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Establishing Threshold Values for Groundwater

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Aquifer' means a subsurface layer or layers of rock or other geological strata ... data are available, then use the BIDGE aquifer typology www.wfd-bridge. ... – PowerPoint PPT presentation

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Title: Establishing Threshold Values for Groundwater


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 2013and 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 (
     criterias 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 - TC 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 gt 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. Methodology to derive TV
  • 4.1 Preliminary steps

Source A. Blum WG C meeting Berlin 07
22
4. Methodology to derive TV
4.2 Methodology
  • Remarks
  • 2 types of criteria
  •  Saline and other intrusion  criteria to be
    linked with NBL

Xi
Source A. Blum WG C meeting Berlin 07
23
4. Methodology to derive TV
  • 4.2 Methodology
  • Remarks
  • e to define by each Member State
  • Using a risk assessment
  • 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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