terraet aqua...philip roland heleen schellinck roberto vidal martin hugo de vlieger iadc board of...

TERRAETAQUAMaritime Solutions for a Changing World

Number 108 | September 2007International Association of Dredging Companies

International Association of Dredging Companies

COVER

Traffic on the Panama Canal is constant, day and night, with more than 13,000 ships, from private yachts to

Panamax cargo vessels, transiting everyday. Even crucial dredging operations for deepening and widening the

Canal are not allowed to interrupt the flow of vessels (see page 27).

IADC

Constantijn Dolmans, Secretary General

Alexanderveld 84

2585 DB The Hague

Mailing adress:

P.O. Box 80521

2508 GM The Hague

The Netherlands

T +31 (70) 352 3334

F +31 (70) 351 2654

E [email protected]

I www.iadc-dredging.com

I www.terra-et-aqua.com

Please address enquiries to the editor. Articles in

Terra et Aqua do not necessarily reflect the opinion

of the IADC Board or of individual members.

Editor

Marsha R. Cohen

Editorial Advisory Committee

Roel Berends, Chairman

Constantijn Dolmans

Hubert Fiers

Bert Groothuizen

Philip Roland

Heleen Schellinck

Roberto Vidal Martin

Hugo De Vlieger

IADC Board of Directors

R. van Gelder, President

Y. Kakimoto, Vice President

C. van Meerbeeck, Treasurer

C. Marconi

P. de Ridder

P.G. Roland

G. Vandewalle

MEMBERSHIP LIST IADC 2007Through their regional branches or through representatives, members of IADC operate directly at all locations worldwide

AFRICADredging and Reclamation Jan De Nul Ltd., Lagos, NigeriaDredging International Services Nigeria Ltd., Ikoyi Lagos, NigeriaNigerian Westminster Dredging and Marine Ltd., Lagos, NigeriaVan Oord Nigeria Ltd., Ikeja-Lagos, NigeriaDredging International - Tunisia Branch, Tunis, TunisiaBoskalis South Africa, Pretoria, South Africa

ASIAFar East Dredging (Taiwan) Ltd., Taipei, Taiwan ROCFar East Dredging Ltd. Hong Kong, P.R. ChinaVan Oord ACZ Marine Contractors b.v. Hong Kong Branch, Hong Kong, P.R. ChinaVan Oord ACZ Marine Contractors b.v. Shanghai Branch, Shanghai, P.R. ChinaP.T. Boskalis International Indonesia, Jakarta, IndonesiaP.T. Penkonindo LLC, Jakarta, IndonesiaVan Oord India Pte. Ltd., Mumbai, IndiaBoskalis Dredging India Pvt Ltd., Mumbai, IndiaVan Oord ACZ India Pte. Ltd., Mumbai, IndiaJan De Nul Dredging India Pvt. Ltd., IndiaPenta-Ocean Construction Co. Ltd., Tokyo, JapanToa Corporation, Tokyo, JapanHyundai Engineering & Construction Co. Ltd., Seoul, KoreaVan Oord Dredging and Marine Contractors b.v. Korea Branch, Busan, Republic of KoreaBallast Ham Dredging (Malaysia) Sdn. Bhd., Johor Darul Takzim, MalaysiaTideway DI Sdn. Bhd., Kuala Lumpur, MalaysiaVan Oord (Malaysia) Sdn. Bhd., Selangor, MalaysiaVan Oord Dredging and Marine Contractors b.v. Philippines Branch, Manilla, PhilippinesBoskalis International Pte. Ltd., SingaporeDredging International Asia Pacific (Pte) Ltd., SingaporeJan De Nul Singapore Pte. Ltd., SingaporeVan Oord Dredging and Marine Contractors b.v. Singapore Branch, Singapore

AUSTRALIABoskalis Australia Pty. Ltd., Sydney, AustraliaDredeco Pty. Ltd., Brisbane, QLD, AustraliaVan Oord Australia Pty. Ltd., Brisbane, QLD, AustraliaWA Shell Sands Pty. Ltd., Perth, AustraliaNZ Dredging & General Works Ltd., Maunganui, New Zealand

EUROPEDEME Building Materials N.V. (DBM), Zwijndrecht, BelgiumDredging International N.V., Zwijndrecht, BelgiumInternational Seaport Private Ltd., Zwijndrecht, BelgiumJan De Nul n.v., Hofstede/Aalst, BelgiumN.V. Baggerwerken Decloedt & Zoon, Oostende, BelgiumBoskalis Westminster Dredging & Contracting Ltd., CyprusVan Oord Middle East Ltd., Nicosia, CyprusBrewaba Wasserbaugesellschaft Bremen m.b.H., Bremen, GermanyHeinrich Hirdes G.m.b.H., Hamburg, GermanyNordsee Nassbagger - und Tiefbau G.m.b.H., Wilhelmshaven, GermanyTerramare Eesti OU, Tallinn, EstoniaDRACE, Madrid, SpainDravo SA, Madrid, SpainSociedade Española de Dragados S.A., Madrid, SpainTerramare Oy, Helsinki, FinlandAtlantique Dragage S.A., Nanterre, FranceAtlantique Dragage Sarl, Paris, FranceSociété de Dragage International ‘SDI’ S.A., Lambersart, FranceSodranord SARL, Le Blanc - Mesnil Cédex, FranceDredging International (UK) Ltd., Weybridge, UK

Jan De Nul (UK) Ltd., Ascot, UKRock Fall Company Ltd., Aberdeen, UKVan Oord UK Ltd., Newbury, UKWestminster Dredging Co. Ltd., Fareham, UKIrish Dredging Company, Cork, IrelandVan Oord Ireland Ltd., Dublin, IrelandBoskalis Italia, Rome, ItalyDravo SA, Italia, Amelia (TR), ItalySocieta Italiana Dragaggi SpA ‘SIDRA’, Rome, ItalyEuropean Dredging Company s.a., Steinfort, LuxembourgTOA (LUX) S.A., Luxembourg, LuxembourgDredging and Maritime Management s.a., Steinfort, LuxembourgBaltic Marine Contractors SIA, Riga, LatviaAannemingsbedrijf L. Paans & Zonen, Gorinchem, NetherlandsBaggermaatschappij Boskalis B.V., Papendrecht, NetherlandsBallast Nedam Baggeren b.v., Rotterdam, NetherlandsBoskalis B.V., Rotterdam, NetherlandsBoskalis International B.V., Papendrecht, NetherlandsBoskalis Offshore b.v., Papendrecht, NetherlandsDredging and Contracting Rotterdam b.v., Bergen op Zoom, NetherlandsHam Dredging Contractors b.v., Rotterdam, NetherlandsMijnster zand- en grinthandel b.v., Gorinchem, NetherlandsTideway B.V., Breda, NetherlandsVan Oord ACZ Marine Contractors b.v., Rotterdam, NetherlandsVan Oord Nederland b.v., Gorinchem, NetherlandsVan Oord n.v., Rotterdam, NetherlandsVan Oord Offshore b.v., Gorinchem, NetherlandsVan Oord Overseas b.v., Gorinchem, NetherlandsWater Injection Dredging b.v., Rotterdam, NetherlandsDragapor Dragagens de Portugal S.A., Alcochete, PortugalDravo S.A., Lisbon, PortugalBaggerwerken Decloedt en Zoon N.V., St Petersburg, RussiaBallast Ham Dredging, St. Petersburg, RussiaBoskalis Sweden AB, Gothenburg, Sweden

MIDDLE EASTBoskalis Westminster M.E. Ltd., Abu Dhabi, U.A.E.Gulf Cobla (Limited Liability Company), Dubai, U.A.E.Jan De Nul Dredging Ltd. (Dubai Branch), Dubai, U.A.E.Van Oord Gulf FZE, Dubai, U.A.E.Boskalis Westminster Middle East Ltd., Manama, BahrainBoskalis Westminster (Oman) LLC, Muscat, OmanBoskalis Westminster Middle East, Doha, QatarBoskalis Westminster Al Rushaid Co. Ltd., Al Khobar, Saudi ArabiaHAM Saudi Arabia Company Ltd., Damman, Saudi Arabia

THE AMERICASVan Oord Curaçao n.v., Willemstad, CuraçaoCompañía Sud Americana de Dragados S.A., Buenos Aires, ArgentinaVan Oord ACZ Marine Contractors b.v. Argentina Branch, Buenos Aires, ArgentinaBallast Ham Dredging do Brazil Ltda., Rio de Janeiro, BrazilDragamex S.A. de C.V., Coatzacoalcos, MexicoDredging International Mexico S.A. de C.V., Veracruz, MexicoMexicana de Dragados S.A. de C.V., Mexico City, MexicoCoastal and Inland Marine Services Inc., Bethania, PanamaStuyvesant Dredging Company, Louisiana, U.S.A.Boskalis International Uruguay S.A., Montevideo, UruguayDravensa C.A., Caracas, VenezuelaDredging International N.V. - Sucursal Venezuela, Caracas, Venezuela

Terra et Aqua is published quarterly by the IADC, The International Association of

Dredging Companies. The journal is available on request to individuals or organisations

with a professional interest in dredging and maritime infrastructure projects including

the development of ports and waterways, coastal protection, land reclamation,

offshore works, environmental remediation and habitat restoration. The name Terra et

Aqua is a registered trademark.

© 2007 IADC, The Netherlands

All rights reserved. Electronic storage, reprinting or abstracting of the contents is

allowed for non-commercial purposes with permission of the publisher.

ISSN 0376-6411

Typesetting and printing by Opmeer Drukkerij bv, The Hague, The Netherlands.

Contents 1

EDITORIAL 2

ENVIRONMENTAL MONITORING AND MANAGEMENT OF 3RECLAMATIONS WORKS CLOSE TO SENSITIVE HABITATSSTÉPHANIE M. DOORN-GROENFeedback monitoring provides quantifiable compliance targets thus allowing reclamation activities to proceed in close proximity to Singapore’s most import marine habitats.

PLANNING FOR THE FUTURE – GROUND IMPROVEMENT TRIALS 19AT THE PORT OF BRISBANEPETER BOYLE, JAY AMERATUNGA, CYNTHIA DE BOK AND BILL TRANBERGHistorically the consolidation of reclaimed land takes about 10 years, but with the urgent need for land expansion, new ground improvement techniquesare being tested to shorten the timeframe for preparing the land for use.

PANAMA CANAL ATLANTIC ENTRANCE EXPANSION PROJECT 27JAN NECKEBROECKThe challenge of widening and deepening the Canal without obstructingthe heavy vessel traffic in transit was met by using state-of-the-art, large capacity, self-propelled dredging equipment.

BOOKS/PERIODICALS REVIEWED 32Useless Arithmetic by Pilkey and Pilkey-Jarvis challenges conventional wisdom about the accuracy of predicative modeling.

SEMINARS/CONFERENCES/EVENTS 33Autumn conferences in Bulgaria, Antwerp, London and Rotterdam are scheduled as well as a Call for Papers for CEDA Dredging Days 2008 in Belgium.

CONTENTS

TERRAETAQUA

EDITORIAL

According to the Merriam-Webster Online dictionary, innovation means driven by “the introduction of something new; a new idea, method or device”. Innovation is the major source for new productsand new technologies. In other words, the major source for progress.

We view the activities of the dredging industry as drivers of progress; but constructing new land, building coastal defence systems and maintaining and expanding our ports are not without impacts.To achieve lasting progress in maritime construction requires innovations that balance the economyand the ecology.

For the international dredging and maritime construction industry, innovation is an ever-present andcontinuous process. It is the driver that keeps the industry at the top of its game. Innovation meansconstantly striving to be better, to find more cost-effective dredging methods, more efficient shipsand technologies, improved means of site investigations, and advanced environmental impactassessments. In recent decades, numerous innovations in the modern dredging industry have made it possible to reshape many regions and coastal areas.

In this issue of Terra three large infrastructure projects in very different areas of the world arerepresented: Singapore; Brisbane, Australia; and the Panama Canal. Each of these projects ischaracterised by the significance of seeking, and finding, new ways to serve economic andenvironmental interests alike.

In Singapore’s sensitive coral reef habitats, traditional methods for environmental management werenot sufficient. This IADC Award-winning paper from WODCON XVIII explains the intricacies of anenvironmental monitoring and management system that helps dredgers comply with the strictestenvironmental standards and ensure the preservation of the priceless coral reefs.In Australia, the need for new land is outpacing the ability to create it. The Port of Brisbane Corporation,therefore, has started trials to find innovative ways to hasten the preparation of land reclamations sothat the land can be utilised more quickly. The aim is to cut the time needed for the new land toconsolidate from 10 years to 5 years.And in this post-Panamax age, widening and deepening the Panama Canal – one of the essentialarteries for world trade – has become a priority. Thanks to the unique capabilities of the moderninternational fleet of large, sophisticated dredging vessels, some of this work has already beensuccessfully completed at an accelerated rate and without disturbance or interruption of vesselstransiting the Canal.

None of these projects would have been possible without the commitment of the dredging industryand its suppliers to research and development. The quest for innovation energizes the industry’sengineers, scientists and project managers to meet the daily challenges that come with maritimeconstruction. It also inspires them to look to the future and to seek long-term solutions for potentialchallenges. At the same time, these creative, innovative technologies provide clients and the public at large with the economic progress and the ecological sustainability they desire and deserve.

Robert van GelderPresident, IADC Board of Directors

2 Terra et Aqua | Number 108 | September 2007

ENVIRONMENTAL MONITORING ANDMANAGEMENT OF RECLAMATIONS WORKSCLOSE TO SENSITIVE HABITATS

STÉPHANIE M. DOORN-GROEN

ABSTRACT

Traditional methods for environmentalmanagement of marine reclamation worksclose to sensitive habitats have generallynot provided the level of control necessaryto ensure preservation of these habitats.Obtaining the level of control necessary toassure authorities and non-governmentalorganisations (NGOs) of compliance withenvironmental quality objectives, requiresquantifiable compliance targets coveringmultiple temporal and spatial scales.

Of equal importance to allow feedback ofmonitoring results into compliance targetsand work methods are effective and rapidresponse mechanisms. This article describesthe successful implementation ofcomprehensive Environmental Monitoringand Management Plans (EMMP), basedupon such feedback principles, which allowreclamation activities to proceed in closeproximity to Singapore’s most importantmarine habitats under third party scrutiny.

Specific focus is placed on describing themethods utilised to quantify compliancewith daily spill budget targets and howsuch targets and compliances are assessed.To improve reliability, the spill budgets take

into account specific habitat tolerance limitsfor varying magnitudes and durations ofsediment loading. Refinements to sedimentplume models were undertaken to enhancetheir ability to hindcast impacts from thecontractors’ complex reclamation schedules.Methods for segregation of impacts andassessment of cumulative impacts were alsointegrated into the hindcast procedures.Finally, the article describes the updating of tolerance limits and confirmation of spillbudgets via targeted habitat monitoring.

To date, the EMMPs have been able todocument compliance of the works to allpre-project environmental quality objectivesat a level of reliability that cannot be refutedby third parties. This has minimised thedevelopers’ and contractors’ exposure topublic complaints and liabilities associatedwith environmental impacts. The EMMPshave thus allowed the reclamation activitiesto proceed in an efficient manner, whilstensuring protection of the environment.

The author wishes to acknowledge theimportant contributions of Thomas M. Foster,

Regional Director Southeast Asia, DHI Water& Environment (S) Pte Ltd to this research.This paper was first presented at WODCONXVIII in June 2007 and was published in theconference Proceedings. It is reprinted herein a slightly revised version with permission.

INTRODUCTION

The tropical waters in Singapore provideexcellent conditions for marine life, owingto relatively constant tropical watertemperatures and frequent fresh oceanthrough flow from both the South ChinaSea and Melaka Straits. Coral, seagrass andmangrove habitats have been found to berelatively rich in Singapore. The diversity ofthe coral habitats in Singapore is confirmedby the fact that of the 106 coral generaexisting world wide (Veron et al. 2000), 55 genera are documented in Singaporewaters alone (Tun et al. 2004), compared to 13 genera found in the Caribbean. For seagrass habitats, 12 species out of 57known species are found in Singapore(Waycott et al. 2004), whereas 24 out of54 true and minor mangrove species havebeen found in Singapore so far (Thomlinson1999). These numbers document the highdiversity of marine habitats in a relatively

Above, For coral reef areas subject to direct impact,

coral relocation is undertaken prior to the start of

reclamations works.

Environmental Monitoring and Management of Reclamations Works Close to Sensitive Habitats 3


small environment as Singapore andemphasize the importance of marinehabitat conservation in Singapore.

Owing to the confined nature of Singaporewaters and the presence of a large numberof patch reefs, reclamation and associateddredging activities (in the following referredto generically as reclamation activities),often take place in very close proximity tocoral reefs and seagrass areas. In addition,increasing industrial development results in developments also occurring close tosensitive industrial water intakes.

Recognizing the value of these marinehabitat and industrial resources, Singaporehas established strict Environmental QualityObjectives (EQO) for marine constructionactivities. In order to document compliancewith these EQOs, pro-active EnvironmentalMonitoring and Management Plans (EMMP)based upon feedback monitoring principlesare required for marine construction activitiesto proceed, when these are in closeproximity to key environmental receptors.

Introduced in Europe in the 1990s andrefined during the EMMP works for theØresund Link between Denmark andSweden (Møller 2000) and Bali Turtle Island,Indonesia (Driscoll et al. 1997), feedbackEMMP provides the level of responsivenessand documentation necessary to assureboth authorities and other interest groupsthat the works meet the EQOs throughoutthe construction period.

Based upon the strict nature of the EQOs,EMMPs in Singapore are required toestablish compliance of the works acrossmultiple temporal and spatial scales:• Compliance assessment against daily

spill budget targets at the work area;• Real-time monitoring and compliance

assessment against response limits,particularly for intakes and reefs in close proximity to the work area;

• Compliance assessment against resultsof daily hindcast modelling compared to habitat tolerance limits throughoutthe potential impact area.

The feedback mechanism allows forupdating of the spill budget limits, response

limits and tolerance limits, based on theresults of sedimentation monitoring andhabitat monitoring. To ensure the accuracyof the entire system, the performance isconfirmed on a daily basis via controlmonitoring of sediment spill.

This article presents how the variouscomponents of the EMMP are established andexecuted, together with the refinementsnecessary to ensure a level of responsivenessappropriate to the importance of thereceptors.

BASIC COMPONENTS OF THE EMMP

The EMMP is the primary method of controlto ensure EQOs relating to marine habitatsand other environmental receptors are met.The EMMP is further a tool to:• detect any unexpected impacts at an

early stage, • establish the response necessary to

address such impacts, and • confirm that appropriate tolerance

limits have been adopted.

The feedback approach of the EMMP ispro-active. It links the results of detailednumerical hindcast models of the sedimentplumes resulting from reclamation activitieswith the results from online turbidity andcurrent sensors, daily spill measurementsand periodic habitat surveys, and comparesthese against the spill budget.

The spill budget is the maximum allowablespill (daily, weekly and fortnightly limits are set), which will still ensure (based onthe results of sediment plume forecastmodelling) that the EQOs are met. As environmental receptors, like corals,have a different tolerance againstsuspended sediment levels than for examplemangroves, individual tolerance limits aredefined for each environmental receptor.

The tolerance limits play an important rolethroughout the project, as the daily spillbudget is based on these individual limits.Both tolerance limits and spill budgets areevaluated and updated during the project,based on results of the habitat monitoringcampaigns.

The main components of Feedback EMMPs,as implemented in Singapore are:

i) Environmental BaselineFeedback variables are identified,instrumented and monitored for astatistically significant period prior to construction, which is typically in the order of 3 to 6 months. Variables monitored include all key environmental receptors such as corals reefs, seagrass beds,mangroves, turbidity, water quality,currents and sedimentation. This phase also includes theconfirmation of the environmentalquality objectives for the project and environmental tolerance limits. If compensatory works are required, such as coral relocation from directimpact areas, this is also undertaken at this stage of the EMMP.

ii) Elaboration of work plansThe appointed reclamation contractorelaborates a work plan, specifying thedistribution of the work in time andspace, procedures and equipment.

iii) Assessment of work plansThe effect of performing the work planon the environment is assessed throughthe use of numerical sediment plumeforecast modelling.

vi) Revision of work plans If the forecasted impact resulting fromimplementation of the work plan leadsto unacceptable effects, i.e. violation of EQOs, the work plan is revised andreassessed. Once the work plan isfinalised a final EMMP specificationdocument is drawn up that specifies the detailed execution, response andmanagement process for the EMMP. In particular, the final EMMP specificationincludes a spill budget (for each phaseof the reclamation), which is the limitingamount of spill that will still result in theEQOs being met and against which theday-to-day control of the reclamationwork can be assessed.

v) Construction phaseReclamation commences.

vi) Compliance monitoringMonitoring of daily compliance variablesagainst the pre-determined sedimentspill limits (spill budget). If dailycompliance limits are violated, mitigationactions are established and implemented.If no violations of limits occur, reclamationwork and daily monitoring continue.Compliance monitoring is reported on a daily basis and to ensure the level ofresponsiveness, reporting is required amaximum of 45 hours in arrears of anyreclamation activity.

vii) Control monitoringMonitoring of real time measurementsand comparison to response limits, such as online turbidity data or weeklysedimentation data. If no violations oflimits occur, work and control monitoringcontinue. Control monitoring is reportedto the time scale of the monitoringactivity (daily or weekly).

viii) Spill hindcastSpill hindcast documents the impact of the reclamation progress on theenvironment remote to the work site.The spill hindcast is based upon realizedproduction schedules, composition offill material and actual tide conditions.The assessment is made through theuse of numerical sediment plumehindcast modelling, with the hindcastupdated every day. Reporting of thehindcast is made a maximum of threedays in arrears of the actual progress ofthe reclamation works so that remoteimpacts are captured prior to thembecoming significant.

ix) Habitat monitoringMonitoring of biological habitatfeedback variables is performed to anappropriate time schedule for theanticipated response rates. This is typicallyonce every three months for coral reefs,seagrass beds and mangrove areas.

x) Evaluation of construction phaseBased on the results of the biologicalmonitoring of feedback variables andthe results of the numerical spillhindcast modelling of the realizedconstruction process, the temporal and

IADC AWARD 2007

PRESENTED AT WODCON XVIII,

ORLANDO, FLORIDA, USA

MAY 27-JUNE 1, 2007

An IADC Best Paper Award was presented to

Stéphanie M. Doorn-Groen, Manager Engineering

Services at DHI Singapore, who has been based

in Southeast Asia since May 2002 and joined DHI

Singapore in January 2004. She graduated in

2000 with a BSc (Civil Engineering) from the

Polytechnic The Hague, the Netherlands and in

2002 with a MSc (Civil Engineering Management

& Geotechnology) from South Bank University

London, UK. Her previous experience was as a

geotechnical adviser for Fugro Onshore

Geotechnical bv, as a superintendent and

technical employee for the dredging company

Van Oord bv and for Municipal Works, Ports,

Design & Construct, Rotterdam, the Netherlands.

Each year at selected conferences, the


grants awards for the best papers written by

younger authors. In each case the Conference

Paper Committee is asked to recommend a

prizewinner whose paper makes a significant

contribution to the literature on dredging and

related fields. The purpose of the IADC Award is

“to stimulate the promotion of new ideas and

encourage younger men and women in the

dredging industry”. The winner of an IADC Award

receives Euros 1000 and a certificate of

recognition and the paper may then be published

in Terra et Aqua.


spatial impacts of the constructionphase are assessed. If EQOs are violated,mitigation actions are established,assessed and undertaken. On the basisof the realized impacts, environmentalcriteria (tolerance limits) and compliancecriteria (spill budgets) for the nextconstruction phase are updated (thefeedback loop).

xi) Next construction phaseThe construction and monitoring processreturns to task v) for each major stageof the reclamation and the process isrepeated until reclamation is complete.

xii) Completion of constructionAn environmental audit is produced atthe end of the construction period asformal documentation of the impactsrealised during the construction phase.This is based upon the result of thecompliance, control, habitat and supportmonitoring together with the results ofthe hindcast modelling of impacts. Theenvironmental audit is based on a finalhabitat survey usually carried out threemonths after the end of construction.

The main advantages of this approach toEMMPs are:• Compliance measurements are targeted

in the sediment plume resulting fromdredging and reclamation activities, as close as possible to the source of spill at the given time of measurement.This provides a much more accuratemeasurement of suspended sedimentspill than can be achieved via fixedturbidity sensor stations, which often lie outside the sediment plume forindividual dredging or reclamationoperations.

• Numerical sediment plume forecastmodels allow assessment of changes to the spill budget for variations incomplex reclamation schedules andvarying tide and ocean currentconditions, thereby ensuring the spillbudget is the most appropriate for thegiven stage of the works given thespecific equipment to be utilized andtiming of the activity.

• The hindcast model documents thespatial distribution of impacts at all

Stéphanie M. Doorn-Groen receiving an IADC

Award for young authors from Constantijn

Dolmans, Secretary General of IADC.


the receptor sites in the vicinity of thereclamation site with far broader spatialscale and finer temporal resolution thancan be achieved via habitat monitoringin isolation.

• The hindcast model keeps a runningbalance of the cumulative sedimentationimpact levels based on actual productionprovided by the reclamation contractor.Increasing levels of sedimentation can bedetected at an early stage and mitigatingmeasures can be applied, if necessary.

• The combined use of daily spillcompliance monitoring, controlmonitoring and hindcast modelling allowsthe EMMP to respond rapidly and reliablyto different temporal impact scales (fromfor example, short term exceedencesresulting from, for example, unexpectedevents, to long-term trends resultingfrom, for example, deterioration in thequality of fill material).

• The feedback loop ensures that tolerancelimits and resultant spill budgets areconsistent with the specific sensitivity of the environmental receptors in theimpact area.

ENVIRONMENTAL QUALITY OBJECTIVES

In order to set EQOs for a project, it isessential that a classification scale is adoptedto define the scale of impacts that may beallowed at a given environmental receptor.The following scale of impact classificationshas been adopted for several projects inSingapore:• No impact: Changes are significantly

below physical detection level andbelow the reliability of numericalmodels, so that no change to thequality or functionality of the receptorwill occur.

• Slight impact: Changes can be resolvedby numerical sediment plume models,but are difficult to detect in the field asthey are associated with changes thatcause stress, not mortality, to marineecosystems. Slight impacts may berecoverable once the stress factor hasbeen removed.

• Minor impact: Changes can be resolvedby the numerical models and are likelyto be detected in the field as localized

mortalities, but to a spatial scale that is unlikely to have any secondaryconsequences.

• Moderate impact: Changes can beresolved by the numerical models and aredetectable in the field. Moderate impactsare expected to be locally significant.

• Major impact: Changes are detectablein the field and are likely to be relatedto complete habitat loss. Major impactsare likely to have secondary influenceson other ecosystems.

The task of defining EQOs rests with theauthorities and is made on an area by area,habitat by habitat basis. For reclamationprojects in Singapore, “Slight Impact” istypically allowed in the area immediatelyadjacent to (within 500 m) of the workarea, whilst “No Impact” is required for allenvironmental receptors remote from thework area. For coral reef areas subject todirect impact (i.e. under the reclamationprofile), it is presently common practice inSingapore to compensate for the habitatloss by undertaking a coral relocationexercise prior to start of reclamation works.

TOLERANCE LIMITS ANDENVIRONMENTAL QUALITY OBJECTIVES

The linkage between project EQOs and spill budget depends on the method ofreclamation and on the tolerance limits ofthe various environmental receptors, whichin turn depends upon the pre-projectexternal stress levels on the ecosystem. In Singapore, initial tolerance limits for the most sensitive marine habitats (coralsand seagrass) have been established basedupon extensive literature review and DHI’sexperience from similar projects in theSouth East Asia region.

These tolerance limits have then beenrefined over the course of several projectsin Singapore, based upon the results ofproject specific habitat monitoring.Presently, these limits, as presented below,are believed to be the most relevant set oftolerance data available for coral reefs andseagrass beds subject to incrementalreclamation impacts on top of elevatedexternal (non-project related) stress levels.

Coral tolerance to suspendedsedimentsIn simplified terms, as hard corals aredependent on symbiotic photosynthesizingzooxanthellae for their nutrient supply andsurvival, they are sensitive to increasedturbidity levels as the reduction in lightpenetration through the water columnadversely affects the photosynthesisprocess. Perhaps more seriously, elevatedsedimentation levels can clog the corals’respiratory and feeding system, whilst alsocausing complete light extinction to theimpacted area of the colony.

The level of sensitivity depends on thecharacteristics of the corals, with platecorals like Pachyseris sp. proving the mostsensitive to increased sedimentation andleast sensitive to reduction in lightpenetration. Conversely, branching coralssuch as Acropora sp. show the oppositesensitivity trend. Clearly, other impacts suchas degradation of substrate impactingattachment of coralline larvae are alsoimportant to the overall impact levelexperienced by a reef. However, the presentstate of the art cannot quantify suchdetails, which are therefore captured viathe habitat monitoring component of theEMMP rather than via the tolerance limits.Background levels vary from region toregion and are very site specific. Researchfrom the Barrier Reef (Harriot et al. 1988)indicates that these corals are tolerant tolevels of suspended sediments up to 4 mg/l(absolute concentration). However, studiesin Hong Kong have shown tolerance levelsup to 10 mg/l. Extensive monitoring datafrom multiple projects in Singapore (wherechanges in reef health, measured as afunction of live hard coral cover anddiversity, has been compared to measuredand predicted suspended sediment andsedimentation levels), has allowed thedevelopment of an coral tolerance matrixfor excess (above background) suspendedsediment concentrations, see Table I.

This table is found to be applicable for theelevated background turbidity levels commonin Singapore and the typical Singapore reefmorphology, which is dominated by themore resilient massive corals and platecorals, as shown in Figure 1.

Coral tolerance to sedimentationCoral sensitivities to sedimentation aredetermined largely by the particle-trappingproperties of the colony and the ability ofindividual polyps to reject settled materials(Figure 2). Horizontal plate-like colonies andmassive growth forms present large stablesurfaces for the interception and retentionof settling solids. Conversely, vertical platesand upright branching forms are less likelyto retain sediments.

A threshold (absolute) value of 0.1 kg/m2/dayhas previously been adopted as the criticalvalue for corals in Environmental ImpactAssessments in Hong Kong. However,monitoring data from Singapore indicatesthat an incremental value of 0.05 kg/m2/dayis more appropriate for the type of coralhabitats and existing stress levels in Singaporewaters. Based on these Singapore data sets,the tolerance limits presented in Table II arefound to be relevant for sedimentationimpact on corals for reefs with naturally highbackground sedimentation levels, assuming a net deposition density of 400 kg/m3.

Seagrass tolerance to suspendedsedimentsProductivity of seagrass can be limited owingto reduced light penetration resulting fromthe presence of algal blooms and suspendedsediments. Seagrass requirements for lightpenetration have been well described bymultiple authors, with the habitat beingconfined to water depths where light levelsare above 10% to 15% of surfaceirradiance. For the normal tidal rangeexperienced in the Singapore area, these

figures concur well with observations withinSingapore waters, which indicates thatseagrass are generally limited to seabedareas shallower than –1 m CD. At low tide,many seagrass beds in the Singapore area

are exposed (Figure 3), indicating a possibleadaptation to, and higher tolerance to ahigh level of excess suspended sediments.For deeper beds, the tolerance is lower, butgiven the natural background variability in

Figure 1. Typical coral habitats in Singapore.

Table I. Impact severity matrix for suspended sediments on corals inenvironments with high background concentrations

Severity Definition (excess concentration)No Impact Excess Suspended Sediment Concentration > 5 mg/l

for less than 5% of the time

Slight Impact Excess Suspended Sediment Concentration > 5 mg/l


Excess Suspended Sediment Concentration > 10 mg/l


Minor Impact Excess Suspended Sediment Concentration > 5 mg/l

for more than 20% of the time



Moderate Impact Excess Suspended Sediment Concentration > 10 mg/l




Major Impact Excess Suspended Sediment Concentration > 25 mg/l




Table II. Impact severity matrix for sedimentation impact on corals

Severity Definition (excess sedimentation)

No Impact Sedimentation < 0.05 kg/m2/day (<1.7 mm/14 day)

Slight Impact Sedimentation < 0.1 kg/m2/day (<3.5 mm/14 day)

Minor Impact Sedimentation < 0.2 kg/m2/day (<7.0 mm/14 day)

Moderate Impact Sedimentation < 0.5 kg/m2/day (<17.5 mm/14 day)

Major Impact Sedimentation > 0.5 kg/m2/day (>17.5 mm/14 day)

suspended sediment load in the Singaporearea, it is reasonable to assume that theouter limits of the seagrass are welladapted (in terms of water depth) to short-term fluctuations in the backgroundconcentration of 5 to 10 mg/l, such thatexcess loadings higher than 5 mg/l will berequired to stimulate a noticeable habitatchange. These findings, coupled withmonitoring experience from the SE Asiaregion, result in the proposed impactseverity matrix presented in Table III.

Seagrass tolerance to sedimentationThe growth rates of seagrass are high.Growth in the order of 1 to 2 cm per dayhas been recorded for example forThalassia sp. (Durate et al. 1999) whilstgrowth rates in the order of 0.6 cm per dayhave been recorded for Enhalus sp. in Malaysia.Therefore, the short-term survival ofseagrass beds, which depends on anaerobicperformance, will only be impacted in thecase of very high sedimentation rates. Suchcritical sedimentation rates will normallyonly occur very close to a reclamation site.Based on experience in the SE Asia region,the following impact severity matrix ispresented for sedimentation impact onseagrass (see Table IV). Other impactsresulting from increased sedimentation,such as change in composition of substrate,are clearly also important to the overallimpact levels experienced by a seagrass bed,but such detailed impacts are difficult toquantify and are therefore captured via thehabitat monitoring component of the EMMP.

Figure 2. Sedimentation impact on corals and expulsion of sediment via mucus generation.

Table III. Impact severity matrix for suspended sediment impact on Seagrass in high background environments

Severity Definition (excess concentrations)No Impact Excess Suspended Sediment Concentration > 5 mg/l

for less than 20% of the timeSlight Impact Excess Suspended Sediment Concentration > 5 mg/l

for more than 20% of the timeExcess Suspended Sediment Concentration > 10 mg/l for less than 20% of the time

Minor Impact Excess Suspended Sediment Concentration > 25 mg/l for less than 5% of the time

Moderate Impact Excess Suspended Sediment Concentration > 25 mg/l for more than 20% of the timeExcess Suspended Sediment Concentration > 75 mg/l for less than 1% of the time

Major Impact Excess Suspended Sediment Concentration > 75mg/l for more than 20% of the time

Figure 3. Typical seagrass habitat

in Singapore.

Table IV. Impact severity matrix for sedimentation impact on Seagrass in highbackground environments

Severity Definition (Excess sedimentation)No Impact Sedimentation < 0.1 kg/m2/day (<0.25 mm/day)Slight Impact Sedimentation < 0.25 kg/m2/day (<0.63 mm/day)Minor Impact Sedimentation < 0.5 kg/m2/day (<1.25 mm/day)Moderate Impact Sedimentation < 1.0 kg/m2/day (<2.5 mm/day)Major Impact Sedimentation > 1.0 kg/m2/day (>2.5 mm/day)


Mangrove tolerance to suspendedsediments and sedimentationMangroves can be considered to be verytolerant to the range of suspendedsediment loads that may be generated from dredging and reclamation activities.Of the various mangrove species, thosewith pneumatophore root systems are themost sensitive to sedimentation (Thampanyaet al. 2002), but even mangroves withpneumatophore root systems are only likely to be stressed when prolongedsedimentation reach levels from 10 cm upto 30 cm. This level of sedimentation isunlikely to occur outside the work area,and mangroves are thus not considered assensitive receptors. Never-the-less, as EQOsare normally specified for mangrove areas,they are normally included in the habitatmonitoring campaigns for reclamationEMMP in Singapore. Figure 4 presents atypical mangrove habitat in Singapore area.

Visual impact and detection limitsIn the turbid environments that are foundaround Singapore, low concentrationsediment plumes in the surface of thewater column are generally not visible(based upon results of remote sensinganalysis) if the excess concentration abovebackground does not exceed 5 mg/l.A realistic measurable visual detection limitfor non-recreational areas (in the Singaporehigh background turbidity context) wouldbe a reoccurring plume present for 30-40 minutes per 12 hour daylight period,i.e. an exceedence of about 5% per day,whilst for recreation areas a limit of 2.5%exceedence proves to be appropriate.

Intake tolerance limits to suspendedsedimentsFor many industrial intakes the absolutetolerance limit to suspended sediments isnot known by the operators. In such cases,the most practical method for establishinga tolerance limit is to carry out statisticalanalysis on long-term background suspendedsediment data from the immediate area ofthe intake. It is then possible to carry out atest for no statistical change (at a confidencelimit agreed with the operator) for thevarious time scales of interest (daily, weekly,monthly and 6 monthly tests are normallyconsidered in Singapore).

DAILY COMPLIANCE MONITORING

Based on the EQOs, spill budgets aredefined for each stage of the reclamationworks. The spill budgets are updated aswork progresses and feedback informationconfirms their applicability or indicates arelaxation or tightening is warranted.

The contractor’s compliance to the daily spillbudget is assessed on a daily basis against dailyspill budget targets and on a weekly basisagainst weekly and fortnightly spill budgettargets. Typically, the fortnightly spill budget is60% of the daily spill budget, reflecting theability of most receptors to cope with higherlevels of stress if they are short-term or inter-mittent in nature. Daily compliance to spillbudget targets must be established within atime frame which will allow response beforeany non-compliance will pose a threat to theenvironment. Therefore, daily compliancemonitoring requires strict daily procedures fordata delivery from the contractor, to ensuredaily spill calculations, laboratory analysis dailycompliance analysis and reporting can becarried out in a timely manner.

On daily basis the contractor supplies:• Realised dredging volumes per dredger

for every single trip, including locationand method;

• Start and end time of dredging cycle,including delays;

• Realised reclamation volumes perdredger for every single trip, includinglocation and method;

• Start and end time of reclamation cycle,including delays;

• Representative sediment samples fromeach load to be analyzed for finecontents by an external laboratory.

In addition to the data provided by thecontractor, suspended sediment samplesare taken in the main plume discharge ofthe reclamation site (either as suspendedsediment samples (TSS) or sediment fluxmeasurements using acoustic backscattertechnology). The location and the time ofthe sampling reflect the reclamationactivities of the contractor and the samplesare analysed for TSS by an external laboratory.

This analysis provides a second method ofcontrol and serves as a validation for thespill calculation and performance of thenumerical hindcast models. Based upon thefines content of the fill and dredge materialand method of reclamation an empiricalestimate of the total spill is made, for eachreclamation/dredging operation over thepreceding 24 hr period. The resultant totalcan then be compared to the spill budget

Figure 4. Typical mangrove habitat in Singapore: Avicennia pneumatophore system (foreground) and

Rhizophora stilt root system (background).


on the level of compliance established forthe 24 hr period. A typical example is shownbelow for rainbowing operations.

Spill of fines leaving immediate dredgingarea = Load volume * fines % * 25%

Although it is recognised that the specificspill is dependent on many factors such asthe prevailing water depth and currentspeed, this simple empirical formula hasproved to be a reliable method forestimation of spill for sand placement inthe typical range of physical conditionsencountered in Singapore.

Validation of the spill calculation issubsequently provided by the TSS orsediment flux measurements in the plume.However, for the purpose of the dailycompliance monitoring a simple, yetreliable, empirical formulation is required to meet the reporting time scale.

Figure 5 presents a general flowchart of the complex daily operating proceduresrequired to establish compliance with spillbudget targets to a time frame which willallow response before any non-compliancewill pose a threat to the environment,which has been defined as a maximum of45 hrs in arrears of any activity on site.

Figure 6 presents an example of the dailyspill calculations over a period of fivemonths based on the empirical methodsdescribed above and validated by thecontrol sampling in the sediment plume.This figure indicates that the daily spillbudget was exceeded for a period in April. Mitigating measures were introducedand subsequently the spill budget wasachieved for the remainder of thereclamation work.

Figure 5. Daily operating procedure for

daily compliance monitoring.

Figure 6. Spill results from

reclamation operations.


DAILY HINDCAST MODELLING

Based upon the information provided bythe contractor in terms of time and locationof activities and the calculated spill, dailyspill hindcast simulations are run in order toestablish the temporal and spatial impactsof the sediment plumes released from thework area.

Hydrodynamic model setup andperformanceThe daily hindcast modelling is based uponDHI’s extensively verified 675/225/75/25 mMIKE 21 nested grid hydrodynamic modelof the Singapore Straits, which wasdeveloped in 2001 and is being continuouslyrefined on the basis of daily real time currentmeasurements.

Figure 7 shows the overall regional modelgrid coverage utilised for EMMP projects inthe Singapore area, whilst Figure 8 presentsan example of the model performancewhich meets relevant international standardssuch as UK Foundation for Water ResearchPublication Ref FR0374 “A framework formarine and estuarine model specification inthe UK”. The 25 m Model resolution isadopted in the specific area of reclamationto ensure all relevant local hydrodynamicfactors, which may affect the plumetransport and dispersion are resolved.

Bathymetric survey data are taken directlyfrom digital navigation charts,supplemented by project specific surveydata, which is updated on a weekly basisfor reclamation progress in the specificproject areas.

Figure 7. DHI’s Singapore Straits regional

675 m grid model with nested

intermediate 225 m grid and local

75 m grid sub-domain models.

Figure 8. Example performance of DHI’s Singapore

Straits current forecast model. RMS error on current

speed at presented validation point = 0.09 m/s.


Sediment plume model set-up andperformanceCalibration and validation of DHI’s sedimentplume hindcast model for Singapore watershas been carried out over the course ofseveral projects. A typical example of themodel performance is provided in Figure 9.Throughout the course of the EMMP, theperformance of the model is verified on adaily basis, either by direct TSS measurementswithin the sediment plume or via sedimentflux transects through the plume.

Critical shear stress for erosion anddepositionA vital factor to the performance of the modelin terms of documenting impacts on coral reefhabitats is the parameterisation of the criticalshear stress for erosion and deposition overthe reef areas. The complex morphology ofcoral reefs on both micro and macro scales,leads to an increased tendency for depositionto occur and a reduced tendency for re-suspension. Extensive testing andcomparison to sediment trap data collectedon a weekly basis has been undertaken,leading to the following conclusionsconcerning average critical shear stressparameters for deposition and re-suspensionof fines over coral reef areas in Singapore:

• Critical shear stress for deposition offine material over coral reef: 0.6 N/m2

• Critical shear stress for re-suspension ofinitial deposits over coral reef: 1.5 N/m2

Figure 10 presents the example maps ofcritical shear stress in South-WestSingapore, whilst Table V presents anexample of model performance againstmeasured sediment trap data.

Location survey vessel

Water samples were taken

TSS results:

Point 15: 2.5 mg/l

Point 16: 12.0 mg/l

Point 17: 40.0 mg/l

Point 18: 6.0 mg/l

Point 19: 1.8 mg/l

Figure 9. Location and magnitude of the sediment plume predicted by DHI’s hindcast model

and the location of the survey vessel during plume transects.

Table V. Example of model performance measured against reef sedimentation data

Figure 10. Maps of critical shear stress for erosion (left) and deposition (right) covering

SW Singapore for sediment released from dredging and reclamation operations.

Measured incrementalsedimentationKg/m2/day

0.020.04

Predicted incrementalsedimentation withoutadjustment of critical shear stress parameters

< 0.01< 0.01

Predicted incrementalsedimentation withadjustment of critical shear stress parameters

0.040.04


Sediment settling velocity In order to reliably simulate the transportand fate of the fine material released fromdredging and reclamation activities, it alsoproves necessary to divide the sedimentspill into a number of sediment fractions.After testing of various options, 6 fractions(3 for reclamation fill and 3 for dredgematerial) have been found to provide agenerally consistent compromise betweenmodel reliability and computational time,which is critical to the reporting schedule.

In order to establish the characteristics ofthe 6 sediment fractions, fall velocitytesting of the fine material present in thereclamation and dredge material is carriedout on a regular basis via Owen tube tests.Fall velocity characteristics are typicallyupdated on a monthly basis (separately forreclamation fill and dredged material), orwhen the daily control measurements inthe sediment plume indicate a necessity forupdating. An example of the Owen tubetest results is provided in Figure 11.

Execution of daily hindcastBased on the contractor’s activity informationand calculated spill, the numerical spillhindcast is carried out on a daily basis forthe actual reclamation operations. The result

of the daily EMMP hindcast model arevalidated against the daily control samplestaken in the sediment plumes originatingfrom the reclamation.

The daily hindcast is processed to allowdirect comparison to the EQOs with thefollowing key outputs:• Time series and tabulation of excess

suspended sediment concentration atthe various environmental receptors;

• Maps of exceedences of 5, 10 and 25 mg/l excess concentration;

• Animations of concentration maps.

UPDATING OF TOLERANCE LIMITS ANDSPILL BUDGET

As the spill budget is dependent on thetolerance limits of the various environmentalreceptors, it is critical that the reliability ofthese limits is confirmed at an early stageof the construction works, with continuousrefinement carried out throughout theconstruction period. The tolerance limits areconfirmed (or refined) based upon theresults of quarterly habitat monitoring ofkey environmental indicators compared tothe results of the sediment plume hindcastand sedimentation monitoring.

Habitat monitoringQuarterly control habitat monitoring surveysare carried out to establish the status of thevarious marine habitats near the developmentsite. The choice of survey locations is basedupon three criteria:• Importance and/or sensitivity of the

habitat;• Expected level of impact (based upon

the sediment plume forecast); and• Control stations outside the potential

impact area (based upon the sedimentplume forecast).

For each survey station key indicators areidentified and the survey sites laid out tofacilitate exact replicate surveys.

Coral habitat monitoringCoral surveys are primarily carried out usingthe Line Intercept Transect (LIT) method, asshown in Figure 12, which is recommendedby the Global Coral Reef Monitoring Network(English et al. 1997, Hill et al. 2004) forquantification of the percentage cover ofreef building corals, coral diversity, as wellas other benthic life forms. The LITmethodology, which provides a goodmethod for identification of mortalities oflarger reef areas, is supplemented by exactrepeat surveys of selected individual colonies,

Fraction 1 60% contribution

Representative fall velocity v = 0.00075 m/s

Coarse fines: settles quickly outside the work

area



Medium fines: can be transported large

distances during spring tide, prime case of

remote sedimentation



Fine fines: regularly transported large

distances, generally will not settle out,

contributing to suspended sediment impacts

Figure 11. Example sediment fall velocity distribution from Owen Tube test of fine material content of reclamation fill.

which is required to establish changes instress levels or partial mortalities of colonieslying off the transect line.

Example results from a repeat LIT surveyclose to the reclamation site at stationCR07 are presented in Table VI. The LITsurveys indicate no significant change inreef characteristics as illustrated by the plotin Figure 13.

For the exact repeat colony monitoring atthe same site, 50% of the colonies showedsome form of improvement in life formcharacteristics. 30% showed no changeand 2 colonies (20%) were noted to havedeclined as a result of physical damage notdirectly attributable to the reclamation works.

The sediment loading from the reclamationworks at this site over the monitoringperiod is tabulated in Table VII. Comparisonwith the coral tolerance limits presented in Table I and Table II indicates that thesediment loading falls in the No Impactcategory. This is consistent with therecoded LIT and exact repeat resultsconfirming, in this case, the applicability ofthe tolerance limits (at the No Impact level).Tolerance limits were therefore not updatedand spill budget limits for the period afterAugust 2006 were not adjusted.

Seagrass monitoringParameters used to assess the health of theseagrass areas include seagrass spatialdistribution and composition, seagrasspercent cover, seagrass diversity andevenness, seagrass biomass, sediment leveland composition.

Measures Analysis of Variance on Ranks,which is commonly used for comparisonbetween two datasets, is used for thestatistical analysis of sediment level andseagrass cover for comparison of the

baseline and repeat surveys. Figure 14 showsan example from a seagrass bed close to thereclamation site. The mean seagrass coverdocuments a general increase between thebaseline and the first Repeat Survey, but adecrease of approximately 20% documentedbetween the first and second repeat.

The corresponding sediment loading fromthe reclamation works at this site over themonitoring period is tabulated in Table VIII.This indicates the seagrass bed lie in theNo-Impact zone, though a moderate decrease

Figure 12. LIT Coral habitat survey in Singapore.

Table VI. Comparison of mean percent cover and standard deviationfor the major benthic categories at CR07

Baseline Repeat Survey 1 Repeat Survey 2Major Category August-05 May-06 August-06

Mean Cover (%) STDEV Mean Cover (%) STDEV Mean Cover (%) STDEVHard Coral 24.66 8.73 26.87 6.95 26.61 8.45Dead Coral 0.28 0.31 0.38 0.53 1.01 0.78Soft Coral 1.34 1.46 0.86 0.58 0.75 0.40Sponge 2.55 2.19 3.84 2.19 3.66 2.39Other Fauna 16.13 4.35 14.10 8.28 13.44 9.46Algae 19.93 8.01 27.87 8.76 30.36 12.86Rubble 32.72 16.21 21.86 8.62 22.02 9.51Rock 0.00 0.00 0.00 0.00 0.00 0.00Silt 0.00 0.00 1.94 2.50 1.63 2.16Sand 2.39 1.76 2.28 1.61 0.52 0.83Other 0.00 0.00 0.00 0.00 0.00 0.00



in cover was identified by the habitatmonitoring. In this case the hindcastmodels are conclusive in confirming thatthere is no direct flow of sediment from the reclamation area to this seagrass site,such that it can be firmly concluded thatthe decrease in seagrass cover is notattributable to the reclamation works.Tolerance limits were therefore not updatedand spill budget limits for the period afterAugust 2006 were not adjusted. The abilityto isolate impacts from a developmentproject from other third part or regionalimpacts is a major advantage of the feedbackEMMP system adopted in Singapore.

Sedimentation monitoring Sediment traps are deployed on the reefcrest, close to the LIT monitoring sites.These measurements documentsedimentation levels along the reef area,which is used in part to validate the resultsof the sediment plume hindcast models(incremental sedimentation abovebackground values) and in part to confirmtolerance limits. Sediment traps function asa measuring device for sedimentation onthe reef area and are deployed in threereplicates; each consisting of threecylindrical small tubes attached together.The theory and dimension of the sedimenttrap follows those recommended in theSurvey Manual for Tropical Marine Resources(English et al, 1997). See Figure 15 for animpression of the sediment traps deployed.

To function reliably in the high sedimentationenvironment present in Singapore, sedimenttraps are recovered every fortnight. As aresult of the large number of trapsdeployed in Singapore, ease of underwaterservice is important. This has lead DHI todevelop a single point of attachmentsystem that is operated by the single Allenscrew seen in Figure 15. This systemreduces the underwater service time byapproximately 50%, improves the reliabilityof the data by reducing sediment lossduring recovery and also reducesexpenditures associated with cable ties andother consumables by approximately 50%.

Table VII. Summary of percentage exceedence of suspended sediment and sedimentation loading over the coral reef monitoring site CR07 presented in Table VI

DateMarch April May June July August2006 2006 2006 2006 2006 2006

% Exceedence 5 mg/l < 5% < 5% < 5% < 5% < 5% < 5%Nett sedimentation kg/m2/day < 0.05 < 0.05 < 0.05 < 0.05 < 0.05 < 0.05

Figure 13. Changes in the mean percentage cover of

the major benthic categories.

Table VIII. Summary of sedimentation loading over the seagrass monitoringsites presented in Figure 14

DateMarch April May June July August2006 2006 2006 2006 2006 2006

Nett sedimentation kg/m2/day < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1

Baseline (Sep 05)

Repeat 1 (May 06)

Repeat 2 (Aug 06)

Figure 14. Comparison of mean seagrass cover along transect CY03.


Figure 16 presents an example of theabsolute sedimentation rates close to thework area at the same reef monitoringpresented in Table VI. This shows anaverage declining sedimentation ratebetween 0.08~0.11 kg/m2/day afterbaseline. The results presented in the figureindicate that no sedimentation impact atstation CR07 during July and August fallswithin the No Impact limits. These resultsare consistent with the results of thesediment plume hindcast and habitatsurveys (see Table VI for details of change inlive coral cover at CR07) and fall within theEQOs for the project.

Online turbidity sensors Online turbidity sensors are deployed at keyenvironmental receptors (coral reefs andintakes) in close proximity to the reclamationarea in order to provide an initial responsemechanism to any transients in suspendedsediment concentrations and to providesupplementary validation data for thesediment plume hindcast models. The instruments are vertically secured to aplatform deployed on the seabed, and heldapproximately 1 metre above the seabed.Data recorded is transformed from NTU toTSS via site-specific validation curves, whichare updated on a weekly basis based onmeasurements taken during instrumentservicing. The data is transmitted to a Data Information System that is used todisseminate all EMMP related data to theauthorities and contractors.

Figure 15. Three sedimentation traps are

fixed at each site located on the reef slope

close to the coral LIT sites. The height of the

trap from the reef surface to the opening is

35 cm. The sediment traps are held vertically

by angle-bars hammered deep into the

ground in an area of dead coral.

The actual dimension of the sediment trap is:

height 15 cm and Ø 5 cm.

Baseline

10 Jul ‘06

08 Aug ‘06

Average Sedimentation

CR07

Av

era

ge

Se

dim

en

tati

on

Ra

te [

kg

/m2/d

ay

]

Figure 16. Average sedimentation

rates at station CR07.

Figure 17. Left: deployed YSI turbidity sensor. Right: Time series of turbidity measurements.


Figure 17 presents a typical picture of theonline sensor and an example of meanturbidity levels. The increase in turbiditylevels observed in this example above thebaseline mean results from sensor fouling,which is a significant problem in Singaporewaters owing to high rates of algaegrowth, despite automatic sensor cleaningand weekly equipment service.

As the turbidity measurements provide onlya second level of EMMP response thereliability of the overall EMMP is notinfluenced by this fouling problem, whichwould otherwise be critical to managementplans reliant purely on static monitoring.

Other online instrumentation used forcontrol monitoring include, for example, noise meters (Figure 18) and AcousticDoppler Current Profilers (ADCP) (Figure 19).Noise meters are generally deployed atreceptor sites (residential buildings and/orwork sites) to document noise levels fromthe construction. ADCPs are deployed on the seabed for current and wavemeasurements.

CONCLUSION

The feedback approach to the EnvironmentalMonitoring and Management of reclamationworks summarised in Figure 20, which hasbeen adopted in Singapore, provides apractical and reliable method for the pro-active management of potentialenvironmental impacts resulting fromreclamation works.

The responsiveness of the system allowsunexpected impacts to be mitigated priorto them becoming a serious threat to theenvironment. Importantly, the level ofdocumentation provided ensures thatdevelopers and contractors are not exposedto unwarranted claims concerningenvironmental degradation as the EMMPapproach allows full segregation of projectimpacts from other third party disturbances.

In order to obtain the level of reliability andresponsiveness required to meet strict EQOsrelating to marine habitats and otherenvironmental receptors in Singapore, severalenhancements to various components of

the EMMP have had to be realised. Theseinclude empirical methods for estimation ofspill based upon sediment characteristicsand type of operation, adapting sedimentplume models to cater for complex dredgingand reclamation schedules, plus specificadjustment of settling and re-suspensioncharacteristics to cater for the complexitiesof reef morphology.

The performance of the feedback EMMP interms of meeting EQOs has been verifiedby habitat monitoring which also confirmadopted tolerance limits for corals andseagrass in high background suspendedsediment and sedimentation environmentssuch as those encountered in Singapore.

The EMMP techniques presented here havealso been successfully adopted for theenvironmental management of otherdredging and reclamation projects in theregion, including Bintulu and Kota Kinabalu,Malaysia and previously mentioned Bali TurtleIsland, Indonesia. The EMMP techniques arethus becoming accepted best practicemethodologies in the South East Asia Region.

Figure 18. A noise meter, built into a switch box. Figure 19. An Acoustic Doppler Current Profiler mounted on a stainless steel frame and about to be

deployed on the seabed.


REFERENCES

Duarte, C.M. & Chiscano, C.L. (1999) Seagrass

biomass and production: A reassessment.

Aquatic Botany, Vol. 65, 159-174.

Driscoll, A.M., Foster, T., Rand, P. and Tateishi, Y.

(1997). Environmental Modelling and

Management of Marine Construction Works in

Tropical Environments, 2nd ASIAN and Australian

Ports and Harbours Conference organised by

the Eastern Dredging Association, Vietnam.

English, S., Wilkinson, C. and Baker, V. (1997).

Survey Manual for Tropical Marine Resources

(2nd Edition), ASEAN-Australia Marine Science

Project: Living Coastal Resources. Australian

Institute of Marine Science, Townsville.

Harriott, V.J. and Fisk, D.A, (1988). Accelerated

regeneration of hard corals: a manual for

coral reef users and managers. Technical

memorandum GBRMPA-TM-16. Great Barrier

Reef Marine Park Authority, Townsville. 42 pp.

Hill, J. and C. Wilkinson (2004). Methods for

Ecological Monitoring of Coral Reefs. Australian

Institute of Marine Science, Townsville: 117 pp.

Møller J.S. (2000) Environmental Management of

the Oresund Bridge, Littoral 2000, Nice.

Thampanya, U., Vermaat, J.E., Terrados, J. (2002).

The effect of increasing sediment accretion on

the seedlings of three common Thai mangrove

species. Aquatic Botany 74, pp. 315-325.

Tomlinson, P.B. (1999) The botany of mangroves.

Cambridge University Press, United Kingdom.

Tun, K., Chou, L.M., Cabanban, A., Tuan, V.S.,

Reefs, Ph. Yeemin, Th., Suharsono, Sour, K., and

Lane, D. (2004). Chapter 9 Status of Coral Reefs,

Coral Reef Monitoring and Management in

Southeast Asia, 2004. In: Status of Coral Reefs

of the World, 2004. pp. 235-275.

Veron, J., Stafford-Smith, M. (2000) Corals of

the world, Volume I, II, III. Australian Institute

of Marine Science and CRR, QLD Pty. Ltd.

Waycott, M., McMahon, K., Mellors, J.,

Calladine, A., and Kleine, D. (2004). A guide to

Tropical Seagrasses of the Indo-West Pacific.

James Cook University, Townsville. 72 pp.

Figure 20. Summary of the prime components of feedback EMMP adopted in Singapore.

PLANNING FOR THE FUTURE – GROUND IMPROVEMENT TRIALS AT THE PORT OF BRISBANE

PETER BOYLE, JAY AMERATUNGA, CYNTHIA DE BOK AND BILL TRANBERG

ABSTRACT

The Port of Brisbane is located at themouth of the Brisbane River at FishermanIslands in Brisbane. In recent years, Port landhas seen rapid development as a result ofincreased trade growth. This growth in theSouth East Queensland region is expectedto continue for the next 25 years andbeyond. The expansion and development of future Port land will see the reclamationof about 235 ha of existing tidal flatsbounded by the FPE (Future Port Expansion)Seawall which was constructed to containthe reclamation. The reclamation will becarried out using channel maintenancedredging materials consisting of river mudscapped with sand, as has been the pastpractice. The seabed conditions, however,are significantly different in the seawall areabecause of the high water table, in-situcompressible clays over 30 metres deep andthe increased thickness of up to 7 to 9 metresof river muds to be deposited into thereclamation.

Whilst historically it has taken about 10 yearsfor reclaimed land to be available forcommercial use, it is currently anticipatedthat this timeline will have to reduce to lessthan 5 years to meet demand. Therefore

there is a critical need to accelerate theconsolidation of the reclaimed land astraditional surcharging used at the Port in thepast will not meet the future developmenttimelines. In order to optimise variousground improvement techniques and assesstheir suitability for the local conditions, the Port of Brisbane Corporation invitedexpressions of interest from specialistground improvement contractors for thedesign, supply and installation of groundimprovement techniques to carry out fullscale trials in the existing reclaimed land.Based on this process three internationallyknown contractors were appointed toconduct trials using wick drains and vacuumconsolidation. Relevant performance criteriawere established to assess performancethroughout the design and installationphases to enable a successful Trialist andsystem or systems to be selected next year tostart the broad-scale roll-out programme.

Port of Brisbane Corporation and CoffeyGeotechnics wish to acknowledge theprofessional and cooperative manner in whichthe three Trialists, namely, Van Oord, BoskalisAustralia and Austress Menard have gone

about their works during the design andinstallation phases. This paper was firstpresented at the Coasts & Ports 2007Conference, Melbourne, Australia in July 2007and is published here in an adapted versionwith permission.

INTRODUCTION

The Port of Brisbane is located at the mouthof the Brisbane River at Fisherman Islands.In recent years, the modern purpose-builtPort has seen rapid development as a resultof increased trade growth. This growth inthe South East Queensland region is expectedto continue for the next 25 years andbeyond. The expansion and development of future Port land is critical to ensure thatthe Port’s facilities can expand at a rate tomeet this growth. In 1999 the Portembarked on plans to investigate theexpansion of a 235 ha area immediately to the east of the existing reclaimed area.

In 2002, an Alliance Contract was formedbetween Port of Brisbane Corporation (PBC),geotechnical consultants Coffey Geotechnics(CG), coastal engineers WBM Oceanics, civil consultants Parsons Brinckerhoff andconstructor Leighton Contractors, to deliver

Above, Aerial view of the Port of Brisbane showing

the reclamation areas including the trial areas.

Planning for the Future – Ground Improvement Trials at The Port of Brisbane 19


the Future Port Expansion (FPE) Seawall, a 4.6 km long perimeter rockwall whichencloses the future expansion area. The Seawall construction, being the first stagein the expansion process, was completed inearly 2005 (Ameratunga et al. 2003 andAndrews et al. 2005). PBC has sinceengaged CG as their geotechnical advisorfor development of the reclamation areas.

CREATION OF NEW PORT LANDS

The Seawall allows for the containment ofthe progressive reclamation of about 235 haof existing sub-tidal flats. The reclamation willbe carried out using channel maintenance andberth dredging materials consisting of severalmetres of river mud capped off with sand.At the existing reclamation area (Figure 1)approximately 60 ha remains to bedeveloped (in 2006-2007), but is at a moreadvanced state of filling and capping thanthe FPE area. The subsurface conditions inthe seawall area and the existing reclama-tion area are significantly different from thedeveloped areas (Figure 1), because of thehigh water table, in-situ compressible claysover 30 m thick and the increased thickness

of up to 7 m to 9 m of river muds to bedeposited into the reclamation. Generallyconsolidation timings for these undevelopedareas are predicted to be well in excess of50 years if surcharging is the only treatmentemployed, as has been past practice.Settlements in the range of 2.5 m to 4 mare also forecast. Given the pressures ofcreating additional usable Port land in timeframes approximately half of those achievedin the past, a decision was taken that newtechniques to speed up the consolidationprocess need to be employed to meet theland development timings.

TREATMENTS TO SPEED UP LANDCREATION

Clearly, filling the reclamation areas withsand sourced from the Moreton Baychannels instead of dredged mud wouldreduce the total thickness of soft clay andtherefore minimise the impacts of filling thereclamation areas.

However, as PBC must maintain navigabledepths in its river channels and berths,some 500.000 m3 of mud on average is

dredged annually and must be disposed ofin an environmentally friendly mannerwithin the Port’s reclamation areas.

Substantial research and investigation by PBCand CG into local and overseas practices oftreatment of soft soil found that two maingroupings of techniques are available totreat and improve the reclamation sedimentand in-situ soils.

Groupings of available groundtreatmentsApart from conventional surcharging,techniques to improve the ground can begrouped into two main areas, namely: 1. Consolidation of the soft highly

compressible soils by installing verticaldrains or using vacuum consolidationwith surcharging or;

2. Improve, reinforce or stabilise the soils to reduce settlements and improve shearstrength and stiffness.

The suite of techniques falling under group 1comprises the installation of vertical drains,including sand drains or prefabricated verticaldrains (PVDs), in a square or triangularpattern, generally spaced at 1 m to 2 m.

Figure 1. Site layout.


Vacuum consolidation is a process wherebya vacuum pressure is applied to an areaalready installed with pvd’s to potentiallyincrease their effectiveness. Generally alltechniques here require the application of asurcharge loading to squeeze water out ofthe soft clay soils. Such loading must beequal to or in excess of the service loadingthe developed land will be subjected to. In vacuum consolidation, the vacuum pressureapplied contributes to the surcharge loading,and therefore actual surcharge heights arereduced. An additional important advantageof the vacuum is the isotropic nature of the vacuum pressure and the correlatedimprovement of the stability under preloading,reducing considerably the risk of slopefailure resulting from the surcharge.

Methods falling under group 2 includestone columns, piling the ground, massmixing the soils, or local mixing of the soilsover some form of grid by soil mixing.Where a grid of columns, piles, or in-situmixed columns is used, a bridging mattressmay be required across the site to transferthe surface loadings into the discrete soilsupports. Significantly less or no surchargingis required with these techniques, and theygenerally provide a significant time saving.However, these treatments are typicallymore costly. In certain parts of the world,freezing of the ground can even beconsidered as a viable solution.

Selection of Preferred TreatmentSolutionsConsideration was given to the most likelytreatment technique applicable for use in abroad scale application. The conclusion wasthat the techniques available under group 1would most likely be best suited for broadscale treatment. In addition they wouldpose no boundary differences with presentsites, where land consolidation techniquesusing surcharging alone have occurred.With relevance to the Port of Brisbanereclamation area, group 1 techniques i.e.PVDs, shaped as the preferred treatmentover vacuum for mass application, primarilybecause of the necessity of a 15 m deepcut-off wall to mitigate the local siteconditions (i.e. the occurrence of sandylayers) at the paddocks. Conversely, thevacuum consolidation process and solutions

available under group 2 are considered tohave merit in special situations such asedge treatments for berths or surchargestability. The mixing of techniques fromboth groups, however, poses difficulties attransition zones which would need to becarefully considered.

EXISTING GROUND CONDITIONS ANDDESIGN PARAMETERS

Target service loading and settlementcriteriaHistorically, ground treatment for the Port’sdeveloped existing reclamation area wasdesigned for an in-service settlementcriterion after construction of 150 mm in20 years. This criterion was associated withnominated design service loadings appliedto the adopted finished design pavementlevels as follows:• 36 kPa at marine terminal areas• 15 kPa at warehousing areas and road

corridors.

In planning for the future, however, PBC isconsidering increasing the design serviceloading of the marine terminals for futureberths up to 50-60 kPa. Further, new landzoning of integrated logistics has beencreated, sandwiched between the marineterminals and warehousing zones, with anapplicable design service loading of 36 kPa.This new zone covers areas previouslygazetted as warehousing and subjected toa design service load of only 15 kPa. Theincreased service loadings, if adopted posefurther challenges to the land developmentprocess in the new areas. Current thinkingis that PBC may need to adopt twoacceptance target service criteria in futureas follows:• Where the total thickness of

compressible clays and mud is less thana nominated thickness, say 10 m to 15 m, retain 150 mm residual settlementin 20 years of service;

• Where the total thickness exceeds thenominated thickness adopt an increasedtarget of 250 mm in 20 years of service.

Currently it is considered that a target of150 mm of residual settlement may not befeasible when using group 1 techniques,

PETER BOYLE

holds a Queensland University of

Technology (QUT) civil engineering degree

and is a Fellow of the Institution of

Engineers, Australia. He has over 25 years

of experience in the public and private

sectors covering all facets of port

development. He was the Alliance Design

Manager for the construction of the

Port of Brisbane’s FPE Seawall Project.

He currently has the lead technical role in

the reclamation and development of some

300 hectares of future Port Lands.

JAY AMERATUNGA

obtained his BSc degree from the

University of Sri Lanka, MEng from AIT,

Bangkok and PhD from Monash University

in Australia. He has over 30 years

experience and is currently a Senior

Principal at Coffey Geotechnics Pty Ltd,

Queensland. His expertise is in the areas

of soft soils, construction and numerical

analysis, and he works predominantly on

infrastructure and marginal lands projects.

CYNTHIA DE BOK

received her BSc and MSc in engineering

geology, from the Delft University of

Technology (TU Delft), the Netherlands.

She joined Coffey Geotechnics Pty Ltd,

Queensland in 2004 and initially worked

on the Wivenhoe Dam project before

taking on the challenge of the

geotechnical design and coordination

activities for the Port of Brisbane’s

Ground Improvement Trials.

BILL TRANBERG

holds a civil engineering degree and a

PhD in engineering from the University

of Queensland and is a Fellow of the

Institution of Engineers, Australia.

He has been involved with port

planning, design and construction

activities at the port for over 25 years.

A recent highlight was the 4.6 km long

FPE Seawall project, enclosing a

reclamation area of 235 hectares.

Bill currently has technical oversight

of all engineering development works

for the Port of Brisbane Corporation.


particularly where soft compressible claythicknesses including mud can total inexcess of 30 metres. In such cases thecreep settlement contribution from thedeeper layers, which may be only slightlyover-consolidated with respect to thedesign service loading, may be significantand may not be easily built out.

Geological Units In the existing reclamation and FPE areas,four distinct geological units have beenrecognised and they are listed from the top down in Table 1 and are described below.

The most compressible units at the site are:• Recent unit (dredged mud layer)• Holocene unit (clay layers)

In Figure 2 the basal surface of theHolocene unit underlying the study areas isshown in relative levels. The final designsurface elevations of the paddocks varyfrom 6m to 9m RL.

Recent sedimentsThese materials generally consist of moderndune and beach deposits and dredged fill.The soil types consist of silt, clay and fine to

coarse grained sand with interbeddedlayers of silt and clay. Shell layers may alsobe present. Material dredged from the riverchannels are deposited in the paddocksfrom a single point discharge, generatingvariable profiles in deposited materials.

Holocene sedimentsPrevious investigations have subdivided theHolocene sediments into an Upper andLower layer of low strength silty clay withshell bands (“marine clay”) separated by adiscontinuous layer of sand. The UpperHolocene layer generally consists of sandlayers interspersed with layers of soft claysand silts. Sand layers or lenses are relativelyfew or absent within the Lower Holocenelayer.

Pleistocene sedimentsThe Pleistocene layer is an older alluvialdeposit below the Holocene deposit andcomprises mainly over consolidated, verystiff to hard clays and medium dense todense sands and gravel immediatelyoverlying the bedrock. The compressibilityof these materials is relatively lowcompared to the soft/firm clays of theHolocene deposit.

Tertiary basaltThe weathered basalt bedrock of the PetrieFormation underlies the site and is describedas grey-green clay (extremely weatheredbasalt) grading downwards into dark greyto black, moderately to slightly weatheredbasalt.

Figure 2. Basal surface of Holocene layer (in m RL, with RL 0m equal to Low Water Port Datum).

Table I. Geological Units

Unit Description

Recent Dredged mud, marine and dune sands with layers of silt and clay.

This material may include fill, including dredged fill.

Holocene Normally consolidated marine clay, silt and sand.

Pleistocene Generally over-consolidated clay, sand and gravel.

Tertiary Weathered basalt bedrock of the Petrie Formation.


Preliminary Geotechnical ParametersBased on initial ground investigations of thestudy areas an average set of geotechnicalmaterial parameters for the dredged mudand the Holocene clay was chosen. It alsoenabled the creation of basic soil models atthe various study sites. These details wereincluded in the documentation package to be issued to the various prospectiveContractors to enable them to undertakesystem selection and preliminary designsand provide associated pricing applicable totheir systems and solutions. Creating suchdetails would enable CG and PBC to makefair comparisons between any proposalsreceived for ground improvement works.

These investigations also indicated low valuesfor the coefficient of consolidation (ch),compared to previous results for the dredgedmud layer and the Lower Holocene layer.The ch relates to the dissipation rate ofwater from the clay and therefore togetherwith the clay thickness and presence ofsand layers determines the consolidationtime. Settlement information from otherolder reclamation paddocks tends to indicatehigher rates of dissipation, likely to be dueto greater distribution of sand lenses withinthe dredged mud layer.

METHODOLOGY FOR SELECTION OFOPTIMAL GROUND IMPROVEMENTSYSTEM

After due consideration of all knownavailable ground treatment techniques, PBC decided to invite Expressions ofInterest (EOI) from specialist groundimprovement Contractors, either local orfrom overseas, interested in providingservices for the design, supply, installationand monitoring of suitable specialistground improvement systems to theexisting reclamation areas at the Port ofBrisbane.

Expressions of interestThe EOI document indicated that such systemsshould enable the reclaimed areas to bedeveloped by the Port in a considerablyshorter time frame than that achieved bysurcharging alone, providing acceptable in-service settlements and at the same time

resulting in cost effective and optimumtreatment solutions. Whilst the EOIdocument permitted any and all solutions,it did indicate that vertical drains includingPVDs and sand drains were likely solutions.Sand drains were included on account ofthe ready availability of sand at the Portsourced from the bay shipping channels.

To enable the actual performance and cost of any proposed ground treatmentsolution put forward by Contractors to be evaluated, the EOI document proposedthat one or two suitably qualified shortlisted Contractors would be selected andallowed to trial their systems on a four (4)hectare site. The documentation soughtthat Contractors provide preliminary costeddesigns and forecasts within their proposalsfor their systems of ground improvementbased on the initial geotechnical para-meters and basic soil models provided byCG and PBC and other relevant informationcontained in the EOI documentation.

Assessment of proposals receivedAt the closing of EOI submissions, eightproposals were received. Proposals werereceived from both local and overseasContractors. Overseas Contractors from The Netherlands, Germany, France and SE Asia were keen to offer their respectiveexpertise. The submissions receivedgenerally supported the use of PVDs as the preferred solution for the Port sites.

The EOI document contained six selectioncriteria that Contractors were advisedwould have their proposals assessedagainst. These criteria are listed in Table II.

PBC and CG assessed all Proposals receivedby scoring them against the selectioncriteria. This resulted in the short-listing of three preferred proposals. These threesubmissions could not be substantiallyseparated in terms of the selection criteria,with all three offering PVD solutions. Two of the three Contractors offeredvacuum consolidation systems as possiblesolutions in addition to PVDs.

Trials scheme adoptedPBC decided that there was considerablemerit in trialling all three Contractors rather

than further reducing the number of trialsand trialists from 3 to 2 or even to 1. Also, plans to develop future Berths 11 and 12 and associated backup lands furtheradvanced as the EOI process progressed.Accordingly PBC decided to expand thetrials scheme previously proposed to includethree trialists and trial PVDs over 3 sites of 3 ha each with a further special edgearea of 2.5 ha set aside for a vacuumconsolidation trial. The successful trialistsincluded three international companies: Van Oord, Boskalis Australia and AustressMenard (Menard). Contracts weresubsequently successfully negotiated witheach Trialist.

In addition, a scheme of assessment for theTrials during the design and constructionphase was established and agreed with allthree trialists. These criteria are largelybased on expanding upon the criteriacontained in Table II. It is further proposedto place a control or reference surchargeembankment, fully instrumented butwithout PVDs, for performance comparisonpurposes.

TRIALS PROGRAMME

A 3 ha site was provided to each Trialist forPVD installation. Each Trialist was given theopportunity to propose a trial schemewhich would generally enable maximumlearnings for each. The design proposalsput forward by the companies have shown alarge degree of thought and individualism.The trials utilise several different PVDs,varying both in core and filter type and arange of different spacings.

Boskalis is also trialling its BeauDrain-Svacuum consolidation system, which is anAustralian first. Menard is trialling theirproprietary vacuum consolidation systemalong a special edge site. The systemproposed includes a cut-off wall around theperimeter of the site to cut off the effectsof sand lenses in the upper Holocene layer. This is the first such application in Australia. A Menard vacuum system, without a cut-off wall, is currently installed in theBallina By-Pass Project, located in NewSouth Wales, Australia.


Table II. EOI assessment criteria

Criteria Issues

Overall Price One of the key factors in the assessment will be the all-up price for the groundimprovement treatment system, i.e. including all surcharging costs, monitoring, etc.

Past experience as designer & installer of A Proponent who has a demonstrated history as a proven ground improvement specialist ground improvement systems with sound results in projects similar to that to be undertaken at the Port of Brisbane will

be ranked highly against this criterion. This will also include expertise of personnelnominated to work on the project(s).

Ability to meet or exceed design criteria Proponents who can deliver the works to PBC’s preferred timelines whilst meeting the setand timings nominated criteria for the project will be ranked highly against this criterion. Ability to identify all risks

and provide acceptable contingency measures will also rank highly.

Proponent’s Financial capacity Proponents will need to demonstrate an adequate financial capacity to undertake theproject to be ranked highly against this criterion.

Warranties or Performance Guarantees Proponents who submit warranties or performance guarantees to deliver the areas withinthe residual settlement criteria nominated under the nominated loadings and design criteria will be highly ranked.

QA, Environmental, and Loss Control systems PBC is strongly committed to ensuring all its activities are carried out to the highest possible standards, including those relating to health, safety and the environment.Proponents who can demonstrate a similarly high commitment to these standards shall be ranked highly under this criterion.

Figure 3. The Boskalis/Cofra rig installing wick drains

in the Terminal 11 Trial area. Rig is an 80t machine

with 45 metre mast. The dredge pipe is in the

foreground. A Car Carrier vessel departing the

Brisbane River is visible in the background.

Figure 4. Close up of the Boskalis/Cofra rig during

installation of BeauDrain-S.


Figure 5. Van Oord is also a trialist in the

Terminal 11 Area. Stitching Rig is being filled

with new reel of wick drain. Note wick

anchor plates used to mark location of each

wick prior to installation.

Field trials progressAs at June 2007, Boskalis Australia hadcompleted installation of all wick drains andthe BeauDrain-S system (Figures 3 and 4).Van Oord had also completed all PVDinstallation works (Figure 5). After ratherextensive preparatory works, includingconstructing the 15 metre deep perimetervacuum cutoff wall, Austress Menardcompleted wick drain installation to all trialareas in May. The vacuum consolidationsystem installation including membrane,pipework and pumps was completed andthe system commissioned in June 2007(Figure 6).

The aerial photo (Figure 7) taken in June2007 shows the Austress Menard sitelocated in the S3A Trial area adjacent thePort’s Bird Roost with the Moreton BayMarine Park in the foreground, and the Portin the background. The black L is thevacuum trial area with (black) membrane,pipework and pumps installed. Behind thisis the white sand drainage layer placed overthe wick drain trial areas which extend upto the future road alignment. Surchargeplacement across both the wick drain andvacuum trial areas is currently underway.The 15 m deep cutoff wall was installedaround the perimeter of the L.

Given the expanded area of the trials andincreased loading parameters, some 1.5 millioncubic metres of surcharge is required to beplaced following the contractors’ installationworks. Installation of an extensive numberand type of monitoring instrumentsincluding piezometers, extensometers, deepsettlement plates, load cells and inclino-meters is now complete. Surface settlementmarkers on a 25 m grid are also in place.

The common view of the trialists is thatmeaningful interpretations of the measuredperformances of each trial area will be ableto be made 6 months after the surcharge is

Figure 6. The 80t excavator from Austress Menard

excavating the cutoff wall with the PVD

installation rig working in the background.


placed to full load. PBC plans to have theresults reviewed by CG experts, includingProf Harry Poulos, and externally by anappropriate expert. PBC is currently sourcinga suitable data capture and presentationsoftware system for use during the Trials.

Trialists have submitted samples of all PVDtypes being used in the Trials to enablerelevant laboratory testing of the PVDs tobe undertaken, including horizontal andvertical flow capacities in unkinked andkinked states. Kinking of PVDs is a possibleoutcome with certain PVD cores subjectedto large settlements.

Anticipated outcomes PBC and CG expect to achieve the followingoutcomes from the trials:1. Identify the effectiveness of PVDs for

local site conditions, including thicknessand depth of dredged mud and softclays plus natural drainage conditions

2. Identify the performance of PVDs fordifferent spacings in relation to localconditions

3. Identify differences in PVD performanceand cost implications

4. Verify consolidation times, and requiredsurcharge loadings using PVDs and usingvacuum consolidation

5. Identify performance of Contractors inrelation to design and construction.

As regards comparison of design andconstruction capabilities of three world-classcontractors, as the size of the trials hasexpanded, the 6 months results are notexpected to be available before the middleof 2008.

CONCLUSIONS

PBC identified that no single optimum solutionexisted to accelerate the consolidation ofsoils and dredged sediment to develop landwithin the future Port reclamation areas.Indeed several techniques are available andall have their advantages and disadvantagesin relation to time, cost and performance.By calling and receiving expressions ofinterest from specialist contractors both

locally and overseas and subsequentlyengaging three world-class contractors toundertake an extensive suite of trials, PBC believes it will arrive at an optimumsolution or series of working solutions.These solutions will be able to be utilized to develop large tracks of reclaimed landsuitable for Port industries and meet arange of future time demands.

Whilst undertaking trials over an area of11.5 ha looks excessive, it needs to berealized that this only equates to less than4% of the land areas to be developed (see Figure 1). It is considered that theadditional costs associated in undertakingthe trials, such as extra field and laboratorytesting and intense performance monitoring,will be recovered in the first couple of yearsof optimized broad scale treatment rollout.Further, it will provide for a significantdegree of confidence in land availabilitytimelines going forward that can be takenwith confidence to the market place.Implementing results of the Trials will allowquality land parcelling for development thatcan be released in a staged, timely manner.

PBC is aware and currently addressing thelogistical issues in instrumenting numerouslarge trial sites, data capture, processingand presentation and the placement of 1.5 million cubic metres of surcharge in an obstacle intense area.

The Trials have already generated significantinterest from industry, both Client andContractor.

REFERENCES

Ameratunga, J., Shaw, P. and Boyle, P. (2003).

Challenging Geotechnical Conditions at the

Seawall Project in Brisbane, Coasts and Ports

Conference (PIANC) 2003, Auckland, NZ.

Andrews, M., Boyle, P., Ameratunga, J. and

Jordan, K. (2005) Sophisticated and Interactive

Design Process Delivers Success for Brisbane’s

Seawall Project, Coasts and Ports Conference

2005, Adelaide, Australia.

Figure 7. An aerial photo taken in June 2007 shows the Austress Menard site located in the S3A Trial area adjacent

the Port’s Bird Roost with the Moreton Bay Marine Park in the foreground, and the Port in the background.

PANAMA CANAL ATLANTIC ENTRANCEEXPANSION PROJECT

JAN NECKEBROECK

ABSTRACT

The commercial importance of the PanamaCanal for over some 90 years cannot beoverstated. Vessels transiting through theCanal between the Atlantic to Pacific Oceanssave an enormous amount of time bringinggoods to market. However, given theincreasing size of cargo vessels, known aspost-Panamax, and the longer wait timesfor slots to transit the Canal, the need forwidening and deepening the Canal becameobvious. The Autoridad del Canal de Panama(Panama Canal Authority; ACP) is responsiblefor all dredging operations in the Canal and at the Atlantic and Pacific EntranceChannels. Usually dredging activities arecarried out by its own fleet of dredgers,including the hydraulic dredger Mindi anddipper dredger Rialto M. Christensen fordeepening and maintaining the waterway.

However, considering the scope of thework, the ACP decided to offer aninternational tender for deepening andwidening the Entrance Channels. Thisproved to be a good choice as one of themost serious challenges to any dredgingoperation in the Canal is that vesselstransiting the Canal must always havepriority. In fact during the execution of this

project, at least half of the channel widthhad to remain available for transiting vesselsat all times. With these requirements inmind, the ACP opted to employ internationalstate-of-the-art dredging equipment tofacilitate the dredging operations necessaryto keep the Canal functioning efficiently.The large capacity of these dredging shipsplus their self-propelling capability allowedthem to avoid obstructing transiting vesselsand to expedite the work.

INTRODUCTION

The Panama Canal, which first opened in1915, is an 80 km long waterway betweenthe Atlantic and Pacific Oceans. The Canalwas cut through the narrowest part of theisthmus in Central America that connectsNorth and South America eliminating thelong and treacherous voyage around SouthAmerica. The importance of the PanamaCanal for the world economy cannot beemphasised enough. Every year more than13.000 ships are transiting the Canal,

ranging from private yachts to luxury cruisersto Panamax cargo vessels. The commercialtransportation activities via the Canalrepresent approximately 5% of the world’strade and this figure continues to rise.Currently waiting times to find a slot (a confirmed time to transit the Canal) can take several days. Given the Canal’seconomic importance this situation isunacceptable and therefore plans have beenadopted to widen and deepen the Canal.

The Panama Canal consists in total of threesets of locks; the Gatún locks at the Atlanticcoast and the Pedro Miguel and MirafloresLocks at the Pacific coast (Figure 1). The entityof the Government of the Republic of Panamain charge of the operation, administration,management, maintenance and modernisationof the Canal is the Autoridad del Canal dePanamá (Panama Canal Authority; ACP).All operations within the boundaries of thePanama Canal are managed by the ACP.The entrance channel approaching theouter locks (Gatún Locks at the Atlanticside and Miraflores Locks at the Pacific side)also are part of the jurisdiction of ACP.

Given the scope of the work, on November 11, 2003, the ACP launchedinternational tenders for “Deepening of the

Above, Dredging operations in the Panama Canal must

always yield to the ongoing traffic of vessels transiting

the Canal. Under no circumstances may the transiting

vessels be obstructed.

Panama Canal Atlantic Entrance Expansion Project 27


Pacific Entrance” and the “Deepening and Widening of the Atlantic Entrance” ofthe Panama Canal. On the 22 July 2004 Jan De Nul NV received the Notice of Awardfor the Deepening and Widening of theAtlantic Entrance.

The contract works included the dredgingat the Atlantic Entrance Reach station –1K + 036 m up to the Gatún Locks NorthApproach Reach station 10K + 250 m. The navigation channel of the AtlanticEntrance, as from the outer breakwater tillthe locks, over a length of 11.286 km hadto be dredged till –14.2 m and the easternside of the Entrance Channel had to bewidened with 22.86 m up to 99.6 m. After the dredging, the total width of theEntrance Channel would become 198.12 mwith a slope 1V : 3H from –1K + 036 till 5K + 000 and a slope 1 V : 1 H from 5K + 010 to 10K + 250. In total a volumeof some 2.360.000 m3 had to be removedand placed at the designated disposal areas.

CHALLENGES

Several boundaries were contractuallyapplicable that presented significantchallenges to the dredging operation. For instance, the Contract stipulated thatthe dredging works were to be completedwithin a period of 24 months as from theNotice to Proceed. In addition, under nocircumstances could the transit of vesselsbe obstructed and strict limitations both inplace and time were imposed upon theContractor for the duration of the Contract.

Traffic in transitEveryday a convoy of southbound ships(primarily Panamax vessels) starts its voyageto transit the Panama Canal, leaving theanchor areas around 6 in the morning at theAtlantic side. As from 6.00 am until approxi-mately noontime vessels sail continuouslythrough the dredging area towards the GatúnLocks. At the same time the northboundships (also Panamax vessels) start transiting

the Miraflores Locks at the Pacific Side. Theseconvoys cross each other within the GatúnLake. Around 1 pm (13.00) the first north-bound vessels start to transit the GatúnLocks and sail towards the Atlantic Ocean.Normally around 8 pm (20.00) thenorthbound convoy has transited the Canal.

Traffic, however, does not stop at 8 pm.During the night is the time for the smallerships (small bulk carriers, tugboats, yachtsand such) to transit the Canal. In view ofthe daily schedule of the convoys in transit,ACP ruled out the presence of dredgingequipment in the areas 10K + 250 to 8K + 400 (the narrowest part of theAtlantic Entrance, close to the Gatún Locks)from 5.00 am to 8.00 pm. Additionally,during the execution of the dredgingworks, at least half of the channel widthhad to remain available for transitingvessels at all times.

CommunicationsIn order to optimise communications betweenthe dredging vessels and the transiting vessels,

ACP ordered the presence of an ACP pilotonboard the main dredging units (trailinghopper dredgers and a cutter suctiondredger) and a first mate of ACP onboardof all of the auxiliary equipment such asmulticast and tugboats.

Close coordination with all involveddepartments within ACP was crucial for thesmooth execution of the project. The Portcaptains at Cristobal Port, the Pilotdepartment, the Survey department andthe Safety and Environmental departmentswere involved at each stage of the projectand had to be informed about the progressand the interfaces of the dredging projecton regular basis.

Soil conditionsA particular challenge for the successfulexecution of any project in the PanamaCanal is the ever- changing soil conditions.In order to define the soil conditions of thisparticular section to be deepened andwidened, an extensive soil investigation wascarried out. This included geo-electrical

Figure 1. Location map of the Panama Canal

and the area to be dredged.

surveys, side-scan sonar surveys, a resistivitystudy and a bore-hole campaign. All ofthese were performed during the tenderperiod by the interested Contractors. In theend, the diversity of material to be dredgedat the Atlantic side ranged from silt, clayand fine sand to medium and hard rock(siltstone type Gatún).

The contracts for the dredging of theAtlantic and Pacific Approaches were thefirst major dredging contracts, other than a sporadic maintenance contract, for whichACP had issued an international tender. Up to then, ACP had performed maintenanceand capital dredging works within the Canalutilising its own equipment, mainly the 64 year old cutter suction dredger Mindi and the 30 year old mechanical dipperdredger Rialto M. Christensen (Figure 2).

EXECUTION OF THE DEEPENING ANDWIDENING OF THE ATLANTIC ENTRANCE

After submission of the insurance certificates,the Quality Control Plan, the MethodStatements, the Work Schedule and theDredging Execution Plan and their approval,ACP issued the Order to Proceed onOctober 2 2004.

The first phaseThe execution of the works startedimmediately with the trailing suction hopperdredger Francesco di Giorgio, a dredgerwith a 4400 m3 hopper capacity and a totalinstalled power of 6330 kW (Figure 3). The TSHD Francesco di Giorgio wasconstructed at the Astillero de Gijon – IZARin 2003 and is equipped with 2 electric-hydraulic Schottel rudder propellers of 2150 kW and a Schottel transverse bow-thruster system of 550 kW. These latterinstallations ensure a very high maneuverabilityof the dredging vessel, which was veryimportant during the operations in theCanal, particularly near the locks, becauseof the almost continuous traffic.

During the first phase of operations, the dredger removed the soft material at

the northern end of the Canal (between –1K + 036 and 4K + 000). This material,mainly silt and fine sand, was deposited atthe Northwest Breakwater Disposal Area(offshore from the Northern breakwater).Some soft material was also removedbetween stations 4K + 000 and 8K + 400.However, the steep slopes and hard materialrequired further use of a cutter suctiondredger in that area.

During this phase a total volume ofapproximately 1.000.000 m3 was dredgedafter which the Francesco di Giorgio wastemporarily demobilised from the site. As was expected, because of the highmanoeuverability of this dredger, noproblems with the transiting vessels wereencountered during the execution of thefirst phase.

JAN NECKEBROECK

graduated in 1998 as a MSc in

Constructional Engineering at the

Ghent University (Belgium) and joined

the Jan De Nul Group the same year.

For the last 9 years, he has been

employed in the Operational

Department on projects in the

Philippines, India, United Arab Emirates,

Singapore, Brazil, Argentina, Honduras,

Nicaragua and El Salvador. For the

Panama Project, he was the Project

Manager for execution of the dredging

works at the Atlantic Entrance.

Presently he is working as Deputy Area

Manager for the Americas at the head

office in Aalst, Belgium.

Figure 2. The Rialto M. Christensen has been at work in the Canal for 30 years.

Figure 3. TSHD Francesco di Giorgio working at

Atlantic Entrance with continuous freight traffic.

The second phaseWhile the dredging operations with thehopper dredger were going on, preparationfor the second phase of the works wasstarted. A cutter suction dredger (CSD) hadto be used to remove the medium to hardGatún rock in the Entrance Channel and todredge the steep slopes. The hard materialto be removed was mainly situated in thesouthern part of the Entrance Channel(8K + 400 to 10K + 250) and at the easternside. Additionally some hard spots between3K + 500 and 4K + 000 were encounteredin the middle of the canal.

In total three inland disposal areas for the materials of the CSD were prepared:Davis Landing Disposal Area, ShermanCenter Disposal Area and Telfers InlandDisposal Area. Davis Landing Disposal Areais situated at the eastern side of the Canalbetween 9K + 100 and 9K + 500.

The distance between the middle of the Canaland Davis is approx. 250 m. The disposalcapacity of this area was approx. 150.000 m3.Telfers Inland Disposal Area, also situated at the eastern side of the Canal between

5K + 000 and 5K + 800, is situated at adistance of approximately 500 m from theCanal axis. Sherman Center, with a disposalcapacity of approximately 650.000 m3, is situated at the western side of the Canalat a distance of 200 m from the Canal axis.

To accomplish the task, the self-propelledCSD JFJ De Nul was mobilised and cameover from Russia (Figure 4). This vessel, witha total installed diesel power of 27,240 kW,was built by IHC Holland in 2003. The factthat the cutter is self-propelled proved tobe an invaluable asset for the successfulexecution of the Project. Time lost becauseof continuous vessel traffic could besubstantially compensated for because ofthe efficient shifting of the CSD back to herposition.

The JFJ De Nul arrived at the Port of Cristobal,Panama in mid January 2005. The challengeof the rigorous restrictions of ACP regardingworking hours at the southern part of theEntrance Channel (from 8.00 pm till 5.00 ambetween 8K + 400 and 10K + 250) quicklybecame obvious. As stated earlier, the self-manoeuvering capability of the CSD

proved to be an asset. In addition, thegood communication and interactionbetween the ACP pilots (both onboard theJFJ De Nul and onboard the transitingvessels) and the crew, meant that theeffective operation time could be improvedconsiderably, even though the restrictionsof the minimum availability of half theCanal for traffic and the priority for thetransiting vessels was always observed(Figure 5).

Dredging at the eastern side commencedand the material was pumped via 500 mfloating pipes and shore pipes to the Davis Disposal Area and the Telfers InlandDisposal Area. Because of the limited sizeof the Davis Disposal Area and the locationof the Telfers Inland Disposal Area, part ofthe material from the eastern side had tobe pumped towards the Sherman CenterDisposal Area on the opposite bank as well.

For this purpose a sinker pipeline was placedon the bed of the Panama Canal in an areathat was previously dredged, which ensuredthat it would avoid being a hindrance to thetransiting vessels. The installation of the

Figure 4. Arrival CSD JFJ De Nul, transiting through Miraflores Locks.

sinker pipeline was carefully prepared andultimately done during a traffic window (2-3 hours at noontime) without disruptionof traffic (Figure 6).

After the widening of the eastern side theCSD JFJ De Nul was sent to deepen thewestern side of the Canal. Most of thematerial collected there was pumped intoSherman Center Disposal Area. In the centreof the canal some hard material was precutfor later removal by a trailing hopper dredger.

Owing to the presence of siltstone (Gatúnformation), the contract specificationsprescribed a slope of 1V : 1H at the easternside of the Canal between 8K + 400 and 10K+ 250. Nevertheless between 9K + 800 and10K + 250 soft plastic clay was encounteredand the 1V : 1H slope proved unstable. In thissection additional shore protection wasplaced in order to achieve a stable slope. In total a volume of 590 m3 of revetmentmaterial “Matacan 12-24 inch” was placedby dry equipment to protect the slope.

The cutter operations took in total aroundtwo months with a total volume ofapproximately 1.300.000 m3 being dredged.During the whole execution period everythingwas done to minimise interference with thetraffic. As a result none of the transitingvessels ran into delays because of theongoing dredging operations.

For the final clean up and for the removalof the material that had been precut, the

Francesco di Giorgio was remobilised to thejob by mid March 2005. At the same time asweeping operation was performed inorder to remove the last high spots.

At the end of the Original Contract, takingadvantage of the presence of this TSHDand convinced of the possibilities of thevessel to work in confined areas, ACPdecided to issue a Variation Order to carryout some maintenance dredging in front ofthe Gatún Locks (10K + 250 – 10K + 750).

After the official out-survey was carried out and further approval of all involveddepartments (Port Captain, ACP ContractingDivision, ACP Survey Department, ACP Pilotsand so on) had been obtained, the FinalAcceptance of the Contract on May 12, 2005was received. The execution period took only slightly over 7 months instead of the 24 months as foreseen in the tenderdocuments. The decision to work withmodern state-of-the-art vessels proved to becorrect choice for both Client and Contractor.

CONCLUSIONS

Working in such a dynamic environment asthe Panama Canal, where the first and onlypriority is to get the transiting vessels swiftlyand safely to the other end of the Canal,proved to be a major challenge for theContractor. The fact that under nocircumstances could the transit of vessels beobstructed meant that strict limitations bothin place and time were imposed upon theContractor for the duration of the Contract.

This challenge could only be converted intoa successful project by applying the highestquality standards and utilising modern state-of-the-art vessels. As a result none of thetransiting vessels ran into delays because ofthe ongoing dredging operations nor werethe dredging operations hindered by thetransiting vessels. In the end, because ofthis, the execution period for widening anddeepening the Canal took only slightly over7 months, far less than the 24 monthsallowed for in the tender documents.

Figure 5. CSD JFJ De Nul working at

Atlantic Entrance simultaneously

with transiting vessels.

Figure 6. Sinker operations by

means of a Multicat.

Panama Canal Atlantic Entrance Expansion Project 31

Useless Arithmetic. Why Environmental ScientistsCan’t Predict the Future.BY ORRIN H. PILKEY & LINDA PILKEY-JARVISPublished by Columbia University Press, New York,NY. 2007. 248 pages. Illustrated. Hardcover. Price: US$ 29.95

After teaching mathematics for 15 years, it was a bitawkward to receive a request to write a critical noteon a book with such a provocative title. Still it wasalso a challenge not to look at the book too muchthrough the eyes of an engineer.

When I saw the title of the book I had to think of oneof the statements in my PhD thesis written in 1987:Modelling is the attempt to describe reality withoutpretending to be reality. With this in mind the readercan approach the book in the right perspective.The authors are both scientists. Orrin H. Pilkey is theJames B. Duke Professor Emeritus of Geology andDirector of the Program for the Study of DevelopedShorelines at Duke University's Nicholas School of theEnvironment. Linda Pilkey-Jarvis is a geologist in theState of Washington's Department of Ecology, whereshe helps manage the State's oil spills programme.

They use a number of explicit examples to prove that the future cannot be predicted.The first one is cod fishing near Newfoundland. Based on models the quota for cod fishing weredetermined, but this did not lead to a stable situation.

The reality was much more complicated than themodels assumed. In addition, the models required agood description of the starting situation, which infact was not available. Even with the perfect modelthe rule applies: “garbage in, garbage out”.

The second example concerns the radioactivedistribution of high-level radioactive waste. How does this distribute over the years through thegroundwater flow? Also here the modelling has totake into account many unknowns. For example, to know the groundwater flow, one has to know the exact permeability to make a good prediction. It is almost impossible to know this for the wholearea concerned.

The third example is the rise of the sea level. There is no doubt that the sea level is subject to change.But whether or not this is caused by humaninterference is difficult to determine. There are toomany parameters involved of which many are almostimpossible to ascertain.

As a scientist and an engineer I do believe that it ispossible to create models for many physicalphenomena. In engineering we already have manymodels that have proven their usefulness. The factthat we can do strength and stiffness calculations andpredictions for many systems and constructions, likebridges, without these constructions to fail, provesthat there are many models that are reliable. We cansend people to the moon, based on mathematicalmodels.

One of the main reasons for rejecting the use ofmathematical models, the authors say, is the lack ofknowledge of initial conditions, confirming thestatement of “garbage in, garbage out”.After reading the book, my opinion about the use ofmathematical models has not changed. The bookmight put mathematical modelling in anotherperspective; the use of mathematical models topredict the future in any discipline depends on themodelling itself and on the input. If one of them isnot accurate or complete, the results will be doubtful.

This does not, however, mean we should stop creatingmore and more advanced models. One day we will beable to predict things that we cannot predict now. But we should stand with both our feet on the groundand realize which models are ready for use in the realworld and which models should be kept in thescientist’s environment for further development.

The book is available from Columbia University Pressat http://www.columbia.edu/cu/cup

DR.IR. S.A. MIEDEMA


BOOKS/PERIODICALS REVIEWED

Seminars/Conferences/Events 33

4th International Conference on PortDevelopment and Coastal Environment (PDCE) VARNA, BULGARIA SEPTEMBER 25-28, 2007

PDCE 2007 is being organised by the Black Sea Association

(BSCA) and supported by the Central Dredging Association

(CEDA). The day before the conference, the CEDA

Environmental Steering Committee will sponsor a one-day

training seminar on environmental aspects of dredging.

The seminar will be open to all conference participants.

The ESC will also present its 2007 year Best Paper Award

at this conference.

For further information contact:

PDCE 2007 Conference Secretariat

Black Sea Coastal Association

Capt. R. Serafimov 1, 9021 Varna, Bulgaria

Tel/Fax: +359 52 39 14 43

Email: [email protected]

CEDA website: http://www.dredging.org/event

BSCA website: www.bsc.bg

23rd Annual International Conference onContaminated Soils, Sediments and Water UNIVERSITY OF MASSACHUSETTS, AMHERST, MASSACHUSETTS, USAOCTOBER 15-18, 2007

The Annual Conference on Soils, Sediments and Water

has become the preeminent national conference in this

important environmental area. The conference attracts

700-800 attendees annually from Asia, Africa, Europe as

well as South and North America, in which a wide variety

of representation from state and federal agencies; military;

a number of industries including railroad, petroleum,

transportation, utilities; the environmental engineering

and consulting community; and academia are present.

“Expediting and Economizing Cleanups”, this conference’s

theme, will be supported by the development of a strong

and diverse technical programme in concert with a variety

of educational opportunities available to attendees.

For more information contact:

www.UMassSoils.com or

Denise Leonard, Conference Coordinator

Tel.: +1 413 545 12 39


or [email protected]

Conference on Contract Management for Land Reclamation LONDON, UKOCTOBER 23-24, 2007

Organised by CEDA, IADC and ICE, this event follows the

very successful Conference on Contract Management for

Dredging and Maritime Construction held in October 2006.

The Conference is divided into lectures presented by invited

specialists from all sides of the industry. Their presentations

will be followed by workshops in which aspects of the key

topics will be examined in more detail. With a focus on

large reclamation works, the subjects addressed will

include: Relation between end use and requirements;

boundary conditions (economical, ecological, social), subsoil

conditions and borrow area conditions; quality assurance in

project execution, contract management in practice and

pricing and valuation of contracts. In addition to the views

of experts, the aim is to have an open, constructive

dialogue amongst the main players, dredging contractors

and their clients and dredging and maritime consultants.

According to participants of the previous conference, such

dialogues are essential for planning and implementing

dredging works to the satisfaction of all parties. For all

those involved in reclamation works – clients, consulting

engineers, designers, dredging contractors, project

managers or construction lawyers – this event is a must.


info@iadc-dredging or [email protected]

www.dcm-conference.org or Richard Hart,

Tel.: +44 1460 259 776

E-mail: [email protected]

Port & Terminal Technology 2007 ANTWERP, BELGIUMOCTOBER 29-31, 2007

This Conference & Exhibition is aimed at those involved in

the effective development and operations of container port

and terminal facilities. It examines new trends and

technology to successfully develop and operate ports and

terminals. Topics in the conference programme are:

Port automation, Maintenance, Paving, Simulation, Cargo

handling, Security, Increasing capacity, Terminal design and

lighting, Fender systems, Increasing productivity for cargo

handling, Port & terminal efficiency, Impact of larger ships

on port infrastructures, and Environment.


www.millenniumconferences.com

SEMINARS/CONFERENCES/EVENTS


Europort MaritimeAHOY’ ROTTERDAM, THE NETHERLANDSNOVEMBER 6-9, 2007

Europort Maritime is one of the foremost international

trade fairs for maritime technology in ocean shipping,

inland shipping, shipbuilding, dredging, fishing and

related sectors. In addition to the exhibition which

attracts high-quality participants and visitors, the CEDA

Dredging Days are held simultaneously during the Europort

Maritime 2007 Exhibition.

For information on participation in the Exhibition contact:

Elly van der Loo at Ahoy’ Rotterdam:

Tel.: +31 10 293 32 50


Mr. J. Teunisse, Senior Account Manager

Tel.: +31 10 293 32 07


www.europortmaritime.nl

CEDA Dredging Days 2007AHOY’ ROTTERDAM, THE NETHERLANDSNOVEMBER 7-9, 2007

The theme of CEDA Dredging Days 2007 Conference is

“The Day After We Stop Dredging - Dredging for

Infrastructure and Public Welfare”. Before almost every

dredging project begins the question arises, “What will

the effects of dredging be?” Taking the offensive this time,

CEDA is reversing the question and asking, “What are

the consequences if we do not dredge?” CEDA intends

to raise a wider awareness of just how vital dredging is to

our infrastructure and to our economic and social welfare.

In five main sessions, international keynote speakers will tell

about typical issues in their area of work that have led or

had the potential to lead to the cessation of dredging or to

reducing dredging effort. They will answer questions such

as, Will our coasts be put at risk? What are the financial

and environmental costs of the alternatives? What will

happen to our domestic and social commerce? Will we get

the gravel we need for our buildings from land-based

quarries? Should we leave the contaminated sediment

where it is?

The Keynote Address will be given by Ronald E. Waterman,

MP, Province of South-Holland; Senior Adviser to the

Ministry of Transport, Public Works & Water Management.

Other Keynote speakers are Freddy Aerts, Head of Division,

Ministry of the Flemish Community, Maritime Access,

Belgium; Dr. Gary Patrick Mocke, Head, Coastal

Management Section (CMS), Dubai Municipality, Dubai,

UAE; Dr Ian Selby, Operations and Resources Director,

Hanson Aggregates Marine Ltd, UK; Dr. Ole Larsen, General

Manager, DHI Wasser &Umwelt GmbH, Germany; and

G. van Raalte, Royal Boskalis Westminster, the Netherlands.

An IADC Award for the best paper by a younger author

will be presented. To complement the conference, a small

dredging exhibition will be located in the area adjacent to

the technical session room. A Poster Competition will be

held for students and young professionals. The submission

deadline is October 15. The CEDA Dredging Days 2007 are

held in association with Europort Maritime 2007 Exhibition

for the international maritime industry.

For more information contact the CEDA Secretariat:

Tel.: +31 15 268 25 75


or the Dredging Days website: www.dredgingdays.org

37th Dredging Engineering Short CourseCENTER FOR DREDGING STUDIES, TEXAS A&M UNIVERSITY COLLEGE STATION,TEXAS USAJANUARY 7-11, 2008

The dredging engineering short course includes a mixture

of lectures, laboratories and discussions at the Texas A&M

University campus. The course is administered by the

Center for Dredging Studies, Ocean Engineering Program,

Zachry Department of Civil Engineering. Two textbooks

and course notes on all lecture material are provided.

A certificate and continuing education units are earned.


Dr. RE Randall, Director

Tel: +1 979 845 45 68

Fax: +1 979 862 81 62


www.oceaneng.civil.tamu.edu

PIANC COPEDEC VIIDUBAI UNITED ARAB EMIRATESFEBRUARY 24-28, 2008

After its successful start in 1983, it was decided to organise

the International Conference on Coastal and Port Engineering

in Developing Countries (COPEDEC) once every four years in

a different developing country. At the September 2003

meeting in Sri Lanka a merger agreement between COPEDEC

and PIANC (the International Navigation Association) was

signed and the tradition will be continued under the auspices

of the two organisations. For this reason, the newest

conference is being held with a five year interim instead of

four. The theme of COPEDEC VII will be “Best Practices in

the Coastal Environment”. Topics will include:

• Port, harbour and marina infrastructure engineering;

• Port, harbour and marina planning and management;

• Coastal stabilisation and waterfront development;

• Coastal sediment and hydrodynamics;

• Coastal zone management and environment;

• Coastal risk management;

• Short sea shipping and coastal navigation.

For further information on registration, participation

and conference organisation contact:

International Organising Committee, PIANC-COPEDEC

c/o Lanka Hydraulic Institute Ltd.

177, John Rodirigo Mawatha, Katubedda,

Moratuwa, Sri Lanka

Tel.: +94 11 265 13 06 / 265 04 71

Fax: +94 11 265 04 70


www.pianc-aipcn.org

Oceanology International 2008LONDON, UKMARCH 11-13, 2008

OI 2008 conference will be themed ‘Technology,

Sustainability and the Ocean Environment” and will explore

the vital role of marine science and ocean technology in

meeting the interlocking challenges posed by climate

change, satisfying future energy needs and ensuring

environmental and civil security. For 2008 the OI team has

partnered with the Institute of Marine Engineering, Science

and Technology (IMarEST) who will partner with the Society

for Underwater Technology (SUT) to develop the event’s

agenda-setting conference. The OI conference 2008

continues to be free of charge to visitors.

OI 2008 will be a combination of:

• a conference organised by the IMArEST and the SUT

• a large selection of suppliers for marine science and ocean

technology

• product demonstrations on the latest product

developments

• education and training on up-to-date issues

• a participating ships programme featuring vessels from

around the globe.


www.oceanologyinternational.com

Brazil Chapter Annual MeetingWestern Dredging AssociationINTERCONTINENTAL RIO HOTELRIO DE JANERIO, BRAZILDECEMBER 9-12, 2007

WEDA’s Brazil Chapter Conference presents "Dredging in

South America" at the Intercontinental Rio Hotel, Rio de

Janerio, Brazil. Spurred on by the success of the Panama

Chapter, WEDA is organising this First Brazilian Chapter

meeting. The congress and exhibition will focus on

dredging throughout South America, its impact on the

ever-expanding Global Economy and the areas Marine

Environment.

The theme of the conference will provide a unique forum

for all those working in the Western Hemisphere – Dredging

Contractors, Port & Harbor Authorities, Government Agencies,

Environmentalists, Consultants, Civil & Marine Engineers,

Surveyors, Ship Yards, Vendors, and Academicians – to

exchange information and knowledge with their professional

counterparts who work in the exciting and challenging fields

related to dredging. Important discussions on the history of

dredging in South America, as well as the impact that

dredging or the inability to dredge has on the world

economy and its environment will highlight the programme.

This announcement is a call for papers for this three-day

technical programme and exhibition. Topics of interest

include, but are not limited to:

• Current Dredging in Brazil

• Environmental Concerns

• History of Dredging in Brazil

• Rivers and Inland Dredging

• Beneficial Uses of Dredged Material

• Geotechnical Aspects

• Wetland Creation & Restoration

• Dredging for Beach Nourishment

• Dredging Systems & Techniques

• Automation in Dredging

• New Dredging Equipment

• Numerical Modeling

• Surveying and Equipment

• Contaminated Sediments

• Cost Estimating

• Dredging & Navigation

• Economic Benefits of Dredging

• Project Case Studies

The Technical Papers Committee will review all one-page

abstracts received and notify authors of acceptance. Final

Manuscripts are not required. Proceedings will be published

from power point presentations. Submission of abstracts

Seminars/Conferences/Events 35

CALL FOR PAPERS


imply a firm commitment from the authors to make a

presentation at the conference

All interested authors, including CEDA and EADA authors,

should mail their one page abstract to one of the following

members of the WEDA/Brazil Chapter Technical Papers

Committee. Submission deadlines are the following:

Submission of one-page abstracts: September 15, 2007

Notification of presenters: October 10, 2007

Dr. Ram K. Mohan, Chair

Blasland, Bouck & Lee

500 North Gulp Road, Ste 401

King of Prussia, PA 19496

Tel.: +610 337 76 01

Fax: +610 337 76 09


Mr. Paulo Roberto Rodriguez

Director General

Terpasa Dragagem

Campo de Sao Cristovao

348 Grupo 502 Sao Cristovao

Rio de Janeiro +20 92 14 40

Tel/Fax: +21 38 60 88 66


Dr. Robert E. Randall

Dept. of Civil Engineering

Texas A&M University

College Station, TX 77843-3136

Tel.: +979 845 45 68

Fax: +979 862 81 62 45 68


CEDA Dredging Days 2008CONFERENCE CENTRE ‘T ELZENVELDANTWERP, BELGIUMOCTOBER 1-3, 2008

With the title “Dredging facing Sustainability” CEDA

Belgium intends to rais a wider awareness of the

stakeholders to the efforts of the dredging world

– contractors, shipyards and consultants – to sustainable

development.

Topics include:

• How to tackle sea level rise – dredging for coastal flood

protection.

• Dredging as a key player in the energy discussion.

• Creating estuarine wetlands – vital ecosystems for

sustainable development.

• Dredging in sensitive areas

– balancing between socio-economic development and

nature conservation

– improving technology to achieve “no impact”.

• Efforts to reduce emissions in the Dredging Industry.

• Sustainability concerning decision process

For each of these themes the Papers Committee invites

submissions presenting recent challenging case studies

and precise descriptions of the ongoing developments.

Preference will be given to papers illustrating a multi-

disciplinary approach and highlighting special positive

contributions to sustainable development.

Abstracts (maximum 300 words) of papers to be considered

for the conference should be submitted by December 15,

2007 on-line to the Dredging Days. The Technical Papers

Committee will assess the abstracts.

Authors will be informed of the acceptance of their

abstract not later than February 15, 2008 and will be

invited to submit their full manuscript. They will also receive

the author’s instructions for the preparation of the full

manuscript, and the copyright transfer form.

Draft manuscripts, with a text of 4000 - 6000 words must

reach the conference secretariat before May 1, 2008.

All manuscripts will be refereed for quality, correctness,

originality and relevance. To assist in revision of the

manuscripts for the final submission, reviewer’s comments

will be sent to the authors by July 1, 2008.

The final camera-ready papers must be received by

September 1, 2008.


Technologisch Instituut

Att: Rita Peys

Desguinlei 214

BE 2018 Antwerpen, Belgium

Tel.: +32 3 260 08 61

Fax: +32 3 216 06 89


www.dredgingdays.org/20008


COVER

Traffic on the Panama Canal is constant, day and night, with more than 13,000 ships, from private yachts to

Panamax cargo vessels, transiting everyday. Even crucial dredging operations for deepening and widening the

Canal are not allowed to interrupt the flow of vessels (see page 27).

IADC

Constantijn Dolmans, Secretary General

Alexanderveld 84

2585 DB The Hague

Mailing adress:

P.O. Box 80521

2508 GM The Hague

The Netherlands

T +31 (70) 352 3334

F +31 (70) 351 2654

E [email protected]

I www.iadc-dredging.com

I www.terra-et-aqua.com

Please address enquiries to the editor. Articles in

Terra et Aqua do not necessarily reflect the opinion

of the IADC Board or of individual members.

Editor

Marsha R. Cohen

Editorial Advisory Committee

Roel Berends, Chairman

Constantijn Dolmans

Hubert Fiers

Bert Groothuizen

Philip Roland

Heleen Schellinck

Roberto Vidal Martin

Hugo De Vlieger

IADC Board of Directors

R. van Gelder, President

Y. Kakimoto, Vice President

C. van Meerbeeck, Treasurer

C. Marconi

P. de Ridder

P.G. Roland

G. Vandewalle

MEMBERSHIP LIST IADC 2007Through their regional branches or through representatives, members of IADC operate directly at all locations worldwide

AFRICADredging and Reclamation Jan De Nul Ltd., Lagos, NigeriaDredging International Services Nigeria Ltd., Ikoyi Lagos, NigeriaNigerian Westminster Dredging and Marine Ltd., Lagos, NigeriaVan Oord Nigeria Ltd., Ikeja-Lagos, NigeriaDredging International - Tunisia Branch, Tunis, TunisiaBoskalis South Africa, Pretoria, South Africa

ASIAFar East Dredging (Taiwan) Ltd., Taipei, Taiwan ROCFar East Dredging Ltd. Hong Kong, P.R. ChinaVan Oord ACZ Marine Contractors b.v. Hong Kong Branch, Hong Kong, P.R. ChinaVan Oord ACZ Marine Contractors b.v. Shanghai Branch, Shanghai, P.R. ChinaP.T. Boskalis International Indonesia, Jakarta, IndonesiaP.T. Penkonindo LLC, Jakarta, IndonesiaVan Oord India Pte. Ltd., Mumbai, IndiaBoskalis Dredging India Pvt Ltd., Mumbai, IndiaVan Oord ACZ India Pte. Ltd., Mumbai, IndiaJan De Nul Dredging India Pvt. Ltd., IndiaPenta-Ocean Construction Co. Ltd., Tokyo, JapanToa Corporation, Tokyo, JapanHyundai Engineering & Construction Co. Ltd., Seoul, KoreaVan Oord Dredging and Marine Contractors b.v. Korea Branch, Busan, Republic of KoreaBallast Ham Dredging (Malaysia) Sdn. Bhd., Johor Darul Takzim, MalaysiaTideway DI Sdn. Bhd., Kuala Lumpur, MalaysiaVan Oord (Malaysia) Sdn. Bhd., Selangor, MalaysiaVan Oord Dredging and Marine Contractors b.v. Philippines Branch, Manilla, PhilippinesBoskalis International Pte. Ltd., SingaporeDredging International Asia Pacific (Pte) Ltd., SingaporeJan De Nul Singapore Pte. Ltd., SingaporeVan Oord Dredging and Marine Contractors b.v. Singapore Branch, Singapore

AUSTRALIABoskalis Australia Pty. Ltd., Sydney, AustraliaDredeco Pty. Ltd., Brisbane, QLD, AustraliaVan Oord Australia Pty. Ltd., Brisbane, QLD, AustraliaWA Shell Sands Pty. Ltd., Perth, AustraliaNZ Dredging & General Works Ltd., Maunganui, New Zealand

EUROPEDEME Building Materials N.V. (DBM), Zwijndrecht, BelgiumDredging International N.V., Zwijndrecht, BelgiumInternational Seaport Private Ltd., Zwijndrecht, BelgiumJan De Nul n.v., Hofstede/Aalst, BelgiumN.V. Baggerwerken Decloedt & Zoon, Oostende, BelgiumBoskalis Westminster Dredging & Contracting Ltd., CyprusVan Oord Middle East Ltd., Nicosia, CyprusBrewaba Wasserbaugesellschaft Bremen m.b.H., Bremen, GermanyHeinrich Hirdes G.m.b.H., Hamburg, GermanyNordsee Nassbagger - und Tiefbau G.m.b.H., Wilhelmshaven, GermanyTerramare Eesti OU, Tallinn, EstoniaDRACE, Madrid, SpainDravo SA, Madrid, SpainSociedade Española de Dragados S.A., Madrid, SpainTerramare Oy, Helsinki, FinlandAtlantique Dragage S.A., Nanterre, FranceAtlantique Dragage Sarl, Paris, FranceSociété de Dragage International ‘SDI’ S.A., Lambersart, FranceSodranord SARL, Le Blanc - Mesnil Cédex, FranceDredging International (UK) Ltd., Weybridge, UK

Jan De Nul (UK) Ltd., Ascot, UKRock Fall Company Ltd., Aberdeen, UKVan Oord UK Ltd., Newbury, UKWestminster Dredging Co. Ltd., Fareham, UKIrish Dredging Company, Cork, IrelandVan Oord Ireland Ltd., Dublin, IrelandBoskalis Italia, Rome, ItalyDravo SA, Italia, Amelia (TR), ItalySocieta Italiana Dragaggi SpA ‘SIDRA’, Rome, ItalyEuropean Dredging Company s.a., Steinfort, LuxembourgTOA (LUX) S.A., Luxembourg, LuxembourgDredging and Maritime Management s.a., Steinfort, LuxembourgBaltic Marine Contractors SIA, Riga, LatviaAannemingsbedrijf L. Paans & Zonen, Gorinchem, NetherlandsBaggermaatschappij Boskalis B.V., Papendrecht, NetherlandsBallast Nedam Baggeren b.v., Rotterdam, NetherlandsBoskalis B.V., Rotterdam, NetherlandsBoskalis International B.V., Papendrecht, NetherlandsBoskalis Offshore b.v., Papendrecht, NetherlandsDredging and Contracting Rotterdam b.v., Bergen op Zoom, NetherlandsHam Dredging Contractors b.v., Rotterdam, NetherlandsMijnster zand- en grinthandel b.v., Gorinchem, NetherlandsTideway B.V., Breda, NetherlandsVan Oord ACZ Marine Contractors b.v., Rotterdam, NetherlandsVan Oord Nederland b.v., Gorinchem, NetherlandsVan Oord n.v., Rotterdam, NetherlandsVan Oord Offshore b.v., Gorinchem, NetherlandsVan Oord Overseas b.v., Gorinchem, NetherlandsWater Injection Dredging b.v., Rotterdam, NetherlandsDragapor Dragagens de Portugal S.A., Alcochete, PortugalDravo S.A., Lisbon, PortugalBaggerwerken Decloedt en Zoon N.V., St Petersburg, RussiaBallast Ham Dredging, St. Petersburg, RussiaBoskalis Sweden AB, Gothenburg, Sweden

MIDDLE EASTBoskalis Westminster M.E. Ltd., Abu Dhabi, U.A.E.Gulf Cobla (Limited Liability Company), Dubai, U.A.E.Jan De Nul Dredging Ltd. (Dubai Branch), Dubai, U.A.E.Van Oord Gulf FZE, Dubai, U.A.E.Boskalis Westminster Middle East Ltd., Manama, BahrainBoskalis Westminster (Oman) LLC, Muscat, OmanBoskalis Westminster Middle East, Doha, QatarBoskalis Westminster Al Rushaid Co. Ltd., Al Khobar, Saudi ArabiaHAM Saudi Arabia Company Ltd., Damman, Saudi Arabia

THE AMERICASVan Oord Curaçao n.v., Willemstad, CuraçaoCompañía Sud Americana de Dragados S.A., Buenos Aires, ArgentinaVan Oord ACZ Marine Contractors b.v. Argentina Branch, Buenos Aires, ArgentinaBallast Ham Dredging do Brazil Ltda., Rio de Janeiro, BrazilDragamex S.A. de C.V., Coatzacoalcos, MexicoDredging International Mexico S.A. de C.V., Veracruz, MexicoMexicana de Dragados S.A. de C.V., Mexico City, MexicoCoastal and Inland Marine Services Inc., Bethania, PanamaStuyvesant Dredging Company, Louisiana, U.S.A.Boskalis International Uruguay S.A., Montevideo, UruguayDravensa C.A., Caracas, VenezuelaDredging International N.V. - Sucursal Venezuela, Caracas, Venezuela

Terra et Aqua is published quarterly by the IADC, The International Association of

Dredging Companies. The journal is available on request to individuals or organisations

with a professional interest in dredging and maritime infrastructure projects including

the development of ports and waterways, coastal protection, land reclamation,

offshore works, environmental remediation and habitat restoration. The name Terra et

Aqua is a registered trademark.

© 2007 IADC, The Netherlands

All rights reserved. Electronic storage, reprinting or abstracting of the contents is

allowed for non-commercial purposes with permission of the publisher.

ISSN 0376-6411

Typesetting and printing by Opmeer Drukkerij bv, The Hague, The Netherlands.

TERRAETAQUAMaritime Solutions for a Changing World

Number 108 | September 2007International Association of Dredging Companies

terraet aqua...philip roland heleen schellinck roberto vidal martin hugo de vlieger iadc board of...

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