2 Methodology

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

2.1 Step 1
2.2 Step 2
2.3 Need for further action

The main objective of the current Danish legislation on contaminated soil and groundwater is to protect human health and groundwater resources. Therefore, measures to protect contamination of surface waters from soil and groundwater pollution are rare. However, protection of surface waters often occurs as a side-effect when measures to protect groundwater resources are implemented.

The objective of this project is to identify substances and types of soil and ground water contamination that can cause pollution of surface waters, without being discovered by the present legislation and administration. At these sites further action can be relevant to ensure that the proposed EQSs for priority substances in surface water are not exceeded. Further action can also be relevant to cease the leaching of priority hazardous substances (PHS).

It is noted that the framework of the project does not permit a detailed assessment, but only an introductory screening of the consequences of implementation of the Directive on 33 priority substances under the Water Framework Directive.

The Daughter Directive proposal also establishes EQSs for a number of "other pollutants" (OP) (Annex I, Part B), i.e. some chemicals that are not priority substances but substances which were previously included in a number of directives that will be repealed by 2013 (Directives 82/176/EEC, 83/513/EEC, 84/456/EEC, 84/491/EEC and 86/280/EEC). These eight substances have been included in this project equally to the priority substances.

The screening of the priority substances and contamination situations is divided into two steps:

Step 1: Identification of substances (PS, PHS and OP) used in Denmark and types of contaminated sites where these substances are/were handled (Chapter 3).
Step 2: An assessment of the number of sites in Denmark contaminated with the identified substances of relevance and constituting a risk of exceeding the EQSs in surface waters or risk of priority hazardous substances (PHS) leaching into surface waters (Chapter 4)

Based on step 1 and 2, an assessment of the need for further action to be taken by Denmark to ensure that the EQSs are not exceeded due to soil and groundwater contamination will be carried out (Chapter 5). The assessment also includes the need for action if Denmark decides completely to cease the leaching of hazardous substances (PHS) from polluted sites to surface waters.

2.1 Step 1

Step 1 is based on five elements:

Use and production in Denmark
Substance characteristics
Will the contamination be detected in the framework of common administration of soil and groundwater pollution?
Types of contamination situations of concern
An overall assessment of substances and types of contaminated sites of relevance based on the previous four elements

For every element in the screening, the substances are divided into two to five groups, depending on whether or not we assess the substances to be of interest in relation to the objective. At the final assessment, the result of each element is used in an overall assessment of substances of concern. In the following, the five elements are briefly described.

2.1.1 Use and production in Denmark

The basis for the data is the PS screening project (2005), expert knowledge contributed by Jesper Kjølholt, Tage Bote and Dorte Glensvig and general knowledge available in COWI. This means that further collection of use and production data has not taken place.

Substances which have not been used or produced in Denmark were screened out. Furthermore, only limited focus has been given to substances which have only been used or produced on a small scale in Denmark.

2.1.2 Substance characteristics

The county of Copenhagen was contacted for information on the prioritization system GISP with the purpose of assessing the hazardousness of the individual substances towards the groundwater resource, as an indicator of how easily they spread in the water environment.

Substances which are rather or relatively immobile in the groundwater environment were screened out and the substances which are moderately or highly mobile were singled out.

2.1.3 Will the contamination be detected in the framework of normal practice/legislation?

Legislation and practice have been described as a starting point for assessing which contamination situations are expected to be managed in the framework of environmental legislation.

Basically, it has assumed that as long as the substances are covered by common practice and legislation, they do not pose a risk or need for further actions or increased environmental costs. In other words, if investigations of the substances in relation to soil and groundwater are generally carried out, additional actions for implementing the Daughter Directive are not expected, and the combination of location and substance are screened out. An exception is the situation where the limit values in the Daughter Directive (EQS) are lower than the limit values normally used (groundwater quality criteria (GQC)). In these situations the combination of location and substance were singled out.

A comparison of the groundwater quality criteria (GQC) and the proposed EQS values have therefore been carried out. Depending on the difference between GQC and EQS a prioritizing of the substances were carried out.

Only a limited number of substances will be detected during normal groundwater monitoring and investigations of contaminated sites, causing a risk that some prioritized substance will not be detected or remediated.

The laboratory Eurofins Danmark A/S was contacted regarding how frequently ground water analysis includes the priority substances. This has been used as an indication of how often common practice includes the priority substances in investigations of soil and groundwater contamination.

2.1.4 Types of contaminated sites and spreading of contamination

A number of conceptual models for contamination of soil and groundwater and run-off to surface waters have been established. Estimates on natural dilution in both the groundwater zone and when the groundwater contamination reaches the surface waters were carried out. As initial dilution factors for non point releases to the surface waters were not available, the need for natural dilution to reach the EQSs in the surface waters have been estimated and evaluated based on expert knowledge.

2.1.5 An overall assessment of substances and contaminated sites of relevance

Based on the results of the previous four elements an overall assessment of substances and types of contaminated sites of relevance is carried out: which of the 41 substances and which types of contaminated sites are expected to constitute a risk of exceeding the EQSs in surface waters.

Priority hazardous substances are specifically included in the assessments.

2.2 Step 2

In step 2, results from step 1, especially the fifth element regarding substances and types of contaminated sites of relevance, is used as the starting point of identifying a realistic number of sites constituting a risk of exceeding the EQSs in surface waters and thus requires further action to be taken by Denmark to ensure that the EQSs are not exceeded.

Furthermore an assessment of the number of sites contaminated with the priority hazardous substances is given.

2.3 Need for further action

Based on step 1 and 2 an overall assessment is carried out. The assessment is based on the need for further action to ensure that none of the priority substances (PS) and other pollutants (OP) exceed the proposed EQSs, and to meet the aim of ceasing the leaching of priority hazardous substances (PHS) into surface waters.