impact on the coastal environment of marine aggregates mining

Intern. J. Environ. Studies, 2002, Vol. 59(3), pp. 297-322 Q Taylor & Francis~ Taylor &.Francis Group

IMPACT ON THE COASTAL ENVIRONMENTOF MARINE AGGREGATES MINING

ROGER H. CHARLIER

Free University of Brussels (VUB.), 2, Avenue du Congo (Box #23),B-J050 Brussels, Belgium

(Received in final form 2 J July 2001)

The higher demand for construction materials and the depletion of land sources, coupled withsterner environmental restrictions, led suppliers to turn to the sea, particularly to the near-shoreareas. Several of these mining operations are illegal, many are damaging for the coastal andoff-shore environment, some are threatening coast lines including in such sensitive areas asthe coral reefs. A case study is examined for Australia.

Keywords: Sand; Gravel; Dredging; Benthos; Geographical round-up

1. AGGREGATES

To a geologist, and generally an engineer, aggregates are mineral materialssuch as sand (siliceous or carbonaceous), gravel, shell, slag, broken stone,with which cement or bituminous material can be mixed to produce con-crete or mortar. A distinction is made between fine aggregates (grains dia-meter smaller than about 1cm) and coarse aggregates (grain diameter largerthan 1cm).

Aggregates retrieved from the marine domain include such unconsoli-dated materials as sands, gravels, shells, products of coral origin and refrac-tory muds [1, 2]. Shell deposits have been worked off the Isle of Man, inIceland (Faxa Bay) and The Netherlands (Wadden Sea). Coral and coralsands have similarly been exploited in Hawaii, Taiwan, the Maldives (In-

ISSN 0020-7233 print; ISSN 1029-0400 online (Q 2002 Taylor & Francis LtdDOl: 10.1080/00207230290026917

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298 R. H. CHARLIER

dian Ocean), Bali and the Bahamas. An 198 acre (82.5 ha) artificial islandwas built in the Bahamas from dredged aragonite. It is the site of aragonitedredging operations that produce about 1500 metric tons per hour. Theisland emerges a shallow sea between 2 and 3 m deep, but after a decadeof mining, the depth has reached from 5 to 6 m. Operations may have tobe suspended to protect fishing grounds.

By volume these marine products represent the least economic value, but

in importance they have grown considerably over the last forty years asrestrictions on quarrying land deposits dried up such sources (Tab. I).Furthermore constant technological advances in methods and equipmenthave made greater depths accessible, while the more sophisticated equip-ment permits ever greater efficiency, and thus better economic returns(Tab. II).

Sand and gravel account for 40% of non-hydrocarbon off-shore minerals.The economic importance of aggregates whether from beaches, near-shorebanks or bars or lower sea-bed stands-recent or relict--dating from thePleistocene is difficult to assess [3]. The demand doubled by 2000 fromthe 1958 amount of 684 billion (milliard) tons. Reserves are estimated atleast 15 billion tons, possibly 50 billion. Twenty years ago (1984) some774 million tons were used, or sold; their value was then $2.87/ton or$2,225 million, but price climbed about 20% by 1988 ($3.38/ton) andquantities to 923 million tons, worth $3,126 million (Fig. 1).

Cruickshank and Hass [4] estimated the US cumulative needs for 2000 atapproximately 77 billion tons, rising eventually to about 1200 billion tons,while US land and marine reserves were believed to amount respectively to67 and 1690 billion tons, with the world's reserves approximately 333 and31,000 billion tons, respectively. Thirty-five years ago US and British sandand gravel of marine origin was worth $10010, representing only 0.6% ofthe US production alone 20 years later (1986). Total of extracted dissolvedunconsolidated minerals, principally heavy minerals, iron and tin, were thenworth $180 million [4].

TABLE I Granulates: needs and reserves, 1976. Cruickshank & Hass [4] [in billions tonnes]

United States World

Annual needs, 1970Cumulative needs, 2000Land reservesMarine reserves

1.0276.7067

1690

7.45535333

31,000

MINING AGGREGATES 299

TABLE II Production value of offshore minerals [7, 30, 31]

ProjectedProduction % Jizlue production

value (1972) from ocean value (1980)

Subsurface soluble minerals and fluids:Petroleum (oil and gas) 10,300 18 90,000Frasch sulphur 25 33Salt 0.1Potash NoneGeothermal energy NoneFreshwater springs 35

Surficial deposits:Sand and gravel 100 <ILime sheIls 35 80Gold None 2000Platinum NoneTin 53 7Titanium sands, zircon, 76 20

and monaziteIron sands, restarted 10 <IDiamonds (closed down in 1972) NonePrecious coral 7 100Barite I 3Manganese nodules (production

expected by early 1980s)Phosphorite None

Subsurface bedrock deposits:Coal 335 2Iron ore 17 <I

Extracted 1Tom sea water:Salt 173 29Magnesium 75 61Magnesium compounds 41 6Bromine <20 30Fresh water 51 2000Heavy water 27 20Others (potassium salts, calcium I

salts, and sodium sulphate)Uranium None

Total 94,000

2. MUDS, CORALS AND SHELLS

Muds have been dredged for decades, particularly those containing tin;Malaysian and other South East Asia areas have been and currently stillare actively mined [5]. The muds, of course are unconsolidated materials,not aggregates but there is a certain parallelism of environmental impact

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Major oceanic m'meral sites [23, 30]

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with sand retrieval operations. Separation of the tin ore is commonly per-fonned at sea aboard the mining vessels, and wastes are discharged over-board. These are particularly harmful to marine life, especially to filterfeeders. Building of feeder benns near-shore, for beach restoration and/ormaintenance are likewise a problem for benthic species.

Removal of coral, though not as widespread as sand and gravel opera-tions, has had dramatic consequences for both marine life and shoreline sta-bilization. A Year of the Reefs recently (1997) organized evidenced to whichextent damage had spread. Satisfying the tourists' curio-hunger was but aminor cause in reef destruction, but the search for construction materialsis a source of major concern and damage. Corals protect thousands ofmiles of coasts against erosion and to some extent stonns.

Corals playa very important ecological role in that they participate in theplanetary balance of calcium and carbon flow, thus are involved in longtenn climate changes. Their lagoons are home to an exceptional richfauna and flora, a unique worldwide patrimony. They live in endo-symbio-sis with zooanthellae (single-cell algae) and influence photo-calcification,co-evolution, and biodiversity. As they respond rapidly to quantifiable me-tabolic and/or structural changes, also assimilate in their skeleton specificsubstances retrieved from the sea-water and bear thereby witness to past cli-matic and other modifications, corals are indicators of ecological stress.

When the decision to lengthen Den Passar airport runways on Bali wastaken, with no land-based sources of building materials readily available,local materials providers went to sea and removed coral from the reefs.The runways were built allright but beach-side luxury class hotels that en-joyed magnificent vistas and whose prized amenities included wide beachesat their doorstep, found themselves "with their feet in the water" .A satisfac-

tory remedy has not yet been devised. Meanwhile the reef, home to myriadsof sea creatures, lost much of its denizens and even more of its biodiversity.

Shells have been likewise exploited in these regions for a very long time,but it is the tourist demand for abalone shell that has placed the animal injeopardy.

3. SAND AND GRAVEL

Mining and dredging of sand and gravel have entrained major environmen-

tal effects and occasionally petites causes have grands effets. Americans

302 R. H. CHARLIER

claim that the first beach nourishment operation took place in California[6]. The French pride themselves of having introduced the approach toWestern Europe at La Croisette, near Cannes. But the Turks credit theRomans: Marc-Anthony had a white beach built on Sedir Island in GokovaBay for Cleopatra, who shipped the oolithic sand from Egypt. The2000-year old beach is now suffering erosion because tourists sate theirsouvenirs-hunger by picking the oolithes (Fig. 2).

Sand and gravel have been, and are, exploited directly on beaches inJapan and Australia for instance, to recover heavy minerals near-shoreand offshore to retrieve diamonds for instance along the coasts of southernAfrica, or for construction purposes as along the United States', British andFrench Atlantic coasts, or on the Belgian North Sea coast to supply artifi-cial beach nourishment material but also in ever deeper waters as technol-ogy now permits and environmental restrictions currently compel. Suffice itto mention in the latter instance the use of marine aggregates to build arti-ficial islands in Japan (airport extension), in the Beaufort Sea (hydrocar-bons retrieval), The Netherlands (waste disposal), and for potentialhuman establishments (de la Rougerie and Bos Kalis schemes, e.g. in Indo-nesia) [7].

Sand and gravel may well be considered the most important non-hydro-carbon offshore mineral extracted close to human settlements in the UnitedStates, Western Europe and Asia. Thirteen million tons were already ex-tracted yearly by the United Kingdom ten years ago; the amounts extractedfrom the North Sea at depths of less than 30 m were estimated as approx-imating 50 million tons. This represented in 1992 a sediment deficit be-cause the amount of sediment carried to the North Sea by majorcontemporary rivers did not reach that amount, with a resulting physicalimpact on the shoreline and the beaches, and a biological impact on thebenthos (Fig. 2).

4. DREDGES

Several types of dredge[r]s have been on the market for a long time. Usedfor instance to keep navigation channels open or maintain sufficient draughtdepths, they also ply the coasts and the deeper seas to get sand and gravelsupplies.

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FIG URE 2 Hard minerals of the offshore [3 1].w0w

304 R. H. CHARLIER

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FIGURE 3a Trailing suction hopper dredger

The cutter suction dredger is the most common dredger; it has a cutter-head at the suction pipe's entrance which agitates soft materials {or cutsharder materials}. The dredging pump creates a vacuum in the suctionpipe and draws the material up the pipe and through the pump. Dischargeis achieved by pumping through a pipeline. Modem versions have a dred-ging pump sited well below the water level and thus reducing suction col-umn height. The operation is continuous, interrupted only because of vesseladvance or change of discharge site. The dredger is connected to shore by afloating pipeline.

The stationary suction dredger, very commonly used to mine sand andgravel deposits is somewhat older. The dislodged deposit is transportedby a water current kept in motion by the sand-pump (viz. dredgingpump). The suction tube hangs in a well, dredging is done at anchor,

1. CUTTER 9. FLOATING PIPELINE2. CU'I'TERSHAFT 10. SIDE WIRES3. CUTTER ENGINE 11. SIDE WINCHES... LADDER 12. WINCHES ANCHORs. ENTRANCE SUCTION PIPE BOOMS6. SECTION PIPE 13. ANCHOR BOOMS7. SANDPUMP 14. LADDER WINCH

8. RECLAMATION PIPE 15. SPUD WINCHES


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discharge occurs sideways into a barge, or into a floating and shore pipe-line. Dense sand is desegregated at the suction pipe's entrance.

The stationary suction dredgers will only function profitably in sandlayers at least 6 m thick.

Equipped with two suction pipes designed to trail over the vessel's side,the trailer dredger (a.k.a. trailer suction hopper dredger) has a dredgingpwnp placed in the hull and discharging into a hopper; the sediment's par-ticles settle and the water is discharged overboard by high pressure waterjets. Dredging depths capabilities vary with vessel's sizes. More modern

306 R. H. CHARLIER

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1.. ENTRANCE SUCTION PIPE2. SUCTION PIPEJ. HIGH PRESSURE WATERJET4. SANDPUMP5. SPRAYING TUBE6. HEAD LINE7/8. SIDE LINE9. AFTER LINE

FIGURE 3c Stationary suction dredger.

versions have the pump placed on the suction pipe well below water levelthus reducing the suction column height. The hopper capacity ranges from300 to 11,000 m3.

Discharge is usually through valves or sliding doors, or by pumping fromhopper into a pipeline at specially designed berths. The dredger's splithop-per version discharges by splitting.

Some trailing suction hopper dredgers can be converted into stationarysuction ones by replacing the trailing suction tube by a suction tube point-ing ahead.


1. BUCKET2. STICK3. BOOM4. FRONT SPUDS5. AFT SPUD

FIGURE 3d Backhoe dredger.

The backhoe dredger (Fig. 3d), defacto an excavating machine mounted on

a pontoon, penetrates the deposit from the top of the face, unless the machine

sits atop the face when digging occurs from the face's bottom upwards. Pon-

toon and hoe are frequently integrated. Its maximum operational depth runs to

18 m. Boom, stick and bucket capacity have to be adapted to the dredging

depth. This platform-and-suction-dredge stands on three legs that reach the

ocean floor at the operations site, and "walks" to another site at a speed of

8 m/h when a deposit has been sufficiently tapped [8].Originally limited to 23 m deep deposits, the machine has been adapted

to greater depths.Barge unloading dredgers raise water-and-sediment mixtures from

barges, by suction, and deliver them via shore pipeline to specific sites.

Large quantities of material can be delivered over long distances. Elevator

barges with sloping hold-sides and closed bottoms transport sediment to

the dredger.Dredging companies frequently minimize the impact of their operations

and dispute their lasting effects; sand banks' and deeps' mining is subject to

national, and international, regulations, but authorities often either lack the

308 R. H. CHARLIER

MINING

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CHICAGO, ILLINOIS

FIGURE 3e Hopper dredger.

will, the political courage, or the means to enforce laws. The consequencesof such lacksadasical attitudes may be regretted in the not-so-distant future.

Among dredges, hydraulic dredges combine the high density and lowturbidity characteristics of a trailing suction dredger with the movementand pumping characteristics of a cutter-suction dredger (e.g. horizontaland vertical position, no re-handling need, transport through a closed pipe-line). Of the two variants the scoop dredger is particularly suited for dred-ging contaminated materials, allows dredging in two opposite swingdirections, minimizes turbidity and dilution by water, and functions wellin depths from 3 to 28 m. With mining at depths that are considerably


greater, use of the dredge is thus limited. The sweep dredger is best suitedfor thin (0.2 to 0.6 m) silt layers removal in shallow depths (1.5 to 10m); ithas an adjustable cut height.

The Belgian Dredging International company developed mechanicaldredging techniques which it named respectively ecodrag, a bucket dredgeand ecograb, a grab dredge which reduces turbidity and spillage [8].

5. THE SEARCH FOR AGGREGATES

Severe regulations dealing with the quarrying of aggregates for building,paving roads, filling-in land, beach restoration and construction of artifi-cial islands are imposed on land, in most countries. These can be donewith materials with less stringent grain-size requirements than for con-crete. If there is still some lack of control on such mining in severalThird World countries, they too will need to rein in sand and gravel re-trieval. The search for alternate sources of construction materials has ledto exploitation of marine deposits [3, 8]. Texas roads and parking lots arefrequently constructed from shelly material. Dredging has intensified dur-ing the last decennia and controlling rules are difficult to enforce.

Of course, beaches and near-shore areas have long been tapped for sandand gravel. Many countries earn a considerable part of their income fromshore tourism, and unavoidably tourism and marine mining have comeinto conflict. A qui pro quo developed in that to maintain the beach inmany a location, artificial nourishment became necessary. But the materialto rebuild the beach is dredged, often, not far off-shore and such operationsoften pose environmental problems of their own. Beach protection and re-nourishment are antipodal to marine granulates mining and offshore dred-ging may trigger a faster rate of beach erosion.

Sea-level rise and exceptional storms have contributed to increased ero-sion and disturbed sedimentary budget and transit.

6. GEOGRAPHICAL DISTRIBUTION

A conservative estimate is that 70% of the world's continental shelves arehome to potentially mineable relict sediments. It is generally held thatmining those relict deposits may not adversely affect contemporary beaches

310 R. H. CHARLIER

located in-shore of mining (viz. dredging) areas. Muds, considered herethough not aggregates but still unconsolidated sediments, deposit wherecurrent speed is about 1!hknots, whereas sand are more common beyond1!h to 2 knots, and gravel accumulates, in depths of less than 50 m,where current speed ranges between 2 and 4 knots. Nevertheless near Mui-den (Netherlands) sands have been retrieved from depths exceeding 75 mbelow the sea level of Lake IJssel (remnant of the former Zuiderzee).A large amount of sea sand originates from continental run-off, gravellar-gely from glacial or fluvio-glacial transport. Gravels were used, along theNorthwestern United States and Canada coasts to build the artificial islandsneeded in gas and oil exploration (Fig. 2).

Exploration, and frequently exploitation, is carried out near Belgium,The Netherlands, France, Great Britain, Denmark, Sweden, Israel, Leba-non, Japan, the Laccadive Islands (Indian Ocean), and occasionally Thai-land and Hong Kong. France, Iceland and Fiji are first rank extractors ofshell material. Coral sand has been dredged offshore Hawaii, Fiji, Icelandand calcium carbonate was mined as lime shells on the Gulf and Pacificcoasts of the United States. Lime production from coral is an ancient arti-sanal occupation in Sri Lanka, but on Taiwan, pink coral is retrieved usinga two-man submersible!

The United Kingdom ranks first in marine aggregates mining. Like Japanit gets from the sea 20% of its sand and gravel need needs [9]. Togetherthey account for approximately the two-thirds of the world production.Though it is claimed that North Sea reserves could suffice for anotherhalf century, it appears that dredging and mining should be placed undermore stringent control if accelerated depletion is to be avoided [9]. Sandand gravel mining started in 1915 but commercial exploitation waslaunched in 1961. Already 35 years ago the combined mining of the UnitedKingdom, France, Denmark and The Netherlands had reached 50 millionmtfy, of which 16 million mt for Britain alone, from maximal depths of36 m. However to these amounts one must add British companies' illegalsand and gravel retrievals adding to several million tons per year.

The British production of 1810mtfy is marketed inland and partially ex-ported to Belgium, France, The Netherlands and Germany [10]. About 14%is used for concrete [10]. Belgium and The Netherlands (exceeding some-what one million mtfy), Denmark and Germany are modest-size producers.The shortage of construction material in Brittany boosted marine aggre-gates mining and sand bars, even mine tailings, have been tapped. In fifteen


years (1970-1985) some 18 million mt had been extracted. The Frenchgovernment had to step in and limited exploitation to deposits at maximaldepths of 25 to 30 m away from areas of hwnan occupance, fishing zones,biological breeding places, and navigation routes, viz. at 2.7 nautical miles(5 km) from the coast [11].

Deposits line the Atlantic United States coast from Maine to Florida.Large "producers" of sand are New York, Florida, Mississippi and onthe California coast [12]. Smaller production is carried out in Connecticut,New Jersey and Texas. In all but New York gravel is also retrieved. Nan-tucket Shoals, the Massachusetts coasts, Puerto Rico and the Virgin Islandshave considerable reserves. Virginia sands and placers could serve asa source of material for beach replenishment and alternate minerals for in-dustrial needs. Glaciers were the predominant agents that determined loca-tion and character of sand and gravel deposits from Nova Scotia to LongIsland (NY). Southwards large deposits of detrital meltwater were broughtby streams. In New York harbor itself mining was stopped, even thoughprofitable, due to popular opposition [13, 14].

Shells are recovered in Louisiana, Alabama, Texas, further north inMaryland and on the Pacific coast near San Francisco [15].

Looking at the reverse side of the medal, many mining operations, in theUnited States, have been conducted with a minimwn of environmentalguarantees, a dearth of regulations, and hardly any public knowledge. Itis difficult to believe, yet it is fact, that mining of the near-shore, foreshoreand dunes has been conducted in Monterey Bay since 1906 [16, 17].Operations were totally unregulated, until protests and litigation were in-itiated by environmental groups after oceanfront and shore retreat, dune da-mage of major proportions, and perhaps to largest shore erosion of SouthBay. Beach nourishment to stem it created a supplementary demand forsand [18].

Since 1995 over 2.75 million m3 of outer continental shelf sand resourceshave been used in the United States in five shore protection or restorationprojects, but this part of the shelf is increasingly eyed as a source for build-ing material. Mining of aggregates is thus of importance for beach mainte-nance, for hurricane protection and commercial use. This is currently thecase for the United States' Gulf of Mexico and Atlantic coasts whereknown continental shelf sand resources still need to be identified. Thecountry's Minerals and Mines Service provides guidance for the develop-ment of sand resources on the Outer Continental Shelf and, in cooperative

312 R. H. CHARLIER

programs with the individual States, it has developed a geological systemconcept as a framework to determine the suitability of deposits for develop-ment. The programs ought to give due consideration to the environmental,including especially sustainability, aspects of mining operations. And, in-deed some plans to grant leases, p.ex. off New Jersey, which ran into fierceopposition from environmental and tourism groups, were subsequentlyshelved. Opposition to marine mining of sand is common and widespreadin the United States: an amendment to the Outer Continental Shelf LandsAct (Public Law 103-426) found itself blocked by legal actions, and, yet,it sought merely to simplify the transfer of its sand and gravel resourcesadministration to State or Municipality for appropriate public uses, viz.shore protection and beach maintenance.

At the 1999 Offshore Technology Conference, Federal cooperative pro-grams with Alabama and Virginia were highlighted as models for assess-ment. The examples conform with the US Army Corps of Engineersregional sediment management approach designed for both coasts andrivers.

Beaches of the Hawaiian Islands are biogenic and there are no continen-tal shelves. The search for sands to be used in coastal protection schemeshas been directed offshore at ancient beaches now at depths of about 100meters. Recovery of such sands has been stymied for over two decadesby administrative complexity and opposing mandates. One may hope thatregardless of the offshore and deep water location of the sands, normallymitigating negative environmental impacts, operations and plans will bemonitored and controlled. The sands are often located at 100 to 150 mdepths seaward of contemporary reefs.

Related to mining operations is the concern for coral reefs systems, fre-quently defined as those species, habitats, and other natural resources as-sociated with coral reefs; in the United States they are protected,supposed to be restored and their sustainability is to be insured. A budgetof $17.2 million was set aside by the US government for those purposesfor fiscal year 2000, not counting $200 million for countering the effectsof water pollution on the reefs.

Sustainable use of coral reefs, parallel to any other natural resource, hasbeen described as a philosophy that considers the resources as a commu-nity's bank account, against which the interest can be drawn, as long asthe principal remains protected. In some island areas, particularly inmany "small" island States (e.g. those of the SIDS and AOSIS groups,


a.o. Nauru, Tuvalu, Marshall Islands) the only construction materials arereef-derived sands, reef rock, the reef itself; people were thus "forced" toturn to those sources of building materials; unfortunately such mininghas brought about irreversible damage, including shoreline modifications.The latter's protection with inshore sands impacts severely on the adjacentreef systems. Some relief may come from sands deposited in lagoons atmoderate depths or beyond the boundary reefs at the drowned beachesidentified for Hawaii but possibly Pacific wide. An environmental assess-ment off Fafa Island (Tonga) was carried out for Tonga Lagoon indicatingthat sand mining would not negatively influence tourism nor fisheries; thesource sites at less than 20 m depth would provide sand for 30 years at a costbelow $12/metric ton. To the contrary sites off Vavu'u (Northern Tonga)proved uneconomic. Mining the sands mentioned earlier at 30 to 100 mdepth apparently requires an investment exceeding the financial means ofthe small islands States. Kiribati's Tarawa Atoll's shallow water sand depos-its have been similarly assessed.

Beach restoration and coastal protection has become a major concern inthe Caribbean. There, as in the Pacific, deposits of sands offshore at depthsof 75 to 125m are hopefully free of coastline impacts. Recovery would bedone by use of large drag suction hopper dredges, and small deep diggingsuction dredges-using submersible pumps on the bottom, and adaptationsof the continuous line bucket system.

Across the Pacific, India proposed to mine sand at depths of 500 metersto stimulate a ferro-magnetic nodules recovery operation, which howeverare lying on the bottom at 5000 meters depth [19]. Undoubtedly lessonslearned from oil and gas recovery will be adapted to deep seabed mining.Coastal sands are, in fact, an issue that is not limited to a few locations butpose problems throughout Eastern Asia and are an acute problem for Viet-nam and the Maldives.

The cassiterite-sands have provided 6% of the world's tin production inSoutheast Asia [19, 17]. A Russian approach seems to be harmless to theenvironment, though former-Soviet claims ought to be taken with reserve[19]. Tin-bearing sands are located by a robot (equipped with camera, ma-nipulator, remote control sampler) and a tentacle equipped bottom crawlerrakes and sucks up sand. Drawn up through a hose the material is pro-cessed, the surplus sand being returned to refill a worked area. The claimthat the ecology is not disturbed must be tempered as the dredging opera-tion still is an ecologically disturbing activity. Dredging is furthermore done

314 R. H. CHARLIER

using nuclear-powered dredges. Cassiterite mining has been ongoing inRussian and former Soviet-republics waters in the Laptev, Arctic, Okhotsk,Baltic, Black and Japan seas.

Heavy minerals extracted ftom sands include rutile, zircon and ilmenite.Extraction areas are located, besides the coast of Australia, near Java andBali (Indonesia).

Production in Japan equals or surpasses that of the leader, the UnitedKingdom. Total number of dredges near 1000 removing at least as muchas 70 million mt/y. Statistically speaking the Japanese marine productionrepresents close to 25% of the total production, and 25% of the fine aggre-gates used in the manufacture of cement also is of marine origin [20]. Thebulk of the retrieval is conducted offshore Western Japan, 60% ftom SeitoIsland and 35% combined off the Kyushu north coast and the Shikokusouth coast.

Japan prides itself of having built several artificial islands by reclamationbut also to have developed the dredge-and-fill method. While it undoubt-edly has supported economic growth in the past decades making possiblethe construction of large industrial complexes along the coastline, littlehas been disclosed of the environmental impact of these fleurons of Japa-nese marine and coastal space utilization. An artificial island covering590 hectares has been recently constructed in the Seito Sea (Japan) at5 km ftom the mainland in water averaging 11m depth [21]. The operationcosting $10 billion accomodates Kaba international airport [21].

Summarizing, major commercial operations exploit deposits in the Uni-ted States, Canada, Japan, Thailand, Hong Kong, the United Kingdom, TheNetherlands and France, but granulates are also retrieved in and by Iceland,Sweden, Denmark, Israel, Lebanon, Morocco, the Republic of South Am-ca. Pacific Ocean island nations are badly in need of construction materialswith crucial demands ftom the Cook and Solomon islands, Samoa, Fiji,Guam, Tonga, Kiribati, Vanatu and Tuvalu [22].

7. ENVIRONMENTAL ASPECTS OF MARINE AGGREGATESEXTRACTION

If one is tempted to rejoice at the use of the oceanic domain to solve thesevere shortage of aggregates and the fewer sores caused by quarrying on


land, one should not overlook the environmental consequences on thecoastal "zone". Impacts result ftom the removal of sediments and ftomthe dredging operation itself. Mining of aggregates modified shorelines,river mouths, the distribution of living resources, marine currents and up-wellings and influences the climatic regime in the areas of extraction(Tab. III).

The physical impact of dredging includes discharges ftom hopperdredges and dumping overboard of tailings; these affect water quality,move and redistribute sediments, in short create an artificial sedimentaryprocess. Diamond mining operations along the coast of southern AtTica,e.g. Namibia, constitute one of the notorious examples. Dredging certainlydoes affect benthic life which is destroyed by crushing or being sucked-up.One may even envision the release of toxic gases and metals ftom under-neath the bottom's subsurface that would create health and survival pro-blems for animals and plants. Or nutrients being released may lead toeutrophic consequences. The release, ftom bottom sediments, of undis-solved metal sulfides leads to oxidation processes, formation of dissolva-ble sulfides and hydroxides, thereby lowering oxygen content of theambiant water, and potentially toxic effects ftom the released hydrogensulfide. Prohibition of operations in ftay and spawn zones are ftequentlyignored [23].

Hence, there is disturbance of marine organisms, there are problems ofsea-state modification, changes in flow patterns, currents shifting, interfer-ence with shipping lanes, with subsurface traffic, but also possible encoun-ters with stationary objects such as explosive ordnance, wrecks, oceanbottom structures, cables, pipelines and buoy-ed arrays.

From the biological viewpoint besides the direct physical damage toorganisms, the smothering of sessile life, after habitat removal there isafterwards, in case like cassiterite mining, habitat burial. Resuspensionof pollutants is an evident consequence. Scarratt makes a distinction be-tween dredging and mining (which he does not consider as damaging)but Oulasvirta and Lehtonen found that in years when 100,000 m3 of se-diments were removed in one site, the fish catch had substantially beenlowered [24]. Biota, examined in connection with sand dredging forbeach nourishment studies, is destroyed by the operations, and a newsubstratum, naturally available for colonization is created [24]. In Thai-land offshore mining on the southwest coast has virtually destroyed thefishing industry.

316 R. H. CHARLIER

Aesthetics and touristic-recreational consequences are nuisances witheconomic impacts. Source sites should be at substantial distance from bea-ches so that losses that these will encounter not originate sub-sea move-ments of sand towards the dredging site[s].

Isolated shoals are usually located below the wave-base and may com-monly be tapped without much impact on the shore-face sedimentary sys-tem. On the other hand sands retrievals near the coasts of Israel andLebanon caused considerable damage to the beaches and sand had to bedredged offshore to restore them.

The unavoidable water turbidity created by dredging interferes with thelife of filter feeders, reduces light penetration beneath the water surface,oxygen production, de-oxidizes sea water.

It has been argued that the impact of aggregates quarrying on land can befar greater than marine extraction and that construction materials areneeded by modem society. Then a choice must be made between tourismand habitat on one side, construction on the other, and coastline landwardmigration, including loss of some towns, must be accepted as a fact of life[25]. A thorough knowledge of the coastal zone sedimentary processes mayhelp mitigate the negative impact, but cannot stop the damage caused bytapping marine sources close to shore and by other factors. [26]

Coastal quarries are important nowadays in Norway and Scotland,particularly around its islands, which both offer large aggregates deposits,but extended exploitation has met with strong environmental opposi-tion.

Sand mining by Belgian companies provoked protests by fishermen and,some time ago, an inter-ministerial fight between Public Health and Eco-nomic Affairs. Nothing was done, however, because contracts had beensigned with operators.

Ever deeper operations have significant environmental consequences andwith normal operational depths easily reaching 100m, and airlift system al-lowing still deeper retrieval, they are due to worsen [27, 28]

Technical progress does improve capabilities and may limit "errors" inenvironmental impact assessment.

A GIS designed to facilitate surveys of environmental data acquisitionand retrieving, pre-processing, visualizing geo-referenced informationfrom oceanographic cruises in the Bay of Naples (Italy)could be used to de-termine suitability, and sustainability of sand mining in close to coast sites.[29]


8. MARINE SANDS FROM THE GOLD COAST (AUSTRALIA)

Mining of sea sand deposits for their heavy minerals contents has beenmentioned earlier. Australia is no exception in the search for new sourcesof aggregates to satisfy the unquenchable need for construction materials.The Gold Coast area, a tourism and residential mecca on the southeastcoast, is lined offshore by valuable aggregate deposits at relatively shallowdepths. These have understandably been eyed for exploitation and an envir-onmental report submitted. An analysis of this voluminous document hasbeen conducted and reached the following conclusions in an ad hoc report.

9. CASE STUDY: AGGREGATES EXTRACTION OFF SYDNEY,NEW SOUTH WALES, AUSTRALIA

When retrieval of aggregates off the coast of New South Wales was pro-posed an environmental impact statement was prepared by an Australianfirm which produced a voluminous report. The impression however wasgathered that the report was slanted to support the project rather than a neu-tral analysis. Australia has still important land sources of construction ma-terials and the plan to tap offshore resources is based on economicconsiderations and the desire to reduce the distance between constructionsite[s] and source[s].

The company that solicited the E.I.S. asserted that its supply sources forconstruction materials were "drying up" and in its search for new onesmarine sites seemed the most suitable and environmentally benefic: movingover the life of the project 100 Mt aggregates by ship would suppress theroad transport associated nuisances of noise, dust, and congestion. The as-sumption that "nature" would replace, viz. replenish, the source site withsuch a quantity of material over a 50-year span is at best a risky one.The operation far more probably would result in an outright submarinemorphology modification and it would take-as the report recognizes-thousands of years to flatten the ridges at the edges of the excavation.

A 20 to 25% thickness would be removed from a 25 to 50 m thick sandlayer over a period of 50 years. This would consistently eliminate a largesegment of flora and fauna as the upper 0.2% of the sand layer is a biologi-cally quite "active" zone. Discharge plumes, whether visible or not, wouldaffect filterers. Destruction of the upper sediment layers and generation of

318 R. H. CHARLIER

turbidity plumes have negative biological impact; habitat removal is fol-lowed by habitat burial and re-suspended pollutants may harm organisms.Skimming or beheading of banks, as proposed in the Sydney project, nega-tively impacts local marine eco-complexes, though effects may be mini-mized if excavation areas are of limited size.

The proposed dredging sites are commonly at less than 1km and at most2 km distance from shore; specifically this is the situation foreseen at Pro-vidential Head, and the distance varies from 3/4 to 2 km at Cape Banks. Im-pact of sand removal would most probably affect Botany Bay, and its outletto the sea. Dredging in the United Kingdom at 0.6 km from shore has beenseverely criticized, disastrous consequences experienced on the Lebaneseand Israeli coasts, and a distance of at least 3 nautical miles recommendedfor exploitation of the Flemish Banks (North Sea). The E.I.S. suggesteddredging in waters whose depth exceed 50 m. These measurements are incontradiction with the severe norms set by the French for such operations:these set distance from shore to edge of retrieval area at minimum 212nau-tical miles, depths not exceeding 25 to 30 m and sites "away" from inhab-ited, recreational, fishing and biological breeding zones. Belgiumadditionally limits operation to the use of hopper dredges with dragged con-duits. This to the end of minimizing bottom topography modifications,shoreline shifting and increased beach erosion.

If specific constraints set for operations off Sydney were to be respected,the euphoric assertion that where extraction would be permitted it could bedone safely at depths exceeding 30 m, is improbably not as unanimous aspictured. Re-colonization of extraction areas in as little as three monthstime appears an unusually short period. No scientific data supporting theaccuracy or even "realism" of such projections was furnished in the docu-ment. Most cases discussed in the literature make estimates in terms ofyears. Even if only 2% of the water layers above the seabed would be af-fected by operations, benthic life would be nonnegligibly disturbed. It isprobable, however, that by leaving, as the permit seekers planned, undis-turbed areas between dredging tracts, repopulation zones are createdwhich would speed up the recolonization process.

Botany Bay is a beach that accretes (30,000 m3 in 27 years, and a 20 mseaward migration of the shoreline). There would thus be no damage result-ing from sand extraction, but the study nevertheless shows that it wouldhave a localized effect on currents, without changing their general structure,nor influencing the Botany Bay entrance tidal current. However, sand


transport rates would be reduced and slow filling-in of areas through flatten-ing out of batter slopes would occur.

Looking over the proposal, an independent observer may conclude thatthere is a serious lack of sociological assessment and be surprised thatthe overwhelming negative consequences are economic: shareholders of acompany would miss an opportunity to collect substantial returns, investorswould be shaken up, sand would be more costly, and the State governmentmight have to forsake US$IOO million in revenue over the life of the pro-ject, or US$2 million per year. In times of budgets running into the billionsand trillions of dollars, this does not seem a significant amount.

10. OUTLOOK

The search for sand and gravel continues and as most minerals take cur-rently somewhat of a back seat, particularly, some years ago, consideringdiamantiferous deposits, aggregates are on the front burner. The newdrag suction hopper dredges can operate at depths exceeding 100 m andhave been put at work for large coastal construction works in southeastAsia. The interest is keen for supplies of materials for coastal maintenanceand beach restoration resulting in the survey of potential aggregates depos-its in waters 100 to 500 m deep.

It was predicted that near-shore aggregates, natural hydrates and deepseabed sulfides would be the most important focus of marine mineralsexploration, and exploitation, in 2001.

11. CONCLUSION

The tapping of the marine resources of aggregates, taking into considera-tions land resources depletion and environmental constraints, will be con-tinued, is not only an unavoidable development, its intensity is due toincrease [30]. Therefore it is imperious that extraction be sternly regulatedand that retrieval practices be environmentally sound and in line with sus-tainability considerations [31]. In some instances, specifically coral reefs,avoidance of using the material should be enforced whenever and whereverpossible; this requires more than pious international alarm moans, it neces-sitates decisive national policy [32, 33].

320 R. H. CHARLIER

The menace to the marine environment in general, as greater depthsbecome accessible to the dredgers, yet at present still particularly the rela-tively near-shore areas, is such that UNESCO set up a "Forum" alreadylinking, according to E. Troost, some 6,000 persons. It is accessible onthe internet at moderator [34]. A paper by V. Cazes-Duvat ("A programfor the control of beach erosion in the Seychelles") on the Forum, datedJuly 3, 2001, generated considerable reaction; it can be accessed throughcsiwisepractices [34]. The US Mineral Management Services and the USGeological Survey stressed recently (2001) in reports that topologicalchanges in the seabed slopes and downstream (downcurrent) erosion onthe adjoining coasts had been observed; they result from offshore sandmining to retrieve material for beach nourishment. Serious impacts fromwave energy have been recorded during severe storms. An alarm cryfrom State authorities in Florida has warned during April and May 2001that "we are out of sand". These observations have led some at the FirstInternational Soft Shore Protection Conference-held in Greece in October2000-to oppose artificial beach nourishment works, maintaining that"dredging to nourish is not sustainable" [35].

Placing this matter in the context of the European Union's-slow--effortsto develop a strategy for a highly needed integrated management of theUnion's coastal zone it might be indicated to look at the US CZMA (CoastalZone Management Act}-already implemented several decades ago andperiodically adapted-as a basis for a potential "Directive". However, over-all aims, objectives, implementation policies should take into considerationthe multi-diversity of the European Union and any framework, and norms,should be sufficiently flexible.

References

[1] J.A. Oehais and M.A. Wallace, "Economic aspects of offshore sand and gravel mining",

Marine Mining 6(3), 245-252 (1988); US Congress. Office of Technology Assessment,Marine Minerals Exploitation. Our New Ocean Frontier (US Government Printing Office,Washington, 1987).

[2] R.H. Charlier, "Marine mineral resources extraction in coastal areas and its impact on the

environment, and consequences for land-use", In: Mineral Resources Extraction, Environ-mental Protection and Land-use Planning in the Industrial and Developing Countries(edited by P. Arndt and G.W Liittig) (E. Scheitzerbartsche Verlagsbuchhandlung, Stuttgart,1987) pp. 53-70; I.W Morley, Black Sand: A History of the Mineral Sand Industry inEastern Australia (University of Queensland Press, St Lucia, 1981).

[3] J.M. Padan, "Offshore sand and gravel mining", 15th Offshore Technology Con! Proc.(1988) 1, pp. 437-444.


[4] RH. Charlier, "Non-living resources", Ocean Yearbook VI (University of Chicago Press,1990) pp. 98-144.

[5] D.J. Harrison, "The marine sand and gravel resources off the Humber", British Geological

Survey (London, Technical Report WB/92/1, 1992).[6] WC. Penfield, "The oldest periodic beach nourishment project", Shore and Beach 26(1),9-

15 (1960).[7] RH. Charlier and C.P. De Meyer, "Artificial islands", Int. J. Envir. Studies 40(4), 244-265

(1992).[8] cf Sea Technology 20, 12-29 (December, 1977); re Japan: Sea Technology 38(4), 51 (April,

1997).[9] id., reference 4.

[10] J.M. Uren, "The marine sand and gravel industry of the United States", Mar. Min. 7(1-2),

69-85 (1988).[11] R.H. Charlier, M.C.P. Chaineux and c.c.P. Charlier Keating, "Impacts of aggregates

mining on the coastal zone", 3rd Int. Symp. Environ. Geochem. In Tropic. Countries-Bookof Abstr. [Novo Friburgo RJ Brazil] (full text on CD-Rom) (1999) pp. 101-102.

[12] P.T. Tweedt, Summary of Ocean Mining Activity and Related Research (Nat. Ocean &Atmosph. Administr., Washington DC, 1985).

[13] WL. Stubblefield and D.R Duane, "Processes producing North America's east coast sand

and gravel resources: A review", Mar. Min. 7(2),89-122 (1988).[14] RE. Bowen and M.A. Cucci, "Finding reservoir sand in deep gulf of Mexico waters",

Ocean Ind. 22(1), 11-13 (1987).[15] G.D. Goeke, "Oyster shell dredging in Atchafalaya Bay and adjacent West Louisiana",

Draft Environmental Impact Statement and Applications (Army Engineering District, NewOrleans LA, 1987).

[16] S.J. Williams, "Sand and gravel deposits within the US EEZ: Resource assessment and

uses", Proc. 18th Ann. Offshore Technol. Conf (1986) 18(2), pp. 377-386; WM. Wise andD.B. Duane, "An introduction to the sand and gravel workshop", Mar. Min. 7(1-2), 1-6(1988).

[17] J. McGrawth, "Sand mining in Monterey Bay: An update", Proc. Coastal Zone '89. (ASCE)(1988)pp.512-524.

[18] Bowen and Cucci, cf, reference 14.[19] R.M. Linebaugh, "Ocean mining in the Soviet Union", Mar. Techn. J. 14(1), 20-24

(1980); T. Packer, Survey of Foreign Development Activities for Offshore Non-fuel MineralResources (Government of Canada, Department of Energy, Mines and Resources, Ottawa,1988).

[20] K. Tsurusaki, et al., "Seabed sand mining in Japan", Mar. Min. 7(1-2),49-68 (1988).[21] Anonymous, "International seabed authority", Sea Technology 38(4), 135 (April, 1997).[22] M. McCloy, "South Pacific islands heal sand shortage", The A.A.P.G. Explorer 5(13), 16-

18 (1984).[23] E.C. Pirlcle, "The yules heavy mineral sands deposits of North Carolina and Florida",

Economic Geology & Bull. Soc. ofEcon. Geol. 79,725-737 (1984).[24] if, references 11 and 20.[25] T. Sheppard, The Lost Towns of the Yorkshire Coast (A. Brown and Sons, London, 1912);

R.H. Charlier, P.Bruun, M.-C.P. Chaineux and S. Morcos, "Historical perspective on coastalprotection", Proc. Int. Congr. Hist. Oceanogr. VI (Beijing. PRC, 1998) [2002, in press].

[26] B.J. Cuiliton, "Save the beach, not the buildings", Nature 357, 535-541 (1992).[27] cf, reference 11.[28] cf, reference 11.[29] M. De Lauro, G. Giunta and R. Montella, "Marine geographical information system

development: Mapping the Bay of Naples", Sea Technology 40(6),53-59 (1999).[30] RH. Charlier, RL. Gordon and J. Gordon, Ocean Resources. Economic Oceanography

(University Press of America, Washington DC, 1980); R.H. Charlier, "Non-livingresources", Ocean Yearbook I (Univ. of Chicago Press, Chicago, 1978) pp. 96-134.

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[3 I] E.M. Borgese, The Mines of Neptune (Abrams, New York, 1985).[32] cf, reference 2 I.[33] R.H. Charlier and c.P. De Meyer, Coastal Erosion: Response and Management (Springer

Verlag, Heidelberg-Berlin-New York, 1998); R. Charlier, E. Blomme, C. Clayes, F.Fettbein, et al., Kursus Pentai (Technological Institute, Bandung-Indonesia, 1991)

[34] cf, [email protected]; http://www.csiwisepractices.org/?read = 357.[35] Proceedings of this conference can be found at internet site http: //communities,msn. com.!

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