Geochemistry and Water Quality Volume III: Seepage and Water Quality for Recliamed Tailings Containment Area – Lupin Operation Presentation to; The Nunavut Water Board April 11, 2006 Presented by; Ron Nicholson, PhD. Ecometrix Incorporated

Objectives Verify that the Closure Plan is based on sound geochemical principals Verify that downstream water quality is protected for ongoing permafrost conditions Assess water quality for future conditions if thawing of permafrost occurs

Scope Review of existing water quality data –Porewater in cover above tailings –Surface water ponds and discharge Geochemical calculations to predict quality of tailings porewater Diffusion modelling to estimate oxidation rates and water quality in unfrozen tailings

Lupin Tailings Containment Area

Locations of Shallow Pipes to Collect Porewater in Cover above Tailings Cell 1 WC- WC- 4 WC- WC- 5 WC- WC- 6 WC- 3 Cell 1ACell 2

Selection of Constituents of Potential Concern (COPC)

Porewater: Trends in pH

Porewater: Trends in Arsenic

Porewater: Trends in Nickel

Porewater: Trends in Copper

Surface Water Sampling Locations

Surface Water: Trends in pH

Surface Water: Trends in Arsenic

Surface Water: Trends in Nickel

Surface Water: Trends in Copper

Comparisons Between Porewater and Surface Water Quality

Sulphate/Metal Ratios and Scaling Factors in Oxidation Column Test

Sulphate/Metal Ratios and Scaling Factors in Porewater Above Tailings

Predicted Porewater Concentrations Below the Water Table for Lab and Porewater Scaling Factors FeS /4 O 2  2SO Fe(OH) 3 + 4H +

Post Permafrost – Some Tailings May Partially Desaturate Near the Dams Oxidizing Tailings Dam Unoxidized Tailings Infiltration Oxygen Water Infiltration FeS 2 + O 2 ==> Fe 2+ / SO 4 2- / H + Evaporation Years to Decades Years Esker CoverRunoff

Diffusion Coefficient as a Function of Saturation of Pore Spaces by Water in Tailings

Predicted Sulphate Concentrations in Porewater for a Range of Saturation Values

Dilution Factors for Porewater Seepage into Basin Discharge for the Seepage Cases Assessed

Predicted Concentrations in Basin Discharge for Min and Max Dilutions Using the Porewater Scaling Factors

Predicted Concentrations in Basin Discharge for Min and Max Dilutions Using the Column Test Scaling Factors

Conclusions Lupin tailings are potentially acid generating if exposed to atmosphere for prolonged periods Quality of existing porewater in the esker cover above the tailings has been influenced by historic oxidation before cover construction Development of a shallow water table in the esker cover is protective of downstream water quality for ongoing permafrost conditions

Conclusions If permafrost thaws, the Lupin Tailings will retain high degrees of moisture below the cover and will only partially desaturate near the dams The high saturation will limit the diffusion of oxygen and oxidation rates in the desaturated tailings Predicted concentrations of COPCs in the basin discharge are near or below guideline values when reasonable scale-up factors for sulphate to metal ratios are applied Estimated concentrations for low dilutions and higher scale-up factors are less than current criteria in the basin discharge Overall, the closure plan is considered to be protective of downstream water quality