Lessons learned in managing

contaminated sediments in the NL

Pol Hakstege

Independent consultant formerly with the Ministry of Infrastructure and the

Environment, the NL

company logo comes here

Contents

• Introduction

• Strategies on contaminated sediments

• Lessons learned from remediation, confined disposal, treatment and use

• Stakeholder management

• Port of Rotterdam

• Developments in legislation

• Outlook

The Netherlands – delta of 4 rivers

Scheldt Meuse

Rhine

Ems

4 WODCON 2010

Dredging in the NL

Dredging necessary for navigation, drainage, flood management, environment and ecology

Volumes about 25 - 30 Mm3/yr Excluding dredging

for coastal protection

12 Mm3/yr

Contamination peak 1970-1980

6

Strategies on contaminated water systems

Since about 1975 :

Source control to reduce emissions of contaminants

• On local and river basin scale • Cooperation with the industry • Enforcement of environmental legislation

Remediation of hot spots of contaminated sediments

Investments in source control upstream are more efficient than remediation downstream

7

Measures by Rijkswaterstaat (Ministry I&E)

• Construction of large sub-aquatic confined disposal facilities for heavily contaminated dredged material from maintenance and remediation (1988-2007)

• Remediation programme for clean-up of hot spots (1988-2015)

• Research programme for dredging, treatment and use of contaminated dredged material (1988-2009)

8

Confined Disposal Facilities RWS (1987-

2008)

Confined disposal facility Slufter (1987, 90 Mm3) RWS with Port Authority of Rotterdam

CDF IJsseloog

(2002, 23 Mm3) CDF Hollandsch Diep

(2008, 10 Mm3)

EIA first rejected NIMBY was overcome by public involvement

28

24

Dutch guidelines on CDFs

• Minimize fluxes to surface water: ring dike and cleaning effluent water (using a filter) before discharge

• Minimize fluxes to groundwater: anoxic conditions, impermeable layers underneath, if needed hydraulic head to create upward flow

• Monitoring results of groundwater show that emission is negligible even less than expected

• Design provides inherent environmental safety

10 10

Remediation programme 1988-2013 Clean-up of rivers, lakes, harbours, seaports

Tens of Mm3 by removal and/or capping

Example Petroleum harbour Amsterdam

11

Remediation options

Removal of contaminated sediments Partial removal

Active capping with clean dredged material Capping by natural sedimentation

Lessons learned from remediation

• Only effective after control of the sources of emissions

• Remediation option: reduction environmental risks vs. costs

• Site-specific risk assessment • Cost factors: dredging method, production rate,

removal %, logistics, most of all selected destination • Sub-aquatic deposition in CDFs has proven to be an

environmentally sound and cost-effective solution • Consultation of stakeholders and public is crucial

(NIMBY)

National approach 2000-2001

10 yr scenario

• Problems

– Lack of destinations for contaminated dredged material

– Low priority on political level

– Lack of finances

– Backlog in dredging

Participatory approach

Involvement of • Ministries • National water authorities (RWS) • Regional water authorities (water

boards) • Municipalities/Port Authorities • Provinces (coordination) • Private sector • General public Communication • Meetings, workshops • Articles, newsletters • Reports

Results 10 yr scenario

• Issue of contaminated sediments on political agenda

• Common understanding of costs and benefits of dredging for society

• Financial arrangements to increase dredging

• Encouragement of treatment and use

• Changes in regulations

• Realisation of more disposal capacity in CDFs and pits

16

Borrow pits

• Many deep borrow pits (sand and gravel), both inland and near-shore present opportunities for storage of DM

• Poor conditions for ecological development (anoxic zone, steep sides)

• Morphological or ecological improvement or just disposal

• Compliance with legislation Soil Quality Act, WFD, Bird and Habitat Directives

• Practical and cost-effective solution

• Public concern on contamination was overcome by adjustment of regulations and good communication

Treatment and use

• During 20 years R&D and pilots on treatment and use of dredged material

• Techniques (biological, chemical, thermal) to produce building materials

• Market potential of products

• Logistics and costs

• Large-scale pilot 500.000 m3

18

Simple treatment techniques

• Treatment with simple techniques to reduce the volume for disposal at CDFs can be effective

• Sand separation in sedimentation basins (common practice) • Natural dewatering in lagoons (pilots)

Indication of treatment and disposal costs

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60

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• Excluding transport, handling, buffering • Price level 2006, in Europe

Lessons learned from treatment & use

• Treatment of contaminated dredged material into building materials is technically feasible

• In general high costs of treatment for complex techniques (no economic feasibility)

• Much more costly than disposal in CDF

• Difficult to compete with primary raw materials (price, quality and acceptance)

• Negative public perception due to stigma of waste

Soil Quality Decree (Water Act) Chemical Standards for use dredged material inland/at sea

Background

Intervention-level

In general no use

but CDF

No restrictions for use

Actual level Use/Resource

No use

Class A

Class B

Disposal/Waste

Distinction hotspots and

diffuse contamination of sediments

Background quality of

sediments in River Rhine

Site-specific risk assessment of

contaminated sediments

Relocation at the North Sea

• Compliance with action levels from Soil Quality Decree

• No obligation to use bio-assays (doubts on reliability)

• Beneficial use if relocation supports morphology and/or ecology (sustainable relocation)

• Sandy dredged material used for beach nourishment (background quality) and coastal foundation

23 23 23

Sustainable relocation

Relocation of dredged material into

surface water to maintain sediment

balance for coastal defence/against

soil erosion/ecosystems

North Sea River Waal

Engineering and environmental uses

25

Port of Rotterdam

25

• Maintenance dredging for Port of Rotterdam: 5-7 million m3/year

• Channels maintained by RWS • Docks maintained by Port of Rotterdam

25

CDF Slufter

Relocation areas

26

Decrease in disposal volumes in CDF Slufter

Rotterdam

Gebaggerde m3

0

1.000.000

2.000.000

3.000.000

4.000.000

5.000.000

6.000.000

7.000.000

8.000.000

1988

1990

1992

1994

1996

1998

2000

2002

2004

2006

2008

2010

Jaar

ho

eveelh

eid

in

mio

m3

m3 zee

m3 Slufter

27

Reasons for less disposal in CDFs

• Successful emission policy which led to a significant improvement of sediment quality

• Increase in possibilities for use of (contaminated) dredged material due to new legislation Soil Quality Decree (2008)

• Change of remediation criteria, leading to less need for remediation

Remediation criteria

Risk assessment based on bio-

availability of contaminants

Sediment Discharge Test

A tool for assessing the effect of a physical intervention in sediments on the chemical water quality objectives of the Water Framework Directive Determines both for the existing riverbed and for the new river bed: • discharge of substances from the sediment • effect of discharge from the sediment on water quality • allowed emission in the water phase based on the difference between

existing water quality and water quality objective

Determines whether this increase in discharge due to physical intervention exceeds allowed emission in the water phase = testing “no deterioration” principle www.helpdeskwater.nl/sdt www.helpdeskwater.nl/sedimentdischargetest

Outlook

• The quality of sediments has tremendously improved which enables direct use of the vast majority of dredged material

• Less capacity needed in CDFs, some will be closed in the near future with opportunities for other uses

• Remaining challenge is increase in complexity of legislation

Thank you for your attention