The Water - Part I Mine Water Quality and Site

Water ManagementPresented by: Kelly Sexsmith Peter McCreath SRK Consulting Clearwater 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 pH’s and low concentrations of soluble trace metals

– Development Pile Seep Samples• Neutral pH’s• 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 pH’s • 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

NH4mg/L

Average          

Waste Rock and Overburden 0.59 0.00061 0.064 0.020 0.28 2.9

PK Supernatent 0.45 0.00016 0.0029 0.036 0.00014 0.08

Kimberlite Ore and LGO Stockpiles 0.25 0.0033 0.0031 0.18 0.0165 1.5

Coarse Kimberlite Stockpile 0.25 0.0042 0.0031 0.17 0.080 3.3

Upper Bound          

Waste Rock and Overburden 0.87 0.00061 0.064 0.041 2.3 5.8

PK Supernatent 2.8 0.0005 0.0066 0.16 0.00056 0.17

Kimberlite Ore and LGO Stockpiles 0.25 0.0041 0.0045 0.18 0.03 2.9

Coarse Kimberlite Stockpile 0.25 0.0072 0.0045 0.18 0.16 6.6

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 PondLake C3

Carat Lake

Open Pit and Underground

Mine

Waste Dump#2

Waste Dump#1

Overburden Stockpile

Processing Plant

Pond A

Pond B

Pond C

PitPond

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 m3

• 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 m3

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

NH4mg/L

Average 0.51 0.0008 0.020  0.037 0.13 1.8

Upper Bound 1.0 0.0010 0.021 0.070 0.68 2.9

  Al mg/L

Cd mg/L

Cu mg/L

Ni mg/L

U mg/L

NH4mg/L

Average 0.66 0.001 0.027 0.050 0.18 2.2

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