mine closure and sustainable water management by prof carolyn oldham
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Mine closure and sustainable water management
Prof. Carolyn OldhamSchool of Environmental Systems Engineering
Mine Lake 116Central German coal district
Island Copper LakeBritish Columbia, Canada
Photo: T. Fischer
Lake StocktonCollie coal district
Lake StocktonCollie coal district
Gravel pitCentral German coal district
Chicken Creek Pit, Collie Coal Basin
Sustainable water management
• Optimisation:– Impact on downstream water resources– Impact on environment– Beneficial end uses – Social impact– Ongoing management costs– Mine operations
• Unlikely to be a “walk-away” solution
Outline
• Mine life stages
• Conceptual model
• Water balances
• Water quality modelling
• Validation
• AMCER Protocol
Phases of mine life
Island Copper LakeBritish Columbia, Canada
Photo: T. Fischer
1. Collate any existing site data
Exploration data, decision:Mine feasible
2. Site-specific conceptual model
5. Design and begin data collection program
4. Assess potential environmental impact and end uses
7. As input data collected, update predictions
WQ“poor”
No solution: reassess?
1. Mine plan, history
General conceptual
model
6. Document all data, calculations (+assumptions), sampling plan
8. As external and internal validation data collected, test prediction;
if necessary, improve
Goal: pit lake with beneficial end uses or acceptable impact for
minimum cost
WQ good/ impact acceptable
4. Scenario testing: - prevention possible?- remediation possible?- backfilling feasible?- downstream mitigation?
3. Quantify/predict likely WQ evolution
WQ modelling
tools
Flow chart of mine water assessment
Development of a hydrological conceptual model
Development of a lake conceptual model
Island Copper LakeBritish Columbia, Canada
Bathymetry
Bathymetry - landscaping
WO5BCollie, Australia
Meteorological data
Island Copper LakeBritish Columbia, Canada
Photo: T. Fischer
Mass balances - groundwater inflow
Chicken CreekCollie, Australia
Mass balances - inputs from surface runoff
1. Collate any existing site data
Exploration data, decision:Mine feasible
2. Site-specific conceptual model
5. Design and begin data collection program
4. Assess potential environmental impact and end uses
7. As input data collected, update predictions
WQ“poor”
No solution: reassess?
1. Mine plan, history
General conceptual
model
6. Document all data, calculations (+assumptions), sampling plan
8. As external and internal validation data collected, test prediction;
if necessary, improve
Goal: pit lake with beneficial end uses or acceptable impact for
minimum cost
WQ good/ impact acceptable
4. Scenario testing: - prevention possible?- remediation possible?- backfilling feasible?- downstream mitigation?
3. Quantify/predict likely WQ evolution
WQ modelling
tools
Flow chart of mine water assessment
Water balances - inputs
Water balance - outputs
Water balance
Huber et al. 2008
Meteorological data
Impact of wind speeds on water balance
Impact of wind sheltering on water levels
100% surface wind speed
10% surface wind speed
Huber et al. 2008
Effect of wind on stratification
Effect of wind sheltering on stratification
DYRESM - 100% surface wind speed
DYRESM - 10% surface wind speed
1. Collate any existing site data
Exploration data, decision:Mine feasible
2. Site-specific conceptual model
5. Design and begin data collection program
4. Assess potential environmental impact and end uses
7. As input data collected, update predictions
WQ“poor”
No solution: reassess?
1. Mine plan, history
General conceptual
model
6. Document all data, calculations (+assumptions), sampling plan
8. As external and internal validation data collected, test prediction;
if necessary, improve
Goal: pit lake with beneficial end uses or acceptable impact for
minimum cost
WQ good/ impact acceptable
4. Scenario testing: - prevention possible?- remediation possible?- backfilling feasible?- downstream mitigation?
3. Quantify/predict likely WQ evolution
WQ modelling
tools
Flow chart of mine water assessment
Mass balances - AMD from walls
Chicken CreekCollie, Australia
Mass balances - AMD from overburden runoff
Chicken CreekCollie, Australia
Surface inflow assumptions
CAEDYM - Fe(III) and Fe(II) – assuming 100% seepage through black shale
CAEDYM - Fe(III) and Fe(II) – assuming 10% seepage through black shale
During Filling Monitoring
• Geochemical characterisation of mine void and surrounds, to determine changes in contaminant release
• Changing pit bathymetry
• On-site meteorological forcing
• Establish current and predicted mass balances
• On-site water column sensor chains
• Water quality sampling
Island Copper LakeBritish Columbia, Canada
Mass balances - inflows
Photo: T. Fischer
On-site water column sensor chains
Photo: T. Fischer
On-site water column sensor chains
WO5BCollie, Australia
river diversion
LDS data, Oct 2003LDS data, Oct 2003--May 2005May 2005
Lake KepwariCollie, Australia
Post-filling Monitoring
• Geochemical characterisation of local mineralogy
• Geochemical characterisation of source waters
• On-site meteorological forcing
• Establish current and predicted mass balances
• On-site water column sensor chains
• Water quality sampling
Water quality sampling
temperature, salinity,
dissolved oxygen pH
turbidity
T salinity DO% sat
LakeKepwariCollie coal istrict
Water quality sampling
LakeKepwariColliecoal district
Water quality sampling
river diversion
LDS data, Oct 2003LDS data, Oct 2003--May 2005May 2005
Water quality sampling
Water Quality Modelling
• Range of models– Lake stratification models– Geochemical models– Ecological models
All require input data
Field
DYRESM
Model validation
Forward prediction - 10 year
Where to start
Oldham et al., ACMER Protocol
Where to start
Oldham et al., ACMER Protocol
1. Collate any existing site data
Exploration data, decision:Mine feasible
2. Site-specific conceptual model
5. Design and begin data collection program
4. Assess potential environmental impact and end uses
7. As input data collected, update predictions
WQ“poor”
No solution: reassess?
1. Mine plan, history
General conceptual
model
6. Document all data, calculations (+assumptions), sampling plan
8. As external and internal validation data collected, test prediction;
if necessary, improve
Goal: pit lake with beneficial end uses or acceptable impact for
minimum cost
WQ good/ impact acceptable
4. Scenario testing: - prevention possible?- remediation possible?- backfilling feasible?- downstream mitigation?
3. Quantify/predict likely WQ evolution
WQ modelling
tools
Flow chart of mine water assessment
The team
Team leaders Carolyn OldhamGreg IveyJason Plumb, CSIRO
Research Assoc.BibhashNathUrsula Salmon
Matt Hipsey, CWRGeoff Wake
PhD students Deborah ReadHuynh Pham
Masters students Anita HuberAlisa Krasnostein
Honours students Emma CravenPeter ChapmanTung Nguyen
ManuellaSusantoAlice TurnbullTom ZdunAaron Brunt
The funding
Australian Research Council
ACMERCentre for Sustainable
Mine LakesState Government of
Western AustraliaWesfarmers Premier CoalGriffin CoalSons of GwaliaCollie Shire CouncilUniversity of Western
Australia
Thank you