Mine Dewatering and Water Management at Barrick … Dewatering and Water Management at Barrick...

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

2

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

U.S. EPA Hardrock Mining Conference 2012 3

1. Introduction – Barrick

April 3-5, 2012 U.S. EPA Hardrock Mining Conference 2012 4

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

April 3-5, 2012 5U.S. EPA Hardrock Mining Conference 2012


1. Introduction – Goldstrike Mine1. Introduction – Goldstrike Mine

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Open PitOpen Pit

400 m400 m

3,700 m3,700 m

2,000 m2,000 m

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Underground MinesUnderground Mines

Pre-mining water table1600 m amsl

Current water table1100 m amsl with a drawdown of 500 m

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2. Goldstrike Dewatering System2. Goldstrike Dewatering System

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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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Dewatering System - ActiveDewatering System - Active

Piezometer

Local WellRegional Well

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Dewatering System - PassiveDewatering System - Passive

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Dewatering System - PassiveDewatering System - Passive

HD (1994 – 2002)• Numbers: 1800

• Length: 10 – 450 m

•Total Length: 380 km

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Water Management System Water Management System

560,000 m2/Each

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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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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

April 3-5, 2012 18U.S. EPA Hardrock Mining Conference 2012

From Massonnet, 1997


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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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



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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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Thank You for Your Attention!Thank You for Your Attention!

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Mine Dewatering and Water Management at Barrick … Dewatering and Water Management at Barrick...

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