The Water - Part I Mine Water Quality and Site Water Management Presented by: Kelly SexsmithPeter McCreath SRK ConsultingClearwater Consultants

Presentation Overview Part I – Mine Water Quality and Management –Water Quality Issues –Characterization of Mine Rock and PK –Concentration Estimates from Mine Rock and PK –Site Water Management –Water and Load Balance –Discharge Concentrations –Monitoring Part II – Receiving Water Quality Part III – Water Treatment

Key Water Quality Issues Nutrients –Waste Stockpiles and PKCA –Sewage Suspended Solids –Waste Stockpiles and PKCA –Other Construction Areas Acid Rock Drainage and Metal Leaching Potential –Waste Rock Piles –Coarse Processed Kimberlite Stockpiles –Low Grade Kimberlite Stockpiles –Fine Processed Kimberlite

Geology Overview

Geochemical Tests Acid Base Accounting Mineralogy Metal Analyses Leach Extraction Tests Process Water Quality Settling Tests Water Quality of Seeps from Development Pile

Test Results Granitic Rocks –ABA Low sulphur concentrations and low neutralization potential Low potential for acid generation –Extraction Tests Neutral pHs and low concentrations of soluble trace metals –Development Pile Seep Samples Neutral pHs Somewhat elevated aluminum, copper, and uranium concentrations Low concentrations of other metals

Test Results Kimberlite Ore and Low Grade Ore –ABA Low sulphur concentrations and very high neutralization potential –Leach Extraction Tests Slightly alkaline pHs Slightly elevated cadmium molybdenum and nickel Low concentrations of other soluble trace metals Coarse and Fine PK –All tests similar to the ore

Source Concentration Estimates Approach –Metals Scaling-up from short-term laboratory results Reality Checks using data from other similar sites –Nutrients Ferguson and Leask Model Comparisons with other sites Existing data from site not representative because open pit mines generate less residues What the Estimates Represent –Conditions at the base of the piles –Short-term water quality (i.e. highest concentrations)

Source Concentrations Al mg/L Cd mg/L Cu mg/L Ni mg/L U mg/L NH4 mg/L Average Waste Rock and Overburden PK Supernatent Kimberlite Ore and LGO Stockpiles Coarse Kimberlite Stockpile Upper Bound Waste Rock and Overburden PK Supernatent Kimberlite Ore and LGO Stockpiles Coarse Kimberlite Stockpile

Layout of Water Management Facilities

Supplementary Information Key changes made in response to FEIS comments: increased security and flexibility with water management, i.e. may discharge directly or pump to PKCA prior to discharge or treat prior to discharge elimination of several small collection ponds due to footprint adjustments at dumps/stockpiles (1 catchment) addition of ditch C4 to reduce the catchment at Pond A addition of 2 collections ponds ( B and C) addition of several sumps/pumps at the plant site spillways added at PKCA and settling (polishing) pond contingency related to water quality (discussed by others)

PKCA Area (Water Storage) Settling Pond Lake C3 Carat Lake Open Pit and Underground Mine Waste Dump#2 Waste Dump#1 Overburden Stockpile Processing Plant Pond A Pond B Pond C Pit Pond Spray Irrigation Ore Stockpile Coarse PK Stockpile Low Grade Stockpile Water Management Flow Diagram

Water Management Plan Water from waste dumps and stockpiles to be collected in 3 ponds (A, B and C); depending on water quality, pond water reports to either PKCA or environment Water from plant site to be collected in a series of sumps and/or Pond C; depending on water quality, pond water reports to either PKCA or environment Depending on water quality, water at PKCA is either directed to settling pond and discharged, or pumped to spray irrigation area (land application) Flocculants to be added at PKCA or settling pond, as necessary Contingency related to water quality discussed elsewhere

Water Management Design Criteria Diversion Channels – 200 year peak instantaneous flow plus freeboard allowance Collection/Sediment Ponds A, B & C – combination of storage plus pumping for 200 year maximum snowmelt month plus sediment settling In-pit sump – 10 to 25 year event PKCA and Settling Pond spillways – Probable Maximum Precipitation inflow event

Water Balance – Base Case 8 years of ore processing average precipitation and evaporation conditions all water, runoff and seepage from all site components directed to PKCA no water reclaimed from PKCA to plant ice entrainment is extensive maximum pond level in the PKCA is el. 523 (spillway level) minimum allowable pond volume is 100,000 m 3 no release from PKCA for first 2 years of operation releases from PKCA commence in 3rd year (over June- Sept period, adjust rate for maximum dilution) maximum annual release is assumed to be 1,000,000 m 3

PKCA Storage Volume Variation – Base Case

PKCA & Settling Pond Elevation Variation – Base Case

Discharge Concentrations Over Time

Discharge Concentrations Operations (Discharge from PKCA) Post Closure (Pit Water Quality) Al mg/L Cd mg/L Cu mg/L Ni mg/L U mg/L NH4 mg/L Average Upper Bound Al mg/L Cd mg/L Cu mg/L Ni mg/L U mg/L NH4 mg/L Average

Mine Site Monitoring Stations PKCA Inputs –Collection Ponds A, B and C –Pit Sump –PK Supernatant (Process Water) –Recovery Plant Rejects Drainage –Treated Sewage PKCA Discharges