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Groundwater protection strategy

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Approximately 2600 common water utilities in Denmark with total abstraction of ... Geological setting: Glacial deposits on a basement of paleocene chalk and marl. ... – PowerPoint PPT presentation

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Title: Groundwater protection strategy


1
Groundwater protection strategy
  • Troels Kærgaard Bjerre
  • Odense Water
  • GroPro International Conference
  • ATV JORD OG GRUNDVAND
  • KLARSKOVGAARD
  • 15. - 17. september 2008

2
Agenda
  • Odense Water
  • Background
  • Groundwater protection strategy of Odense Water
  • Conclusions
  • Perspectives

3
Odense
4
Facts and figures about Odense Water
  • Approximately 2600 common water utilities in
    Denmark with total abstraction of approximately
    400 mill. m³/year.
  • Odense Water is one of the biggest water utility
    with a abstraction permission of 13,8 mill.
    m³/year.
  • Groundwater abstraction on 7 wellfields.
  • 42 abstraction wells (25 to 100 m deep).
  • Geological setting Glacial deposits on a
    basement of paleocene chalk and marl.
  • Aquifers Glacial sand- and graveldeposits and to
    a small extend paleocene chalk.

5
Major threats towards the wellfields of Odense
Water
  • Quantitative threats
  • Urbanization
  • Environmental targets
  • Climate change
  • Qualitative threats
  • Pesticides
  • Chlorinated solvents
  • Other org. haz. subst.
  • Nitrate
  • Chloride
  • Hardness (Ca and Mg)
  • Arsenic

6
Why is groundwater protection a hot issue in
Denmark?
  • 99 of the drinking water in Denmark comes from
    groundwater!
  • The National Groundwater Policy of Denmark!
  • Action plans for groundwater protection!

7
The National Ground Water Policy of Denmark
  • Objectives
  • Production of drinking water should be based on a
    decentralized abstraction structure.
  • Protection against exploitation of groundwater.
  • Production of drinking water should be based on
    clean ground water no advanced treatment.
  • Protection against ground water pollution.
  • Water abstraction should be balanced against
    nature and surface water objectives.

8
Action plans for groundwater protection
  • State authorities carry out a detailed
    hydrogeological investigation of the ground water
    ressources in Denmark.
  • The investigations are financed by tax on
    abstraction permissions
  • From 1999 - 2006 1.054 mill. kr. (140 mill.
    Euro).
  • The results are used by local authorities as the
    foundation of action plans for ground water
    protection.

9
Ground water protection at the wellfields of
Odense Water
  • At present a detailed hydrogeological
    investigation are being carried out by the state
    authority in cooporation with Odense Water
  • The results of the investigation is expected by
    2009 and forth
  • The first groundwater protection plan is expected
    in 2010
  • Meanwhile we are getting prepared for the
    effort……..

10
Groundwater protection strategy of Odense Water
  • Proactive role in ground water protection
  • Basis for cooporation with authorities
  • Framework for our future investments in ground
    water protection
  • The aim is cost-effective investments in ground
    water protection for the benefit of our consumers
    and their descendants

11
Groundwater protection strategy of Odense Water
Headlines
  • General actions (geographically unspecific)
  • coorporation with environmental authorities
  • communicating the need for groundwater protection
  • protection of interests through The Danish Water
    and Wastewater Association
  • education
  • etc.
  • Specific actions (geographically specific)
  • based on an detailed hydrological investigation
  • detailed zonation of catchments (areas of
    interest)
  • program of measures

!
12
Premises for specific actions
  • Centralized wellfields - considerable ground
    water abstraction help to ensure
    cost-effectiveness in ground water protection.
  • Sustainable ground water abstraction - minimizes
    deterioration of the ground water quality due to
    exploitation. Consideration of vulnerable nature.
  • Optimized abstraction strategy - minimizes human
    and natural threats towards groundwater quality
    on the wellfields.
  • Up to date waterworks - high technical standard
    minimizes the risks of polluting the drinking
    water from source to consumer.

13
(No Transcript)
14
Subdevision of the catchments Focus
  • Ground water recharge
  • Ground water vulnerability (nitrate)
  • Travel time (based on numerical modelling and
    particle tracking)

15
Subdivision of the catchments Terminology
16
Travel time
  • Negative correlation between transportation time
    and risk of contamination.
  • Transportation time separates the near from the
    distant catchment.
  • Near catchment Zone 1-3
  • Distant catchment Zone 4-6
  • Why use travel time in the aquifer instead of
    total travel time?
  • Why 25 years?


Life expectancy map
17
Why 25 years?
  • Inspired by Dutch and Canadian practice.
  • Exclusion of particles trapped in aquitards and
    inclusion of the hydrologically active parts of
    the saturated zone.
  • General assumptions and experiences with
    degradation, dispersion, diffusion and dilution
    of organic hazardous substances in groundwater.
  • But………it is a rather pragmatic solution that
    works quite well in the hydrogeological setting
    of Denmark.
  • It is certainly a big step in the right direction
    towards cost-effective investments in groundwater
    protection, but it is not rocket science.

18
Wellhead protection zones (BNBO)
  • BNBO1 Travel time less than 1 year.
  • BNBO2 Travel time between 1 and 2 years.
  • Differentiation of groundwater protection near
    abstraction wells.
  • Why?
  • Not all threats in the proximity of the
    wellfields are equal.

19
Wellhead protection zones (BNBO)
1 year
2 years
25 years
20
Conclusions
  • The measures are well known and well tested in
    Denmark. But the combination of measures and
    areas of interest calls for attention.
  • A detailed subdivision of the catchments based on
    knowledge about groundwater recharge, aquifer
    vulnerability and travel time.
  • The use of travel time through introduction of
    differentiated wellhead protection and the 25
    year boundary distinguish the strategy from
    common practice in Denmark.
  • The use of travel time in the groundwater
    protection strategy gives more attention to the
    threats towards the wellfields.

21
Perspectives
  • Well Vulnerability A Quantitative Approach for
    Source Water Protection, Ground Water, vol. 44,
    nr. 5, p. 732 742 by Frind, E.O., Molson, J.W.
    and Rudolph, D.L.
  • Integration of travel time in the vulnerability
    assessment.
  • Aquifer vulnerability 3D groundwater
    protection.
  • Well vulnerability 4D groundwater protection.
  • This knowledge is of great importance when……..
  • prioritizing the groundwater protecting actions
    in a cost-effective manner.
  • planning hydrogeological surveys.

22
  • It is time the thoughts behind the concept well
    vulnerability gains more attention in Denmark
    like the well established concept aquifer
    vulnerability.
  • Because……..at the end of the day a drinking water
    producer shall be more concerned about the
    consumers than the aquifers.

23
Thank you for your attention!
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