international journal on public works, ports & waterways ... · front cover: one of six...

INTERNATIONAL ASSOCIATION OF DREDGING COMPANIES

International Journal on Public Works, Ports & Waterways Developments

Number 66 - March 1997

Terra et Aqua – Number 66 – March 1997

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 thedevelopment of ports and waterways, and in particular, the associated dredging work.The name Terra et Aqua is a registered trademark.

EditorMarsha R. Cohen

Editorial Advisory CommitteeH. van Diepen, ChairmanJ. Boeter H. de Vlieger E.A.M. StraussH. Fiers C. Paris Solas P.G. RolandP.J.A. Hamburger

Editorial AddressTerra et AquaDuinweg 212585 JV The Hague, The NetherlandsTel. 31 (70) 352 3334Fax 31 (70) 351 2654

Please address inquiries to the editor.Articles in Terra et Aqua do not necessarily reflect the opinion of the IADC Board or of individual members.

© 1997 IADC, The NetherlandsAll 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.

Front cover:One of six cutterheads available to dredge the extremely hard layers of Copenhagen Limestone in thetunnel trench, a part of the Øresund Fixed Link tunnel-bridge which will connect Denmark and Sweden (see page 16).

IADCDuinweg 212585 JV The Hague, The NetherlandsTel. 31 (70) 352 3334Fax 31 (70) 351 2654 International Association of Dredging Companies

2 Editorial

3 Dredged Material Disposal in the Sea

T. Neville Burt and Carolyn A. Fletcher

International conventions regulate the disposal of dredged material in the sea, but nationaland regional approaches and interpretations vary widely. An analysis.

14 Environmental Aspects of Dredging; Guide 2: Conventions, Codes, andConditions, Marine Disposal and Land Disposal

The second guide in the IADC/CEDA series on a broad range of environmental dredgingissues describes the legislation on the disposal of dredged material at sea and on land.

16 The Øresund Fixed Link: Dredging and Reclamation

Maurice de Kok, Wouter Dirks and Rienk Hessels

To build the 16 km long bridge-tunnel link from Denmark to Sweden requires thedredging of extremely hard layers of limestone, often in extreme weather conditions, withstrictly controlled spillage limitations.

25 Books/Periodicals Reviewed

Proceedings of several conference are reviewed as well as two brand new editions ofstandard dredging “bibles” – Turner’s Fundamentals of Hydraulic Dredging and Dredging.A Handbook for Engineers by Bray, Bates and Land.

30 Seminars/Conferences/Events

Courses and conferences in Vietnam and Indonesia, the UK and The Netherlands, andNew Zealand.


CO N T E N T S


2

EDITORIAL

The two important international conventions governing the disposal of dredgedmaterial at sea and on land have been revised recently – the OSPAR Conventionin 1992 and the London Convention 1972 in 1996. On November 7 1996 the “Draft1996 Protocol to the Convention on the Prevention of Marine Pollution by Dump-ing of Wastes and Other Matter, 1972” was approved by the Drafting Committeeof the International Maritime Organization. It is presently being distributed tocountries for ratification.

In this context, the article by Neville Burt and Caroline Fletcher (page 3)provides a useful and timely commentary on the international conventions andtheir applications. This subject is further elaborated in their recently publishedbook, which is part of the IADC/CEDA series on “Environmental Aspects ofDredging”, Guide 2: Conventions, Codes and Conditions; Marine Disposal andLand Disposal. A review of this two part guide follows on pages 14-15 of this issue.The third guide in the series about pre-dredging trials is soon to be published thisspring.

In fact, through their involvement with Terra et Aqua, the Editorial AdvisoryCommittee of the IADC has become increasingly supportive of other publishingventures pertinent to the dredging industry. These include a newly updated fourthedition of Dredging for Development published in cooperation with IAPH (due inMarch) and a new book entitled Dredging Vessels of the World published byOilfield Publications Ltd.

All the above-mentioned books, as well as many others, are available by fillingin the Publications form insert and sending it to the IADC Secretariat inThe Hague.

Marsha R. CohenEditor

Dredged Material Disposal in the Sea

3

T. Neville Burt and Caroline A. Fletcher

Dredged MaterialDisposal in the Sea

Abstract

Dredging is an economically essential activity to mostcountries, but it also has the potential to have a varietyof negative effects on marine flora and fauna. To regu-late these potential impacts, International Conventionshave been set up which realise the importance ofproperly managing the disposal of dredged material. In this paper the International Conventions are re-viewed, with special attention to the Draft 1996 Proto-col to the London Convention of 1972, which includesthe Dredged Material Assessment Framework (DMAF)and an explanation of the so-called “reverse list”. It alsoreviews the Oslo and Paris Convention (the OSPAR)recently revised in 1992. National and regional require-ments derived from these, as well as assessmentprocedures and monitoring programmes are alsodescribed.This paper was originally published in EnvironmentalAspects of Dredging, Proceedings of the CEDA-EuDASeminar held in conjunction with the PIANC Inter-national Conference on Inland and Maritime Navigationand Coastal Problems of East European Countries, atthe Technical University of Gdansk, Poland, September1996. It is reprinted here in a revised and updatedversion with permission.This subject is further elaborated in a recently publishedbook by Mr Burt and Ms Fletcher, Guide 2: Conven-tions, Codes and Conditions, Marine Disposal and LandDisposal, reviewed on pages 14-15 of this issue.

Introduction

Dredging is an economically essential activity to mostcountries and offers a solution to the problems ofsiltation of channels and trends of increasing ship sizes.However, dredging activities have the potential to havea variety of negative effects on marine flora and fauna,from disturbance of habitats for benthic communities inthe dredged area, to physical smothering or chemicalcontamination of those on the disposal site. Inappro-priate selection of disposal sites can also result inimpacts on fishery activities, recreation and navigation.In recognition of these potential impacts, International

Conventions have been set up which realise the impor-tance of properly managing dredged material. Issuesaddressed include limiting dredging to what is strictlynecessary, encouraging beneficial use and controllingthe disposal of dredged material. These issues areapproached differently and to varying levels by individu-al countries through their own policies and legislativesystem. However, for several countries, certain Inter-national Conventions and regional treaties are involvedin dredging activities and are incorporated within indivi-dual member countries legislation. Despite this, largedifferences do exist due to differences in historicalevolution of legislation, philosophy and attitudes to thebest management approaches.

T. Neville Burt is Principal Engineerin the Ports and Estuaries Group atHR Wallingford, England, specialisingin dredging matters. He is also Chairof the Central Dredging Association’sEnvironmental Steering Committee inwhich capacity he co-chaired theGdansk Conference, and co-presen-ted this paper on EnvironmentalAspects of Dredging at the confer-ence.

Caroline A. Fletcher received aBSc(Hons) in Chemistry fromBirmingham University (UK), anMSc DIC in Environmental Tech-nology, and a Doctorate in Environ-mental Engineering from ImperialCollege, London University (UK).She has been working at HR Walling-ford, England since 1995 where she ispresently an environmental pollutionscientist specialising in dredging andcontaminated sediments.

T. Neville Burt

Caroline A. Fletcher

INTERNATIONAL CONVENTIONS

In the 1970s protocols for the control of disposal ofmaterial to sea were set up, two of which include theLondon Dumping Convention and the Oslo Convention.They were set up primarily to regulate the disposal ofnoxious substances into the oceans, but they includedthe regulation of the disposal of dredged sediment aswell. This inclusion was in a way expected, given thatthe annual volume of dredged material disposed at seais by far the largest compared to any other materialending up at licensed disposal sites.

Although only a very small proportion of the dredgedmaterial that is disposed at sea is contaminated, dredg-ed material is generally regarded as waste, and a num-ber of national and international regulations and conven-tions have been drawn based on this perception. Thispaper reviews the main and more recent requirementsof the London Convention and the recently revisedOslo and Paris Convention, named the OSPAR Conven-tion.

At the heart of both these conventions are two basicprinciples:1. The precautionary principle, by virtue of which pre-

ventative measures are to be taken when there arereasonable grounds for concern that substances orenergy introduced into the marine environment maybring about hazard, harm, damage or interference,even when there is no conclusive evidence of acasual relationship between inputs and the effects.

2. The polluter pays principle, by virtue of which thecosts of pollution prevention, control and reductionmeasures are to be borne by the polluter.

A logical development of the first principle is the “re-verse list”, whereby only substances which have beenproved not to cause harm are permitted to be disposedat sea.

London Convention 1972In 1993 the London Dumping Convention was re-named the London Convention 1972 (LC 72) because itdid not want to be regarded as a “club” for people whodid dumping (Figure 1).

The LC 72 ArticlesThe LC 72 has ten main Articles which by and largeaddress the obligations of the Contracting Parties toensure that the properties of the material to be dis-posed of at sea are in accordance with the Conventionsrequirements, that the Parties encourage cooperationbetween them and seek the formation of RegionalAgreements, and that measures are taken to preventand punish any conduct in contravention of the Con-vention. Other articles are concerned mainly with thedetails of procedures for setting up and operating theConvention.

Revisions of the LC 72 have been undertaken and anew 1996 protocol to the London Convention 1972 hasrecently been adopted by the Special Meeting of Con-tracting Parties to the London Convention on the7 November 1996. The new protocol will replace theprevious Annex system and introduce the “reverselist” approach whereby substances which are permit-ted to be disposed of at sea are listed. This protocol isnot expected to be fully implemented for some 3 to 5years but will be put up for ratification in April 1997.Twenty-six countries have to ratify it of which 12 haveto be contracting countries. Amendments which havebeen undertaken include the promotion of ”sustainableuse” in line with the Rio declaration on Environmentand Development and Agenda 21. Another amend-ment of importance is the inclusion of the sea bed inthe definition of the marine environment. The effectwill be to bring most dredging activities (i.e. not justdisposal) under the control of the Convention.

There are two principal aims of this revision process.The first is to strengthen the control over disposal atsea, the second is to make the acceptance of theConvention more global.

Dredged Material Assessment Framework (DMAF)The Convention has adopted a new method of assess-ment of the suitability of material for disposal. This isknown as the Waste Assessment Framework (WAF).The implementation is not clear yet and it is still up toindividual countries to adopt it within their legislativeand regulatory systems. The dredged material guide-lines (DMAF) have been formed in such a way as tocomplement the Waste Assessment Framework(WAF). DMAF offers generic guidelines for decision


4

Figure 1. The International Maritime Organization building inLondon, UK, an agency of the United Nations, where the“London Convention 1972” was conceived. In November1996 a Draft Protocol to the LC 72 was issued for ratificationby member nations.

• General considerations and conditions• Disposal management techniques

Similarities and Differences with LC 72The OSPARCOM Guidelines and the LC Guidelines arevery similar in both structure and content. An importantdifference between them is that OSPAR offers flexibil-ity in the case where concentrations of contaminantsexceed “trace” levels. If under OSPAR it is shown thatmarine disposal is the “option of least detriment to theenvironment” this form of disposal may be permitted,whereas under LC Guidelines the marine disposal ofmaterials with “black list” contaminants exceeding“trace” levels is prohibited. Another differencebetween LC and OSPARCOM is that oil and its prod-ucts are listed in LC’s existing Annex 1 but are notincluded in the OSPARCOM. As the reverse list isimplemented fully these distinctions between theAnnexes will disappear and it will be necessary todemonstrate acceptable impacts for the disposalmaterial.

Other Conventions and Regional TreatiesThere are a number of other international conventionsand regional treaties set up with the general aim ofprotecting the aquatic environment (Figures 3 and 4)and a list is given in an Appendix.

ASSESSMENT OF MATERIAL

Philosophies and General ApproachesInternational Conventions and regional statutory re-quirements, such as EC Directives, have been incorpo-rated within individual member countries legislation andin order to meet these commitments, different regula-tory systems have been set up by each country. How-ever, large differences in approaches and interpretationoccur. The management and control of dredged mate-rial is addressed differently and to varying levels byindividual countries through their own policies andlegislative system. This is due to differences in histori-cal evolution of legislation, philosophy and attitudes tothe best management approaches. Three generalapproaches which exist are discussed below, however,they are not always applied in isolation and the legis-lation of an individual country may involve a hybrid ofthese approaches.

Standards ApproachA system of standards defining the quality of the dredg-ed material in terms of contaminants present (as eitherconcentrations or total loads) is used in some countries.This system prohibits sea disposal of dredged materialif selected contaminants are present at concentrationsabove a specified value. Sediment standards haveevolved by a number of philosophies and methods.Different approaches include knowledge of backgroundcontaminant concentrations in the area, assessment of

makers. A schematic outline of DMAF is given inFigure 2 and it is discussed in detail throughout thispaper.

Disposal of material for which contamination is not aconcern will still be subject to an audit such that seadisposal will be permitted subject to consideration ofbeneficial use options and assessment of disposal siteimpacts.

OSPARCOMThe revision of the Oslo and Paris Conventions wascompleted in 1992 and they are now known as OSPARConvention. The two original Conventions were the“Oslo Convention for the Prevention of Marine Pollu-tion by Dumping from Ships and Aircraft, 1972” andthe “Paris Convention of the Prevention of MarinePollution from Land-based Sources, 1974”.

The new OSPAR Convention has four Annexes:Annex 1 on the prevention and elimination of pollution

from land-based sourcesAnnex 2 on the prevention and elimination of pollution

from dumping or incinerationAnnex 3 on the prevention and elimination of pollution

from offshore sourcesAnnex 4 on the assessment of the quality of the

marine environment

The disposal at sea Annex 2 is set out in the form of areverse list of materials that may be disposed of at sea,with the dredged material being at the top of the list.

OSPARCOM Dredged Material GuidelinesAs with the LC 72, there are dredged material guide-lines. In 1989 the Oslo Commission decided to reviewthe 1986 Guidelines. France organised a seminar inNantes in November 1989 on the environmentalaspects of dredging and examined ways of reducingthe impact. A number of management tools wereidentified for incorporation in the revised dredgedmaterial guidelines.

These revised guidelines are presented in two parts.Part A deals with the assessment and management ofdredged material disposal, while Part B provides gui-dance on the design and conduct of monitoring ofmarine and estuary disposal sites.

The main constituents of Part A of the OSPARCOMrevised guidelines are:• Conditions under which permits for disposal of

dredged material may be issued• Assessment of the characteristics and composition

of dredged material• Guidelines on dredged material sampling and

analysis• Characteristics of disposal site and method of

disposal


5


6

Need for dredging

Dredged Material Characterisation

Is the materialacceptable ?

Can material be made

acceptable ?

Beneficial usepossible

Beneficial use

Identify and Characterisedisposal site

Determine potential impactsand prepare impacthypothesis(eses)

Issue permit ?

Implement project andmonitor compliance

Field monitoring andassessment

DREDGED MATERIAL ASSESSMENT FRAMEWORK

Representation of the jurisdictional boundary of the convention

Yes

Yes

Source Control

NoNo

No

No

YesYes

Alternativedisposal

Figure 2. The London Convention Dredged Material Assessment Framework (DMAF).

the field conditions in the laboratory and the separationof the effects of contaminants from other stresses,such as pore water sulphide content. In addition, thismethod is costly to use as a regulatory tool. Also, thesetests give a determination of the effects at a specieslevel and at best are only indicative at an ecosystemlevel.

Case-specific ApproachThis approach assesses each case individually and isusually regarded as a pragmatic approach. The suitabili-ty of the dredged material for disposal may be as-sessed on its quantity and quality and on characteristicsof the disposal site. Bioassays may also be employed ifnecessary, but essentially the philosophy is to assessthe dredged material disposal based on specific charac-teristics of the dredged material and the receiving site.

Assessments on a case-by-case basis has the advan-tage of giving flexibility to adopt the best environmentaloption for that area. However, the lack of uniformguidelines makes it difficult for dredging operators tomake informed decisions and frequently a lengthyconsultation process is required with involved authori-ties.

Reducing the Amount of MaintenanceThe new LC 72 DMAF asks the question “Is it neces-sary to dredge?” (Figure 2). The immediate answer isusually “yes” but the matter is worthy of furtherconsideration on both economic and environmentalgrounds. There are several options.

One of the more radical ones was adopted by the Portof Rotterdam in simply re-defining ”the bed” in termsof a density measurement. This acknowledges theexistence of fluid mud through which vessels cansafely navigate and eliminates the need to removesuch material.

Another example is the dredging carried out by theTees and Hartlepool Port Authority Ltd. A review wascarried out in 1990 which showed:i) allowing overspill of the hopper was creating a

mechanism whereby dredged material was beingcarried further upriver by stratified flow, requiring itto be redredged later;

ii) the estuary was being gradually deepened by dredg-ing more than was necessary for safe navigation.

Engineering solutions have also been found in a numberof situations for example the deflector wall at Hamburgwhich controls the formation of an eddy in a tidal basin.A United Kingdom example is the recent construction ofgroynes on the Diver’s Shoal in the Thames Estuary.These were designed to concentrate the flow into thenavigation channel and therefore enhance self scouring.The scheme was tested in a physical model and ap-pears to be working well in nature.

benthic community structures for various contaminantlevels and a “standards” biological effects-basedassessment.

The strength of this approach is that it relies only onmeasurements that can be made in most analyticallaboratories and contaminant concentrations or loadscan be easily compared to the guidelines. The stan-dards approach, therefore, offers a clear managementtool and a basis for licensing.

The weaknesses of this approach is that it is inflexibleand may therefore impose unreasonably harsh restric-tions in some cases or be too permissive in a sensitiveenvironment.

Ecotoxicological ApproachThis approach addresses the impact of contaminatedsediments on ecology more directly. There are varioustechniques which adopt this philosophy and are out-lined below.

Generally the strengths and weaknesses are commonfor these techniques. A strength is that such a systemis related to the sediments specifically and thereforeaddresses their physico-chemical properties on a moresite specific basis. Weaknesses lie in the uncertainty ofmeasuring and predicting ecotoxicological impacts andthe lack of scientific knowledge and appropriate tech-nologies. However, scientific knowledge is advancingand methods for predicting ecotoxic effects are im-proving.

Elutriate testThis assesses toxicity by measuring the releasablecontaminants from dredged material and thereforeindicate the potential contamination of adjacent surfaceand groundwaters. Elutriate tests give an indicationonly of the bioavailable fraction.

Bioassay approachThis approach observes the responses of selected testspecies to specific contaminants under laboratoryconditions.

Implementation of this method at a specific site re-quires collection of data on in-situ sediment chemistry,on the chemistry of contaminant-spiked sediments,and on the responses of test organisms. In addition,data is generated through laboratory experiments andsufficient field validation (which addresses contaminantinteraction and the effects of physical sediment varia-bles on the responses of benthic organisms) are re-quired. Therefore this approach to date mainly involvessingle contaminants or relatively simple mixtures ofcontaminants on various sediment types.A strength of this method is its suitability for all classesof chemicals and most types of sediments.A weakness of this method is the inability to reproduce


7

Assessment of the Dredged Material PropertiesAdequate characterisation of the dredged material is aprerequisite to proper assessment of the environmen-tal impacts of disposal. The quantity, physical proper-ties, chemical properties and biological impacts needappropriate assessment. As discussed earlier in thispaper, a number of countries have developed their ownassessment procedures and approaches. In a largenumber of cases, standards to compare sedimentproperties with have also been developed. Some ofthese standards, it can be argued, are country-specific,where as others could be adopted by neighbouringcountries. This paper, however, will review the basis ofthe assessment of the dredged material properties, aswell as the procedure of the London ConventionDredged Material Assessment Framework (DMAF) asshown schematically in Figure 2. Under these guide-lines assessments of the quantity and physical charac-teristics are required while exemptions for the chemicaland biological assessments exist if the material is froman area known to have no contaminant sources.Emphasis is placed on a requirement for sufficientinformation on contamination and the physico-chemicalconditions while biological investigations required willdepend on the potential impacts.

London Convention Dredged Material AssessmentFrameworkDMAF has been adopted in the text of the Draft 1996Protocol to the London Convention 1972 and offers

generic guidelines for decision makers. It is up to indi-vidual countries to adopt within their legislative andregulatory systems. The new protocol will replace theAnnexes and introduce the “reverse list” approachwhereby substances which are permitted to be dis-posed of at sea are listed. This protocol is not expectedto be fully implemented for some 3 to 5 years but willbe put up for ratification until April 1997. To be imple-mented, 26 countries have to ratify it, of which 12 haveto be contracting countries.

The LC Guidelines for contamination levels in dredgedmaterial follow a qualitative approach whereby thecontaminants are categorised in two Annexes:Annex I lists contaminants which are known to causeharm to aquatic organisms even in low concentrations.These contaminants are organohalogens, mercury,cadmium oil an oil products, radioactive substances,materials for biological warfare and persistent plastics.Annex II lists the contaminants which should not bepresent in concentrations higher than 1,000ppm (i.e.0.1%), with the exception of lead which should not befound in concentrations higher than 500ppm (i.e.0.05%). Annex II listed contaminants are Arsenic, Lead,Copper, Zinc, Organosilicons, Cyanides, Fluorides andPesticides. Under the London Convention, if any of theAnnex I or II substances are found in significant con-centrations, a special permit would be required in orderto dispose of the dredged sediment. A general permitfor offshore disposal, under the LC, is howeverrequired in order to establish whether or not the dis-posal at sea of the dredged material containing Annex Iand II substances might cause undesirable effects.Such effects are considered to be either chronic oracute, and toxic for marine or human life. This presentsystem is however going to change in the future as thenew reverse listing approach has been adopted. It ishowever not ratified yet.

Under the new protocol, the Annex I now outlines thereverse list principle and lists wastes and other matterwhich may be considered for dumping being mindful ofthe objectives and general obligations of this protocolset out in articles 2 and 3. Dredged material is includedon this list.Annex 2 outlines WAF where waste minimisation byprevention at source, assessing other disposal options,characterisation, action lists, dump site selection,assessment of potential effects, monitoring and per-mits procedures are outlined.

Quantitative assessment of dredged material propertiesAs mentioned previously, a number of countries aroundthe world, active in the dredging and disposal scenehave developed their own quantitative assessmentprocedures for dredged material properties. With theexception of the USA approach to the assessment ofthe properties, which is both chemical and ecotoxico-logical, the rest of the quantitative assessments are


8

Figure 3. Open sewers discharging into this Asian harbourpollute the sediment which then needs to be dredged anddisposed of.

The considerations mentioned above are simply anextract from a much longer list. This paper only aims toreview but a few. But let not such review give thenegative impression that beneficial uses of dredgedmaterial cannot be reasonably achieved. On the contra-ry, experience on both sides of the Atlantic Ocean hasshown that good planning, good communicationsbetween project team and funders, understanding of allfactors involved, (particularly of their interactions), andgood understanding of the timescale involved, can turna traditionally thought of waste into a useful resource.

Requirement to explore beneficial usesAs part of the assessment it is now required that con-sideration be given to other possible disposal routesincluding the use of material beneficially. Such uses aremostly at their development stage at the moment.Questions that DMAF raises are “is the materialacceptable?” and “can the material be made accept-able by some sort of treatment?”. Generally there ismore success in finding uses for granular material,sands and gravels than fine silts which form the major-ity of maintenance dredgings in many countries. The development of beneficial use options for suchmaterial is required (Figures 5 and 6).

ASSESSMENT OF SEA DISPOSAL SITES

AssessmentExisting Conventions require that, if sea disposal isproposed, appropriate assessment of the dredgedmaterial and the proposed disposal site needs to beundertaken so that any likely impacts of the disposaloperation can be identified. The guidelines developedby the London Convention and OSPARCOM provide

based on the chemical composition of the dredgedsediment. The chemical parameters mainly consideredare the majority of the heavy metals known for theirtoxicity to life, and a wide range of organic contami-nants such as hydrocarbons, polychlorinated biphenylsand pesticides. These parameters were chosen be-cause of their ability to cause either chronic or acuteharm to living organisms.

Some of the chemically-based quantitative assessmentof dredged material properties also considers theconcentrations of organic matter and fine sediment (i.e.silt) particularly the concentration of particles sizesbelow 63µm. The reasoning behind this considerationis the affinity that certain contaminants have for either,or both organic matter and fine sediments.

Some countries’ sediment quality numerical standardsare much stricter than others. Although a number ofcountries around the world base their sediment qualityassessment on the numerical standards, there isincreasing recognition that a case-specific approach ismore effective as it tends to concentrate on localparameters influencing sediment quality.

Potential contamination release from dredged materialA wide range of physico-chemical reactions take placefrom the moment a waterway sediment is being dredg-ed until it is finally deposited at its disposal site. Thesereactions may lead to the release of substances whichhave the potential to harm life and interfere withhuman welfare. Such substances are particularly foundin soft sediments because of their affinity to adhere tofine particles (smaller than 63µm). The options forbeneficial use of such soft sediment may therefore berestricted.


9

Figure 4. Estuaries are still too often used as dumping grounds for all types of waste.

the user with a tool for predicting the consequences ofthe disposal and for validating those predictions againstobservations. This objective approach means that theimpact of disposal of dredged material upon the marineenvironment can be meaningfully addressed, with themain aims, as previously mentioned, being;• to protect the marine environment• to prevent interference with amenities or other

legitimate uses of the sea

Studies and tests to be carried out during the assess-ment generally include;• the general requirement of the LC 72 and OSPAR-

COM• chemical and physical analysis• biological testing• formulation of an impact statement• the development and use of quality standards• monitoring

In addition, the OSPARCOM guidelines suggest thatinformation on density, % solids, grain size fractionsand total organic carbon should be obtained in additionto mandatory analysis of substances listed in Annex 1and Annex 2 of the Convention. A technical annex tothe Oslo Convention sets out primary and secondarydeterminants.

It has been demonstrated by Gurbatt and Campbell(1989) that modelling has a role in the assessmentprocess, where the effects models fall into two cate-gories; those concerned with immediate effects at andnear the disposal site (near-field) and those with longer-term consequences of contaminant dispersion (far-

field). The disposal site evaluation should involveassessments of the sea bed, the water column andproximity of the operation to areas of interest.

Contamination of the dredged material has the poten-tial to impact on biota with valuable fish and shellfishstock being of importance. However, it is also impor-tant to appreciate that sea disposal of uncontaminateddredged material can also cause major environmentalimpacts through, for example, smothering the sea bedand suspended sediments reducing essential lightpenetration. The significance of the impacts willdepend on whether the site is a retentive or dispersivesite.

The physical effects are an unavoidable result of mostdisposal operations. Questions which need to beaddressed are outlined in DMAF. Therefore, monitoringand field assessments are typically required and arediscussed later in this paper.

Impact HypothesisThe London Conventions DMAF states that impactassessments should lead to a concise statement of theexpected consequences of the disposal operation. Thisis being termed the “impact hypothesis”. This compri-ses a summary of the potential effects on humanhealth, living resources, amenities and other legitimateuses of the sea. It should define the nature, scale andduration of expected impacts based on reasonablypessimistic (i.e conservative) assumptions.

Approaches and content of these impact assessmentswill vary depending on whether the site is a retentive


10

Figure 5. Example of contaminated sediments being processed in Hamburg, Germany.

21. Availability of alternative land disposal or treatment22. Consideration of possible beneficial uses

Contaminated Dredged Material The Conventions aim to limit sea disposal of contami-nated dredged material with a view to minimisingadverse environmental effects in the marine environ-ment. Alternative disposal options such as open waterdisposal followed by capping, upland confined disposaland controlled beneficial use will then need to beevaluated on a case-by-case approach. A framework forsuch an assessment has been developed by PIANC(PIANC PTC 1-17, 1996). If none of the disposal optionsmentioned are feasible and the dredged material isheavily contaminated, it is always possible to considertreatment provided that treatment costs can be met.Good preliminary research is essential for any treat-ment project. The licensing/permit authority has to beable to predict any impact contaminated dredgedmaterial may have of the proposed disposal on thereceiving environment and man.

Ultimately, the problems of contaminated dredgedmaterial disposal can be controlled effectively only bycontrol of point source discharges to waters fromwhich dredged material is taken.

Enforcement and ComplianceUnder LC72 each party shall take in its territory appro-priate measures to prevent and punish conduct incontravention of the provisions of the Convention. They are also obliged to apply the Convention to ves-sels registered in its territory or flying its flag. It alsoapplies to vessels loading in their ports any material

site or a dispersive site. These differences are outlinedin DMAF Section 6.3 and 6.4.

Licensing and PermitsIn most countries the responsibility for licensing/ grant-ing of permits and enforcement is undertaken by aGovernment Department, usually a Ministry or Depart-ment of the Environment or similar body. Sometimes itis delegated from such bodies to an EnvironmentalProtection agency or similar body. While some govern-ments put the responsibility to Transport, Marine orFisheries Departments.

Anyone wishing to dispose of dredged material shouldapply for a licence in advance. A licence applicationshould generally contain the following informationalthough as previously mentioned in some cases (eg“clean” sand) some testing of chemical and biologicalparameters can be omitted. The licence application liststhe requirements of the assessment process and isgiven below;

A. Concerning the material1. Source, total amount and average composition

(e.g. per year)2. Form (solid, sludge, liquid, gaseous)3. Properties; physical (e.g. solubility and density),

chemical and biochemical (e.g. oxygen demand,nutrients) and biological (e.g. presence of viruses,bacteria, yeasts and parasites)

4. Toxicity5. Persistence: physical, chemical and biological6. Accumulation and biotransformation in biological

materials or sediments7. Susceptibility to physical, chemical and biochemical

changes and interaction in the aquatic environmentwith other dissolved organic and inorganicmaterials

8. Probability of production of taints or other changesreducing marketability of resources (fish, shellfish,etc)

B. Concerning the method of disposal9. Details of the dredgers or barges to be used10. Details of the proposed method of placement11. Rate of disposal12. Proposed monitoring system

C. Characteristics of the disposal site13. Location14. Dilution and dispersion characteristics15. Water characteristics16. Sea bed characteristics17. Existence of other dump sites in the area

D. General considerations18. Possible effects on amenities19. Possible effects on marine life20. Other uses of the sea


11

Figure 6. Processed sediment being used in landscapingproject, Hamburg, Germany.

which requires disposal. This gives the state the rightto enforce the Convention on ships (i.e dredgers) onnon-contracting parties.

The Convention gives the right to stop, board andinspect any vessel suspected of illegal dumping. AnyContracting party may adopt additional measures inaccordance with the principles of international law toprevent disposal at sea.

The question of penalties is a matter for each state todecide. The guiding principle is that it should relate tothe damage caused, however, this is difficult to evalu-ate since much of the damage is likely to be ecological.The only indication of enforcement and compliance bycontracting parties to the Conventions are the licencesor permits issued for disposal operations. For example,the Secretariat of the London Convention receivesreports from contracting parties notifying annually thepermits issued in the previous year, or reports statingthat no permits have been issued in that year, the socalled ”nil reports”. However, many contracting coun-tries do submit reports or contact the secretariat. Ofthe 71 contracting parties registered in 1992, 11 have

reported irregularly in recent years, while 25 can beregarded as “consistent non reporters”. Reasonssuggested for this is that some countries are landlocked while others have only recently signed up.

FIELD MONITORING AND ASSESSMENT

Any monitoring programme assessing a disposaloption, particularly when contaminated dredged mate-rial is involved, should be regarded as essential. Thewhole essence of monitoring is to control the imple-mentation of the proposed disposal and prevent envi-ronmental quality implications. When an impact hypo-thesis has been made it will form the basis of amonitoring programme.

There are two main components to a monitoring pro-gramme; surveillance and scientific investigation.Surveillance involves an assessment of the spatial andtemporal changes in the distribution, fates and effectsof contaminants introduced by specific dumping opera-tions. It aids in demonstrating the acceptability andcompliance of the overall intent of the Convention.


12

Global1 United Nations Convention on the Law of the

Sea, 1982.2 International Convention for the Prevention of

Pollution from Ships, 1973, as modified by theProtocol of 1978 relating thereto (MARPOL73/78).

3 Convention on the Prevention of Marine Pollutionby Dumping of Wastes and Other Matter, 1972(London Dumping Convention).

4 Basel Convention on the Control of Transbounda-ry Movements of Hazardous Wastes and theirDisposal, 1989 (Basel Convention).

Regional5 Convention for the Prevention of Marine Pollution

by Dumping from Ships and Aircraft, 1972 (OsloConvention).

6 Convention on the Protection of the MarineEnvironment of the Baltic Sea Area, 1974 (Helsin-ki Convention).

7 Convention on the Prevention of Marine Pollutionfrom Land-based Sources, 1974 (Paris Conven-tion) – 1988 Amendment.

8 Convention for the Protection of the Mediterrane-an Sea against Pollution, 1976 (Barcelona Conven-tion) – 3 protocols.

9 Convention for the Protection of the NaturalResources and Environment of the South Pacific

Region, Noumea, 1986 (SPREP Convention)–2 protocols.

10 Kuwait Regional Convention for Co-operation onthe Protection of the Marine Environment fromPollution, 1978 (Kuwait Convention) – 2 protocols.

11 Convention for the Protection of the MarineEnvironment and Coastal Area of the South-EastPacific, 1988 (Lima Convention) – 4 protocols.

12 Convention for Co-operation in the Protection andDevelopment of the Marine and Coastal Environ-ment of the West and Central African Region,1981 (Abidjan Convention) – 1 protocol.

13 Convention for the Protection, Management andDevelopment of the Marine and Coastal Environ-ment of the Eastern African Region, 1985 (NairobiConvention) - 1 protocol.

14 Convention for the Protection and Developmentof the Marine Environment of the Wider Caribbe-an Region, 1983 (Cartagena Convention) - 1protocol.

15 Regional Convention for the Conservation of theRed Sea and Gulf of Aden Environment, 1982(Jeddah Convention) - 1 protocol.

16 Guidelines for the Protection of the MarineEnvironment Against Pollution from Land-basedSources (Montreal Guidelines, 1985).

17 Convention for the Protection of the Environmentbetween Denmark, Finland, Norway and Sweden(Stockholm Convention, 1974).

APPENDIX. LIST OF INTERNATIONAL AGREEMENTS, PROTOCOLS AND GUIDELINES

activity, it encourages the co-operation of the sub-contractors, particularly when the project managerrequires regular feedback on working programmes anddetailed cost estimates.

Although monitoring programmes are project-specific,the experience obtained from each plan can form avery good starting point for other projects.

In addition, the information gained needs to be used tomodify or terminate the field monitoring, modify orrevoke the permit licence or refine the basis of theassessment process.

Conclusions

Recognising that:1. Both capital and maintenance dredging are neces-

sary operations.2. They are costly operations.3. In general they do not create wealth, especially

maintenance dredging.4. Contamination of the dredged material is rarely the

fault of the person wishing to dredge.5. Uncontaminated dredged material is a resource,

not a waste.6. Taking good care of our environment (both marine

and on land) is important both for our own well-being and that of future generations.

Leads to the aims that:1. Dredging should be carried out with least detriment

to the environment.2. Dredging should be carried out at minimum cost

compatible with achieving (1).3. Pollution should be controlled at source.4. Wherever possible beneficial use should be made

of the dredged material.

References

Gurbatt, P.A. and Campbell, J. “Evaluation of dumping sites”. Seminar in Nantes, France.

1989.

Permanent International Association of Navigation Congresses(PIANC) PTC 1-17.“Handling and Treatment of Contaminated Dredged Material

from Ports and Inland Waterways ‘CDM’”, Volume 1. Report

of the Working Group No.17 of the Permanent Technical

Committee I. 1996.

Scientific investigation is aimed at improving under-standing of the fates and effects of contaminantsreleased into the marine environment.

Setting up a Monitoring PlanMonitoring plans should have clear, attainable andmeaningful objectives, with a built-in element offlexibility. A logical and realistic sequence of stagesshould form the basis for designing a monitoring plan.There are five steps for developing a physical/biologicalmonitoring programme for open water disposal ofdredged material, which can also be adopted in thecase of contaminated dredged material disposal. These steps are:1. Designating site-specific monitoring objectives2. Identifying components of the monitoring plan3. Predicting responses and developing testable

hypothesis4. Designating sampling design and methods, which

include selection of equipment and techniques5. Designating management options

An assessment of the disposal operation should atleast comprise a baseline monitoring plan, alongside asite survey plan, and a post-disposal monitoring plan.

Baseline MonitoringBaseline monitoring is undertaken before the projectbegins and forms the basis for the assessment of thedisposal. The purpose of a baseline monitoring, coupledwith a site survey, is to determine the amount of mate-rial to be dredged, the extent of the contamination andset a reference for post-project monitoring.Baseline monitoring should be done sufficiently inadvance of the first project stage so that conditions andadditional data requirements can be assessed beforeoperational decisions are made.

Post-disposal MonitoringPost-disposal monitoring should be consistent with thebaseline monitoring. That is, the monitoring locations,and the types and quantities of samples must be thesame before and after the disposal. Post-disposalmonitoring plans should however have some flexibilityto allow for a certain degree of modification after theoperation so that special needs created by failures oroperational difficulties can be accommodated (PIANCPTC 1-17, 1996).

Long-term monitoring is advisable when contaminateddredged material is disposed of. At the disposal site theamount of monitoring required after disposal willdepend on the size and location of the disposal site andthe degree of contamination at the site.

Feedback InformationThe conscious execution of a monitoring plan shouldhelp determine more realistic preliminary project costsin future projects. Since monitoring is not a stand-alone


13

Environmental Aspects of DredgingGuide 2: Conventions, Codes and Conditions; Marine Disposal and Land Disposal

As stated in the Preface to Guide 2, “At a time whenthe environmental impact of dredging in all its aspectsis coming under scrutiny, it is essential that those whoare involved in its practice are aware of the legislationwhich is evolving and its underlying philosophies”.

For this reason, the International Association of Dredg-ing Companies (IADC) and the Central Dredging Associ-ation (CEDA) decided that a guide to international andnational legislation was a suitable subject to be includ-ed in their series of publications on ”the environmentalaspects of dredging”.

Seeking to supply such an overview to the dredgingindustry, this two-part guide presents a summary of theextensive international framework of legislation relatingto dredging and the disposal of dredged material.Furthermore, it describes how these internationalagreements are then implemented and regulated bygovernmental agencies at the national level. Because scientific knowledge is increasing and imple-mentational frameworks are evolving, the legislation isconstantly being changed, and recommendations aremade about how to comply with these changes.

Conventions, Codes and Conditions was written byT. Neville Burt and Caroline Fletcher, both of HR Wallingford, United Kingdom. The Editorial Board,comprising members of IADC and CEDA, was activelyinvolved in the development of the concept. Board members are R. Nick Bray, Director, DredgingResearch Ltd., United Kingdom, Anna Csiti, Manager,CEDA, Delft, The Netherlands; Peter J.A. Hamburger,Secretary General, IADC, The Hague, The Netherlands;and Gerard H. van Raalte, Assistant Manager, Hydrona-mic BV, Papendrecht, The Netherlands.

This newly published guide offers all promoters ofdredging works an up-to-date report on current legalrequirements. Because the subject matter is so vast,the authors decided to split Guide 2 into two volumes,one covering Marine Disposal, the other Land Disposal.

Guide 2a: Marine DisposalIn the recent past, the environmental lobby wasarguing strongly for a “precautionary approach” whichdictates that unless it can be demonstrated that

impacts are acceptable then disposal should not beallowed. This approach is embodied in the LondonConvention and several others. It pre-dated and stimu-lated much of the research which has been under-taken, particularly in the USA, where some dredgingoperations were stopped until the impacts could beproperly assessed.

A major problem with all of the national and internation-al legislation is standardising the basis of assessment.The means of assessment can range from simple tovery complicated. Obviously, not all countries (includingsome who have signed the London Convention) havethe resources to carry out complicated and expensivetesting procedures, though as the book points out, thisshould not be used by responsible people as an excusefor disposal of environmentally harmful material.

Guide 2a presents three basic approaches to considerwhen establishing guidelines and the management ofdredged material disposal:i) standards; whereby permitted concentrations or

total loads of contaminants are stated;ii) ecotoxicological; whereby the toxic effects of the

material are tested in a laboratory;iii) case-by-case; whereby each case is assessed in the

context of the receiving environment; it may involveboth other approaches.

Guide 2a is presented in nine chapters. In Chapter 1,the international conventions are outlined which strong-ly influence signatory countries’ policies. Chapters 2 to8 review the legislation, standards or best practice forindividual countries. The countries are groupedgeographically and in alphabetical order.

The discussion on each country has been divided intofive sections: a brief background, the statutes andregulations governing dredged material disposal, theimplementation bodies, the procedure undertaken,permits and, standards, and finally the future directionthat legislation is heading in each country. Chapter 9concludes the findings and assesses future trends.

Several appendices are attached, including one inwhich the Dredged Material Assessment Framework(DMAF) is outlined.


14

Guide 2b is presented in six chapters. In Chapter 1 anoverview of land disposal options is presented and asummary of the differences and similarities of disposalpractices is provided. In Chapters 2, 3, and 4 inter-national disposal practices are described. Generalconclusions arising from the review of internationalpractices are given in Chapter 5. Finally, in Chapter 6general recommendations are given for establishing adredged material management system in the future.

Both Guide 2a and 2b are enriched with extensivetables and illustrations.

Other Books in the SeriesThe IADC/CEDA series of publications “The Environ-mental Aspects of Dredging” is planned to be sevenvolumes, published over a two year period. It compri-ses a number of integrated, but stand-alone, guides ondredging and environmental issues. The first guide in the series entitled, Players, Processesand Perspectives, written by Mr. Jan W. Bouwman andMr. Hans P. Noppen of AVECO bv, The Netherlands,was published in September 1996. It presents a syste-matic approach to the decision-making process ofenvironmental dredging. It covers who is involved inthe decision to dredge, and how and why a decision isreached.Next in the series, Guide 3, scheduled for publication inthe Spring of 1997 will be a discussion of pre-dredginginvestigations including the identification and classifica-tion of sources of pollution guidelines for field sur-veying, sampling and laboratory testing.

All books in the series may be ordered from the IADCSecretariat in The Hague. Guide 2: Conventions,Codes and Conditions; Marine Disposal and LandDisposal (a, 44 pp.; b, 72 pp. Illustrated. NLG 40) isavailable now.

Guide 2b: Land DisposalGuide 2b reviews international land disposal practicesfor dredged material. Appropriate guidelines andstandards, where they exist, are summarised for anumber of countries, including the United Kingdom,The Netherlands, Canada and Germany. The differentapproaches by each country in devising their assess-ment systems are discussed and the strengths andweaknesses evaluated. In general it is difficult to discuss land disposal criteriaisolated from marine disposal guidelines because inmost countries the majority of dredged material isplaced at sea. However, this volume assumed that landdisposal options are applied either because transportcosts to sea are inhibitory, beneficial use is not anoption, or the material is too contaminated to be dis-posed of at sea. The last factor proved to be the mostrelevant.

The requirements to reduce contaminant inputs to thesea under international conventions, such as theLondon Convention, and the implementation of recentdirectives (EC Waste Directive) in the legislation ofindividual European countries, are causing a reassess-ment of the management of dredged material in mostcountries. Notably, changes in the perception andclassification of dredged material as a resource and notas a waste have occurred relatively recently.

Guide 2b clearly emphasises the need for a studywhich addresses the question of suitable standards forthe various land-based disposal options. It suggeststhat guidelines be established based on feasible landdisposal options. These guidelines would incorporatesuitable disposal standards which can be either qualita-tive, quantitative or both. The report recommends thatthis would be best achieved in a staged approachwhere an initial review of international practices willform a sound basis for developing suitable guidelines.

Environmental Aspects of Dredging

15

Maurice de Kok, Wouter Dirks and Rienk Hessels

The Øresund Fixed Link:Dredging Reclamation

Abstract

The Øresund Fix Link project will be a 16 km longbridge-tunnel link connecting Kastrup, Denmark withLernacken, Sweden. The project has been divided into three contracts:No. 1, the Tunnel Contract; No. 2, the Dredging andReclamation Contract; and No. 3, the Bridge Contract.

The dredging work encompasses the excavation of a3500 m long tunnel trench in which the tunnel sectionswill be placed. Then, using the dredged material, a4000 m long artificial island complex is being reclaimedto form the connection between the tunnel and thebridge. Work also includes the deepening of two canalsand shore protection.

The dredging and reclamation contract (No. 2) has beenawarded to the Øresund Marine Joint Venture (ØMJV)and this article describes some aspects of ContractNo. 2, Dredging and Reclamation.

The article is presented in three sections dealing withthe hydraulic dredging and reclamation activities: ageneral introduction defining the scope of the works,environment, design, tolerance and survey and plan-ning, written by Maurice de Kok; the soil conditions anddredgeability written by Wouter Dirks; and the wear ofpipelines, written by Rienk Hessels.

Introduction

The European Council has identified the Øresund FixedLink as one amongst 14 priority project in the TransEuropean Network programme. The fixed motorwayand railway link across the Øresund will connectKastrup on the Danish coast with Lernacken on theSwedish coast.

The link will consist of the following elements:– an artificial peninsula extending 430 m from the

Danish coast at Kastrup– an immersed tunnel 3510 m long under the Drogden

Navigation Channel


16

Maurice de Kok graduated in 1989from the Technical University Delft,The Netherlands with a MSc in CivilEngineering. He was employed byHoek Engineering bv and BallastNedam Engineering bv for work onthe West Bridge of the StoraebeltProject in Denmark. Since 1991 he hasbeen a Project Organiser, Productionand Planning Manager, and ProjectEngineer for Ballast Nedam.

Wouter Dirks was award his MScfrom the University of TechnologyDelft, The Netherlands in MiningEngineering. As an EngineeringGeologist, he has been working forBallast Nedam since 1990 and ispresently working at the ØresundFixed Link project.

Rienk Hessels received his MSc fromthe University of Technology Eind-hoven in Construction Engineeringand his MBA from Erasumus Univer-sity, Rotterdam, The Netherlands.Since 1988 he has worked for BallastNedam and is presently assigned tothe Øresund Fixed Link project.

Maurice de Kok

Wouter Dirks

Rienk Hessels

– construction of a motorway and railway at the island;and dredging of:

– work harbours and access channels at the peninsula and island 1,300,000 m3

– trench for installation of the tunnel 2,300,000 m3

– relocation and deepening of the Flinte Channel 1,300,000 m3

– compensation dredging to achievezero blocking of water flow. 1,800,000 m3

Figure 1 gives an overview of the site boundaries forthe dredging and reclamation contract and indicateshydraulic dredging upon completion later in 1977.

The artificial peninsula will serve to reunite the passen-ger track from the underground station at the airportterminal with the freight track running north of theairport. The motorway along the northern edge of thepeninsula joins the railway at the entrance to the Drog-den tunnel portal. Furthermore, the peninsula willaccommodate a track leading to a train maintenancework area.

The artificial island south of Saltholm will form thetransition between the tunnel and the westernapproach bridge, including a 750 m long level and

– an artificial island 4055 m long south of Saltholm– a western approach bridge 3014 m long between

the island and the high bridge– a cable-stayed high bridge 1092 m long across the

Flinte navigation channel– an eastern approach bridge 3739 m long from the

high bridge to the Swedish coast at Lernacken– a terminal area with toll station and Link Control

Center located on the Swedish coast at Lernacken.

Three contracts have been awarded to build the FixedLink: No 1. the Tunnel Contract; No 2. the Dredging andReclamation Contract; and No 3. the Bridge Contract.

The Contractor that won the dredging and reclamationcontract is the Øresund Marine Joint Venture (ØMJV)consisting of: Per Aarsleff from Denmark; Great LakesDredge & Dock Company from the USA; and BallastNedam Dredging from The Netherlands.

SCOPE OF THE WORKS

The dredging and reclamation contract comprises: – construction of bunds for the peninsula and island;

and

The Øresund Fixed Link: Dredging and Reclamation

17

Figure 1. An overview of the site boundaries for the dredging and reclamation contract.

straight section for railway crossovers. From the tunnelportal on the western end of the island the motorwayruns alongside the railway to the north until the easternend, where it is led over the tracks on a viaduct to enterthe upper level of the bridge. Figure 2 shows the pro-gress of the works at 12 July 1996.

ENVIRONMENT

Strict environmental requirements are in force gover-ning both the construction of the Link and the impact ofthe completed Link on the surrounding environment.A main requirement is that the Fixed Link must notblock the water flow in the Øresund. Through theexecution of compensation area dredging, the blockingeffect will be reduced to zero.A second requirement is that spillage from dredging inthe seabed and from the reclamation areas may notexceed 5 per cent on average.

The Contractor has developed a system to monitor orestimate at all times every spill source during dredgingoperations in the construction area. There will be trans-port of sediment in connection with dredging, transportand reclamation operations, partly as suspended sedi-ment transport, partly as bottom transport.

On the basis of daily surveys the daily spill and dredgedquantities are made up for the spill monitoring anddredging control authorities. The quantities are control-led and corrected weekly by means of surveys of theseabed, accurate production estimates and reevalu-ation of the discharge and turbidity measurements.

All dredged seabed material is reused in the reclaimedareas, which include sedimentation basins. This entailsthe following advantages with respect to environmen-tal impact:– minimal sediment spillage;– need for dumping sites; and– reduced need for import of sand and gravel from

borrow areas.

HYDRAULIC DREDGING AND RECLAMATION

To carry out the dredging works the Contractor hasdeployed large equipment; one of the world’s largestdipper dredgers Chicago, bucket capacity 21 m3 andcutter suction dredger (CSD) Castor, cutting power5000 hp and pumping power 10,000 hp.

From an early stage of the project, the ØMJV had todredge large quantities of hard material. The main jobof the hydraulic dredging work consists of dredging aquantity of approximately 2,400,000 m3 to a maximumdepth of 23 m in the Tunnel Trench. Figure 3 gives across-section of the Tunnel Trench with the varioustypes of soil to be dredged.The cutter suction dredger Castor has been substantial-ly modified to be fully prepared for the dredging worksin the Øresund. The main parts of the cutter suctiondredger are:– Cutter: the tool with which the soil, is being loos-

ened. The cutting power on the Castor was upgra-ded in The Netherlands during 1996 from 1,700 kWto 3,600 kW in order to be able to cut through thehard material the Contractor expects in the TunnelTrench. The cutter is supported by the ladder andthe ladder provides breaking power through itsweight of 650 tons combined with the pulling forcesto both anchors.

– Pumping system: which causes vertical and horizon-tal transportation to the required deposition area. The total installed pumping power of the dredge is10,000 hp and it is possible to increase this capacityby adding up to two booster stations, called Malmöand Kopenhagen of 5000 hp each to increase pump-ing capacity.

– Control room at the bridge: the nerve centre fromwhere the whole dredging operation is monitoredand controlled.

– Spud carrier: the spud fixes the position of thedredger to the ground.

– Gravity anchors to create holding force for the sidewires that makes the dredger swing from portside to


18

Figure 2. Progress of the works at 12 July 1996 (photo: Jan Kofod Winther).

The height of the DGPS antenna above the ship’sreference point is exactly known, together with theship’s heave, roll, pitch, trim, list and draught measure-ments the actual tide level with reference to DKS willbe calculated. The survey data is post-processed toremove any erroneous fixes or depths, and then com-

starboard and vice versa. Figure 4 shows the cutterdredger Castor and gravity anchors in the Øresund.

DESIGN, TOLERANCE AND SURVEY

Strict tolerances on the design apply in the TunnelTrench as shown in Figure 5. The Contractor has instal-led a Real Time Kinetic (RTK) on-the-fly (OTF) Differen-tial Global Positioning System (DGPS) positioningsystem, this three-dimensional system will give theheight of the DGPS antenna on board of the vesselabove datum (dredger or survey vessel).

Surveys are conducted using a 210 kHz, 33 kHz echosounder as well as a multi beam echo soundertogether with the RTK/OTF DGPS positioning system.In the tunnel trench the survey vessel runs survey linesevery 10 metres perpendicular to the alignment of thechannel, starting and ending each line 60 metres outs-ide of the work area.

The multi-beam echo sounder is calibrated before andafter each survey. The echo sounder is interfaced witha heave compensator in order to reduce the effect ofseas on the soundings. The accuracy of the DGPSposition is monitored by a separate DGPS receiver onshore.


19

Figure 3. Cross-section of the Tunnel Trench at chainage 2630 with the various types of soil to be dredged.

Figure 4. Cutter dredger Castor and gravity anchors in theØresund (photo: Jan Kofod Winther).

pared to previous surveys to verify the accuracy of thesurvey.

The information generated by the sophisticated surveyequipment will guarantee the required accuracy whilstdredging the Tunnel Trench by cutter suction dredgerCastor.

PLANNING

The dredging and reclamation works were started inOctober 1995 and completion of the dredging works ispresently scheduled for August 1997. Immersing ofTunnel Elements will start in the spring of 1997 and isscheduled to finish in the autumn of 1998. Reclamationworks will take up to 1999 whilst completion of theworks is scheduled for April 2000.

The dredging and reclamation project is extremelycomplicated in terms of planning. ØMJV has to opti-mise its planning within a tight scheme of completionmilestones for the different dredging and reclamationareas. Within ØMJV an internal scheme of milestoneshas to be maintained to control the hand-over of workbetween partners.

Due to spill and contractual spill limitations, detailedplanning is difficult. The actual spill is very much effec-ted by seasonal and weather changes. The cold Scandi-navian winters can delay operations for weeks or evenmonths. The uncertainty in soil conditions and conse-quent production rates as well as wear of dredgingequipment has a significant effect on required contin-gencies. Down hours, which were caused by unexpec-ted pipeline failures, are now being avoided by anaccurate monitoring system. More details on OMJV’smethods and research activities to handle these uncer-tainities are provided below.

Planning and progress is monitored closely withinØMJV and reported internally through a system ofprogress meetings and progress reports. A similarsystem is maintained between Øresundskonsortiet and ØMJV. All relevant construction programmes of the contrac-tors are linked through the comprehensively implemen-ted planning programme, Primavera.

SOIL CONDITIONS AND DREDGEABILITY

At the project location two types of materials have tobe dredged and used for reclamation of the artificialIsland. These two types of materials are Limestone andGlacial Deposits both having varying but typical proper-ties.

Glacial DepositsThe youngest and at seabed occurring material is the“Glacial Till” and consists of Clay, Silt, Sand, Gravel,Stones and Boulders deposited by Glaciers during thelatest Ice Age. The Till is overlying the CopenhagenLimestone in about 50% of the project area.

In the Till all grain sizes are present but the grain sizedistribution varies dramatically. The Till may be a veryclayey silt in one place and almost a slightly silty gravelin other places. Big boulders with diameters up to afew metres are present throughout the Glacial Till. The Till is very much overconsolidated with high UnitWeights (up to 24 kN/m3) and Shear Strength values(up to 1 MPa) due to the high overburden pressures ofthe Ice Cap present during the latest Ice Age.

Worldwide experience has been gained dredgingsimilar glacial materials, as well as closer to homewhen these identical materials in the Great Belt for theStorebælt project were dredged. Large back-hoe dredges, dipper dredges and cutterdredges are capable of dredging these materials.The presence of boulders can cause serious productiondelays or additional costs if they become too large tobe handled by the equipment used.

CSD Castor has successfully been dredging Till in theØresund Project area though a number of big bouldershad to be removed separately by a large grab dredge.

Copenhagen LimestoneThe “Copenhagen Limestone” is directly exposed atsea bed or overlain by Glacial Deposits. The Copenha-gen Limestone has been deposited early in the Palaeo-cene about 60 million years ago. The Limestone in the Øresund Project Area consists ofa succession of Limestone Units which are the Lower,Middle and Upper Copenhagen Limestone. Each ofthese units consists of layers of Limestone and Flint.Flint, being micro-crystalline Quartz, occurs both dis-


20

Figure 5. Strict tolerances on the design apply to the TunnelTrench.

has the most intact Rock Mass and hence highestRQD values.

The Tunnel Trench to be dredged as part of the Øre-sund Project represents a volume of 2.2 million m3 ofwhich 1.9 million is Upper, Middle and Lower Copen-hagen Limestone. The depth of the tunnel trench is inplaces up to 12 metre into the Limestone formations.

From a dredgeability point of view the CopenhagenLimestone is at the borderline of what can be dredgedby a cutter suction dredge. Any other type of equip-ment cannot be used to dig the hardest layers withinthe Copenhagen Limestone without the use of explo-sives to break the rock.

Evaluation of the available data indicated that althoughrock strength values are often sometimes high toextremely high, the fracturing and layer thicknessfavour the use of a cutter dredge.

Additional investigations to verify the properties of theCopenhagen Limestone revealed increased percenta-ges of high strength limestone and flint. Also the RockMass properties showed to be better than the tenderinformation indicated.

So far CSD Castor has removed 1 million m3 from thetunnel trench of which a considerable volume was inthe parts which were envisaged to be extremely diffi-

persed in the Limestone matrix and as nodules, bandsor even rather frequent as solid layers.The layers, in which strength properties are relativelyconstant, vary in thickness between typically 5 mm and500 mm. The strength of layers varies between 1 MPafor slightly lithified limestone and 350 MPa for Flintlayers.

The Rock Mass is folded with an amplitude of not morethan 5 metre. Locally faulting occurs with minor dis-placements of not more than 1.5 m. The Rock Masscan be described as fissured with vertical joint spacingvarying between 2 mm and 500 mm with an averageRQD value of 29%.

The Rock Mass is very fissured and sometimes evencrushed in the top 1 to 4 metre. In this part of theLimestone the action of ice has caused significantdisturbance and fracturing and sometimes even mixingwith the glacial materials.

The Copenhagen Limestone has very varying proper-ties in the vertical direction but the lateral continuity ofproperties makes correlation of mechanical propertiesbetween boreholes possible.

The Middle Copenhagen Limestone is the “softest”unit with the lowest UCS and RQD values. The LowerCopenhagen Limestone has extremely well definedthick flint layers and the Upper Copenhagen Limestone


21

Figure 6. One of six cutterheads available at the project prior to being installed to dredge the extremely hard layers of CopenhagenLimestone in the tunnel trench.

cult and it can be concluded that CSD Castor will beable to dig all the material in the tunnel trench.

The productions of the CSD Castor have been opti-mised by adjusting the cut design for the extremelyhard layers in the Copenhagen Limestone (Figure 6). A true 3-D model was established using the boringinformation in combination with advanced geo-physicalborehole logging and seismic interpretation.

Figure 3 gives a cross-section through the tunneltrench chainage 2630. The different colours indicatelayers with different dredgeability classification.

WEAR AND TEAR OF PIPELINES

Before the start of this project, little experience hadbeen gained with the wear of pipelines when dredgingFlint and Limestone. It has been anticipated in thetender stage that severe wear of the pipeline systemcould be expected. In practice the wear at the bottomof a pipeline is varying from 1 mm steel per 20,000 m3

to 100,000 m3. This means that to avoid delays a pipehas to be turned or a pipeline replaced in a timelyfashion.

Economical JustificationThe pipeline system of the cutter suction dredgerconsists of floating pipeline, sinkerpipelines and land-lines. Riser pipelines are used to connect floating pipe-

line, sinkerpipeline and landline. In total there are some10 kilometres of pipeline (submerged and floatingpipeline diameter 850/800 mm and landline 840/800mm) on site, with an installed value of approximatelyNLG 10 million. The breakdown of, in particular, sinker/submergedpipelines can result in delays of days or even weeks ofthe dredging process. The strongly varying sea con-ditions, in particular the currents, in the Øresund disableplanning of activities on the water and therefore cancause long delays. It was therefore decided to monitorthe wear of the pipeline system closely.

Representative MeasurementsMeasurements are done by using a Krautkramer Bran-son DM4 DL acoustic thickness measurement device.A number of measuring points have been defined andprepared, corrosion is removed, and they are coveredby grease to enable accurate measurements. The measurement points are chosen on the wall, sincethe measurements are most easily taken here. From the measurements a wear rate per day is derived.This is used to estimate the status of the rest of thepipeline, which cannot be measured at any time. The estimates of the pipeline status are checked ad-hoc when the pipes are available for measurement.Pipes are both measured from the outside and fromthe inside. The results of the measurements are storedin a database and presented in the form of “statuscircles” to the project staff and instructions to turn orreplace a pipeline can be derived from these circles(Figure 7).

Pipeline Management SystemThe pipeline configuration changes frequently: landpipes are being shifted and extended, floating pipelinesare installed and removed as required. Therefore it isessential, for a good estimation of the status of pipe-lines, to know how many and which cubic metres havebeen pumped through each of the pipeline sections.

This information is stored in the computer database.The database is built up in such a way that per day a listof pipelines can be presented, including bends andspecial pipes, e.g. to connect a booster station in thepipeline system (see Figure 8). Furthermore the data-base can be used to look at the number of cubicmetres that were pumped through the pipeline, forevery turn of the pipeline. This, together with the calcu-lation of a daily wear rate, is used to estimate thestatus of the pipeline.

Wearbed and Economical Use of PipesFigure 9 shows the result of measurement of a floatingpipeline. The wear is concentrated at the bottom 40 cmof the inside diameter of pipeline and is most severe1 m to 3.5 m behind a balljoint. This is caused by theturbulence behind the joints of the floating pipeline.Based on the wear bed it has been decided to turn the


22

Figure 7. The results of the measurements are stored in adatabase and presented in the form of “status circles” to theproject staff and instructions to turn or replace a pipeline canbe derived from these circles.


23

Figure 8. The database is built up in such a way that per day a list of pipelines can be presented, including bends and special pipes,e.g. to connect a booster station in the pipeline system.

Figure 9. The result of measurement of a floating pipeline.

pipeline over 60 degrees, when the bottom side iscritical (approximately 10 mm wall thickness). Thisapplies both to the land lines and the floating pipelines.The submerged pipelines are typically turned over 180degrees or 90 degrees, because of the difficulties tocontrol the position when lowering the pipeline to theseabed.

Prediction of Wear, Velocity and Flint %Existing wear prediction formulas shows that the wearof pipelines is correlated to the type of material, thedensity of material which is pumped through the pipeand to a large degree by the velocity of the material inthe pipeline. The velocity is therefore set, as low aspractical, between 4.5 and 5.5 m/s, by an automatedvelocity control system which is installed at theCSD Castor and the booster stations Kopenhagen andMalmö. The density of the pumped material is low and varieslittle and is approximately 1.10 ton/m3, for the dredgingof limestone and flint. Since the velocity and the densi-ty are relatively constant, the type of material is causingthe differences in wear. Notably the percentage of flint,which is harder then steel, in the material is the deter-mining factor. To be able to predict the status of pipe-lines and to plan the turning and replacing of pipelinesections, the rest of the dredging of works have beendivided in parts of 5000 m3. For each 5000 m3 anestimate of the flint percentages were derived from the

3-D ground model and a prediction of the wear andconsequential activities have been made for eachsection.

Conclusion

The dredging and reclamation work for the ØresundFixed Link must be considered technically as a verycomplicated dredging project. ØMJV is dealing withstrict environmental restrictions, design tolerances andcompletion milestones, and has to manage considera-ble risks in terms of delays caused by soil conditions,wear of pipelines, and difficult weather conditions.

So far, CSD Castor has been able to excavate the hardlayers in the Copenhagen limestone and is expected tocomplete the tunnel trench dredging in the summer of1997. By then the Castor will have completed a pieceof work that must be considered as “high perfor-mance” when related to the type of material dredged,allowable spill, and the acceptable design tolerances.

Down hours, which were caused by unexpected pipe-line failures, are now being avoided by an accuratemonitoring system which enables an economical useof the pipelines exposed to the extremely abrasiveslurry pumped by the Castor.


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Charles W. Hummer, Jr.

Books/PeriodicalsReviewed

Dredging, A Handbook for Engineers, SecondEdition.Arnold Publishing, London, Sydney, Aukland. 1997.434 pp. Illustrated, index and references. UK£75.

R.N. Bray, A.D. Bates and J.M. Land

First published in 1979, this handbook for engineersbecame a standard reference in the dredging field. And this second edition is destined to become knownas today’s “bible” of dredging. In this new edition, theinternational dredging expert, Nick Bray teams up withtwo venerable colleagues, Tony Bates and John Landto give even more depth and prestige to the volume. Since publication of the first edition, there have beenconsiderable technical developments in the dredgingindustry. During the same period, the legislative andenvironmental framework within which dredging isperformed has become better defined and more rigor-ously imposed. Therefore whilst the book is in somerespects an update of the earlier version, it goes farbeyond that in terms of its discussion of environmentalissues and the comprehensiveness with which it dealswith other aspects.

The authors aptly state that the text is intended for twotypes of usage; as a general primer, for those unfamiliarwith the subject, and as a handbook for practitioners. Even for one relatively well versed in the field of dredg-ing, the book’s organisation and presentation is a treat.Some general strengths include the use of flow chartsfor characterising various processes discussed; draw-ings and charts that are clear and legible; good repre-sentative photographs (even in color); and the ability toconvey mathematical concepts without the use ofpages of confusing mathematical equations.

The scope of the subject matter contained in this rel-atively modest-sized book is impressive. Its readability,

INTRODUCTION

When the book review section began, it seemed thateverything that could be reviewed, would be reviewedin a matter of one or two years. The literature relatingto dredging seemed relatively limited in terms of thevolume and frequency of publications.

Now nearly five years and 50 reviews later, it is encou-raging that the field of dredging has produced so manyexcellent publications on all facets of the subject. Our challenge has become to be aware of, acquire, andreview publications that are of value and of interest toour readers.

This issue of Terra is monumental because it reviewstwo publications which are new editions of two of thetrue “Rosetta Stones” of dredging. Both Dredging,A Handbook for Engineers, by Bray, Bates and Land,and Tom Turner’s Fundamentals of Hydraulic Dredgingare amongst the most significant reference works ondredging. Whilst there is some overlap in subjectmatter, they are not redundant, but complementary.

It marks ”the coming of age” of dredging technologythat so many significant publications on the myriadaspects of dredging continue to spring forth. They address both the advances in science as well asthe changes in social emphasis that impact on thephysical world, such as new considerations caused byenvironmental concerns.

In addition to the reviews of these “dredging bibles”,this issue examines other publications on dredging,which typify the progress made in the field and thediscipline of the professional organisations whose goalsare to encourage the exchange of science and tech-nology related to dredging.

Books/Periodicals Reviewed

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for those new to the subject and veterans alike, is agreat asset. The book is organised into 14 chapters andhas an appendix. A review of the chapter titles clearlydemonstrates the extensive treatment of subjectsrelated to dredging. After an introduction (Chapter 1),the book continues with:

Chapter 2 Project Implementation; Chapter 3 Design ofDredging Works; Chapter 4 Use of Dredged Materials;Chapter 5 Disposal of Dredged Materials; Chapter 6Pre-Contract Investigations; Chapter 7 Dredging Plantand Equipment; Chapter 8 Performance of DredgingPlant; Chapter 9 Estimating Output; Chapter 10 Dredg-ing Costs and Prices; Chapter 11 The Dredging Con-tract; Chapter 12 Dredging Works and their Control;Chapter 13 Dredging and the Environment; andChapter 14 Pre-treatment of Rock.

The authors present useful references at the end ofeach chapter. A review of the references gives a spe-cial appreciation for the knowledge base of the materialpresented. Whilst it might have been useful to also listthe references comprehensively in an appendix, inaddition to at the chapter endings, this is a small criti-cism indeed. The book does have a subject index thatis essential to its function as a reference work.

It is worth repeating that the use of flow charts is aparticularly effective tool in presenting the processesdiscussed, be it the need for dredging or tender proce-dures or those shown for the cycles of operations forthe various types of dredging plant. After examining theinitial flow chart, an immediate search of the rest of thebook revealed the valuable presentations in later chap-ters as well. Another point worth mentioning is that the book pro-ceeds logically through the entire scope of dredgingtechnology. The sections dealing with dredging plantand the details of ancillary equipment and instrumenta-tion are notable. Likewise those sections that cover theestimating, dredging costs and contracts are in suffi-cient depth and detail to be both instructional anduseful for both the veteran and newcomer.

One area where few if any books on dredging portrayany meaningful treatment concerns the dredging ofrock or other hard material. The final section of thispublication does a fine job of introducing the reader tosome of the intricacies of rock dredging and the variousaspects related to this specialised field.

Another valuable inclusion is the appendix on theDredged Material Assessment Framework recentlyadopted by the London Convention, the internationalregulatory organisation that deals with, amongst otherthings, the disposal of dredging material in the marineenvironment. The framework and other aspects of thenew international convention on the disposal of dredg-ed material are matters of which all involved with

dredging should be aware. It is a very timely inclusionto the book.If one has anything at all to do with the design, con-struction, approval, financing or maintenance of proj-ects that employ dredging, they should not be withoutthis book. It is indeed a dredging “bible”, and certainlymeets the authors claim of being the most comprehen-sive primer on the subject of dredging.

This book may be obtained from:Bookpoint Limited39 Milton Park, Abingdon Oxon, OX14 4TD, UKorJohn Wiley & Sons, Inc605 Third AvenueNew York, NY 10158-0012, USA.

Fundamentals of Hydraulic Dredging, Second EditionAmerican Society of Civil Engineers Press. New York. 1996. 258 pp. Photographs, tables, figures, references. US$42.00 in the USA; US$62.40 outside the USA.

Thomas M. Turner

Anyone who has been around the dredging industry forany time at all has heard of Turner’s Seven Basic Dred-ge Laws, a rare combination of technology, physics andpresentation that makes the complex concepts ofslurry hydraulics both understandable and friendly. In the United States, Turner is especially known as anexpert, presenter, educator and author, but in therelatively close camaraderie of dredgers around theworld, Tom Turner’s name is synonymous with dredg-ing hydraulics. Turner has been an instructor on dredg-ing hydraulics for the US Army Corps of Engineers andTexas A&M University’s Center for Dredging Studiesfor a number of years.

This book is a significant expansion of his earlier book.Whilst it effectively presents the Seven Basic DredgeLaws with improved figures and narrative, it goes wellbeyond them. The book, as the author states, is inten-ded as a handbook for all involved with hydraulic dred-ges, be they owners, managers, engineers, leverman,or lawyers. The book comprises two major parts: the first elevenchapters deal with the theories of dredging; the remain-ing eleven chapters deal with the practices of dredging.The order of presentation is effective, and for studentsit is a logical sequence to proceed. The book is alsoorganised so it is an effective reference work for thosein the field who will find it a valuable resource on a day-to-day basis.

The first part that is devoted to the presentation of thelaws of dredging serves as a basis for understandingthe complexities of hydraulic flow, pumps and thefactors that relate to the processes. One especially


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This publication may be obtained from:American Society of Civil Engineers345 East 47th StreetNew York, New York 10017-2309, USA

Guidance on the Disposal of Dredged Material toLand. CIRIA Report 157. Construction Industry Research and Information Asso-ciation.London, UK. 1996. 155 pp. Tables, figures, references.

J Brooke et. al.

The Construction Industry Research and InformationAssociation (CIRIA) is a non-profit private sector organi-sation active in the United Kingdom that carries outresearch and provides information for its members,who include all types of organisations concerned withconstruction. Membership includes clients, profession-al practitioners, contractors, suppliers, educational andresearch establishments, professional institutions,trade associations and central and local government.

The implementation of the “Waste ManagementLicencing Regulations” in the UK (specifically, England,Scotland and Wales) in May 1994 served as the impe-tus for the report. Whilst the genesis was founded inthe UK, many aspects of the report apply generally toother jurisdictions and situations. Certainly it is alwaysbeneficial to be aware of regulatory initiatives regardingdredged material and the effects of such regulation. Inthis case the potential impact on other European Unionjurisdictions is likely.

The Waste Management Licencing Regulations aredetailed and complex and will significantly influence thedisposal of dredged material on land. Under the Regula-tions, unless an operator can demonstrate that thematerial is not a controlled “waste” or that the disposaloption meets one of the specified exceptions, a WasteManagement Licence will be required. It is with thisregulatory framework that CIRIA prepared this report togive guidance on the safe, economical and effectivedisposal and management of dredgings. For those inthe UK it is an effective introduction into the complexi-ties of the disposal of dredged material, most of whichis uncontaminated and of natural origin, and the costsassociated with the process.

The report is divided into two parts. The first providesguidance on the selection and planning of a disposalmethod, including the legal position, information requir-ements and application procedures. The second partprovides supporting information to enable the user toapply for a licence or register an exemption. In thesecond part, the first chapter deals with the legislativeand regulatory issues within the UK. The latter chaptersare more generic in terms of subject matter, but all arecast within the context of the regulating jurisdictions.

unique feature of Turner’s Dredging Laws is that theyserve to dispel the many myths that abound in themore empirical or operational side of the business.Many of these myths can result in costly inefficiencies,some of which have continued for generations. So nomatter how long one has been in the dredging industry,if you have not carefully read the Seven Laws, it wouldbe most prudent and productive to do so.

Perhaps a more detailed presentation of the table ofcontents will be helpful to realise the essence of thebook.Part I, Theories of Dredging contains chapters as fol-lows:1. Hydraulics Simplified; 2. Production Rate Calcula-tions; 3. Dredge Efficiency; 4. Hydraulic TransportFactors; 5. Maximum Dredge Production; 6. The Suc-tion Line and Digging Depth; 7. Horsepower vs. LineLength; 8. Production Charts; 9. The Dredge Cycle; 10. Flow Regime and Friction; and 11. Cavitation:Causes and Avoidance.

Part II, Dredging in Practice continues with the follow-ing chapters: 12. Selecting the Dredge Type; 13. The Cutter; 14. The Dredge Pump; 15. Ladder and Booster Pumps;16. Wear in Pumps and Pipelines; 17. Auxiliary Equip-ment; 18. Instrumentation and Automatic Control; 19. Calculating and Bidding the Project; 20. The Person-al Computer in Dredge Management; 21. Operationand Troubleshooting; and 22. The Environment and theDredge.

Clearly, the book covers a broad range of materialrelated to the hydraulic dredge and dredging opera-tions. One will find it difficult to encounter a moreunderstandable treatment of such subjects as cavita-tion, the use and value of ladder pumps and wear inboth pumps and the pipelines. These are realities thatmany more theoretical treatises fail to cover in anysubstance, but can be costly elements in a dredgingproject. The increasing value of the use of personal computersin dredging management and engineering is anotherarea that is emphasised. Being aware of the utility ofcomputers and specialised software is important andcan lead the reader to find solutions otherwise notapparent. This section is not, nor is it intended to be, acomplete treatment of the subject, but it underlines theincreasing value of computers in dredging technology. Finally, the section on the environment capsulisessome more philosophical than technical aspects relatedto dredging and the environment, but the capsulepretty well hits the nail on the head or heads as thecase may be.If one were to have to settle on only two books in yourdredging library, this book plus the Bray, Bates andLand Dredging. Handbook for Engineers are the tworecommended.


27

The report contains a series of decision flow chartswhich are very useful for understanding the variousprocesses involved. They portray graphically the some-times intricate steps and concepts required by theregulations and the gathering of information to satisfythe regulatory and technical requirements. Likewise,there are some very useful checklists, that, used inconjunction with the flow charts, are very helpful ininsuring that all factors are being considered as oneproceeds through the process. The publication tends to be somewhat bureaucratic inits presentation. That may be attributable to the regula-tory origins of the report and the complexities of thetechnical and procedural processes involved. There issome good general guidance regarding the characteri-sation of dredging material, the chemical contaminantsampling and limits in existence in some jurisdictionsand the continuing struggle between environmentaleffects based testing and regulation and the morelimiting ”sediment standards” or set limits for specificcontaminants regardless of all other factors that exist ina natural setting.

Perhaps the following conclusion quoted from thereport typifies the uneasy feeling one is left with whenreviewing the report: “The Waste Management Licencing Regulations haveproduced a complex legal and administrative frame-work for regulating the disposal of dredgings.....Although conventional definitions and standards will beestablished with the passage of time, it is likely thatonly litigation will provide definitive answers to somequestions of interpretation”.

Whilst the publication is definitely directed to the UKdredging situation and will find its best use in that area,it should be of interest to regulators and scientists inother jurisdictions.

The publication may be obtained from:CIRIA6 Storey’s GateWestminster, London SW1P 3AU, UKemail: [email protected]

Environmental Aspects of Dredging, Proceedings ofCEDA-EuDA Seminar.4 September 1996, Gdansk, Poland. Central DredgingAssociation. Delft, The Netherlands. 1996. Illustrated, tables, figures, references.

CEDA/EuDA

This publication is actually a compendium of tutorialsand appendices from a seminar sponsored by theCentral Dredging Association (CEDA) and the EuropeanDredging Association (EuDA) presented in Gdansk,Poland in September 1996. The seminar was held inconjunction with the International Conference on Inland

and Maritime Navigation and Coastal Problems ofCentral and East European Countries.

The seminar was a landmark event in and of itself as ademonstration of the success of both CEDA and EuDAin collaborating on the primary objective of furtheringdredging technology. The publication constitutes theproceedings of the seminar and served at a textbookfor the attendees. The four tutorials are:1. Dredged Material Disposal in the Sea by

T. Neville Burt and Caroline A. Fletcher2. The Dredging Operation by G.H. van Raalte3. Beneficial Uses of Dredging Material by

H. Glindeman and A. Csiti4. Environmental Aspects of Dredging in Ports:

The Project View by F. J. Mink

The appendices provide some very useful referencesrelating to the environmental aspects of dredged dis-posal:Appendix 1. London Convention 1972; ArticlesAppendix 2. London Convention 1972; Dredged

Material Assessment FrameworkAppendix 3. DEBBY; Dredging and Environmental

Database

The tutorials are summaries that highlight the subjectmatter and the issues. They are an excellent means bywhich to easily acquire an introduction to these issues,which are so important to dredging specifically, and tonavigation and the national economies in general.

The first paper, “Dredged Material Disposal in theSea”, does a fine job of presenting the background andconcepts of the London Convention of 1972 and theOslo and Paris Conventions, all of which deal with thedisposal of wastes in the marine environments. Thepaper emphasises dredged material as the so-called“waste” being disposed. The new developments inthe London Convention such as the “precautionaryapproach”, the Dredged Material Assessment Frame-work as well as the basics for assessment of dredgedmaterial, assessment and selection of disposal sites,and the importance of monitoring are presented in areadable summary. This is very useful for the beginner,or person being introduced into the issues related todredging. (This paper in an updated version is reprintedstarting on page 3 of this issue of Terra.)

The second paper, “The Dredging Operation”, dealswith the dredging process and the equipment used fordredging. It describes the various types of dredges andtheir utility. The paper then discusses the environmen-tal effects of dredging projects and the environmentalrequirements for dredging operations. A short descrip-tion of special techniques, equipment and practices,project monitoring and control, and the environmentalaspects of planning in dredging projects rounds off thesubject.


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– Management of dredged material in Germany -- acompromise between economy and ecology.

– Development of a cost calculation module for theinland and sea-river waterway transport.

- Crossing of navigable rivers and waterways bypipeline systems.

– Wind effects on sediment transport in river mouth.– Assessment of the effect of the shipbuilding indus-

try upon the pollution of the sediments in the har-bour basins and canals.

– The influence of transportation policy upon thedevelopment of waterways and inland navigation inPoland.

– Inland Navigation in Hungary.

A review of the papers indicates that some are particu-larly significant and within the strict boundaries of thetitle of the conference. Other papers go more afield butare of interest because they portray a subset of issuesand problems related to the broader conference title ofmaritime navigation.

The proceedings are the first available in English whichreflect the contemporary experience and situation inEastern Europe. They can provide valuable insight forconsultancies or contractors regarding market potentialand the nature of technical problems facing thesechallenged economies.

This publication may be obtained from:Secretariat, Central Dredging AssociationP.O. Box 31682601 DD Delft, The Netherlandsemail: [email protected]

“The Beneficial Uses of Dredged Material”, the thirdpaper, not only presents the theory and principles ofusing dredged material as a resource, it also givessome examples of case studies for the beneficial use inEurope for both uncontaminated and contaminatedsediments.Finally, the last paper, “Environmental Aspects ofDredging in Ports: The Project View”, is a short over-view of the reasons ports and port dredging haveenvironmental consequences, the types of pollution oftoxic materials generally encountered, categorisation ofsediments, an excellent flow chart on the decisionsteps in preparing a dredging project and the conceptof “Best Environmental Practice”.

The appendices are useful references to the interna-tional regulatory aspects of the disposal of dredgedmaterial at sea and the availability of the computerdatabase developed collaboratively for the LondonConvention on Environmental Aspects of Dredging. This is an effective introductory publication that shouldfind many uses amongst many audiences. As anadjunct to the international conference, this publicationprovided a very effective preface to the complex issuesfacing the Central and Eastern European countries.

This publication may be obtained from:Secretariat, Central Dredging AssociationP.O. Box 31682601 DD Delft, The Netherlandsemail: [email protected]

Proceedings from the Inland and Maritime Navigationand Coastal Problems of East European Countries.Environmental Aspects of Dredging, Volumes 1 and 2.Technical University of Gdansk, Poland, September1996. 592 pp. Both volumes.

B.K. Mazurkiewicz, Editor

These two volumes are a major step forward in begin-ning the long path towards addressing the problems ofdredging as they relate to the East European Countries.The conference was hosted by the Technical Universityof Gdansk under the sponsorship and cooperation withthe Permanent International Association of NavigationCongresses (PIANC) and the Central Dredging Associa-tion (CEDA).

The proceedings contain 46 papers representingauthors from 18 countries. The papers cover a broadspectrum of subjects, some experiential, others theo-retical and still others economic. A sampling of thepaper titles is as follows:– Discharges of nutrients and contaminants from

Poland versus environmental state of the Polishmarine areas.

– A throughput analysis of the approach fairway to theharbour.


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Seminars/Conferences/EventsMaritime Vietnam ’97

International Exhibition & Convention CentreHo Chi Minh City, Vietnam

April 16-18 1997

Reflecting the emergence of Vietnam as an importantmarket and coupled with her becoming the seventhmember of ASEAN, Maritime Vietnam 97 is co-organ-ised by the Vietnam Chamber of Commerce and Indus-try (VCCI) and is supported by the Vietnam NationalMaritime Bureau. Following up on the success of the1996 event, investments are being made Vietnam inthe development of port facilities, deep seaports,export processing zones (EPZ), ship repair, dredging,ship and marine equipment and so on. The VietnamMaritime & Inland Shipping Exhibition incorporatesVietnam Port ’97.

The 2nd Asian and Australasian Ports and HarboursConference, organised by the EADA, CEDA, IADC andVinamarine is being held in association with theMaritime Vietnam ‘97 (see below).

For further information contact:RAI Exhibitions Singapore Pte Ltd1 Maritime Square, #09-01World Trade Centre, Singapore 099253tel. +65 272 2250, fax +65 272 6744

Amsterdam RAI, P.O. Box 777771070 MS Amsterdam, The Netherlandstel. +31 (20) 549 1212, fax +31 (20) 646 4469

2nd Asian and Australasian Ports and HarboursConference

International Exhibition and Convention CentreHo Chi Minh City, Vietnam

April 16-18 1997

This conference, organised by the Eastern DredgingAssociation (EADA) in association with the CentralDredging Association (CEDA), the International Associa-tion of Dredging Companies (IADC) and Vinamarine, isbeing held in association with the exhibition MaritimeVietnam ’97.

The theme of the conference is “Developing andMaintaining Operational Ports and Harbours into the21st Century”. The response to the Call for Papers has come from allover Europe, Asia and the USA, and some 40 papers ofexcellent quality on a wide variety of subjects will bepresented. Please see the Registration Form on thefollowing page.

For an update about the Conference visit:http://www-tt.wbmt.tudelft.nl/ceda/main.htm

For further information contact: Mr J.F. DobsonSecretary EADA Technical Paper CommitteeGPO Box 1818, Brisbane, Q4001, Australia tel. +61 7 3258 4746, fax +61 7 3258 4704, or

Dr A. Csiti, Manager, CEDAPO Box 3168, 2601 DD Delft, The Netherlandstel. +31 15 278 3145, fax +31 15 278 7104

Marine IndonesiaJakarta International Exhibition Centre

Kemayoran, Jakarta, IndonesiaApril 23-26 1997

The expansion and development of Indonesia’s marineindustry is now critical. With increases in containertraffic and recent deregulation to attract massive priva-te investiment the time is ripe for expandsion of exis-ting port facilities and the development of port-relatedinfrastructure projects. For these reasons, MarineIndonesia will attract an international audience both asmajor exhibitors and as visitors.

For further information contact:PT Pamerindo Buana AbadiBank Bumi Daya Plaza, Unit 2102, 21st FloorJl Imam Bonjol 61, Jakarta 10310, Indonesiatel. +62 21 325560, fax +62 21 330406

Marie Waters, Overseas Exhibition Services Ltd.11 Manchester Square, London W1M 5AB, UKtel. +44 171 486 1951


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Seminars/Conferences/Events

31

International Exhibition and Convention Centre, Ho Chi Minh City, Vietnam, April 16-18 1997

Economic growth and trade in the Asian and Australasian region call for ports and harbours to be pro-active in planning, managing and maintaining their port infra-structure. This EADA Conference in Vietnam will bringtogether people to share information about the latest designs and techniques for dredging, reclamation,navigational aids, surveys and marine structures. To register please fill in the form below.

The 2nd Asian and Australasian Ports and Harbours Conference:

Developing and Maintaining OperationalPorts and Harbours into the 21st Century

REGISTRATION FORM

(Please TYPE or use BLOCK LETTERS and UNDERLINE the LETTER under which your name should be alphabetised)

Family Name: ................................................................ First name/initials: ....................................................................................Title/Position/Appointment: ...............................................................................................................................................................Organisation/Company: .....................................................................................................................................................................Postal Address: ..................................................................................................................................................................................Postal Code: ....................................................... Town: ...................................................................................................................State: .................................................................. Country: ...............................................................................................................Telephone: .................................... Telefax: ......................................... E-mail: ...............................................................................Preferred name for badge: ................................................................................................................................................................Accompanying person (Name for badge): ........................................................................................................................................If applicable, I am a member of: ▫ EADA ▫ CEDA ▫ WEDA

I wish to register for the 2nd Asian and Australasian Ports and Harbours Conference, te be held at the International Exhibition and Convention Centre, Ho Chi Minh City, Vietnam, 16-18 April 1997.I also like to receive:• Details of programme for Accompanying Persons ▫ Yes ▫ No• Details of Pre/Post Conference Tours ▫ Yes ▫ No• Details on the Matchmaking Programme ▫ Yes ▫ No• Details of Exhibition Participation ▫ Yes ▫ No• Please register me for the site visit on Saturday morning ▫ Yes ▫ No• Please send me the Visa Application Form ▫ Yes ▫ No

Hotel reservation: Please indicate your preference and details:Hotel: 1st Choice: ................................................ 2nd choice: .........................................................................................................Check-in date: ...................................................... Room Type: ▫ Single ▫ TwinCheck-out date: ...................................................Note: To guarantee room reservation, please provide your credit card details:

Card no. ........................................ Amex / Diners / Eurocard / Mastercard / VisaExpiry date:................................... Signature: ....................................................................................................................

Registration fees:• Author of technical paper US$ 400 US$:.............................................................................• Member of EADA, CEDA, WEDA US$ 450 US$:.............................................................................• Vietnamese participants US$ 50 (Vin Dong 56,000) US$:.............................................................................• All others US$ 500 US$:.............................................................................• Partners programme US$ 70 US$:.............................................................................• An (extra) copy of the Proceedings US$ 70 US$:.............................................................................

Total payment in US$: ............................................................................Mode of payment:Bank transfer to: Bank name ABN-AMRO Bank, Branch Kneuterdijk

Address: PO Box 155, 2501 AM The Hague, The NetherlandsPayees name: EADA Conference VietnamAccount no.: 40.46.80.100, Bank swift code: ABN.ANL.2R

Cheque/Bank draft enclosed: No. ................................................................................................................................Please charge my credit card: ▫ Amex ▫ Eurocard ▫ Mastercard ▫ Visa ▫ Diners Club

Card no.: Expiry date:

Signature: .............................................................................................. Date: .................................................................................Please return this formby fax: +65-355 1575by mail: Ban & Chan Communications Pte Ltd, 16D Lorong Ampas, G.S. Building, Singapore 328778For your information you may call: +65 355 1574


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fax +44 171 486 8773/ +44 171 413 8222 email: [email protected]: http//www.montnet.com

International Practice SeminarSS Great Britain, Bristol, UK

May 10 1997

The Hydrographic Society is convening a one-dayseminar on International Practice to be held aboard theSS Great Britain. The event marks The Society’s 25thanniversary and will be followed by a celebratorybanquet.Seminar proceedings will deal with key internationalpolicy issues affecting hydrographic surveying includingconsultancy, professional indentity, copyright, liabilityand negligence.

For further information contact:David Goodfellow23 Derby AvenueLondon N 12 8DD, UKtel. +44 181 445 3453, fax+44 181 446 8986

International Conference on Contaminated SedimentsCongress Centre “De Doelen”

Rotterdam, The NetherlandsSeptember 7-11 1997

The International Conference on Contaminated Sedi-ments (ICCS) is an excellent opportunity for govern-ments, port authorities, the industry and academia topresent and discuss their problems with and solutionsfor contaminated sediments. Subjects will include,national policies and strategies; site investigations; thefate of contaminants; physico-chemical analysis; risksand quality criteria; ecological effects, management andcontrol; treatment technologies (in situ and ex situ);disposal of dredged material; beneficial uses of dredg-ed material; and source control strategies.

For further information please contact the conferencesecretariat:Van Namen & WesterlakenCongress Organization ServicesP.O. Box 1558, 6501 BN Nijmegen, The Netherlandstel. +31 24 323 4471, fax +31 24 360 1159

Pacific Coasts and Ports ’97 Christchurch Convention Centre

Christchurch, New ZealandSeptember 7-11 1997

The purpose of the conference is to provide an inter-national forum for coastal, ocean, port and harbour,

engineering, scientific and management issues. Topicswill include: coastal oceanography and meteorology;coastal sediment processes; shore protection; coastalstructures and environment; harbours and ports; andcoastal zone management. Five well-recognised key-note speakers have been invited from Australia,Canada, Japan and the USA. The conference is being organised by the New ZealandCoastal Society incorporating the 13th AustralasianCoastal and Ocean Engineering Conference and the6th Australasian Port and Harbour Conference.

For further information please contact:Megan O’BrienConference Innovators, P.O. Box 10330Christchurch, New Zealandtel. +64 3 379 0390, fax +64 3 379 0460email: [email protected] or visit the conference website athttp://www.cae.canterbury.ac.nz/coastal/pacific.htm

Offshore Europe ’97Aberdeen Exhibition and Conference Centre

Aberdeen, ScotlandSeptember 9-12 1997

This Oil and Gas exhibition and conference is organisedby the Offshore Europe Partnership -- a partnershipbetween Spearhead Exhibitions Ltd and the Society ofPetroleum Engineers. The theme of the conference is“Continuous Change -- Learning from the 21stCentury”. Technical papers and panel discussions areplanned on: Time to Market; Commissioning andDecommissioning; Exploration: Deeper Water, Deeper Targets; Innovative Technology; ReservoirManagement; Beyond CRINE.Abstracts are welcomed before January 13, 1997. For further information contact:Val Johnston-Jones, Society of Petroleum Engineers4 Mandeville Place, London W1M 5LA, UKtel. +44 171 487 4250, fax +44 171 487 4229email: [email protected]

Exhibitors include manufacturers or vendors of hard-ware or providers of services relevant to the technicaland operating management of offshore oil and gasexploration and production companies, drilling contrac-tors, and offshore engineering contractors.

For information about the exhibition contact:Offshore Europe PartnershipOcean House, 50 Kingston RoadNew Malden, Surrey KT3 3LZ, UKtel. +44 181 949 9222, fax +44 181 949 8168/8193email: [email protected]

AfricaBoskalis South Africa (Pty.) Ltd., Capetown, South AfricaBoskalis Togo Sarl., Lomé, TogoBoskalis Westminster Cameroun Sarl., Douala, CamerounDredging International Services Nigeria Ltd., Lagos, NigeriaHAM Dredging (Nigeria) Ltd., Ikeja, NigeriaNigerian Dredging and Marine Ltd., Apapa, NigeriaWestminster Dredging Nigeria Ltd., Lagos, NigeriaZinkcon Nigeria Ltd., Lagos, Nigeria

The AmericasACZ Marine Contractors Ltd., Brampton, Ont., CanadaBeaver Dredging Company Ltd., Calgary, Alta., CanadaDragamex SA de CV, Coatzacoalcos, MexicoGulf Coast Trailing Company, New Orleans, LA, USAHAM Caribbean Office, Curaçao, NANorham/Consub S.A., Rio de Janeiro, BrazilStuyvesant Dredging Company, Metairie, LA, USAUscodi, Wilmington, DE, USA

AsiaBallast Nedam Malaysia Ltd., Kuala Lumpur, MalaysiaBallast Nedam Dredging, Hong Kong Branch, Hong KongBoskalis International BV., Hong KongBoskalis International Far East, SingaporeBoskalis Taiwan Ltd., Hualien, TaiwanDredging International N.V., Hong KongDredging International N.V., SingaporeFar East Dredging Ltd., Hong KongHAM Dredging (M) Sdn Bhd, Kuala Lumpur, MalaysiaHAM East Asia Pacific Branch, Wanchai, Hong KongHAM Singapore Branch, SingaporeHAM Taiwan Office, Taipei, TaiwanHAM Thai Ltd., Bangkok, ThailandJan De Nul Singapore Pte. Ltd., SingaporeMumbai Project Office, Mumbai, IndiaPT Penkonindo, Jakarta, IndonesiaTideway DI Sdn. Bhd., Selangor, MalaysiaVan Oord ACZ B.V., Dhaka, BangladeshVan Oord ACZ B.V., Hong KongVan Oord ACZ B.V., SingaporeVan Oord ACZ Overseas B.V., Karachi, PakistanVomsi India Ltd., New Delhi, IndiaZinkcon Marine Malaysia Sdn. Bhd., Kuala Lumpur, MalaysiaZinkcon Marine Singapore Pte. Ltd., Singapore

Middle EastBoskalis Westminster Al Rushaid Ltd., Dhahran, Saudi ArabiaBoskalis Westminster M.E. Ltd., Abu Dhabi, UAEDredging International N.V., Middle East, DubaiDredging International N.V., Tehran Branch, Tehran, IranGulf Cobla (Limited Liability Company), Dubai, UAEHAM Dredging Company, Abu Dhabi, UAEHAM Saudi Arabia Ltd., Jeddah, Saudi ArabiaJan De Nul Dredging, Abu Dhabi, UAEVan Oord ACZ Overseas BV., Abu Dhabi, UAE

AustraliaCondreco Pty. Ltd., Sydney, NSW, AustraliaDredeco Pty. Ltd., Bulimba, QUE., AustraliaJan De Nul Australia Pty. Ltd., Brisbane, QUE., AustraliaNew Zealand Dredging & General Works Ltd., WellingtonVan Oord ACZ B.V., Victoria, AustraliaWestHam Dredging Co. Pty. Ltd., Sydney, NSW, Australia

EuropeACZ Ingeniører & Entreprenører A/S, Copenhagen, DenmarkAnglo-Dutch Dredging Company Ltd., Beaconsfield,United KingdomA/S Jebsens ACZ, Bergen, NorwayAtlantique Dragage S.A., Nanterre, FranceBaggermaatschappij Boskalis B.V., Papendrecht, NetherlandsBaggermaatschappij Breejenbout B.V., Rotterdam, NetherlandsBallast Nassbaggergesellschaft, Hamburg, GermanyBallast Nedam Dredging, Zeist, NetherlandsBallast Nedam Dragage, Paris, FranceBoskalis Dolman B.V., Dordrecht, NetherlandsBoskalis International B.V., Papendrecht, NetherlandsBoskalis Oosterwijk B.V., Rotterdam, NetherlandsBoskalis Westminster Aannemers N.V., Antwerp, BelgiumBoskalis Westminster Dredging B.V., Papendrecht, NetherlandsBoskalis Westminster Dredging & Contracting Ltd., CyprusBoskalis Zinkcon B.V., Papendrecht, NetherlandsBrewaba Wasserbaugesellschaft Bremen mbH, Bremen, GermanyCEI Construct NV, Afdeling Bagger- en Grondwerken, Zele, BelgiumDelta G.m.b.H., Bremen, GermanyDraflumar SA., Neuville Les Dieppe, FranceDragados y Construcciones S.A., Madrid, SpainDravo S.A., Madrid, SpainDredging International N.V., Madrid, SpainDredging International N.V., Zwijndrecht, BelgiumDredging International Scandinavia NS, Copenhagen, DenmarkDredging International (UK), Ltd., Weybridge, United KingdomEnka-Boskalis, Istanbul, TurkeyEspadraga, Los Alcázares (Murcia), SpainHAM Dredging Ltd., Camberley, United KingdomHAM, dredging and marine contractors, Capelle a/d IJssel,NetherlandsHAM-Van Oord Werkendam B.V., Werkendam, NetherlandsHeinrich Hirdes G.m.b.H., Hamburg, GermanyHolland Dredging Company, Papendrecht, NetherlandsImpresa SIDER SpA., Rome, ItalyJan De Nul N.V., Aalst, BelgiumJan De Nul Dredging N.V., Aalst, BelgiumJan De Nul (U.K.) Ltd., Ascot, United KingdomNordsee Nassbagger- und Tiefbau GmbH, Wilhelmshaven,GermanyN.V. Baggerwerken Decloedt & Zoon, Brussels, BelgiumPhilipp Holzmann Aktiengesellschaft, Hamburg, GermanyS.A. Overseas Decloedt & Fils, Brussels, BelgiumSider-Almagià S.p.A., Rome, ItalySkanska Dredging AB, Gothenborg, SwedenSociedade Portuguesa de Dragagens Lda., Lisbon, PortugalSociedad Española de Dragados SA., Madrid, SpainSocietà Italiana Dragaggi SpA. “SIDRA”, Rome, ItalySociété de Dragage International “S.D.I.” S.A., Marly le Roi, FranceSodranord SARL, Paris, FranceTideway B.V., Breda, NetherlandsVan Oord ACZ B.V., Gorinchem, NetherlandsVan Oord ACZ Ltd., Newbury, United KingdomVan Oord ACZ B.V., Zwijndrecht, BelgiumVolker Stevin Baggermaatschappij Nederland B.V.,Rotterdam,NetherlandsVolker Stevin Dredging B.V., Rotterdam, NetherlandsWasserbau ACZ GmbH, Bremen, GermanyWestminster Dredging Co. Ltd., Fareham, United KingdomZanen Verstoep B.V., Papendrecht, NetherlandsZinkcon Contractors Ltd., Fareham, United KingdomZinkcon Dekker B.V., Rotterdam, NetherlandsZinkcon Dekker Wasserbau GmbH, Bremen, Germany

Membership List IADC 1997Through their regional branches or through representatives, members of IADC operate directly at all locations worldwide.

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