SedNet Conference 2008
5th
International SedNet conference 27th-29th May 2008,
hosted and co-organised by NGI, Oslo, Norway
Urban Sediment Management and Port
Redevelopment & Sediment in River Basin Management Plans
 The
5th International SedNet Conference was hosted and
co-organised by the Norwegian Geotechnical Institute. It
took place in Oslo, Norway. More than 50 presentations
were given and about 40 posters were shown. The
conference was attended by 180 sediment experts from 19
countries.
The first part of the
conference was dedicated to the main title. Sediment in
rivers, harbours and marine coastal zones in urban areas
is often historically contaminated. Contamination
originates from industrial activities, dockyard and
harbour operations as well as discharges of municipal
wastewater and urban surface water run-off. This ‘legacy
of the past’ complicates the redevelopment of harbour
areas and the waterfront of cities for housing or
commercial purposes. A proper sediment management
strategy is required that takes into account
environmental risks associated with contaminated
sediment as well as the identification of appropriate
remediation options for use in the urban environment.
Furthermore, European legislation increasingly requires
the involvement of stakeholders, who may have
conflicting viewpoints and concerns. How to manage such
complexity? What challenges with regard to the
management of contaminated sediments have been met and
what experiences gained in port redevelopment cases in
urban areas?
The second part of the conference was dedicated to the
state-of-the-art on sediment management in river basin
management planning. By this conference part a European
discussion was continued which was started in 2006 in
Venice with the SedNet Round Table Discussion "Sediment
Management – an essential element of River Basin
Management Plans".
At the end of each
session, the session chairman summarized the highlights
or conclusions. It is foreseen to give a more in-depth
summary in the Journal of Soils and Sediments in 2009.
|
Surveys (chairman Aivo
Lepland, Geological Survey of Norway) |
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• |
The importance of fine,
clayey fractions became clear. |
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• |
Combination of
high-resolution acoustic techniques with
sediment core data provides insights for
reliable assessment of thickness and volume of
sediments. |
|
• |
Sediment Profile Imaging (SPI)
is a promising and quick tool for environmental
monitoring of the seabed and capping. |
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• |
Modelling of sediment
spreading during dredging and deposition of
dredged materials using hydrodynamics and
sediment properties; verifications from the
field are still required. |
Solutions (chairman Audun Hauge, Norwegian
Geotechnical Institute) |
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• |
Capping is becoming a widely
used remediation technique. |
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• |
Focus on developing active
caps. |
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• |
Stabilization and
solidification of dredged material in land
reclamation gives good results. |
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• |
Special recipies must be
found for each situation. |
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• |
For management of
contaminated sediments in fjords with ongoing
contaminant sources dredging is not the
solution. Thin layer capping with sandy material
is a better option. |
|
• |
“Remediation efficiency”
tools can be useful for both pre-design
assessment and post-construction monitoring of
engineered caps. |
|
• |
Capping of contaminated
sediments has the potential to severely alter
the soft bottom fauna community structure. |
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• |
Incorporating contaminant
budget principles has been a good tool for
communicating the progress and status of
remediating activities for environmental
authorities and stakeholders. |
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• |
Design and construction
aspects of remediation projects offer numerous
insights and lessons for other projects of any
scale. |
Sediment Quality Standards (chairman Piet den
Besten, Centre for Water Management, NL) |
|
• |
SQS require the incorporation
of a huge number of scientific considerations
(most of them valid, but making the work very
complex). |
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• |
As a consequence, use of SQS
in the near future will still leave a lot of
uncertainties. |
|
• |
Earlier evaluations of strong
and weak points of the application of SQSs (e.g.
Pellston workshop : Use of Sediment Quality
Guidelines and Related Tools for the Assessment
of Contaminated Sediments: Proceedings from the
Pellston Workshop on Use of Sediment Quality
Guidelines and Related Tools for the Assessment
of Contaminated Sediments, 18-22 August 2002,
Fairmont, Montana, USA. Editor Richard J.
Wenning, SETAC 2005 (ISBN 1880611716,
9781880611715) seem to have been ignored.
Concerns about the use of SQSs reported earlier
are: |
| |
– |
The
ability to adequately predict the presence or
absence of chronic toxicity to sediment-dwelling
organisms under field conditions; |
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– |
The
ability of SQSs to predict effects caused by
accumulation in foodchains; |
|
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– |
Doubts
whether SQSs can be used to demonstrate
cause-effect relationships; |
|
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– |
Concern
whether SQSs based on particular endpoints can
be used to predict other toxicity endpoints and
mechanisms. |
|
• |
The linkage between SQSs and
management objectives (WFD!) should be made
clear (and be the joint product of
stakeholders). |
|
• |
Application of SQSs as
trigger values (in tiered approaches) is a way
of getting around scientific discussion on the
uncertainties of those SQS values. |
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• |
A risk assessment framework
based on the use of SQSs could also consist of
two sets of SQS values: a high value, above
which there will be no discussion about
necessity of measures, and a lower value
triggering further research. |
|
• |
The scientific community has
shown many times the advantages of tiered
approaches (with also the use of biological and
ecotoxicological parameters). |
|
• |
Communication is needed about
existing experience in EU countries with
specific methods how to derive SQSs and the way
these are used in risk assessment or in
pass/fail quality assessment steps. More insight
is needed in the benefits and in the
disadvantages of these frameworks, thus enabling
a better EU-wide discussion on the perspectives
of a (rigid) sediment management system based on
SQSs. |
Emerging Issues (chairman Jos Brils, Deltares,
NL) |
|
• |
Effective management not only
requires a good understanding of the biophysical
system, but also of the social system, and
specifically of the dynamic and complex
interaction between both systems. Hence, all
stakeholders should be involved. |
|
• |
Spatial planning, such as
port revitalisation, is a good opportunity to
also address (contaminated) sediment issues.
Hence, a ‘sediment check’ – like the water check
(‘Watertoets’) in the Netherlands – should
become obligatory in spatial planning. |
Science for River Basin Management
(chairperson Susanne Heise, BIS TU Hamburg-Harburg)
|
|
• |
Sediment management
objectives need to be driven by regional risk
reduction aiming at improvement on river basin
scale. |
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• |
For regional risk reduction,
research gaps need to be reduced and they
comprise quality as well as quantity issues, as
well as linking scientific assessment to
decision support systems for stakeholders. |
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• |
Important quality issues:
–
remobilization of contaminants from sediments
–
biological activity may have secondary effects
by gas-production |
|
• |
Important quantity issues:
–
what
happens during flood events e.g. with retention
areas in terms of resuspension and setting of
material (models may help us understand and
generalize) |
|
• |
Decision support systems
comprising tiered approaches, developed by
scientists in cooperation with stakeholders are
useful tools which are both economic and support
sound science. |
|
• |
Extensive projects like
Risk-Base and others stress the importance of
RBM but integration of field-specific expertise
and regional oriented perception still remains a
challenge. |
River Basin Management – Fundamentals
(chairman Peter Heininger, Federal Insitute of
Hydrology, Germany) |
|
• |
River basin in many respects
represents the most appropriate unit for
sediment management decision making. |
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• |
Sediment management in terms
of quality and quantity should receive due
attention in River Basin Management Plans
including programmes of measures. Exceptions
from including sediment management into the
plans should be justified. |
|
• |
As the plans of the 1st
management cycle are now well developed it is
time to analyse critically whether sediment
management has been accounted for to the
necessary extent. Conclusions for the 2nd and
3rd cycles have to be drawn. |
|
• |
There is a strong need for
developing decision support tools for sediment
management, e.g. to assist in balancing the
costs and benefits of management options. |
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Efforts towards a better
linking of river and coastal/marine management
should be further intensified. The marine
strategy aims at a “good environmental status”
whereas the WFD aims at a “good ecological
status”. This seems to be a progress in
thinking. |
|
• |
A general knowledge base on
risk assessment approaches and merging the
concepts, approaches and models for specific
risks (e.g. contamination, erosion) into a
common scheme of integrated risk assessment at a
river basin scale is required. |
|
• |
Geochemical mapping
(monitoring), particularly of overbank
sediments, may be a powerful tool to better
understand particle bound fluxes and thus to
develop management plans. |
River Basin Management - Aspects of sediment
quality (chairman Igor Liska, ICPDR, Austria) |
|
• |
Sediments play an essential
role in urban river basins, however this is
often neglected in the management policies.
Water quality in municipalities is influenced by
the presence of sediments and this has to be
taken into consideration in preparation of river
basin management plans. |
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Contaminated sediment
remediation must be supported by an effective
system of assessing the risks related to the
manipulation with a dredged material to avoid
any adverse impacts on the status of the water
bodies. |
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High annual throughput of
sediment remediation projects necessitates
availability of appropriate expert and
management systems for risk assessment of
dredged material; these expert systems should
include quality assurance aspects to guarantee
compliance with the standards. |
In his concluding
speech, Axel Netzband, chairman of SedNet, remarked that
SedNet has the aim to give attention to the issues that
have come forward at the Oslo conference. The conference
clearly showed that SedNet’s scope now is much broader
than the original one. Not only are contaminated
sediments in inland waters the main topic, but also
sediment quantity management, and the scope reaches from
the source of a river to the marine environment. SedNet
is open for a very broad discussion and therefore would
appreciate more active members. Anyone who is interested
in playing an active role in SedNet is requested to
contact the SedNet secretariat
(marjan.euser@tno.nl).
EC Best Paper 2008
Award
At the end of the conference, the Environment Commission
(EC) of the Central Dredging Association, CEDA,
presented its 2008 Award for a contribution to the
literature on dredging and environment at the SedNet
conference. CEDA EC has established this award to
stimulate the dissemination of good quality information
related to dredging and the environment, including
technical, regulatory and managerial aspects of dredging
operations and dredged material management. The Prize is
€ 1000 in cash and the publication of the full paper in
Dredging and Port Construction Magazine. The winning
abstract was 'The Oslo Remediation Project' by Torild
Jørgensen of the Oslo Port Authorty. The price was
handed over by Anders Jensen, vice-chairman of the CEDA
EC.
Abstracts and slides of the oral and
poster presentations can be found on in the
library.
Organising
Committee
Piet den Besten, Centre for Water Management, The
Netherlands
Gijs Breedveld, Norwegian Geotechnical Institute, Norway
Jos Brils, Deltares, The Netherlands
Marc Eisma, Port of Rotterdam Authority, The Netherlands
Audun Hauge, Norwegian Geotechnical Institute, Norway
Susanne Heise, TU Hamburg-Harburg, Germany
Peter Heininger, Federal Institute of Hydrology, Germany
Igor Liska, ICPDR, Austria
Hans-Peter Nachtnebel, University of Vienna, Austria
Axel Netzband, Hamburg Port Authority, Germany
Sue White, Cranfield University, UK
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