analysis of the effects of variable recharge on the ... · 1 analysis of the effects of variable...

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Analysis of the effects of variable recharge on the processes of natural attenuation by a longterm

transient simulation

A. Spinola, H. Gerdes, M. Kämpf

Brandt·Gerdes·Sitzmann Umweltplanung GmbH

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What‘s the purpose to model Natural Attenuation in a large scale FE-Model?

To define flow velocities.

To define flowpaths.

To quantify dilution.

-> To define the hydraulic boundary conditions forhydrochemical models.

3

Aerial photograph of the „Monte Scherbelino“ with slurry wall

Slurry wall

100 200 300 400 5000[m]

N

4

History

1925-1968 Filling period with household andindustrial waste and demolition debris

1968-1992 Recultivation and use as recreational area

1984 Demand to clean up the site

9/1994 - 4/1995 Construction of the slurry wall

2003 Remediation of the remaining plume bypump and treat

Construction of a surface sealing

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Adventure playground „Monte Scherbelino“

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History

1925-1968 Filling period with household andindustrial waste and demolition debris

1968-1992 Recultivation and use as recreational area

1984 Demand to clean up the site

9/1994 - 4/1995 Construction of the slurry wall

2003 Remediation of the remaining plume bypump and treat

Construction of a surface sealing

7

Present view of the Monte Scherbelino

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Monitoring wells

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The contamination of the MonteScherbelino is a typical landfill leachate:

• High salt loads (max. EC = 40.000 µS/cm),

• large amounts of organic substances, (max. COD = 4000 mg/l),

• critical heavy metals: Ni, Cr and As,

• beyond the concentration limits: AOX and benzene.

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Monitoring wells 406 and 414

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BTCs for chloride, COD and sulfate at monitoring well 406

1967

1967

1970

19701975

1980

19801985

1990

19901995

2000

2000

Werte vom 1.1.1967 bis 31.12.2004

100

600

1100

1600

2100

2600

3100

3600

Wer

te in

mg/

l

Chem. O2-Bedarf (Cr) Chlorid (Cl) Sulfat (SO4)

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BTCs for chloride, COD and sulfate at monitoring well 414

1.1968

1.11.41.7 1.10

1969

1.11.41.71.10

1970

1.11.4 1.7 1.10

1971

1.11.4 1.7 1.10

1972

1.11.4 1.7 1.10

1973

1.11.41.7 1.10

1974

1.11.41.7 1.10

1975

1.11.41.7 1.10

1976

1.11.41.71.10

1977

1.11.41.7 1.10

1978

1.11.4 1.7 1.10

1979

1.11.41.7 1.10

1980

1.11.41.7 1.10

1981

1.11.41.7 1.10

1982

1.11.41.7 1.10

1983

1.11.4 1.71.10

1984

1.11.41.7 1.10

1985

1.11.4 1.7 1.10

1986

1.11.4 1.7 1.10

1987

1.11.4 1.7 1.10

1988

1.11.41.7 1.10

1989

1.11.4 1.71.10

1990

1.11.4 1.7 1.10

1991

1.11.4 1.7 1.10

1992

1.11.4 1.7 1.10

Werte vom 1.1.1968 bis 31.12.1992

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

150

160

170

180

190

200

Wer

te in

mg/

l

Chem. O2-Bedarf (Cr) Chlorid (Cl) Sulfat (SO4)

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Finite element mesh and boundary conditions

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20-fold oversized longitudinal section - 2D or 3D?

Monte Scherbelino

404 428418

404428

418

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Results of the multiple depth sampling

SPR 621 - Apr. 04 RKS 417 - Apr. 04

2

4

6

8

Tiefe[m u. GOK]

0.01 0.1 1 100.02 0.05 0.2 0.5 2 5Fe II [mg/l]O2 [mg/l]

1000 100003000800Lf [ S/cm]

-50 0 50 100 150 200 250 300 350Eh [mV]

6 7 8pH

10 15 20 25Temp. [ C]

O2

Fe II LfEh pH

Temp

2

4

6

8

Tiefe[m u. GOK]

0.01 0.1 1 100.02 0.05 0.2 0.5 2 5Fe II [mg/l]O2 [mg/l]

1000 100003000800Lf [µS/cm]

-50 0 50 100 150 200 250 300 350Eh [mV]

6 7 8pH

10 15 20 25Temp. [°C]

Fe IILfO2Eh pHTemp

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Hydraulic conductivities and equipotential lines (steady-state)

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Location of the wells presenting the calibration

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Results of the transient model calibration

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Annual recharge rate 1970 - 1990

-0.200

-0.100

0.000

0.100

0.200

0.300

0.400

1970

1971

1972

1973

1974

1975

1976

1977

1978

1979

1980

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

[m/a

]

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Location of the observed wells

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Transient transport modelling for chloride, wells 405 and 407

SPRING DURCHBRUCHSKURVE KNOTEN-NR.: 8538 BEZUGSDATUM T=0 : 1.10.1968

ZEIT IN TAGEN

Konzen

trat

ione

n *1

01

SPRINGAuswertung SITRA DURCHBRUCHSKURVE KNOTEN-NR.: 17 BEZUGSDATUM T=0 : 1.10.1968

ZEIT IN TAGEN

Konz

entr

atio

nen *1

01

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Transient transport modelling for chloride, wells M1 and 420


ZEIT IN TAGEN

Konzentrationen


ZEIT IN TAGEN

Konzentrationen

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Transport modelling chloride:comparison transient and steady-state simulation, well 407


ZEIT IN TAGEN

Konzentrationen *101


ZEIT IN TAGEN

Konz

entr

atio

nen *1

01

25

Transport modelling chloride:comparison transient and steady-state simulation, well 420


ZEIT IN TAGEN

Konzentrationen


ZEIT IN TAGEN

Konzentrationen

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Conservativ transient transport modelling for the COD

SPRINGAuswertung SITRA DURCHBRUCHSKURVE KNOTEN-NR.:18 BEZUGSDATUM T=0 : 1.10.1968

ZEIT IN TAGEN



ZEIT IN TAGEN

Konzentrationen


ZEIT IN TAGEN

Konzentrationen


ZEIT IN TAGEN


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Summary

Stationarity of the plume is a crucial point when considering a NA strategy for groundwater clean up.Transient flow can produce quasi-steady-state conditions in the migration of a plume which could be mistaken for natural attenuation processes.

The ongoing research project will now focus on the significance of heterogeneties and 3D effects.

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Thanks to the BMBF for supporting the presented work within the funding priority KORA.

analysis of the effects of variable recharge on the ... · 1 analysis of the effects of variable...

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