25 Years Dredged Material Policy in Hamburg

8/3/2019 25 Years Dredged Material Policy in Hamburg

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25 years dredged material policy in Hamburg

A. Netzband1, and G. Werner2

Abstract: For hundreds of years dredging has taken place in the Port of Hamburg to maintain water depths. In

the second half of the last century, the contamination of sediments in the Elbe at times reached very high

levels, particularly as a result of inadequate effluent treatment in former Eastern Europe. Until German

reunification in 1989, Hamburg knew little about the causes of contamination in the dredged material from the

Elbe, let alone had the opportunity to influence policy and eradicate these.

Against this background Hamburg has developed and implemented a highly technical dredged material

management concept. Today, the disposal of dredged material is multi-faceted, with relocation in the river

being the most important solution. There is still around 1 million m3of dredged material to be handled onland at great expense; further details of this are included in the contribution by (Detzner and Knies, 2004).

Although 25 years ago public discussions also contributed to the development of this policy, today legal

requirements create a narrow framework. The requirements are frequently those of the European Union. The

Water Framework Directive may present a framework for solving the remaining problems of contamination.To ensure that dredged material can be handled properly in the future as well, joint efforts by those

responsible for ports and waterways are necessary.

Keywords: dredged material, Hamburg, treatment, beneficial use, confined disposal, relocation

1 Behrde fr Wirtschaft und Arbeit / Strom- und Hafenbau, 20457 Hamburg, Dalmannstrasse 1,

Tel.: ++49 - (0)40 - 428 47 2791, Email: [email protected]

2Behrde fr Wirtschaft und Arbeit / Strom- und Hafenbau, 20457 Hamburg, Dalmannstrasse 1,Tel.: ++49 - (0)40 - 428 47 2411, Email: [email protected]
mailto:[email protected]:[email protected]:[email protected]:[email protected]


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1. HISTORICAL DEVELOPMENT

The history of the Port of Hamburg goes back over 800 years. As long ago as 1189 the city was granted the

right to bring ships containing goods for Hamburg into the city without customs duties. Today Hamburg is

one of the worlds top 10 container ports.

The port lies around 100 km from the North Sea, far inland on the Elbe. The tidal current is strong for thisarea. To make shipping possible and maintain sufficient depth of navigable water, it has always been

necessary to dredge the river. We know that around 1530 there was a decree prohibiting the excavation of

sand at certain points, and also the disposal of refuse and other materials. A control commission existed to

monitor this. In 1860 the depth of the navigation channel was around 4.50 m, today it is 14.50 m.

Even before the industrial revolution, simple manually-operated dredging equipment such as silt collectors or

sand wheels were in use. The Hamburg Rotating Lighter (around 1800) can be seen as the forerunner of theHopper Dredger and could dredge approx. 16 m3/day. In 1834 Hamburg imported the first mechanical chain-

and-bucket dredger from England. The next significant progress in dredging technology was the development

of hydraulic transport of mixtures of water and solids in pipelines; this led in around 1900 to the use of hopper

suction dredgers.

Fig. 1: Steam dredger in 1877

Disposal of the dredged material had in earlier times posed no particular problem for the port and water

authorities. Basically there were two options:

Replacing (relocation) in waterways in places where this did not hinder ships navigation or was plannedas part of constructing water courses e.g. in building side channels, groyns etc.

Disposal on land: the dredged material could be used to raise low-lying areas. In the ports on the NorthSea coast, for example, dredged material was used in large areas to extend ports, for industrial

developments etc. The nutrient-rich silt was often spread on agricultural land to improve the soil.

In disposal on land, progress was made gradually over time. In the Port of Hamburg, the dredger barges had to

be emptied by push carts for decades. Engineers later developed an overhead track system and barge loaders.

Finally, around 1900, barge suction devices started to be used which could pump the dredged material over

large distances and dump it in previously diked so called flushing areas. This meant that a very economic

option had been found.

As a result of the expansion of the port, the Elbe has changed its appearance substantially in the Hamburg

region over the past 200 years. Previously the river had been characterised by many main branches and

tributaries which formed lots of large and small islands. The growing port made it necessary for these to be

connected, for landing bays and transshipment areas to be created and for new inner harbours to be

constructed. The dredged material produced in making the harbour deeper was always used to create new

surfaces or raise levels. This meant that material produced during maintenance work was also disposed of atthe same time.


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For more than fifty years, development work in the twentieth century was therefore characterised for the most

part by technological advance and the scope of work undertaken also grew with the new technical

possibilities. However, in recent decades completely different requirements have come to the fore.

2. THE ELBE AND ITS CATCHMENT AREA

Hamburg lies on the Elbe, one of the great European rivers. The river is 1,091 km long and has a catchment

area of 148,000 km2, in which 24.7 million people live. All the major industrial regions of the former German

Democratic Republic (GDR) including the Berlin metropolis and the majority of the Czech Republic lie

within the Elbe region.

The Ore Mountains (Erzgebirge) lie within the German Elbe region, and minerals have been mined and

processed here since the Middle Ages. The rock material was placed on dumps from which metals were

continuously leached. Tanneries and paper manufacture in Bohemia led from the 14th century onwards tosubstantial contamination of the water. After the First World War, large industrial enterprises grew up near

the coal deposits in the Halle/Leipzig area. Constructing and operating these businesses, particularly in

wartime and under the conditions after the war created environmental pollution, and effluent flowed largely

untreated into the rivers.

Efforts were made in the GDR to reduce this environmental burden, but these remained far behind western

standards. In 1989, domestic effluent treatment was only partially available in the GDR and often only as

mechanical treatment. Industrial effluent treatment, when available at all, was inadequate. Highly toxic waste

was partly dumped directly into waterways.

Fig. 2

Fig. 2: Arsenic content in the drilling core of an alluvial soil from a floodplain area from the Bucher Brack

at Tangermnde (from Prange et al., 1997)

shows the development over time of arsenic contamination in the drilling core of an alluvial soil some

100 km upstream Hamburg. The worst contamination is clearly seen around 1970 and is at least 10 times the

background value.

concentration (mg/kg)

depth (cm)

Until 9th November 1989 only the level of contamination in the Elbe water in Schnackenburg on the former

German-German border could be measured; nothing was known of its origin. Although the polluter pays

principle was also applied in the GDR, in effect a user principle was applied, i.e. whoever wanted to use clean

river water should pay for it. Even before reunification, there were German-German talks on environmental

protection, although at the request of the GDR nothing was to be made public about the results of these and,

as far as the Elbe was concerned, no results worth mentioning were achieved. One exception was a pilot plant

for eliminating mercury during chlor-alkali electrolysis in the Bitterfeld chemical compound which succeeded

in halving the mercury content even before 1989.

After the Berlin wall came down, the situation changed dramatically. Even shortly after reunification, there

was a significant reduction in contaminants discharged in the river because of the collapse of whole industrialsectors. From time to time, however, an increase was also recorded, which was probably caused at least in

part by clearance work.


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In May 1990 a joint German-German survey trip on the Elbe was undertaken. The first international

agreement signed by the reunified Germany was the agreement to form the International Commission for the

Protection of the Elbe (IKSE). In the 1990s the Elbe was intensively investigated and today we are well aware

of which contaminant comes from where. Fig. 3 shows mercury contamination in suspended matter in 1993.

The substantial increase in contamination as a result of discharge by the Czech company Spol-Chemie via the

river Bilina becomes clear. This substantial contamination only reduces slowly along the river in the direction

of the North Sea. For current developments, see Fig. 7.

Fig. 3: Concentration of mercury in suspended matter in a longitudinal section sample taken from the Elbe in

1993 (source on right, Elbe mouth on left. Grenze is the German-Czech border. (Diagram by GKSS)

In the early 1990s, the IKSE initiated a series of programmes with the aim of cleaning up in particular the

main industrial complexes such as the chemical, pharmaceutical, paper and leather industries. In the period

from 1990 1999 181 local water treatment plants were built from new, extended or reconstructed inGermany and the Czech Republic for a total equivalent population of over 21 million. Investment of 3 billion

or 12.1 billion Czech Krones was required. The North Sea saw its ammonia contamination from the Elbe

reduced by 62 % compared with 1990. Due to the efforts made by industry, between 1994 and 1999 loads for

significant parameters were reduced between 50% and over 90%.

Major challenges still exist today, however, such as abandoned mines, brownfield areas etc, which represent a

hazard to soil and ground water, as well as to the Elbe. Sums of many billion Euros would be needed to clean

these up. There is also an increasing amount of indirect contamination.

3. REALISING SEDIMENT CONTAMINATION IN THE PORT OF HAMBURG

The major contamination in the Elbe and its sediments was recognised in the 1970s as a result of various

different investigations (like Frstner and Mller, 1974; Lichtfuss, 1977). The whole harbour area was

examined in 1978/1979 for the first time to ascertain the level of contaminants in the sediment.

The trigger for these investigations was not least the very active environmental movement which arose during

the 1970s in Germany, concentrating in Hamburg mostly on water-related topics. In addition to the drinking

water supply and municipal wastewater treatment, sediment contamination in the vicinity of a copper mill in

the port and the conventional dredged material land disposal were a focus for activists. The environmental

groups carried out their own surveys and accused the Senate, the state government, of inadequate action.

Mention of the problems caused from upstream was met with anger about the problems caused locally. The

disposal operation was hindered by protests (Fig. 4).


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Fig. 4: Demonstrations against the land disposal operation in 1982

At the start of the 1980s the level of a total surface area of over 2,000 hectares was raised with dredged

material and approx. 400 hectares of the receiving surfaces were used for agricultural purposes. Since the

problems of heavy metals became known, the soil used for agriculture has been examined for its content of

various heavy metals using agricultural crops grown there. It has been found, for instance, that cadmium

levels are above the standards. The farmers affected were recommended as far as possible to avoid growing

wheat and oats and only to plant animal feed crops.

The conventional disposal operation led to contamination of the ground water with contaminants washed out

with the dredged material. With relatively uncontrolled washing, classification by sand and fine-grain silt was

introduced; the sand layers work like drainage through which the contaminated water can seep into the groundwater. At the same time in the existing disposal areas there was only very limited disposal capacity which

made it necessary for new areas to be added.

Similar problems were known about in other ports e.g. Rotterdam and the USA. The consequences in

Hamburg were great public pressure to find new solutions, without of course the opportunity of tackling theproblem of contamination at its sources.

4. DREDGED MATERIAL RESEARCH PROGRAMME

The development of the Hamburg dredged material policy must be seen against this background. In 1981 the

Hamburg Senate, the regional government, voted for a dredged material research programme to examine the

possibilities of recycling or disposal the dredged material, the causes of sedimentation and contamination and

to look for new disposal sites. The first results in 1983 indicated that

sedimentation in the harbour basin is natural and cannot really be influenced the burden of contamination comes largely from upstream, but also from sources in Hamburg the contaminants are attached relatively firmly to the fine grain fraction cleaning the silt of contaminants is not possible with best available technology recycling the dredged material as a building material is desirable but not yet possible after dewatering, silt is a cohesive earthwork material by separating sand and silt the problem can be reduced disposal in pits above ground or also underwater should be examinedIt was further decided that new areas should be found for disposal in Hamburg, that the disposal practices

used previously had environmental risks and that further, more in-depth investigations were necessary. It was

very soon apparent that for further treatment, separation into sand and silt is not only necessary but also

sensible for quantity reduction. The ideal of solving the contamination problem by some sort of

decontamination process persisted in parts of the general population through to the 1990s.


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5. METHODS OF HANDLING DREDGED MATERIAL IN THE 1980S

With the new developments, in many respects new ground was broken, of which there was little experience

elsewhere either. Taking into account the Iron Curtain, it had to be assumed that the level of contamination in

the dredged material would be high for a long time, so solutions were to be sought for a period of about 25

years. Possible ways of reducing the amount of sediment were soon discovered, but can only be used in parts

of the harbour. Open water disposal was at that time not a real option.

The first possibility was modifying existing disposal sites, i.e. in particular to avoid seepage into the ground

water. To reduce the quantity of dredged material to be confined disposed it is necessary to separate the sand.

The longitudinal flow separation in large basins was developed for this. For a technical description of the

solutions set out below, see contribution by (Detzner and Knies, 2004).

Fig. 5: Pilot plant METHA I in the Port of Hamburg 1987

Existing flushing fields were used for these installations, although this had the disadvantage of requiring large

surface areas and being dependent on the weather during the drying process. As the intention from the outset

was also to reclaim the dredged material or possibly even further separate off contaminants, the possibility of

mechanical handling of dredged material was investigated; first on a laboratory scale at the University, thenon a pontoon near the dredged material handling unit (METHA I). After the underlying questions had been

clarified, the decision was taken in 1990 to build a major technical installation.

Since then there have been constant suggestions as to how the dredged material could be disposed of even

more effectively, e.g. by freighting to Africa and greening the desert by making the high nutrient content of

the silt usable. The only realistic possibilities were, however, thermal treatment or reclamation as ground infill

material.

Fig. 6: Francop disposal site 1986 before the mound was built


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Existing flushing fields were used for disposal of the treated dredged material. This has two advantages: no

new areas had to be used and by modifying the old areas and covering these with the treated silt, seepage into

the ground water was minimised, i.e. the area was reclaimed. However, disposal the silt in mounds almost 40

m high also posed new technological challenges: would this be a safe long-term solution and what

requirements in terms of soil mechanics should be placed on the infill material?

Work on constructing the first mound in Francop was started in 1991 and the mound was equipped with large

edge support structures. The second mound in Hamburg, which received planning permission in 1998, no

longer has these edge supports as experience had shown that they were not essential. At the start of the

development about 20 years ago there were practically no general technical requirements on building disposal

sites, but when the second mound was constructed detailed German and European legal requirements had to

be taken into account. A further problem was that these did not take the special characteristics of dredged

material into account which mean that if it is properly handled it has high water density and therefore can be

both disposed as waste and beneficially used as a sealing material.

6. THE SEARCH FOR FURTHER DISPOSAL SITES

As one of the largest ports in the world the Port of Hamburg has major economic importance well beyond the

city boundaries for the whole region. Around 140,000 jobs depend directly and indirectly on this economic

fact. Both neighbouring German states have recognised the significance of this and have given politicalagreement since the mid 1980s to making areas available for disposal the dredged material.

First the northern state of Schleswig-Holstein proposed 6 potentially suitable areas which were all close to

waterways, because of the need to transport the dredged material handled in the Hamburg METHA, althoughsome of these were over 100 km from Hamburg. This search for disposal grounds caused considerable

disquiet in the population who felt threatened by poisonous silt. This went so far that agricultural companies

declared that they would not purchase agricultural products from an area surrounding a dredged material

disposal site because it was feared that crops would be contaminated by blown over silt. These fears were not

alleviated by the results of large-scale dust measurements carried out in the area around the Hamburg mound

in Francop which is located directly next to fruit plantations. Using suitable building methods ensures thatdrifting is kept to a minimum.

The southern state of Lower Saxony took a different approach. Politicians set up a conciliation procedure to

find a solution. Interested groups ranging from agriculture to environmental pressure groups organised theprocedure which was arbitrated by a self-elected Moderator, the Chancellor of a University. The aim was to

work out a set of recommendations for the regional government of Lower Saxony. Several events were

organised at which all the important aspects were discussed. The Hamburg authorities were allowed to attend

these but had no voting rights although they paid for the Elbe Silt Forum. After a year of what were

sometimes intense discussions, the recommendations were presented in autumn 1994 (summarised below):

Avoiding input of contaminants into the Elbe (source control) is the only way of permanently alleviatingthe dredged material problems in Hamburg and cleaning up the Elbe must have absolute priority.

Setting up an Elbe cleaning fund and accelerating measures for cleaning work including the latesttechnology for effluent treatment, reducing diffused inputs, measures to prevent soil erosion, covering

and/or cleaning up tips, leaving and immobilising deeply consolidated sediments with a contamination,removing or cleaning highly contaminated sediments in an environmentally friendly way from dammed

areas, groins and dike foreshores only if it is not possible to leave these in the Elbe.

Dredged material in the area above Hamburg should only be disposed elsewhere if the contamination isless than that in Hamburg and otherwise should be treated on land if sustainable relocation in the river is

not possible.

The experts appointed have ascertained that currently there is no single technical solution for recyclingthe dredged material which would in the short term alleviate the need for disposal. More physical sorting

procedures and thermal treatment should be investigated. As long as the contamination remains and sustainable relocation in the waterway system is not adequate,

there must be a guarantee that the silt is safely disposed elsewhere. The Hamburg plan for mound

disposal is not seen as suitable. As a temporary measure, the salt caverns near the Elbe should be filled. The Elbe Silt Forum showed that comprehensively involving the population in the search for solutions to

political problems very quickly produces creative ideas not previously thought possible.


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Some recommendations, such as the primary requirement of cleaning up the Elbe, acknowledge Hamburgs

position. It was recognised that reclaiming large quantities is not really possible or affordable. The proposal

which then came to the forefront in further discussions for filling in excavated salt caverns was, however,

shown in subsequent years not to be feasible.

The recommendations show that the previously very heated discussions have become more fact-based and

Hamburgs dredged material policy has to a certain extent been recognised. In the final analysis, however, the

problem of disposal of dredged material has not been solved.

7. FURTHER DEVELOPMENTS IN HAMBURG

In the mid 1990s the condition of the Elbe improved substantially, the reason being the measures taken after

reunification and the closure of whole industrial sectors. The knock-on effect was also a decrease in the

contamination in the dredged material from the Port of Hamburg. Fig. 7 shows this development using theexample of mercury which in the mid 1980s was still 100 times above natural levels in the Elbe and at that

time was seen as one of the major problems.

Fig. 7: Mercury contamination of suspended particles at the measurement point on the former German-

German border (from ARGE Elbe)

Since reunification it has been Hamburgs aim to reduce the contamination in the Elbe at source. In view of

the enormous problems in East Germany and the Czech Republic resulting from the new social and economic

order, political pressure to reduce the disposal of contaminants in the river would have had little success. The

city has therefore supported targeted clean-up measures. Great success could and has been achieved withsmall resources. Since 1997, for instance, Hamburg has supported the construction of two sedimentation

basins at the Czech firm Spol Chemie in Usti with financial aid of 150,000 Euros. This action succeeded inreducing mercury levels discharged into the river Bilina, a tributary of the Elbe, from 1.7 tonnes to approx 0.8

tonnes per year. Total mercury contamination in the Elbe was 3.1 tonnes in 1995.

In the mid 1990s the Environmental Ministers for the German states on the Elbe voted on Handling pollutedsediments on the Elbe. As a result of this, dredged material is, where possible, to be left in the waterways and

if it is contaminated, the first priority is to clean up the causes of this; the aim of protecting the sea must be

taken into consideration even in the upstream part of the river. This decision was tied in with the Plan of

Action of the International Commission for the Protection of the Elbe IKSE. As a transition measure, criteria

were defined for assessing dredged material for relocation.

Against the background of an improved overall situation, considerations were given in Hamburg to open

water disposal of dredged material with lower levels of contamination, as occurs worldwide in most ports andwaterways. Since the mid 1980s, agitation dredging with and without the use of compressed air has been used


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in individual cases as interim solution. In view of the negative ecological effect, this was, however, soon

replaced by the water injection dredging.

From 1994 onwards major tests were carried out on disposal in the Elbe downstream of the Hamburg port and

accompanied by comprehensive investigations. In this area low oxygen contents occur in the river during

warm weather, and there are fish growth areas close by. A particularly important point was therefore taking

measurements on the spread of the dumped material in the water column and drifting with the tidal flow

(effect of the tides), oxygen consumption and the effects on local biology. The investigations continued over

several years, and included investigations into various technologies and points for bringing in the dredged

materials relative to a cross-section of the river.

Fig. 8: Hopper dredger in use on the Elbe

The experience gathered was compiled jointly with the environmental authorities and resulted in a policydocument. This clarifies both questions of assessment of the dredged material and mitigation measures for

open water disposal, which for example would not take place in warm seasons. These agreements were

reached under a regional government in which the Green party was represented, which only 10 years

previously had been known for its opposition to the disposal of dredged material.

8. SITUATION AND OUTLOOK

Today the Hamburg dredging policy is multi-faceted. Maintenance of the port results in annual quantities of

approx. 3 to 4 million m3 of dredged material. A good 1 million m3 are treated on land, the remaining

quantity is relocated in the river. Of the land quantity, the major part is treated in the METHA plant, in

addition de-watering fields are operated as previously. The treated silt is either beneficially used or disposedin the Hamburg silt mounds.

Of course, all this comes at a price: just disposal of the dredged material alone requires expenditure from

Hamburgs public purse of the order of 30 million Euros every year without including personnel costs in this.

In total over 500 million Euros have been spent in the past 20 years. In the long term, this is not sustainable

for the city. Almost a third of the heavy metal contamination which reaches Hamburg from upstream is

removed with the dredged material for disposal on land, although, as the mercury example quoted shows, a

much greater effect would possibly be achieved upstream at less cost. It particularly begs the question as to

why a port should have to pay for the misdemeanours of its upstream neighbours.

The city has to a large extent done its job. In the municipal waste water treatment plants further cleaning

stages have been added and in industry also comprehensive efforts have been made. Public debate has over

the past 20 years become comparatively fact-based and less heated. However, dredged material can still

quickly become a hot topic again, as the Europe-wide debate about TBT in anti-fouling paints a few years agodemonstrated. In the Port of Hamburg the sediments with the highest TBT contamination levels are located


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particularly around the shipyards. These contaminated sediments are treated on land and the environment

agency is working with the shipyards to take steps to reduce emissions.

The situation today is fundamentally different to that of 20 years ago. Whereas in 1984 only a few boundary

conditions provided a legal framework for handling dredged material, there was at that time strong public

protest. These have today taken a more realistic approach, even if the Not in my Backyard syndrome

appears again everywhere when the search is on for new disposal grounds.

However, more and more legal requirements now govern the handling of dredged material, particularly when

it is disposed on land. The basis for these regulations is often European, for instance the German Recycling

and Waste Law is the incorporation of the European Waste Law, and the German Landfill Regulations

implement the European Landfill Guidelines. The beneficial use of mineral waste is regulated nationally, as is

soil protection.

Although the aim is to beneficially use waste and dredged material is waste in a legal sense when it is

brought onto land it has to be recognised that this beneficial use of large quantities is not possible in

practical terms. The extensive efforts made by Hamburg have in the end had little success. Either legal

requirements prevent this (for instance, not only contaminants are a limiting factor, but also organic materials

or salt content), or the costs are too high, e.g. for brick fabrication.

As long as the owners of the dredged material have to pay the costs of treatment themselves, this is not a

realistic option for disposing of large quantities. Only if a shortage in demand for raw materials occurs, or canbe created by fiscal measures, will thermal treatment become a viable option. Pre-treatment (which is alsoexpensive) is still necessary.

There remains confined disposal, for which ever higher requirements are formulated which ultimately further

increase costs. Although treated dredged material has a low water permeability because of the fine grain

content and would therefore be suitable as sealing material for disposal sites or e.g. dikes, the relevant

regulations tend to prevent this.

Sediments are an elemental element of aquatic systems and should remain there. For contaminated sediments,

the possibility of sub-aquatic disposal, of which there is experience in particular in the Netherlands and the

USA, and is also being looked at for the Hamburg dredged material, is a sensible option. The large quantities

produced in maintenance of waterways can only be relocated. On the long run this requires clean sediments.

The European Water Framework Directive may offer a chance of attaining this goal; however, so far

sediments have not appeared in the directive. It is a task for the near future to ensure that handling dredgedmaterial in waterways is put on a secure basis, and the plan of action to be drawn up in accordance with the

Water Framework Directive must contain measures to clean up the sources of the contamination.

9. CONCLUSION

Over the past 25 years, management of dredged material has changed significantly, not only in Hamburg.Although initially public protest was high, and little experience was available, in future the legal boundary

conditions for proper handling must be put on a secure basis.

For ports, the handling of dredged material is of great importance. This has not so far been reflected in

regulations. Dredged material with its particular characteristics has not been included in European or nationalregulations or is been covered with unreasonable requirements. The increasing density of regulation therefore

demands an agreed and active policy initiative by owners of sediment. In Europe these questions are being

discussed in SedNet, the network on this subject promoted by the European Commission. The Water

Framework Directive may offer an opportunity here by requiring the considerations of the whole river basin

to be taken into account with the aim of tackling properly understood sediment management.

As Hamburgs experiences show, to do this it is of great importance that open communication with all those

who are interested and with the public is of great importance.

REFERENCES

Detzner, H.-D. and R. Knies (2004). Treatment and beneficial use of dredged sediments from the Port ofHamburg. World Dredging Congress XVII


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Frstner, U. and G. Mller (1974). Schwermetalle in Flssen und Seen als Ausdruck der Umweltverschmut-

zung. Springer-Verlag, Berlin.

Lichtfuss, R. (1977). Schwermetalle in den Sedimenten schleswig-holsteinischer Fliegewsser - Untersu-

chungen zu den Gesamtgehalten und Bindungsformen. Dissertation Universitt Kiel.

Netzband, A. Reincke, H. and M. Bergemann (2002). The River Elbe - A case study for the ecological and

economical chain of sediments. Journal of Soil and Sediments, No. 3, pp. 112-116.

Netzband, A., Christiansen, H., Maa, B. and G. Werner (1998). Relocation of dredged material from

Hamburg harbour in the river Elbe. Water Science and Technology. Vol. 73/3, pp. 241-248.

Prange, A; et al. (1997). Geogene Hintergrundbelastung und zeitliche Belastungsentwicklung. GKSS For-

schungszentrum, Geesthacht.

Links

www.htg-baggergut.de

www.SedNet.org
http://www.htg-baggergut.de/http://www.sednet.org/http://www.sednet.org/http://www.htg-baggergut.de/

25 Years Dredged Material Policy in Hamburg

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