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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
2
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
5
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
8
Monitoring wells
9
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.
10
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)
13
Finite element mesh and boundary conditions
14
20-fold oversized longitudinal section - 2D or 3D?
Monte Scherbelino
404 428418
404428
418
15
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)
17
Location of the wells presenting the calibration
18
Results of the transient model calibration
19
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
]
21
Location of the observed wells
22
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
23
Transient transport modelling for chloride, wells M1 and 420
SPRINGAuswertung SITRA DURCHBRUCHSKURVE KNOTEN-NR.: 3 BEZUGSDATUM T=0 : 1.10.1968
ZEIT IN TAGEN
Konzentrationen
SPRINGAuswertung SITRA DURCHBRUCHSKURVE KNOTEN-NR.: 30 BEZUGSDATUM T=0 : 1.10.1968
ZEIT IN TAGEN
Konzentrationen
24
Transport modelling chloride:comparison transient and steady-state simulation, well 407
SPRINGAuswertung SITRA DURCHBRUCHSKURVE KNOTEN-NR.: 17 BEZUGSDATUM T=0 : 1.10.1968
ZEIT IN TAGEN
Konzentrationen *101
SPRINGAuswertung SITRA DURCHBRUCHSKURVE KNOTEN-NR.: 17 BEZUGSDATUM T=0 : 1.10.1968
ZEIT IN TAGEN
Konz
entr
atio
nen *1
01
25
Transport modelling chloride:comparison transient and steady-state simulation, well 420
SPRINGAuswertung SITRA DURCHBRUCHSKURVE KNOTEN-NR.: 30 BEZUGSDATUM T=0 : 1.10.1968
ZEIT IN TAGEN
Konzentrationen
SPRINGAuswertung SITRA DURCHBRUCHSKURVE KNOTEN-NR.: 30 BEZUGSDATUM T=0 : 1.10.1968
ZEIT IN TAGEN
Konzentrationen
26
Conservativ transient transport modelling for the COD
SPRINGAuswertung SITRA DURCHBRUCHSKURVE KNOTEN-NR.:18 BEZUGSDATUM T=0 : 1.10.1968
ZEIT IN TAGEN
Konzentrationen *101
SPRINGAuswertung SITRA DURCHBRUCHSKURVE KNOTEN-NR.:3 BEZUGSDATUM T=0 : 1.10.1968
ZEIT IN TAGEN
Konzentrationen
SPRINGAuswertung SITRA DURCHBRUCHSKURVE KNOTEN-NR.:20 BEZUGSDATUM T=0 : 1.10.1968
ZEIT IN TAGEN
Konzentrationen
SPRINGAuswertung SITRA DURCHBRUCHSKURVE KNOTEN-NR.:8538 BEZUGSDATUM T=0 : 1.10.1968
ZEIT IN TAGEN
Konzentrationen *101
27
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.
28
Thanks to the BMBF for supporting the presented work within the funding priority KORA.
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