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

3 Step 1 - Substances and types of contaminated sites of relevance

• 3.1 Present and historical uses of the 41 substances
• 3.2 Physical-chemical properties
• 3.3 Present administration and legislation
  • 3.3.1 Acts and orders
  • 3.3.2 Quality Guidelines
  • 3.3.3 Practice on environmental investigations and assessments
  • 3.3.4 Acts, orders and practice in relation to project objective
  • 3.3.5 Identification of substances of concern regarding quality standard scenarios
  • 3.3.6 Substances of concern regarding practice on analysis
• 3.4 Types of contaminated sites of concern
  • 3.4.1 Dilution of contaminated water leaching from point sources
  • 3.4.2 Dilution trough drainage systems
• 3.5 Substances constituting a risk of exceeding EQSs
  • 3.5.1 Relevant substances
  • 3.5.2 Need for dilution to comply with the EQS
• 3.6 Phase out of hazardous priority substances

3.1 Present and historical uses of the 41 substances

In the following chapter, an assessment of substances of relevance regarding use and production has been conducted. The assessment is based on the assumptions and delimitations mentioned in chapter 2.

Table 3.1 summarizes data from Kjølholt et al (2005) on present and historical production and uses of the 33 priority substances under the Water Framework Directive and the 8 other pollutants. The data in the table are based on the PS screening project regarding present use and on fingertip knowledge regarding historical use, as the framework of this project does not include further detailed investigation into e.g. production sites in Denmark, handling methods or investigation of contaminated sites.

Table 3.1
Present and historical uses of the 33 priority substances and 8 other pollutants under the Water Framework Directive. Priority Hazardous Substances (PHS) are marked in bold. Other pollutants (OP) are marked with a # .
Data source: PS Screening Project (Kjølholt et al., 2005) + DK Pesticide Statistics.

As it appears from table 3.1, it is assessed that some substances have not been used or produced in Denmark. These are:

• Hexachlorobenzene
• Hexachlorobutadiene
• Pentachlorobenzene
• Isodrin

Furthermore, certain substances are expected only to have been used in Denmark in limited quantities and are therefore not expected to be of relevance regarding the objective of the project. Using 1 tons/year as a limit, these are:

• Aldrin
• C10-13-chloroalkanes
• Chlorfenvinphos (as an average)
• Chlorpyrofos
• 1,2-dichloroethane
• Dieldrin
• Endrin

In table 3.2 below (only showing the pesticides among the 41 substances in table 3.1), an assessment of the risk of a point source of pesticide in soil and groundwater is given. Based on the delimitation in chapter 2, the assessment does not include diffuse contamination such as pesticide residues in e.g. fields and on railway embankments due to spreading of pesticides.

The assessment is based on the following principles:

• If the pesticide has only been used in a small amount, and have not been produced in Denmark, it has been screened out as not relevant regarding point sources
   
• If the pesticide has only been produced in Denmark, but has not been used, it has been assessed as relevant regarding point sources.

If the pesticide has been produced in Denmark, the production company is mentioned in brackets.

Table 3.2
An assessment of the risk of point source of pesticides based on data in table 3.1 and expert knowledge from Jesper Kjølholt. ^1: Amount used in agriculture and not including possible Danish production

It is seen from table 3.2, that 4 out of 12 pesticides have been assessed not relevant. An overall assessment is made in chapter 4.

3.2 Physical-chemical properties

In table 3.3, the physical and chemical properties of the 41 substances under the Water Framework Directive are summarized.

Table 3.3
Environmental characterization of the 41 priority substances and other pollutants under the Water Framework Directive based on their physical-chemical properties and degradability in soil. Priority Hazardous Substances (PHS) are marked in bold. Other pollutants are marked vith a #.
Data source: PS Screening Project (Kjølholt et al., 2005).

For each of the 41 substances, an assessment of the ability of the substance to spread from a soil or groundwater contamination to surface waters has been carried out. The assessment is based on the prioritizing system GISP (1996) and an assessment of the mobility and degradability of the substances.

The following principles are used in the screening of substances of relevance:

• The mobility of the substances is evaluated regarding solubility and affinity to particular matter (Log Kow). The evaluation of solubility and affinity is based on the principles in GISP.
  
  

  Solubility		Log Kow
  >1,000 mg/l	High	<3	High
  1 - 1,000 mg/l	Medium	3 - 4	Medium
  <1 mg/l	Low	>4	Low

  
   
• The assessment of degradability of the substances is based on the aerobic degradability of the substances in groundwater measured as the half time constant (T½). The degradability of the substances often changes with different redox-conditions. Aerobic degradability has been chosen for the assessment due to the fact that most shallow groundwaters are aerobic.
  
  

  Aerobic degradability T½
  >60 days	Slow
  15 - 60 days	Medium
  <15 days	Fast

  
   
• Substances will be screened out if they are relatively immobile in the groundwater environment or if the substances are moderately mobile and highly degradable.
   
• Substances will be singled out if they are highly mobile or if the substances are moderately mobile and slowly degradable.

The assessment is given in table 3.4.

Table 3.4
Assessment of the ability (risk) of substances to travel from a soil and groundwater contamination to surface waters of the 41 substances under the Water Framework Directive based on their physical-chemical properties and degradability in soil. The assessment is furthermore based on the principles in GISP and the data in table 3.3.

Substances are screened out if they are relatively immobile in the groundwater environment or if the substances are moderately mobile and highly degradable.

The following 16 substances have been screened out:

• Aldrin
• Anthracene
• Pentabromo diphenylether
• Cadmium + compounds
• C10-13-chloroalkanes
• Chlorpyrifos
• DDT
• Dieldrin
• Di(2-ethylhexyl) phthalate
• Endrin
• Fluoranthene
• Lead + compounds
• Mercury + compounds
• Nickel + compounds
• PAH
• Trifluralin

An assessment of the risk of the substance to spread from a soil or groundwater contamination to surface waters has been supplemented with an assessment of the toxicity of the substances stated as the Environmental Quality Standard (EQS) of the substances. In the assessment, the following principles have been used:

• The principles of graduating the Groundwater Quality Criteria (GQC) from GISP is used on the EQS:
  
  

  Toxicity
  EQS	Assessment
  <1 µg/l	High
  1 - 10 µg/l	Medium
  >10 µg/l	Low

  
   
• The daughter Directive on priority substances includes two types of Environmental Quality Standards (EQS); for "Inland surface waters" and for "Other surface waters". A few substances have the lowest EQS value for "Other surface waters", but for most of the substances the EQSs are identical. Whether EQS are used for "Inland surface waters" or for "Other surface waters", the score for toxicity in Table 3.5 are the same.

The assessment is given in table 3.5 and is combined with the results from table 3.4 using the following principles:

• If both risk of spreading of substance from soil and groundwater to surface waters and high score on toxicity, the overall assessment is high risk for surface waters.
• If low risk on spreading of substance from soil and groundwater to surface waters the overall assessment is low risk independent of the toxicity.

Table 3.5
Assessment of the toxicity of the 41 substances under the Water Framework Directive based on GISP and Environmental Quality Standards (EQS) for inland surface waters. The toxicity assessment is combined with the risk assessment from table 3.4 regarding risk of spreading from soil and groundwater contamination to surface waters.

Substances will be singled out if they are 1) highly mobile or if the substances are moderately mobile and slowly degradable and 2) considered highly toxic. The following four substances are singled out:

• Alachlor
• Atrazine
• Diuron
• Trichloroethylene
• Trichloromethane

Please see table 3.10 for an overall assessment on transport and toxicity of the substances in the soil and groundwater environment.

3.3 Present administration and legislation

This section presents an assessment of which priority substances there may be a need for further action by Denmark. The assessment is based on the assumptions and delimitations mentioned in chapter 2.1.3.

3.3.1 Acts and orders

Soil and groundwater contamination and subsurface run-off of pollutants such as the priority substances to surface waters are regulated by several acts and ministerial orders. Regarding the objective of the project, the most relevant ones are:

• ENVIRONMENTAL PROTECTION ACT, part 4 includes administration of pollution of surface waters, both subsurface run-offs from contaminated sites and sewage waters.
   
• CONTAMINATED SOIL ACT, Act no. 370 of 2 June 1999, which does not specifically address surface waters. It states in part 1 that the act shall apply to soil which due to human impact may detrimentally affect the groundwater, human health, and the environment. Furthermore it states, that this act shall not apply to soil affected by the spreading of sludges, fertiliser, and pesticides, etc. for agricultural purposes.

These acts and orders constitute the basis for all environmental investigations and assessments carried out in Denmark. From the list above, it should be expected that inland surface waters, transitional waters and coastal waters would be fully and comprehensively included in all investigations and assessments except for those few exceptions mentioned above, such as pollution on agricultural areas. In practice, however, risk assessment of inland surface waters, transitional waters and coastal waters due to contaminated sites is only carried out in a limited number and are generally superficial/introductional.

In the following chapter, a brief overview on quality standards used on surface waters as well as a summary on environmental practice in Denmark regarding contaminated sites and surface waters is given.

3.3.2 Quality Guidelines

As mentioned in the previous chapter, several types of quality standards are used in risk assessing the effect of subsurface run-off from contaminated sites to surface waters such as inland surface waters, transitional waters and coastal waters.

• Groundwater quality standard (GQS): Standards defined by the DANISH EPM and valid for the primary reservoir. Groundwater quality standards for the secondary water body above the primary reservoir are typically defined as 10 times GQS based on expert knowledge.
   
• Environmental quality standard (EQS) listed in the proposal for Daughter Directive to the Water Framework Directive (WFD) addressing priority substances in the aquatic environment.

3.3.3 Practice on environmental investigations and assessments

As the acts and orders mentioned above leaves room for the Ministry of Environment or the counties to prioritise the effort, the reality is that the environmental investigations and risk assessments are focused primarily on drinking water interest. This means that in case of a polluted site, investigations and risk assessments towards surface waters are either not relevant or only carried out as a superficial view.

Common practice on environmental investigations and assessments regarding contaminated sites and surface waters are described below.

• Since the ratification of the Contaminated Soil Act, investigations have primarily been focusing on "Particularly valuable water abstraction areas" large enough to ensure the future supply of pure drinking water. Presently, these cover 34 % of the area of Denmark (DANISH EPM 2006), see figure 3.1. As a consequence, most investigations have been carried out at a distance from transitional waters and costal waters. This means that the knowledge on number of sites close to coastal and transitional waters contaminated with e.g. priority substances, is limited.

Figure 3.1:
Water abstraction areas. From Danish EPM's homepage (Danish EPA 2006).
Particularly valuable waters cover app. 34% of the area of Denmark, valuable waters cover app. 53%, and less valuable waters cover app. 13%.

• When planning an investigation on a potentially contaminated site, practice is that if use of a certain substance on the site has been limited compared to other relevant substances which are known to pose a risk of groundwater contamination, the lesser used substance will not necessarily be included in the investigation.
   
• If a substance - such as a metal or a PAH - is not expected to travel easily in the groundwater aquifer it will not be included in groundwater investigations.
   
• Basically, surface waters are not investigated unless the surface water is located right next to the contaminated site or if there is visual evidence of contamination in the surface waters such as free phase contamination.
   
• National surface water quality standards (WQS) are generally not included in the investigation or the risk assessment unless the site is located right next to costal waters. Even in cases where sites are located right next to surface waters, WQS have seldom been used. Instead GQS have been used.
   
• If inland surface waters or transitional waters are located closer than approx. 100 m from a contaminated site, risk assessment regarding these waters generally use groundwater quality standards GQS as bench markers for the risk.
   
• If inland surface waters or transitional waters are located more than approx 100 m from a contaminated site, risk assessment regarding these waters is not carried out.

3.3.4 Acts, orders and practice in relation to project objective

It is expected that, in general, the present administration of groundwater and soil contamination will handle contamination with any of the 41 substances under the Water Framework Directive. This is owing to the administrative practice that all types of contaminants can be included both in investigations and in remediation. However, experience on general practice shows that including a substance in an investigation is on the condition that the substance has been used or produced in a significant quantity and that it is supposed to constitute a substantial part of the contamination. In general, this means that including a priority substance in an investigation on a site, presupposes that the amount of the priority substance is several per cent of the total use of chemicals per year. As an example - atrazine will not automatically be included in the investigations if the yearly use is up to 100 kg atrazine compared to 10 tons of chlorinated solvents such as PCE (AVJ 1997).

As it can be seen from table 3.1, the use or production of several of the priority substances are less than a few tons per year. The production amount is probably distributed to 1-2 sites in Denmark, whereas the amount used in Denmark should be distributed to several sites, indicating that the amount used on a site can be very low. It is therefore expected that several of the priority substances will not automatically be included in investigation, as common practice is today, and thus potentially poses a risk of non-compliance with the EQSs. As the amount of substance used per year often is low, it is expected that any risk of non-compliance with EQSs will be very local.

3.3.5 Identification of substances of concern regarding quality standard scenarios

A comparison of GQS and the EQSs for Inland surface waters proposed by the Commission is listed in table 3.6. As mentioned earlier the EQS for "Other surface waters" are mostly the same as EQS for "Inland surface waters", but for some substances the EQS for "Other surface waters" are the lowest. However the conclusions based on table 3.6 will not be changed when using "Other surface waters" instead of "Inland surface waters". The following principles have been used:

• GQS/EQS ratios are calculated.
   
• If EQS is smaller than GQS (GQS/EQS >1), this indicates that there is a risk, and that a contamination with the priority substance is not detected through general administrative practice regarding soil and groundwater contamination.
   
• If EQS is larger or equal to than GQS, is it assumed that a contamination with the priority substance is detected and handled through general administrative practice.

Table 3.6
A comparison of GQS (Ground water quality standard) and EQS (Environmental quality standard for indland surface waters) proposed by the Commission.

It appears from table 3.6 that 18 out of 41 of the substances have EQS larger than GQS. It is assessed that soil and groundwater contamination with these substances will be managed through the existing administrative system, and ensuring compliance with the EQSs will therefore not require further action to be taken by Denmark. However, it should be noted that sites located in vulnerable areas are usually prioritized higher than other sites in the existing administrative system. The substances are:

GQS/EQS smaller than 1:

• Alachlor
• Atrazine
• Benzene
• Chlorfenvinphos
• 1,2-Dichloroethane
• Dichloromethane
• Di(2-ethylhexyl) phthalate
• Diuron
• Isoproturon
• Lead + compounds
• Naphthalene
• Nickel + compounds
• Pentachlorophenol
• Simazine
• Trichlormethane
• Carbontetrachloride
• Tetrachloroethylene
• Trichloroethylene

For some of the priority substances is it assessed, that since the EQS is smaller than GQS, there is a risk that contamination with the priority substances will not be detected in the investigation, as they are managed under the present administrative system. This indicates that this does not exclude the possibility and need for further action to be taken in Denmark to ensure compliance with the EQSs. The substances are:

GQS/EQS larger than 1:

• Anthracene
• Cadmium + compounds
• Chlorpyrifos
• Endosulfan
• Fluoranthene
• Hexachlorobenzene
• HCH/lindane
• Mercury + compounds
• Nonylphenol
• Octylphenol
• PAH (benzo[a]pyren)
• PAH (benzo[b + k]fluoranthen)
• PAH (benzo[g,h,i]perylen +indeno[1,2,3-cd]pyren)
• Trichloromethane
• Trifluralin
• DDT
• Cyclodiene pesticides: (aldrin, dieldrin, endrin, isodrin)

No Danish groundwater quality standards (GQS) have been established for the substances:

• Pentabromo diphenylether
• C10-13-chloroalkanes
• Hexachlorobutadiene
• Pentachlorobenzene
• Tributyltin compounds
• Trichlorobenzene

3.3.6 Substances of concern regarding practice on analysis

Based on an interview with Nis Hansen, Eurofins Danmark A/S, it is assessed that the major part of groundwater analyses are carried out in the framework of:

1. Water supply and unfiltered water monitoring
2. NOVANA groundwater monitoring
3. Groundwater investigations in connection with contaminated sites.

Comparison of analysis programmes for 1) and 2) is found in table 3.7. From this it appears that several priority substances are not part of the analysis programmes.

Table 3.7
Comparison of analysis programmes for 1) Water supply and unfiltered water monitoring and
2) NOVANA groundwater monitoring. If the substance is included in surface waters monitoring and/or if it is common practice to include the substance in groundwater investigations in connection with contaminated sites, it is noted in the comments

Eurofins Danmark A/S informs that at present, a few of the substances have no standardized method of analysis in Denmark.

Regarding 3) groundwater analyses in connection with contaminated sites, it is the impression of both Eurofins Danmark A/S and COWI that a large number of priority substances never or rarely form part of groundwater analyses. This applies to, among others, PAH's and heavy metals. This situation is assessed due to the fact that, generally, groundwater analyses are not carried out for substances with low mobility in the groundwater zone and that the other priority substances are not analysed unless they are assumed to constitute a significant part of the source contamination. This presupposes, other things being equal, that information on whether these substances have been used to a certain extent on the property, are available.

3.4 Types of contaminated sites of concern

Contamination of soil and ground water and run off of pollutants to surface waters can happen in many ways, in many places and can be distributed in many ways. Typical conceptual models for contamination and spreading of pollutants are described by, among others, Danish EPA (1996).

Please see chapter 2 regarding which type of sites and ways of dispersal are included in the project.

In this chapter, only properties of the site such as geology, hydrogeology, size of point source and distance to surface waters are included. Physical-chemical properties are only included in relation to an estimate of the initial concentration leaving the point source.

Contaminated water leaching from point sources is subjected to dilution when it flows towards the surface waters. The resulting concentration of contaminants in the surface waters is dependent on many parameters, see box 3.1, of which geology, recharge and travel distance are among the most important.

Box 3.1: Factors defining the concentration of contaminants leaching from a point source to surface waters

To make the assessments more functional, rough estimates of dilution factors in the aquifer in different scenarios are calculated in section 3.4.1. Dilution factors are here the reduction of the initial concentration at the point source to the edge of the surface water. In section 3.5, initial dilution of the contaminated groundwater in the surface water will be addressed.

As the framework of this study only permits an introductory approach, a simplified system with several assumptions has been chosen. When choosing the simplified system, the starting point has been to find general systems, which can describe a large part of Denmark and therefore gives a realistic indication of dilution factors.

A conceptual model for transport of contaminants from a contaminated site to surface waters appears from figure 3.2.

Figure 3.2:
Conceptual model for the dilution of contamination from point source to edge of surface water and initial dilution in the surface water. Abbreviations in the figure are described in the text in section 3.4.1.

3.4.1 Dilution of contaminated water leaching from point sources

Rough estimates of dilution factors in different scenarios can be deducted from mass balance equations. The approach and resulting dilution factors are described below.

The mass balance equation is defined for a given area and can be described by fluxes entering and leaving the specified area combined with the concentration of the contaminant in these fluxes. The concentration entering the area C_in is the concentration in the leaching water from the point source. The concentration leaving the area and entering the recipient is called C_out. The water flux out of the area is the sum of water fluxes entering the area, assuming a negligible storage of water in the area. Finally, the flux entering the area is the sum of three different fluxes; the flux leaching from the point source q_cont, the recharge q_recharge (infiltrating precipitation) and the groundwater flux q_gw entering the area upstream of the point source. The mass balance equation is then written as:

V_cont · C_in + V_recharge · 0 + V_gw · 0 = (V_cont + V_recharge + V_gw) · C_out

where generally V = q·A. The equation implies that there is no contamination of the groundwater and the infiltrating precipitation. The dilution factor F is then described by:

F = C_in / C_out = (V_cont + V_recharge + V_gw) / V_cont

The volumes are described as the fluxes multiplied with the contributing area for the individual flux:

F = (A_source · q_recharge + W_source · L_T · q_recharge + W_source · D_mixing · q_gw) / A_source · q_recharge

where the area of the point source is expressed by a length L_source and a width W_source. The travel distance from the point source to the recipient is called L_T and the mixing depth D_mixing.

The three terms in the equation depend on many different parameters and they contribute differently in different scenarios. According to the conceptual figure there are only two distinct scenarios depending on the pathway to the recipient. It is therefore assumed that lateral flow and transport through till and clayey soil is negligible compared to flow in higher permeable soils such as chalk and sand.

One scenario reflects a point source close to a receiving surface water body, where the contaminated water leaches to a secondary groundwater body. This body is in hydraulic contact with the receiving surface water body and has a limited and unknown size upstream of the point source. Thus, the dilution from the groundwater can be small and must be omitted from the mass balance equation when the contaminated water travels to the recipient in a secondary groundwater body. The dilution factor in a secondary water body will then only depend on the travel distance.

In the other scenario, the contaminated water has reached the primary groundwater body. In a sandy soil, it is assumed that there are no secondary groundwater bodies above the primary reservoir. In Denmark, this applies to the area west of "hovedstilstandslinien"^[1]. In the rest of the country, local secondary groundwater bodies are often found above the primary groundwater body. The contaminated water leaches to both water bodies, but is mainly transported to the surface waters through the primary reservoir. The primary groundwater body is mainly sandy layers, but it some areas the primary reservoir consists of fractured chalk.

In order to quantify every term in the equation, the following assumptions are made:

• The recharge q_recharge (L/T) is the same whether it is through the soil outside the point source or it describes the leaching from the point source. Thus, there is no pavement inside the area of interest.
   
• The transverse dispersion are neglected in the lateral direction
   
• The transverse dispersion in the vertical direction is assumed to result in a mixing depth of 0.25 m below the point source. The depth of the mixing zone increases with the travel distance, and it is assumed that the depth of the mixing zone is 10 times greater than the initial depth at a travel distance of 100 m. These assumptions are based on experience from the field and from calculations in JAGG.
   
• The area of the point source A_source is described by a length L_source and a width W_source. Because the transverse dispersion in the lateral direction is neglected, the water balance is reduced to a two dimensional system, the width can remain unknown. The length of the point source L_source is assumed to be 10 m.
   
• The groundwater flux into the system is described by Darcy's equation, thus the flux is expressed by the potential gradient over the travel distance multiplied by the hydraulic conductivity of the soil.
   
• The thickness of the reservoir is greater than the mixing depth for all travel distances.
   
• It is assumed that within the first 100 m from the point source, the primary part of the transportation of contaminants happens in the secondary groundwater body. Beyond 100 m from the point source the major part of the transportation of contaminant happens in the primary groundwater body.
   
• If there is a secondary groundwater body above the primary reservoir, the concentration entering the primary reservoir is reduced by a factor 10.

Based on these assumptions, dilution factors can be estimated for different geographical and geological settings. The involved parameters vary across the country and with the hydrogeology present at the actual site of interest. The parameters are, however, assumed to vary within the intervals listed in table 3.8 below.

Table 3.8:
Parameter values used in the water balance equation

By combining the parameters, a dilution factor F can be estimated. The dilution factor depends on the travel distance from the point source to the recipient and the four different scenarios based on variation in the pathway and in the geology.

Table 3.9:
Estimated dilution factors F

It can be seen from table 3.9 that within the first approx. 100 m from the point source, the dilution factor is often no more than 20.

At a distance of more than 100 m from the point source, the dilution factor is typically more than 100 and more than 1,000 at a distance of more than 1,000 m.

3.4.2 Dilution trough drainage systems

As stated in chapter 2, the focus in this report is on leaching of contaminated groundwater from a point source to surface waters via primary or secondary groundwater bodies. It has been chosen not to include leaching via drainage systems, that is drainage systems leading directly to surface waters such as land-drain, perimeter drain etc. The reason for this is further explained in this section.

Leaching of contaminated water via draining systems can potentially be dominating in areas near surface waters. As it will appear from section 4.1.1, areas near to surface waters are defined as areas closer than 100 m to inland surface waters and closer than 500 m from coastal waters. In areas close to surface waters, the leaching of contaminated water primarily happens through the secondary groundwater bodies, where the dilution generally will be relatively limited.

If the leaching happens through drains, the dilution in the groundwater bodies will be marginalized. A certain dilution is expected in the drainage system as the draining effect often covers an area which is larger than the area of the point source. The expected dilution in the drainage system is assessed to be of the same magnitude as the dilution in the secondary groundwater body.

In traditional cases of soil and groundwater pollution, leaching through drainage systems is generally considered to be, environmentally speaking, a more vulnerable way of spreading contaminants. This is due to the fact that the amount of sorption and degradation of contaminants is supposed to be higher in the groundwater body than in the drainage system. This is again based on comparison of retention time in drainage systems and groundwater bodies respectively.

In this report, it has been chosen to examine leaching of contaminants as an overall view on conservative dilution. The effect of sorption and degradation of contaminants is only included in the assessment for relatively immobile substances, and substances that are highly degradable and moderately mobile. These substances are considered to be of low risk regarding groundwater transportation, but also transportation via drainage systems will be limited for substances with these characteristic. The assessment of the leaching via drainage systems and via secondary groundwater bodies is therefore almost identical.

On this background, it has been decided not to examine leaching through drainage systems more detailed, but to assume that leaching through drainage systems regarding the effect on the surface waters can be covered by the description of dilution in the groundwater bodies near surface waters.

3.5 Substances constituting a risk of exceeding EQSs

Based on the result in section 3.1-3.4, an overall assessment of substances constituting a risk of exceeding the EQSs is carried out.

3.5.1 Relevant substances

For every substance, an assessment of whether the substance is relevant regarding the objective of this study is carried out. Substances are screened out if they are either not used or produced in Denmark, if the physical/chemical characteristics will not lead to spreading to the surface water or if the EQS is larger than the GQS. In table 3.10 below, an assessment of the substances is summarized.

As shown in table 3.10, five substances have not been screened out. These are: HCH, nonylphenol, octylphenol, tributyltin compounds and trichlorobenzene.

The five mentioned substances will be examined in the following chapters. In table 3.12, an assessment of the typical types of contaminated sites for the five substances is listed.

Table 3.10
Assessment of the 41 substances under the Water Framework Directive based on the principles described in chapter 3. 1: As endosulfan has only been used in very small amounts (2 tons/year), presumably on very few locations and has only been produced at one site in Denmark, it has been screened out.

²: The hazardous substances hexachlorobenzene and hexachlorobutadiene are screened out because they have not been used in Denmark. he hazardous substances hexachlorobenzene and hexachlorobutadiene are screened out because they have not been used in Denmark.

³: Priority Hazardous substances antracene, pentabromo diphenylether, cadmium and compounds, mercury and compounds pentachlorobenzene and PAH have been screened out based on their physical and chemical properties.

As shown in table 3.10, 9 substances were screened out solely based on comparison of GQS and EQS. However for sites located in some areas without groundwater resources (less vulnerable areas), the GQS are not necessary used in risk management. These less vulnerable areas are mostly located near or in coastal areas. Therefore water quality standards (WQS, from Statutory Order 921) have often been used instead of GQS.

Table 3.11 gives a comparison of WQS and EQS for the 9 substances. For most of the substances the EQS is identical with or larger than the WQS. Only pentachlorophenol and trichloromethane have an EQS smaller than the WQS. Therefore these two substances will be examined in the following chapters along with five that were singled out (see table 3.10).

Table 3.11:
Estimated need for dilution for the 9 substances that were screened out solely based on comparison of WQS and EQS.

3.5.2 Need for dilution to comply with the EQS

When looking at the spreading of contaminants in the groundwater body, the starting point is the concentration in the leaching water from the point source C_in. As free phase pollution is marginalized in this study the maximum concentration of interest is the solubility. Generally, the initial concentration in the point source does not reach the solubility. Based on the experience in COWI, it is estimated that the maximum concentration in the leaching water from the point source as a maximum is approximately 75 % of the solubility and. More realistic is C_in 10 % of the solubility, this value will be used unless other experience is inconsistent with this assumption.

In table 3.12 estimations on the leaching concentration Cin are summarized together with an estimate on the need for dilution, as both dilution in the groundwater body and initial dilution in the surface water are necessary to ensure compliance with the EQS.

Table 3.12:
Estimated need for dilution for the five substances that were singled out and the two additional substances (pentachlorophenol and trichloromethane, see section 3.5.1). The estimated leaching concentration Cin from point sources is compared with the EQS1.

¹: Cin is 10 % of the solubility.

It is seen from table 3.12, that the need for dilutions to comply with the EQSs is high, especially, for HCH, tributyltin compounds and trichlorobenzen. The results will be discussed further in the next chapter.

3.6 Phase out of hazardous priority substances

In section 3.5.1, an assessment of all 41 substances including the 13 hazardous priority substances (PHSs) has been carried out. Substances are screened out if they are either not used or produced in Denmark, if the physical/chemical characteristics will not lead to spreading to the surface water or if the EQS is larger than the GQS. The assessment is summarized in table 3.10.

An assessment of the priority hazardous substances (PHS) also needs to be carried out regarding the cessation of losses to the environment. The assessment is almost the same as in chapter 3.5.1. Substances are screened out if they are either not used or produced in Denmark, or if the physical/chemical characteristics implies that spreading to surface waters will not take place.

As seen in table 3.10, hexachlorobenzene and hexachlorobutadiene are screened out because they have not been used in Denmark. As endosulfan has only been used in very small amounts (2 tons/year), presumably at very few locations, and has only been produced at one site in Denmark, it has also been screened out. Anthracene, pentabromodiphenylether, cadmium and compounds, mercury and compounds pentachlorobenzene and PAH are screened out based on their physical and chemical properties. It is believed that none of these substances will be appear in surface waters due to losses from contaminated soil or groundwater.

^[1] main ice limit

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Version 1.0 February 2009, © Danish Environmental Protection Agency