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INTERNATIONAL DREDGING AND MARINE EXPERTS

BOSKALIS NORDIC TODAY

BOSKALIS AREA NORDIC | INFORMATION MAGAZINE

NO. 02 / 2014 — 2015

EDITOR-IN-CHIEF Henrik Holmberg

P +358 (0)9 6136 2622

F +358 (0)9 6136 2700

E-MAIL: henrik.holmberg@boskalis.com

BOSKALIS AREA NORDIC

Boskalis Area Nordic has strong experience and special

know-how in harbour and marine construction. Specialisation

in different types of services, such as underwater drilling and

blasting, port construction and various dredging methods in

different soil types, has made us one of the leading contrac-

tors in the Nordic countries.

The Boskalis Area Nordic companies mentioned below

provide all the services in their region.

TERRAMARE OY | FINLAND

BOSKALIS SWEDEN AB | SWEDEN

ROCK FALL COMPANY LTD | UNITED KINGDOM

TERRAMARE EESTI OÜ | ESTONIA

OUR COMMON WEBSITE: WWW.BOSKALIS.FI

IN THIS ISSUE01

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COVER PICTURE

MARIEHOLM TUNNEL, GOTHENBURG

GRAPHIC: TRAFIKVERKET (THE SWEDISH

TRANSPORT ADMINISTRATION), SWEDEN

MANAGING DIRECTOR'S COLUMN

CONSTRUCTION INDUSTRY IS PICKING

UP IN EUROPE.

CUSTOMER NEWS

TRAFIKVERKET'S PROJECT MANAGER STEIN

KLEIVEN.

THE SIX-YEAR LONG MARIEHOLM TUNNEL

CONTRACT

A SIX-LANE HIGHWAY TUNNEL IS BEING BUILT

UNDER THE GOTHIA RIVER, WHICH CUTS

THROUGH THE CITY OF GOTHENBURG.

PALDISKI STRENGTHENS ITS

COMPETITIVENESS

THE FAIRWAY DREDGING OF PALDISKI SOUTH

HARBOUR IN NORTHWEST ESTONIA AND THE

ROCK REVETMENT AT THE FRONT OF THE QUAY.

NEWS

MYSTERIOUS AERIAL BOMB FOUND WHEN

DREDGING THE RIVER TORNIO.

BOSKALIS AREA NORDIC SITES TODAY

BACK COVER PICTURE

BACKHOE DREDGERS WODAN AND

NORDIC GIANT

PAGE 06

PAGE 10

Boskalis Area Nordic´s parent company is the globally

operating Royal Boskalis Westminster N.V. The listed

company operates in 75 countries on six different continents.

NORDIC ECOLABEL 4041 0750

Ecolabelled Printing Paper

Valio's new plant in Riihimäki. For Yara, in Uusikaupunki, we have completed a repair contract for their present quays and built a new tug boat quay. The harbour is now ready to re-ceive vessels of deeper draught. Just before Independence Day, dredging work for the fl ood control of the River Tornio was completed in very challenging conditions. At the handover event, representatives of the cities of Tornio and Haaparanta expressed their warm appreciation to all project participants for the fact that this important joint project between Finland and Sweden, of more than 20 years, was concluded on time and within the original budget. In this project too, our com-pany worked according to clarifi ed operating principles in a concrete way: we do what we promise, right fi rst time and working together.

Forecasting positive prospects for 2015 is in no way easier than it was last year. The prospects of starting new projects, particularly in Finland, are still sluggish, although we do as-sume that the worst is already behind us. In spite of everything, our order book is presently relatively good, about MEUR 48, of which, however, only MEUR 18 is budgeted for next year. It is noteworthy that our order book currently consists of only overseas projects. In any case, we do see a little light at the end of the tunnel, and we strongly believe that the growth in infrastructure investments will gradually start to show, even here in Finland.

Jarmo Yletyinen

MANAGING DIRECTOR, TERRAMARE OY, FINLAND

03

CONSTRUCTION INDUSTRY IS PICKING UP IN EUROPE

The year gone by reached its end leaving behind one of the 'stickiest' years ever in the construction industry here in Finland. In Europe, 2013 was a watershed for the sec-

tor. It was then that seven years of negative growth ended. Ac-cording to a new market review of the Euroconstruct countries, the drivers of future growth will be Eastern European countries with EU project funding as the engine.

Construction is still shrinking in France, Spain, Italy, Portugal, Slovakia and Finland. In a comparison to the Nordic countries, our position is no better as, particularly in terms of infrastruc-ture construction, we remain clearly behind Denmark, Norway and our nearest neighbour, Sweden. The commitment of the Norwegian and Swedish governments to basic infrastructure construction is more sustained than what we are used to here in Finland. The results are visible as an increased maintenance backlog, the scale of which is already approaching such a size that a quick fi x is no longer possible. The working groups of all parties published their results in December, according to which the maintenance backlog now stands at €2.4 billion. The maintenance backlog means the sum of money that is needed to put the state-owned roads, railways and waterways into a condition that meets present needs.

For Terramare, 2014 was a record-low year in Finland, ow-ing to the clear decrease in the volume of marine construc-tion when compared to the previous years. The effect of the Parliamentary elections coming this spring is already palpa-ble, as new fairway projects such as those at Kokkola and Vuosaari need decisions by the future Parliament. Our opera-tions abroad have, however, been active. For this, thanks are due to our nearest neighbour, Sweden, whose busy infrastruc-ture market is employing most of our personnel and equip-ment. Our latest projects in Sweden have been the quay work at Kapellskär and the commencement of the Marieholm Tunnel work in Gothenburg. In addition to these, we have also begun preparatory work in the Elleholm harbour project in Southern Sweden, which will keep our experts employed until spring 2015. Elsewhere abroad, since the end of the year we have been carrying out channel dredging and erosion protection works at Paldiski South Harbour. Backhoe dredger Koura has long been working at Rostock in Germany installing an under-sea cable for the Baltic 2 offshore windfarm. This work will last until spring 2015 and is having a positive impact on our winter employment.

But certainly some things have also been happening in Fin-land. In the second half of 2014, we completed the concrete slipform casting and foundation work for the stairtowers at

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CUSTOMER NEWS | TRAFIKVERKET'S PROJECT MANAGER STEIN KLEIVEN

TOWARDS A SHARED GOAL, BEING PREPARED FOR CHALLENGES‘

‘

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T rafi kverket's Project Manager Stein Kleiven exudes satisfac-tion. The four-year long competitive

bidding and planning work for the Marie-holm highway tunnel to be built under the Gothia River, fl owing through the city of Gothenburg, is already in the past, and construction itself has fi nally begun. Once it is completed in 2020, the tunnel will bring great relief to the daily traffi c of the city.

“People say that the road network that winds through the centre of Gothenburg is like spaghetti. The people of the city have their own name for the red-painted

interchanges - they call them 'red snakes',” laughs Stein Kleiven.

“But seriously speaking, the situation has long been one of concern, because traffi c volumes have long surpassed the capacity of the road network. Congestion is very bad, particularly in the mornings and eve-nings. Also we’re concerned of a situation where, due to an unexpected problem, we might have to close one of our main high-ways, which would lead to a total grid-lock,” says Kleiven.

The six-lane Marieholm Tunnel is being built alongside the E6 motorway tunnel called the Tingstad Tunnel that also goes

under the Gothia River and was opened in 1968.

“The 455-metre long six-lane Tingstad Tunnel was built to accommodate a traffi c volume of 90,000 vehicles per day. This volume was already exceeded in 1980, and today more than 120,000 vehicles force themselves through the tunnel every day. Once open, the new 500-metre long Marieholm Tunnel will offer a new daily route for 55,000 vehicles, bringing a sig-nifi cant relief to our traffi c congestion,” says Kleiven.

Project Manager Stein Kleiven is su-pervising three different contracts in the

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BEHIND STEIN KLEIVEN IS A SATELLITE IMAGE OF GOTHENBURG

showing the spaghetti-like quality of the city’s congested road network. Marieholm

Tunnel, which will be built beneath the Gothia River that cuts through the city, will

offer considerable relief to the local traffi c.

THE BRIDGES OF GOTHENBURG'S INTERCHANGES ARE PAINTED BRICK-RED.

The same shade will also be used for the future tunnel. This idea comes from the

historic brick buildings in Gothenburg's Old Town. On the upper left edge of the

pictured signs is a sign for lanes subject to congestion charging.

01

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project. The contracts include both the tun-nel itself and new road junctions built as two separate contracts on each bank of the Gothia River.

“In the project bidding process, we de-cided on a new type of innovative solu-tion. We told the contractors exactly what we wanted, and asked each one for their own implementation plan. This proved to be a very fruitful method, as we were able to assess several models of solutions. In close co-operation, and also, by utilizing external experts, such as people from the Chalmers University of Technology, we achieved the best possible means of im-plementation. The tunnel will be built us-ing concrete elements cast in-situ. The site has been planned so as not to disrupt our daily river traffi c on the Gothia River,” ex-plains Kleiven.

A solution has also been sought for Gothenburg's traffi c problems through congestion charges. Cameras located at different road junctions take pictures of the number plates of vehicles and, based on this information, the vehicle owners are sent a monthly invoice. The congestion charges vary according to the time of day and the prices are given on illuminated boards at the locations of the cameras.

“Through congestion charging, we aim to encourage motorists to use public trans-port, and the effect of this has been in the region of 10-15%. Congestion charging also naturally has economic signifi cance, as it has been used to fi nance about half of this tunnel project, among other things. In that way, the motorists get a concrete return on their payments,” says Kleiven.

The construction of Marieholm Tunnel will take six years. The enormous project and long construction period do not worry Stein Kleiven who, during his career, has had experience in the roles of both consult-ant and contractor. He can therefore see things from the perspective of all sides.

“Let's say that, at this stage, I can be fully confi dent as the project is in the hands of top experts. Design work is being done in fi ve different countries, and all the contrac-tors are specialists in their own fi eld. We

BOSKALIS AREA NODIC | WWW.BOSKALIS.FI

are focusing on giving all parties a shared goal and compatible working methods. We are also already aware of the chal-lenges of the project, so we can prepare for them in advance,” says Kleiven.

In the Marieholm Tunnel project, visual aspects are also being taken into ac-count.

“Alongside technical matters, we have also thought about the tunnel's visual look and how well it will sit in the milieu of our city. The main colour for the tunnel and the road junction structures will be brick-red. This shade was chosen from the historic brick buildings in Gothenburg's Old Town,

and we are thus creating a link between the old and the new,” says Kleiven.

When asked for his motto, Stein Kleiven thinks for a moment, then gives a motto for the whole project.

“Borrowing from my compatriot, the Norwegian explorer Roald Amundsen, my motto is 'Let us hope for the best and fear the worst.' This is suitable for this project as we are single-mindedly aiming for the best possible outcome, a shared goal, but we are already preparing for unexpected challenges,” summarises Kleiven.

T he Marieholm Tunnel contract com-missioned by Trafi verket has begun. The contract will be carried out in a

consortium in which the main contractors are Boskalis Sweden AB and Züblin Scan-dinavia AB. Boskalis Sweden will carry out its contract in co-operation with Ter-ramare Oy.

Terramare's Site Manager, Juhani Naukkarinen, is motivated by all as-pects of the project. He has solid expe-rience from a similar project, which was carried out 20 years ago under the River

Medway in Kent, England.“This is an interesting and complex

project, which contains many different work stages. Of course something about the scale of this project is indicated by the fact that the contract will last a total of six years. Although some individual matters are still on the drawing board, the main technical features of the contract are al-ready clear,” says Naukkarinen.

“It's a question of a new traffi c route for Gothenburg's busy and congested traffi c, offering a six-lane motorway tunnel with a

06

THE SIX-YEAR LONG MARIEHOLM TUNNEL CONTRACT

THE NEW HIGHWAY TUNNEL IN GOTHENBURG COMMISSIONED BY TRAFIKVERKET

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Gothia River

Tingstad

Marieholmstad

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CONCEPTUAL IMAGE OF THE

MARIEHOLM TUNNEL PROJECT

The six-lane, 500m-long highway

tunnel will go under the Gothia River.

The driving ramp on the north bank.

The driving ramp on the south bank.

The marina on the north bank.

The marina on the south bank.

The railway bridge being built

beside the tunnel.

07

01

length of 500 metres including ramps. It will go under the Gothia River and serve as a connector of the road networks on both sides of the river.”

DEMOLITION WORK AND ENVIRONMENTAL DREDGING IN THE RIVERBANK AREASThe tunnel construction work has already begun with building demolition work in the riverbank areas of the site. This work entails clearing industrial and warehouse buildings, among other things. Alongside the demolition work, environmental dredg-ing of the site area is also beginning, in which contaminated soil is being scraped from the riverbed with an environmental bucket. This soil contains tributyltin and mercury, among other substances. This dredging will ensure that the contami-nated soil does not fl ow downstream in the construction phase. It is estimated that about 25,000 m3 of mass will be removed by the dredging. All dredging areas are protected with an air bubble curtain, in which perforated air tubes will be lowered to the riverbed around the edges of the dredging area. Air that rises to the surface will form an insulating curtain, which will prevent the turbid water from mixing with other surrounding water.

“In the early stages, once the environ-mental dredging and demolition work have been completed, our contract will also include the removal of wooden and concrete piles from the riverbank areas and the dismantling of quays. On the riv-erbed also lie two wrecks, one a barge and the other an older wooden vessel. We will also be removing these,” says Naukkarinen.

DRY DOCKS AND TUNNEL ELEMENTSAfter the removal work, the riverbank sec-tions will be excavated and dry docks will be built there. Züblin will build massive concrete elements for the tunnel in these

0202

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A 20 METRES DEEP AND 35 METRES WIDE CHANNEL

will be dredged on the bed of the Gothia River. About 400,000 m3

of mainly clay-type soil will be removed from the site.

THE TUNNEL WILL BE BUILT OF MASSIVE CONCRETE ELEMENTS,

which will be fl oated into position and submerged into the channel.

The elements, which will be 100 metres long, 30 metres wide and

10 metres high will be installed in position and connected together

using temporary piles and jacks. The connected elements will form

two three-lane highway tunnels.

Once completed, The Marieholm Tunnel will offer a new and effi cient connecting route, which has been designed to cope with 55,000 vehicles per day.

>

BOSKALIS AREA NODIC | WWW.BOSKALIS.FI

THE SIX-YEAR LONG MARIEHOLM TUNNEL CONTRACT08

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SITE MANAGER,

Juhani Naukkarinen (on the left in

the picture) explains the secrets of

the air bubble curtain. The air cur-

rent rising from the perforated pipe

lowered to the bottom will prevent

contaminated water from spread-

ing in the Gothia River during the

construction stage. In the picture,

airfl ow is visible as a line in front of

the harbour basin.

THE SECTION OF THE TUNNEL

project on the south i.e. Mariehol-

mstad bank prior to the demolition

work. Demolition will be done on the

site of the red warehouses.

THE SECTION OF THE TUNNEL

project on the north i.e. Tingstad

bank. In the foreground, Skanska

people on the site of the railway

bridge to be built next to the tunnel

project.

> dry docks. Three actual elements that go under the river will be built. Each will be about 100 metres long, 30 metres wide and 10 metres high. The driving ramps leading to the tunnels will also be built in the dry docks giving the tunnel a total length of 500 metres. The elements will form two three-lane tunnels.

UNDERWATER TUNNEL CHANNEL AND INSTALLATION OF ELEMENTS The completed concrete elements will be fl oated from the dry dock into a channel, dredged by Terramare, about 20 metres deep and 35 metres wide. In the dredg-ing area, the depth of the river is about eight metres.

“The dredging of the tunnel channel is quite a major undertaking, as a total of about 400,000 m3 will be dredged from an area which is quite compact, mainly clay-based soil. Slopes will also be dredged on the edges of the channel. Once the actual dredging is complete, the channel will be cleaned before the ele-ments are installed. The measuring work for the dredging will be carried out using

transport package for Western Sweden, which aims to extensively upgrade road and rail connections.

“Marieholm Tunnel is certainly not Gothenburg's only traffi c-related project. Right next to our site, they are also building a railway bridge over the Gothia River, the purpose of which is to speed up rail freight traffi c to and from the port of Gothenburg. Here there's plenty going on, and I reckon that the tunnel contract, which will last for years, will be a fruitful experience for eve-ryone. In terms of its currents and surface fl uctuations, the Gothia River is calm, and winter ice is not usually a problem here,” says Naukkarinen.

The Terramare Today magazine will fol-low the construction stages of the Marie-holm Tunnel project in its future issues.

09

0707

a Multibeam echo-sounding device.The concrete elements will be installed

in the channel and connected to each other with temporary piles and jacks. Once the elements are in place, sandfl ow will be pumped between them and the riverbed through pipes ready-built into the elements. When connected together, the installed concrete elements will form a structure that will curve down from the riverbanks in the direction that the traffi c will take.

The sandfl ow pumped under the tunnel elements will form the earth foundations for the tunnel. The sides of the tunnel will also be fi lled with sand and rocks. A layer of rocks and gravel 80 cm thick will be put on top of the tunnel, which will protect the structures from propeller slipstream and vessel anchors that might strike it. At the same time, the layer of rock and gravel acts as a counterbalance, supporting the tunnel and keeping it in position,” explains Naukkarinen.

The construction of the tunnel will hardly inconvenience local traffi c. In the river sec-tion, the work stages will be scheduled so that the river traffi c can pass the site with one side always being free.

Once the underwater tunnel section is ready, the driving ramps leading to the tunnel will be built, as well as the new junctions from the highways located on each side of the river.

TWO MARINAS OVER THE RAMPS The contract also includes marinas to be built over the driving ramps.

“Once the actual contract has been com-pleted, we will construct nearly identical marinas over the ramps on the opposite banks of the river. We will dredge har-bour basins three metres deep and build about 300 metres of fully equipped pile-planking- and tubular piled jetties at both marinas,” says Naukkarinen.

Once completed, The Marieholm Tunnel will offer a new and effi cient connecting route, which has been designed to cope with 55,000 vehicles per day. The contract is included in the Swedish government's

07 THE HIGHWAY CONNECTIONS MARKED IN RED

will be joined to the Marieholm Tunnel in two separate contracts. Looking

more closely at the picture, down from the future location of Marieholm Tunnel

you can see the driving ramp of the Tingstad Tunnel, built in 1968, which also

goes under the Gothia River.

BOSKALIS AREA NODIC | WWW.BOSKALIS.FI

10 THE FAIRWAY DREDGING OF PALDISKI SOUTH HARBOUR AND THE UNDERWATER ROCK CLADDING OF THE QUAY

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T he city of Paldiski, which is located in Northwest Esto-nia, has an exceptional history as a port. The Russians established a naval base there in the 18th century. In

1939, based on a treaty between the Soviet Union and Es-tonia, Paldiski became a Soviet city and military base. In the 1960s, the nature of the base was drastically changed. It was then that it became a training centre for Soviet Navy subma-rines and in particular nuclear submarines. Two nuclear reac-tors for submarines were built there for training purposes, and the base became the only one of its kind in the Soviet Union. Paldiski became a closed city, which meant that access to it was forbidden for outsiders and even for those with passes it was strictly controlled. To be safe, the city was surrounded

with a barbed-wire fence. The last Russian naval vessel did not leave the port until 1994, and it was not until 1995 that the base was fi nally handed back to Estonia.

A PROJECT FAVOURED BY CALM WEATHERThe Soviet nuclear reactors and port buildings have long since been demolished. In their place, a modern port centre has grown up. These days, the area is home to two separate har-bours: the privately-owned Paldiski North Harbour and Pald-iski South Harbour owned by the Port of Tallinn. The fairway for Paldiski South Harbour was dredged to a new depth last autumn. In the project implemented by Terramare, a channel about 1.7 km long was dredged to a depth of 14.5 metres

PALDISKI STRENGTHENS ITS COMPETITIVENESS

11

>

01 A FANTASTIC VIEW OF THE BALTIC SEA

opens up from Paldiski South Harbour. The main

cargoes handled by this very busy import and export

harbour located about 45 km west of Tallinn are tim-

ber, veneer, peat, oil products and scrap metal. New

cars and machinery are also imported through the

harbour. Pictured, on the right, trailing suction hopper

dredger Shoreway, which dredged the soft soil from

the fairway.

0303

from 13.5 metres. Through fairway investments, the harbour improved its competitiveness and can now receive vessels with a gross tonnage of 75,000. The contract also included under-water support for the quay with rock revetment.

Over the years, Paldiski South Harbour has become Esto-nia's most important ro-ro harbour. The main cargo that passes through this busy import and export harbour include timber, peat and oil products, as well as scrap metal, which is also sorted and processed at the harbour. An increasing number of new cars and machines are also being imported through the harbour for both local markets and Russia.

For Terramare's Site Manager, Markku Pöyhönen, the harbour's busy and lively sea traffi c made the dredging project

0101

PORTS IN ESTONIA OWNED BY THE PORT OF TALLINN

OLD CITY HARBOUR, TALLINN•

OLD CITY MARINA, TALLINN•

MUUGA HARBOUR•

PALDISKI SOUTH HARBOUR•

PALJASSAARE HARBOUR•

SAAREMAA HARBOUR•

After the dredging project carried out at Paldiski South Harbour, the fairway will be able to accommodate ro-ro vessels and tankers with a gross tonnage of 75,000. Through this investment, the harbour, which is owned by the Port of Tallinn, is aiming for strong growth.

BOSKALIS AREA NODIC | WWW.BOSKALIS.FI

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>

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THE PLOUGH BARGE LANA

played an important role in the dredging of the

fairway at Paldiski. It levelled out the channels dug

by the dredger Shoreway and the high spots left by

the backhoe dredger Attila. Lana was pushed by the

R-Towing tug Jacob.

AT THE BEGINNING OF EACH PROJECT, Terramare

personnel learn about safety issues at the site. Pictured

is the conclusion of a NINA Start-Up safety meeting

for Paldiski. On the left of the picture, Project Manager

Nick Kalle and next to him, Site Manager Markku

Pöyhönen.

PALDISKI SOUTH HARBOUR

is being developed in many ways. In addition to

harbour expansion investments, industrial parks for

companies utilising the harbours are also being built

in the area.

THE FAIRWAY DREDGING OF PALDISKI SOUTH HARBOUR AND THE UNDERWATER ROCK CLADDING OF THE QUAY

eventful and interesting. The scheduling of the dredging, how-ever, was a great success, and the contract was completed ahead of schedule. The dredging contract was started at the beginning of October and completed by the end of Novem-ber.

“The contract was carried out on time and safely and was also blessed with good weather. Strong winds only disrupted the loading part of the dredging work on a couple of days,” says Pöyhönen.

AN UNUSUAL PHENOMENON IN ECHO-SOUNDINGIn a project which otherwise proceeded quickly, however, an unusual phenomenon was encountered that made echo-sound-ing measurements and the collection of data diffi cult. It was not a new phenomenon, as it has been observed previously in exactly the same area.

“In the phenomenon encountered in echo-sounding measure-ments at Paldiski, the fl uctuation in sound speed in the water is unusually irregular. For this reason, multichannel echo-sound-ing using a Multibeam device carried out on the surface could not be done without additional measurements. The device in question collects precise information about the topography on the seabed, but now it was as if variations in sound speed raised the measuring points on the edges of the scanning sea-bed profi le,” says Pöyhönen.

“We encountered the same thing here in 2008. Fluctuations in sound speed are caused by, for example, the salt content of the water, its temperature and the impurities it contains, but

here they are certainly exceptionally variable,” muses Pöy-hönen.

The measurement problem was solved by manually combin-ing the data from the sensor on the seabed that measures sound speed with the data from the Multibeam device. This solution was quite effective but time-consuming. Based on the topographical data received from the seabed, dredging is

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0404BOSKALIS AREA NODIC | WWW.BOSKALIS.FI

“The dredging and rock cladding of the quay were carried out successfully. Our choice of accommodation at the Laulas-maa Spa Hotel was also succesful. It's rare that, between shifts, the workers get to swim and bathe in sauna so comfortably,” says Markku Pöyhönen with satisfaction.

both planned and monitored.The surface area of the fairway to be dredged totalled

450,000 m2 and the dredged mass about 125,000 m3. The soft layers of soil were removed with Boskalis' Shoreway trail-ing suction hopper dredger. The 90-metre dredger in question has 4,500 m3 of loading space and its dredging reach extends to a depth of 30 metres.

“The Shoreway copes well with windy conditions, so it is suitable for even the most challenging locations in terms of weather. The share of soft soil layers in the dredging mass was 105,000 m3. The remaining 20,000 m3 was hard soil, mainly moraine consisting of rocks, sand and clay, which was dredged by the backhoe dredger Attila. Split barges George and Hans transported the mass over a distance of about six nautical miles to the dumping area,” says Pöyhönen.

The dredging was completed with the plough barge Lana, which levelled out the work done by the trailer and backhoe dredger. Lana was pushed by the R-Towing tug Jacob.

QUAY PROTECTION AND SUPPORT WITH ROCK COVERINGAlongside the dredging contract, protection and support of the quay was also carried out. A 100-metre long ditch going in the direction of the quay was dug along the quay's lower edge to a depth of 15.5 metres. The ditch was fi lled with 500 - 1,000 mm rock. Through this fi lling and support, movements of soil caused by powerful propeller slipstream is prevented, which would otherwise weaken the stability of the quay's piling wall. The rock was ordered from a local limestone quarry. A total of 1,500 tonnes of rock was used to fi ll the ditch. Backhoe dredger Attila and split barges George and Hans were used in the digging and fi lling of the ditch.

14

I n early November, Site Manager Reijo Kultalahti got an unexpected phone call from a dredger at 6.35 in the morning. The bucket of dredger Kuokka-Pekka had brought up a large

aerial bomb at the Tornio river delta. The location was about 7 km south of Tornio and Haparanda, in Swedish territorial waters. Work was stopped immediately, and the local authorities were informed of the matter.

“It was a worrying situation from a point of view of both safety and the timetable. Fortunately the bomb was spotted in time. Dur-ing dredging, the bucket was being tilted above the surface to remove excess water from the dredged mass. It was then that the bomb was spotted,” says Reijo Kultalahti.

Because it had been found in Swedish waters, the Haparanda Police began to investigate it. After receiving the information, the Swedish Defence Forces sent a bomb disposal unit from Stock-holm, which set to work immediately. The bomb was determined to be an old 200-kg aerial bomb and it would be the safest to destroy it at the location. After precautionary measures and a lo-cal announcement, the bomb was lowered back to the seabed in the dredger bucket with the assistance of the bomb disposal unit, after which the dredger and cargo vessels were moved to a safe distance about half a kilometre away. Specialist divers from the Swedish Defence Forces set explosives on the bomb and carried out a controlled explosion.

“I must say that the Swedish Defence Forces acted very quickly here as the bomb was destroyed the day after it was found, at

MYSTERIOUS AERIAL BOMB FOUND WHEN DREDGING THE RIVER TORNIO!

nine o'clock in the evening. Soon after that, we were able to start dredging again. Worries that we would lose several days from the operation were unfounded,” says Kultalahti.

The origin of the bomb is still unknown. It was probably a war-time device. It could have been Russian, but in the early stages of the Lapland War the Germans also bombed the port of Röyttä and nearby Finnish vessels close to the place where the bomb was found. The Germans bombed the port area with Stuka bombers. The most unusual explanation for the origin of the bomb was that it was used to try and blow up the ice barriers of the River Tornio in the early 1970s. In any case, pictures of the bomb were sent for further investigation.

“Sure, bombs like this are found in dredging now and again. The largest bomb that I remember myself was found in the fairway at Mäntyluoto in the early 2000s. It was an aerial bomb weighing no less than one tonne. At that time, the local residents were evacu-ated to a distance of at least one kilometre before the bomb was destroyed,” remembers Kultalahti.

The aerial bomb now found in the River Tornio was raised from the seabed in borderland fl ood protection dredging, in which Ter-ramare Oy was widening and deepening a shallow channel in the delta area over a distance of 6.3 km. The purpose of such dredg-ing is to prevent a risk of fl ooding caused by ice barriers forming in the area.

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BOSKALIS AREA NORDIC SITES TODAY

Olli Väätäjä

Markku Sollo

Christian Gamerdinger

Reijo Kultalahti

Juhani Naukkarinen

Nick Kalle

Pertti Sukanen

PORT RENOVATION, ELLEHOLM, SWEDEN

QUAY REPAIR, YARA, UUSIKAUPUNKI, FINLAND *)

PORT EXPANSION, STAGE 2, KAPELLSKÄR, SWEDEN

DREDGING OF THE MOUTH OF THE RIVER TORNIO, FINLAND *)

MARIEHOLM TUNNEL, GOTHENBURG, SWEDEN

DREDGING OF PALDISKI HARBOUR, PALDISKI, ESTONIA *)

SLIP CASTING RU, 9A, VALIO, RIIHIMÄKI, FINLAND *)

Seppo Ajanko

Seppo Ajanko

Marko Saarelma

Jouko Sederholm

Jouko Sederholm

Jouko Sederholm

Esa Kunnassaari

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Michael Törnqvist, Regional Manager, Boskalis Sweden AB

Timo Soikkeli, Plant Manager, Terramare Oy

Colin Fergusson, General Manager, Rock Fall Company Ltd

Tapio Leinonen, Financial Manager, Terramare Oy

Jarmo Yletyinen, General Manager, Terramare Oy

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