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Mine Dewatering and Water Management at Barrick Goldstrike Mine in the Carlin Trend, Nevada
Johnny Zhan, Ph.D.
Presented at U.S. EPA Hardrock Mining Conference 2012Denver, CO, USA, April 3-5, 2012
1. Introduction to Barrick and Goldstrike2. Goldstrike Dewatering System3. Goldstrike Monitoring System4. Impact Evaluation5. Conclusions
April 3-5, 2012 U.S. EPA Hardrock Mining Conference 2012
Presentation ContentsPresentation Contents
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Distance:1 meter = 3.3 feet
Flow rate:1 liters/second = 16 gallons/minute (gpm)
Weight (Gold):1 tonne = 32,000 troy ounces
April 3-5, 2012
Unit ConversionUnit Conversion
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1. Introduction – Barrick
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SouthAmerica
Lagunas NortePierina
ZaldívarCerro CasalePascua-Lama Veladero
NorthAmerica
Donlin Creek
GoldenSunlight
HemloGoldstrike
Turquoise RidgeMarigold
Bald MountainCortez
Ruby HillRound Mountain
Pueblo Viejo
ProjectMine
AfricanBarrick
North MaraKabangaTulawaka
BulyanhuluBuzwagi
AustraliaPacificPorgera
CowalGranny Smith
KalgoorlieKanowna
Plutonic DarlotLawlers
Reko DiqJabal Sayid
Lumwana
Barrick Global Operations – Equinox Addition
PlutonicDarlot
KalgoorlieLawlers
CowalKanowna
Granny Smith
Porgera
A U S T R A L I A
P A P U AN E W G U I N E A
Mines Projects
Lumwana
Jabal Sayid
ZAMBIA
SAUDI ARABIA
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April 3-5, 2012 U.S. EPA Hardrock Mining Conference 2012
1. Introduction – Goldstrike Mine1. Introduction – Goldstrike Mine
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April 3-5, 2012 U.S. EPA Hardrock Mining Conference 2012
Open PitOpen Pit
400 m400 m
3,700 m3,700 m
2,000 m2,000 m
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April 3-5, 2012 U.S. EPA Hardrock Mining Conference 2012
Underground MinesUnderground Mines
Pre-mining water table1600 m amsl
Current water table1100 m amsl with a drawdown of 500 m
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April 3-5, 2012 U.S. EPA Hardrock Mining Conference 2012
2. Goldstrike Dewatering System2. Goldstrike Dewatering System
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April 3-5, 2012 U.S. EPA Hardrock Mining Conference 2012
Dewatering System - ActiveDewatering System - Active
Pumping well -Depth: 1000 mDiameter: 50 cmRate: 200 l/s (3,000 gpm)Power: 2,000 HPCost: US$3 Million/Each
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April 3-5, 2012 U.S. EPA Hardrock Mining Conference 2012
Dewatering System - ActiveDewatering System - Active
Piezometer
Local WellRegional Well
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Dewatering System - PassiveDewatering System - Passive
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April 3-5, 2012 U.S. EPA Hardrock Mining Conference 2012
Dewatering System - PassiveDewatering System - Passive
HD (1994 – 2002)• Numbers: 1800
• Length: 10 – 450 m
•Total Length: 380 km
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April 3-5, 2012 U.S. EPA Hardrock Mining Conference 2012
Water Management System Water Management System
560,000 m2/Each
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April 3-5, 2012 U.S. EPA Hardrock Mining Conference 2012
Cumulative Water BalanceCumulative Water Balance
10%
27%
52%
6%
5%
Mine Use Irrigation Infiltration/Injection Discharge to Humboldt River Flood Irrigation and Evap
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April 3-5, 2012 U.S. EPA Hardrock Mining Conference 2012
3. Goldstrike Monitoring System – 15,000 km23. Goldstrike Monitoring System – 15,000 km2
Manual/Automatic Surface Water Monitoring
Manual/Automatic Groundwater Monitoring
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Water Level Change To-DateWater Level Change To-Date
Drawdown
Mounding
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New Tools – Ground DeformationNew Tools – Ground DeformationA New Assessment Tool - Interferometric Synthetic Aperture Radar (InSAR)
Identified Subsidence/Uplift Associated with Mine Dewatering 100km x 100km coverage at 5m pixel resolution
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From Massonnet, 1997
April 3-5, 2012 U.S. EPA Hardrock Mining Conference 2012
Ground Deformation – InSAR ResultsGround Deformation – InSAR Results
Subsidence
Uplift
Subsidence and UpliftJune 1, 1992 – Nov 26, 2000
From Katzenstein, 2008
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Monitoring System – InSAR ResultsMonitoring System – InSAR Results
0
2
4
6
8
10
12
14
16
1992 1994 1996 1998 2000 2002 2004 2006
Def
orm
atio
n R
ate
(cm
/yr)
Time (Calendar Year)
Deformation Rate vs. TimeFrom Katzenstein, 2008
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4. Impact Evaluation – Flow Model4. Impact Evaluation – Flow Model
Pre-Mining Water Level(1990-1991)
MODFLOWModel Grids
From Maurer et al., 1996
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April 3-5, 2012 U.S. EPA Hardrock Mining Conference 2012
Flow Model – Steady State (Pre-mining)Flow Model – Steady State (Pre-mining)
4500
5000
5500
6000
6500
7000
4500 5000 5500 6000 6500 7000
Sim
ulat
ed W
ater
Lev
el (f
t am
sl)
Measured Water Level (ft amsl)
sta tistics of obse rved-simula ted water leve lsnumber of wells 167mean observed head 5,289
root mean square error (ft) 24.9standard deviation of residual error (ft) 25.0bias (mean error in ft) -0.79
calibration ratio 0.0119R-squared 0.9981
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Flow Model – Transient (Pit Area) Flow Model – Transient (Pit Area)
3,500
3,700
3,900
4,100
4,300
4,500
4,700
4,900
5,100
5,300
1/1/1988 1/1/1992 1/1/1996 1/1/2000 1/1/2004 1/1/2008
Wat
er le
vel (
ft am
sl)
Measured Pit Composite
Betze simulated, layer 1
Betze simulated, layer 2
Betze simulated, layer 3
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Flow Model – Transient (Mountain Block) Flow Model – Transient (Mountain Block)
6,000
6,100
6,200
6,300
6,400
6,500
6,600
6,700
1/1/1988 1/1/1992 1/1/1996 1/1/2000 1/1/2004 1/1/2008
Wat
er e
leva
tion
(ft a
.m.s
.l.)
NA-37A NA-37B NA-37C
NA-37 simulated, layer 1 NA-37 simulated, layer 2 NA-37 simulated, layer 4
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Flow Model – Transient (Infiltration Basin) Flow Model – Transient (Infiltration Basin)
4700
4720
4740
4760
4780
4800
4820
4840
4860
4880
1/1/1988 1/1/1992 1/1/1996 1/1/2000 1/1/2004 1/1/2008
Wat
er e
leva
tion
in ft
a.m
.s.l.
NA-14
NA-14 simulated, layer 1
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Flow Model – Transient (Surface Water) Flow Model – Transient (Surface Water)
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Flow Model – ProjectionFlow Model – Projection
3600
3700
3800
3900
4000
4100
4200
4300
4400
4500
4600
4700
4800
4900
5000
5100
5200
0 50 100 150 200 250 300 350 400
Stag
e in
feet
(am
sl)
Recovery Time in Year
Simulated Pit Stage
Groundwater level
Pit water stage
Post-Mining Pit Lake Recovery
Simulated Maximum Drawdown (10 feet)
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5. Conclusions5. Conclusions
• Groundwater pumping at Goldstrike has resulted in 520 m of drawdown around the mine site.
• Most of the water pumped at the mine has been returned to the same hydrologic basin.
• Extensive monitoring program, assisted by modern satellite technology and by robust modeling, has identified aquifer responses.
• Improvement of the water-management system, the monitoring network, the modeling and analysis continue at Goldstrike.
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April 3-5, 2012 U.S. EPA Hardrock Mining Conference 2012
Thank You for Your Attention!Thank You for Your Attention!
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