Dr. Luigi Alcaro

DEEPP PROJECTDEvelopment of European guidelines for Potentially

Polluting shipwrecks

D.G. Environment, Civil Protection UnitContract n° 07.030900/2004/395842/SUB/A5

EUROPEAN GUIDELINES ON DATA COLLECTION, ASSESSMENT AND INTERVENTION ON

POTENTIALLY POLLUTING SHIPWRECKS

PROPOSAL

September 2007

Participant Institutions

ICRAMIstituto Centrale per la Ricerca scientifica e tecnologica Applicata al Mare

Via di Casalotti 300 - 00166 Rome, Italy

Principal investigator: Dr. Ezio Amato tel.•: +39.06.61570455 • fax: +39.06.61560196 e-mail: [email protected]

CEDRECentre de documentation de recherché et d’expérimentations sur les pollutions accidentelles des eaux

715 rue Alain Colas - CS 41836 - 29218 Brest Cedex 2, France

Principal investigator: Dr. Fanch Cabioch tél.: 33 (0)2 98 33 10 10 - Fax: 33 (0)2 98 44 91 3

Authors: Luigi Alcaro, Ezio Amato, Fanc’h Cabioch, Cristina Farchi, Vincent Gouriou

INDEX

1 INTRODUCTION........................................................................................................................4

2 OBJECTIVES.............................................................................................................................7

3 REALISATION OF A DATABASE RELATED TO PPSWS.........................................................8

3.1 INFORMATION SOURCES ........................................................................................................83.2 INFORMATION CATEGORIES AND DATABASE STRUCTURE ...........................................................93.3 MANAGEMENT OF THE MAIN RESULTS AND CARTOGRAPHY .....................................................15

4 ENVIRONMENTAL RISK ASSESSMENT OF POTENTIALLY POLLUTING WRECKS............17

4.1 A POSSIBLE RISK ASSESSMENT APPROACH ..........................................................................174.1.1 Determination of Pollutant Volume Classes..................................................................174.1.2 Determination of the Distance from the Coast or a Sensitive Area Classes ...................184.1.3 Nature of Floating Pollutant ..........................................................................................194.1.4 Exacerbation of the Risk Factor: the Age of Wrecks .....................................................204.1.5 Calculation of the Risk Factor (RF) for Floating Chemicals ...........................................204.1.6 Definition of the Scale of Risk.......................................................................................214.1.7 Liquid Sustances Other Than Floating..........................................................................234.1.8 Conclusions .................................................................................................................27

5 THE BEST AVAILABLE TECHNOLOGIES TO MINIMIZE THE ENVIRONMENTAL RISKS.....28

5.1 RECOVERY OF THE ENTIRE WRECK .......................................................................................295.2 SEALING THE LEAKING POINTS.............................................................................................345.3 CONTROLLED RELEASE OF POLLUTANTS...............................................................................355.4 PUMPING OF POLLUTANTS ...................................................................................................365.5 CAPPING OF THE ENTIRE WRECK OR OF THE CARGO ..............................................................425.6 WRECK MONITORING AND INSPECTION .................................................................................46

5.6.1 Wreck inspection..........................................................................................................475.6.2 On-site measurements and wreck monitoring...............................................................48

5.7 FACTORS INFLUENCING THE CHOICE OF INTERVENTIONS TO MINIMISE THE ENVIRONMENTAL RISKS OF PPSWS ....................................................................................................................................52

REFERENCES .................................................................................................................................54

THE PRESENT REPORT INCLUDES A CD-ROM CONTAINING THE “WRECK DATABASE FOR THE PELAGOSSANCTUARY”

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1 IntroductionIn general, a shipwreck is a long-lasting source of pollution because the vast array of marine pollutants utilised for its construction and operation. When a vessel wreckage occurs, very often pollutants are immediately released into the environment and later the shipwreck itself acts as a persistent source of pollutants. In many cases accounted worldwide, furthermore bunker oils and cargo residues “surface” years later when the corrosive processes the tanks are subject to open a way towards. To this respect, shipwrecks may represent a serious hazard for the marine environment.

In the recent years the approach towards this latent form of pollution has undergone a radical change as it has become clear the need to prevent the eventual release of pollutants rather than only responding to it, taking action only when the oil or other hazardous and noxious substances are effectively leaking1.

Only few studies have been carried out until today with the aim of estimating the number of potentially polluting shipwrecks which could represent worldwide a major threat to the marine environment and many efforts have been spent to estimate the amount of oil likely remaining on each vessel. A particular mention deserves a study conducted by the International Oil Spill Conference (IOSC)2. The study written by an international expert group is aimed to realise a database regarding the worldwide distribution of potentially polluting wrecks as well as to classify them on the base of their environmental risk.

The resulting database includes 8,569 potentially polluting wrecks, sunk in the period 1890-2004, with 1,583 tank vessels and 6,986 non-tank vessels. The database focuses only on non-tank vessels with a Gross Tonnage (GT) of at least 400 and tankers with a GT of at least 150.

1 Basta D.J. and D.M.Kennedy, 2004. The need for a proactive approach to underwater threats, Marine Technology Society Journal, Vol. 38 (3): 9-112 Michel J., Gilbert T., Etkin D.S., Urban R.. 2005. Potentially Polluting Wrecks in Marine Waters. An issue paper prepared for the 2005 International Oil Spill Conference (IOSC). 84 pp.. http://www.iosc.org/docs/IOSC_Issue_2005.pdf

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Fig. 1-1: Approximate distribution of potentially polluting shipwrecks (source: http://www.iosc.org/docs/IOSC_Issue_2005.pdf)

The data collected highlight a diffuse presence of shipwrecks in all the world’s seas identifying the South Asian-Pacific region as the area with the highest number of sunken potentially polluting tank vessels, followed by the Northwest Pacific where most of the wreckages date back to the second World War. There is a general concern for WWII vessels as these, representing the largest group of potentially polluting shipwrecks, are approaching the age where further corrosion could increase the possibility of oil leakage.

Fig. 1-2: wrecks distribution in relation of the sunken period(source: http://www.iosc.org/docs/IOSC_Issue_2005.pdf)

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Most probably the recent incidents which caused the loss of vessels, such as the M/T PRESTIGE, the M/T ERIKA and the M/T IEVOLI SUN, as well as a number of vessels that sank decades ago but have started to release oil in the past few years (SS JACOB LUCKENBACH, USS MISSISSINEWA, etc.) have increased the awareness of governments on the necessity to minimise the risk posed by submerged wrecks and/or to remove all pollutants from them. At the same time, the administrators and the scientists feel the need to dispose of methods and criteria suitable to collect appropriate data on potentially polluting shipwrecks and to rank the environmental risk they pose in order to classify them and prioritise the interventions.

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2 ObjectivesIn order to tackle the problems posed by the Potentially Polluting Shipwrecks (PPSWs) and to contribute to the development of a common approach to remediate and/or to minimize the environmental threat they pose within the European maritime countries, the DEEPP (DEvelopment of European Guidelines for Potentially Polluting Shipwrecks) project was co-financed by the Civil Protection Unit of the European Commission and performed by ICRAM (Istituto Centrale per la Ricerca scientifica e tecnologica Applicata al Mare) and CEDRE (CEntre de Documentation, de Recherche et d’Experimentations sur les pollutions accidentelles des eaux).

The main objective of the project is to provide European coastal States and National Administrations with guidelines and criteria to face the environmental threats which might arise from potentially polluting shipwrecks. In particular the target-groups concerned are:

• Officers from Ministries, Agencies and/or local authorities with responsibilities on marine pollution issues.

• European scientists and experts on different aspects of marine environmental damage.

• NGOs, other organizations (possible interested sectors: fisheries, environment, tourism, oil industry, shipping).

These Guidelines are a proposal for an European-coordinate effort to increase the level of preparedness to minimise the impact deriving from PPSWs sunk in European seas. This report want to be a first proposal of European Guidelines for Potentially Polluting Shipwrecksthat need to be argued within representatives of all the European Countries to dispose of a common and shared document.

These proposed European Guidelines could be considered a synthesis of all the DE.E.P.P.project that has been divided in two separate phases. The first phase has been dedicated to the development of the pilot project Database for Potentially Polluting Wrecks within the Mediterranean Cetacean Sanctuary aimed at both establishing methods and procedures suitable to collect data on potentially dangerous wrecks and identifying the most dangerous shipwrecks within the investigated area

The second phase has been dedicated to a comprehensive workshop (Potentially Polluting Wrecks: Technical, Legal and Financial Perspectives) where international experts have debated on technical, legal and financial aspects which need to be evaluated by the competent organizations when considering the possibility for clean up operations.

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3 Realisation of a Database Related to PPSWs

3 Realisation of a Database Related to PPSWsThe use of an uniform criteria for data collection is a nodal point. The standardization of database is mandatory to allow the accessibility and comparability to all the stakeholders. A common protocol is very useful both to exchange information and to integrate data. It means: a common classification of inventoried wrecks; establishment of indicators and data to be collected; prioritize them.

The collection of data probably will shows some missing information particularly related to the cargo characteristics and name of wreck.

3.1 Information sources

The information to insert in a database come from various different sources. The operators have to be very careful while inserting the data in order to avoid any duplication of records. A huge effort is made to combine the available information and to produce the most comprehensive and reliable data sets especially in case of conflicting information arising from the different sources.

The main steps to carried out are listed below:

ü IDENTIFICATION OF WRECKS

A close collaboration could be established with the Navy Hydrographic Institutes which usually provide most of the wreck data, with particular reference to the geographic position of wrecks mainly achieved through electroacoustical surveys as well as their dimensional data. In fact, the aim of these Institutes is to collect information mostly with the aim of gathering information related to the aid to navigation.

Further information could be acquired from private agencies that produce detailed databases of main wrecks sunk in specific area (e.g. Mediterranean basin), often available on the website.

Other additional information could be gathered from the Coast Guard. In particular the peripherical offices give additional information on wrecks located within their area of jurisdiction.

Moreover, specific books on shipwrecks could be consulted, some reported in the bibliography hereinafter. Finally, the Geographic Information System (GIS) may to be used to complete the database with lacking data and in particular inserting the distance from the coast knowing the geographic coordinates and, at the contrary, adding the geographic coordinates if the distance and direction from a specific location is known.

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ü ACQUISITION OF WRECK TECHNICAL DATA

After the identification of shipwreck’s names, some detailed information may be collected consulting the Lloyd’s Register books where the main characteristics of vessels are indicated as: length, width, gross tonnage, engine power, bunker tanker volume, bunker type, etc.

ü ACQUISITION OF SOME MORE INFORMATION

Finally, the consulting of dedicated websites, such as diving centres and on line databases allows to gather more information with particular emphasis on both historical pictures of vessels or photos of wreck and description of sinking.

ü FINAL VERIFICATION

With particular reference to the most dangerous wrecks selected, the data obtained have to be verified directly through interview to stakeholders which have in some way observed the wreck, like fishermen or divers.

3.2 Information categories and database structure

A particular attention has to be dedicated to the categorisation of data acquired, which gives a valid contribute to the elaboration of risk assessment. A total of 50 categories are chosen taking into account both technical characteristics of the wreck and the properties of its cargo when known. Environmental information regarding the location of wreckage is also added. However, various wrecks within the database will show some missing information and the major lack of data regards specifically their cargo.

The main categories to be inserted within the database are shown and described here below:

NAME

TYPE OF WRECK. The wrecks are divided on the basis of predefined categories (oil tanker, bulk carrier, ferry, military ship, trawler, other)

DESCRIPTION OF WRECK. All information not included in other categories like detail of wreckage, specific characteristic of ship, previous names, etc.

CAUSE OF SHIPWRECK. The cause of shipwreck has been categorised following the standardisation already used in REMPEC database4: collision (contact between two ships); contact (contact between a ship and another object); engine breakdown (breakdown or malfunctioning of ship’s main engine); fire/explosion (fire and/or explosion on board a ship); bad weather conditions; grounding; hull structural failure (accident caused by structural failure of a ship’s hull).

SHIPWRECK DATE. Both the full date and year of shipwreck are indicated.

GROSS TONNAGE (ton), LENGTH (m), WIDTH (m)

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FLAG STATE, BUILDING DATE, SHIPYARD

TERRITORIAL WATER

LOCATION. Indicates the name and distance from the nearest point on land, cape, bay, etc.

LONGITUDE AND LATITUDE. Geographical coordinates based on a specific geodetic system (WGS 1984, ED 50, etc.).

LOCALISATION ACCURACY. This information has been categorised as follows: certain (localisation accuracy between 0 and 10 meters); medium (localisation accuracy between 10 and 500 meters); poor (more than 500 meters); very approximate when only the general location is known (e.i. Genoa gulf).

DISTANCE FROM COAST AND FROM SENSITIVE AREA. The distances from coast and/or from sensitive area, useful for risk evaluation, have been divided in the following ranges: from 0 to one nautical mile; from one to 10 nautical miles; from 10 to 50 nautical miles; more than 50 nautical miles.

DEPTH, NATURE OF SEABOTTOM. The nature of sea bottom is categorised as follows: mud, sand, rock, posidonia meadow; gravel.

BUNKER NATURE AND BUNKER VOLUME. Two categories of hydrocarbons have been used: diesel oil and heavy fuel oil. In a few cases the bunker utilised is coal. On the database the symbol “*” could be added to the Bunker Nature whenever the class product was deducted from the gross tonnage: generally, “Heavy/Medium crude oils HFO/IFO” when the gross tonnage is upper than 3.500 GWT, and “Diesel-Fuel-Kerosene” when the gross tonnage is lower than 3.500 GWT. This rough correspondence has been observed reading the data available on Lloyd’s Register books.

BUNKER VOLUME. Due to the scarce information on bunker volume value, often a rough estimate of it has been made knowing the dimensional data of ship (e.g. gross tonnage). In fact a direct proportion between the two values has been demonstrated comparing, also in this case, the data available on Lloyd’s Register books as shown in fig. 8-3.

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Fig. 3-1: Gross tonnage (ton) vs bunker volume (m3) using data reported in Lloyd’s Register books

The bunker volume value has then divided in five separate classes as follows:

Bunker Volume (m3) Gross Tonnage (ton)

<100 0-500

100 - 500 500 – 3.500

500 – 2.500 3.500 – 25.000

> 2.500 > 25.000

BUNKER VOLUME REMAINING (HIGH ESTIMATE). As for the bunker volume, a rough estimate of bunker oil remaining onboard the wreck has been made. The methodology for estimation used is the same already applied in the IOSC publication5. A high estimate is calculated assuming that a tank vessel had at least 70 percent of its bunker capacity.

BUNKER VOLUME REMAINING (LOW ESTIMATE). Like the high estimate evaluation, also in this case the IOSC publication has been taken into account59. A low estimate was calculated based on the assumption that half of the vessels would have been 80 percent full and half would have been 20 percent full at the time of sinking and that an estimated 80 percent of the oil would have been either spilled at the time of the sinking or seeped out in the following

5 Michel J., Gilbert T., Etkin D.S., Urban R.. 2005. Potentially Polluting Wrecks in Marine Waters. An issue paper prepared for the 2005 International Oil Spill Conference (IOSC). 84 pp.. http://www.iosc.org/docs/IOSC_Issue_2005.pdf

y = 0.1164x + 126.88R2 = 0.5479

0

200

400

600

800

1000

1200

1400

1600

0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000

Gross_tonnage

Bunk

er_v

olum

e

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years. The average would then be 10 percent of the total potential amount of oil still left as shown in fig. 8-4.

Fig. 3-2: Low bunker oil estimate methodology

POWER ENGINE. This value indicates in several kinds of horsepower: nominal horsepower (nhp); indicated horsepower (ihp); brake horsepower (bhp).

CAPACITY OF HOLDS.

CARGO NATURE AND CARGO CLASS. The cargo class is referred to the new MARPOL classification of liquid pollutants: class “X” (Noxious Liquid Substances which are deemed to present a major hazard to either marine resources or human health); class “Y” (Noxious Liquid Substances which are deemed to present a hazard to either marine resources or human health or cause harm to amenities or other legitimate uses of the sea), class “Z”(Noxious Liquid Substances which are deemed to present a minor hazard to either marine resources or human health); class “OS” (substances which have been evaluated and found to fall outside Category X, Y or Z because they are considered to present no harm to marine resources, human health, amenities or other legitimate uses of the sea)

RISK DESCRIPTION. Risk value given on the basis of several risk factors which were taken into account (distance from coast, pollutants volume, pollutants type) (see chap. 10). The risk value is categorised as follows: serious, moderate to serious, moderate, minor to moderate, minor and undetermined.

Exacerbating Factor: In the database each identified wreck will be affected by a weight as defined in the following table 3-1:

Exacerbating Factor Wreckage Year

* wreckage year < 20 years

** 20 years <wreckage year < 40 years

*** 40 years <wreckage year < 60 years

**** wreckage year > 60 years

It represents an alternative way to indicate the importance of marine corrosion on a specific wreck: its effects are more evident in older wrecks.

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SPILL DESCRIPTION. Indicates the type of pollutant actually spilled or released during the accident as well as the actions taken during the emergency phase.

WRECK STATUS OF CONSERVATION. The wreck status of conservation is indicated (entire, divided in two parts, partially covered by sand; lying on the left side, etc.)

DIFFUSION WRIGHT. The diffusion wrights have been categorised as follows: free, reserved diffusion, restricted diffusion, confidential.

DATA SOURCE.

Particular attention has to be given to the structure of the database in order to make it as more user friendly as possible. Four different pages appear to the users with all relevant information related to a single wreck (fig. 4-3). Moreover a wreck summary appears in an A4 format. A Cd-Rom containing the “Wreck Database for the Pelagos Sanctuary” produced during the first part of the DE.E.P.P. project is included.

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Fig. 3-3: Graphic user interface of the database realised within the DE.E.P.P. project

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3.3 Management of the Main Results and Cartography

With the aim to compare the results achieved in European seas by different Institutions, we suggest to manage them in an uniform way. With this in mind, the wrecks selected could be classified on the base of their:

− distance from coast ;

− depth;

− typology;

− gross tonnage;

− bunker oil content (high and low estimate)

− cargo content

− wreckage year

The value classes to take into account for each category are those indicated in the previous paragraph. The results must to be shown through graphics and tables as well as producing thematic cartography using a Geographic Information System (GIS) useful to manage many different kinds of georeferenced information, processing it into compatible datasets,combining it, querying it and analysing it.

Consequently, a series of maps could be produced:

− DISTRIBUTION OF ALL SHIPWRECKS SELECTED ;

− DISTRIBUTION OF SHIPWRECKS SELECTED ACCORDING TO TYPOLOGY AND DIMENSION;

− DISTRIBUTION OF SHIPWRECKS SELECTED ACCORDING TO YEAR OF WRECKAGE;

− DISTRIBUTION OF SHIPWRECKS SELECTED ACCORDING TO BUNKER OIL CONTENT.

− DISTRIBUTION OF THE MOST DANGEROUS SHIPWRECKS SELECTED.

An example of cartography produced with the DE.E.P.P. project are reported in figure 4-12.

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Fig. 3-4: Distribution of all shipwrecks selected in the pilot area

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4 Environmental Risk Assessment of Potentially PollutingWrecks

The seriousness of a spill does not depend only on the volume of oil or other HNS spilt during an incident. Other factors, such as location of incident, behaviour of the oil or other pollutants, prevailing meteomarine conditions and sensitivities of the environmental resources may result even more important. Therefore it is essential to undertake a careful assessment of both the areas under threat and the resources at risk in order to better understand the possible consequences of a spill event6.

4.1 A Possible Risk Assessment Approach

Since Cedre and ICRAM have been confronted to old and recent shipwrecks (also called relic and contemporary shipwrecks, respectively), one of the first concerns for the authorities is to assess the risk posed by a wreck for human activities and environment. The parameters to be taken into account by the advisers and scientists acting in this field of competency have been listed in the database structure (see paragraph 4.2).

The methodology we propose takes only a few parameters into consideration:

− Pollutant Volume

− Distance to a coast or a sensitive area when available

− Nature of the product involved: fuel or cargo

− Exacerbating factor: age of the wreck

4.1.1 Determination of Pollutant Volume Classes

As already mentioned in chapter 4, four classes of pollutant volume have been taken into account following the fuel volume estimation (fuel tanks 100% full).

6 SPREP, 2002. A regional strategy to address marine pollution from World War II wrecks (Endorsed at 13th

SPREP Meeting, Majuro, Marshall Islands, July 2002 - approval given to implement Steps 1-3). www.sprep.org

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Tab. 4-1: determination of the pollutant volume classes

Class of Volume Pollutant Volume (m3) Comments

1 <100Fuels (vessels up to 500 GWT)

− Lost Containers

− Small coastal tankers

2 100 - 500

Fuels (vessels ranging from 500 to 3.500GWT)

− Small chemical tankers, Barges

− Coastal oil tankers

− Container ships

3 500 – 2.500

Fuels (vessels ranging from 3.500 to 25.000GWT)

− Coastal oil tankers

− Barges

− Chemical tankers

− Container ships

4 > 2.500Fuels (vessels over 25000 GWT)

− Chemical tankers

− Oil tankers

The determination of the class limits is something subject to discussion. The amounts that have been taken are based on the fuel volume and the volume of cargo tanks generally met on chemical tankers, depending on their classification (type 1, 2, or 3). However, these limits can be considered as a rule of thumb.

As far as container ships are concerned, the volume is considered as a total volume of dangerous goods, taking into account that about 10 to 15 % of the tonnage transported is considered as dangerous. The volume of a specific given chemical in a container ship is barely above 200 m3, which represent about 10 tank containers (20 m3 each).

4.1.2 Determination of the Distance from the Coast or a Sensitive Area Classes

The parameters taken into consideration are coming from the surface drift speed. A windspeed between 5 to 10 knots has been chosen.

The classes of distance are taken into consideration considering that:

− In a few hours with wind blowing to the coast, a floating pollutant will reach the coast if the spill happens a few mile far.

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− In one day, without the tide current effects or any general current influence, the distance covered by a floating slick range from 4 miles to 10 miles.

− In a few days, the distance will range from 10 to 50 miles.

− The distance covered by a floating slick during one to a few weeks will be more than 50 miles.

Following this reasoning process, we have taken 4 classes of distance shown in the table below.

Tab. 4-2: Determination of the class of distance

Class of Distance Distance from the coast

1 D<1 mile

2 1 mile<D<10 miles

3 10 miles<D<50 miles

4 D>50 miles

4.1.3 Nature of Floating Pollutant

This class has been considered in the Risk Assessment Matrix applied to evaluate the risk level of a shipwreck (par. 5.1.6). Two kinds of floating pollutants have been considered: hydrocarbons and liquid chemicals.

For the hydrocarbons, fuel oil or cargo, persistency is the main risk parameter. The more persistent the oil is, the most hazardous it is.

The light fractions (up to C10) will evaporate within a few hours. That is the case for petrol and for the lighter component of heavier fuel.

Diesel oils and equivalent products (C9 to C20) will evaporate up to 30%-40 % within a few days while the heavier fractions will disperse naturally in the environment due to the low viscosity of these products categories.

Intermediate fuel oils (IFO 180 and 380 now called ISO RME180 and 380) and heavy fuel oils (HFO 700 also called now ISO RMK 700) will evaporate at a few per cent and will remain on the sea surface for a long time (months for the heaviest ones). These products will also emulsify up to 60% after a few days at the sea surface. They are persistent products likely to impact the shore lines for a long period of time after being released at sea.

As far as crude oils are concerned, we have divided them in light crude and heavy/medium crude. The first ones represent an intermediate class between Diesel oils and IFO/HFO, the second are inserted in the IFO/HFO class. Light crude oils will evaporate at about 50% of the initial volume, the remaining will naturally disperse and emulsify.

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Liquid pollutants carried in bulk are categorised in 4 classes by Marpol: X,Y,Z and other substances (O.S) The Marpol X substances are likely to produce the most severe impact on man and environment (see chapter 4) and are very stable and liable to bioaccumulate in the food web.

4.1.4 Exacerbation of the Risk Factor: the Age of Wrecks

The corrosion is a relatively slow process that weakens the metal. Small holes in the hull induce the coming out of small droplets of pollutant. The precise flowrate is difficult to appreciate; experience shows that it ranges from less than a litre/hour to a few l/h.

On the other hand, the hull is fragilised by corrosion and we have seen that a fisherman trawler may affect the hull until inducing a leak (see figure 5-1). In this case the output flow rate could reach 1m3/h.

Fig. 4-1: Picture taken in April 2007 in the gulf of Biscay at 118 m depth, showing a hull of an old unidentified shipwreck broken by a trawling net cable. We can see the traces of the cables (trawl warps) where the barnacles are disappeared. (source: French Navy)

In our database we affect each identified wreck by a weight that represent the ExacerbatingFactor (see par. 4.2)

4.1.5 Calculation of the Risk Factor (RF) for Floating Chemicals

The determination of the risk factor is based on the quotient Class of volume/Class of distance

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According to this definition, we will get 11 different risk factors.

RF=Class of volumeClass of distance

Tab. 4-3: Calculation of the Risk Factors (RF)

Class of Distance FR

1 1

2 1/2

3 1/3Volume Class 1

4 1/4

1 2

2 1

3 2/3Volume Class 2

4 1/2

1 3

2 3/2

3 1Volume Class 3

4 3/4

1 4

2 2

3 4/3Volume Class 4

4 1

The Hasrep project7 has taken into consideration another way to calculate the risk factor for the transport of dangerous goods by sea.

4.1.6 Definition of the Scale of Risk

As for the planning of response operations in case of oil spill, which is divided in 3 Tiers (http://www.ipieca.org), we have chosen three main levels of hazard based on potential impacts determined by an eventual release of pollutants from a wreck.

The impact levels are the following

7 HASREP project “Response to harmful substances spilled at sea”, WP4, Project co-funded by the European Commission under the community framework for cooperation in the field of accidental or deliberate marine pollution, http://ec.europa.eu/environment/civil/marin/mp05_en_projects.htm

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• Minor

• Moderate

• Serious

In order to take the class limits into consideration, we propose to add two more intermediate classes:

• Minor to moderate

• Moderate to serious

Serious means that potentially very severe effects are expected. These top priority cases should receive immediate action plan and mitigation.

Moderate represents wrecks that may have impacts. A special care and monitoring should be performed before taking a decision: neutralisation of the risk or leave the wreck as it is, taking into account the accessibility of the pollutants (depth, position of the wreck at the sea bottom, location of the wreck, sea conditions, etc.).

Minor corresponds to wrecks with a limited damage-potential due to the non polluting category of the pollutant or the low Risk Factor. Authorities would prefer to compare cost-effectiveness ratio with other social priorities.

The Intermediate group of risk (“minor to moderate” and “moderate to serious”) must take into account the extreme values of the classes. For example, a risk factor of 1 may correspond to 4 scenarios: 1/1, 2/2, 3/3, 4/4. If we consider the scenario 3/3 it means volumes ranging from 1.000 to 2.500m3 of pollutant, associated with a distance between 20 and 50 miles. The response is not the same if we have 2.400 m3 of pollutant at 21 miles from a coast compared to 1.000 tons at 49 miles from the coast. Each case must be discussed byexperts.

The Risk Assessment Matrix (see fig. 5-2) is useful to give a scale of risk, taking into consideration both the Risk Factors and the nature of the floating pollutant.

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Fig. 4-2: Risk assessment matrix for floating pollutants

4.1.7 Liquid Sustances Other Than Floating

Generally speaking, the impacts presented by the pollutants are a consequence of their behaviour. The Standard European Behaviour Classification system (SEBC)8 proposes an interesting way to rank the chemicals according to their behaviour: Sinkers(S), Dissolvers(D), Floaters (F) and Evaporators (E). Several factors affect the behaviour and the fate in marine environment of a specific pollutant (Fig. 5-3 and Fig. 5-4)

8 SEBC. 1991. Standard European Behaviour Classification (SEBC) System, Bonn Agreement, Counter Pollution Manual, vol. 2, Chapter 25, pp 1-8.

Risk FactorF

4 serious serious serious serious



3/2 serious serious serious serious

4/3 Moderate to serious serious serious serious

1 Moderate to serious Moderate to serious serious serious

3/4 moderate moderate serious serious

2/3 moderate moderate Moderate to serious serious

1/2 Minor to moderate moderate Moderate to serious Moderate to serious

1/3 minor Minor to moderate moderate Moderate to serious

1/4 minor minor Minor to moderate moderate

Hydrocarbons: fuels and cargo

Gasoline Fuel Oil DieselKérosene

Light crude oils Heavy/Medium crude oils

HFO/IFO

Liquid Chemical transported in

bulkMarpol

Classification

OS Z Y X

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Fig. 4-3: Factors to be considered for the study of the behaviour and fate of a chemical substance in marine waters (SEBC, 1991)

PPhhyyssiiccoo--cchheemmiiccaallcchhaarraacctteerriissttiiccss

BBeehhaavviioouurr ooff tthheeCChheemmiiccaall SSuubbssttaannccee

SSEEBBCC

1) Density

3) Solubility

2) Vapour pressure

Floatability

Evaporation

Solubilisation

t0

Air

SurfaceWatercolumnSea floor

A%

B%C%

D%

A’

B’C’

D’

Air

SurfaceWatercolumnSea floor

4) Viscosity

5) Persistence

Emulsion

BiodegradationPhoto oxidationHydrolyse

t0+∆t

Climatic & Oceanic conditions t0+∆t

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Fig. 4-4: Main types of behaviour that can be distinguished for chemicals released into the marine environment as substances, or as packages. Flow diagram. (Source: Bonn Agreement 1999 & 20009 and HELCOM 200210)

The pollutant behaviour determines the compartments of the food web affected (fig. 10-5).

9 Bonn Agreement. 1999. Agenda item 3; Agreement for cooperation in dealing with pollution of the North Sea by oil and other harmful substances, 1983. Eleventh meeting of the contracting parties. Bres. 29 September – 1 October 1999. BONN 99/3/6-E (L).Bonn Agreement. 2000. Bonn Agreement Counter Pollution Manual. Vol. 2, Chapter 25: European classification system 10 HELCOM 2002. HELCOM Manual on Co-operation in Response to Marine Pollution within the framework of the Convention on the Protection of the Marine Environment of the Baltic Sea Area. Volume 2 Response to accidents at sea involving spills of hazardous substances and loss of packaged dangerous goods. Helsinki Convention, 1974.

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Fig. 4-5: Marine life by compartments influenced by several pollutant behaviour11

In order to perform a Risk Assessment of the shipwrecks carrying pollutants other than floating substances as cargo, we have chosen to consider the quotient PEC/PNEC. If the value is greater than 1 it means that a risk exists and it could be serious.

PEC value (Predicted Environment Concentration) is given by models or by in situ measurements. Models give by means of different scenarios (various outlet flowrates) the predicted concentration in the environment. The calculation takes into consideration the volume of water per time unit (depending on the depth and the currents in the water column), compared with the pollutant flow during the same time. It gives a concentration (peak or mean) in the water column or at a given depth, at a given time.

The PNEC value (Predicted No Effect Concentration) for a given species, is given by the literature and generally available in the models databases.

The Technical Guidance Document (TGD) Nr 82, issued by the European Centre for Ecotoxicology and Toxicology Of Chemicals (ECETOC) explains the methodologies available

11 HASREP project “Response to harmful substances spilled at sea”, WP4, Project co-funded by the European Commission under the community framework for cooperation in the field of accidental or deliberate marine pollution, http://ec.europa.eu/environment/civil/marin/mp05_en_projects.htm

Air

(evaporators)

Surface

(floaters)

Water

Column

(dissolvers)

Sea floor

(sinkers)

MammalsPlankton

Birds

Pelagos fish

Sea shore

Benthos

Communities

&

Demersal fish

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to evaluate the PNEC in various compartments of the food web, both on the sea floor and in the water column12.

4.1.8 Conclusions

The risk associated to a shipwreck depends on various factors. Among these, the ones we have taken into account are the most obvious. Nevertheless, many parameters are not technical, such as public pressure and political interest which are out of our scope. Some products are not considered dangerous by the international Conventions, even though they may pose a serious risk for the environment, such as organic matters. These may degrade and produce toxic gases and thus need to be recovered.

This evaluation is now coming into force in case of new wreckage and the Nairobi Convention on Wrecks Removal helps in solving the potential concerns.

Each shipwreck has to be evaluated in terms of risks and the present document should be considered as general guidelines. Keeping this in mind, as far as “old” wrecks are concerned, the main difficult task is to assess what is really inside a wreck (cargo and fuel). In case the available information is poor, the best procedure is to investigate first the wrecks which have a priority according to experts.

12 European Centre for Ecotoxicology and Toxicology Of Chemicals (ECETOC), 2001. Risk Assessment for

Marine Environment. Technical Guidance Document (TGD) Nr 82. http://www.ecetoc.org/

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5 The Best Available Technologies to Minimize theEnvironmental Risks

While historically marine salvage efforts focused on the protection of private property including the recovery of the damaged vessel and rescue of the cargo or vessel contents, in recent years the protection of the environment has become the primary goal of salvage operations. Environmental specialists are involved early in the process and environmental considerations are discussed in terms of strategies for protection of benthic habitats, of the water column and water surface resources. For non-emergency salvage operations, operations can be scheduled taking into account environmental features with the aim of minimising potential impacts on natural resources and best operational conditions. For instance, operations should be carried out when few sensitive species are present, avoiding critical reproductive periods and considering weather patterns that influence the trajectory of potential releases during operations.

As a matter of fact, facing that the pollution threat posed by a wreck represents a complex situation, where purely environmental considerations may interfere with a series of other problems such as the high cost of the operations, the lack of uniform international regulations, ownership matters, limited information on the ship’s general arrangement and tanks, as well as other technical and safety problems.

Several operations can be carried out in order to evaluate, minimise and eliminate the environmental risks deriving from potentially polluting wrecks:

§ recovery of the entire wreck;

§ sealing the leaking points;

§ controlled release of pollutants;

§ pumping of pollutants;

§ capping of the entire wreck or of the cargo;

§ wreck monitoring.

Moreover innovative solutions for wreck assessment and oil removal are being developed by salvers. Some of the remaining challenges concern new oil sensing and oil sampling instruments for a standard method of surveying the condition of wrecks, analyses of wreck corrosion rates for developing risk stability models and standard procedures to document the volume of oil recovered and to estimate the volume of oil remaining inside the wreck13.


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5.1 Recovery of the entire wreck

As the entire wreck represent itself a source of pollution, its recovery is definitely considered the best option. In the case of the entire removal will be carried out not only oil but also all the different types of potentially hazardous or contaminating materials and substances on board vessels, including oily waste, cargo residues, chemicals in ship’s equipment or machinery or in ship’s store (lubricating and hydraulic oil, solvents, chemical refrigerants, etc.).

Fig. 5-1: Recovery of the entire wreck (source: SMIT Salvage)

Nevertheless there are some disadvantages which need to be taken into account such as the risk of breakage of the wreck and the operational difficulties related to the depth at which the wreck is located. In any case this kind of operation results practical only for relatively intactwrecks.

The decision to recover a wreck is usually due to environmental reasons or to the navigational hazard posed in case it lie in shallow waters.

In the most cases the Owners P&I Club resist paying for wreck removals, the public authority decide to carried out the operation, pay for the removal themselves and then seek compensation from the ownership.

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Fig. 5-2: Recovery of the wreck “TRICOLOR” (source: SMIT Salvage)

The case of the IRVING WHALE successfully lifted in the summer of 1996, well describes the re-floating operations to be carried out when recovery operations of the whole wreck are considered suitable. The IRVING WHALE sank in September 1970 off North Point, Prince Edward island, Canada at a depth of 70 metres, originally containing 7,500 kg of PCBs and an estimated 3,100 tonnes of “Bunker C” oil. The long-term but inevitable release of oil from the barge caused the Canadian Coast Guard to discard the "do nothing" option and following a proper environmental assessment and several public meetings the lift operation took place in different stages.

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Fig. 5-3: Drawing of recovery operation of Irving Whale wreck (source: Environment Canada's Green Lane)

The operation started when the large barge-mounted cranes took up the slack on the lifting cables and began to raise the Irving Whale from the ocean bottom. An underwater video camera on a remote-operated vehicle (ROV) was able to show the amount of deflection or bending of the hull of the barge. Once made sure that the deflection was within acceptable limits, the Irving Whale was raised about two meters from the ocean floor in order to allow the ROV to perform an underwater survey and check whether there was any damage to the hull. The vessel was then raised by the two cranes to just below the surface and water in the vessel was pumped out. Only uncontaminated water was pumped into the sea, the contaminated one was pumped into a separate contractor-provided barge. Following those steps, the semi-submersible transport vessel Boabarge 10 moved underneath the Irving Whale and lifted the vessel to the surface14 15.

14 Environment Canada's Green Lane http://199.212.16.18/whale2/plan.html).15 Brown, C.E., R.D. Nelson, and M.F. Fingas. 1997. Recovery of the Irving Whale oil barge: overflights with the Laser Environmental Airborne Fluorosensor. Proceedings of the Twentieth Arctic and Marine Oil Spill Programme (AMOP) Technical Seminar, Environment Canada,Ottawa, Ontario, pp. 1015-1022.

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Fig. 5-4: Recovery operation of Irving Whale wreck (source: Environment Canada's Green Lane)

Another interesting example is the recovery operations of chemical barge BRIGITTA

MONTANARI sank in the Adriatic Sea on 16 November 1984, to a depth of 82 m, near the city of Sibenik (Yugoslavia). The ship transported more than 1,300 tonnes of vinyl chloride monomer (VCM). The solutions chosen to deal with the wreck were a mix of recovery of entire wreck, controlled release and pumping of pollutants.

Rescue operations began in August 1987, on the assumption that the vinyl chloride monomer tanks had not been damaged. However a leak of VCM estimated at 1 kg/day was detected at the beginning of the operation. The leak was thought to be situated between the left side of the wreck and the deck (the wreck was lying on the right side). Operations began by positioning the wreck on its keel. This operation is often the first step in raising procedures, however it could have been dangerous because of the risk of a sudden spill of a large quantity of vinyl chloride. To release this chemical, a 5 mm hole was drilled in the deck.

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A significant leak of VCM began (estimated at 3 tonnes/day). A concentration of vinyl chloride greater than 5 µg/l was observed in the water column, 300 m from the wreck.

After the chemicals had been leaking for several days, divers connected PVC piping to the holes which had been drilled. The vinyl chloride was piped to the surface where it dispersed into the atmosphere or was burned. The operations were stopped in winter 1987, then resumed in spring 1988. The wreck was raised to a depth of 55 m to be towed underwater to a small sheltered bay near the island of Kaprije, where it grounded. It was then raised to a depth of 30 m, while insuring that the hydrostatic pressure was higher outside the tanks. This precautionary measure was taken to avoid vinyl chloride being released from the corroded tanks. 700 tonnes of vinyl chloride were then pump transferred into another boat (source: CEDRE website).

Fig. 5-5: Recovery operations of the BRIGITTA MONTANARI wreck

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5.2 Sealing the Leaking Points

Sealing the leaking points is often used to minimize the environmental risk as it has the advantage to reduce or eliminate the release of pollutants from the wreck. Nevertheless it is well known that most of the times the leak-sealing operations is only temporary.

In the first half of 2003 leak-sealing operations were conducted on the PRESTIGE wreck both by the Ministry of Transport with the French deep-sea submarine 48 Nautile and the Spanish national oil company Repsol YFP with deep ROVs.

Fig. 5-6: Leak-sealing operations on the Prestige wreck conducted by an ROV (source: IFREMER)

Fig. 5-7: Leak-sealing operations carried out by an underwater operator (Source: French Navy)

Eleven tank leaks were plugged using a variety of tools and materials inserted by a ROV, significantly reducing the leak rate. In spite of this the highly persistent oil continued to leak thus the Spanish government decided to implement oil recovery operations. In many cases sealing operations represent the first option to consider in case of emergency. The technique was utilized also for the HMS ROYAL OAK and the USS MISSISSINEWA wrecks.

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5.3 Controlled Release of Pollutants

The main advantage of the controlled release of pollutants derives from the low costs of the operation. Nevertheless the technique may be performed only with floating pollutants and with ideal meteo-marine conditions.

Fig. 5-8: Recovery operations of the oil released in a controlled manner from the Peter Sif wreck (Source: CEDRE)

In particular when the wreck contains aqueous solutions with limited environmental risks after dilution it may be appropriate to release the cargo under controlled conditions rather than risk a sudden release of the entire cargo. Specialists are called to assist the operations by calculating a safe release rate which takes into account strength and density of the cargo solution, the buffering capacity and dilution rate of the receiving water as well as water depth and the distance down current to sensitive resources. Water quality monitoring is often carried out in order to validate the calculated dilution rates16.

Hereinafter the main operations conducted on the IEVOLI SUN wreck are described to illustrate an example of controlled release of pollutant. Following the wreckage and once an agreement was reached between the French and English authorities, the shipowners and their P&I Club signed a contract with Smit Tak Co. with a view to dealing with the cargo onboard the Ievoli Sun.

The hull was first fully inspected by a ROV, lying the base plates and drilling the outer hull. A camera was used to inspect the space between the inner and outer hull to detect buckling and to measure temperatures beneath the styrene cargo tanks as this would indicate whether polymerisation had started. Once the IPA (isopropylic alcohol) and MEK (methyl

16 Michel J., Helton D., 2003. Environmental considerations during wreck removal and scuttling. USA National Salvage Conference 2003

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ethyl ketone) cargo tanks had been drilled, the product, soluble in water, was allowed to leakat controlled rates. As far as the styrene cargo tanks were concerned, the DBT pump assembly delivered the styrene into the storage barges onboard the Smit Pioneer. The controlled release of the MEK and the IPA, as well as the pumping of both styrene (3,012 m3) and the heavy fuel remaining in the wreck had no measurable effect on the environment (source: Cedre website http://www.cedre.fr/uk/spill/ievoli/wreck.htm).

5.4 Pumping of pollutants

The hot tap technique may result very effective although it generally involves high costs and high tech electronic instrumentation as well as trained personnel. In several cases it has been utilised in order to reduce the risk of oil contamination following wreckage (e.g. PRESTIGE, ERIKA, SS JACOB LUCKENBACH). It represents the most common method of removal of oil from submerged wrecks.

Hot-tap cutting refers to the method of cutting an access hole into a pressurized tank to install a pipe flange or "tap." Several versions of these tools that have been adapted to underwater use can install a pipe flange and cut a hole into oil tanks without spilling oil. Flanges can be mounted onto the hull using drilled bolts or by welding. Lightweight cutting tools have been developed allowing one diver to install and operate the hot tap. Several hot-tap flanges and holes must be installed in a tank to mount the pump, provide make-up water, and insert heating coils. Sometimes it results necessary to heat the transfer line of the pump steam into the oil tank to melt the oil and reduce its viscosity in order to increase its mobility

Fig. 5-9: Hot tapping (source: South Pacific Regional Environment Programme – SPREP)

Fig. 5-10: Positioning of hot tap on the USS Mississinewa wreck (source: Naval Sea Systems Command, US Navy www.supsalv.org/essm/ppt/MISS_Web_Summary.ppt)

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Fig. 5-11: Coil utilised to heat and fluidify hydrocarbons on board the SS Jacob Luckenbach (source: TITAN MARITIME

LLC)

Specialised ROV have been developed for tapping and removing oil from underwater wrecks17. Examples of these machines include the Frank Mohn Company (FRAMO) Remote Offloading System (ROLS) and the Hot Tapping Machine developed by Repsol for the PRESTIGE oil offloading. The ROLS has been used successfully on several wreck oil removal operations, including ESTONIA, IEVOLI SUN, YUIL No.1, and OSUNG No 3., BOW MARINER, and others. These machines allow the removal of oil at water depths unsafe or impossible for divers. Use of these tools can provide more efficient operations than diving by allowing work in poor weather conditions, higher current, and providing 24-hour operations. Powerful ROVs and large support platforms are necessary for successful operations.

The ROLS penetrates cargo and bunker tanks, creating the stations for the safe pump-out of oils and chemicals. The fully-automated process offers a substantial cost advantage over other solutions that rely on expensive and potentially hazardous saturation diving18.

17 Shim, Y.T. 2002. Oil removal operation-Yuil No. 1 & Osung No. 3. Proceedings of the Third R&D Forum on High-density Oil Spill Response, France, pp. 374- 383.18 Haar J. T., 2002. The removal of oil and chemicals from sunken ships at greater depths. The economical solution. Proceedings of the Third R&D Forum on High-density Oil Spill Response, France.

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Fig. 5-12: Remote Offloading System (ROLS) (source: Frank Mohn Company)

Fig. 5-13: Hot Tapping Machine developed by Repsol for the PRESTIGE oil offloading (source: IOSC, 2005)

Low viscosity oils can be removed by using a vacuum pump. The use of a vacuum and long suction hose can simplify the rigging and equipment to be handled by a diver or a salvage crew. Various types of vacuum pumps are available, ranging from a simple diaphragm pump to high volume rotary vacuum pumps. Clogging of the suction hose can be a problem if oil viscosity is high or debris is encountered 19.


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Submersible hydraulic pumps are now commonly used for most surface and underwater salvage operations. Centrifugal pumps have the advantage of being lighter-weight with higher flow rates than positive displacement pumps, and they cannot over-pressurise the discharge hose beyond a shut-off pressure limit. These pumps are not suitable for heavy oils, and emulsification is likely to be high, which may degrade the quality of the recovered product for sale. Such pumps were used to offload Mississinewa of relatively light viscosity oil20. Once the oil/water mixture reaches the surface it needs to be separated in an oil/water separator tank and clean seawater could be returned to the ocean.

The recent R&D activities propose the use of a new technique that seems to be relatively economic and useful also in deep water. It consists in pumping water in cargo or bunker tanks that allows the exit of oil content because its density less than seawater.

Fig. 5-14: Scheme of oil extraction pumping seawater into the wreck (source: Sonsub)

This methodology has been applied by Sonsub for oil recovery from wreck of “SOLAR 1” sunk in August 2006 nine miles south of Guimares island at 630 meters depth. The oil flowed out was collected by an ad hoc cylinder-shaped tank positioned above the holes in the tank; then the shuttle was surfaced for recovery in the tanks installed on the dock of the supply vessel.

20 U.S. Navy Salvage Report. 2004. USS Mississinewa oil removal operations. Naval Sea Systems Command, Washington, D.C.

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Fig. 5-15: Shuttle used to recovery oil from SOLAR 1 wreck (source: Sonsub)

The operation schematised in fig. 6-16 has foreseen:

− drill holes with a core drill in the deck of the tanks where the oil is located;

− install water injection pipes to permit water to enter the tanks;

− install hull valves to control flow from tanks, to be open and closed by R.O.V.;

− lower shuttle to the Solar 1 wreck, then open the valve (by R.O.V.) to commence filling;

− once the shuttle is filled the hull valves are closed and the shuttle is disengaged

− the oil is transferred from the shuttle to the tanks installed on the dock of the supply vessel

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Fig. 5-16: Scheme of oil extraction from SOLAR 1 wreck (source: Sonsub)

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5.5 Capping of the Entire Wreck or of the cargo

This option aims to completely cover the wreck or the cargo in order to avoid the leakage of pollutants components into the marine environment. The advantages of this type of technology are described below:

− isolates the pollutants preventing their dispersion, especially if the capping material has a low permeability to fluids

− protects the wreck from any contact with fishing equipment or other human activities that can cause an augmentation of deteriorating rate;

− reduces the corrosion rate of metals and steels;

− facilitates the transformation of pollutants if the capping material is added with reacting compounds.

The capping of wrecks can be carried out in situ. The capping material should be made of shattered rocks. A preliminary survey is necessary in order to evaluate: the nature and morphology of the sea bed; size, shape and position of the wreck; the state of corrosion of the wreck. Data, such as the position and the size of the wreck are extremely important in order to decide the most effective way of intervening and the amount of material necessary for the capping activities. The quantities may be reduced if the wreck is partially covered by sediments or if it is standing in a tilted position.

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Fig. 5-17: Different capping conditions of a wreck, depending on wreck position.

The capping material can be emitted by means of a tube with a diameter of 0.5-1 m, which is able to transfer the material from the support vessel to the sea bed. The end of the tube is connected to a Heavy Working Class R.O.V. (Remotely Operative Vehicle) specially equipped with underwater cameras and independent engines.

1:25 1:25

1:25 1:25

1:25 1:25

1:25 1:25

8 m

22 m

11 m

16 m

22 m

14 m

16 m

20 m

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Fig. 5-18: Capping of a wreck by a R.O.V.

The granulometry of the external layer of the capping material must be able to resist to the erosive action of external agents and fishing gears. Moreover, in order to avoid the collapse of this coarse material, the presence of internal layers, with a decreasing granulometry towards the sea bottom, is necessary. The granulometric ratio generally employed between two intermediate consecutive layers is 25. The rock used as capping material has a carbonate nature able to create an alkaline environment, which facilitates the eventual hydrolysis of pollutants. Special additives are generally added to the rock in order to accelerate the hydrolysis process further.

Due to the pressure gradient between the wreck and the external part of the embankment, movements of the interstitial water could be generated leading to the spreading of compounds leaking from the wreck. It is therefore necessary to reduce the permeability of the embankment to at least 0,4 mm/h (a typical value for muddy-sandy sediments). This could be achieved through different methodologies:

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− covering the external layer with flexible waterproof sacks filled with cement;

− injection of cement into the embankment;

− use of a special, waterproof and erosion resistant sheet on the top of the embankment.

22 Cabioch F. 2002. Shipwrecks containing hazardous materials: intervention means and techniques available in light of past accidents. Proceedings of the Third R&D Forum on High-density Oil Spill Response, France.

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5.6 Wreck Monitoring and Inspection

In this paragraph the Best Available Technologies to monitor and inspect a wreck are summarised. Obviously, the location or detection of the wreck is the previous step to carry out. In this case the more useful way to accomplish this task is the use of sonars and/or magnetometers. We can imagine two different situations: the wreck is on the bottom; part of the wreck is buried in sediments.

In the first case the more suitable methodology is the use of sonars. The performance of modern sonar is often excellent and allows investigation at a speed of 10 knots with a sweep (scanned width) of 200 to 300 m on each side of the heading followed (the central line is obscured). The wavelength is adjusted according to the depth. Remarkable images can currently be obtained. A differential GPS system allows localisation of the towed lateral sonar to the nearest meter.

Fig. 5-19: The sonogramme of the main wreck of VLCC HAVEN

However, the use of this equipment requires specialist knowledge. Only teams and ships specialized in this type of research can become operationally quick.

In case part of wreck is partially buried the use of magnetometer is also advisable. Performance has been improved on this task, which is widely used in underwater archaeology. In contrast to towed lateral sonar, the object image is only displayed after processing. The image must be therefore verified, which involves a large number of divers or remotely operated vehicles (ROVs). In fact, some geological anomalies or underwater cables can interfere with magnetometer operation. Other techniques are still at the research stage, including the two-dimensional or three-dimensional imaging of buried objects.

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5.6.1 Wreck inspection22

Even if sonar imaging provides us with the position of a wreck on the bottom, only close visual examination (camera, diver or ROV) can provide us with details (location of holes, leaks, corrosion, etc.). The direct examination by divers is depending on the physiological limitations as well as on the national rules. The French Department of Labour authorises tank diving to a depth of 60 meters. From 60 to 80 meters, tank diving with Trimix (nitrogen, oxygen and helium) is possible. Beyond 80 meters, saturation diving is mandatory. However, since execution of this last diving technique is very complicated, the inspection at high depth is rather done using a ROV or AUV (Autonomous Underwater Vehicle).

The limits for a visual inspection depends on physical conditions (current, visibility, etc.). In French, working conditions for divers are defined in the decree regarding "Work in Hyperbaric Environments", dated August 4, 1995 and published in the Journal Officiel de la République Française (Official Journal of the French Republic) on May 2, 1996. Interestingly, the examination of the wreck can be done by divers who have a “B” classification, meaning divers whose "main profession does not consist of underwater work, but who may practice their profession underwater". This concerns several experts like marine biologists, naval engineers, antipollution experts, etc.

The ROV technology has been improved very much in the last 20 years. Companies are specialised in the operation of these vehicles, which are adapted for ships dedicated to underwater research. Some ROVs are specific for observation and equipped with very sensitive cameras. Others are designed for seabed operations (maintenance, civil engineering, etc.). Data are transmitted via fibber optics and conductor cables. For deep ocean research specialized companies use combined systems. Thus the MV Derbyshire, a 157,000 ton ship that sank to the south of Japan at a depth of 4,200 meters, was found by towed lateral sonar (DSL 120 . 120 kHz) at 100 meters above the bottom (1km sweep). Located debris was then filmed and photographed. 137,000 images were produced in 26 days and precise sensor positioning allowed image-by-image reconstruction of the sea bottom (2 km x 3.5km). The ROV Jason was then used at very specific sites of the wreck in order to film 378 video cassettes (high-definition TV, digital Betacam, Betacam Hi-8).

The future for AUVs (still called Unmanned Underwater Vehicles or UUVs) includes many uses and will allow deep water research (beyond 200-300 meters) at higher speeds (1 to 4 knots), along with very precise positioning. The problem is still battery autonomy. A hybrid vehicle (AUV and ROV) - the AutRov is currently being tested by Fugro NV. In this concept, the AUV serves as a platform for the ROV. Once this system is operational, it will decrease the need for highly specialized tender ships.

The quality and availability of underwater video images have been improved by digital imaging. This technology allows the use of miniature cameras (some are no bigger than a watch). These cameras have a very high resolution, they take 360° images and include built-in lighting. They can thus be assembled on an ROV and supplied through a power supply

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cable that is tens of meters long (bilge and reservoir observation). These images are of course available in real-time.

As soon as a wreck occurs involving cargo that is transported hot (bitumen and heavy fuel oil), the availability of high-temperature underwater cameras should be verified to help estimate the quantities remaining in the wreck. Workers have a few days to perform this operation, and its success of course depends on the temperature differential (cargo temperature/water temperature).

5.6.2 On-site measurements and wreck monitoring

Pollutant detection can be performed on-site, via samples or destructive methods. Concerning chemical pollution, water and sediment samplers are available on the market. These samplers must be retrieved for analysis. However, the presence of a pollutant can be observed behind a wall by drilling holes via "stud shooting" and plugging them with a softwood bung if the result of the test is positive. This test can be done by traditional sampling or by introducing a probe such as used for measuring hydrocarbon thickness in bore holes for cases of land pollution.

It is important to take into account the development, in the last years, of non-destructive oil sensing instruments, such as gamma-ray or neutron back-scatter instruments. This instrumentation may allows for rapid assessment of oil volumes of a wreck. The increasing use of this technique may now allow for a relatively low-cost survey of potentially polluting wrecks. The use of classic techniques to estimate the quantity of hydrocarbons includes the direct probing of reservoirs, after drilling through the walls, to find the water/hydrocarbon interface and estimate their actual fill levels.

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Fig. 5-20: Example of a probing test conducted on the SS Jacob Luckenbach wreck (source: TITAN MARITIME LLC)

The Neutron Backscattering System (NBS), firstly developed by SMIT Salvage, is capable to detect levels of oils and chemicals in sunken vessels using a neutron backscattering device which surveys a wreck’s tank and provides a level indication of pollutants inside by identifying changes in hydrogen density in liquids and gases. This instrumentation is very useful because give information on the wreck content without operate holes, often timing and money consuming.

Another important measure is the metallic wall thickness, useful for old and corroded wrecks as well as to determine the presence of structural reinforcements. The company Cygnus (UK) manufactures an underwater sensor used to measure it (www.cygnus-instruments.com).

WRECK MONITORING

An underwater monitoring system could be placed around a potentially polluting shipwreck with the aim to control and verify eventual polluting product leaks. The system is based on a set of autonomous stations, communicating through an acoustic network, fitted with convenient sensors able to detect oil or chemical pollution. The system has to be flexible to allow the installation of modular sensor subsystems.

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A prototype system has been developed and tested at sea with the ROSE project financed by French Research Ministry with the participation of CEDRE and other French Institutions. The test has been conducted in Douarnenez bay (Brittany) at a depth of 25 meters from June to September 2006. The pollution sensor employed was an hydrocarbon fluorometer TRIOS enviroFlu-HC. Other environmental sensors (CTD, etc.) were mounted to give a prediction of the diffusion of an eventual pollution.

Fig. 5-21: prototype system developed and tested at sea during the ROSE project

Fig. 5-22: Deployment and recovery of prototype system

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The system seems to be adaptable also to work at great water depth, for long monitoring. The possible information recovery modes are: acoustical interrogation on site, pop up buoy releases, permanent bi-directional acoustic and radio link.

Another monitoring system has been developed by NURC (NATO Underwater Research Centre): the SEPTR (Shallow water Environmental Profiler in Trawl-safe Real-time configuration). The SEPTR is an underwater platform developed at NURC to assist oceanographic modeling and rapid environmental monitoring research programs, which broadcasts measurements in real-time using satellite communications. The SEPTR system is made by two units linked together with a tiny cable: a micro-controller based bottom platform, the "bottom unit", firmly anchored to the sea bottom through a reinforced concrete ballast, which houses an ADCP (Acoustic Doppler Current Velocimeter), a wave/tide gauge, an ambient noise sensor array, and a messenger. The messenger is a water column profiler buoy system that houses CTD sensors and performs autonomous vertical CTD profiled at depths down to 100m, with a maximum of 360 profiles, (up to 12 per day).

Fig. 5-23: Positioning and functioning of SEPTR system (source: NURC www.nurc.nato.int )

The SEPTR system could be adapted for wreck monitoring mounting a messenger with an hydrocarbon fluorometer.

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5.7 Factors Influencing the Choice of Interventions to Minimise the Environmental Risks of PPSWs

The decision of what kind of intervention to carry out to minimise the environmental risks of PPSWs depends from a series of factors like:

• the wreck status of conservation: i.e. influences the decision to recover the entire wreck;

• the type of pollutants: the marine behaviour of pollutants (float, solve, evaporate, sink, etc.) could influences the choice of pumping;

• the depth of seabottom: the augmentation of depth enhances the costs as well as the technical problems;

• the environmental characteristics of the site. i.e. influences the decision to carry out a controlled release.

The costs evaluation of the interventions is often the main aspect that the public administration in charge to make a decision takes into account. The factors affecting the cost entity of interventions are:

• the depth of seabottom: choice of the use of professional divers or mechanical tools such as R.O.V.;

• sea and weather conditions: size of supply vessels and number of stand-by days;

• condition and type of wreck: complexity of underwater work;

• volume of pollutants: number of work days;

• distribution of pollutants: number of work days.

Moreover, the costs related to the pollutants disposal have to be take into consideration.

The decision to minimise the potential risk posed by a sunken vessel must be based upon a sound risk assessment and a well-developed cost/benefit analysis because any salvage effort is usually expensive, time-consuming, and risky. The cost/benefit analysis must assess the potential environmental and biological impacts of any pollution from the wreck as well as the socioeconomic implications of any spill and remediation costs. Consequently, a consideration should be taken into account before the assumption of any decision related to remedial activities: whether the potential environmental impact and risks posed by the oil or other pollutants contained within the sunken vessel outweigh the cost of the mitigation action. In this evaluation also the economic damage and social consequences caused by repetitive or massive spills from a shipwreck need to be considered.

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As reported in the IOSC publication23, in a very rough estimate it is possible classify the interventions on the basis of their technological difficulties and costs evaluation as follow:

• Simple (1 - 3 US $ million): wreck in shallow and protected water. Local mobilisation of tools;

• Moderate (2 - 5 US $ million): wreck at moderate depth (20-50 meters) in an area with some weather restrictions. Regional mobilisation of tools;

• Complex (5-20 US $ million): wreck at deep depth (50-250 meters) in an area with weather limitations, in open water. A poor wreck condition. Long mobilisation of tools;

• Higly complex (20 - 100 US $ million): wreck at extreme depth (>250 meters) in an area with weather limitations, open water. A poor wreck condition. Long mobilisation of tools

A QUESTION OPEN TO A FUTUR DEBATE IN INTERNATIONAL FORA: How can the public Administration in charged of controlling, monitoring and verifying the underwater operations conducted on a potentially polluting shipwreck be sure of the good conduction of activities?

The control of operations at several tens of metres depth is made only through the observation of photos and videos realised by the private Society in charged of the underwater operation. But how is it possible to verify for example that all the tanks of an oil tanker have been emptied? At least in Italy, underwater operators of a public Administration may work at depths less than 50 meters.

Probably, at the moment an element of doubt on the efficiency of results will always remain.


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