ELECTRONIC SUPPLEMENTAL MATERIALESMPERTAINING TO SECTION 7

A decision framework for possible remediation of contaminated sediments in the River Kymijoki, Finland

General remediation plan (

Contents

1.Summary

2.Introduction

3.Scope and methods

4.Overview of River Kymijoki pollution

5.Overview of sediment remediation methods

Dredging methods

Stabilization methods

Capping

6.Preliminary cost-benefit analysis

Technical feasibility and cost-efficiency

Future trends in contaminant concentrations

Contaminant transport without remediation (null hypothesis)

Contaminant transport after remediation

Resuspension during remediation

Remediation risks and benefits

Remediation risks by sub regions

Summary of remediation risks by methods

Priority of remediation by sub region

7.General remediation plan

Sub region 1 (Kuusankoski-Keltti)

Preconditions for remediation

Dredging

Sludge treatment and end location

Sediment end location

Capping

Recommendation for remediation method

Sub region 2 (Keltti-Myllykoski)

Sub region 2.1

Sub region 2.2

Sub region 2.3

Sub region 2.4

Recommendation for remediation method

Sub region 3 (Myllykoski-Gulf of Finland)

Sub region 3.1

Sub region 3.2

Sub region 3.3

Recommendation for remediation method

Sub region 3.4 (Tammijärvi)

Recommendation for remediation method

Monitoring

Timing of remediation

8.Recommendations for future measures

Bibliography

Appendixes

Matrix of the combined effect of seriousness and probability for risk used in the ranking of different risks between remediation methods. For example, the deficiency of information regarding geotechnical characteristics (affecting the success of the work) was regarded as very serious with a strong possibility of risks when using the capping method within a fast flowing river and thus having ranking points of 16. This procedure was performed for each identified risk and remediation method (see the list of risks in chapter 6).

Seriousness/probability / Low
1 / Harmful
2 / Serious
3 / Very serious
4
Low probability
1 / Insignificant risk
1 / Low risk
2 / Acceptable risk
3 / Moderatee risk
4
Occasional
2 / Low risk
2 / Acceptable risk
4 / Moderate risk
6 / Significant risk
8
Probable
3 / Acceptable risk
3 / Moderate risk
6 / Significant risk
8 / Severe risk
12
Strong possibility
4 / Moderate risk
4 / Significant risk
8 / Severe risk
12 / unbearable risk
16

An example of the comparison of cost efficiency between different sub regions for the dredging option including sludge treatment and sludge and sediment end location at site. A similar procedure was performed for PCDD/Fs and mercury and for dredging and capping options.

Sub region / Burden of contaminated sediments
m3 / Costs/m3
€/m3 / Total costs
€ / Amount of PCDDF/s
kg / Cost efficiency
€/kg
Sr1 / 90,000 / 100 / 9,000,000 / 1,400 / 6,500
Sr2 / 350,000 / 100 / 35,000,000 / 1,450 / 24,200
Sr3.1 / 430,000 / 100 / 43,000,000 / 900 / 47,800
Sr3.2 / 330,000 / 100 / 33,000,000 / 370 / 89,200
Sr3.3 / 720,000 / 100 / 72,000,000 / not known / –
Sr3.4 / 2,900,000 / 100 / 290,000,000 / 1,820 / 159,400