22 Terra et Aqua | Number 104 | September 2006

PORT 2000, LE HAVRE’S NEW CONTAINERTERMINAL: BREAKWATERS AND DREDGINGOF THE NAUTICAL ACCESS CHANNEL

JAN VANDENBROECK

ABSTRACT

The construction of Port 2000, at Le Havre,France marks a significant expansion ofFrance’s largest port and the fifth largest inEurope. To facilitate the elaborate expansionplans, the project was divided into severalphases. These included dredging of an accesschannel, construction a 10 km protectivebreakwater, building quay walls anddredging a basin on the river side of theport. In addition two beaches were createdand two caissons were manufactured,towed and sunk.

Flexibility in the execution of the works wasnecessary, as environmental and economicissues arose. The original plans wereadapted to mitigate environmental impactsin the Seine Estuary and to maximise there-use of dredged material. The innovativedevelopment of the accurate dynamicallypositioned and automatically guidedspraying pontoon Bayard II was of crucialimportance. Being ready and able to takeadvantage of good weather conditions wasalso essential as the Channel can be hostilewith heavy swells. In addition, because ofthe presence of ordnance from World War IIsite investigation was required before workcould commence.

Port 2000 is expected to have long-lastingeconomic impact on the development ofcontainer shipping and transshipments inthe northern European area.

INTRODUCTION

As the first and the last port of call on theHamburg, Germany to Le Havre, Franceshipping route, the French port of Le Havreneeds a deep draught for welcoming thenewest generation of vessels, for bothinbound and outgoing traffic. Located 365 kmfrom Paris at the mouth of the Seine Estuary,the port of Le Havre is the largest containerport of France and the fifth largest innorthwestern Europe (Figure 1). Existingcontainer terminals at Le Havre have reachedtheir maximum capacity and some are builtbehind the François I lock making them lessaccessible for larger ships. The increase ofscale of container vessels and the ever strictertime schedules and throughput timesprompted authorities to decide to constructa completely new port. The site chosen is

south of the existing facilities, and is in aplain estuary subject to tidal movementsand directly facing the sea swell.

CONTRACT

In late August 2001, the Le Havre PortAuthority (PAH) awarded the main contractfor the construction of Port 2000 to a jointventure comprising Dredging International,GTM Terrassement (pilot), CampenonBernard TP and Vinci Grands Projets. The aim of this project, as far as the “wet”side is concerned, was the construction ofthe inner and external breakwaters and the dredging of the maritime access andinternal channel of the new container port.The contract was awarded for an amountof € 218 million including eight options fora total of € 103 million of which four morewill be awarded later. The project wasinitially scheduled for 37 months and wasfinalised in 47 months, taking into accountthe elaborate permitting procedures thatwere encountered and that final dredgingoperations were postponed in agreementwith the Port Authorities.

The original Joint Venture offer was withheldowing to the introduction of alternative

Above, Figure 1. The Port of Le Havre at the mouth of

the Seine is the largest port in France, but expansion

was necessary to accommodate the ever-larger

container vessels.

Port 2000, Le Havre’s New Container Terminal: Breakwaters and Dredging of the Nautical Access Channel 23

schedules to minimise the environmentalimpact of the works on the Seine Estuary.In addition, other optimal economicsolutions were sought. In this respect, fine-tuning the phases of execution, themaximising the re-use of dredged material,and the innovative development of theaccurate, dynamically positioned andautomatically guided spraying pontoonBayard II have been of crucial importance.Alternative and beneficiary executionmethods presented to the client, wereclearly decisive in obtaining the contract.

During the first few years of the 21st century,the construction of Port 2000 was thebiggest maritime undertaking in Europe.Construction was completed late in 2005(Figure 2). Remarkably it was exactly acentury earlier that the extension of theport of Le Havre had been begun by anumber of Belgian-based companies. On March 30 2006, the new port wasinaugurated, and reportedly there has been

an increase in vessels calling and incontainer movements per call. Ultimatelythe new facilities will triple containerthroughput to 6 million TEU per year.

SCOPE

The Nautical Access Channel The nautical access channel to Port 2000 isdredged to a level of –16m CMH whichallows a tide-independent access for thelargest container vessels. The access routecomprises:– An exterior channel of 4000 m

presenting a bottom width ranging from580 m at its connexion with the existingentrance channel up to 300 m at theentrance of the new harbour.

– An internal channel protected by thesouthern breakwater, having a length of 4000 m as well and a bottom widthof 300 m.

– A turning circle with a radius of 353 m.

Channel slopes vary from 5/1 for theexterior channel and 3/1 for the internalchannels.

The total dredged volume was over 45 million m3, principally sand and silexgravel. Where possible dredged materialhas been reused as reclamation material(11 million m3) and to construct thefoundations and the core of over 10 km of breakwaters (6 million m3 of gravel). A disposal site for the rest of the materialswas available at the offshore site ofOcteville.

BreakwatersThe southern breakwater forms the mainprotection of the new port over a length of5900 m. It is a sloped dike constructed ona 50-m wide sub-base realised in dredgedgravel. The external protection is completedon the north side by the northern breakwater(300 m), which is linked to the existingconcrete breakwater of Le Havre (Figure 3).

Figure 2. A schematic drawing of the completed Port 2000.

Bunds 3660 m long were realised on thenorthern side to limit the future platformsbehind the quays. These bunds will bereplaced in the future by quay walls, as the container terminals are expanded.Four quays were actually constructed over a total length of 1400 m, eight more are to be constructed in future contracts. The construction of the quay wall was partof a specially dedicated contract, assignedto a civil contractor.

Inner bunds and outer breakwaters areessentially composed of a core of dredgedgravel, covered by a watertight layer andprotected by several layers of quarry rocks.The southern breakwater has in its mostexposed sections an outer protection madeof Accropodes®.

BeachesAs an added, perhaps surprising, plus pointthe new harbour includes two reclaimed gravelbeaches. The first, called “internal beach” issituated just behind the northern externalbreakwater. Its major purpose is to createan ecologically interesting area to sustain amarine plant called “crambe maritima” whichwere threatened by the extension works.

The second beach, situated at the outer sideof the same northern breakwater, is createdto ameliorate the wave climate at the newport entrance. It should absorb a complex

superposition of waves created by diffractionin the new channel and reflection on existingvertical walls.

“Musoirs”Musoirs is the French word for the twoconcrete caissons, placed at the entrance of the port, marking the northern andsouthern sides. These massive structures(surface: 55 m x 21.5 m x height 30 m)were imposed to reduce the opening at theentrance to 300 m so as to limit internalwave action (Figure 4).

Theoretically, a dike formation could havebeen created to protect of the fairway.Unfortunately this would have requiredsuch an acute slope that a much wider portentrance would have been needed. And awider port entrance would increase wavemovements, agitation and turbulencewithin the inner port that would havedecreased port safety beyond acceptablelimits. Hence it became clear that a verynarrow entrance, which could not be realisedwithout the huge caissons, was preferable.

For the major part the caissons wereconstructed in a drydock in the innerharbour, and then set afloat, towed andsunk on location onto prepared gravelbases between –17 m and –20 m CMH.This unusual part of the project will bediscussed more thoroughly below.

WORKING IN PHASES

From the preliminary studies onwards, the Port Authority was fully aware that the phasing of the works would have amajor impact on the sedimentologicalevolution of the estuary during and evenafter the completion of the works. The Port Authority had to consider thatdiminishing the width of the estuary at theheight of Port 2000 by 20 percent, wouldhave a significant influence on floodchannel displacements and resultingerosions, as well as sand displacement anddeposits. In addition, this is an ecologicallyand also economically valuable areabecause of the presence of the entrancechannel to the port of Rouen 100 kminland on the Seine.

The 776 km long Seine river discharges intoone of the largest estuaries of northwesternEurope, a 30,000-ha maritime, industrial andwetland area spanning more than 5 kmwhich includes both the mouth and thefairway to the port of Rouen. The averagedischarge of 500 m3/s, the important tidalrange of up to 8 m, and very strong currentscause a huge sedimentation transport. This, incidentally, moves the mouth of theestuary westward at a rate of 50 m per year.

For these reasons, “phasing the works”was a serious issue for the Joint Venture

Figure 3. An aerial view of Port 2000 with the reclaimed land and protective quay wall under construction.

JAN VANDENBROECK

graduated as a Civil Engineer (MSc) from

the State University Ghent, Belgium.

He joined DEME in 1989 and has worked

as desk operations manager and project

manager on numerous projects. From

2001-2005 he was co-project manager

Marine Works PORT 2000 Le Havre

(France) for the DPAM Joint Venture

(GTM / DI). Since 2005 he is Resident

Manager of Société de Dragage

International (SDI), Lambersart, France.

Port 2000, Le Havre’s New Container Terminal: Breakwaters and Dredging of the Nautical Access Channel 25

further bunds could be realised with thisgravel. This was continued till a maximumdistance was reached between dredgingarea and the bund realisation. At a distanceof longer than 750 m the economical andtechnical advantages of directly pumpinggravel decreased significantly, because ofthe massive pump capacity required for thetransport of the gravel.

At the same time on the western part ofthe channel an access channel was created,requiring small hopper dredgers with limiteddraughts as the area was very shallow. In alater phase the channel permitted the useof bigger (and more economical) hopperdredgers. It also allowed the transport of 3 million m3 of gravel present on thewestern area to be imported to underwaterstock areas as close as possible to thewestern bunds and dikes to be constructed.This allowed direct pumping from thesestocks by cutter suction dredgers into thegravel basement in a second phase.

Once the inner bunds were realised andsufficient gravel stored by the hopperdredgers in the underwater stock areas, a new phase was started: the construction ofthe western sub-base. The two underwaterstock areas had a total capacity of no lessthan 3 million m3. In order not to obstructtotally the flood currents, only the sub-basewas constructed in this phase; the upperdike construction was started severalmonths later.

The sub-base reaching +3 CMH was sub-merged at high water. This means that only a part of the flood is deviated. The creationof this barrier has as a natural consequencethe deviation of the flood stream and thecreation of a new flood channel, south of thesouthern breakwater. The partial deviationcombined with a close follow up of thisevolution allowed a continuous assessment ofthe evolution of the estuary and the possibilityto adapt the phasing whenever required.

One of the economic risks was the displace-ment of huge quantities of sediment andtheir deposit in the navigation channeltowards Rouen. Therefore this floodchannel creation was “accompanied” bydredging works along its path, removingthe sediments in a controlled way anddisposing of them outside of the estuary onthe site of Octeville. A complementarymeasure with the same objective was the 750 m elongation to the west of thesubmersible dikes on the north side of the same navigation channel.

Once the western foundation was realised,the upper dikes were constructed, using atemporary access dike in the middle of theport. This allowed work to be donesimultaneously to the east and to the westthus accelerating the construction process.The total length of the protection dikes was5.9 km, to which another 3.66 km of theclosing dike had to be added. On average,width at the top was about 50 m.

The temporary division of the inner watersof Port 2000 made by building thistemporary access dike had created separatebasins with a length of 1 to 2 km each.Finally, in order to eliminate the strongcurrents which generate erosion risks, the temporary access dike and the easterndike were opened and closed in oneoperation, thereby sustaining theequilibrium between two huge basins.

DREDGING WORKS

From the beginning several factorsinfluenced the mobilisation schedule of theequipment and in particular the preparationof the dredgers, especially those designated

and an alternative solution was proposed to ameliorate the environmental impact.The phasing proposed in this offer isdescribed as follows. The works would start with dredging theinner basin and creation of the innerbunds. In the first phase this would allow: – only a very limited deviation of the flood

currents, which reach peak values of 5knots (2.5 m per second at high tide).

– and the ability to take advantage of thepresence of gravel in the upper layers,making an immediate construction ofthe eastern bund possible.

After closing the bund, a reclamation areawas made available in which sand could be stocked. The eastern and centralsections of the reclamation cover an area of78 ha and provide a fill of 7.7 million m3.Underneath the dredged sand other gravellayers were situated so that in a second phase

Figure 4. The caissons or “musoirs” being filled and placed at the entrance of the new port.

26 Terra et Aqua | Number 104 | September 2006

to operate in the gravel areas: These includeda very tight schedule, combined with offshoreconditions like huge tides up to 8 m andstrong currents. For these reasons thefollowing dredgers were deployed.

Cutter suction dredgers (CSDs) were chosento dig the internal channel, pumping thegravel through the dynamically positionedand guided diffuser Pontoon Bayard IIdirectly into the sub-base of the futurebunds and breakwaters. Sandy materialswere reclaimed in the areas limited by theinner bunds. Significant investments weremade in dredgers like the Vlaandern XIX,for instance, by introducing wear-resistantlayers in the pipelines and the pump housesbefore starting the works so as to beprepared for gravel dredging.

Trailing hopper suction dredgers (TSHDs) ofdifferent capacities were needed. At first,small and medium dredgers having a limiteddraught were deployed, so as to initiate aminimum channel in the shallow areas.Thereafter high capacity dredgers as Antigoon(8000 m3), Lange Wapper (13,700 m3) andUilenspiegel (13,700 m3), to accelerate the creation of the channel and to importthe gravel from the western area into theunderwater stock areas were introduced.Dipper dredgers such as the Big Boss andZenne were brought in for particular

operations during archaeologicalinvestigations on historic wrecks andassistance with complementary ordnanceclearing operations, as well as thelengthening of the submersible dikesalongside the navigation channel to Rouen.

Pontoons with heavy cranes like De Beverplus an armada of tugs, multicats, floatingand submerged pipelines as well as crewvessels and a survey boat equipped withlatest technologies as multibeam sonarsprovided general assistance (Figure 5).

Table I presents an overview of the mainequipment used. Up to 250 people weremobilised for the operations whichcontinued for three years continuously on a seven days a week, 24 hour a day.

SUB-BASE CONSTRUCTION

The sub-base of the dikes had been designedas a massive construction situated in gravelwith a top level at +3 m CMH, directly placedon the seabed. Therefore the constructionhas a variable height going from 3 m forthe shallowest areas up to 6 m for thedeepest. On the top, it has a 50-m width,with a mean section of 350 m2. With atotal length of 10 km, 3,500,000 m3 wasthus required to be placed.

Taking these quantities into consideration,combined with the offshore circumstances,a major concern for the Joint Venture fromthe beginning was to develop a techniquewhich could manage the quantity ofreclaimed materials as well as expedite theprogress of the works. This demandedbeing able to take advantage of favourableweather conditions whenever possible.

To meet these requirements a techniquewas devised in which the gravel wasdirectly pumped using a CSD as thedredging unit and a dynamically positionedand guided diffuser (DPGD) pontoon asreclaiming unit. The DPGD measures thedensity and the velocity of the materialsdelivered by the CSD, calculates thequantity of materials needed on the spot to realise the sub-base, and automaticallycontrols the winches of the unit. Thesetechniques allowed the work to progress at300 m sub-base per week, compared withprogress of less than 100 m using theclassic dipper and split-barge techniques.

The DPGD Bayard II was designed to work inthe Seine estuary currents of up to 5 knots.

A major concern however remained thestability of the sub-base once realised. A known phenomenon is that at currents of5 knots small gravel tends to start rolling.

Table I. Overview of the main equipment used during the three-year project.

Type Name Installed Power Hold capacity Principal tastCSD Vlaanderen XIX 11,728 kW Dredging of gravel material, pumped directly into the sub-base

through DPGD Bayard II. Reclamation of gravel beachesDPGD Bayard II Gravel sub-base construction

Ballasting caissons after their installationCSD Rubens 10,896 kW Sand dredging and reclamationCSD Vlaanderen XI 9,862 kW Sand dredging and reclamationTHSD Lange Wapper 13,700 m3 Channel dredgingTHSD Uilenspiegel 13,700 m3 Final Channel DredgingTHSD Antigoon 8,400 m3 Dredging and transport of gravel to the under water stock areasTHSD Vlaanderen I 2,065 m3 Minimum channel realisation and accompanying dredging

works in the new flood channelTHSD Vlaanderen XXI 1,751 m3 Accompanying dredging works in the new flood channelTHSD Charlemagne 5,000 m3 Gravel dredging for the realisation of the caisson foundationsDipper Big Boss 1,928 kW Wreckage removal and complementary ammunition removalDipper Zenne 805 kWSplit barge DI 68 1,000 m3

Split Barge DI 69 1,000 m3

Heavy Lifting pontoon Rambiz Installation of the « musoirs »

Port 2000, Le Havre’s New Container Terminal: Breakwaters and Dredging of the Nautical Access Channel 27

As explained in the “phasing” chapterabove, the western part of the sub-basewas planned to remain unprotected forseveral months before construction of theupper dike. Furthermore, the gravel layerspresent in the areas to be dredged containa significant quantity of sand, which is evenmore susceptible to erosion.

Using a partnering concept between client,contractor and the engineering companySogreah, a detailed study programme wasset up to search for a solution. Combiningmathematical and physical models, as well asexperimental try-outs on site, did ultimatelyhelp to adapt execution methods aimed atreducing the erosion of sub-base material.Mathematical modelling was followed byphysical modelling and trials on site.

The solution found was to anticipatepartially the movement the gravel wouldundergo and to adapt the sub-base designin its first phase. It was estimated that300,000 m3 of gravel consumption waseconomised thanks to this adaptation.

VIRGINIE AND STEPHANIE

Two concrete caissons (L x W x H = 55 m x21.5 m x 30 m) were constructed in thedrydock “Forme 7” inside the existingharbour. They weighed 13,000 tonnes eachand represented, after flooding, a draughtof about 13 m. These two caissons markingthe entrance of the new port were namedafter the two site secretaries, Virginie andStephanie, in tribute to their work. To stabilise these floating “matchboxes”posed on their side during transport, theheavy lifting pontoon Rambiz was used. By lifting about 1000 tonnes, it reduced the draught to 12 m.

Utilising pre-installed anchors, the pontooncould be positioned very accuratelyallowing a tolerance of a few centimetres.Taking advantage of the outgoing tide and by ballasting the caissons, the sinkingwas realised in a controlled way. Oncetouch-down took place on the foundationsat –16.50 m CMH, further ballasting wasimmediately executed by pumping gravelthrough the DPGD Bayard II especiallyadapted to this particular situation.

Special attention was paid to theconstruction of the foundations, which alsoused dredged gravel delivered by the graveldredger Charlemagne. Before placing thecaissons, the foundation bed at –16.50 mhad to be levelled with a precision of 5 cm.To meet the demands of this precision, theCSD Vlaanderen XIX was equipped with alevelling plate instead of the standardcutterhead and a tension wire for preciselydouble-checking the exact level of theplate. Good weather conditions prevailedonce again, and allowing use of thistechnique, which proved decisive for thesuccessful completion of construction.

CONCLUSION

There is no doubt that the realisation of aproject like Port 2000 demands the combinedexperience of engineers, superintendents,captains and their crews. On the otherhand, a project like Port 2000 results in broadening the experience of all theparticipants.

Amongst the challenges faced by the JointVenture were the exposure to difficultweather circumstances with heavy seaswells, reckoning with strong tidal andcurrent changes, the safety factors of thepossible presence of military ordnance andlimiting the displacement of large quantitiesof sediment and their deposit in thenavigation channel of the Seine. This latteritem has both economic and ecologicalconsequences.

During the 47 months of work 250 peoplewere continuously on the job and each andevery piece of major plant in the DredgingInternational fleet was occupied. Thus as aneconomic driver, the development of thePort 2000 project was a significant force. In the future as well this role will continue,as the long-term aim of the new Port at Le Havre is to become a logistics hub forcontainer vessels in northern Europe. In thisway, the port of Le Havre will provide thelocal population with sustainable growththat is environmentally acceptable andbeneficial for the development of theregion as a whole.

Figure 5. Several of the dredging vessels

can be seen working simultaneously to

prepare the channel.