1 Introduction

Assessment of the Impact of an EC Directive on Priority Substances under the WFD on the Current Regulation of Contaminated Sites

1.1 Background
1.2 Objectives
1.3 Project scope and delimitation
- 1.3.1 Point sources
- 1.3.2 Diffuse contamination
1.4 Project Organisation

1.1 Background

The Water Framework Directive (2000/60/EC) was established to provide a new, comprehensive regime for the protection of inland surface waters, transitional waters, coastal waters and groundwater inter alia through measures towards chemical pollution from priority (hazardous) substances (Article 1, c). The WFD Article 16 requires the Commission to bring forward specific proposals on priority substances in surface waters.

The list of priority substances (including proposals for priority hazardous substances) was established already in 2001 by Decision no. 2455/2001/EC of the European Parliament and of the Council. Since then, work has been ongoing in the Commission to prepare the scientific basis for a Daughter Directive of the WFD intended to establish, among others, environmental quality standards (EQS) for the priority substances (PS) identify the substances to be regarded as priority hazardous substances (PHS), and defining the regulatory requirements applying to these substances.

The Daughter Directive proposal (COM(2006) 397 final) by the EC Commission was officially released in July 2006 and the consequences to Denmark of implementing the directive has been assessed in a separate report prepared for the Danish EPA by COWI A/S.

However, the possible importance of losses of PS/PHS from contaminated sites was only briefly touched upon in the report and therefore the Danish EPA decided to initiate a screening exercise regarding significance of soil and groundwater contamination in relation to the requirements of the Daughter Directive and clarifying to what extent achieving compliance with the directive would require further action to be taken by Denmark.

1.2 Objectives

The objective of this study is to make an initial technical assessment of the consequences for Denmark of implementing the Priority Substances Daughter Directive with emphasis on transport ("losses") of the priority substances from soil and groundwater pollution to surface waters. That is:

Assessing which of the priority substances that are expected to constitute a risk of exceeding the EQSs in the aquatic environment due to losses originating from soil and groundwater pollution
In continuation of that, give a conservative estimate on the number of sites polluted with the relevant priority substances and constituting a risk of exceeding the EQSs in surface waters.

Assessing which of the priority hazardous substances can be expected to constitute a risk of leaching into surface waters due to losses originating from soil and groundwater pollution

In continuation of that, give a conservative estimate on the number of sites polluted with the relevant priority hazardous substances and constituting a risk of surface water contamination.

1.3 Project scope and delimitation

The study was initiated in September 2006. The study includes soil and groundwater pollution due to contamination from point sources as well as diffuse sources, and includes both known sites and sites that has not yet come to the authorities' knowledge.

1.3.1 Point sources

All point sources will, as a starting point, be part of the project.

Major contaminations such as Høfde 42, Kærgård Plantage, Proms Kemiske Fabrikker and the like, will be handled separately on the basis of the recommendations Danish EPA received from the counties and an assessment of their relevance carried out by Ole Kiilerich, Danish EPA in consultation with COWI.

Regarding discharges from remediation facilities, this can be simplified to the following types:

Short-term discharges, e.g. in connection with dewatering of excavations or the like.
Long-term discharges, e.g. volume pumpings, demarcation of the contamination flare etc.

Relating to 1

The characteristic of these short-term discharges is that usually the water is so contaminated that it has to be treated before being disposed of to the surface waters. Generally, it needs to be treated before discharge to the sewage treatment plant. Treatment usually comprises active carbon treatment, treatment in an oil separator, if necessary supplemented with natural purification in a treatment plant. The purification is thus based on methods which usually purifies to a higher level than in the discharge demands e.g. Statutory Order 921 (1996). An increase of the discharge demands as a result of the Daughter Directive is not assessed to increase the cost of short-term discharges from contaminated sites substantially.

Relating to 2

The major part of the discharges from remediation facilities are led to sewage treatment plants. Discharges through the sewage system are included in the main report and are therefore not part of this study. Discharges which are led to surface waters are usually treated using methods with a high degree of purifying, and possible extra costs as a result of the implementation of the Daughter Directive are assessed to be negligible.

It is assessed that diffuse percolation from ongoing refuse dumps to surface waters, as a rule, is limited through the refuse dump authorisation and handling of percolate, and thus can be marginalised in the present investigation. Discharges from ongoing refuse dumps are included in the main screening project as they require actual discharge permissions.

With regard to disused refuse dumps, it cannot be ruled out that uncontrolled percolation/seepage of percolate to the groundwater or surface waters takes place. An estimate of disused refuse dumps where substances of relevance have been deposited and the distance to the surface waters thus implies a risk will be carried out.

1.3.2 Diffuse contamination

As a starting point, diffuse contamination is marginalised in the present investigation. This owing to the assessment that the major part of a possible percolation/seepage from diffuse contamination from e.g. roads is collected in drains and thus is part of the rainwater discharge dealt with in the main report. Pesticide residues in e.g. fields and on railway embankments are also covered in the main screening. In addition, it is assessed that spreading of diffuse contamination around source contaminations e.g. neighbouring contamination from major industries or the like to the surface waters will be marginal compared to the percolation/seepage of the source contamination.

The following areas are omitted in consideration of their essentiality:

Run-off of contaminated material from unpaved areas close to the point source straight to surface waters is marginalised, as it is assessed that this mass flow of contamination is very limited compared to e.g. run-off through the sewage system. Run-off through the sewage system is included in the main report.
Run-off of contaminated groundwater straight to surface waters through drain systems such as perimeter drain or field drain can locally constitute a potential route of spreading. Though the accumulated run-off of contamination through drains is assessed limited compared to other routes of spreading, the issue will be addressed briefly in section 3.4.
Particular transport (e.g. colloid transport) of contamination in the groundwater aquifer is left out, as it is assessed limited compared to all other transport of contamination in the groundwater zone.
Free phase contamination is not explicitly part of the assessment as it is assessed that free phase contamination in relation to surface waters is generally visible and included in the current legislation and practise. It is thus not expected to constitute additional costs in relation to Danish environmental management.

As initial dilutions for e.g. streams, lakes and the like, which are affected by percolation/seepage from soil contamination, are not yet defined, the necessary initial dilution in the surface waters will be estimated.

The geological model comprises two main geological types - a sandy and a clay soil type.

1.4 Project Organisation

The work was carried out by a team of consultants at COWI A/S consisting of Jesper Kjølholt (project manager), Tage Vikjær Bote, Dorte Glensvig and Marlene Ullum.

Ole Kiilerich, project responsible in the Danish EPA, has participated actively during the implementation of the project, in particular in the process of clarifying methodological issues.