geochemical and hydrologic controls on abandoned coal mine discharge
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Geochemical and Hydrologic Controls on Mine Drainage: Anthracite Coal Fields, PA, 1975-2012
J.E. Burrows1, S.C. Peters1, and C.A. Cravotta, III2
1 Department of Earth and Environmental Sciences, Lehigh University, Bethlehem, PA 18015
2 USGS, U.S. Geological Survey, Pennsylvania Water Science Center, New Cumberland, PA 17070
Exposure to oxygen and moisture produces Fe2+, SO4, and acid:
FeS2 + 14Fe3+ + 8H2O 15Fe2+ +2SO42- +16H+ (1)
Fe+3 Ferric Iron
Fe+2 Ferrous Iron
AerobicHigh pH
AnaerobicLow pH
Exposure to oxygen and moisture produces Fe2+, SO4, and acid:
FeS2 + 14Fe3+ + 8H2O 15Fe2+ +2SO42- +16H+ (1)
Fe2+ is transformed through the following reactions:
Fe2+ + 0.25O2 + H+ Fe3+ + 0.5H2O (2)
Fe3+ + 3H2O Fe(OH)3 + 3H+ (3)
Fe2+ + 0.25O2 + 2.5 H2O Fe(OH)3 + 2H+ (4)
pH
Site 2
Site 3
Higher pH results in the precipitation
of Fe
Lee et al, 2002, Appl. Geochem.
Site 1
Wood et al., 1999, Quat. Jour. Eng. Geo.
Wood et al., 1999, Quat. Jour. Eng. Geo.
Scranton
Wilkes-Barre
Bethlehem
● Sampling Sites■ Coal Mining Operations Cities
Scranton
Wilkes-Barre
Bethlehem
● Sampling Sites■ Coal Mining Operations Cities
1975 1991 1999 2012
Growitz et al., 1985, USGS Report
Wood, 1991, USGS Report
Cravotta, 2008, Appl. Geochem.
This Study
2/9/99 7/9/99 12/6/99 5/4/00 10/1/002.5
3.5
4.5
5.5
6.5
7.5
pHAskam shaft
Sampling Date (M/D/Y)
pH
2.5
3.5
4.5
5.5
6.5
7.5
pHHoney pot Outfall
pH
020406080
100120140160180 Fe
Honeypot outfall
Fe
(m
g/L
)
2.5
3.5
4.5
5.5
6.5
7.5
pHValley View
pH
020406080
100120140160180 Fe
Valley View
Fe
(m
g/L
)
2/9/99 7/9/99 12/6/99 5/4/00 10/1/000
20406080
100120140160180 Fe
Askam shaft
Sampling Date (M/D/Y)
Fe
(m
g/L
)
1975 1985 1995 20050
10
20
30
40
50
60
Sampling Year
Fe
(m
g/L
)
1975 1985 1995 20050
100
200
300
400
500
600
700
Sampling Year
SO
4 (
mg
/L)
pH SO4Fe
Median
Std Deviation Std Deviation
Median
Std Deviation
Median
pH SO4Fe
A) B) C)
D) E) F)
MeanMean
Mean
0
500
1000
1500
2000
2500
3000
SO
4 (
mg
/L)
1975 1985 1995 20050
1
2
3
4
5
6
7
Sampling Year
pH
0
20
40
60
80
100
120
140
160
180
200
Fe
(m
g/L
)
2.5
3.5
4.5
5.5
6.5
7.5
pH
1975 1985 1995 20050
10
20
30
40
50
60
Sampling Year
Fe
(m
g/L
)
1975 1985 1995 20050
100
200
300
400
500
600
700
Sampling Year
SO
4 (
mg
/L)
pH SO4Fe
Median
Std Deviation Std Deviation
Median
Std Deviation
Median
pH SO4Fe
A) B) C)
D) E) F)
MeanMean
Mean
0
500
1000
1500
2000
2500
3000
SO
4 (
mg
/L)
1975 1985 1995 20050
1
2
3
4
5
6
7
Sampling Year
pH
0
20
40
60
80
100
120
140
160
180
200
Fe
(m
g/L
)
2.5
3.5
4.5
5.5
6.5
7.5
pH
1975 1985 1995 20050
10
20
30
40
50
60
Sampling Year
Fe
(m
g/L
)
1975 1985 1995 20050
100
200
300
400
500
600
700
Sampling Year
SO
4 (
mg
/L)
pH SO4Fe
Median
Std Deviation Std Deviation
Median
Std Deviation
Median
pH SO4Fe
A) B) C)
D) E) F)
MeanMean
Mean
0
500
1000
1500
2000
2500
3000
SO
4 (
mg
/L)
1975 1985 1995 20050
1
2
3
4
5
6
7
Sampling Year
pH
0
20
40
60
80
100
120
140
160
180
200
Fe
(m
g/L
)
2.5
3.5
4.5
5.5
6.5
7.5
pH
1975 1985 1995 20050
10
20
30
40
50
60
Sampling Year
Fe
(m
g/L
)
1975 1985 1995 20050
100
200
300
400
500
600
700
Sampling Year
SO
4 (
mg
/L)
pH SO4Fe
Median
Std Deviation Std Deviation
Median
Std Deviation
Median
pH SO4Fe
A) B) C)
D) E) F)
MeanMean
Mean
0
500
1000
1500
2000
2500
3000
SO
4 (
mg
/L)
1975 1985 1995 20050
1
2
3
4
5
6
7
Sampling Year
pH
0
20
40
60
80
100
120
140
160
180
200
Fe
(m
g/L
)
2.5
3.5
4.5
5.5
6.5
7.5
pH
Time Interval
Parameter ’75-‘91 ’91-‘99 ’99-‘12 ’75-‘12
Fe (mg/L) 0.080 0.005 0.081 0.165
SO4 (mg/L) 0.600 <0.001 0.091 0.002
pH <0.001 <0.001 0.046 0.008
Non-parametric Matched Pairs Significance Level p<0.05
1975 1985 1995 20050
10
20
30
40
50
60
Sampling Year
Fe
(m
g/L
)
1975 1985 1995 20050
100
200
300
400
500
600
700
Sampling Year
SO
4 (
mg
/L)
pH SO4Fe
Median
Std Deviation Std Deviation
Median
Std Deviation
Median
pH SO4Fe
A) B) C)
D) E) F)
MeanMean
Mean
0
500
1000
1500
2000
2500
3000
SO
4 (
mg
/L)
1975 1985 1995 20050
1
2
3
4
5
6
7
Sampling Year
pH
0
20
40
60
80
100
120
140
160
180
200
Fe
(m
g/L
)
2.5
3.5
4.5
5.5
6.5
7.5
pH
EPCAMR John Welsh
Flux = Concentration x Discharge
1975 1985 1995 20050
0.005
0.01
0.015
0.02
0.025
0.03
0.035
Sampling Year
Fe
flu
x (
mg
/s)
1975 1985 1995 20050
0.1
0.2
0.3
0.4
0.5
0.6
0.7
Sampling Year
Dis
ch
arg
e (
m3
/s)
1975 1985 1995 20050
0.1
0.2
0.3
0.4
0.5
0.6
0.7
Sampling Year
SO
4 F
lux
(m
g/s
)Median
Std Deviation
MedianMedian
Std DeviationStd Deviation
Fe Flux
Fe Flux SO4 Flux
SO4 FluxDischarge
Discharge
A) B) C)
D) E) F)
MeanMean
Mean
0
0.5
1
1.5
2
2.5
3D
isc
ha
rge
(m
3/s
)
0
0.5
1
1.5
2
2.5
SO
4 F
lux
(m
g/s
)
0
0.05
0.1
0.15
0.2
0.25
Fe
Flu
x (
mg
/s)
Demchak et al., 2004, Jour. Env. Qual.
Above: exposed rock surfaces facilitate O2 transport and continual pyrite dissolution, alkalinity consumption
Demchak et al., 2004, Jour. Env. Qual.
Demchak et al., 2004, Jour. Env. Qual.
Above: exposed rock surfaces facilitate O2 transport and continual pyrite dissolution, alkalinity consumption
Below: groundwater inputs with low dissolved O2, resulting in a decrease of pyrite oxidation
0
20
40
60
80
100
120
140
160
180
200
Fe
(m
g/)
pH SO4Fe
A) B) C)
2.5
3.5
4.5
5.5
6.5
7.5
pH
1975 1985 1995 20050.5
1.5
2.5
3.5
4.5
5.5
6.5
Sampling Year
pH
Mean
Std Dev
1975 1985 1995 20057
12
17
22
27
32
37
42
47
52
Sampling Year
Fe
(m
g/L
)
Mean
Std Dev
Mean
1975 1985 1995 20050
100
200
300
400
500
600
700
800
Sampling Year
SO
4(m
g/L
)
0
500
1000
1500
2000
2500
3000
SO
4 (
mg
/L)
Mean
Mean
Std Dev
Above: blackBelow: gray
Sampling YearDrainage
Type‘75-’91 ‘91-’99 ‘99-’12 ‘75-’12
Above
pH 0.075 0.106 0.204 0.108
Fe 0.867 0.089 0.402 0.799
SO4 0.611 0.050 0.866 0.402
Below
pH 0.003 0.004 0.099 0.043
Fe 0.045 0.007 0.091 0.028
SO4 0.289 0.009 0.084 0.004
Non-parametric Matched Pairs Significance Level p<0.05
Sampling YearDrainage
Type‘75-’91 ‘91-’99 ‘99-’12 ‘75-’12
Above
pH 0.075 0.106 0.204 0.108
Fe 0.867 0.089 0.402 0.799
SO4 0.611 0.050 0.866 0.402
Below
pH 0.003 0.004 0.099 0.043
Fe 0.045 0.007 0.091 0.028
SO4 0.289 0.009 0.084 0.004
Non-parametric Matched Pairs Significance Level p<0.05
0
20
40
60
80
100
120
140
160
180
200
Fe
(m
g/)
pH SO4Fe
A) B) C)
2.5
3.5
4.5
5.5
6.5
7.5
pH
1975 1985 1995 20050.5
1.5
2.5
3.5
4.5
5.5
6.5
Sampling Year
pH
Mean
Std Dev
1975 1985 1995 20057
12
17
22
27
32
37
42
47
52
Sampling Year
Fe
(m
g/L
)
Mean
Std Dev
Mean
1975 1985 1995 20050
100
200
300
400
500
600
700
800
Sampling Year
SO
4(m
g/L
)
0
500
1000
1500
2000
2500
3000
SO
4 (
mg
/L)
Mean
Mean
Std Dev
Above: blackBelow: gray
Exposure to oxygen and moisture produces Fe2+, SO4, and acid:
FeS2 + 14Fe3+ + 8H2O 15Fe2+ +2SO42- +16H+ (1)
Fe2+ is transformed through the following reactions:
Fe2+ + 0.25O2 + H+ Fe3+ + 0.5H2O (2)
Fe3+ + 3H2O Fe(OH)3 + 3H+ (3)
Fe2+ + 0.25O2 + 2.5 H2O Fe(OH)3 + 2H+ (4)
0 20 40 60 80 100 1200
0.05
0.1
0.15
0.2
0.25
Dissolved Oxygen (% Saturation)
Re
lati
ve
fre
qu
en
cy
0 20 40 60 80 100 1200
0.05
0.1
0.15
0.2
0.25
Dissolved Oxygen (% Saturation)R
ela
tiv
e f
req
ue
nc
y
Below-Drainage Above-Drainage
Below-Drainage Above-Drainage
0 20 40 60 80 100 120 1400
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
Alkalinity (mg/L CaCO3)
Re
lati
ve
fre
qu
en
cy
0 20 40 60 80 100 120 1400
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
Alkalinity (mg/L CaCO3)
Re
lati
ve
fre
qu
en
cy
0
20
40
60
80
100
120
140
160
180
200
Fe
(m
g/)
pH SO4Fe
A) B) C)
Above: blackBelow: gray
2.5
3.5
4.5
5.5
6.5
7.5
pH
1975 1985 1995 20050.5
1.5
2.5
3.5
4.5
5.5
6.5
Sampling Year
pH
Mean
Std Dev
1975 1985 1995 20057
12
17
22
27
32
37
42
47
52
Sampling Year
Fe
(m
g/L
)
Mean
Std Dev
Mean
1975 1985 1995 20050
100
200
300
400
500
600
700
800
Sampling Year
SO
4(m
g/L
)
0
500
1000
1500
2000
2500
3000
SO
4 (
mg
/L)
Mean
Mean
Std Dev
0 1 2 3 4 5 6 7 80
0.5
1
1.5
2
2.5
3
3.5
4
S (moles)
Fe
(m
ole
s)
Pyrite (2:1)
Samples (2.3:1)
Molar Ratio S:Fe
2 3 4 5 6 7 8 9 100
2
4
6
8
10
12
14
16
pH
-Lo
g A
cti
vit
y
2 3 4 5 6 7 8 9 100
2
4
6
8
10
12
14
16
Fe tot 1999
Fe(III)1999
Fe tot 2012
Fe(III)2012
pH
-Lo
g A
cti
vit
y
2 3 4 5 6 7 8 9 100
2
4
6
8
10
12
14
16
Fe tot 1999
Fe(III)1999
Fe tot 2012
Fe(III)2012
pH
-Lo
g A
cti
vit
y
Goethite
Jarosite
Schwertmannite
Ferrihydrite
2 3 4 5 6 7 8 9 100
1
2
3
4
5
6
7
8
pH
-Lo
g A
cti
vit
y F
e (
III)
Jarosite
Schwertmannite
Ferrihydrite
2 3 4 5 6 7 8 9 100
1
2
3
4
5
6
7
8
Fe tot 1999
Fe(III)1999
Fe tot 2012
Fe(III)2012
pH
-Lo
g A
cti
vit
y
Jarosite
Schwertmannite
Ferrihydrite
1 -
.5 -
0 -
-.5 -Troilite
FerrihydriteJarosite
Schwertmannite
FeSO4 (aq)
Pyrite
Fe++
Fe3+
Fe(OH)++Fe(OH)2
+
FeOH+
FeOFe++
2 3 4 5 6 7 8 9 10 pH
I I I I I I I
Eh
(V)
Conclusions
• Differences in pH, Fe, and SO4 were significant (p<0.05) for below-drainage mines
• Above-drainage discharges did not see any significant changes
• Fe(II) is the dominant Fe species, and transformation to Fe(III) may be limited by O2 transport.
• Saturation of Fe(III) precipitates varies with pH and Fe and SO4 concentrations: increasing pH and decreasing concentrations of Fe and SO4 limit the precipitation of K-jarosite and schwertmannite and favor precipitation of Fe(III) oxides.
Thank you!
• EPCAMR• Earth Conservancy• PA DEP• PA GIS and Tax
Assessors Offices• LU Environmental
Initiative
• LU EES Department• Kayla Virgone• Joe Solly• Kate Semmens• Paul Henry• George Yasko
References• Pine Knot Tunnel Discharge image http://www.undergroundminers.com/oakhill.html
• Cravotta, C.A., III, 2008a, Dissolved metals and associated constituents in abandoned coal-mine discharges, Pennsylvania, USA. Part 1: Constituent quantities and correlations, Appl. Geochem., 23, 166-202.
• Cravotta, C.A., III, 2008b, Dissolved metals and associated constituents in abandoned coal-mine discharges, Pennsylvania, USA. Part 2: Geochemical controls on constituent concentration, Appl. Geochem, 23, 203-226.
• Lee, G., Bigham, J.M., Faure, G., 2002, Removal of trace metals by coprecipitation with Fe, Al, and Mn from natural waters contaminated with acid mine drainage in the Ducktown Mining District, Tennessee: Appl. Geochem., 17, 569-581.
• Growitz, D.J., Reed, L.A., Bear, M.M., 1985, Reconnaissance of mine drainage in the coal fields of Eastern Pennsylvania, U.S. Geological Society Water-Resources Investigations Report, 83-4274.
• Wood, C.R., 1991, Water quality of the large discharges from mines in the anthracite region of Eastern Pennsylvania, U.S. Geological Society Water-Resources Investigations Report, 95-4243.
• Wood, S.C., Younger, P.L., Robins, N.S., 1999, Long-term changes in the quality of polluted minewater discharges from abandoned underground coal workings in Scotland, Quat. J. of Eng. Geo., 32, 69-79.
Discharges Sampled
• Coalbrook Mine (lower Wilson Creek Shaft)
• Gravity Slope (Peckville Shaft)• Old Forge Borehole• Duryea Breech Seep• Butler Mine tunnel (Pittston
Water Level Tunnel)• South Wilkes-Barre Boreholes • Buttonwood Outfall• Beaver Meadow Outfall• Oneida Tunnel• Scott Ridge Mine Tunnel• Cameron Mine Airshaft• Cameron Mine Drift
• Silverbrook Mine• Colket Mine• Tracy Airhole• Rowe Tunnel Discharge• Valley View Tunnel• Jermyn Mine• Honeypot Outfall• Maysville Mine Borehole at
Ranshaw• Henry Clay Stirling Mine Pump• Big Mtn Mine no. 1 Slope• Markson Columnway• Porter Tunnel near Tower City
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