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Establishing Threshold Values for Groundwater

Establishing Threshold Values for Groundwater. Johannes Grath Andreas Scheidleder 26 June 2007. Contents. GWB Delineation GWB characterisation Risk assessment and Threshold values References. GWB Delineation GWB characterisation Risk assessment and Threshold values References.

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Establishing Threshold Values for Groundwater

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  1. Establishing Threshold Values for Groundwater Johannes Grath Andreas Scheidleder 26 June 2007

  2. Contents • GWB Delineation • GWB characterisation • Risk assessment and Threshold values • References

  3. GWB Delineation • GWB characterisation • Risk assessment and Threshold values • References

  4. WFD - Definitions Definitions in WFD Article 2 • ‘Groundwater’means all water, which is below the surface of the ground in the saturated zone and in direct contact with the ground or subsoil. • ‘Aquifer’means a subsurface layer or layers of rock or other geological strata of sufficient porosity and permeability to allow either a significant flow of groundwater or the abstraction of significant quantities of groundwater. • ‘Body of groundwater’ means a distinct volume of groundwater within an aquifer or aquifers= managing unit

  5. WFD – Groundwater body

  6. GWB Delineation • GWB characterisation • Risk assessment and Threshold values • References

  7. GWB characterisation & risk assessment WFD Article 5 1. “…for each river basin district…: • an analysis of its characteristic • a review of the impact of human activity on the status of ...groundwater … according to the Annex II … … completed 22 December 2004 …” 2. “… review/update 2013…and every 6 years thereafter.”

  8. CharacterisationRequirements in the WFD Annex II – Initial Characterisation • all Groundwater Bodies • … analysis … shall identify • location and boundaries of GW-bodies • pressures • diffuse + point sources of pollution • abstraction + artificial recharge • general character of overlying strata • directly dependent surface water- or terrestrial ecosystems  Basis for Risk Assessment

  9. CharacterisationRequirements in the WFD Annex II – Further Characterisation • Groundwater Bodies at risk – (Annex II, 2.2, 2.3) • Transboundary Groundwater Bodies – (Annex II, 2.3) • 2.2: …where relevant, information on • e. g.: Geological characteristics, units….. • Hydrogeological characteristics, conductivity, …. • … • 2.3: … where relevant • Points for abstraction • Abstraction rate, …

  10. The Conceptual Model

  11. GWB Delineation • GWB characterisation • Risk assessment and Threshold values • References

  12. Background Current activity of WG C Groundwater – Subgroup « Status compliance and Trends » • Mandate: TV paper • Article 3 of the GWD (« criteria for assessing groundwater chemical status ») • Based on BRIDGE outcomes • Environmental objectives of the GWD / Receptors to protect • Articles 3 and 4 (status assessment) • Surface water • Groundwater Depending Terrestrial Ecosystems (GWDTE) • Human uses • Article 5 (trends) • Groundwater « itself »  • (Surface water, GWDTE, Human uses) • Article 6 (prevent or limit) • Groundwater « itself »  • (Surface water, GWDTE, Human uses)  Full protection of groundwater

  13. Background Legal background: GWD (2006/118/EC) Main objectives and requirements • Groundwater Quality Standards (GW-QS) • Threshold values (TV) for: • Parameters causing a risk of failing 2015 objectives • Including NO3 and/or pesticides if relevant • Taking the minimum list into account The links between Article 3 and Article 6 Source: A. Blum; WG C meeting Berlin 07

  14. Background Required scale for deriving TV • 3 possible levels (article 3.2) • National, River district, GWB • Consequence: GWB = the smallest allowed scale for the TV to be reported in the management plan  GWB heterogeneity will have to be taken into account through intermediate values ( « criteria’s values ») and through the appropriate investigation Schedule and revision • Key dates (Article 3.5) • TV to be established by 22 December 2008 • TV to be published in the RBMP by 22 December 2009 • Revision (Article 3.6) Information to be reported in the RBMP Transboundary GWB Source: A. Blum; WG C meeting Berlin 07

  15. Identification of receptors • GW associated surface waters • Rivers, Lakes • Transitional, Coastal waters • GW-dependent terrestrial ecosystems and wetlands / mire / GW-fed fens • Human uses (drinking water, irrigation, industrial use, farming, …)

  16. Identify risk parameters for each receptor • Risk assessment as a basis • Surveillance monitoring provides a validation of risk assessment for rivers, lakes, and groundwater, coastal and transitional water, mires and identifies the parameters responsible for the risks. • Consider As – Cd – Pb – Hg – NH4 – Cl – SO4 – Trichloroetylene – Tetrachloroethylene – Electrical Conductivity (indicator) and determine if there is a risk or not. If yes, then these parameters need a threshold value • Other relevant Parameters?

  17. Reference (criteria values) • For depending surface waters (rivers and lakes) it is possible to use environmental quality standards for priority substances (draft directive EQS [COM(2006) 397 final] if no appropriate national EQS are available. • For mires it is possible to use local expert knowledge or to apply the EQS for aquatic ecosystems as well. • For drinking water, use the Drinking Water Standards (DWS). If treatment is already used: Use operational performance limit for existing or regionally usual treatment infrastructure. • For other legitimate uses: Dependent on use - Food-related use DWS, for non-food use suggest process operational needs determined on case-by-case • For saline and other intrusion: use the natural background values

  18. GW-contribution for the risk • Identification of connections (extent of interaction) – discharge/transfer of pollutants to the receptor • Analysis of hydrographs in water discharge monitoring stations - T°C – age of water (tritium), etc. • Use the existing experimental set up along the main rivers of Latvia to derive some values for groundwater contribution to surface water discharge • Expert knowledge on mires: phyto-sociology can provide some information on the groundwater contribution to the wetland • Calculate the amount of pollutants to be transferred from the groundwater to the receptor by considering dilution, attenuation effects to the receptor if available but also seasonal variations • Derive the maximum concentration allowed in the groundwater

  19. Natural Background level • Derive background levels for all groundwater bodies (shallow and deep groundwater) • If there is geochemical data available, separate pristine data from human influenced data. It is possible to use the BRIDGE methodology or a national methodology • If no geochemical data are available, then use the BIDGE aquifer typology – www.wfd-bridge.net to transfer background values from similar aquifer types in Europe to Latvian aquifers

  20. Threshold Value • Compare the maximum concentration allowed to the background level • Then this is a political decision • If the background value is below the maximum concentration, then the threshold value can be the maximum concentration allowed (current state of draft guidance paper => “minimum approach”) i.e. it is at the discretion of MS to set lower concentration levels (more strict) • If the background level is above the maximum concentration, • Either use background level as threshold value, which means no additional human pressure • Or use a threshold value above the background level to allow human pressure to some extent. Yet, this implies to reduce the contribution of other polluters to the receptor.

  21. 4.1 Preliminary steps 4. Methodology to derive TV Source: A. Blum; WG C meeting Berlin 07

  22. Select the relevant criteria Usage criteria Selection of legitimate uses which’s surface is significant compared to the whole surface of the GWB Environmental criteria Surface waters and wetlands Crops Drinking water Industry Others… Deriving a criteria’s value for each of the relevant criteria X2 X3 X4 X1= EQS*AF1/DF1 Identify the lowest criteria’s value Compare to NBL 4. Methodology to derive TV Remarks • 2 types of criteria • « Saline and other intrusion » criteria to be linked with NBL 4.2 Methodology Xi… Source: A. Blum; WG C meeting Berlin 07

  23. TV e NBL TV Most stringent criteria’s value NBL Case 1 Case 2 4. Methodology to derive TV 4.2 Methodology Remarks • e to define by each Member State • Using a riskassessment • MS can define lower TVs if relevant  Minimum approach to fit WFD/GWD objectives Source: A. Blum; WG C meeting Berlin 07

  24. Reporting

  25. GWB Delineation • GWB characterisation • Risk assessment and Threshold values • References

  26. References: CIS Guidance documents

  27. References: Draft CIS Guidance documents • Guidance on the application of the term „direct and indirect inputs“ in the context of the Groundwater Directive 2006/118/EC - draft • Guidance on Groundwater in Drinking Water Protected Areas –draft • Common methodology for the establishment of groundwater threshold values –draft • Groundwater chemical status - draft

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