terraet aqua editorial - Dredging Engineering Research Laboratory

Number 108 | September 2007 

Maritime Solutions for a Changing World 

TERRAET 

AQUA

MEMBERSHIP LIST IADC 2007 

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

AFRICA 

Dredging and Reclamation Jan De Nul Ltd., Lagos, Nigeria 

Dredging International Services Nigeria Ltd., Ikoyi Lagos, Nigeria 

Nigerian Westminster Dredging and Marine Ltd., Lagos, Nigeria 

Van Oord Nigeria Ltd., Ikeja-Lagos, Nigeria 

Dredging International - Tunisia Branch, Tunis, Tunisia 

Boskalis South Africa, Pretoria, South Africa 

ASIA 

Far East Dredging (Taiwan) Ltd., Taipei, Taiwan ROC 

Far East Dredging Ltd. Hong Kong, P.R. China 

Van Oord ACZ Marine Contractors b.v. Hong Kong Branch, Hong Kong, P.R. China 

Van Oord ACZ Marine Contractors b.v. Shanghai Branch, Shanghai, P.R. China 

P.T. Boskalis International Indonesia, Jakarta, Indonesia 

P.T. Penkonindo LLC, Jakarta, Indonesia 

Van Oord India Pte. Ltd., Mumbai, India 

Boskalis Dredging India Pvt Ltd., Mumbai, India 

Van Oord ACZ India Pte. Ltd., Mumbai, India 

Jan De Nul Dredging India Pvt. Ltd., India 

Penta-Ocean Construction Co. Ltd., Tokyo, Japan 

Toa Corporation, Tokyo, Japan 

Hyundai Engineering & Construction Co. Ltd., Seoul, Korea 

Van Oord Dredging and Marine Contractors b.v. Korea Branch, Busan, Republic of Korea 

Ballast Ham Dredging (Malaysia) Sdn. Bhd., Johor Darul Takzim, Malaysia 

Tideway DI Sdn. Bhd., Kuala Lumpur, Malaysia 

Van Oord (Malaysia) Sdn. Bhd., Selangor, Malaysia 

Van Oord Dredging and Marine Contractors b.v. Philippines Branch, Manilla, Philippines 

Boskalis International Pte. Ltd., Singapore 

Dredging International Asia Pacific (Pte) Ltd., Singapore 

Jan De Nul Singapore Pte. Ltd., Singapore 

Van Oord Dredging and Marine Contractors b.v. Singapore Branch, Singapore 

AUSTRALIA 

Boskalis Australia Pty. Ltd., Sydney, Australia 

Dredeco Pty. Ltd., Brisbane, QLD, Australia 

Van Oord Australia Pty. Ltd., Brisbane, QLD, Australia 

WA Shell Sands Pty. Ltd., Perth, Australia 

NZ Dredging & General Works Ltd., Maunganui, New Zealand 

EUROPE 

DEME Building Materials N.V. (DBM), Zwijndrecht, Belgium 

Dredging International N.V., Zwijndrecht, Belgium 

International Seaport Private Ltd., Zwijndrecht, Belgium 

Jan De Nul n.v., Hofstede/Aalst, Belgium 

N.V. Baggerwerken Decloedt & Zoon, Oostende, Belgium 

Boskalis Westminster Dredging & Contracting Ltd., Cyprus 

Van Oord Middle East Ltd., Nicosia, Cyprus 

Brewaba Wasserbaugesellschaft Bremen m.b.H., Bremen, Germany 

Heinrich Hirdes G.m.b.H., Hamburg, Germany 

Nordsee Nassbagger - und Tiefbau G.m.b.H., Wilhelmshaven, Germany 

Terramare Eesti OU, Tallinn, Estonia 

DRACE, Madrid, Spain 

Dravo SA, Madrid, Spain 

Sociedade Española de Dragados S.A., Madrid, Spain 

Terramare Oy, Helsinki, Finland 

Atlantique Dragage S.A., Nanterre, France 

Atlantique Dragage Sarl, Paris, France 

Société de Dragage International ‘SDI’ S.A., Lambersart, France 

Sodranord SARL, Le Blanc - Mesnil Cédex, France 

Dredging International (UK) Ltd., Weybridge, UK 

Jan De Nul (UK) Ltd., Ascot, UK 

Rock Fall Company Ltd., Aberdeen, UK 

Van Oord UK Ltd., Newbury, UK 

Westminster Dredging Co. Ltd., Fareham, UK 

Irish Dredging Company, Cork, Ireland 

Van Oord Ireland Ltd., Dublin, Ireland 

Boskalis Italia, Rome, Italy 

Dravo SA, Italia, Amelia (TR), Italy 

Societa Italiana Dragaggi SpA ‘SIDRA’, Rome, Italy 

European Dredging Company s.a., Steinfort, Luxembourg 

TOA (LUX) S.A., Luxembourg, Luxembourg 

Dredging and Maritime Management s.a., Steinfort, Luxembourg 

Baltic Marine Contractors SIA, Riga, Latvia 

Aannemingsbedrijf L. Paans & Zonen, Gorinchem, Netherlands 

Baggermaatschappij Boskalis B.V., Papendrecht, Netherlands 

Ballast Nedam Baggeren b.v., Rotterdam, Netherlands 

Boskalis B.V., Rotterdam, Netherlands 

Boskalis International B.V., Papendrecht, Netherlands 

Boskalis Offshore b.v., Papendrecht, Netherlands 

Dredging and Contracting Rotterdam b.v., Bergen op Zoom, Netherlands 

Ham Dredging Contractors b.v., Rotterdam, Netherlands 

Mijnster zand- en grinthandel b.v., Gorinchem, Netherlands 

Tideway B.V., Breda, Netherlands 

Van Oord ACZ Marine Contractors b.v., Rotterdam, Netherlands 

Van Oord Nederland b.v., Gorinchem, Netherlands 

Van Oord n.v., Rotterdam, Netherlands 

Van Oord Offshore b.v., Gorinchem, Netherlands 

Van Oord Overseas b.v., Gorinchem, Netherlands 

Water Injection Dredging b.v., Rotterdam, Netherlands 

Dragapor Dragagens de Portugal S.A., Alcochete, Portugal 

Dravo S.A., Lisbon, Portugal 

Baggerwerken Decloedt en Zoon N.V., St Petersburg, Russia 

Ballast Ham Dredging, St. Petersburg, Russia 

Boskalis Sweden AB, Gothenburg, Sweden 

MIDDLE EAST 

Boskalis 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, Bahrain 

Boskalis Westminster (Oman) LLC, Muscat, Oman 

Boskalis Westminster Middle East, Doha, Qatar 

Boskalis Westminster Al Rushaid Co. Ltd., Al Khobar, Saudi Arabia 

HAM Saudi Arabia Company Ltd., Damman, Saudi Arabia 

THE AMERICAS 

Van Oord Curaçao n.v., Willemstad, Curaçao 

Compañía Sud Americana de Dragados S.A., Buenos Aires, Argentina 

Van Oord ACZ Marine Contractors b.v. Argentina Branch, Buenos Aires, Argentina 

Ballast Ham Dredging do Brazil Ltda., Rio de Janeiro, Brazil 

Dragamex S.A. de C.V., Coatzacoalcos, Mexico 

Dredging International Mexico S.A. de C.V., Veracruz, Mexico 

Mexicana de Dragados S.A. de C.V., Mexico City, Mexico 

Coastal and Inland Marine Services Inc., Bethania, Panama 

Stuyvesant Dredging Company, Louisiana, U.S.A. 

Boskalis International Uruguay S.A., Montevideo, Uruguay 

Dravensa C.A., Caracas, Venezuela 

Dredging 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 

CONTENTS 

EDITORIAL 2 

ENVIRONMENTAL MONITORING AND MANAGEMENT OF 3 

RECLAMATIONS WORKS CLOSE TO SENSITIVE HABITATS 

STÉPHANIE M. DOORN-GROEN 

Feedback 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 19 

AT THE PORT OF BRISBANE 

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

Historically the consolidation of reclaimed land takes about 10 years, but 

with the urgent need for land expansion, new ground improvement techniques 

are being tested to shorten the timeframe for preparing the land for use. 

PANAMA CANAL ATLANTIC ENTRANCE EXPANSION PROJECT 27 

JAN NECKEBROECK 

The challenge of widening and deepening the Canal without obstructing 

the heavy vessel traffic in transit was met by using state-of-the-art, large 

capacity, self-propelled dredging equipment. 

BOOKS/PERIODICALS REVIEWED 32 

Useless Arithmetic by Pilkey and Pilkey-Jarvis challenges conventional 

wisdom about the accuracy of predicative modeling. 

SEMINARS/CONFERENCES/EVENTS 33 

Autumn conferences in Bulgaria, Antwerp, London and 

Rotterdam are scheduled as well as a Call for Papers for CEDA 

Dredging Days 2008 in Belgium.

2 Terra et Aqua | Number 108 | September 2007 

EDITORIAL 

TERRAET 

AQUA 

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 products 

and 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 economy 

and the ecology. 

For the international dredging and maritime construction industry, innovation is an ever-present and 

continuous process. It is the driver that keeps the industry at the top of its game. Innovation means 

constantly striving to be better, to find more cost-effective dredging methods, more efficient ships 

and technologies, improved means of site investigations, and advanced environmental impact 

assessments. 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 are 

represented: Singapore; Brisbane, Australia; and the Panama Canal. Each of these projects is 

characterised by the significance of seeking, and finding, new ways to serve economic and 

environmental interests alike. 

In Singapore’s sensitive coral reef habitats, traditional methods for environmental management were 

not sufficient. This IADC Award-winning paper from WODCON XVIII explains the intricacies of an 

environmental monitoring and management system that helps dredgers comply with the strictest 

environmental 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 so 

that the land can be utilised more quickly. The aim is to cut the time needed for the new land to 

consolidate from 10 years to 5 years. 

And in this post-Panamax age, widening and deepening the Panama Canal – one of the essential 

arteries for world trade – has become a priority. Thanks to the unique capabilities of the modern 

international fleet of large, sophisticated dredging vessels, some of this work has already been 

successfully completed at an accelerated rate and without disturbance or interruption of vessels 

transiting the Canal. 

None of these projects would have been possible without the commitment of the dredging industry 

and its suppliers to research and development. The quest for innovation energizes the industry’s 

engineers, scientists and project managers to meet the daily challenges that come with maritime 

construction. It also inspires them to look to the future and to seek long-term solutions for potential 

challenges. 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 Gelder 

President, IADC Board of Directors

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

STÉPHANIE M. DOORN-GROEN 

ENVIRONMENTAL MONITORING AND 

MANAGEMENT OF RECLAMATIONS WORKS 

CLOSE TO SENSITIVE HABITATS 

ABSTRACT 

Traditional methods for environmental 

management of marine reclamation works 

close to sensitive habitats have generally 

not provided the level of control necessary 

to ensure preservation of these habitats. 

Obtaining the level of control necessary to 

assure authorities and non-governmental 

organisations (NGOs) of compliance with 

environmental quality objectives, requires 

quantifiable compliance targets covering 

multiple temporal and spatial scales. 

Of equal importance to allow feedback of 

monitoring results into compliance targets 

and work methods are effective and rapid 

response mechanisms. This article describes 

the successful implementation of 

comprehensive Environmental Monitoring 

and Management Plans (EMMP), based 

upon such feedback principles, which allow 

reclamation activities to proceed in close 

proximity to Singapore’s most important 

marine habitats under third party scrutiny. 

Specific focus is placed on describing the 

methods utilised to quantify compliance 

with daily spill budget targets and how 

such targets and compliances are assessed. 

To improve reliability, the spill budgets take 

into account specific habitat tolerance limits 

for varying magnitudes and durations of 

sediment loading. Refinements to sediment 

plume models were undertaken to enhance 

their ability to hindcast impacts from the 

contractors’ complex reclamation schedules. 

Methods for segregation of impacts and 

assessment of cumulative impacts were also 

integrated into the hindcast procedures. 

Finally, the article describes the updating 

of tolerance limits and confirmation of spill 

budgets via targeted habitat monitoring. 

To date, the EMMPs have been able to 

document compliance of the works to all 

pre-project environmental quality objectives 

at a level of reliability that cannot be refuted 

by third parties. This has minimised the 

developers’ and contractors’ exposure to 

public complaints and liabilities associated 

with environmental impacts. The EMMPs 

have thus allowed the reclamation activities 

to proceed in an efficient manner, whilst 

ensuring protection of the environment. 

The author wishes to acknowledge the 

important contributions of Thomas M. Foster, 

Above, For coral reef areas subject to direct impact, 

coral relocation is undertaken prior to the start of 

reclamations works. 

Regional Director Southeast Asia, DHI Water 

& Environment (S) Pte Ltd to this research. 

This paper was first presented at WODCON 

XVIII in June 2007 and was published in the 

conference Proceedings. It is reprinted here 

in a slightly revised version with permission. 

INTRODUCTION 

The tropical waters in Singapore provide 

excellent conditions for marine life, owing 

to relatively constant tropical water 

temperatures and frequent fresh ocean 

through flow from both the South China 

Sea and Melaka Straits. Coral, seagrass and 

mangrove habitats have been found to be 

relatively rich in Singapore. The diversity of 

the coral habitats in Singapore is confirmed 

by the fact that of the 106 coral genera 

existing world wide (Veron et al. 2000), 

55 genera are documented in Singapore 

waters alone (Tun et al. 2004), compared 

to 13 genera found in the Caribbean. 

For seagrass habitats, 12 species out of 57 

known species are found in Singapore 

(Waycott et al. 2004), whereas 24 out of 

54 true and minor mangrove species have 

been found in Singapore so far (Thomlinson 

1999). These numbers document the high 

diversity of marine habitats in a relatively


small environment as Singapore and 

emphasize the importance of marine 

habitat conservation in Singapore. 

Owing to the confined nature of Singapore 

waters and the presence of a large number 

of patch reefs, reclamation and associated 

dredging activities (in the following referred 

to generically as reclamation activities), 

often take place in very close proximity to 

coral reefs and seagrass areas. In addition, 

increasing industrial development results 

in developments also occurring close to 

sensitive industrial water intakes. 

Recognizing the value of these marine 

habitat and industrial resources, Singapore 

has established strict Environmental Quality 

Objectives (EQO) for marine construction 

activities. In order to document compliance 

with these EQOs, pro-active Environmental 

Monitoring and Management Plans (EMMP) 

based upon feedback monitoring principles 

are required for marine construction activities 

to proceed, when these are in close 

proximity to key environmental receptors. 

Introduced in Europe in the 1990s and 

refined during the EMMP works for the 

Øresund Link between Denmark and 

Sweden (Møller 2000) and Bali Turtle Island, 

Indonesia (Driscoll et al. 1997), feedback 

EMMP provides the level of responsiveness 

and documentation necessary to assure 

both authorities and other interest groups 

that the works meet the EQOs throughout 

the construction period. 

Based upon the strict nature of the EQOs, 

EMMPs in Singapore are required to 

establish compliance of the works across 

multiple 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 results 

of daily hindcast modelling compared 

to habitat tolerance limits throughout 

the potential impact area. 

The feedback mechanism allows for 

updating of the spill budget limits, response 

limits and tolerance limits, based on the 

results of sedimentation monitoring and 

habitat monitoring. To ensure the accuracy 

of the entire system, the performance is 

confirmed on a daily basis via control 

monitoring of sediment spill. 

This article presents how the various 

components of the EMMP are established and 

executed, together with the refinements 

necessary to ensure a level of responsiveness 

appropriate to the importance of the 

receptors. 

BASIC COMPONENTS OF THE EMMP 

The EMMP is the primary method of control 

to ensure EQOs relating to marine habitats 

and 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 is 

pro-active. It links the results of detailed 

numerical hindcast models of the sediment 

plumes resulting from reclamation activities 

with the results from online turbidity and 

current sensors, daily spill measurements 

and periodic habitat surveys, and compares 

these against the spill budget. 

The spill budget is the maximum allowable 

spill (daily, weekly and fortnightly limits 

are set), which will still ensure (based on 

the results of sediment plume forecast 

modelling) that the EQOs are met. 

As environmental receptors, like corals, 

have a different tolerance against 

suspended sediment levels than for example 

mangroves, individual tolerance limits are 

defined for each environmental receptor. 

The tolerance limits play an important role 

throughout the project, as the daily spill 

budget is based on these individual limits. 

Both tolerance limits and spill budgets are 

evaluated and updated during the project, 

based on results of the habitat monitoring 

campaigns. 

The main components of Feedback EMMPs, 

as implemented in Singapore are: 

i) Environmental Baseline 

Feedback variables are identified, 

instrumented and monitored for a 

statistically 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 the 

confirmation of the environmental 

quality objectives for the project 

and environmental tolerance limits. 

If compensatory works are required, 

such as coral relocation from direct 

impact areas, this is also undertaken 

at this stage of the EMMP. 

ii) 

Elaboration of work plans 

The appointed reclamation contractor 

elaborates a work plan, specifying the 

distribution of the work in time and 

space, procedures and equipment. 

iii) Assessment of work plans 

The effect of performing the work plan 

on the environment is assessed through 

the use of numerical sediment plume 

forecast modelling. 

vi) Revision of work plans 

If the forecasted impact resulting from 

implementation of the work plan leads 

to unacceptable effects, i.e. violation 

of EQOs, the work plan is revised and 

reassessed. Once the work plan is 

finalised a final EMMP specification 

document is drawn up that specifies 

the detailed execution, response and 

management process for the EMMP. 

In particular, the final EMMP specification 

includes a spill budget (for each phase 

of the reclamation), which is the limiting 

amount of spill that will still result in the 

EQOs being met and against which the 

day-to-day control of the reclamation 

work can be assessed. 

v) Construction phase 

Reclamation commences.


Stéphanie M. Doorn-Groen receiving an IADC 

Award for young authors from Constantijn 

Dolmans, Secretary General of IADC. 

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 

International Association of Dredging Companies 

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. 

vi) Compliance monitoring 

Monitoring of daily compliance variables 

against the pre-determined sediment 

spill limits (spill budget). If daily 

compliance limits are violated, mitigation 

actions are established and implemented. 

If no violations of limits occur, reclamation 

work and daily monitoring continue. 

Compliance monitoring is reported on 

a daily basis and to ensure the level of 

responsiveness, reporting is required a 

maximum of 45 hours in arrears of any 

reclamation activity. 

vii) Control monitoring 

Monitoring of real time measurements 

and comparison to response limits, 

such as online turbidity data or weekly 

sedimentation data. If no violations of 

limits occur, work and control monitoring 

continue. Control monitoring is reported 

to the time scale of the monitoring 

activity (daily or weekly). 

viii) Spill hindcast 

Spill hindcast documents the impact 

of the reclamation progress on the 

environment remote to the work site. 

The spill hindcast is based upon realized 

production schedules, composition of 

fill material and actual tide conditions. 

The assessment is made through the 

use of numerical sediment plume 

hindcast modelling, with the hindcast 

updated every day. Reporting of the 

hindcast is made a maximum of three 

days in arrears of the actual progress of 

the reclamation works so that remote 

impacts are captured prior to them 

becoming significant. 

ix) Habitat monitoring 

Monitoring of biological habitat 

feedback variables is performed to an 

appropriate time schedule for the 

anticipated response rates. This is typically 

once every three months for coral reefs, 

seagrass beds and mangrove areas. 

x) Evaluation of construction phase 

Based on the results of the biological 

monitoring of feedback variables and 

the results of the numerical spill 

hindcast modelling of the realized 

construction process, the temporal and 

spatial impacts of the construction 

phase are assessed. If EQOs are violated, 

mitigation actions are established, 

assessed and undertaken. On the basis 

of the realized impacts, environmental 

criteria (tolerance limits) and compliance 

criteria (spill budgets) for the next 

construction phase are updated (the 

feedback loop). 

xi) Next construction phase 

The construction and monitoring process 

returns to task v) for each major stage 

of the reclamation and the process is 

repeated until reclamation is complete. 

xii) Completion of construction 

An environmental audit is produced at 

the end of the construction period as 

formal documentation of the impacts 

realised during the construction phase. 

This is based upon the result of the 

compliance, control, habitat and support 

monitoring together with the results of 

the hindcast modelling of impacts. The 

environmental audit is based on a final 

habitat survey usually carried out three 

months after the end of construction. 

The main advantages of this approach to 

EMMPs are: 

• Compliance measurements are targeted 

in the sediment plume resulting from 

dredging and reclamation activities, 

as close as possible to the source of 

spill at the given time of measurement. 

This provides a much more accurate 

measurement of suspended sediment 

spill than can be achieved via fixed 

turbidity sensor stations, which often 

lie outside the sediment plume for 

individual dredging or reclamation 

operations. 

• Numerical sediment plume forecast 

models allow assessment of changes 

to the spill budget for variations in 

complex reclamation schedules and 

varying tide and ocean current 

conditions, thereby ensuring the spill 

budget is the most appropriate for the 

given stage of the works given the 

specific equipment to be utilized and 

timing of the activity. 

• The hindcast model documents the 

spatial distribution of impacts at all


the receptor sites in the vicinity of the 

reclamation site with far broader spatial 

scale and finer temporal resolution than 

can be achieved via habitat monitoring 

in isolation. 

• The hindcast model keeps a running 

balance of the cumulative sedimentation 

impact levels based on actual production 

provided by the reclamation contractor. 

Increasing levels of sedimentation can be 

detected at an early stage and mitigating 

measures can be applied, if necessary. 

• The combined use of daily spill 

compliance monitoring, control 

monitoring and hindcast modelling allows 

the EMMP to respond rapidly and reliably 

to different temporal impact scales (from 

for example, short term exceedences 

resulting from, for example, unexpected 

events, to long-term trends resulting 

from, for example, deterioration in the 

quality of fill material). 

• The feedback loop ensures that tolerance 

limits and resultant spill budgets are 

consistent with the specific sensitivity 

of the environmental receptors in the 

impact area. 

ENVIRONMENTAL QUALITY OBJECTIVES 

In order to set EQOs for a project, it is 

essential that a classification scale is adopted 

to define the scale of impacts that may be 

allowed at a given environmental receptor. 

The following scale of impact classifications 

has been adopted for several projects in 

Singapore: 

• No impact: Changes are significantly 

below physical detection level and 

below the reliability of numerical 

models, so that no change to the 

quality or functionality of the receptor 

will occur. 

• Slight impact: Changes can be resolved 

by numerical sediment plume models, 

but are difficult to detect in the field as 

they are associated with changes that 

cause stress, not mortality, to marine 

ecosystems. Slight impacts may be 

recoverable once the stress factor has 

been removed. 

• Minor impact: Changes can be resolved 

by the numerical models and are likely 

to be detected in the field as localized 

mortalities, but to a spatial scale that 

is unlikely to have any secondary 

consequences. 

• Moderate impact: Changes can be 

resolved by the numerical models and are 

detectable in the field. Moderate impacts 

are expected to be locally significant. 

• Major impact: Changes are detectable 

in the field and are likely to be related 

to complete habitat loss. Major impacts 

are likely to have secondary influences 

on other ecosystems. 

The task of defining EQOs rests with the 

authorities and is made on an area by area, 

habitat by habitat basis. For reclamation 

projects in Singapore, “Slight Impact” is 

typically allowed in the area immediately 

adjacent to (within 500 m) of the work 

area, whilst “No Impact” is required for all 

environmental receptors remote from the 

work area. For coral reef areas subject to 

direct impact (i.e. under the reclamation 

profile), it is presently common practice in 

Singapore to compensate for the habitat 

loss by undertaking a coral relocation 

exercise prior to start of reclamation works. 

TOLERANCE LIMITS AND 

ENVIRONMENTAL QUALITY OBJECTIVES 

The linkage between project EQOs and 

spill budget depends on the method of 

reclamation and on the tolerance limits of 

the various environmental receptors, which 

in turn depends upon the pre-project 

external stress levels on the ecosystem. 

In Singapore, initial tolerance limits for 

the most sensitive marine habitats (corals 

and seagrass) have been established based 

upon extensive literature review and DHI’s 

experience from similar projects in the 

South East Asia region. 

These tolerance limits have then been 

refined over the course of several projects 

in Singapore, based upon the results of 

project specific habitat monitoring. 

Presently, these limits, as presented below, 

are believed to be the most relevant set of 

tolerance data available for coral reefs and 

seagrass beds subject to incremental 

reclamation impacts on top of elevated 

external (non-project related) stress levels. 

Coral tolerance to suspended 

sediments 

In simplified terms, as hard corals are 

dependent on symbiotic photosynthesizing 

zooxanthellae for their nutrient supply and 

survival, they are sensitive to increased 

turbidity levels as the reduction in light 

penetration through the water column 

adversely affects the photosynthesis 

process. Perhaps more seriously, elevated 

sedimentation levels can clog the corals’ 

respiratory and feeding system, whilst also 

causing complete light extinction to the 

impacted area of the colony. 

The level of sensitivity depends on the 

characteristics of the corals, with plate 

corals like Pachyseris sp. proving the most 

sensitive to increased sedimentation and 

least sensitive to reduction in light 

penetration. Conversely, branching corals 

such as Acropora sp. show the opposite 

sensitivity trend. Clearly, other impacts such 

as degradation of substrate impacting 

attachment of coralline larvae are also 

important to the overall impact level 

experienced by a reef. However, the present 

state of the art cannot quantify such 

details, which are therefore captured via 

the habitat monitoring component of the 

EMMP rather than via the tolerance limits. 

Background levels vary from region to 

region and are very site specific. Research 

from the Barrier Reef (Harriot et al. 1988) 

indicates that these corals are tolerant to 

levels of suspended sediments up to 4 mg/l 

(absolute concentration). However, studies 

in Hong Kong have shown tolerance levels 

up to 10 mg/l. Extensive monitoring data 

from multiple projects in Singapore (where 

changes in reef health, measured as a 

function of live hard coral cover and 

diversity, has been compared to measured 

and predicted suspended sediment and 

sedimentation levels), has allowed the 

development of an coral tolerance matrix 

for excess (above background) suspended 

sediment concentrations, see Table I. 

This table is found to be applicable for the 

elevated background turbidity levels common 

in Singapore and the typical Singapore reef 

morphology, which is dominated by the 

more resilient massive corals and plate 

corals, as shown in Figure 1.

Figure 1. Typical coral habitats in Singapore. 

Coral tolerance to sedimentation 

Coral sensitivities to sedimentation are 

determined largely by the particle-trapping 

properties of the colony and the ability of 

individual polyps to reject settled materials 

(Figure 2). Horizontal plate-like colonies and 

massive growth forms present large stable 

surfaces for the interception and retention 

of settling solids. Conversely, vertical plates 

and upright branching forms are less likely 

to retain sediments. 

A threshold (absolute) value of 0.1 kg/m 2 /day 

has previously been adopted as the critical 

value for corals in Environmental Impact 

Assessments in Hong Kong. However, 

monitoring data from Singapore indicates 

that an incremental value of 0.05 kg/m 2 /day 

is more appropriate for the type of coral 

habitats and existing stress levels in Singapore 

waters. Based on these Singapore data sets, 

the tolerance limits presented in Table II are 

found to be relevant for sedimentation 

impact on corals for reefs with naturally high 

background sedimentation levels, assuming 

a net deposition density of 400 kg/m 3 . 

Seagrass tolerance to suspended 

sediments 

Productivity of seagrass can be limited owing 

to reduced light penetration resulting from 

the presence of algal blooms and suspended 

sediments. Seagrass requirements for light 

penetration have been well described by 

multiple authors, with the habitat being 

confined to water depths where light levels 

are above 10% to 15% of surface 

irradiance. For the normal tidal range 

experienced in the Singapore area, these 

Table I. Impact severity matrix for suspended sediments on corals in 

environments with high background concentrations 

Severity 

No Impact 

Slight Impact 

Minor Impact 

Moderate Impact 

Major Impact 

figures concur well with observations within 

Singapore waters, which indicates that 

seagrass are generally limited to seabed 

areas shallower than –1 m CD. At low tide, 

many seagrass beds in the Singapore area 

Definition (excess concentration) 

Excess Suspended Sediment Concentration > 5 mg/l 

for less than 5% of the time 






for more than 20% of the time 











Table II. Impact severity matrix for sedimentation impact on corals 

Severity 

Definition (excess sedimentation) 

No Impact 

Sedimentation < 0.05 kg/m 2 /day (

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

suspended sediment load in the Singapore 

area, it is reasonable to assume that the 

outer limits of the seagrass are well 

adapted (in terms of water depth) to shortterm 

fluctuations in the background 

concentration of 5 to 10 mg/l, such that 

excess loadings higher than 5 mg/l will be 

required to stimulate a noticeable habitat 

change. These findings, coupled with 

monitoring experience from the SE Asia 

region, result in the proposed impact 

severity matrix presented in Table III. 

Seagrass tolerance to sedimentation 

The growth rates of seagrass are high. 

Growth in the order of 1 to 2 cm per day 

has been recorded for example for 

Thalassia sp. (Durate et al. 1999) whilst 

growth rates in the order of 0.6 cm per day 

have been recorded for Enhalus sp. in Malaysia. 

Therefore, the short-term survival of 

seagrass beds, which depends on anaerobic 

performance, will only be impacted in the 

case of very high sedimentation rates. Such 

critical sedimentation rates will normally 

only occur very close to a reclamation site. 

Based on experience in the SE Asia region, 

the following impact severity matrix is 

presented for sedimentation impact on 

seagrass (see Table IV). Other impacts 

resulting from increased sedimentation, 

such as change in composition of substrate, 

are clearly also important to the overall 

impact levels experienced by a seagrass bed, 

but such detailed impacts are difficult to 

quantify and are therefore captured via the 

habitat monitoring component of the EMMP. 

Table III. Impact severity matrix for suspended sediment impact on Seagrass 

in high background environments 

Severity 

No Impact 

Slight Impact 

Minor Impact 

Moderate Impact 

Major Impact 

Definition (excess concentrations) 













Excess Suspended Sediment Concentration > 75mg/l 


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

background environments 

Severity 

Definition (Excess sedimentation) 

No Impact Sedimentation < 0.1 kg/m 2 /day (


Mangrove tolerance to suspended 

sediments and sedimentation 

Mangroves can be considered to be very 

tolerant to the range of suspended 

sediment loads that may be generated 

from dredging and reclamation activities. 

Of the various mangrove species, those 

with pneumatophore root systems are the 

most sensitive to sedimentation (Thampanya 

et al. 2002), but even mangroves with 

pneumatophore root systems are only 

likely to be stressed when prolonged 

sedimentation reach levels from 10 cm up 

to 30 cm. This level of sedimentation is 

unlikely to occur outside the work area, 

and mangroves are thus not considered as 

sensitive receptors. Never-the-less, as EQOs 

are normally specified for mangrove areas, 

they are normally included in the habitat 

monitoring campaigns for reclamation 

EMMP in Singapore. Figure 4 presents a 

typical mangrove habitat in Singapore area. 

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

Rhizophora stilt root system (background). 

Visual impact and detection limits 

In the turbid environments that are found 

around Singapore, low concentration 

sediment plumes in the surface of the 

water column are generally not visible 

(based upon results of remote sensing 

analysis) if the excess concentration above 

background does not exceed 5 mg/l. 

A realistic measurable visual detection limit 

for non-recreational areas (in the Singapore 

high background turbidity context) would 

be 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 suspended 

sediments 

For many industrial intakes the absolute 

tolerance limit to suspended sediments is 

not known by the operators. In such cases, 

the most practical method for establishing 

a tolerance limit is to carry out statistical 

analysis on long-term background suspended 

sediment data from the immediate area of 

the intake. It is then possible to carry out a 

test for no statistical change (at a confidence 

limit agreed with the operator) for the 

various time scales of interest (daily, weekly, 

monthly and 6 monthly tests are normally 

considered in Singapore). 

DAILY COMPLIANCE MONITORING 

Based on the EQOs, spill budgets are 

defined for each stage of the reclamation 

works. The spill budgets are updated as 

work progresses and feedback information 

confirms their applicability or indicates a 

relaxation or tightening is warranted. 

The contractor’s compliance to the daily spill 

budget is assessed on a daily basis against daily 

spill budget targets and on a weekly basis 

against weekly and fortnightly spill budget 

targets. Typically, the fortnightly spill budget is 

60% of the daily spill budget, reflecting the 

ability of most receptors to cope with higher 

levels of stress if they are short-term or intermittent 

in nature. Daily compliance to spill 

budget targets must be established within a 

time frame which will allow response before 

any non-compliance will pose a threat to the 

environment. Therefore, daily compliance 

monitoring requires strict daily procedures for 

data delivery from the contractor, to ensure 

daily spill calculations, laboratory analysis daily 

compliance analysis and reporting can be 

carried out in a timely manner. 

On daily basis the contractor supplies: 

• Realised dredging volumes per dredger 

for every single trip, including location 

and method; 

• Start and end time of dredging cycle, 

including delays; 

• Realised reclamation volumes per 

dredger for every single trip, including 

location and method; 

• Start and end time of reclamation cycle, 

including delays; 

• Representative sediment samples from 

each load to be analyzed for fine 

contents by an external laboratory. 

In addition to the data provided by the 

contractor, suspended sediment samples 

are taken in the main plume discharge of 

the reclamation site (either as suspended 

sediment samples (TSS) or sediment flux 

measurements using acoustic backscatter 

technology). The location and the time of 

the sampling reflect the reclamation 

activities of the contractor and the samples 

are analysed for TSS by an external laboratory. 

This analysis provides a second method of 

control and serves as a validation for the 

spill calculation and performance of the 

numerical hindcast models. Based upon the 

fines content of the fill and dredge material 

and method of reclamation an empirical 

estimate of the total spill is made, for each 

reclamation/dredging operation over the 

preceding 24 hr period. The resultant total 

can then be compared to the spill budget


Figure 5. Daily operating procedure for 

daily compliance monitoring. 

on the level of compliance established for 

the 24 hr period. A typical example is shown 

below for rainbowing operations. 

Spill of fines leaving immediate dredging 

area = Load volume * fines % * 25% 

Although it is recognised that the specific 

spill is dependent on many factors such as 

the prevailing water depth and current 

speed, this simple empirical formula has 

proved to be a reliable method for 

estimation of spill for sand placement in 

the typical range of physical conditions 

encountered in Singapore. 

Validation of the spill calculation is 

subsequently provided by the TSS or 

sediment flux measurements in the plume. 

However, for the purpose of the daily 

compliance monitoring a simple, yet 

reliable, empirical formulation is required 

to meet the reporting time scale. 

Figure 5 presents a general flowchart of 

the complex daily operating procedures 

required to establish compliance with spill 

budget targets to a time frame which will 

allow response before any non-compliance 

will pose a threat to the environment, 

which has been defined as a maximum of 

45 hrs in arrears of any activity on site. 

Figure 6 presents an example of the daily 

spill calculations over a period of five 

months based on the empirical methods 

described above and validated by the 

control sampling in the sediment plume. 

This figure indicates that the daily spill 

budget was exceeded for a period in 

April. Mitigating measures were introduced 

and subsequently the spill budget was 

achieved for the remainder of the 

reclamation work. 

Figure 6. Spill results from 

reclamation operations.


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. 

DAILY HINDCAST MODELLING 

Based upon the information provided by 

the contractor in terms of time and location 

of activities and the calculated spill, daily 

spill hindcast simulations are run in order to 

establish the temporal and spatial impacts 

of the sediment plumes released from the 

work area. 

Hydrodynamic model setup and 

performance 

The daily hindcast modelling is based upon 

DHI’s extensively verified 675/225/75/25 m 

MIKE 21 nested grid hydrodynamic model 

of the Singapore Straits, which was 

developed in 2001 and is being continuously 

refined on the basis of daily real time current 

measurements. 

Figure 7 shows the overall regional model 

grid coverage utilised for EMMP projects in 

the Singapore area, whilst Figure 8 presents 

an example of the model performance 

which meets relevant international standards 

such as UK Foundation for Water Research 

Publication Ref FR0374 “A framework for 

marine and estuarine model specification in 

the UK”. The 25 m Model resolution is 

adopted in the specific area of reclamation 

to ensure all relevant local hydrodynamic 

factors, which may affect the plume 

transport and dispersion are resolved. 

Bathymetric survey data are taken directly 

from digital navigation charts, 

supplemented by project specific survey 

data, which is updated on a weekly basis 

for reclamation progress in the specific 

project areas. 

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 and 

performance 

Calibration and validation of DHI’s sediment 

plume hindcast model for Singapore waters 

has been carried out over the course of 

several projects. A typical example of the 

model performance is provided in Figure 9. 

Throughout the course of the EMMP, the 

performance of the model is verified on a 

daily basis, either by direct TSS measurements 

within the sediment plume or via sediment 

flux transects through the plume. 

Critical shear stress for erosion and 

deposition 

A vital factor to the performance of the model 

in terms of documenting impacts on coral reef 

habitats is the parameterisation of the critical 

shear stress for erosion and deposition over 

the reef areas. The complex morphology of 

coral reefs on both micro and macro scales, 

leads to an increased tendency for deposition 

to occur and a reduced tendency for 

re-suspension. Extensive testing and 

comparison to sediment trap data collected 

on a weekly basis has been undertaken, 

leading to the following conclusions 

concerning average critical shear stress 

parameters for deposition and re-suspension 

of fines over coral reef areas in Singapore: 

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 

Location survey vessel 

Water samples were taken 

TSS results: 

Point 15: 2.5 mg/l 





• Critical shear stress for deposition of 

fine material over coral reef: 0.6 N/m 2 

• Critical shear stress for re-suspension of 

initial deposits over coral reef: 1.5 N/m 2 

Measured incremental 

sedimentation 

Kg/m 2 /day 

Predicted incremental 

sedimentation without 

adjustment of critical 

shear stress parameters 

Predicted incremental 

sedimentation with 

adjustment of critical 

shear stress parameters 

Figure 10 presents the example maps of 

critical shear stress in South-West 

Singapore, whilst Table V presents an 

example of model performance against 

measured sediment trap data. 

0.02 

0.04 

< 0.01 

< 0.01 

0.04 

0.04 

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

SW Singapore for sediment released from dredging and reclamation operations.


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. 

Sediment settling velocity 

In order to reliably simulate the transport 

and fate of the fine material released from 

dredging and reclamation activities, it also 

proves necessary to divide the sediment 

spill into a number of sediment fractions. 

After testing of various options, 6 fractions 

(3 for reclamation fill and 3 for dredge 

material) have been found to provide a 

generally consistent compromise between 

model reliability and computational time, 

which is critical to the reporting schedule. 

In order to establish the characteristics of 

the 6 sediment fractions, fall velocity 

testing of the fine material present in the 

reclamation and dredge material is carried 

out on a regular basis via Owen tube tests. 

Fall velocity characteristics are typically 

updated on a monthly basis (separately for 

reclamation fill and dredged material), or 

when the daily control measurements in 

the sediment plume indicate a necessity for 

updating. An example of the Owen tube 

test results is provided in Figure 11. 

Execution of daily hindcast 

Based on the contractor’s activity information 

and calculated spill, the numerical spill 

hindcast is carried out on a daily basis for 

the actual reclamation operations. The result 

of the daily EMMP hindcast model are 

validated against the daily control samples 

taken in the sediment plumes originating 

from the reclamation. 

The daily hindcast is processed to allow 

direct comparison to the EQOs with the 

following key outputs: 

• Time series and tabulation of excess 

suspended sediment concentration at 

the various environmental receptors; 

• Maps of exceedences of 5, 10 and 

25 mg/l excess concentration; 

• Animations of concentration maps. 

UPDATING OF TOLERANCE LIMITS AND 

SPILL BUDGET 

As the spill budget is dependent on the 

tolerance limits of the various environmental 

receptors, it is critical that the reliability of 

these limits is confirmed at an early stage 

of the construction works, with continuous 

refinement carried out throughout the 

construction period. The tolerance limits are 

confirmed (or refined) based upon the 

results of quarterly habitat monitoring of 

key environmental indicators compared to 

the results of the sediment plume hindcast 

and sedimentation monitoring. 

Habitat monitoring 

Quarterly control habitat monitoring surveys 

are carried out to establish the status of the 

various marine habitats near the development 

site. The choice of survey locations is based 

upon 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 sediment 

plume forecast). 

For each survey station key indicators are 

identified and the survey sites laid out to 

facilitate exact replicate surveys. 

Coral habitat monitoring 

Coral surveys are primarily carried out using 

the Line Intercept Transect (LIT) method, as 

shown in Figure 12, which is recommended 

by the Global Coral Reef Monitoring Network 

(English et al. 1997, Hill et al. 2004) for 

quantification of the percentage cover of 

reef building corals, coral diversity, as well 

as other benthic life forms. The LIT 

methodology, which provides a good 

method for identification of mortalities of 

larger reef areas, is supplemented by exact 

repeat surveys of selected individual colonies,


Figure 12. LIT Coral habitat survey in Singapore. 

which is required to establish changes in 

stress levels or partial mortalities of colonies 

lying off the transect line. 

Example results from a repeat LIT survey 

close to the reclamation site at station 

CR07 are presented in Table VI. The LIT 

surveys indicate no significant change in 

reef characteristics as illustrated by the plot 

in Figure 13. 

For the exact repeat colony monitoring at 

the same site, 50% of the colonies showed 

some form of improvement in life form 

characteristics. 30% showed no change 

and 2 colonies (20%) were noted to have 

declined as a result of physical damage not 

directly attributable to the reclamation works. 

The sediment loading from the reclamation 

works at this site over the monitoring 

period is tabulated in Table VII. Comparison 

with the coral tolerance limits presented 

in Table I and Table II indicates that the 

sediment loading falls in the No Impact 

category. This is consistent with the 

recoded LIT and exact repeat results 

confirming, in this case, the applicability of 

the tolerance limits (at the No Impact level). 

Tolerance limits were therefore not updated 

and spill budget limits for the period after 

August 2006 were not adjusted. 

Seagrass monitoring 

Parameters used to assess the health of the 

seagrass areas include seagrass spatial 

distribution and composition, seagrass 

percent cover, seagrass diversity and 

evenness, seagrass biomass, sediment level 

and composition. 

Measures Analysis of Variance on Ranks, 

which is commonly used for comparison 

between two datasets, is used for the 

statistical analysis of sediment level and 

seagrass cover for comparison of the 

baseline and repeat surveys. Figure 14 shows 

an example from a seagrass bed close to the 

reclamation site. The mean seagrass cover 

documents a general increase between the 

baseline and the first Repeat Survey, but a 

decrease of approximately 20% documented 

between the first and second repeat. 

The corresponding sediment loading from 

the reclamation works at this site over the 

monitoring period is tabulated in Table VIII. 

This indicates the seagrass bed lie in the 

No-Impact zone, though a moderate decrease 

Table VI. Comparison of mean percent cover and standard deviation 

for the major benthic categories at CR07 

Baseline Repeat Survey 1 Repeat Survey 2 

Major Category August-05 May-06 August-06 

Mean Cover (%) STDEV Mean Cover (%) STDEV Mean Cover (%) STDEV 

Hard Coral 24.66 8.73 26.87 6.95 26.61 8.45 

Dead Coral 0.28 0.31 0.38 0.53 1.01 0.78 

Soft Coral 1.34 1.46 0.86 0.58 0.75 0.40 

Sponge 2.55 2.19 3.84 2.19 3.66 2.39 

Other Fauna 16.13 4.35 14.10 8.28 13.44 9.46 

Algae 19.93 8.01 27.87 8.76 30.36 12.86 

Rubble 32.72 16.21 21.86 8.62 22.02 9.51 

Rock 0.00 0.00 0.00 0.00 0.00 0.00 

Silt 0.00 0.00 1.94 2.50 1.63 2.16 

Sand 2.39 1.76 2.28 1.61 0.52 0.83 

Other 0.00 0.00 0.00 0.00 0.00 0.00


Figure 13. Changes in the mean percentage cover of 

the major benthic categories. 

in cover was identified by the habitat 

monitoring. In this case the hindcast 

models are conclusive in confirming that 

there is no direct flow of sediment from 

the reclamation area to this seagrass site, 

such that it can be firmly concluded that 

the decrease in seagrass cover is not 

attributable to the reclamation works. 

Tolerance limits were therefore not updated 

and spill budget limits for the period after 

August 2006 were not adjusted. The ability 

to isolate impacts from a development 

project from other third part or regional 

impacts is a major advantage of the feedback 

EMMP system adopted in Singapore. 

Table VII. Summary of percentage exceedence of suspended sediment 

and sedimentation loading over the coral reef monitoring site CR07 

presented in Table VI 

Date 

March April May June July August 

2006 2006 2006 2006 2006 2006 

% Exceedence 5 mg/l < 5% < 5% < 5% < 5% < 5% < 5% 

Nett sedimentation kg/m 2 /day < 0.05 < 0.05 < 0.05 < 0.05 < 0.05 < 0.05 

Table VIII. Summary of sedimentation loading over the seagrass monitoring 

sites presented in Figure 14 

March April May June July August 

Date 

2006 2006 2006 2006 2006 2006 

Nett sedimentation kg/m 2 /day < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 < 0.1 

Sedimentation monitoring 

Sediment traps are deployed on the reef 

crest, close to the LIT monitoring sites. 

These measurements document 

sedimentation levels along the reef area, 

which is used in part to validate the results 

of the sediment plume hindcast models 

(incremental sedimentation above 

background values) and in part to confirm 

tolerance limits. Sediment traps function as 

a measuring device for sedimentation on 

the reef area and are deployed in three 

replicates; each consisting of three 

cylindrical small tubes attached together. 

The theory and dimension of the sediment 

trap follows those recommended in the 

Survey Manual for Tropical Marine Resources 

(English et al, 1997). See Figure 15 for an 

impression of the sediment traps deployed. 

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

Baseline (Sep 05) 

Repeat 1 (May 06) 

Repeat 2 (Aug 06) 

To function reliably in the high sedimentation 

environment present in Singapore, sediment 

traps are recovered every fortnight. As a 

result of the large number of traps 

deployed in Singapore, ease of underwater 

service is important. This has lead DHI to 

develop a single point of attachment 

system that is operated by the single Allen 

screw seen in Figure 15. This system 

reduces the underwater service time by 

approximately 50%, improves the reliability 

of the data by reducing sediment loss 

during recovery and also reduces 

expenditures associated with cable ties and 

other consumables by approximately 50%.


Figure 16 presents an example of the 

absolute sedimentation rates close to the 

work area at the same reef monitoring 

presented in Table VI. This shows an 

average declining sedimentation rate 

between 0.08~0.11 kg/m 2 /day after 

baseline. The results presented in the figure 

indicate that no sedimentation impact at 

station CR07 during July and August falls 

within the No Impact limits. These results 

are consistent with the results of the 

sediment plume hindcast and habitat 

surveys (see Table VI for details of change in 

live coral cover at CR07) and fall within the 

EQOs for the project. 

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. 

Figure 16. Average sedimentation 

rates at station CR07. 

Online turbidity sensors 

Online turbidity sensors are deployed at key 

environmental receptors (coral reefs and 

intakes) in close proximity to the reclamation 

area in order to provide an initial response 

mechanism to any transients in suspended 

sediment concentrations and to provide 

supplementary validation data for the 

sediment plume hindcast models. 

The instruments are vertically secured to a 

platform deployed on the seabed, and held 

approximately 1 metre above the seabed. 

Data recorded is transformed from NTU to 

TSS via site-specific validation curves, which 

are updated on a weekly basis based on 

measurements taken during instrument 

servicing. The data is transmitted to a 

Data Information System that is used to 

disseminate all EMMP related data to the 

authorities and contractors. 

Average Sedimentation Rate [kg/m 2 /day] 

Average Sedimentation 

CR07 

Baseline 

10 Jul ‘06 

08 Aug ‘06 

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


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. 

Figure 17 presents a typical picture of the 

online sensor and an example of mean 

turbidity levels. The increase in turbidity 

levels observed in this example above the 

baseline mean results from sensor fouling, 

which is a significant problem in Singapore 

waters owing to high rates of algae 

growth, despite automatic sensor cleaning 

and weekly equipment service. 

As the turbidity measurements provide only 

a second level of EMMP response the 

reliability of the overall EMMP is not 

influenced by this fouling problem, which 

would otherwise be critical to management 

plans reliant purely on static monitoring. 

Other online instrumentation used for 

control monitoring include, for example, 

noise meters (Figure 18) and Acoustic 

Doppler Current Profilers (ADCP) (Figure 19). 

Noise meters are generally deployed at 

receptor sites (residential buildings and/or 

work sites) to document noise levels from 

the construction. ADCPs are deployed 

on the seabed for current and wave 

measurements. 

CONCLUSION 

The feedback approach to the Environmental 

Monitoring and Management of reclamation 

works summarised in Figure 20, which has 

been adopted in Singapore, provides a 

practical and reliable method for the 

pro-active management of potential 

environmental impacts resulting from 

reclamation works. 

The responsiveness of the system allows 

unexpected impacts to be mitigated prior 

to them becoming a serious threat to the 

environment. Importantly, the level of 

documentation provided ensures that 

developers and contractors are not exposed 

to unwarranted claims concerning 

environmental degradation as the EMMP 

approach allows full segregation of project 

impacts from other third party disturbances. 

In order to obtain the level of reliability and 

responsiveness required to meet strict EQOs 

relating to marine habitats and other 

environmental receptors in Singapore, several 

enhancements to various components of 

the EMMP have had to be realised. These 

include empirical methods for estimation of 

spill based upon sediment characteristics 

and type of operation, adapting sediment 

plume models to cater for complex dredging 

and reclamation schedules, plus specific 

adjustment of settling and re-suspension 

characteristics to cater for the complexities 

of reef morphology. 

The performance of the feedback EMMP in 

terms of meeting EQOs has been verified 

by habitat monitoring which also confirm 

adopted tolerance limits for corals and 

seagrass in high background suspended 

sediment and sedimentation environments 

such as those encountered in Singapore. 

The EMMP techniques presented here have 

also been successfully adopted for the 

environmental management of other 

dredging and reclamation projects in the 

region, including Bintulu and Kota Kinabalu, 

Malaysia and previously mentioned Bali Turtle 

Island, Indonesia. The EMMP techniques are 

thus becoming accepted best practice 

methodologies in the South East Asia Region.


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

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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.

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

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

PLANNING FOR THE FUTURE – 

GROUND IMPROVEMENT TRIALS 

AT THE PORT OF BRISBANE 

ABSTRACT 

The Port of Brisbane is located at the 

mouth of the Brisbane River at Fisherman 

Islands in Brisbane. In recent years, Port land 

has seen rapid development as a result of 

increased trade growth. This growth in the 

South East Queensland region is expected 

to continue for the next 25 years and 

beyond. The expansion and development 

of future Port land will see the reclamation 

of about 235 ha of existing tidal flats 

bounded by the FPE (Future Port Expansion) 

Seawall which was constructed to contain 

the reclamation. The reclamation will be 

carried out using channel maintenance 

dredging materials consisting of river muds 

capped with sand, as has been the past 

practice. The seabed conditions, however, 

are significantly different in the seawall area 

because of the high water table, in-situ 

compressible clays over 30 metres deep and 

the increased thickness of up to 7 to 9 metres 

of river muds to be deposited into the 

reclamation. 

Whilst historically it has taken about 10 years 

for reclaimed land to be available for 

commercial use, it is currently anticipated 

that this timeline will have to reduce to less 

than 5 years to meet demand. Therefore 

there is a critical need to accelerate the 

consolidation of the reclaimed land as 

traditional surcharging used at the Port in the 

past will not meet the future development 

timelines. In order to optimise various 

ground improvement techniques and assess 

their suitability for the local conditions, 

the Port of Brisbane Corporation invited 

expressions of interest from specialist 

ground improvement contractors for the 

design, supply and installation of ground 

improvement techniques to carry out full 

scale trials in the existing reclaimed land. 

Based on this process three internationally 

known contractors were appointed to 

conduct trials using wick drains and vacuum 

consolidation. Relevant performance criteria 

were established to assess performance 

throughout the design and installation 

phases to enable a successful Trialist and 

system or systems to be selected next year to 

start the broad-scale roll-out programme. 

Port of Brisbane Corporation and Coffey 

Geotechnics wish to acknowledge the 

professional and cooperative manner in which 

the three Trialists, namely, Van Oord, Boskalis 

Australia and Austress Menard have gone 

Above, Aerial view of the Port of Brisbane showing 

the reclamation areas including the trial areas. 

about their works during the design and 

installation phases. This paper was first 

presented at the Coasts & Ports 2007 

Conference, Melbourne, Australia in July 2007 

and is published here in an adapted version 

with permission. 

INTRODUCTION 

The Port of Brisbane is located at the mouth 

of the Brisbane River at Fisherman Islands. 

In recent years, the modern purpose-built 

Port has seen rapid development as a result 

of increased trade growth. This growth in 

the South East Queensland region is expected 

to continue for the next 25 years and 

beyond. The expansion and development 

of future Port land is critical to ensure that 

the Port’s facilities can expand at a rate to 

meet this growth. In 1999 the Port 

embarked on plans to investigate the 

expansion of a 235 ha area immediately 

to the east of the existing reclaimed area. 

In 2002, an Alliance Contract was formed 

between Port of Brisbane Corporation (PBC), 

geotechnical consultants Coffey Geotechnics 

(CG), coastal engineers WBM Oceanics, 

civil consultants Parsons Brinckerhoff and 

constructor Leighton Contractors, to deliver


Figure 1. Site layout. 

the Future Port Expansion (FPE) Seawall, 

a 4.6 km long perimeter rockwall which 

encloses the future expansion area. 

The Seawall construction, being the first stage 

in the expansion process, was completed in 

early 2005 (Ameratunga et al. 2003 and 

Andrews et al. 2005). PBC has since 

engaged CG as their geotechnical advisor 

for development of the reclamation areas. 

CREATION OF NEW PORT LANDS 

The Seawall allows for the containment of 

the progressive reclamation of about 235 ha 

of existing sub-tidal flats. The reclamation will 

be carried out using channel maintenance and 

berth dredging materials consisting of several 

metres of river mud capped off with sand. 

At the existing reclamation area (Figure 1) 

approximately 60 ha remains to be 

developed (in 2006-2007), but is at a more 

advanced state of filling and capping than 

the FPE area. The subsurface conditions in 

the seawall area and the existing reclamation 

area are significantly different from the 

developed areas (Figure 1), because of the 

high water table, in-situ compressible clays 

over 30 m thick and the increased thickness 

of up to 7 m to 9 m of river muds to be 

deposited into the reclamation. Generally 

consolidation timings for these undeveloped 

areas are predicted to be well in excess of 

50 years if surcharging is the only treatment 

employed, as has been past practice. 

Settlements in the range of 2.5 m to 4 m 

are also forecast. Given the pressures of 

creating additional usable Port land in time 

frames approximately half of those achieved 

in the past, a decision was taken that new 

techniques to speed up the consolidation 

process need to be employed to meet the 

land development timings. 

TREATMENTS TO SPEED UP LAND 

CREATION 

Clearly, filling the reclamation areas with 

sand sourced from the Moreton Bay 

channels instead of dredged mud would 

reduce the total thickness of soft clay and 

therefore minimise the impacts of filling the 

reclamation areas. 

However, as PBC must maintain navigable 

depths in its river channels and berths, 

some 500.000 m 3 of mud on average is 

dredged annually and must be disposed of 

in an environmentally friendly manner 

within the Port’s reclamation areas. 

Substantial research and investigation by PBC 

and CG into local and overseas practices of 

treatment of soft soil found that two main 

groupings of techniques are available to 

treat and improve the reclamation sediment 

and in-situ soils. 

Groupings of available ground 

treatments 

Apart from conventional surcharging, 

techniques to improve the ground can be 

grouped into two main areas, namely: 

1. Consolidation of the soft highly 

compressible soils by installing vertical 

drains or using vacuum consolidation 

with surcharging or; 

2. Improve, reinforce or stabilise the soils 

to reduce settlements and improve shear 

strength and stiffness. 

The suite of techniques falling under group 1 

comprises the installation of vertical drains, 

including sand drains or prefabricated vertical 

drains (PVDs), in a square or triangular 

pattern, generally spaced at 1 m to 2 m.


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. 

Vacuum consolidation is a process whereby 

a vacuum pressure is applied to an area 

already installed with pvd’s to potentially 

increase their effectiveness. Generally all 

techniques here require the application of a 

surcharge loading to squeeze water out of 

the soft clay soils. Such loading must be 

equal to or in excess of the service loading 

the developed land will be subjected to. 

In vacuum consolidation, the vacuum pressure 

applied contributes to the surcharge loading, 

and therefore actual surcharge heights are 

reduced. An additional important advantage 

of the vacuum is the isotropic nature of 

the vacuum pressure and the correlated 

improvement of the stability under preloading, 

reducing considerably the risk of slope 

failure resulting from the surcharge. 

Methods falling under group 2 include 

stone columns, piling the ground, mass 

mixing the soils, or local mixing of the soils 

over some form of grid by soil mixing. 

Where a grid of columns, piles, or in-situ 

mixed columns is used, a bridging mattress 

may be required across the site to transfer 

the surface loadings into the discrete soil 

supports. Significantly less or no surcharging 

is required with these techniques, and they 

generally provide a significant time saving. 

However, these treatments are typically 

more costly. In certain parts of the world, 

freezing of the ground can even be 

considered as a viable solution. 

Selection of Preferred Treatment 

Solutions 

Consideration was given to the most likely 

treatment technique applicable for use in a 

broad scale application. The conclusion was 

that the techniques available under group 1 

would most likely be best suited for broad 

scale treatment. In addition they would 

pose no boundary differences with present 

sites, where land consolidation techniques 

using surcharging alone have occurred. 

With relevance to the Port of Brisbane 

reclamation area, group 1 techniques i.e. 

PVDs, shaped as the preferred treatment 

over vacuum for mass application, primarily 

because of the necessity of a 15 m deep 

cut-off wall to mitigate the local site 

conditions (i.e. the occurrence of sandy 

layers) at the paddocks. Conversely, the 

vacuum consolidation process and solutions 

available under group 2 are considered to 

have merit in special situations such as 

edge treatments for berths or surcharge 

stability. The mixing of techniques from 

both groups, however, poses difficulties at 

transition zones which would need to be 

carefully considered. 

EXISTING GROUND CONDITIONS AND 

DESIGN PARAMETERS 

Target service loading and settlement 

criteria 

Historically, ground treatment for the Port’s 

developed existing reclamation area was 

designed for an in-service settlement 

criterion after construction of 150 mm in 

20 years. This criterion was associated with 

nominated design service loadings applied 

to the adopted finished design pavement 

levels as follows: 

• 36 kPa at marine terminal areas 

• 15 kPa at warehousing areas and road 

corridors. 

In planning for the future, however, PBC is 

considering increasing the design service 

loading of the marine terminals for future 

berths up to 50-60 kPa. Further, new land 

zoning of integrated logistics has been 

created, sandwiched between the marine 

terminals and warehousing zones, with an 

applicable design service loading of 36 kPa. 

This new zone covers areas previously 

gazetted as warehousing and subjected to 

a design service load of only 15 kPa. The 

increased service loadings, if adopted pose 

further challenges to the land development 

process in the new areas. Current thinking 

is that PBC may need to adopt two 

acceptance target service criteria in future 

as follows: 

• Where the total thickness of 

compressible clays and mud is less than 

a nominated thickness, say 10 m to 

15 m, retain 150 mm residual settlement 

in 20 years of service; 

• Where the total thickness exceeds the 

nominated thickness adopt an increased 

target of 250 mm in 20 years of service. 

Currently it is considered that a target of 

150 mm of residual settlement may not be 

feasible when using group 1 techniques,


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

particularly where soft compressible clay 

thicknesses including mud can total in 

excess of 30 metres. In such cases the 

creep settlement contribution from the 

deeper layers, which may be only slightly 

over-consolidated with respect to the 

design service loading, may be significant 

and may not be easily built out. 

Geological Units 

In the existing reclamation and FPE areas, 

four distinct geological units have been 

recognised 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 the 

Holocene unit underlying the study areas is 

shown in relative levels. The final design 

surface elevations of the paddocks vary 

from 6m to 9m RL. 

Recent sediments 

These materials generally consist of modern 

dune and beach deposits and dredged fill. 

The soil types consist of silt, clay and fine to 

Table I. Geological Units 

Unit 

Recent 

Holocene 

Pleistocene 

Tertiary 

Description 

coarse grained sand with interbedded 

layers of silt and clay. Shell layers may also 

be present. Material dredged from the river 

channels are deposited in the paddocks 

from a single point discharge, generating 

variable profiles in deposited materials. 

Holocene sediments 

Previous investigations have subdivided the 

Holocene sediments into an Upper and 

Lower layer of low strength silty clay with 

shell bands (“marine clay”) separated by a 

discontinuous layer of sand. The Upper 

Holocene layer generally consists of sand 

layers interspersed with layers of soft clays 

and silts. Sand layers or lenses are relatively 

few or absent within the Lower Holocene 

layer. 

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

This material may include fill, including dredged fill. 

Normally consolidated marine clay, silt and sand. 

Generally over-consolidated clay, sand and gravel. 

Weathered basalt bedrock of the Petrie Formation. 

Pleistocene sediments 

The Pleistocene layer is an older alluvial 

deposit below the Holocene deposit and 

comprises mainly over consolidated, very 

stiff to hard clays and medium dense to 

dense sands and gravel immediately 

overlying the bedrock. The compressibility 

of these materials is relatively low 

compared to the soft/firm clays of the 

Holocene deposit. 

Tertiary basalt 

The weathered basalt bedrock of the Petrie 

Formation underlies the site and is described 

as grey-green clay (extremely weathered 

basalt) grading downwards into dark grey 

to black, moderately to slightly weathered 

basalt.


Preliminary Geotechnical Parameters 

Based on initial ground investigations of the 

study areas an average set of geotechnical 

material parameters for the dredged mud 

and the Holocene clay was chosen. It also 

enabled the creation of basic soil models at 

the various study sites. These details were 

included in the documentation package 

to be issued to the various prospective 

Contractors to enable them to undertake 

system selection and preliminary designs 

and provide associated pricing applicable to 

their systems and solutions. Creating such 

details would enable CG and PBC to make 

fair comparisons between any proposals 

received for ground improvement works. 

These investigations also indicated low values 

for the coefficient of consolidation (c h 

), 

compared to previous results for the dredged 

mud layer and the Lower Holocene layer. 

The c h 

relates to the dissipation rate of 

water from the clay and therefore together 

with the clay thickness and presence of 

sand layers determines the consolidation 

time. Settlement information from other 

older reclamation paddocks tends to indicate 

higher rates of dissipation, likely to be due 

to greater distribution of sand lenses within 

the dredged mud layer. 

METHODOLOGY FOR SELECTION OF 

OPTIMAL GROUND IMPROVEMENT 

SYSTEM 

After due consideration of all known 

available ground treatment techniques, 

PBC decided to invite Expressions of 

Interest (EOI) from specialist ground 

improvement Contractors, either local or 

from overseas, interested in providing 

services for the design, supply, installation 

and monitoring of suitable specialist 

ground improvement systems to the 

existing reclamation areas at the Port of 

Brisbane. 

Expressions of interest 

The EOI document indicated that such systems 

should enable the reclaimed areas to be 

developed by the Port in a considerably 

shorter time frame than that achieved by 

surcharging alone, providing acceptable 

in-service settlements and at the same time 

resulting in cost effective and optimum 

treatment solutions. Whilst the EOI 

document permitted any and all solutions, 

it did indicate that vertical drains including 

PVDs and sand drains were likely solutions. 

Sand drains were included on account of 

the ready availability of sand at the Port 

sourced from the bay shipping channels. 

To enable the actual performance and 

cost of any proposed ground treatment 

solution put forward by Contractors to 

be evaluated, the EOI document proposed 

that one or two suitably qualified short 

listed Contractors would be selected and 

allowed to trial their systems on a four (4) 

hectare site. The documentation sought 

that Contractors provide preliminary costed 

designs and forecasts within their proposals 

for their systems of ground improvement 

based on the initial geotechnical parameters 

and basic soil models provided by 

CG and PBC and other relevant information 

contained in the EOI documentation. 

Assessment of proposals received 

At the closing of EOI submissions, eight 

proposals were received. Proposals were 

received from both local and overseas 

Contractors. Overseas Contractors from 

The Netherlands, Germany, France and 

SE Asia were keen to offer their respective 

expertise. The submissions received 

generally supported the use of PVDs as 

the preferred solution for the Port sites. 

The EOI document contained six selection 

criteria that Contractors were advised 

would have their proposals assessed 

against. These criteria are listed in Table II. 

PBC and CG assessed all Proposals received 

by scoring them against the selection 

criteria. This resulted in the short-listing 

of three preferred proposals. These three 

submissions could not be substantially 

separated in terms of the selection criteria, 

with all three offering PVD solutions. 

Two of the three Contractors offered 

vacuum consolidation systems as possible 

solutions in addition to PVDs. 

Trials scheme adopted 

PBC decided that there was considerable 

merit in trialling all three Contractors rather 

than further reducing the number of trials 

and trialists from 3 to 2 or even to 1. 

Also, plans to develop future Berths 11 

and 12 and associated backup lands further 

advanced as the EOI process progressed. 

Accordingly PBC decided to expand the 

trials scheme previously proposed to include 

three trialists and trial PVDs over 3 sites 

of 3 ha each with a further special edge 

area of 2.5 ha set aside for a vacuum 

consolidation trial. The successful trialists 

included three international companies: 

Van Oord, Boskalis Australia and Austress 

Menard (Menard). Contracts were 

subsequently successfully negotiated with 

each Trialist. 

In addition, a scheme of assessment for the 

Trials during the design and construction 

phase was established and agreed with all 

three trialists. These criteria are largely 

based on expanding upon the criteria 

contained in Table II. It is further proposed 

to place a control or reference surcharge 

embankment, fully instrumented but 

without PVDs, for performance comparison 

purposes. 

TRIALS PROGRAMME 

A 3 ha site was provided to each Trialist for 

PVD installation. Each Trialist was given the 

opportunity to propose a trial scheme 

which would generally enable maximum 

learnings for each. The design proposals 

put forward by the companies have shown a 

large degree of thought and individualism. 

The trials utilise several different PVDs, 

varying both in core and filter type and a 

range of different spacings. 

Boskalis is also trialling its BeauDrain-S 

vacuum consolidation system, which is an 

Australian first. Menard is trialling their 

proprietary vacuum consolidation system 

along a special edge site. The system 

proposed includes a cut-off wall around the 

perimeter of the site to cut off the effects 

of 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 the 

Ballina By-Pass Project, located in New 

South Wales, Australia.


Table II. EOI assessment criteria 

Criteria 

Overall Price 

Past experience as designer & installer of 

ground improvement systems 

Ability to meet or exceed design criteria 

and timings nominated 

Proponent’s Financial capacity 

Warranties or Performance Guarantees 

QA, Environmental, and Loss Control systems 

Issues 

One of the key factors in the assessment will be the all-up price for the ground 

improvement treatment system, i.e. including all surcharging costs, monitoring, etc. 

A Proponent who has a demonstrated history as a proven ground improvement specialist 

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 personnel 

nominated to work on the project(s). 

Proponents who can deliver the works to PBC’s preferred timelines whilst meeting the set 

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. 

Proponents will need to demonstrate an adequate financial capacity to undertake the 

project to be ranked highly against this criterion. 

Proponents who submit warranties or performance guarantees to deliver the areas within 

the residual settlement criteria nominated under the nominated loadings and design 

criteria will be highly ranked. 

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 progress 

As at June 2007, Boskalis Australia had 

completed installation of all wick drains and 

the BeauDrain-S system (Figures 3 and 4). 

Van Oord had also completed all PVD 

installation works (Figure 5). After rather 

extensive preparatory works, including 

constructing the 15 metre deep perimeter 

vacuum cutoff wall, Austress Menard 

completed wick drain installation to all trial 

areas in May. The vacuum consolidation 

system installation including membrane, 

pipework and pumps was completed and 

the system commissioned in June 2007 

(Figure 6). 

The aerial photo (Figure 7) 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. The black L is the 

vacuum trial area with (black) membrane, 

pipework and pumps installed. Behind this 

is the white sand drainage layer placed over 

the wick drain trial areas which extend up 

to the future road alignment. Surcharge 

placement across both the wick drain and 

vacuum trial areas is currently underway. 

The 15 m deep cutoff wall was installed 

around the perimeter of the L. 

Given the expanded area of the trials and 

increased loading parameters, some 1.5 million 

cubic metres of surcharge is required to be 

placed following the contractors’ installation 

works. Installation of an extensive number 

and type of monitoring instruments 

including piezometers, extensometers, deep 

settlement plates, load cells and inclinometers 

is now complete. Surface settlement 

markers on a 25 m grid are also in place. 

The common view of the trialists is that 

meaningful interpretations of the measured 

performances of each trial area will be able 

to 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 the 

results reviewed by CG experts, including 

Prof Harry Poulos, and externally by an 

appropriate expert. PBC is currently sourcing 

a suitable data capture and presentation 

software system for use during the Trials. 

Trialists have submitted samples of all PVD 

types being used in the Trials to enable 

relevant laboratory testing of the PVDs to 

be undertaken, including horizontal and 

vertical flow capacities in unkinked and 

kinked states. Kinking of PVDs is a possible 

outcome with certain PVD cores subjected 

to large settlements. 

Anticipated outcomes 

PBC and CG expect to achieve the following 

outcomes from the trials: 

1. Identify the effectiveness of PVDs for 

local site conditions, including thickness 

and depth of dredged mud and soft 

clays plus natural drainage conditions 

2. Identify the performance of PVDs for 

different spacings in relation to local 

conditions 

3. Identify differences in PVD performance 

and cost implications 

4. Verify consolidation times, and required 

surcharge loadings using PVDs and using 

vacuum consolidation 

5. Identify performance of Contractors in 

relation to design and construction. 

As regards comparison of design and 

construction capabilities of three world-class 

contractors, as the size of the trials has 

expanded, the 6 months results are not 

expected to be available before the middle 

of 2008. 

CONCLUSIONS 

PBC identified that no single optimum solution 

existed to accelerate the consolidation of 

soils and dredged sediment to develop land 

within the future Port reclamation areas. 

Indeed several techniques are available and 

all have their advantages and disadvantages 

in relation to time, cost and performance. 

By calling and receiving expressions of 

interest from specialist contractors both 

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. 

locally and overseas and subsequently 

engaging three world-class contractors to 

undertake an extensive suite of trials, 

PBC believes it will arrive at an optimum 

solution or series of working solutions. 

These solutions will be able to be utilized 

to develop large tracks of reclaimed land 

suitable for Port industries and meet a 

range of future time demands. 

Whilst undertaking trials over an area of 

11.5 ha looks excessive, it needs to be 

realized that this only equates to less than 

4% of the land areas to be developed 

(see Figure 1). It is considered that the 

additional costs associated in undertaking 

the trials, such as extra field and laboratory 

testing and intense performance monitoring, 

will be recovered in the first couple of years 

of optimized broad scale treatment rollout. 

Further, it will provide for a significant 

degree of confidence in land availability 

timelines going forward that can be taken 

with confidence to the market place. 

Implementing results of the Trials will allow 

quality land parcelling for development that 

can be released in a staged, timely manner. 

PBC is aware and currently addressing the 

logistical issues in instrumenting numerous 

large trial sites, data capture, processing 

and presentation and the placement of 

1.5 million cubic metres of surcharge in 

an obstacle intense area. 

The Trials have already generated significant 

interest from industry, both Client and 

Contractor. 

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.

Panama Canal Atlantic Entrance Expansion Project 27 


PANAMA CANAL ATLANTIC ENTRANCE 

EXPANSION PROJECT 

ABSTRACT 

The commercial importance of the Panama 

Canal for over some 90 years cannot be 

overstated. Vessels transiting through the 

Canal between the Atlantic to Pacific Oceans 

save an enormous amount of time bringing 

goods to market. However, given the 

increasing size of cargo vessels, known as 

post-Panamax, and the longer wait times 

for slots to transit the Canal, the need for 

widening and deepening the Canal became 

obvious. The Autoridad del Canal de Panama 

(Panama Canal Authority; ACP) is responsible 

for all dredging operations in the Canal 

and at the Atlantic and Pacific Entrance 

Channels. Usually dredging activities are 

carried out by its own fleet of dredgers, 

including the hydraulic dredger Mindi and 

dipper dredger Rialto M. Christensen for 

deepening and maintaining the waterway. 

However, considering the scope of the 

work, the ACP decided to offer an 

international tender for deepening and 

widening the Entrance Channels. This 

proved to be a good choice as one of the 

most serious challenges to any dredging 

operation in the Canal is that vessels 

transiting the Canal must always have 

priority. In fact during the execution of this 

project, at least half of the channel width 

had to remain available for transiting vessels 

at all times. With these requirements in 

mind, the ACP opted to employ international 

state-of-the-art dredging equipment to 

facilitate the dredging operations necessary 

to keep the Canal functioning efficiently. 

The large capacity of these dredging ships 

plus their self-propelling capability allowed 

them to avoid obstructing transiting vessels 

and to expedite the work. 

INTRODUCTION 

The Panama Canal, which first opened in 

1915, is an 80 km long waterway between 

the Atlantic and Pacific Oceans. The Canal 

was cut through the narrowest part of the 

isthmus in Central America that connects 

North and South America eliminating the 

long and treacherous voyage around South 

America. The importance of the Panama 

Canal for the world economy cannot be 

emphasised enough. Every year more than 

13.000 ships are transiting the Canal, 

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. 

ranging from private yachts to luxury cruisers 

to Panamax cargo vessels. The commercial 

transportation activities via the Canal 

represent approximately 5% of the world’s 

trade 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’s 

economic importance this situation is 

unacceptable and therefore plans have been 

adopted to widen and deepen the Canal. 

The Panama Canal consists in total of three 

sets of locks; the Gatún locks at the Atlantic 

coast and the Pedro Miguel and Miraflores 

Locks at the Pacific coast (Figure 1). The entity 

of the Government of the Republic of Panama 

in charge of the operation, administration, 

management, maintenance and modernisation 

of the Canal is the Autoridad del Canal de 

Panamá (Panama Canal Authority; ACP). 

All operations within the boundaries of the 

Panama Canal are managed by the ACP. 

The entrance channel approaching the 

outer locks (Gatún Locks at the Atlantic 

side 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 launched 

international tenders for “Deepening of the


Figure 1. Location map of the Panama Canal 

and the area to be dredged. 

Pacific Entrance” and the “Deepening 

and Widening of the Atlantic Entrance” of 

the Panama Canal. On the 22 July 2004 

Jan De Nul NV received the Notice of Award 

for the Deepening and Widening of the 

Atlantic Entrance. 

The contract works included the dredging 

at the Atlantic Entrance Reach station 

–1K + 036 m up to the Gatún Locks North 

Approach Reach station 10K + 250 m. 

The navigation channel of the Atlantic 

Entrance, as from the outer breakwater till 

the locks, over a length of 11.286 km had 

to be dredged till –14.2 m and the eastern 

side of the Entrance Channel had to be 

widened with 22.86 m up to 99.6 m. 

After the dredging, the total width of the 

Entrance Channel would become 198.12 m 

with 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 volume 

of some 2.360.000 m 3 had to be removed 

and placed at the designated disposal areas. 

CHALLENGES 

Several boundaries were contractually 

applicable that presented significant 

challenges to the dredging operation. 

For instance, the Contract stipulated that 

the dredging works were to be completed 

within a period of 24 months as from the 

Notice to Proceed. In addition, under no 

circumstances could the transit of vessels 

be obstructed and strict limitations both in 

place and time were imposed upon the 

Contractor for the duration of the Contract. 

Traffic in transit 

Everyday a convoy of southbound ships 

(primarily Panamax vessels) starts its voyage 

to transit the Panama Canal, leaving the 

anchor areas around 6 in the morning at the 

Atlantic side. As from 6.00 am until approximately 

noontime vessels sail continuously 

through the dredging area towards the Gatún 

Locks. At the same time the northbound 

ships (also Panamax vessels) start transiting 

the Miraflores Locks at the Pacific Side. These 

convoys cross each other within the Gatún 

Lake. Around 1 pm (13.00) the first northbound 

vessels start to transit the Gatún 

Locks and sail towards the Atlantic Ocean. 

Normally around 8 pm (20.00) the 

northbound convoy has transited the Canal. 

Traffic, however, does not stop at 8 pm. 

During the night is the time for the smaller 

ships (small bulk carriers, tugboats, yachts 

and such) to transit the Canal. In view of 

the daily schedule of the convoys in transit, 

ACP ruled out the presence of dredging 

equipment in the areas 10K + 250 to 

8K + 400 (the narrowest part of the 

Atlantic Entrance, close to the Gatún Locks) 

from 5.00 am to 8.00 pm. Additionally, 

during the execution of the dredging 

works, at least half of the channel width 

had to remain available for transiting 

vessels at all times. 

Communications 

In order to optimise communications between 

the dredging vessels and the transiting vessels, 

ACP ordered the presence of an ACP pilot 

onboard the main dredging units (trailing 

hopper dredgers and a cutter suction 

dredger) and a first mate of ACP onboard 

of all of the auxiliary equipment such as 

multicast and tugboats. 

Close coordination with all involved 

departments within ACP was crucial for the 

smooth execution of the project. The Port 

captains at Cristobal Port, the Pilot 

department, the Survey department and 

the Safety and Environmental departments 

were involved at each stage of the project 

and had to be informed about the progress 

and the interfaces of the dredging project 

on regular basis. 

Soil conditions 

A particular challenge for the successful 

execution of any project in the Panama 

Canal is the ever- changing soil conditions. 

In order to define the soil conditions of this 

particular section to be deepened and 

widened, an extensive soil investigation was 

carried out. This included geo-electrical


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. 

surveys, side-scan sonar surveys, a resistivity 

study and a bore-hole campaign. All of 

these were performed during the tender 

period by the interested Contractors. In the 

end, the diversity of material to be dredged 

at the Atlantic side ranged from silt, clay 

and fine sand to medium and hard rock 

(siltstone type Gatún). 

The contracts for the dredging of the 

Atlantic and Pacific Approaches were the 

first major dredging contracts, other than 

a sporadic maintenance contract, for which 

ACP had issued an international tender. 

Up to then, ACP had performed maintenance 

and capital dredging works within the Canal 

utilising its own equipment, mainly the 

64 year old cutter suction dredger Mindi 

and the 30 year old mechanical dipper 

dredger Rialto M. Christensen (Figure 2). 

The first phase 

The execution of the works started 

immediately with the trailing suction hopper 

dredger Francesco di Giorgio, a dredger 

with a 4400 m 3 hopper capacity and a total 

installed power of 6330 kW (Figure 3). 

The TSHD Francesco di Giorgio was 

constructed at the Astillero de Gijon – IZAR 

in 2003 and is equipped with 2 electrichydraulic 

Schottel rudder propellers of 

2150 kW and a Schottel transverse bowthruster 

system of 550 kW. These latter 

installations ensure a very high maneuverability 

of the dredging vessel, which was very 

important during the operations in the 

Canal, particularly near the locks, because 

of 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 at 

the Northwest Breakwater Disposal Area 

(offshore from the Northern breakwater). 

Some soft material was also removed 

between stations 4K + 000 and 8K + 400. 

However, the steep slopes and hard material 

required further use of a cutter suction 

dredger in that area. 

During this phase a total volume of 

approximately 1.000.000 m 3 was dredged 

after which the Francesco di Giorgio was 

temporarily demobilised from the site. 

As was expected, because of the high 

manoeuverability of this dredger, no 

problems with the transiting vessels were 

encountered during the execution of the 

first phase. 

EXECUTION OF THE DEEPENING AND 

WIDENING OF THE ATLANTIC ENTRANCE 

After submission of the insurance certificates, 

the Quality Control Plan, the Method 

Statements, the Work Schedule and the 

Dredging Execution Plan and their approval, 

ACP issued the Order to Proceed on 

October 2 2004. 

Figure 3. TSHD Francesco di Giorgio working at 

Atlantic Entrance with continuous freight traffic.

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

The second phase 

While the dredging operations with the 

hopper dredger were going on, preparation 

for the second phase of the works was 

started. A cutter suction dredger (CSD) had 

to be used to remove the medium to hard 

Gatún rock in the Entrance Channel and to 

dredge the steep slopes. The hard material 

to be removed was mainly situated in the 

southern part of the Entrance Channel 

(8K + 400 to 10K + 250) and at the eastern 

side. Additionally some hard spots between 

3K + 500 and 4K + 000 were encountered 

in the middle of the canal. 

In total three inland disposal areas for 

the materials of the CSD were prepared: 

Davis Landing Disposal Area, Sherman 

Center Disposal Area and Telfers Inland 

Disposal Area. Davis Landing Disposal Area 

is situated at the eastern side of the Canal 

between 9K + 100 and 9K + 500. 

The distance between the middle of the Canal 

and Davis is approx. 250 m. The disposal 

capacity of this area was approx. 150.000 m 3 . 

Telfers Inland Disposal Area, also situated 

at the eastern side of the Canal between 

5K + 000 and 5K + 800, is situated at a 

distance of approximately 500 m from the 

Canal axis. Sherman Center, with a disposal 

capacity of approximately 650.000 m 3 , 

is situated at the western side of the Canal 

at a distance of 200 m from the Canal axis. 

To accomplish the task, the self-propelled 

CSD JFJ De Nul was mobilised and came 

over from Russia (Figure 4). This vessel, with 

a total installed diesel power of 27,240 kW, 

was built by IHC Holland in 2003. The fact 

that the cutter is self-propelled proved to 

be an invaluable asset for the successful 

execution of the Project. Time lost because 

of continuous vessel traffic could be 

substantially compensated for because of 

the efficient shifting of the CSD back to her 

position. 

The JFJ De Nul arrived at the Port of Cristobal, 

Panama in mid January 2005. The challenge 

of the rigorous restrictions of ACP regarding 

working hours at the southern part of the 

Entrance Channel (from 8.00 pm till 5.00 am 

between 8K + 400 and 10K + 250) quickly 

became obvious. As stated earlier, the 

self-manoeuvering capability of the CSD 

proved to be an asset. In addition, the 

good communication and interaction 

between the ACP pilots (both onboard the 

JFJ De Nul and onboard the transiting 

vessels) and the crew, meant that the 

effective operation time could be improved 

considerably, even though the restrictions 

of the minimum availability of half the 

Canal for traffic and the priority for the 

transiting vessels was always observed 

(Figure 5). 

Dredging at the eastern side commenced 

and the material was pumped via 500 m 

floating pipes and shore pipes to the 

Davis Disposal Area and the Telfers Inland 

Disposal Area. Because of the limited size 

of the Davis Disposal Area and the location 

of the Telfers Inland Disposal Area, part of 

the material from the eastern side had to 

be pumped towards the Sherman Center 

Disposal Area on the opposite bank as well. 

For this purpose a sinker pipeline was placed 

on the bed of the Panama Canal in an area 

that was previously dredged, which ensured 

that it would avoid being a hindrance to the 

transiting vessels. The installation of the

Panama Canal Atlantic Entrance Expansion Project 31 

Figure 5. CSD JFJ De Nul working at 

Atlantic Entrance simultaneously 

with transiting vessels. 

sinker pipeline was carefully prepared and 

ultimately done during a traffic window 

(2-3 hours at noontime) without disruption 

of traffic (Figure 6). 

After the widening of the eastern side the 

CSD JFJ De Nul was sent to deepen the 

western side of the Canal. Most of the 

material collected there was pumped into 

Sherman Center Disposal Area. In the centre 

of the canal some hard material was precut 

for later removal by a trailing hopper dredger. 

Owing to the presence of siltstone (Gatún 

formation), the contract specifications 

prescribed a slope of 1V : 1H at the eastern 

side of the Canal between 8K + 400 and 10K 

+ 250. Nevertheless between 9K + 800 and 

10K + 250 soft plastic clay was encountered 

and the 1V : 1H slope proved unstable. In this 

section additional shore protection was 

placed in order to achieve a stable slope. 

In total a volume of 590 m 3 of revetment 

material “Matacan 12-24 inch” was placed 

by dry equipment to protect the slope. 

The cutter operations took in total around 

two months with a total volume of 

approximately 1.300.000 m 3 being dredged. 

During the whole execution period everything 

was done to minimise interference with the 

traffic. As a result none of the transiting 

vessels ran into delays because of the 

ongoing dredging operations. 

Francesco di Giorgio was remobilised to the 

job by mid March 2005. At the same time a 

sweeping operation was performed in 

order to remove the last high spots. 

At the end of the Original Contract, taking 

advantage of the presence of this TSHD 

and convinced of the possibilities of the 

vessel to work in confined areas, ACP 

decided to issue a Variation Order to carry 

out some maintenance dredging in front of 

the Gatún Locks (10K + 250 – 10K + 750). 

After the official out-survey was carried 

out and further approval of all involved 

departments (Port Captain, ACP Contracting 

Division, ACP Survey Department, ACP Pilots 

and so on) had been obtained, the Final 

Acceptance of the Contract on May 12, 2005 

was received. The execution period took 

only slightly over 7 months instead of the 

24 months as foreseen in the tender 

documents. The decision to work with 

modern state-of-the-art vessels proved to be 

correct choice for both Client and Contractor. 

CONCLUSIONS 

Working in such a dynamic environment as 

the Panama Canal, where the first and only 

priority is to get the transiting vessels swiftly 

and safely to the other end of the Canal, 

proved to be a major challenge for the 

Contractor. The fact that under no 

circumstances could the transit of vessels be 

obstructed meant that strict limitations both 

in place and time were imposed upon the 

Contractor for the duration of the Contract. 

This challenge could only be converted into 

a successful project by applying the highest 

quality standards and utilising modern stateof-the-art 

vessels. As a result none of the 

transiting vessels ran into delays because of 

the ongoing dredging operations nor were 

the dredging operations hindered by the 

transiting vessels. In the end, because of 

this, the execution period for widening and 

deepening the Canal took only slightly over 

7 months, far less than the 24 months 

allowed for in the tender documents. 

For the final clean up and for the removal 

of the material that had been precut, the 

Figure 6. Sinker operations by 

means of a Multicat.


BOOKS/PERIODICALS REVIEWED 

The second example concerns the radioactive 

distribution of high-level radioactive waste. 

How does this distribute over the years through the 

groundwater flow? Also here the modelling has to 

take 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 whole 

area concerned. 

Useless Arithmetic. Why Environmental Scientists 

Can’t Predict the Future. 

BY ORRIN H. PILKEY & LINDA PILKEY-JARVIS 

Published 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 bit 

awkward to receive a request to write a critical note 

on a book with such a provocative title. Still it was 

also a challenge not to look at the book too much 

through the eyes of an engineer. 

When I saw the title of the book I had to think of one 

of the statements in my PhD thesis written in 1987: 

Modelling is the attempt to describe reality without 

pretending to be reality. With this in mind the reader 

can approach the book in the right perspective. 

The authors are both scientists. Orrin H. Pilkey is the 

James B. Duke Professor Emeritus of Geology and 

Director of the Program for the Study of Developed 

Shorelines at Duke University's Nicholas School of the 

Environment. Linda Pilkey-Jarvis is a geologist in the 

State of Washington's Department of Ecology, where 

she 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 were 

determined, but this did not lead to a stable situation. 

The reality was much more complicated than the 

models assumed. In addition, the models required a 

good description of the starting situation, which in 

fact was not available. Even with the perfect model 

the rule applies: “garbage in, garbage out”. 

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 human 

interference is difficult to determine. There are too 

many parameters involved of which many are almost 

impossible to ascertain. 

As a scientist and an engineer I do believe that it is 

possible to create models for many physical 

phenomena. In engineering we already have many 

models that have proven their usefulness. The fact 

that we can do strength and stiffness calculations and 

predictions for many systems and constructions, like 

bridges, without these constructions to fail, proves 

that there are many models that are reliable. We can 

send people to the moon, based on mathematical 

models. 

One of the main reasons for rejecting the use of 

mathematical models, the authors say, is the lack of 

knowledge of initial conditions, confirming the 

statement of “garbage in, garbage out”. 

After reading the book, my opinion about the use of 

mathematical models has not changed. The book 

might put mathematical modelling in another 

perspective; the use of mathematical models to 

predict the future in any discipline depends on the 

modelling itself and on the input. If one of them is 

not accurate or complete, the results will be doubtful. 

This does not, however, mean we should stop creating 

more and more advanced models. One day we will be 

able to predict things that we cannot predict now. 

But we should stand with both our feet on the ground 

and realize which models are ready for use in the real 

world and which models should be kept in the 

scientist’s environment for further development. 

The book is available from Columbia University Press 

at http://www.columbia.edu/cu/cup 

DR.IR. S.A. MIEDEMA

Seminars/Conferences/Events 33 

SEMINARS/CONFERENCES/EVENTS 

4 th International Conference on Port 

Development and Coastal Environment (PDCE) 

VARNA, BULGARIA 

SEPTEMBER 25-28, 2007 

Conference on Contract Management 

for Land Reclamation 

LONDON, UK 

OCTOBER 23-24, 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: office@bsca.bg 

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

BSCA website: www.bsc.bg 

23 rd Annual International Conference on 

Contaminated Soils, Sediments and Water 

UNIVERSITY OF MASSACHUSETTS, 

AMHERST, MASSACHUSETTS, USA 

OCTOBER 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 

Email: dleonard@schoolph.umass.edu.com 

or info@UMassSoils.com 

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 ceda@dredging.org 

www.dcm-conference.org or Richard Hart, 

Tel.: +44 1460 259 776 

E-mail: richard.hart@event-logistics.co.uk 

Port & Terminal Technology 2007 

ANTWERP, BELGIUM 

OCTOBER 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


Europort Maritime 

AHOY’ ROTTERDAM, THE NETHERLANDS 

NOVEMBER 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 

Email: e.vanderloo@ahoy.nl 

Mr. J. Teunisse, Senior Account Manager 

Tel.: +31 10 293 32 07 

Email: j.teunisse@ahoy.nl 

www.europortmaritime.nl 

CEDA Dredging Days 2007 

AHOY’ ROTTERDAM, THE NETHERLANDS 

NOVEMBER 7-9, 2007 

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 

Email: ceda@dredging.org 

or the Dredging Days website: www.dredgingdays.org 

37 th Dredging Engineering Short Course 

CENTER FOR DREDGING STUDIES, 

TEXAS A&M UNIVERSITY COLLEGE STATION, 

TEXAS USA 

JANUARY 7-11, 2008 

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 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 

Email: r-randall@tamu.edu 

www.oceaneng.civil.tamu.edu 

PIANC COPEDEC VII 

DUBAI UNITED ARAB EMIRATES 

FEBRUARY 24-28, 2008 

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 

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

Seminars/Conferences/Events 35 

CALL FOR PAPERS 

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 

Email: Copedec@lhi.lk 

www.pianc-aipcn.org 

Oceanology International 2008 

LONDON, UK 

MARCH 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 Meeting 

Western Dredging Association 

INTERCONTINENTAL RIO HOTEL 

RIO DE JANERIO, BRAZIL 

DECEMBER 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


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 

Email: rkm@bbl-inc.com 

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 

Email: Terpasa@uol.com.br 

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 

Email: r-randall@tamu.edu 

CEDA Dredging Days 2008 

CONFERENCE CENTRE ‘T ELZENVELD 

ANTWERP, BELGIUM 

OCTOBER 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 multidisciplinary 

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 

Email: rita.peys@ti.kviv.be 

www.dredgingdays.org/20008

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 

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 info@iadc-dredging.com 

I www.iadc-dredging.com 

I www.terra-et-aqua.com 

International Association of Dredging Companies 

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. 

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).

International Association of Dredging Companies

terraet aqua editorial - Dredging Engineering Research Laboratory

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