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2006 MEADOWBANK GOLD PROJECT Cumberland Resources Ltd. Final Hearings – Baker Lake, Nunavut March 27 to March 31, 2006 OVERVIEW OF BASELINE STUDIES  Permafrost.

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Presentation on theme: "2006 MEADOWBANK GOLD PROJECT Cumberland Resources Ltd. Final Hearings – Baker Lake, Nunavut March 27 to March 31, 2006 OVERVIEW OF BASELINE STUDIES  Permafrost."— Presentation transcript:

1 2006 MEADOWBANK GOLD PROJECT Cumberland Resources Ltd. Final Hearings – Baker Lake, Nunavut March 27 to March 31, 2006 OVERVIEW OF BASELINE STUDIES  Permafrost  Geochemistry  Water Quality and Quantity PROJECT ALTERNATIVES  All Weather Road Alternatives  Waste Management Alternatives  Dewatering Dike Construction Alternatives

2 2006 MEADOWBANK GOLD PROJECT Overview of Baseline Studies Thermal Regime and Permafrost

3 2006  Site located in the Low Arctic Ecozone Cold and dry climate  The design of the mine system, including waste management plan, requires an understanding of: –Permafrost depth and temperature –Active layer depth and variability across the site –Talik development adjacent to and beneath lakes –Specific site structures MEADOWBANK GOLD PROJECT Thermal Regime and Permafrost Key Considerations for Cold Regions

4 2006  MEADOWBANK GOLD PROJECT Thermal Regime and Permafrost Permafrost Map of Canada

5 2006  10 years of baseline thermal data  22 Thermistors strings at the site  206 total individual temperature monitoring points MEADOWBANK GOLD PROJECT Thermal Regime and Permafrost Thermistor Location Plan

6 2006  10 years of baseline thermal data  Currently, 22 Thermistors strings installed at the site with a total of 206 individual temperature monitoring points MEADOWBANK GOLD PROJECT Thermal Regime and Permafrost Cross Section through Deposit Areas

7 2006 MEADOWBANK GOLD PROJECT Thermal Regime and Permafrost Baseline Thermal Conditions

8 2006  Site underlain by continuous permafrost to depth of up to 530 m depending on proximity to lakes  Permafrost temperature -7 to -8 ۫ C at depth of zero annual amplitude (>250 m from lake)  Active layer depth range from 1.3 to 4.0 m  Mathematical Solutions and thermal modelling indicate Taliks extending through permafrost exist beneath circular lakes > 570 m diameter and elongated lakes with width > 320 m  Mean Annual Air Temperature to o C MEADOWBANK GOLD PROJECT Thermal Regime and Permafrost Summary of Permafrost Regime

9 2006 Overview of Baseline Studies Geochemistry, Groundwater Quality and Quantity MEADOWBANK GOLD PROJECT

10 2006 Geochemistry Overview of Baseline Studies MEADOWBANK GOLD PROJECT

11 2006 Meadowbank Geology Goose Island Deposit

12 2006 Meadowbank Geology Vault Deposit

13 2006 Baseline Geochemical Sampling

14 2006 Pit Rock Core IF IV UM

15 2006 Rock Testing Program 500 kg field cells 100 kg Laboratory columns 1 kg samples Varied Scales:

16 2006 Tailing Testing Program  Portages, Goose, Vault ore: Flotation, concentrate and re-combined  Composite: Mix Portage-Goose-Vault, Cyanide destroyed tails  Tailing porewater From metallurgical program Au

17 2006 Soils  R.C. surface drilling program (> 400 samples) soil type, chemistry, sulphides  11 Surface samples Goose, Third-North Portage, airstrip chemistry, ARD, leachable metals

18 2006 Mine Area Surface Drainage Water (Map of samples)

19 2006 Exploration Trench Water (Photo of trenches close-up and aerial) Third Portage mineral deposit

20 2006 Trench Water Sampling Portage Vault

21 2006 Rock Geology, Mineralogy Goose Island, Third, North PortageVault Intermediate Volcanic Iron FormationUltramaficQuartzite Intermediate Volcanic 28%35% 2%100% geologyVolcaniclastic tuffs, greywacke oxide-facies banded iron formation amphibolite, komatiite, mafic to UM Sedimentary quartzite volcanic tuffs, greywacke mineralogyquartz, feldsp. muscovite, chlorite quartz, magnetite, amphibole, chlorite talc, chlorite, dolomite quartzquartz, muscovite, chlorite, dolomite carbonatescalcite, dolomite, minor siderite trace calcitedolomite, calcite, some siderite nonedolomite, calcite average NP* Average sulphide 0.26%1.2%0.2%0.45%0.75% *Neutralisation potential (NP) in kg calcium carbonate equivalent per tonne of rock

22 2006 ARD criteria, INAC 1992 Goose Portage Vault 35 % 28 % 35 % 2 % 100 % Results - Rock ARD Potential

23 2006 Results of Baseline Studies  Pit rock, tailings : –possible ARD (portage), metals –Management options: cover-freezing, submergence  Tailings water: –As, Cu, Pb, Zn, Ni > MMER, ammonia, nitrates –Active treatment at end of mine life  Plant site (construction) rock, soil: –No ARD, low metals, unlimited use  Groundwater: –Chloride, TDS, low metals ( CCME)  Overland runoff: –Low metals, low pH (organic acids)

24 2006 Results – Rock Weathering Rates Arsenic

25 2006 Groundwater Quality and Quantity Overview of Baseline Studies MEADOWBANK GOLD PROJECT

26 2006 Groundwater Studies MEADOWBANK GOLD PROJECT Groundwater Quality Well LocationLithology Depth of Screened Zone GooseUM142 – 154 m GooseIF134 – 146 m North PortageIV102 – 113 m Second Portage LakeIV161 – 174 m

27 2006  Screen interval to be installed in thawed talik zone  Estimation of intersection with talik based on thermistor installations from lake shore, specifically data from Goose Island Pit Thermistor Groundwater Quality Baseline Studies Estimation of Thaw Bulb Location

28 2006 Groundwater Studies MEADOWBANK GOLD PROJECT Hydraulic Conductivity  No discernible variation in hydraulic conductivity (K) of the various rock types – Ultramafic, Iron Formation and Intermediate Volcanic have similar K – K decreases with depth regardless of rock type  Hydraulic conductivity with depth calculated as the geometric mean of packer tests over a given depth interval  Second Portage fault ~ 5 x10 -6 m/s  Bay Fault and Fault Splay ~3 x m/s

29 2006 Groundwater Studies MEADOWBANK GOLD PROJECT Shallow Groundwater Flow Regime  Characterized by falling head tests in till units Estimated 1 x to 3 x m/s Consistent with laboratory testing K=2 x to 4 x m/s  Based on thermistor data and model predictions active layer thawed from June to September ~1 to 4 m thick, but variable across site  Within the active layer water table will mimic topographic surface Groundwater in the active layer will flow to local depressions, ponds, and lakes

30 2006 MEADOWBANK GOLD PROJECT Groundwater Studies Existing Thermal/Hydrogeologic Regime Based on Site Data

31 2006  Characterized by over 75 hydraulic conductivity tests at: – Third Portage Deposit – North Portage Deposit – Third Portage Lake – Second Portage Lake  Deep groundwater flow is controlled by water levels in lakes with through-taliks  MODFLOW model developed for site – 34km by 40km centred on Portage – Permafrost thickness of 500 m assumed – Circular lakes > 570 m and elongate lakes > 320 m considered with through taliks Permafrost K zones Open Pits Dikes MEADOWBANK GOLD PROJECT Groundwater Studies Deep Groundwater Regime

32 2006 Groundwater Studies MEADOWBANK GOLD PROJECT Deep Groundwater Regime  Northwest portion of Second Portage Lake acts as a regional groundwater discharge zone

33 2006  TDS depth profile based on measured values and historical data of TDS/Cl profiles in the Canadian Shield  Salinity of groundwater expected to increase with depth  Monitoring wells at the site installed to 175m have [Cl] up to 626 mg/L and TDS to 800 mg/L. MEADOWBANK GOLD PROJECT Groundwater Studies Groundwater Salinity/Freezing Point Depression

34 2006 Groundwater Inflows to pits MEADOWBANK GOLD PROJECT Total Average Inflow  Modflow model pit inflows included inflows through Second Portage Fault Bay Zone Fault considered hydraulically insignificant Exclude precipitation, inflows from overburden, or dike seepage  Groundwater Inflows Goose Pit 400 m3/day ± 3 times 3rd and North Portage Pit 700 to 800 m3/day ± 3 times  TDS range predicted 500 mg/l to 800 mg/l Permafrost K zones Open Pits Dikes

35 2006 Project Alternatives MEADOWBANK GOLD PROJECT

36 2006  Initially 3 alternative access options considered: –Ice Road –Seasonal Land Road –Permanent All-Weather Road (AWR)  AWR selected based on environmental, technical, and economic considerations Project Alternatives – Access Road Land Route Alternatives MEADOWBANK GOLD PROJECT

37 2006 Project Alternatives – Access Road Permanent AWR Alternatives MEADOWBANK GOLD PROJECT  Three possible AWR evaluated –Initial screening resulted in selection of ‘Green’, or most westerly route Screening based on minimizing water crossings, and hence impact to fish habitat

38 2006 Project Alternatives – Access Road Permanent AWR Alternatives MEADOWBANK GOLD PROJECT  Once West route selected the following studies were completed: –Air photo assessment of geomorphology –Field verification of interpretation Mapping, soil and rock sampling, test pitting, lab testing (geotechnical and geochemical –Description of stream crossings –Map production Geomorphology, frost susceptibility, geology, quarry sample locations, photo locations –Geophysical survey Snow pack thickness and revision to route alignment

39 2006  Engineering studies underway to develop: –Finalized route selection –Road profile –Road structure –Material types –Abutment and river crossings  Will consider alternative crossing options to reduce impact to fish habitat  Continued interaction with DFO Project Alternatives – Access Road Permanent AWR Alternatives MEADOWBANK GOLD PROJECT

40 2006 Project Alternatives Waste Management Systems for Cold Regions MEADOWBANK GOLD PROJECT

41 2006 Site specific issues relating to facility location and relative land take;  Potential emissions of dust and effluents during operation (to air, land and water) and their impact;  Potential emissions of dust and effluents after closure (to air, land and water) and their impact;  ARD and metal leaching generation, release and impact;  Potential releases due to failures of facilities (i.e., burst or collapses of containment berms or dams); and  Site rehabilitation and aftercare to minimize environmental impacts. -European Commission, 2004: Best Available Techniques for Management of Tailings and Waste Rock in Mining Activities Project Alternatives – Waste Management Key Environmental Issues or Aspects to be Addressed MEADOWBANK GOLD PROJECT

42 Control of acid generating reactions; 2.Control migration of contaminants; and, 3.If required: Collection and treatment. Project Alternatives – Waste Management Cold Region Control Strategies for Mine Waste Disposal MEADOWBANK GOLD PROJECT

43 2006 Rock Storage Options  4 options evaluated for Portage Deposit Area Project Alternatives – Rock Storage Portage Area MEADOWBANK GOLD PROJECT

44 2006 Storage Options  4 options initially considered  Only 1 option, Option A, practical Low profile Consideration of migratory paths One catchment area Ease of operation Ease of closure Project Alternatives – Rock Storage Vault Area MEADOWBANK GOLD PROJECT

45 2006 Project Alternatives – Rock Storage Management Strategy MEADOWBANK GOLD PROJECT  Freezing of rock pile  Placement in lifts to promote freezing;  Convective cooling in coarse material  Progressive cover of Portage Rock Pile with non-PAG rock –2 m cover; but monitor water quality and thermal regime during operations to determine final cover thickness –Placement of some material back to pit  Vault not covered –Overall low potential for ARD –Monitor water quality and thermal regime for adaptive management –Attempt segregation of PAG to allow selective placement and surround by non-PAG –If necessary submergence of PAG in pit could be considered

46 2006  Initially 7 options evaluated  Slurry, paste, and dry stack tailings technologies considered A E B& C D D F& G Project Alternatives – Tailings Storage Portage Area MEADOWBANK GOLD PROJECT

47 2006  Options A, D, and E eliminated based on initial evaluation criteria  Remaining Options evaluated with process similar to Multiple Accounts Analysis  Key Indicators and sub-indicators identified  Relative weighting applied to the indicators to rank in relative order of perceived importance  Score applied to each sub-indicator based on scale of 1 to 9  Option C selected as best alternative Environment50% Operational30 % Economic20% Influence of Factors on Weighted Total Project Alternatives – Tailings Storage Initial Evaluation MEADOWBANK GOLD PROJECT

48 To evaluate the influence of relative weighting factors All weighting factors set to 1 to remove bias imposed by personal preference 2.To weight heavily to environmental factors Excluded economic factors completely Decreased influence of operational factors 3.To evaluate sensitivity of selection process to increased weighting of fish and fish habitat – Adjusted “number of lakes impacted” and “impact on fish habitat” to carry highest weighting 4.Replace habitat area (ha) of fish habitat and number of lakes affected by each option with true "habitat units" as derived in the No Net Loss report  Terrestrial habitat  Distinguish permanent from temporary habitat loss  Indicate “ Closure ” as a distinct sub-indicator.  Provide additional rationale for the categories and their rankings. Option C remained preferred Option in all Cases Project Alternatives – Tailings Storage Summary of Additional Sensitivity Evaluations MEADOWBANK GOLD PROJECT

49 Total freeze control strategy 2.Sub-aerial disposal in thin layers to promote freezing 3.Dispose into natural depression with permafrost surround for ease of long term monitoring, maintenance, and stability. 4.Cover at closure with non- PAG waste rock to minimize infiltration and to limit depth of thaw within the non-PAG cover. Project Alternatives – Waste Management Best Option - Tailings Disposal MEADOWBANK GOLD PROJECT

50 2006  Lowest potential for the generation of acidic drainage  Lowest potential for the generation of dust – lowest potential for the migration of contaminants beyond the limits of the storage facility and the mine site.  Construction materials from the mining activities  Closure methodology requires least amount of borrow materials  Low risk of instability of tailings facility, and hence lower risk of potential release of tailings to the environment  Precedence in Arctic climate  Flexibility for adaptive management Project Alternatives – Tailings Storage Advantages of Selected Site C MEADOWBANK GOLD PROJECT

51 2006 Project Alternatives Tailings Management MEADOWBANK GOLD PROJECT

52 2006 Project Alternatives – Tailings Storage Management Plan MEADOWBANK GOLD PROJECT  Dewater from El. 133 to 105 m (28 m) and construct Portage, Bay, and Starter Tailings Dike; Investigate fault in dike foundation  Year 1: Commence tailings discharge; operate attenuation pond separate from reclaim  Year 3: Construct stormwater dike; operate attenuation pond separate from reclaim  Year 5: Complete mining Goose Pit and start use as attenuation pond; former attenuation pond becomes reclaim  Year 8: Continue depositing tailings; operate reclaim and attenuation separately; begin treatment of reclaim water at end of mine life.  Closure: Complete cover of tailings, in-fill former reclaim pond with waste rock, cover, and freeze.

53 2006 Project Alternatives – Tailings Storage Tailings Facility – Year 1 MEADOWBANK GOLD PROJECT

54 2006 Project Alternatives – Tailings Storage Tailings Facility – Year 3 MEADOWBANK GOLD PROJECT

55 2006 Project Alternatives – Tailings Storage Tailings Facility – Year 5 MEADOWBANK GOLD PROJECT

56 2006 Project Alternatives – Tailings Storage Tailings Facility – Year 8 MEADOWBANK GOLD PROJECT

57 2006 Project Alternatives – Tailings Storage Tailings Facility – Closure Concept MEADOWBANK GOLD PROJECT

58 2006  Initially through talik beneath Second Portage Lake  Long term freezing of waste dumps and tailings impoundment area  Monitor rate of freezing during operations and use adaptive management to adjust closure plan –Mitigation strategies Enhanced freezing Cover design Lower tailings surface; consider tailings to Goose Pit Project Alternatives – Tailings Storage Tailings Facility – Closure Concept MEADOWBANK GOLD PROJECT Monitoring Well Thermistor Monitoring Well Thermistor Current Conditions Post Closure Conditions Waste Rock Pile Tailings

59 2006  Scenario 1 –Tailings mass considered frozen at start of model  0 °C and -1 °C isotherms in tailings and underlying rock with time Project Alternatives – Tailings Storage Tailings Facility Thermal Modeling MEADOWBANK GOLD PROJECT

60 2006 Project Alternatives – Tailings Storage Tailings Facility Thermal Modeling MEADOWBANK GOLD PROJECT  Scenario 2 –Tailings mass considered thawed at start of model  Tailings freeze for all modeled cases

61 2006 MEADOWBANK GOLD PROJECT Project Alternatives – Tailings Storage Summary of Key Issues and Adaptive Management Strategies  Monitoring wells and Thermistors –around tailings impoundment area –between the toe of the tailings dike and the pit –between the crest of the pit and the de-watering dikes.  Pit water will be monitored and managed. –Regular sampling and analysis of water –Review results –Adapt current plan as required  Monitoring of deep talik water beneath the tailings facility  Even if freezing of the tailings occurs at a lower rate than predicted, metal loadings are expected to be low.  If monitoring indicates that metal loadings are above predicted values then data will be reviewed and assessed –If loadings are low, then no action may be required. –Otherwise adaptive management strategies would be considered

62 2006 MEADOWBANK GOLD PROJECT Project Alternatives – Tailings Storage Groundwater Regime at Closure

63 2006 Project Alternatives Tailings Dike Design MEADOWBANK GOLD PROJECT

64 2006  8 geotechnical boreholes drilled in area SPT’s, moisture content, grainsize/hydrometer, packer testing, rock strength testing Project Alternatives – Tailings Dike Tailings Dike - Plan MEADOWBANK GOLD PROJECT

65 2006  Seepage cutoff element is compacted till membrane  Design does not rely on freezing to create barrier to seepage through dike  Contingency in place to grout fractured rock beneath dike  Low potential for fault re- activation due to age of faults, lack of evidence of past re- activation, and low seismic activity Project Alternatives – Tailings Dike Tailings Dike – Section Alternatives MEADOWBANK GOLD PROJECT

66 2006 Project Alternatives Mine Waste Cover Systems MEADOWBANK GOLD PROJECT

67 2006  Currently proposed 2 m thickness of UM progressively placed over tailings facility –Based on site thermistor data –Single layer system –Consideration of alternative cover design strategies during detailed engineering design  Adaptive management strategy –Install thermistors and monitoring wells to evaluate predictions against actual performance –Develop test pads to evaluate different cover design strategies –Adjust closure designs accordingly Project Alternatives Mine Waste Cover Systems for Cold Regions MEADOWBANK GOLD PROJECT

68 2006 Project Alternatives Dewatering Dikes MEADOWBANK GOLD PROJECT

69 2006  Design Considerations – Allowable seepage – Foundation conditions – Construction materials availability – Geometry/constructability – Cost  Cutoff alternatives considered – Low permeability upstream blanket – Central low permeability core – Slurry trench cut-off wall – Interlocking vinyl sheet piles Project Alternatives – Dewatering Dikes Construction Alternatives MEADOWBANK GOLD PROJECT

70 2006  Double rockfill berms with till core and slurry cut-off wall; – Construction materials direct from mine development  Construct rockfill berms and till core  Excavate soil-bentonite cut-off wall  Standard Caterpillar 320 up to 6 m depth.  Standard Long Reach Caterpillar 320BL up to 12 m depth.  Custom Long Reach Excavator or Stick/Boom up to 30 m depth. Project Alternatives – Dewatering Dikes Selected Section MEADOWBANK GOLD PROJECT

71 2006  Proposed Dike Construction is within current engineering precedent for this type of structure –Examples of use of till in dike construction in water: Keenlyside Dam, St. Lawrence Seaway till cofferdam, Three Gorges Dam cofferdam in China (up to 60 m water depth)  Dike Construction is sequenced: East Dike (2-4 m water), Bay Zone Dike (up to 8 m water) and Goose Island Dike (up to 18 m) with some sections in deep water  Access to range of till and rock material at start of pit developments  Construction contingencies Project Alternatives – Dewatering Dikes Proposed Construction MEADOWBANK GOLD PROJECT

72 2006  Bauer Cutter Soil Mixers (CSM)  Clam Excavation –120 tonne crane/clam  Trench remixing (TRD) Project Alternatives – Dewatering Dikes Construction Contingencies for Cut-off Wall MEADOWBANK GOLD PROJECT

73 2006 Project Alternatives Pit and Dike Risk Evaluation MEADOWBANK GOLD PROJECT

74 2006 Failure Mode ConsequenceMonitoring/Action Overtopping Water spill into pitDike Freeboard, Lake outflow channels inspected Internal Erosion Till core progressive erosion by void or defect in construct with minor to major toe seepage Regular walk-over inspections Remedial action reverse filter and rockfill buttress Seepage within Foundation Failure by pore pressure induced instability.Observed during initial dewatering or very shortly thereafter. Heightened inspection frequency during dewatering and first year Piezometer monitoring, expected to draw down phreatic surface as open pit deepens Slope Instability Foundation failure would cause a rotational slip in the wide rockfill shell Earthquake loading for this site is a low, limited dike displacements expected Mechanism in foundation soils expected to develop slowly Monitor for settlement and cracks in the dike crest. Walk-over inspection. Unexpected Settlements Could lead to water flowing over rockfill shells.Freeboard and No enhanced monitoring required, as excessive settlement would be apparent from the seepage. Pit Slope Failure Involving Pt slope and Dike Localized to Pit Slope Minimum set back distance for Dike toe to Pit wall Localized pit stability monitored by prisms during mining operations. Potential Risks, Mitigation, and Monitoring Pits and Dikes MEADOWBANK GOLD PROJECT

75 2006 Potential Risks, Mitigation, and Monitoring Pits and Dikes – Goose Island Section MEADOWBANK GOLD PROJECT

76 2006 Project Alternatives Other Project Dikes MEADOWBANK GOLD PROJECT

77 2006  Single rockfill berm with till core  Very shallow water Project Alternatves – Dewatering Dikes Vault Dike MEADOWBANK GOLD PROJECT

78 2006  Single rockfill dike with compacted till core  Constructed in dry conditions Project Alternatves Stormwater Dike and Perimeter Dikes MEADOWBANK GOLD PROJECT

79 2006 Project Alternatives Other Issues MEADOWBANK GOLD PROJECT

80 2006  Disposal to pits – Cleaned and stripped of potential pollutants  Disposal in landfill area – Decontaminated items that could not be cleaned sufficiently for disposal in pits  Disposal off-site/returned to supplier – Chemicals, batteries, insulation  Develop Operations/Maintenance Manual for operation of landfill site Disposal of Non-Salvageable Items MEADOWBANK GOLD PROJECT

81 2006 Water Quality Water Quality Predictions MEADOWBANK GOLD PROJECT

82 2006 Use best available site-specific data, experience elsewhere, conservative assumptions  Site specific data: –Waste rock/tailings leaching rates: –baseline water quality (surface and groundwater) –Temperature profiles for soil, air –Planned waste, water management  Experience elsewhere – arctic conditions: –Explosives: ammonia, nitrate at Diavik, Ekati –Temperature, active layer: Cullaton Lake, Ekati, Nanisivik, North Rankin Inlet, Raglan Water Quality - Predictions Basis of Assessment

83 2006 Water Quality - Predictions  Conservative assumptions: –Tailings frost free and 0.65m unsaturated throughout operation – immediate ARD –Rock ARD: Proportion of PAG rock (uncertain=PAG), IF-ARD starts immediately, all metals released (no retention) –Rock pile field capacity attained at closure (all infiltration drains) –Rock pile Active layer of 8 meters –No progressive reclamation (no cover until end of mine life) –Water ponds: no degradation of N-species (ammonia, nitrate, CN by-products) Basis of Assessment

84 2006 Water Quality - Predictions  Adapt Laboratory data to site conditions – scaling factors: –Climate: colder, dryer, temperature air=rock –Active thaw layer, freezing of core controls ARD, –Composition of waste: better representation from large samples (100-kg bulk samples) –Vault rock pile not acid-generating –Rock waste (pit, rock pile): coarser, smaller surface area per mass –Hydrology (rock piles, open pits): runoff vs infiltration, channelling –Submerged rock minimal ARD –Calculated effect of heat of oxidation reaction – minor (tailings, worst case <0.5 o C /m 3 /d) –Unionized ammonia: low due to neutral-low pH, low temperature Basis of Assessment

85 2006 Water Quality - Predictions  Best estimate: –Field cells leaching rates –Factored leaching rates: particle size only –2-meter active layer, freezing of core rock pile, tailings –Explosive wastage 3%  Possible Poor-end – Evaluation of impacts, treatment requirements –Laboratory leaching rates, 100-kg bulk samples, –Factored leaching rates: temperature, particle size, rock wetting –8-meter active layer, freezing of core rock pile, tailings –Explosive wastage 5% Possible Range of results

86 2006 Predicted Water Quality Portage, Goose, Vault Expected CasePossible Poor-End Rock piles, open pitsMeet MMERRequires treatment Attenuation ponds (early discharge) Meet MMER, toxicity, no treatment Requires in-situ treatment Tailing Reclaim Pond (year 9 discharge) Not discharged, treated at end of mine life Portages and Wally Lakes Meet drinking water standards and aquatic life guidelines Meet drinking water standards, no effects to biota

87 2006 Predictions - Vault Area Expected CasePossible Poor-end > MMER> CCME> MMER> CCME Rock Pile drainage n.e.un-ionized NH3n.e.As, un-ionized NH3 Open Pit drainage n.e.un-ionized NH3n.e.As, un-ionized NH3 Attenuation Pond n.e.Al, Cd, Cu, F, Hgn.e.As, Cd, Cu, F, Hg Year-23 Vault Pit Lake n.e.Cr, Cd*n.e.As, Cd*

88 2006 Prediction - Portage Area Expected CasePossible Poor-End > MMER> CEQG> MMER> CEQG Rock pile drainagen.e.unionized NH 3 pH pH, Al, As, Cd, Cr, Cu, Fe, Hg, Ni, Pb, Se, Zn North Portage Pitn.e.pH, Al, Cd, Fn.e.pH, Al, As, Cd, F, Fe Third Portage Pitn.e.pH, Al, Cd, F, Fen.e.pH, Al, As, Cd, F, Fe, Zn Goose Island Pitn.e.pH, Cdn.e.pH, As, unionized NH 3 Attenuation pond (years 1 to 4)n.e. pH, Al, Cd, F, unionized NH 3 n.e.pH, Al, As, Cd, Cu, F Tailing Reclaim Pond (years 5 to 9) Total CN, Cu Ag, As, Cd, Cr, Cu, F, Hg, Mo, Se, Tl, Zn As, Cu, Ni, Zn Ag, As, Cd, Cu, Cr, F, Hg, Mo, Ni, Pb, Se, Tl, Zn

89 2006 Water Treatment  Tailings process water: –INCO SO 2 -air cyanide destruction process –Less toxic SCN, CNO by-products –In-pond processes may increase ammonia, lower pH  Reclaim pond effluent - active treatment: –Closed-loop, water not discharged until end of mine life –Ore process plant transformed into water treatment plant at end of mine life –Proposed: HDS (metals), ferric sulphate (As), lime, CO 2 (pH control) –Test work during operation – efficiency, final design Tailing water

90 2006 Water Treatment  Attenuation pond effluent, pit lakes – if required: –In-situ enhanced bio-attenuation: nutrient (P), pH - metal control (lime, sodium hydroxide) Adequate retention time, holding capacity –Biomass uptake of nutrients, no net addition to water quality –Monitoring and test work during operation: source control, additive dosages, efficiency In-pond treatment

91 2006 Prediction - Portage Pit Lakes Expected CasePossible Poor-End > MMER> CEQG> MMER> CEQG Rock Storage Arean.e. AsAs, Cd, Cr, Cu, Hg, Se Goose Pit Laken.e.As, Cdn.e.As, Cd Portage Pit Laken.e.Cd, Znn.e.Cd, Zn

92 2006 Effluent Mixing in Lakes  All maxima less than D.W. and CCME aq. life except:  Manganese >DW aesthetic: –conservative predicted loadings from dike leaching  Cadmium >CCME aq. Life, max increase of 5% -baseline below analytical detection -conservative prediction use artificial Cd concentration (half detection limit) Third Portage Lake

93 2006 Effluent Mixing in Lakes  Maximum modelled concentrations all < DW except:  Cd CCME aq.life, increase by max 2% (0.001 ug/L) ** baseline conditions > CCME aq.life because low hardness Second Portage Lake

94 2006 Effluent Mixing in Lakes  Maximum modelled concentrations < D.W. and aq. life except arsenic, cadmium CCME aq.life  Maximum arsenic to increase to 6 ug/L –1 ug/L above CCME aq. Life near end of operations  Cadmium predicted to increase by 0.02 ug/L – baseline > CCME aq.life because of low hardness Wally Lake (Vault area)


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