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Overview – Hydrogeology I

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  • SchoolofMiningEngineering

    HydrogeologyIforMINE8760

    Dr WendyTimms

    [email protected]://research.unsw.edu.au/people/drwendytimmsApril2012

  • 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

  • SuggestedReadings:

    Hair,I,2003.Groundwaterissuesintheminingindustry.AusIMMWaterinMiningConference,Brisbane,1315October2003.

    Hebblewhite,2009.OutcomesoftheindependentinquiryintoimpactsofundergroundcoalminingonnaturalfeaturesintheSouthernCoalfield Anoverview.UndergroundCoalOperatorsConference,UniversityofWollongong.

    Textbook (ifyouwantmoredetail!)

    Domenico andSchwartz,1998.Physicalandchemicalhydrogeology.2nd Edition,NewYork:Wiley

  • Sourcesforthispresentation

    Mainsources:www.nwc.gov.au

    UNSWwww.connectedwaters.unsw.edu.au

    SCCGGroundwaterManagementHandbookhttp://www.sydneycoastalcouncils.com.au/node/71

  • 1.Thewatercycle

    95% of global unfrozen fresh water is groundwater

    Factsheet GroundwaterMythshttps://www.connectedwaters.unsw.edu.au/resources/fact/groundwater_myths.html

  • 1.Thewatercycle

    GroundwaterisanintegralpartofthewatercycleorhydrologicalcycleGroundwatermovesveryslowly 150m/yearthroughtheBotanysandaquifer,and

  • 1.Waterusebyminingincontext

    95%ofglobalunfrozenfreshwaterisgroundwater

    21%ofAustraliaswateruseisgroundwater

    2%Australianwaterusebymining

    67%ofAustralianwaterusebyagriculture

    21%ofagriculturalwaterisgroundwater

    15%ofagriculturalwaterusebycotton

  • 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

  • 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

  • 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

  • 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

  • 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

  • 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)

  • 2.Waterbelowtheground

    Groundwaterisfoundinpores,cracksandcrevicesunderground

    Groundwaterisinthesaturatedzoneofthesubsurface

    Vadose waterSoilwaterUnsaturatedzoneWatertableCapillaryzoneSaturatedzone

  • 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

  • 2.Terminology

    Aquifer saturatedsedimentsorrockfromwhichgroundwatercanbeextractedAquitard saturatedsedimentorrockoflowpermeabilitywhichwatercanflowslowlyAquiclude impermeablesedimentorrockthroughwhichwatercannotflow

    Artesian borewithapressuresurfaceabovethegroundallowingwatertoflowwithoutpumping

  • 2.TypesofAquifers

    Unconfinedaquifer Watertabledefinesboundary

    betweenunsaturatedandsaturatedzoneatwhichpressureisatmospheric

    Confinedaquifer Groundwaterrisesinaboreabove

    thetopoftheaquiferasapressureorpotentiometriclevel

    Perchedaquifers

    Source: SCCG Groundwater Handbook

  • $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

  • 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

  • Sourcesofcontaminatedwateronminesites

    Pitandundergrounddewatering Processwaterstorage Seepageoroverflow Pits

  • 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

  • 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

  • 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/

  • 3.Minesitewateraccounting

    Inventoryofwaterstorageandflowsinallpartsofoperations Wateraccountingrequiredfor:

    efficientoperation riskmanagement regulatoryapprovals communityrelations

    Softwarepackagesavailable GOLDSIMTM,OPSIMTM

    Newwateraccountingtoolsavailableonweb:WaterMiner,WaterValueTool,CumulativeImpactsAssessmentToolhttps://www.cwimi.uq.edu.au/OurResearch/Tools.aspx

  • 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

  • 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

  • 5.Basicgroundwatermonitoring

    Factsheet on basic monitoringhttps://www.connectedwaters.unsw.edu.au/resources/fact/diy_monitoring.html

    Monitoring bore(or piezometer)

    Pumping bore

  • Watermonitoringaroundaminesite

    Surfacesites Targetsmultipleaquifersat

    variousdepths

    Controlsites up&downhydraulicgradientbeyondimpactofmine

    Sitesbetweenmineandsensitiveareas(eg.wetlands)

    Longtermbaselinesitesvs.replacesitesthatarelostduringproduction

  • Sitewatermanagement

  • 6.Casestudies nosignificantwaterimpact?

    Veryfewreportedcases why?Whatisnotsignificant?

    BrokenHillmines,Kalgoorliemines muchofAustraliaswealth GunnedahPrestoncoalmines u/g&openpitfromfarmersdiscoveryin1895until1998

    whenreservesexhausted LakeMunmorahcoalmine miningunderlargewaterbody Potashmining,Canada deepundergroundminingalongsidewheatcropping Diavik diamondmine,northernCanada cutoffwallswithin~12mdeeplake

  • 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

  • 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

  • Thankyou

    Youarewelcometoemailqueries,[email protected]

  • ExcessWaterAccumulation

    Gympieexperiencedwetweatherfor2yearsfromAugust1998MidFeb1999equalrecordfloodadded259MLtotailingsdam(capacity450ML)ApproachtoMinisterforMines7April1999whorequestedscientificstudies,close

    consultationwithstakeholdersandothergroupstodevisecontrolleddischargeplan

    GympieEldoradoGoldMineanundergroundmineandmillNearbyGympie21000peoplemixedeconomy,rangeofnonminingactivitiesMiningencountersgroundwaterwith0.9MLpumpedtoMaryRiverINCOprocessdestroyscyanidebeforepumpingtostorage

    CaseStudy GympieEldoradogoldmine

  • ApproachTakenDraftplandevisedbyauthorsCompanysoughttooperatewithinthenewANZECC(2000)guidelinesArsenic,cyanide,mercuryandotherheavymetalswellwithinANZECC1992

    guidelinesConsultationwithcommunitygroupsJulySept1999gavefeedbackFinalplanapprovedSept1999for350MLover9monthperiodcommencing

    October1999

  • 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.

  • 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

  • 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

  • 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

    )

    Conductivity measured upstream and downstream of discharge point. Positive values are upstream and negative values are downstream from discharge.

  • 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