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Mine Pool Mapping The Pittsburgh Seam. Bruce Leavitt, P.E., P.G. Consulting Hydrogeologist. Acknowledgements. Joe Donovan, Ph.D. Eberhard Werner Brenden Duffy Hydrology Research Center WV Water Research Institute West Virginia University. Pittsburgh Coal Basin. - PowerPoint PPT Presentation
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Mine Pool Mapping Mine Pool Mapping The Pittsburgh SeamThe Pittsburgh Seam
Bruce Leavitt, P.E., P.G.Consulting Hydrogeologist
AcknowledgementsAcknowledgements
Joe Donovan, Ph.D.
Eberhard Werner
Brenden Duffy
Hydrology Research CenterWV Water Research Institute
West Virginia University
PittsburghPittsburghCoal Coal BasinBasin
Mine water in the Mine water in the Pittsburgh coal basinPittsburgh coal basin
largest and oldest bituminous coal basin in North America
currently about 55% of reserves are mined out between 1980 and today, a large number of mine closures
have occurred in mines extending to outcrop flooding of these nearly closed mines has created a new
set of groundwater conditions and environmental threats the few deep mines (11) still active are deeper in the
basin and hydraulically isolated from this mine-flooding risk
pH Monongahela River
2
3
4
5
6
7
8
1-Jan-57 1-Jan-61 1-Jan-65 1-Jan-69 1-Jan-73 1-Jan-77
Three Hydrologic SettingsThree Hydrologic Settings
Flooded High Dilution
River
overburden
Mine Discharge
Flooded Mine Low Dilution
River
overburden
MinePump
No Discharge
Unflooded, Free Draining
River
overburden Mine Discharge
major categories of mine floodingmajor categories of mine flooding
free draining: above drainage mines -- many currently-discharging
active: pumped dry flooding: water level rising; mine resaturating fully-flooded
– with control: water level stabilized by pumping and/or barrier leakage– without control surface discharge occurs
Mining FactsMining Facts
4,991 square miles mined 1,941 square miles flooded 1.36 trillion gallons in storage 27.19 billion gallons discharged per year 63.4 % does not go through a treatment plant 37.8 % of the acidity is untreated 40 % of the iron is untreated 97.7 % of the aluminum is untreated
Geochemistry in flooded minesGeochemistry in flooded mines
Effect of Flooding on Mine Effect of Flooding on Mine Water ChemistryWater Chemistry
Rapid dissolution of acidic saltsExclusion of oxygen from the mineChemical reaction with recharging
ground water.
Montour MineMontour Mine
14,000 AcresMaximum overburden 850 feetClosed in 198056 % floodedFlooded to 125 feet from surfacePumped at 3,500 gallons per minuteResidence time 5 to 6 years
Montour 4 Water Levels and Pumping Rates
650
700
750
800
850
Jan-80 Jan-84 Jan-88 Jan-92 Jan-96
wat
er le
vel e
leva
tion
(ft)
0
100
200
300
400
pum
ping
rat
e (L
/s)
Hahn shaft WL
Southwest shaft WL
McMurray shaft WL
Hahn pumping rate
0
500
1000
1500
0 2 4 6 8 10 12 14 16
years after flooding
Fe, C
a, M
g (m
g/L)
0
1000
2000
3000
4000
5000
Na (m
g/L)
Fe
Ca
Mg
Na
Post-flooding chemistry of water pumped from the Montour mine
-500
0
500
1000
1500
2000
2500
0 2 4 6 8 10 12 14 16
years after flooding
acid
ity (m
g/L
as C
aCO
3)
2
4
6
8
pH
alkalinity
net acidity
pH
Post-flooding chemistry of alkalinity, calculated acidity, and pH in water pumped from the Montour mine
0
10
20
30
40
0 2 4 6 8 10 12 14 16
years after flooding
Al, M
n (m
g/L)
2
4
6
8
pHAl
Mn
pH
Post-flooding chemistry of Al and Mn in water pumped from the Montour mine
Geochemistry of Free Draining Geochemistry of Free Draining MinesMines
Maiden #1 MineMaiden #1 MineDunkard CreekDunkard Creek
pH 3.1Acidity 219 mg/lIron 25 mg/lAluminum 23 mg/l
current metals current metals fluxes,fluxes,flooded mine flooded mine dischargesdischargesyear 2002 year 2002
green=iron
yellow=aluminum
manganese=purple#
#
#
#
#
#
E
E
EEEE
EEEEEE
E
EE
E
E
E EEE
E
EE
E
E EE EEEE
E
E
E
EEEEE
EE
E
E EEE E EE EEE E EEE
EEE
EE
E
EE
E
EEE
E
E
E
EE
E
E
E
EE
E
E
E
E
E
E
E
EE
EEE
EE
EE
EEEEEEEEEE
EEE
E
E
EEE
$Z
$Z
$Z
$Z$Z
$Z
$Z
$Z
$Z$Z
$Z
$Z
$Z
$Z
$Z
$Z
$Z
$Z
$Z $Z $Z$Z
active miningknown / inferred flooding
Iron tons/yrAluminum tons/yrManganese tons/yr
$Z treatment plant
extent of mining
u discharge
Legend
Hydrology Research Center
5 0 5 10 15 20 25 Miles
PennsylvaniaWest Virginia
Ohio
Washington
Pittsburgh
Morgantown
Fairmont
Clarksburg
Chemload2.shp
Wheeling
Distribution of metals loadin the Pittsburgh coal basin
N
EW
S
Metalsload.shpMetalsload.shpMetalsload.shp
1750 T Scale (circle radius)
Preliminary Draft
MineMinedischargesdischargesthat duethat duenot requirenot requiretreatment.treatment. Gates
Palmer
Adah
Canonsburg
ConclusionsConclusions
Water discharging from Pittsburgh seam underground mines are of two distinct types.
Flooded mines ultimately produce net alkaline water with low metals concentrations. Eventually these mines may be suitable for discharge without treatment.
Free draining mines generate low pH, aluminum dominated discharges that are expected to persist for decades.
Conclusions Conclusions continuedcontinued
Underground mining in the Pittsburgh seam has created the most prolific aquifer in Western half of the State.
Utilization of this aquifer is in its infancy. More than 27 billion gallons available per year. 1.36 trillion gallons available in storage. Mapping of the extent of mine flooding can
promote mine water utilization, and watershed restoration.
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