Establishing Threshold Values for Groundwater

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

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

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

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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

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WFD Groundwater body
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• GWB Delineation
• GWB characterisation
• Risk assessment and Threshold values
• References

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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.

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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

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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,

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The Conceptual Model
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• GWB Delineation
• GWB characterisation
• Risk assessment and Threshold values
• References

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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

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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
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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
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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, )

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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?

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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

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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

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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

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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.

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4. Methodology to derive TV

• 4.1 Preliminary steps

Source A. Blum WG C meeting Berlin 07
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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
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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
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Reporting
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• GWB Delineation
• GWB characterisation
• Risk assessment and Threshold values
• References

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References CIS Guidance documents
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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