources" of" this" hydrocarbonUcontaminated" run" off" will" include" lube" oil " and" FO" purifiers,"

engine"and"machinery"oil"changes,"engine"cylinder"oil"drains,"main"engine"lube"and"FO"system"leak"offs."The"

controls"to"miFgate"the"risk" of" hydrocarbonUcontaminated" run"of" include"preventaFve"maintenance"and"

daily" inspecFons"of"machinery"and"equipment"would"minimise"releases."All"acFviFes"conducted"on"board"

shall"be"planned"and"controlled"to"minimise"releases."There"shall"be"no"hydrocarbonUcontaminated"runUoff"

from"dredge"vessel."

Any"sludge"and"or"oily"water"from"maintenance"acFviFes"will"be"stored"temporarily" in"tanks"on"board"the"

vessel."The"dredge"operator"will"arrange"for"the"sludge/oily"water"to"be"pumped"off"the"vessel"into"a"slop"

barge"or"truck"at"the"LABIDCO" Port"pending"disposal"at"an"approved" facility."All"operaFons"involving"and"



movements"of"hydrocarbons"shall"be"recorded"in"the"Oil"Record"Book"for"Ships"including"details"such"as"

quanFty"and"the"vessel’s"posiFon.

Noise(and(Vibra5on

The"CerFficate"of"Environmental"Clearance"will"state"its"condiFons"with"regard"to"noise."These"will"typically"

be"that" pursuant" to" the"Noise"PolluFon"Control"Rules," if" dredging" acFviFes"occur" outside"the"hours"of"

0700hrs"and"1900hrs"of" any"day"and" in"the"event" that"noise"levels"are"expected"to"exceed"the"standards"

specified" in" the"Noise"PolluFon"Control "Rules," the"applicant"shall "apply" for" and"obtain"a "Noise"VariaFon"

from"the"Environment"Management"Agency"before"proceeding"with"site"acFviFes.

Sewage

The"discharge"of" sewage" into"the"sea"is "prohibited,"except"when" the"ship"has"in"operaFon" an" approved"

sewage"treatment"plant"or"is "discharging"comminute"and"disinfected"sewage"using"an"approved"system"at"a"

distance"of"more"than"5.6km"(three"nauFcal"miles)" from"the"nearest"land."An"approved"on"board"sewage"

treatment"plant"shall"meet"the"standards"and"tests "outlined"in"the"revised"Guidelines"on"ImplementaFon"of"

Effluent"Standards"and"Performance"Test"for"Sewage"Treatment"Plants,"the"Marine"Environment"ProtecFon"

CommiHee"(MEPC),"October"13,"2006

MARPOL(73/78

Parameter Resolu5on(MEPC.2(VI)

3(Dec(1976

Resolu5on(MEPC.159(55)

13(Oct(2006Faecal"Coliform 250/100ml 100/100mlTotal"Suspended"Solids 50"mg/l"(on"shore) 35"mg/l"(on"shore)Biochemical"Oxygen"Demand" 50"mg/l 25"mg/l



Waste(Matrix

Waste(Stream Recommenda5on L e g i s l a 5 v e(

Requirements

Evidence(of(comple5on

Non" Hazardous" Solid"

Wa s t e" ( p a c k a g i n g"

materials," containers,"

liHer," food" containers,"

beverage" cans," coffee"

cups ," paper" bags ,"

rubber," wood," steel,"

scrap" metals," pipes,"

electrical"cusngs,"nonU

h a z a r d o u s " p a r t s ,"

Styrofoam)

K e e p" r e c y c l a b l e s"

(cardboard," plasFc" boHles,"

glass" boHles," aluminium"

cans," paper)" in" separate"

b a g s" a n d" p l a c e" i n"

designated" skip" " pending"

transfer" to" designated"

receptacle" on" the" port"

facility."Other"waste"should"

be" kept" separated" and"

placed"in"designated"skip"in"

an"appropriate"locaFon.

MARPOL"Annex"V"

CEC2673/2009"

SecFon"ii"(n)

D redge r ’ s" Ga rbage"

Record"Book

Chemica l s /Med ica l"

Waste

C o l l e c t" w a s t e" i n"

compaFble," sturdy," leak"

proof" containers" with"

secure," leak" proof" lids" to"

ensure" no" leakage" of"

contents." Chemical" waste"

containers"must" be" clearly"

labelled" with" complete"

chemica l" names ." The"

dredging" contractor" " shall"

d i s po se" o f" wa s te" a s"

prescribed" in" MSDS." Note"

this"waste"type"shall"not"be"

incorporated" into" the"

general"waste"stream"in"an"

appropriate"locaFon.

CEC2673/2009"

SecFon"ii"(p)

MARPOL" Annex"

11

Disposal/DestrucFon"

CerFficate"from"disposal"

facility



Oily" Waste" including"

spent" lubricants," used"

oils,"sludge

All" visible" dirt," grime,"

grease," oil," loose" paint,"

etc.," would" be" removed"

from" the" equipment" prior"

to" use" at" the" site." All"

acFviFes" conducted" on"

board"shall"be"planned"and"

controlled." The" dredging"

contractor" will" arrange" for"

the"sludge/oily"water"to"be"

pumped"off"vessel"to"a"slop"

barge" in" an" appropriate"

locaFon" pending" disposal"

at"an"approved"facility.

CEC2673/2009"

SecFon"ii"(j)

MARPOL"Annex"1

T h e" d r e d g e r ’ s" O i l"

Record"Book



Ballast"Water" Ballast" water" shall" be"

disposed" of" as" per" IMO"

gu ide l i ne s ." E x change"

should" be" done" prior" to"

coming" in" channel." No"

exchange" of" ballast" water"

shou ld" be" conducted"

within" close" proximity" to"

channel

Wh e n e v e r" p o s s i b l e ,"

conduct" ballast" water"

exchange" at" least" 200"

nauFcal" miles" from" the"

nearest" land" and" in" water"

at" least" 200" metres" in"

depth," taking" into" account"

Guidelines" developed" by"

IMO;"

In" cases"where" the"ship" is"

unable" to" conduct" ballast"

water" exchange" as" above,"

this" should" be"as"far" from"

t h e" n e a r e s t" l a nd" a s"

possible,"and"in"all"cases"at"

least" 50" nauFcal" miles"

from" the"nearest" land" and"

in" water" at" least" 200"

metres"in"depth."

CEC2673/2009"

SecFon"ii"(o)

IMO

The" dredger’s" Ballast"

water"record"book



Sewage Sewage"can" be" treated" on"

board" using" an" approved"

sewage" treatment" plant"

that" would" meet" the"

specified" requirements."

Where"this"cannot"be"done"

sewage" can" be" collected"

from" the" ship" with" a"

mobile" vacuum" tanker" (or"

barge)"and"diverted"to"land"

to" be" t reated" by" an"

approved"facility.

MARPOL" Annex"

IV"

CEC2673/2009"

SecFon"ii"(q)

CerFficaFon" of" Sewage"

Treatment"Plant.

Dredging" contractor’s"

o p e r a F n g" a n d"

maintenance" program"

records

Grey"water G rey" wa te r" s ha l l" b e"

diverted" to" the" sewage"

treatment" plant" before"

disposal."

CEC2673/2009"

SecFon"ii"(r)

Same"as"sewage

Dewatered" Large" Solid"

Waste

Collect"from"the"vessel"and"

p l a c e" i n" d e s i g n a t e d"

container" at" recepFon"

facility"pending"disposal"at"

an"approved"landfill

CEC2673/2009"

SecFon"ii"(s)

Disposal/DestrucFon"

CerFficate"from"disposal"

facility

Dredge"Spoil D i s p o s e d" o f" a t" t h e"

designated" disposal" site"

offshore

CEC2673/2009"

SecFon"ii"(t)

NA"

Noise Tools ," machinery" and"

equipment" employed" for"

all" works" shall" be" fiHed"

w i th" adequa te" no i se"

reducing" apparatus." Noise"

measurements" will" be"

taken" at" the" start" of" and"

d u r i n g" t h e" p r o j e c t"

acFviFes.

CEC2673/2009"

SecFon"ii"(i)

Noise" measurement"

Report

Air C o n d u c t" r e g u l a r"

inspecFons" and" maintain"

all" equipment" used" during"

t h e" a c F v i t y" t o"

m a n u f a c t u r e r s ’"

specificaFons"

CEC2673/2009"

SecFon"ii"(h)

P o r t ’ s " I n s p e c F o n"

checklist



9:(CONCLUSIONS

The"Port"PracFFoner"will"be"the"person"who"will"most"likely"have"to"explain"dredging" to"environmentalists"

and" explain" environmental" concerns" to" port"management." " The" Port" PracFFoner"will" have" display" his"

principals’"sensiFvity"to"environmental"issues"and"at"the"same"Fme"return"his"port"to"normal"operaFons"as"

safely,"efficiently"and"cost"effecFvely"as"possible.

It"is"in"the"Port"PracFFoner’s"interest"to"have"a"working"knowledge"of"all"sides"of"this"operaFon.



APPENDICES

A.1(Types(of(Dredging

A.1.1)Capital)Dredging

This "is "dredging"carried"out"to"create"a"new"harbour,"berth"or"waterway,"or"to"deepen"exisFng"faciliFes"in"

order" to" allow" larger" ships"access." Because" capital"works "usually" involve"hard" material "or" highUvolume"

works,"the"work"is "usually"done"using"a"cuHer"sucFon"dredge"or"large"trailing"sucFon"hopper"dredge,"but"

for"rock"works"drilling"and"blasFng"along"with"mechanical"excavaFon"may"be"used."

A.1.2)Preparatory)Dredging

This "is"work"and"excavaFon"for"future"bridges,"piers "or"docks/wharves,"onen" connected"with"foundaFon"

work."

A.1.3)Maintenance)Dredging

This "is "dredging" to"deepen"or"maintain"navigable"waterways"or"channels "which"are"threatened"to"become"

silted"with"the"passage"of" Fme," due" to" sediment" sand" and"mud," possibly" making" them" too" shallow"for"

navigaFon."This "is"onen"carried"out"with"a"trailing"sucFon"hopper"dredge."Most"dredging"is"for"this"purpose,"

and"it"may"also"be"done"to"maintain"the"holding"capacity"of"reservoirs"or"lakes."This"is"the"type"of"dredging"

this"thesis"is"focussed"on."

A.1.4)Land)reclama;on

This "is "dredging"to"mine"sand,"clay"or"rock"from"the"seabed"and"using"it"to"construct"new"land"elsewhere."

This "is "typically"performed"by"a"cuHerUsucFon"dredge"or"trailing"sucFon"hopper"dredge."The"material"may"

also"be"used"for"flood"or"erosion"control."

A.1.5)Beach)nourishment)

This "is"the"mining"of"sand"offshore"and"placing"on"a"beach"to"replace"sand"eroded"by"storms"or"wave"acFon."

This "is"done"to"enhance"the"recreaFonal"and"protecFve"funcFon"of"the"beaches,"which"can"be"eroded"by"

human" acFvity" or" by" storms." This" is" typically" performed" by" a" cuHerUsucFon" dredge"or" trailing" sucFon"

hopper"dredge."

A.1.6)Harves;ng)materials

This"is"dredging"sediment"for"elements"like"gold"or"other"valuable"trace"substances."

A.1.7)Seabed)mining

A"possible"future"use"of"dredging,"recovering"natural"metal"ore"nodules"from"the"sea's"abyssal"plains."



A.1.8)Construc;on)materials

This " is" the" dredging" of" sand" and" gravels" from"offshore" licensed" areas "for" use" in" construcFon" industry,"

principally" for" use" in" concrete."This" is"a"very" specialist" industry" focused" in" NW" Europe"using" specialized"

trailing"sucFon"hopper"dredgers"self"discharging"dry"cargo"ashore."

A.1.9)An;Oeutrophica;on)

Dredging" is" an" expensive" opFon" for" the" remediaFon" of" eutrophied" (or" deUoxygenated)" water" bodies."

However,"as"arFficially"elevated"phosphorus"levels"in"the"sediment"aggravate"the"eutrophicaFon"process,"

controlled"sediment"removal"is"occasionally"the"only"opFon"for"the"reclamaFon"of"sFll"waters."

A.1.10)Contaminant)remedia;on

This "is"done"to"reclaim"areas "affected"by"chemical"spills,"storm"water"surges"(with"urban"runoff),"and"other"

soil"contaminaFons."Disposal"becomes"a"proporFonally"large"factor"in"these"operaFons."

A.1.11)Removing)trash)and)debris)

This "is "onen"done" in" combinaFon"with"maintenance"dredging," this"process" removes"nonUnatural"maHer"

from"the"boHoms"of"rivers"and"canals"and"harbors.

A.2(Types(of(Dredging(Vessels

A.2.1)Grab)Dredger

This "type"of"dredger"uses"a"clamshell"bucket"aHached"to"a "crane"on"the"vessel"to"dig"and"remove"sediment"

from"the"sea"floor."The"clamshell"bucket" is"opened"and" lowered"down" to"the"sea"floor."The"sides"of" the"

bucket"close,"grabbing" sediment"on"the"sea"floor."The"bucket"is"lined"and"empFed"into"the"barge"moored"

alongside"the"dredger.

A"grab"dredger"picks"up"seabed"material"with"a"clam"shell"grab,"which"hangs "from"an"onboard"crane"or"a"

crane"ship,"or"is "carried"by"a"hydraulic"arm,"or"is"mounted"like"on"a"dragline."This"technique"is "onen"used"in"

excavaFon"of"bay"mud."Most"of"these"dredges"are"crane"barges"with"spuds.

A.2.2)Trailing)Suc;on)Hopper)Dredger

A"TSHD"is"a"seaUgoing"selfUpropelled"vessel"equipped"with"one"or"two"sucFon"pipes,"designed"to"trail "along"

the"side"of"the"vessel.""At"the"lower"end"of"the"sucFon"pipe,"a"drag"head"is "fixed.""SucFon"is"" p rov ided"

by"a "centrifugal"pump,"which"discharges"the"mixture"of"soil"and"water"in"the"hopper"well"of"the"dredge."To"

start" the"dredging" operaFons," the" TSHD" will" sail" to" the"area" to"be"dredged."Once" in" the"vicinity" of" its"

dredging"area,"the"TSHD"will"lower"the"drag"head"to"the"sea"boHom"and"begin"dredging."The"dredge"pump,"

installed"inside"the"dredge"takes "up"a "mixture"of"water"and"soil"through"the"drag"head"and"sucFon"pipe"and"

pumps"the"mixture"into"the"hopper"well."When"the"draught"of"the"vessel"reaches"its "limit,"dredging"will"be"

stopped"and"the"sucFon"pipe"hoisted"on"deck."The"vessel"then"sails"with"the"dredge"spoil"to"the"offshore"



disposal"area,"where"the"load"is "deposited"by"opening"the"boHom"doors.""" Once" empty," the" vessel"

returns"to"the"dredging"area.

A" trailing" sucFon"hopper"dredger" (TSHD)" trails "its"sucFon"pipe"when"working,"and"loads"the"dredge"spoil"

into"one"or"more"hoppers"in"the"vessel."When"the"hoppers"are"full,"the"TSHD"sails "to"a"disposal"area"and"

either" dumps" the"material" through" doors" in" the" hull" or" pumps" the"material" out"of" the"hoppers." Some"

dredges"also"selfUoffload"using"drag"buckets"and"conveyors.

A.2.3)Suc;on)Dredger

These"operate"by"sucking"through"a"long"tube,"like"some"vacuum"cleaners"but"on"a"big"scale."A"plain"sucFon"

dredger"has"no"tool"at"the"end"of"the"sucFon"pipe"to"disturb"the"material."This"is"onen"the"most"commonly"

used"form"of"dredging.

A.2.4)CuSer)Suc;on)Dredger

A"cuHerUsucFon"dredger's"(CSD)"sucFon"tube"has"a"cuHer"head"at"the"sucFon"inlet,"to"loosen"the"earth"and"

transport"it"to"the"sucFon"mouth."The"cuHer"can"also"be"used"for"hard"surface"materials"like"gravel"or"rock."

The"dredged"soil"is"usually"sucked"up"by"a"wearUresistant"centrifugal"pump"and"discharged"through"a "pipe"

line"or"to"a"barge."In"recent"years,"dredgers"with"more"powerful"cuHers "have"been"built"in"order"to"excavate"

harder"rock"without"blasFng.

A.2.5)Auger)Suc;on

This "process"funcFons "like"a "cuHer"sucFon"dredger,"but"the"cusng"tool"is"a"rotaFng"Archimedean"screw"set"

at"right"angles"to"the"sucFon"pipe.

A.2.6)Jet)LiU

These" use" the"Venturi" effect" of" a" concentrated" highUspeed" stream" of" water" to" pull" the" nearby" water,"

together"with"bed"material,"into"a"pipe.

A.2.7)Air)LiU

An"airlin"is "a"type"of"small"sucFon"dredge."It"is "someFmes"used"like"other"dredges."At"other"Fmes,"an"airlin"

is "used,"handheld"underwater"by"a "diver."It"works "by"blowing"air"into"the"pipe,"and"that"air,"being" lighter"

than"water,"rises"inside"the"pipe,"dragging"water"with"it.

A.2.8)Bucket)dredging

A"bucket"dredger"is "equipped"with"a"bucket"dredge,"which"is "a"device"that"picks"up"sediment"by"mechanical"

means,"onen"with"many"circulaFng"buckets"aHached"to"a "wheel"or"chain."Some"bucket"dredgers"and"grab"

dredgers"are"powerful"enough"to"rip"out"coral"to"make"a"shipping"channel"through"coral"reefs.



A.2.9)Backhoe/Dipper

A"backhoe/dipper"dredge"has"a"backhoe"like"on"some"excavators."A"crude"but"usable"backhoe"dredger"can"

be"made"by"mounFng"a"landUtype"backhoe"excavator"on"a"pontoon."Small "backhoe"dredgers"can"be"trackU

mounted"and"work"from"the"bank"of"ditches."A" backhoe"dredger" is"equipped"with"a"halfUopen"shell."The"

shell" is"filled"moving"towards"the"machine."Usually"dredges"material"is" loaded" in"barges."This"machine"is"

mainly"used"in"harbors"and"other"shallow"water.

A.2.10)Water)Injec;on

A"water"injecFon"dredger"uses"a"small"jet"to"inject"water"under"low"pressure"(to"prevent"the"sediment"from"

exploding" into" the"surrounding" waters)" into"the"seabed"to"bring"the"sediment" in"suspension,"which" then"

becomes"a"turbidity"current,"which"flows"away"down"slope,"is "moved"by"a"second"burst"of"water"from"the"

WID"or" is"carried"away" in"natural"currents."Water"injecFon"results"in"a"lot"of" sediment"in"the"water"which"

makes"measurement"with"most"hydrographic"equipment"(for"instance:"singlebeam"echosounders)"difficult.

A.2.11)Pneuma;c

These"dredgers"use"a"chamber"with" inlets,"out"of"which"the"water" is"pumped"with"the"inlets"closed." It"is"

usually" suspended"from"a "crane"on" land"or"from"a "small"pontoon"or"barge."Its "effecFveness"depends"on"

depth"pressure.

A.2.12)Bed)leveler

This "is"a "bar"or" blade"which"is "pulled"over"the"seabed"behind"any" suitable"ship"or"boat." It"has"an" effect"

similar"to"that"of"a"bulldozer"on"land."In"Trinidad"and"Tobago"it"was"called"the"plough.

A.2.13)Amphibious

Some"of" these"are"any"of" the"above"types"of" dredger,"which"can"operate"normally,"or"by"extending"legs,"

also"known"as"spuds,"so"it"stands"on"the"seabed"with"its "hull"out"of" the"water."Some"forms"can"go"on"land."

Some"of"these"are"landUtype"backhoe"excavators"whose"wheels"are"on"long"hinged"legs"so"it"can"drive"into"

shallow"water"and"keep"its"cab"out"of"water."Some"of"these"may"not"have"a"floatable"hull"and,"if"so,"cannot"

work"in"deep"water.

A.2.14)Submersible

These"are"usually" used"to" recover"useful"materials"from" the"seabed."Many" of" them" travel"on"caterpillar"

tracks."A"unique"variant"is"intended"to"walk"on"legs"on"the"seabed."



READING(LIST

Journals:

NaFonal" InsFtute" of" Water" and" Atmospheric" Research" Ltd," New" Zealand," Benthic" Offshore" Surveys" of"

Proposed"Dredge"Spoil"Disposal"Sites"off"Otago"Peninsula.

"

Internet(pages:

hHp://www.dredging.org/documents/ceda/downloads/environmentUhelcomUdmguidelines.pdf

hHp://marinemanagement.org.uk/works/documents/environmental_statements/falmouth.pdf

hHp://en.wikipedia.org/wiki/Dredging

hHp://www.htgUbaggergut.de/Downloads/guide_rec13_1.pdf

hHp://www.cses.vt.edu/revegetaFon/dredge.html

hHp://www.coffsharbour.nsw.gov.au/

hHp://www.newsday.co.H/features/

hHp://www.teebweb.org/

hHp://www.imo.org/OurWork/Environment/BallastWaterManagement/

hHp://www.siue.edu/artsandsciences/pdf/deanspublicaFons/406.EnvironHistMarMammTrinidad.pdf

hHp://www.gsH.org/Geology/recent%20sediments.htm



http://www.dredging.org/documents/ceda/downloads/environment-helcom-dmguidelines.pdf

http://www.dredging.org/documents/ceda/downloads/environment-helcom-dmguidelines.pdf

http://marinemanagement.org.uk/works/documents/environmental_statements/falmouth.pdf

http://marinemanagement.org.uk/works/documents/environmental_statements/falmouth.pdf

http://en.wikipedia.org/wiki/Dredging

http://en.wikipedia.org/wiki/Dredging

http://www.htg-baggergut.de/Downloads/guide_rec13_1.pdf

http://www.htg-baggergut.de/Downloads/guide_rec13_1.pdf

http://www.cses.vt.edu/revegetation/dredge.html

http://www.cses.vt.edu/revegetation/dredge.html

http://www.coffsharbour.nsw.gov.au

http://www.coffsharbour.nsw.gov.au

http://www.newsday.co.tt/features/

http://www.newsday.co.tt/features/

http://www.teebweb.org/

http://www.teebweb.org/

http://www.imo.org/OurWork/Environment/BallastWaterManagement/

http://www.imo.org/OurWork/Environment/BallastWaterManagement/

http://www.siue.edu/artsandsciences/pdf/deanspublications/406.EnvironHistMarMammTrinidad.pdf

http://www.siue.edu/artsandsciences/pdf/deanspublications/406.EnvironHistMarMammTrinidad.pdf

http://www.gstt.org/Geology/recent%20sediments.htm

http://www.gstt.org/Geology/recent%20sediments.htm



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