Contaminated soil - mycourses.aalto.fi · • Supplies ca. 65% of drinking water • 60% of cities...
Transcript of Contaminated soil - mycourses.aalto.fi · • Supplies ca. 65% of drinking water • 60% of cities...
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Contaminated soil
– focus on groundwater pollution
Jaana Sorvari
Contaminated soil: how you define it ?
Very generally:
Soil that has harmful chemicals in it
Regulatory perspective:
e.g. UK: Causes significant
• harm to people or protected species
• pollution of surface waters or groundwater
In Finland also:
• can cause impairment of site’s amenity
• can otherwise violate the private or public
interest”
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→ determined by hazards or RISKS, NOT directly by concentrations
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Diffuse & point sources
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Point sources, Europe
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About groundwater
Facts, global scale
• GW represents over 90% of
world’s readily available
freshwater
• Drinking water source for ca.
1,5 bil. people
• Ca. 600-700 km3 extracted /
year ≈ 20% of global water
withdrawals
Groundwater areas in Europe
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Facts & threats, Europe
• Supplies ca. 65% of drinking water
• 60% of cities overexploit their resources
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Finnish perspective
Almost 24 000 registered,
potentially contaminated sites
• 4 350 (18 %) is in classified GW areas
• Of the 4 350, > 83 % is in I class GW area
• > 500 sites < 100 m from a classifiedGW area
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Case: The story of Kärkölä, Finland
How everything started…the source
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A sawmill area of Koskisen Ltd.
• in operation since 1931
Chemicals
• from 1940’s till 1984 wood
preservation using KY5 chemical
Environment
• groundwater area class I, nearest
waterworks serves 3500 inhabitants
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What is KY5 ?
Effective ingredients
• chlorinated phenols (CP)
• also polychlorinated dioxins (PCDD) and
furans (PCDF) as impurities
CPs
• easily soluble in water
• highly toxic to aquatic organisms
• manifestations in humans: in liver, kidneys,
skin, gastric system, immune system; cancer
• can transform to more toxic compounds (e.g.
PCDDs+PCDFs)
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What happened ?
A fire in May 1976
→ Sawmill plant and chemical
storage partly destroyed
→ → KY5 with CPs emitted to
the environment, exact volume
unknown*
Also (?): careless handling of
KY5 overflow of KY5 pool
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Migration to groundwater*3300 kg according to later estimates
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Consequences
Groundwater
• in 1987: CP in waterworks > 10 x quality standard for standard for household water (10 ug/l)
→ waterworks closed 12/1987
• later: outside waterworks CP 56 000-190 000 µg/l
Edible fish, lake Valkjärvi
• CP in fish > 7000* µg/kg (max, much higher in liver)
Humans
• elevated concentrations of CP in urea, particularly persons eating fishfrom adjoining lake Valkjärvi
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*EU’s generic default limit value (MRL) for PCP in food 10 µg/kg
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Different stakeholders, different reactions
Municipal manager:
”breathing the air in Helsinki or passive smoking is more risky
than eating the fish from Valkjärvi”
”health risks from eating the fish from Valkjärvi are insignificant”
”media has excaggerated the health risks”
Minister of the Environment:
”worst case ever”
Residents:
”information has been concealed”
CEO of Koskisen Oy
”minister should resign”
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Signs in human beings
• Several symptoms, e.g.
gastrointestinal and dermal
manifestations, respiratory
infections; dose-response
correlation confirmed
• Cancers in 1972-1986:
excess of soft-tissue sarcomas
and non-Hodgkin’s lymphomas
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Scene 1: The long arm of the law gets a grasp ?
The CEO charged for polluting the groundwater and
claims presented to the court…
BUT
the Water Rights Court dismissed the claims since:
”no connection between the contamination of water in
the water plant and working methods used in the
sawmill has been demonstrated”
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Next step - the Water Rights Appeal Court…
…keeps the previous decision but states (05/1993) that
• based on the studies on lake sediments, CPs have entered to soiland GW also before the fire
• there are no other probable sources of CPs
• the defendant was responsible for preventing GW contamination
HOWEVER
• ”No such information was available by the time of the use of KY5 that would let one to assume that when present in soil it poses a risk to groundwater; particularly when alsoconsidering soil type (clay) and direction of surface water flow”
= no indifference shown in handling KY5 and
= it was not predictable that handling KY5 could contaminate
GW in waterworks (distance 800 m)
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The media is interested…
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…and so are researchers
Studies on
• population health
• contamination of lake Valkjärvi
• geological conditions
• transport of CPs in groundwater
(modeling)
• GW remediation methods
• …
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And the lawyers profit…
Various appeals, statements, decisions,
and an administrative compulsion
Various issues
• Time of the accident (fire) vs. date when the
Waste Management Law came into force
(01/04/1979)
• Regional authority’s decision on the
environmental permit application
• Non-intention: many studies imply that high CP
concentrations not related to the normal activities
and use of KY5
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Closing the case
Supreme Administrative Court’s decision
10/2008
• Koskisen Ltd is responsible for groundwatercontamination
• No remediation targets defined, however
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Remediation attempts
Ex situ: Treatment in municipal waste water
plant (activated sludge) 1989-1992
• ca. 50 kg CP removed
• would take ca. 90 years
On site: Pump & treat
activated carbon 12/1993-1997
• ca. 360 kg CP removed
• too expensive
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Remediationattempts
On site: Pump & treat
bioreactor 1/1995-1999
- Based on bacteria
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Results from the bioreactor treatment
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CP concentration µg/l
CP reduction
87 – 98 %, ca.
760 kg CP
removed
In 1999
operation
disturbed
Only 10-15%
of GW formed
daily cleaned
Input
Output
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Final solution – ”underground bioreactor”Remediation plan accepted 02/2012
New in situ remediation started 25/06/2012
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Absorption
well Abstraction
well
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Results from the in situ ”bioreactor”
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CP reduction 91 - 92 %
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Months from the start
To
tal c
on
ce
ntr
ati
on
µg
/l
Recharge GW
CP concentration
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Future of Kärkölä groundwater
Good status (as defined in the
legislation) can most probably be
attained by 2027
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Concluding remarks
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Your lessons learned ?
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Challenges to ground water riskassessment and remediation
• Hydrogeological conditions
• Soil heterogeneity: prediction of contaminant transport
from unsaturated zone to saturated zone
• Transport in fractured bedrock
• Degradation (organic pollutants): effect of environmental
conditions
• Non-aqueous phase liquids (NAPL)
• Multiple contaminants
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