198 6th International Conference on Sustainable Development in theMinerals Industry, 30 June – 3 July 2013, Milos island, Greece

Marine Aggregates deposits - MARE project

M. Stamatakis, S. Poulos, A. Tsoutsia, N. Papavlassopoulou, A. Karditsa andM. AnastasatouUniversity of Athens, Faculty of Geology & Geoenvironment, Panepistimioupoli Zografou, Athens,Greece

A. Velegrakis and T. HasiotisDepartment of Marine Sciences, School of Environment, University of the Aegean, University Hill,Mytilene, Greece

V. Kapsimalis and G. RoussakisHellenic Centre of Marine Research, Athens, Institute of Oceanography, Anavyssos, Greece

ABSTRACTThe usage of Marine Aggregates (MA) particu-larly that of sand and gravel, is of great im-portance for the construction and raw materialindustry. Although in many European countries(e.g., United Kingdom, Belgium, Denmark) theuse of MAs has been established over the pastdecades, in Greece, there are no systematic stud-ies for their reserves and quality, despite the factthat the overall coastal geological backgroundfavors their occurrence.

The scope of the present contribution is topresent the outlines and some preliminary re-sults of the research project that is currently im-plemented within the THALES Program (Minis-try of Education, Lifelong Learning and Reli-gious Affairs). The project investigates theGreek continental shelf, including the CycladesPlateau, for the identification, prospecting,dredging, and usage of MA deposits. Its mainobjectives are: (i) compilation and integration ofthe available information concerning prospect-ing, dredging, and usage of MAs in Greece andin Europe; (ii) MA prospecting techniques andmethods (transfer of knowledge); (iii) sedimen-tological characteristics of the MAs occurring inGreek waters; (iv) an assessment of the environ-mental issues related to MA prospecting anddredging in Greece; (v) the exploitation of theproject’s results (e.g., industrial use); and (vi)the training of young researchers in innovativerelated research aspects.

1. INTRODUCTIONMarine aggregates are sands and gravelsdredged from the seabed and are used in con-crete and mortar manufacture, asphalt and coat-ed products, block making, drainage and fill ma-terials, leisure and sport facilities and beach re-plenishment (BMAPA, 2004). Over the pastfour decades the MA dredging industry devel-oped into an integral part of the materials supplyfor the construction industry worldwide (Ano-nymous, 2003). Aggregates are usually obtainedfrom quarrying on land, from the recycling ofdemolition waste and from secondary sources,like blast furnace slag and pulverized fly ashfrom power stations. Quarried and dredged ag-gregates are known also as “primary” aggre-gates (BMAPA, 2011) in order to be distin-guished from the secondary (recycling) aggre-gates; the latter are regarded of lower quality, atleast for structural concrete (e.g. Malešev et al.,2010).

The progressive depletion of land sources ofconstruction materials poses increasingly acutesupply problems to the construction industry.Besides, in several places around the world, in-cluding Greece, mining activities and tourismhave come into conflict. In addition, environ-mental regulations may cause exploitationschemes to evolve towards alternative sourcesthat include also the exploitation of marine de-

6th International Conference on Sustainable Development in the 199Minerals Industry, 30 June – 3 July 2013, Milos island, Greece

posits of sand and gravel (e.g., Fookes et al.,2001).

Nowadays more than 50 M m3 are extractedannually, offshore the NW European countrieswith more than the half in UK and The Nether-lands (Velegrakis et al., 2010). In 2004 59 Mm3

of marine aggregates were extracted, totallyfrom European Countries, among which 23.6Mm3 from the Netherlands and 13 M m3 fromUnited Kingdom (Lindsay, 2009). Comparingthe land-laid and the marine deposits, an advan-tageous feature of many marine sands is the lowsilt content, especially in dredged aggregates,where much of the fine material is washed outby the dredging (Prentice, 1990). Disadvanta-geous features are the presence of salts - halite[NaCl] - and shell fragments. Halite is a non-desirable constituent in the construction materi-als, so the sea-dredged aggregates have to bewashed out with freshwater, before use.

Generally, the aggregate extraction maycause direct (mainly arising from the dredging,which disturbs the seabed or from the removalof deposits and the creation of the suspendedsediment plumes in the water column duringsediment collection into the vessel) and indirect(as a result from the subsequent deposition ofsediment particles from the water column on tothe seabed) impacts. The effects of shipping ac-tivities such as vessel movements, boat noiseand vibration on marine wildlife, arising fromextraction are also classified as indirect impacts,but tend to be very minor. The main cumulativeeffects relate to the removal of seabed deposits,is focused on a relatively small number of habi-tat types (Tillin et al., 2011).

The extraction of the MA follows: (1) thediscovery of the deposit (often linked to olderworks, scientific or not, e.g. mapping); (2) thestudy of deposit’s characteristics (prospecting)by acoustic devices (multi beam, side-scan so-nar, seismic and ground-truthing, corer, grab,video); and (3) the environmental impact of itsextraction that deals with the selection of dredg-ing equipment, trying to minimize the environ-mental impact on the marine ecosystem (ICES,2005).

Furthermore, offshore dredging has in somecases triggered accelerated beach erosion; this,combined with the general rise of sea-level and

the consequences of exceptional-strengthstorms, have worsened erosion and greatly dis-turbed (occasionally irreversibly) the local sed-imentary budget and transit.

Before the MA extraction, the Active DredgeZone (or Area) (ADZ or ADA) is defined, with-in which a production license for dredging hasto be obtained aiming to minimize as far as pos-sible the environmental footprint of the dredg-ing operation and the potential for spatial con-flict with other marine users(http://www.bmapa.org). The most commontypes of dredging vessels for MA extraction arethe trailing suction hopper dredgers that operatevery much like a floating vacuum cleaner andthe stationary suction dredgers that are used insand and gravel winning operations and largereclamation projects. Technological progressand continuous improvement of sophisticatedequipment permit greater efficiency in, andgreater depth of, dredging operations (Charlierand Charlier, 1992). Subsequently, the MA us-age may addresses several issues, as in the caseof industrial materials, chlorides and shell con-tent for preventing alkali-silica reaction (BRE,2008).

In the case of Mediterranean countries, quan-tities of sand are extracted mostly from the sub-aerial part of the beach zone and related sanddune fields arbitrarily and for building usuallypurposes; this action is illegal, as it is related tothe beach zone stability (Velegrakis et al.,2010). On the other hand, the presence of relictsand deposits has been reported in the case of thecontinental shelf of the northwest and northeastAegean Sea by Lykousis et al. (1981) and Perri-soratis et al. (1987), respectively.

The present demand of Greek industry forMA (siliceous or calcareous) concerns the pro-duction of building and refractory materials, e.g.cement clinker, mortars, cement floors, cementscreed production, laying ceramic setts, drain-age courses and athletic constructions. Further-more, in Greece MA industry pertains to theproduction of portable and non-portable filtersand the use of silicate sands in various environ-mental applications, such as hydroponic cultiva-tions/soil amendment. Moreover, Greek compa-nies produce more than 100,000 tons annuallyof calcareous fillers, with most of these being

200 6th International Conference on Sustainable Development in theMinerals Industry, 30 June – 3 July 2013, Milos island, Greece

exported. In addition, calcareous fillers of highpurity are used in animal feeding, as an addi-tional component, in many European countries.On the basis of the above, the present demandexceeds annually 300,000 tons. Moreover, ma-rine sands and gravels would be also used inbeach zone replenishment in order to mitigatebeach zone erosion (EUROSION, 2004; Alex-andrakis et al., 2009).

2. THE MARE PROJECT

2.1 Scope-objectivesThe innovative research objectives of the pro-ject are summarized below:- The identification of (possible) locations of

MA deposits, on the basis of the geologicaland morphological evolution of the Greekcontinental shelf (and related subaqueousplateau), the lithology of the drainage riverbasins and sediment transport pathways.

- The application of the most appropriate geo-physical methods for the acquisition of sea-bed data for MA prospecting, with referenceto the international practice and in relation tothe local marine/seabed conditions.

- A thorough investigation of the sedimentolo-gy (grain size, mineralogy, etc.), composition(chemical) and other physical characteristicsof the identified MA deposits.

- The selection and application of the most en-vironmental-friendly dredging techniques,according to the Greek marine conditions,with reference to the international experi-ence.

- The development of a MA prospecting /dredging protocol on the basis of the interna-tional practice, European legislation, and inaccordance to Greek Law.

- An economical assessment of MAs exploita-tion (in relation to market demands) in termsof their availability (quantity) and their par-ticular sedimentological composition.

- The high level training of young researchers(MSc and PhD candidates and Postdoctoralresearchers) in multi-disciplinary issues as-sociated with MAs exploitation.

2.2 Methodology - project’s materialisationThe proposed research extends over 42 monthsand is organised into 6 main and interrelatedWork Packages (WP), which are shown in Fig-ure 1.

The implementation of the project presents aparticular challenge due to its multidisciplinarycharacter, which is satisfied through the contri-bution of the following four Research Teams(RT) under the leadership of:RT-1: Mineral Deposits & Economic Geology -NKUA (Prof. M. Stamatakis);RT-2: Oceanography & Sedimentology -NKUA (Assoc. Prof. S.E. Poulos);RT-3: Geo-Marine Environment - UOA (Prof.A. Velegrakis); and,RT-4: Marine Geology & Geophysics - HCMR(Dr V. Kapsimalis, Researcher) (see alsoFig. 1).

3. PRELIMINARY RESULTSOn the basis of existing information regardingthe geological environment of the inner conti-nental shelf (including the Cyclades Plateau),coastal lithology and the locations of active riv-er mouths, the locations of potential MA depos-its are presented in Figure 2.

Thus, future areas of research are: Rhodos Is-land (SE Aegean Sea), Kos Island (SE AegeanSea), Lesvos Island (East Aegean Sea), Thraci-

Figure 1: Graphical presentation of the main structure ofthe project.

6th International Conference on Sustainable Development in the 201Minerals Industry, 30 June – 3 July 2013, Milos island, Greece

an Sea (NE Aegean Sea), SE Evoia Island,Kissamos-West Crete Island (South AegeanSea), Gournes-Iraklio Crete and KiparissiakosGulf.

Issues that must be addressed and evaluatedfor each location separately are the territorialwater extents, the existing submarine infrastruc-tures (e.g. cables, pipelines), the presence of Po-sidonia almost all around the Greek coasts up toa mean water depth of 30m, the coastal rockyrelief, the narrow and relatively small in aerialextent regions between the 30m and 50m iso-baths and the reduced recent sediment thicknesswith increasing water depths". Selected sidescan sonar images and sub-bottom profiles fromthe Greek shelf are presented in Figures 3, 4 and5. In Figure 3, the side scan image reveals theboundary between a sandy bed and Posidoniameadows that are environmental sensitive andthey are regarded as protected species. In figure4, the sub-bottom (boomer type) profile shows athick layer of sandy material to be present inwater depths >25-30 m; such deposits are re-

garded suitable for exploitation if there are notother environmental constrains.

In Figure 5, the side scan sonar image revealsseabed micro-relief that is probably related tonear bed current activity, while the subbottomprofiles suggest the presence of a surficial sandylayer (2-5m in thickness) over the acousticbasement.

4. CONCLUDING REMARKSThe gathered information and the preliminaryresults of the MARE project are promising to-wards the identification of MA deposits inGreek waters that may be proved suitable forexploitation. Thus, the expected benefits will berelated to both the local communities and theoverall national (Greek) economy, by providingthe appropriate volumes of aggregates in orderto satisfy the increasing demand for raw materi-als for the Greek construction (silicoclastic de-posits) and material (silicoclastic and calcareousdeposits) industry, as well as for beach nour-ishment.

Besides, as a potential impact of the wholeeffort of MA prospecting and dredging, is thecreation of new working places (employment),since it requires scientific involvement (e.g. ma-rine geologists, environmentalists, engineers)for the prospecting and specialized vessels andport facilities for the dredging and temporarystorage onshore. At an international level, thegained experience and knowledge could betransferred to other countries of the easternMediterranean, which have analogous demandsfor MAs. As additional benefits may be regard-ed the acquisition of detailed geomorphologicalinformation of many parts of the Greek conti-nental shelf, together with the training of youngresearchers in complex issues involved in MAprospecting-dredging-usage.

ACKNOWLEDGMENTSThe project MARE (MIS: 375655) is supportedby the co-finance of the European Union (Euro-pean Social Fund - ESF) and Greek nationalfunds through the Operational Program “Educa-tion and Lifelong Learning” of the NationalStrategic Reference Framework (NSRF) - Re-

Figure 2: Marine aggregates positions in Greek MarineAreas: 1: Kos Isl. - Kardamena, 2:Chalkidiki- Pefko-chori, 3:Naxos Isl. Kleido, 4: Evoia-Akteo, 5: Evoia-Ag.Dimitrios, 6:Lefkada Isl.- Ag. Nikitas, 7: Lefkada Is-land- Ag. Ioannis, 8: Aleksandroupoli - Mesimvria, 9: Ti-nos Isl.- Rohari, 10: Tinos Isl.- Ag. Sostis, 11: IraklioGournes, 12: Evros Delta, 13: Nestos Delta, 14: Strimo-nas Delta, 15: Aliakmonas Delta, 16: Pinios (Th) Delta,17: Sperchios Deta, 18: Aksios Delta, 19: Mor-nos Delta,20: Evinos Delta, 21: Acheloos Delta, 22: Alfios Delta,23: Pinios (Pel) Delta, 24: Kiparissiakos Gulf, 25:SikinosIsland-Dialiskari, 26: Mitilini Isl.

202 6th International Conference on Sustainable Development in theMinerals Industry, 30 June – 3 July 2013, Milos island, Greece

search Funding Program: THALES (Investingin knowledge society through the European So-cial Fund).

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Lykousis, V., M.B. Collins and G. Ferentinos, (1981).Modern sedimentation in the NW Aegean Sea. MarineGeology, 43, 111-130.

Lindsay, M. (Dr), (2009). Marine Sand and Gravel Ex-traction- Impacts and Mitigation, Eco-friendly Dredg-ing in the Modern Word, 13-14 October, St Peters-burg, Russian Federation.

Perrisoratis, C., S.A. Moorby, C. Papavasiliou, D.S. Cro-nan, I. Angelopoulos, F. Sakellariadou and D. Mi-tropoulos, (1987). The geology and geochemistry ofthe surficial sediments off Thraki, Northern Greece.Marine Geology 74: pp. 209-224.

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Figure 5: 3.5kHz sub-bottom profiles (a, b) and side scansonar image (c).

Figure 3: Side scan sonar image.

Figure 4: Subbottom ("boomer" type) profile.

6th International Conference on Sustainable Development in the 203Minerals Industry, 30 June – 3 July 2013, Milos island, Greece

Velegrakis, A., A. Ballay, S. Poulos, R. Radzevicius, V.Bellec and F. Manso, (2010). European marine aggre-gates resources: Origins, usage, prospecting anddredging techniques. Journal of Coastal Research, 51,pp. 1-14.