hydrogeology overview v3
DESCRIPTION
Overview – Hydrogeology ITRANSCRIPT
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SchoolofMiningEngineering
HydrogeologyIforMINE8760
Dr WendyTimms
[email protected]://research.unsw.edu.au/people/drwendytimmsApril2012
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Overview HydrogeologyI
1. Watercycle&surfacehydrology waterbalancecomponents,waterusers
2. Subsurfacewater(hydrogeology) porosity,vadose zone,aquifer,aquitard,aquicludes specificyield,storativity
3. Excess&shortagesofminewater classesofwater,sitewateraccounting
4.Waterquality salinity,acidity(AMD),metals,organics,microbiological biologicalmonitoringofwatersreceivingdischarge wastecontainment&closure
5.Basicmonitoring6. Casestudies nosignificantimpact&significantimpact7. Casestudy GympieEldoradoGoldMine
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SuggestedReadings:
Hair,I,2003.Groundwaterissuesintheminingindustry.AusIMMWaterinMiningConference,Brisbane,1315October2003.
Hebblewhite,2009.OutcomesoftheindependentinquiryintoimpactsofundergroundcoalminingonnaturalfeaturesintheSouthernCoalfield Anoverview.UndergroundCoalOperatorsConference,UniversityofWollongong.
Textbook (ifyouwantmoredetail!)
Domenico andSchwartz,1998.Physicalandchemicalhydrogeology.2nd Edition,NewYork:Wiley
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Sourcesforthispresentation
Mainsources:www.nwc.gov.au
UNSWwww.connectedwaters.unsw.edu.au
SCCGGroundwaterManagementHandbookhttp://www.sydneycoastalcouncils.com.au/node/71
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1.Thewatercycle
95% of global unfrozen fresh water is groundwater
Factsheet GroundwaterMythshttps://www.connectedwaters.unsw.edu.au/resources/fact/groundwater_myths.html
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1.Thewatercycle
GroundwaterisanintegralpartofthewatercycleorhydrologicalcycleGroundwatermovesveryslowly 150m/yearthroughtheBotanysandaquifer,and
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1.Waterusebyminingincontext
95%ofglobalunfrozenfreshwaterisgroundwater
21%ofAustraliaswateruseisgroundwater
2%Australianwaterusebymining
67%ofAustralianwaterusebyagriculture
21%ofagriculturalwaterisgroundwater
15%ofagriculturalwaterusebycotton
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1.Waterusevs.productivity
1
10
100
1000
10000
direct per %GNE/GNT
Litresvs.%GNE/GNTlogscale
CSIRO&UniversityofSydney,2005http://www.csiro.au/Outcomes/Environment/PopulationSustainability/BalancingAct.aspx
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1.Wateruse detailsformining&CSG
Butyoucanteatmoney(orrocks)
andyoucantcookwithoutenergy(orminerals)
0
5
10
15
20
25
direct per % GNE/GNT
total per % GNE/GNT
Litres vs. % GNE/GNT linear scale
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1.WateruseinNSWmineralsindustry
WateruseintheNSWmineralsindustry:http://www.nswmin.com.au/PolicyandAdvocacy/Environment/Water/Water/default.aspx Watersources Watermanagement Regulationofwateruse Waterdischarges Effectsofminingonwaterresources
CaseStudy SpringvaleCoal DeltaElectricityWaterTransferScheme
CaseStudy Northparkes Mine:RioTintoFloatingModule reduceevaporativelosses
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3.Minewater leadingpractice
Rapidchangesandadditions!
AustralianGovernmentinformationformining:http://www.ret.gov.au/resources/resources_programs/lpsdpmining/pages/default.aspx
Aguidetoleadingpracticesustainabledevelopinginmining(Laurence,2011 UNSWMiningEngineering&ACSMP)http://www.ret.gov.au/resources/Documents/LPSDP/guideLPSD.pdf
Leadingpracticesfortheminingindustry watermanagement(Gibsonetal2008)http://www.ret.gov.au/resources/Documents/LPSDP/LPSDPWaterHandbook.pdf
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3.Minewater potentialimpacts
Rapidchangesandadditions!
NSWGovernment draftguidelinesforAquiferInterference(March,2012)http://www.water.nsw.gov.au/Watermanagement/Lawandpolicy/Legalreform/Legalreform
NationalWaterCommission:Potentiallocal&cumulativeimpactsofminingongroundwaterresources
(SKM20102011seriesofreports)http://nwc.gov.au/rnws/groundwaterprojects/strategicaquifercharacterisationtoquantifysustainableyields/potentiallocalandcumulativeimpactsofminingongroundwaterresources
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1.Energycostsforwatersupply
NeedtoconsiderfullLCA(lifecycleassessment)includingcostsofinvestigation,capital,operatingexpensesanddesignlife.
Location Water supply kWh per kilolitre
Sydney Deep groundwater (fractured sandstone, 60 m head, 25 ML/day)
~0.4
Shallow groundwater (sand aquifer)
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2.Waterbelowtheground
Groundwaterisfoundinpores,cracksandcrevicesunderground
Groundwaterisinthesaturatedzoneofthesubsurface
Vadose waterSoilwaterUnsaturatedzoneWatertableCapillaryzoneSaturatedzone
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2.Waterstoredinporousspaces
Material Porosity (%)
Specific Yield (%)
Volume (L) in 1 m of aquifer
Gravel 25 - 40 15 35 150 - 350
Sand 25 - 50 20 45 200 450
Silt 35 - 50 < 5 < 50
Clay 40 - 70 < 1 < 10
Sandstone 5 - 30 5 15 50 150
Limestone, Dolomite 0 - 20 5 7 50 - 70
Relationship between Porosity and Specific Yield
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2.Terminology
Aquifer saturatedsedimentsorrockfromwhichgroundwatercanbeextractedAquitard saturatedsedimentorrockoflowpermeabilitywhichwatercanflowslowlyAquiclude impermeablesedimentorrockthroughwhichwatercannotflow
Artesian borewithapressuresurfaceabovethegroundallowingwatertoflowwithoutpumping
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2.TypesofAquifers
Unconfinedaquifer Watertabledefinesboundary
betweenunsaturatedandsaturatedzoneatwhichpressureisatmospheric
Confinedaquifer Groundwaterrisesinaboreabove
thetopoftheaquiferasapressureorpotentiometriclevel
Perchedaquifers
Source: SCCG Groundwater Handbook
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$Valueofgroundwaterstorage
1 km2
30% porosity
5 m Water-tablerange30 m
Aquiferthickness
Dynamic volume = 1500 ML per km2 ~$2 million per km2 @ $1.25 /KL
+ Environmental Values for Groundwater Dependent Ecosystems+ Social Values such as amenity of Centennial Park
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3.Excesses&shortagesofminewater
Typesofwateratminesites Runoffwater,groundwater,environmentalwaters(receptorsfordischarge) Supplywaterfitforuse drinking,washing,operations Processwater,wastewater possiblyrequirestreatment Recycledwater treatedfitforpurpose agrowthopportunity! Entrainedwater inproductandwaste(virtualwater)
Waterisoftenacriticalfactorforminingproductivity Delaysduetoexcessofwater dewateringnoteffectiveorfloodingofpit Shortageofwaterforprocessing,dustsuppressionetc.
Eg.Rangermine,NT,productionstoppedformonthsduetofloodingofpitduringCycloneandyearsofaboveaveragerainfall,significanteconomicimpact.
Eg.$100millionperdayoflostproductioninQLDcoalmineswith20112012floods
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Sourcesofcontaminatedwateronminesites
Pitandundergrounddewatering Processwaterstorage Seepageoroverflow Pits
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Monitoringwastewateratminesites
Physio-chemical monitoring
Use of on site & laboratory water testing selected parameters
Identification of specific tracers Identify presence of toxic species
To establish water quality criteria for protection of aquatic ecosystems need to measure a wide range of parameters initially
Biological monitoring
Use of aquatic fauna assemblages Toxicity testing of effluent Bioaccumulation of contaminants
Such tests give a more realistic assessment of the effects of waste water on aquatic biota
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FactorsassociatedwithbestpracticeprinciplesMethodsofwaterrelease
Undertake stream gauging and measure flow
Collect rainfall and evaporation data Make precise catchment delineation Understand other sources of water eg
ground water Catchment runoff coefficients
Such data needed to quantify loads of constituents and apply water management procedures
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FactorsassociatedwithbestpracticeprinciplesWaterdischargecriteria(ANZECC2000)
Go through ANZECC process and determine environmental values
Determine suitable sampling sitesAcquire baseline data
Following commencement of mining:
Characterise waste water (ICP MS scan)
Undertake detailed catchment modelling
Undertake pre-release toxicity testing
Undertake aquatic assemblages survey
Undertake bio-accumulation studies with organisms
http://www.environment.gov.au/water/policy-programs/nwqms/
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3.Minesitewateraccounting
Inventoryofwaterstorageandflowsinallpartsofoperations Wateraccountingrequiredfor:
efficientoperation riskmanagement regulatoryapprovals communityrelations
Softwarepackagesavailable GOLDSIMTM,OPSIMTM
Newwateraccountingtoolsavailableonweb:WaterMiner,WaterValueTool,CumulativeImpactsAssessmentToolhttps://www.cwimi.uq.edu.au/OurResearch/Tools.aspx
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4.Waterquality&mining
Classificationofwaterquality(commonminewaterissuesinred) Grosspollutantseg.Leaves,cigarettebutts Suspendedmattereg.turbidity,TSS pH acidityoralkalinity Temperature Salts eg.Sodium,sulphate,chloride oftenasignificantissueinAustralia Metals eg.Arsenic,lead Organicseg.Polycyclichydrocarbons(PAH),BTEX Dissolvedgases Microbiologicaleg.E.Coli
Leadingpracticeguidelineformanagingaciddrainage(2007)http://www.ret.gov.au/resources/Documents/LPSDP/LPSDPAcidHandbook.pdf
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5.Basicgroundwatermonitoring
Factsheetonbasicmonitoringhttps://www.connectedwaters.unsw.edu.au/resources/fact/diy_monitoring.html
Groundwaterlevel automatedpressureloggersGroundwaterquality rangeofparametersGroundwateruse flowgauge
Monitoringboredesign&installation
Whatsampling&monitoringequipmentisneeded?
Howoftentomonitor?
Groundwatersampling&analysis afieldguide(GeoscienceAustralia,Sundarametal,2009)http://www.ga.gov.au/image_cache/GA15501.pdf
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5.Basicgroundwatermonitoring
Factsheet on basic monitoringhttps://www.connectedwaters.unsw.edu.au/resources/fact/diy_monitoring.html
Monitoring bore(or piezometer)
Pumping bore
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Watermonitoringaroundaminesite
Surfacesites Targetsmultipleaquifersat
variousdepths
Controlsites up&downhydraulicgradientbeyondimpactofmine
Sitesbetweenmineandsensitiveareas(eg.wetlands)
Longtermbaselinesitesvs.replacesitesthatarelostduringproduction
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Sitewatermanagement
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6.Casestudies nosignificantwaterimpact?
Veryfewreportedcases why?Whatisnotsignificant?
BrokenHillmines,Kalgoorliemines muchofAustraliaswealth GunnedahPrestoncoalmines u/g&openpitfromfarmersdiscoveryin1895until1998
whenreservesexhausted LakeMunmorahcoalmine miningunderlargewaterbody Potashmining,Canada deepundergroundminingalongsidewheatcropping Diavik diamondmine,northernCanada cutoffwallswithin~12mdeeplake
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6.Casestudies significantwaterrisks
Reportedcasesareapparentlyincreasing why? Whatissignificant?
LongwallcoalmininginSydneyBasin Impactsoncreeks&groundwaterisagrowingconcern NSWPlanningAssessmentCommissionreports Bulliseam,SouthernCoalfields,Wyong SCS,2007.Literaturereviewlongwall mining TEC,2007.Impactsofcoalminingontheenvironment Mills,2008.MineSubsidenceTechnologicalSociety,UniversityofWollongong Reading Hebblewhite,2009,AusIMM Coaloperatorsconference
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Casestudies significantwaterrisksReportedcasesareapparentlyincreasing why? Whatissignificant?
RumJungleuraniumminerehabilitation,NT Mined19531963,rehabilitation19821986:$18.1million,2009:$8.3millioncommitted AciddischargewithCu,Pb,Ni,U,exceedcurrentguidelines,increasingleakageofcaps.
EnvironmentalPollution,158(2010)12521260
Lusi mudvolcano,Indonesia Explorationboredrillingin2006,anearthquakeandmudvolcanoerupting200maway,stillflowing
in2011,buryingvillagesandfields.Causesandliabilityareunresolved,poordrillingpracticesappeartohavesignificantlyincreasedrisks
MarineandPetroleumGeology27(2010)16511657&16581675
Mineclosurebeforereservesexhausted 3%mineclosuresduetoflooding/wetweather 6%ofprematuremineclosuresduetoenvironmentalissues Reading Laurence,D.JournalofCleanerProduction19(2011)278284
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Thankyou
Youarewelcometoemailqueries,[email protected]
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ExcessWaterAccumulation
Gympieexperiencedwetweatherfor2yearsfromAugust1998MidFeb1999equalrecordfloodadded259MLtotailingsdam(capacity450ML)ApproachtoMinisterforMines7April1999whorequestedscientificstudies,close
consultationwithstakeholdersandothergroupstodevisecontrolleddischargeplan
GympieEldoradoGoldMineanundergroundmineandmillNearbyGympie21000peoplemixedeconomy,rangeofnonminingactivitiesMiningencountersgroundwaterwith0.9MLpumpedtoMaryRiverINCOprocessdestroyscyanidebeforepumpingtostorage
CaseStudy GympieEldoradogoldmine
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ApproachTakenDraftplandevisedbyauthorsCompanysoughttooperatewithinthenewANZECC(2000)guidelinesArsenic,cyanide,mercuryandotherheavymetalswellwithinANZECC1992
guidelinesConsultationwithcommunitygroupsJulySept1999gavefeedbackFinalplanapprovedSept1999for350MLover9monthperiodcommencing
October1999
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0.12
157
17.73
2.09 0.310
20
40
60
80
100
120
140
160
180
100m upstream Pipeline 0m downstream 10m downstream 50m downstream
Water source
ANZECC GUIDELINE FOR ECOSYSTEM PROTECTION = 30 ug/L
Concentration (g/L) of antimony upstream, at the point of discharge and downstream.
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StudiesPriortoReleasePre release testing of watersLaboratory studies using 2
crustacean species Daphnia carinata Paratya australiensis
Bioassay data supported a dilution of 1:20 causing no adverse effects
Comprehensive identification of contaminants Antimony a limiting constituent Nitrate may be limiting Proposed a safe dilution of 1:20
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StudiesundertakenduringreleaseCommencementofrelease
Release water was pre-mixed tailings and mine dewatering 2:1Quality monitoring of resultsIn stream validation 2 tests applied
Laboratory bioassay with Paratya In situ bioassay
Characteristics of discharge Conductivity profile Chemical analysis of test and discharge water
Summary
General features of dischargeSignificance of controlling physico-chemical variablesSignificance of bioassay and in stream validation
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312 309 312
435
1072
380336 319 313 316 314 349
0
200
400
600
800
1000
1200
+100 +30 +15 +10 0 -5 -10 -20 -50 -100 -500 -1000
Distance in meters (not to scale)
C
o
n
d
u
c
t
i
v
i
t
y
(
u
s
/
s
e
c
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Conductivity measured upstream and downstream of discharge point. Positive values are upstream and negative values are downstream from discharge.
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03.29
0.290.04 0
0
0.5
1
1.5
2
2.5
3
3.5
4
100m upstream Pipeline 0m downstream 10m downstream 50m downstream
water source
g
o
l
d
(
u
g
/
L
)
Concentration of gold upstream, at the point of discharge and downstream