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Cumberland Resources Ltd.

Cumberland Resources Ltd. MEADOWBANK GOLD PROJECT. 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

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Cumberland Resources Ltd.

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  1. Cumberland Resources Ltd. MEADOWBANK GOLD PROJECT 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. MEADOWBANK GOLD PROJECT Overview of Baseline Studies Thermal Regime and Permafrost

  3. MEADOWBANK GOLD PROJECT Thermal Regime and Permafrost Key Considerations for Cold Regions • 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

  4. MEADOWBANK GOLD PROJECT Thermal Regime and Permafrost Permafrost Map of Canada

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

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

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

  8. MEADOWBANK GOLD PROJECT Thermal Regime and Permafrost Summary of Permafrost Regime • 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 -11.3 to -11.8 oC

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

  10. MEADOWBANK GOLD PROJECT Overview of Baseline Studies Geochemistry

  11. Meadowbank Geology Goose Island Deposit

  12. Meadowbank Geology Vault Deposit

  13. Baseline Geochemical Sampling

  14. IV IF UM Pit Rock Core

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

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

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

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

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

  20. Vault Portage Trench Water Sampling

  21. Rock Geology, Mineralogy *Neutralisation potential (NP) in kg calcium carbonate equivalent per tonne of rock

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

  23. 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 (<<MMER, >CCME) • Overland runoff: • Low metals, low pH (organic acids)

  24. MEADOWBANK GOLD PROJECT Overview of Baseline Studies Groundwater Quality and Quantity

  25. MEADOWBANK GOLD PROJECT Groundwater Studies Groundwater Quality

  26. Groundwater Quality Baseline StudiesEstimation of Thaw Bulb Location • 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

  27. 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 10-8 m/s MEADOWBANK GOLD PROJECT Groundwater Studies Hydraulic Conductivity

  28. Characterized by falling head tests in till units Estimated 1 x 10-7 to 3 x 10-4 m/s Consistent with laboratory testing K=2 x 10-6 to 4 x 10-5 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 MEADOWBANK GOLD PROJECT Groundwater Studies Shallow Groundwater Flow Regime

  29. MEADOWBANK GOLD PROJECT Groundwater Studies Existing Thermal/Hydrogeologic Regime Based on Site Data

  30. MEADOWBANK GOLD PROJECT Groundwater Studies Deep Groundwater Regime Open Pits • 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 Dikes K zones Permafrost

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

  32. MEADOWBANK GOLD PROJECT Groundwater Studies Groundwater Salinity/Freezing Point Depression • 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.

  33. 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 Open Pits Dikes K zones Permafrost MEADOWBANK GOLD PROJECT Groundwater Inflows to pits Total Average Inflow

  34. MEADOWBANK GOLD PROJECT Project Alternatives Project Alternatives

  35. MEADOWBANK GOLD PROJECT Project Alternatives – Access Road Land Route Alternatives • 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

  36. MEADOWBANK GOLD PROJECT Project Alternatives – Access Road Permanent AWR Alternatives • 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

  37. MEADOWBANK GOLD PROJECT Project Alternatives – Access Road Permanent AWR Alternatives • 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

  38. MEADOWBANK GOLD PROJECT Project Alternatives – Access Road Permanent AWR Alternatives • 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

  39. MEADOWBANK GOLD PROJECT Project Alternatives Waste Management Systems for Cold Regions

  40. MEADOWBANK GOLD PROJECT Project Alternatives – Waste Management Key Environmental Issues or Aspects to be Addressed 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

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

  42. MEADOWBANK GOLD PROJECT Project Alternatives – Rock Storage Portage Area Rock Storage Options • 4 options evaluated for Portage Deposit Area

  43. MEADOWBANK GOLD PROJECT Project Alternatives – Rock Storage Vault Area 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

  44. MEADOWBANK GOLD PROJECT Project Alternatives – Rock Storage Management Strategy • 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

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

  46. MEADOWBANK GOLD PROJECT Project Alternatives – Tailings Storage Initial Evaluation • 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 Influence of Factors on Weighted Total

  47. MEADOWBANK GOLD PROJECT Project Alternatives – Tailings Storage Summary of Additional Sensitivity Evaluations • To evaluate the influence of relative weighting factors • All weighting factors set to 1 to remove bias imposed by personal preference • To weight heavily to environmental factors • Excluded economic factors completely • Decreased influence of operational factors • 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 • 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

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

  49. MEADOWBANK GOLD PROJECT Project Alternatives – Tailings Storage Advantages of Selected Site C • 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

  50. MEADOWBANK GOLD PROJECT Project Alternatives Tailings Management

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