Groundwater Quality Data Base (GQDB)
The following types of information were collected: written sources (literature references, documents and web pages) and data sources (groundwater quality data sets). The first were collected by means of a questionnaire and were processed in a data base (RefBase), while the latter were collected via the questionnaire and by individual approach to the partners and stored in the Groundwater Quality Data Base (GQDB). The statistical analysis of the GQDB is a first attempt to compare a large range of groundwater data from EU partner countries on the level of individual aquifers.
The data sets were designed to cover the main hydrogeological regions of Europe, and may cover both non altered and polluted aquifers. This approach to data collection is the same as in the BaSeLiNe project, but the existing set of 24 reference aquifers from BaSeLiNe was extended to 63.
Statistical analysis, selection of parameters, and graphic presentation
The overall goal of the statistical analysis was to summarise the groundwater data effectively for inorganic components, and were applied to three data levels:
u all data - no grouping, all data sets pooled
u the group level - data sets grouped on aquifer lithology: carbonate, hard rock, sandstone or unconsolidated material
u the individual level - data considered as the original data set of the individual aquifer
Data were used to produce cumulative frequency plots per component for the valid cases of level 2 and 3 data sets. The observations below DL were not plotted, although were labelled as a negative number and therefore could still be included in the percentile statistics.
BACKGROUND CRITERIA FOR THE IDENTIFICATION OF GROUNDWATER THRESHOLDS
BRIDGE BRIDGE
02 /2007 Marc h-April
BRIDGE
SURVEY OF REPRESENTATIVE GROUNDWATER POLLUTANTS Chemical status of groundwater. Geochemistry
BRIDGE Web Page http://www.igme.es/Bridge
©Albufera de Valencia
Working Group Packages: Main outputs, conclusions and recommendations
The BRIDGE project intends to develop a common methodology, intended for possible use by Member States, on “how to derive groundwater thres- holds”. The different objectives of BRIDGE are:
u to evaluate and assemble scientific outputs to set out criteria for the assessment of the chemical status of groundwater. These criteria are data for characterisation of natural and anthropogenic pollutants, para- meters indicative for pollution, data for characterisation of groundwater bodies as hydrologic and hydro-geological parameters,
u to derive a plausible general approach, how to structure relevant criteria appropriately with the aim to set representative groundwater threshold values scientifically sound and defined at national river basin dis- trict or groundwater body level,
u to check the applicability and validity of this approach by means of case studies at the European scale, u to carry out an environmental impact assessment taking into account the economic and social impacts.
Project objectives
State of the art report
A state of the art report, including information about the geochemical and related aspects (ecotoxicology, analysis, monitoring and sampling), was produced. It deals with the occurrence and behaviour of potentially harmful natural and anthropogenic substances in groundwater environments, the impact on aquatic, terrestrial as well as groundwater ecosystems, and analytical, monitoring and sampling practise as far as it has an impact on deducing threshold values for groundwater bodies. The report focuses on three main groups of substances: the WFD pollutants, the 33 EC priority pollutants and the emerging substances.
To illustrate the relationship between major groundwater composition and hydrogeology a case-study from Germany
was made. The hydrogeological units chosen for the description of the major groundwater environments take into account two major factors influencing groundwater composition: Petrographic properties of the vadose zone and the groundwater bearing rocks and physical hydrogeology of the geological setting.
A state-of-the-art survey of the hydrogeochemistry of inorganic groundwater pollutants defined by the WFD and the Priority Substances List has been included. It also presents a selection of groundwater data for 60 reference aquifers situated all across Europe. The inorganic substances described are with one exception on the WFD and/or the priority list. The exception is aluminium, which is likely to be added to the Priority List in the near future.
The Groundwater Directive (GWD) calls for the establishment of threshold values for pollutants considering the behaviour of each substance. It requires knowledge of the intrinsic properties of pollutants but also of hydro-geological and biogeochemical characteristics of media. Then, a good conceptual understanding of the water bodies involved including the interactions with surface water and dependant terrestrial ecosystems is needed.
Typology of the aquifer
Groundwater bodies have been delineated using different methods and classification criteria. As a result some GWB may include several aquifers leading to hydro-geochemical heterogeneity. It points out the need to consider aquifer properties. A common basis for description of hydro- geochemical characteristics of groundwater, an “aquifer typology”, to be used in thresholds derivation is proposed. It
Locations of reference aquifers. Red circles indicate data fromBaSeLiNe green circles indicate new data added in BRIDGE
Cumulative frequency plot for arsenic. The vertical line represents the maximum admissible concentration of arsenic in drinking water
Factors influencing groundwater quality (Kunkel et al., 2004)
Ammonium (a) and iron (b) versus nitrate. Vertical lines separate aerobic and anaerobic groundwater using the 2.5 mg/l NO3 threshold. The horizontal lines separate (a) high ammonium waters or (b) high Fe waters from lower concentrations.
STUDY OF GROUNDWATER CHARACTERISTICS
Hydrogeological and hydrogeochemical characteristics of European aquifers relevant for
determination of threshold values in groundwater
is composed of 2 levels of parameters. Primary ones relate to the origin of compounds (a basis for determination of the Natural Background Level) and they lead to the definition of 10 basic units. Secondary parameters relate to processes (contribute to explain the variability of groundwater composition) and include hydrodynamics, redox conditions, geological age and particular occurrences within aquifer material such as organic matter, oxides and sulphides minerals.
Response time-lags of aquifers
Dispersion and persistency of pollutants are linked with the residence time of groundwater. Increasing residence time favours dilution of pollutants but also their persistency.
However, many European aquifers have considerable response time-lags to anthropogenic inputs, which indicates a need for anticipation. The response time-lags of aquifers to anthropogenic input are not only due to transfer within the groundwater but also within the vadose zone. Relative low attention has been paid on transfer time through vadose zone compared to that in groundwater.
Dilution during the interactions between
groundwater and its associated surface waters and terrestrial ecosystems
Many surface water features rely in part on groundwater.
Baseflow is a key parameter in potential dilution of pollutants and depends on the lithology of the groundwater body, although many other variables also have influence, including recharge, surface cover, drift, land use and climatic conditions and as a result the issues are too complex and data are scarce to propose any range of baseflow contribution to surface water applicable to European scale.
Attenuation
Attenuation includes physical, chemical or biological processes which may affect persistency of pollutants. When degradation is limited in the aquifer itself, it may nevertheless be important in the riparian and hyporheic zones, or within the GWDTE. Studies have been carried out at local scale, but difficulty lies in the catchment’s scale. It is important to understand the longevity and sustainability of processes along with the potential for eventual re-mobilization of pollutants within riparian, hyporheic zones and GWTDE.
Possible controversy on pollutant origin
The origin of a pollutant may be natural, whereas its concentration is impacted by anthropogenic activities.
Modifications of water-rock interactions take place in aquifer following either the input of some pollutants or any change of hydrodynamics leading to an increase of pollutants concentrations.
Concluding remarks
Understanding the nature of groundwater is a key challenge in derivation of threshold values, and it is essential for appropriate investigation if a threshold value is exceeded at one or more monitoring points before deciding on the chemical status. The proposed aquifer typology provides a general framework for understanding the natural chemical composition of groundwater and the processes that affect the fate and transport of pollutants. However, it is vital to understand the heterogeneity of groundwater, including the characteristics due to variability of processes and strengthened by the residence time of groundwater. The Groundwater Directive states that thresholds values may be amended, which is a crucial point as there is a clear need of further research on many points such as transfer time within the vadose zone and the extent of processes within riparian and hyporheic zones.
The proposed tiered approach allows the targeted use of resources both in assessment and remedial measures. Status assessment has to take into account that the chemical quality of groundwater as well as fate and transport are determined by many factors, where lithologic properties of rocks, regional
hydrological and hydrodynamic conditions and hydrogeochemical processes are of major importance. Thus status assessment needs to go beyond quality assessment and consider attenuation criteria.
European aquifer typology for NBLs – map (Research Centre Jülich,)
Residence time of groundwater in European aquifers
CRITERIA FOR ENVIRONMENTAL THRESHOLDS AND METHODOLOGY TO DEFINE A GOOD STATUS
Procedure for status determination and threshold setting
u Assessing the Natural Background Level (NBL) Natural Background Levels can be defined following a hierarchy of possible options. BRIDGE has referenced NBLs from national studies if no groundwater quality data are available (only hydrogeological units of a specific groundwater body can be described). If a limited set of data is available a second option to determine NBLs is based on a pre-selection method. When a broad set of quality data is available, the third option to estimate NBLs is to apply scientifically sound methods (e.g. hydrochemical simulations, component separation, etc.).
u Selection of the Reference Quality Standard Generic reference values selected according to receptors are to be used. If no European standards exist, national reference values can be used. For substances without reference values a survey and evaluation of human toxicity or ecotoxicity data will be necessary. The evaluation of these toxicity data should again be based on and refer to either agreed European procedures or national agreements.
Once identified the receptor and determined the NBL the tiered method may begin to be employed. It relies on a series of steps in which the impact on the receptor is defined with increasing precision. In the early Tiers the concentration of pollutant in groundwater is compared with NBL and receptor based standards (i.e. drinking water standards) whereas in the later Tiers the possible mitigating effects of dilution of the pollutant with water (i.e. surface water) and the attenuation due to (bio)geochemical reactions is considered. It is not intended that every groundwater body need be assessed at every Tier.
u Tier 1: NBL. For those pollutants that are synthetic the appropriate NBL is zero
u Tier 2: The receptor based quality standard, which refers to existing relevant standards or reference values.
Regarding groundwater as a receptor an intermediate step (2a) is introduced to Tier 2, where NBL are used as the generic environmental criteria
u Tier 3: Allows account to be taken of the proportion of the pollutant mass flow due to the groundwater. There may not
be a single source of water. If the main source of pollutant is from surface water drainage then the groundwater status should not be penalised unnecessarily. The concept of the Dilution Factor (DF) is intended to provide a mechanism where the proportion of the impact that may be ascribed to groundwater pollution can be taken into account.
u Tier 4: This final Tier allows consideration of any attenuating processes that may occur to diminish the impact in the final receptor from pollutants in the groundwater. The concept of the Attenuation Factor (AF) is intended to provide a mechanism where the proportion of the impact that may be ascribed to groundwater pollution can be taken into account.
The comparison of pollutant within each Tier determines whether it is worthwhile progressing to the next Tier, which implies increased data needs and cost of assessment.
Determining a threshold for a surface water receptor Expert judgement might be needed for groundwater bodies with long groundwater residence times, to define whether it is appropriate to apply a threshold value for the surface water receptor in the recharge zone, or to limit the compliance regime to areas of limited flow times close to the discharge area.
Determining a threshold for a dependent terrestrial ecosystem
The lack of legal and scientific background made it impossible to develop a methodological approach on how to determine groundwater thresholds for dependent terrestrial ecosystems.
Determining the threshold for groundwater
Necessarily the issue of understanding the legal system established by the WFD and the GWDD needs to be addressed and clarified at the administrative level under the Common Implementation Strategy of the WFD.
Groundwater as a resource
To assess status, threshold values need to be used to evaluate monitoring data at each single monitoring station, as well as applied to aggregated and weighted results across
Flow chart for derivation of threshold values
Two aggregation methods for calculating the percentage of monitoring points not exceeding a quality standard or TV
the groundwater body. Therefore threshold values determined under these elements are not receptor-oriented but try to control the average concentration of substances of all stored groundwater. To address saline intrusions again specific considerations are necessary.
Groundwater ‘itself’
BRIDGE discussed alternative options for the derivation of Tier 2a values where no suitable standard exists, which is based on the NBL of groundwater in a body. By the results of the case studies the finally described option is felt to be a pragmatic approach referring to NBLs as the only available sound environmental criteria but also recognising that a policy of ‘zero’-pollution is not possible.
Groundwater as an ecosystem
In contrast to status objectives for surface waters the WFD does not give recognition to an ‘ecological status’ of groundwater bodies. Furthermore the knowledge of the ecology of groundwater and aquifers is considered as far too basic to allow the development of scientifically sound values based on sub-surface ecology.
Remarks regarding the definition of compliance regimes
A sound concept of status assessment needs to build its compliance regime as a complementary approach to the implemented monitoring concept and considerations relevant for threshold value determination.
Location and type of investigated groundwater bodies
The investigated groundwater bodies are located in 12 of the 25 eco-regions for rivers and lakes defined in the WFD, and they cover most of the important aquifer typologies in Europe.
Hence most of the major climatological and hydrogeological settings are represented. They are not necessarily representative for the general or average conditions in the eco-region to which they belong, and not all of the investigated groundwater bodies interact significantly with an aquatic or terrestrial ecosystem.
Summary of performed evaluations
The BRIDGE case studies cover carbonates, volcanic rocks, crystalline rocks, sand and gravel, and sandstone. Chalk, schist and marls, evaporites and clays are not covered.
Overall conclusion
u The proposed method for TV derivation has been tested in 14 case studies representing most of the major European aquifer typologies and most of the ecoregions defined in the Water Framework Directive. It is simple to use and seems a suitable tool for groundwater status evaluation, and hence for protection of human health and groundwater, as well as groundwater dependent ecosystems
u The tiered approach was found appropriate, and the application of both the natural background levels and relevant reference values for groundwater itself and/or reference values for groundwater dependent ecosystems for derivation of groundwater threshold values, was found to be logical, suitable and easy to understand and apply. It
REPRESENTATIVE SITES / WATER BODY STUDIES AND COMPLIANCE TESTING
Application and evaluation of a proposed methodology for derivation of groundwater threshold values – a case study summary report
Location of the 14 groundwater bodies selected for the representative site case studies
List of investigated groundwater bodies (GWB’s). The ”Ecoregion for rivers and lakesin which the GWB is located, and the ”Ecoregion for coastal waters” to which their associated river basin discharge is also indicated
Steps in the economic analysis in the WFD and corresponding time path (modified from the WATECO Guidance Document)
Location and type of investigated groundwater bodies
u Upper Rhine valley quaternary aquifer, France u Scheldt basin in the Netherlands
u Lahti, Finland
u Aveiro Quaternary Aquifer in Portugal u Riga, Latvia
Overall conclusions and key recommendations u One of the main objectives of BRIDGE is to develop, apply
and test economic methods for the identification of economically efficient groundwater threshold values.
u Economic criteria start playing a role after the threshold values have been set, namely in the design of practical groundwater management measures.
u The integrated environmental-economic impact assessment provides the basis for the evaluation of possible disproportionate costs but not the sole decision- making criterion. The definition of ‘economic threshold values’ or benchmarks for the assessment of disproportionate costs is subjective and political.
u In order to be able to evaluate and assess whether the economic costs of reaching environmental groundwater threshold values are disproportional, an important step is to evaluate the cost and effectiveness of possible practical management measures to reach these threshold values u In the WP5 case studies the researchers and analysts are
unable to judge whether the estimated total costs are disproportional compared to their economic benefits.
u An important role of the economic analysis in WP5 is to estimate the economic value of sustainable groundwater resources management by including the value attached to groundwater protection and preservation for the sake of the resource itself.
u The economic value of the non-market benefits is does, however, require increasing expert participation as
well as data amounts and understanding of the system, to move to tiers where dilution and attenuation in the groundwater bodies are taken into account.
u It is crucial that the natural background levels and reference values are derived properly, as the derived threshold values will be sensitive to both. Hence, a sound understanding and delineation of aquifer and hydrochemical typologies are of great importance.
u The final selection of a method for derivation of threshold values as a management tool for the protection of the environment and human health, includes a political component, and has also to some extent to take into account socio-economic as well as environmental and health impact assessments and considerations. The proposed method is found to acknowledge this fact.
u The derivation of groundwater threshold values based on natural background levels and reference values such as environmental quality standards for dependent ecosystems or for groundwater itself is in its infancy, and research is strongly needed to develop and apply this concept.
Percentile plots of estimated NBLs at the 90th percentile and derivedTVs for selected substances in all investigated groundwater bodies
ECONOMIC AND SOCIAL COSTS LINKED TO THE ESTABLISHMENT OF GROUNDWATER THRESHOLD VALUES
Socio-economic assessment
measured in terms of public willingness to pay for groundwater quality improvement. Although economic use values dominate the economic values found for different groundwater threshold values, there is substantial non-use or existence values for groundwater protection in all case studies, providing support for the receptor-based approach advocated in BRIDGE.
u For the purpose of measuring public perception and values of groundwater quality threshold values, a ‘groundwater quality ladder’ was developed and tested in the public surveys in the WP5 case studies, reflecting different use and non-use related economic values of groundwater quality.
u Local stakeholders willingness to pay for different groundwater quality threshold values can be used as one of the possible ‘economic’ threshold values for disproportional costs, accounting for their ability to pay.
u Risk and uncertainty are key concepts in the environmental and economic assessment of different groundwater quality
threshold values, supporting the adoption of an ‘adaptive management’ approach as in the overall BRIDGE ‘tiered approach’.
u Economic criteria are expected to be an integral part of the actual adoption and implementation of any groundwater monitoring and management plan.
u Assessing the environmental impact of programs of measures on water quality with some degree of confidence will be one of the most important challenges in the implementation of the new European Groundwater Directive.
u The effects of most measures are evaluated in terms of their emission reduction potential, not their impact on water quality measured through the change in pollutant concentration levels basin-wide. More research is needed here in scientific models built with the help of expert judgment to better understand this relationship in time and space.
BRIDGE Disemination activities
A. CONTRIBUTIONS IN SCIENTIFIC EVENTS
1. Common Forum on Contaminated Land – Vienna (Austria), May, 12-13, 2005 (UBA-A). BRIDGE project presentation
2. Second European Conference on Natural Attenuation, Soil and Groundwater Risk Management - Frankfurt am Main (Germany), May, 18-20, 2005: Science-policy integration needs preparing common approaches to manage groundwater resources in Europe (poster) (UBA-A)
3. VI Simposio del Agua en Andalucía - Sevilla (Spain), June, 1-3, 2005: Criterios para la identificación de valores límite de conta- minantes en agua subterránea. Proyecto BRIDGE (IGME) 4. EWRA 2005 (European Water Resources Association) – Men-
ton (France), September, 7-10, 2005: Presentation of the BRIDGE Project - Background Criteria for the Identification of Groundwater Thresholds (BRGM and WP chairs)
5. International Conference “Vulnerable Aquifer Preservation: Com- paring European Experience” – Perugia (Italy), 8th September 2005 “BRIDGE – Background Criteria for the Identification of Groundwater Thresholds” (UBA- A)
6. The Central European and European Union Standards on the Assessment of the Industrial and Mining Environmental Pollution – Warsaw (Poland), September, 21-24, 2005: Criteria for envi- ronmental pollution of industrial and mining areas assessment in Spain. The European BRIDGE Project (IGME)
7. European Conference on Water Framework Directive…the baseline. The Geological Society - London (United Kingdom), September, 22nd, 2005. Implementing the Water Framework Directive and characterising baseline groundwater conditions.
Work progress in Spain and BRIDGE Project (IGME)
8. CONSOIL 2005 – Bordeaux (France), October, 3-7, 2005 (Lec- ture Session A.1: Policy on Contaminated Land Management):
Background Criteria for the Identification of Groundwater Thresholds (UBA-A and BRGM)
9. IAH-Conference (International Association of Hydrogeologists - Alicante (Spain), October, 4-8, 2005: Background Criteria for the Identification of Groundwater Thresholds. Presentation of the BRIDGE Project (IGME).
10. Workshop on Groundwater Bodies in Europe and Adjacent Countries – Berlin (Germany) , October, 25-26, 2005; Natural background values and threshold values – the European BRIDGE Project (HLUG)
11. Meeting of the Slovene section of the International association of Hydrogeologists (IAH) – Laibach (Slovenia), November, 22nd, 2005: Implementation of the EU Water Framework Directive (WFD) in Austria, Groundwater quality aspects – procedures applied and current state” (UBA-A)
12. Seminar on Groundwater Modelling - Water Framework Direc- tive INFRA 21268, 17-20 January 2006, Sandanski (Bulgaria) organised in co-operation with Executive Environment Agency of the Ministry of Environment and Water, Bulgaria; with financial support of TAIEX. Bridge Project presentation (Executive Envi- ronment Agency)
13. AQUAinMED International Congress “Ground Water in Mediterranean Countries” 24 - 28 April 2006 Malaga (Spain).
Organised by IGME, Madrid School of Mines and Málaga University (IGME)
14. The European Groundwater Conference held during the Austrian Presidency, 22 – 23 June 2006 Vienna, AUSTRIA.
Organised by Umweltbundesamt (Federal Environment Agency) of Austria (UBA-A-BRGM)
15. Groundwater- present status and future task XXXIV Congress of IAH, October 9 - 13 Beijing (CHINA). Organised by IAH and the Ministry of Land and Resources of China (IGME)
16. Final BURVAL Conference – Hannover (Germany), November 29-30, 2006: Towards sustainable groundwater management – Policy Aspects and Environmental Thresholds (UBA-A) 17. HERACLES Workshop - Derivation methods of soil screening
values in Europe (Jointly organized by the Joint Research Cen- tre and DG Environment), Ispra (Italy), February, 5-6, 2007:
BRIDGE – Proposals to derive Environmental Groundwater Threshold Values (UBA-A)
18. WFD Lille 2007 – Water Status Monitoring of Aquatic Ecosys- tems in the Context of the Water Framework Directive; Lille (France), March,12-14, 2007: Establishing Environmental Groundwater Quality Objectives (UBA-A)
© BRIDGE.BACKGROUND CRITERIA FOR THE IDENTIFICATION OF GROUNDWATER THRESHOLDS April 2007 - NIPO: 657-06-009-6 D.L.: M-24621-2006 Design and Edition: IGME
Project identification
6FP: Priority 8, Scientific Support to Policies Contract Nº: 006538 (SSPI)
Duration: 24 months Start Date: 1st January 2005
Budget of the project:
Total budget ... 2.963 M€ EC contribution ... 1.877 M€ Co-ordinator:
Anne-Marie Fouillac (Fr) [email protected] Co-chair:
Dietmar Müller (At)
Composition of the Consortium
BRIDGE Disemination activities
19. Meeting organised by the Danish Engineering Association (IDA), Copenhagen, March, 26, 2007 “The European Groundwater Directive, contents and implementation”: Derivation of environ- mental thresholds for pollutants of groundwater bodies, Descrip- tion of the methodology for threshold derivation elaborated in the BRIDGE project (UBA-A)
B. PRESENTATION TO ENVIRONMENTAL NATIONAL AUTHORITIES
1. Information about BRIDGE Project and discussions within the Flemish Government with OVAM (= Flemish Waste Agency) and AMINAL (Flemish Administration for Environment, Nature Land and Water Management) (VITO)
2. Preparation and presentation of information about BRIDGE pro- ject to Ministry of Environment and to Government of Republic of Lithuania in relation to the project “Impact assessment for the implementation of the directive of the EP and of the EC on the protection of groundwater against pollution (COM 550) (LGT) 3. Information about AETS and BRIDGE sent to: Innovalis Aquitai-
ne - Agence Régionale de Soutien à l’Innovation. Bureau Euro- pe Rémi VIGNES Centre Condorcet (AETS)
4. Information about BRIDGE achievements to the Ministry of Environment of Spain in a conference dedicated to the Ground- water Directive implementation organised in Madrid in January 2007
5. Efforts to promote the general results of BRIDGE and introduce the interested public to the methodology will be continued dur- ing 2007 by presentation at national meetings (see e.g. invitation to the Danish national meeting, March, 2007).
C. INFORMATION TO PROJECTS RELATED TO OTHER DIRECTIVES
1. The results have been communicated to a related policy support project concerning soils (ENVASSO - approaches for soil moni- toring and the assessment of soil status) and will be further com- municated and discussed towards ongoing activities related to the Soil Thematic Strategy (e.g. see HERACLES-Workshop, Ispra, February 2007).
D. INFORMATION PUBLISHED BY TECHNICAL MAGAZINES
1. Groundwater eNews. It is the e-mail news service of the Interna- tional Association of Hydrogeologists and is produced approxi- mately every two months. In the July 2005 issue, under the title of EU Groundwater related research projects, information about BRIDGE were provided to the members of IAH. IAH has over 3,500 members in 135 countries
