DE BEERS GAHCHO KU PROJECT ICRP TECHNICAL WORKSHOP Yellowknife, NT - - PowerPoint PPT Presentation

DE BEERS GAHCHO KUÉ PROJECT ICRP TECHNICAL WORKSHOP

Yellowknife, NT October 7, 2016

1 The De Beers Group of Companies

CONTENTS OF THE INTERIM CLOSURE AND RECLAMATION PLAN

• 1. Executive summary
• 2. Introduction
• 3. Project environment
• 4. Project description
• 5. Permanent closure and reclamation
• 6. Progressive reclamation
• 7. Temporary closure
• 8. Integrated schedule of activities approaching permanent closure
• 9. Post-closure site assessment

10.Financial security Appendices

• A. Glossary of Terms and Definitions
• B. List of Acronyms, Abbreviations, Units, and Symbols
• C. Record of Engagement
• D. Supporting Documents
• E. Reclamation Research Plan

2 The De Beers Group of Companies

Gahcho Kué ICRP Section 5: Permanent Closure and Reclamation Section 6: Progressive Reclamation

3 The De Beers Group of Companies

For closure planning, the mine is separated into the following 5 mine areas:

• Open Pits
• Mine Rock Piles
• PK Disposal Areas
• Infrastructure
• Kennady Lake

Progressive reclamation is built into the mine plan

PROJECT DESCRIPTION

4 The De Beers Group of Companies

• 1. OPEN PITS

5034

• 300m deep
• partially back-filled with mine rock and coarse PK

~2m-50m m to the surface Hear arne e

• 250m deep
• partially back-filled with mine rock, fine PK and

coarse PK ~50 m to the surface Tuzo

• 360m deep
• filled with water from the water management pond
• chemocline will form between the water

management pond water and the freshwater cap

5 The De Beers Group of Companies

1. OPEN PITS - POST CLOSURE VISION OP1: allow for the establishment of sustainable aquatic ecosystem; OP2: physically stable 300 m 250 m 360 m ~50 m ~140 m Waste Rock & PK Waste Rock & PK Dense Water 5034 Pit Hearne Pit Tuzo Pit > 2.0 m ~> 50 m

420.7 masl

6 The De Beers Group of Companies

Coarse PK (0.25 mm to 6.5 mm particle size) Non-PAG

• Trucked to CPK pile
• 23.4 MT produced during life of mine
• 2016-2021:

Coarse PK Pile (~43%)

• 2022-2027:

Hearne/5034 (~47%),

• 2022

CPK Progressive reclamation starts Fine PK (<0.25 mm particle size) Non-PAG

• Pumped as thickened slurry
• 10 MT produced during life of mine
• 2016-2020:

Fine PKC Containment Facility (~37%)

• 2021-2027:

Hearne Pit (~63%)

• 2021:

FPK Progressive Reclamation starts

• 2. PROCESSED KIMBERLITE DISPOSAL AREAS

Fine Processed Kimberlite Facility Coarse Processed Kimberlite Facility

7 The De Beers Group of Companies

• 2. FINE PK FACILITY – POST CLOSURE VISION

PK1: prevent PK from entering surrounding environment PK2: physical stable

• Height – variable, ~15 m high
• ~2% Slope during operations
• Filter dyke to contain solids, spillway to be

installed at closure

• Covered with a layer of coarse PK (1m)

and mine rock (1.5m)

• Permafrost will aggrade within the interior

(not required)

~15 m Fine PK 50 1 ~1 m cap

PK spigot location to be adjusted throughout operations

8 The De Beers Group of Companies

Coarse PK Pile

• Approximately 35 m high
• Material will be graded to 4W:1H and include a mine rock

cover (1m)

• Permafrost will aggrade within the interior (not required)
• 2. COARSE PK FACILITY– POST CLOSURE VISION

PK1: prevent PK from entering surrounding environment PK2: physical stable

~35 m Coarse PK 4 1

9 The De Beers Group of Companies

• 300 MT of waste rock will be generated (7.5%/22.5MT PAG)
• Landfill waste and contaminated rock
• >31 m from OHWM
• >50m from edge of pile
• Capped with till, mine rock
• PAG rock in waste rock piles
• >15m from edge
• Overlain by 2m of till/overburden
• Below OHWM of Kennady Lake (420.7masl)
• Above OHWM of Kennady Lake (421.5masl)
• On 2m mine rock if not submerged
• 3. MINE ROCK PILES – SOUTH AND WEST MINE ROCK PILES

South Mine Rock Pile

10 The De Beers Group of Companies

• 3. WASTE ROCK PILE – ROCK PLACEMENT

PAG >15 m 2 m Till 2.2 to 2.4 1 PAG

420.7 masl

11 The De Beers Group of Companies

• ~100 MT of waste rock/pile
• Top of pile elevation - ~550 masl
• Original ground surface – variable ~430 masl
• Overall height - ~120 m
• Bench – 15 m height, 15 m width, 1.3:1V slope
• Overall slope – 2.2H:1V to 2.4H:1V
• Permafrost will aggrade within the interior (not

required)

• No cover or revegetation (commitment to further

discuss with Aboriginal communities)

• 3. MINE ROCK PILES – POST CLOSURE VISION

MR1: stable slopes to limit risks to wildlife and people MR2: waste disposal areas are safe

12 The De Beers Group of Companies

All other structures constructed to support the Project. Notable components include:

• Roads and the Airstrip
• Power Plant and fuel storage
• Accommodations complex
• Processing Facility
• Maintenance shops
• Laydowns and warehouses
• AN Storage Facility
• Landfarm
• 4. INFRASTRUCTURE

13 The De Beers Group of Companies

• Buildings inspected and hazardous materials

removed for off-site disposal

• Salvageable equipment and materials will shipped
• ff-site
• Inert solid materials will be placed in the landfill

areas within the Mine Rock Piles or the mined out Tuzo Pit

• Soil contamination assessed, excavated and

shipped off-site as needed

• Final grading plan will be developed to restore

natural drainage where possible

• Scarifying and contouring of compacted surface

soils (e.g. roads and airstrip) to encourage the natural revegetation process

• 4. INFRASTRUCTURE – POST CLOSURE VISION

I1: Disturbed areas will be safe for people, wildlife, and vegetation

14 The De Beers Group of Companies

• Dyke A constructed
• Southern basin = de-watered
• 18.63 Mm3 of water to pumped

to A8 and N11

• Dykes used to control water
• Fine PK facility constructed
• Water monitored as per the SNP
• Downstream monitored as per

the AEMP

• 5. KENNADY LAKE – CONSTRUCTION

15 The De Beers Group of Companies

• Northern basin = Water

Management Pond

• Fine PK added to Fine PK facility
• Active mining of 3 pits
• Mine Rock Piles are active
• Dykes are constructed
• Collection Ponds constructed
• Annual discharge if water meets

the EQC’s

• Downstream flow mitigation to A8
• 5. KENNADY LAKE – OPERATIONS

16 The De Beers Group of Companies

• Internal dykes lowered (B,J,N) to ~417

masl

• Water Management Pond drains to Tuzo
• Fish habitat enhancements created
• External dykes breached (E,F, and G) to

re-connect with upstream waterbodies.

• Supplemental water pumped from N11

to Kennady Lake

• Breach dyke K to connect with A7
• Breach dyke A – reconnect with the

downstream

• 5. KENNADY LAKE – ACTIVE CLOSURE AND REFILLING

17 The De Beers Group of Companies

Water Management Pond water will be at the bottom of Tuzo pit Chemocline will have formed Internal dykes will have been breached, enhanced or left in place so long as they do not pose a risk to navigation of small craft Lake level will be 420.7 masl = the same as baseline Water will be safe to drink and the fish will be good to eat

• 5. KENNADY LAKE – POST CLOSURE VISION

KL1: functioning aquatic ecosystem KL2: stable banks KL3: small craft navigation

18 The De Beers Group of Companies

Fisheries Authorization (paraphrased) 4.1 Fish Habitat shall be re-established through re-filling of Kennady Lake, breaching of dykes, allowing fish to migrate back into the lake 4.2 Fish habitat features shall be constructed within the re-established Kennady Lake including finger dykes, artificial reefs, and littoral habitat near the pits 5.1.5 The use of the fish habitat features constructed within the lake shall be evaluated by demonstrating fish presence on the features at appropriate life stages as per the Fish Habitat Validation Plan submitted prior to final construction of the features 5.1.6 Once Kennady Lake is refilled, confirmation is required that each species

• f fish that occurred in Kennady Lake at baseline, are occupying the expected

habitat types within Kennady Lake and that the habitat within the lake has the features required for those fish. The Fish Habitat Validation Plan will define the monitoring objectives

• 5. KENNADY LAKE – Re-establishment of Aquatic Ecosystem

19 The De Beers Group of Companies

(AANDC et al, 2013)

20 The De Beers Group of Companies

OBJECTIVES

SW1 – Air quality levels safe for people, vegetation, aquatic life and wildlife. SW2 – Drainage pathways for surface runoff are physically stable. SW3 – Surface runoff and seepage water quality that is safe for people, vegetation, aquatic life, and wildlife. SW4 – Mine areas are physically stable for use by people and wildlife. SW5 – Promote accelerated natural recovery of vegetation at disturbed areas SW6 – Safe passage and use for Caribou and other wildlife. SW7 – Aesthetic conditions of the Mine area are similar to surrounding natural conditions OP1 – Backfilled and/or flooded pits will not adversely impact establishment of sustainable aquatic ecosystems and life in the overlying Kennady Lake and downstream waterbodies. OP2 – Physically stable pit walls to limit risk of a failure impacting people and aquatic life. KL1 – Return Kennady lake to a state that will support a functioning aquatic ecosystem and traditional uses KL2 – Physically stable constructed banks of Kennady Lake to limit risk of failure that would impact aquatic life, wildlife and people. KL3 – Small craft navigation through dyke and pit area. MR1 – Physically stable slopes to limit risk of failure that would impact the people or wildlife. MR2 – Contaminated soils and non-hazardous waste disposal areas within piles do not pose an unacceptable risk to aquatic life, people or wildlife. PK1 – Prevent PK from entering the surrounding terrestrial and aquatic environment. PK2 – Physically stable PK disposal areas to limit risk of facility failure. I1 – Disturbed areas will be safe for people, wildlife, and vegetation.

21 The De Beers Group of Companies

Reviewers have commented that the ICRP should define ‘safe’ Merriam-Webster Dictionary defines safe as: Simple definition

: not able or likely to be hurt or harmed in any way : not in danger : not able or likely to be lost, taken away, or given away : not involving or likely to involve danger, harm, or loss

What do we mean by ‘safe’?

Full definition:

1: free from harm or risk : unhurt 2a :secure from threat of danger, harm, or loss 2b :successful at getting to a base in baseball without being put out 3: affording safety or security from danger, risk, or difficulty 4: obsolete of mental or moral faculties : healthy, sound 5a :not threatening danger : harmless b :unlikely to produce controversy or contradiction 6a :not likely to take risks : cautious b trustworthy, reliable

22 The De Beers Group of Companies

Suggested definition of safe in the ICRP: 1) Safe = not to likely to cause harm or injury 2) Harm = physical damage or injury : something that causes someone or something to be hurt, broken, made less valuable or successful 3) Injury = harm or damage : an act or event that causes someone or something to no longer be fully healthy or in good condition

What do we mean by ‘safe’?

23 The De Beers Group of Companies

Table 20: Closure objectives, criteria, method of measurements to evaluate achievement of criteria, and planned reclamation research

Proposed Objective Proposed Criteria Primary Reclamation Activities Post-closure inspections and/or Monitoring Reclamation Research SW1 – Air quality levels safe for people, vegetation, aquatic life and wildlife. Closure air quality criteria will be developed using territorial/federal guidelines or site-specific risk-based criteria. Engineering design and construction of a cover placed over the fine PK deposited within the Fine PK Facility. Cessation of mining and construction activities (e.g. diesel combustion, surface vehicle traffic, blasting, material crushing and handling, etc.) will play a large role in diminished air emissions. Air quality monitoring for suspended particulates will be completed post- closure during the summer for 3 years post closure. Geotechnical monitoring

• f the constructed rock

cover will occur to ensure long-term performance as a barrier. See Closure Objective PK1&2 for more detail regarding monitoring activities. None.

24 The De Beers Group of Companies

Gahcho Kué Section 7: Integrated Schedule of Activities

25 The De Beers Group of Companies

TIMELINE FOR CLOSURE

Opera ration ions Closu

• sure and

d Reclamation ion

Operations Post-Closure Closure

ACTIV IVIT ITY Y / Y YEAR 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 2043 2044 Mine e Year 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 5034 Pit Hearne Pit Tuzo Pit Fine PK Facility Coarse PK Pile South Mine Rock Pile West Mine Rock Pile Infrastructure Refilling Kennady Lake Reclamation Performance Monitoring Opera ration ion Closu

• sure

e and d Reclamation ion

26 The De Beers Group of Companies

Gahcho Kué Appendix E: Reclamation Research

27 The De Beers Group of Companies

• Research will be completed on:
• Topics where stakeholders have expressed concern and De

Beers committed to further study

• To support improvements on executing the closure activity
• r detailed design
• Planned research identified in the ICRP:
• Revegetation
• Post closure seepage quality and quantity from the waste

rock and PK facilities

• Final landform options to support wildlife
• Physical stability of engineered rock covers
• Stability of chemocline within flooded pits
• Timeline for reconnection of Kennady Lake to surrounding

waterbodies

RECLAMATION RESEARCH

28 The De Beers Group of Companies

Un Uncer ertaint tainty: : Assess the most effective methods to facilitate the re-establishment of native vegetation on the roads, pads and other infrastructure areas at the Mine

• site. Assess achievable growth rates and timelines on

the disturbed areas.

• Best Management Practices and Case Studies Review

– focus on recent, successful examples

• Upland and Riparian Revegetation Research – field

test plots

• Aquatic Revegetation Research – in concert with DFO
• Overburden and Lake Sediment Stockpile Volume

Balance and Management – use of this material to support revegetation

RECLAMATION RESEARCH - REVEGETATION

29 The De Beers Group of Companies

Un Uncer ertaint tainty: : Quality and quantity of seepage at major mine waste areas (i.e. Coarse PK Pile, Fine PKC Facility, and Mine Rock Piles) in post closure.

• Data collection – runoff seepage monitoring as per

the Project Water Licence.

• Comparison of predicted and measured seepage

data – potential implications to the closure design assessed

RECLAMATION RESEARCH – POST CLOSURE SEEPAGE QUALITY AND QUANTITY

30 The De Beers Group of Companies

Un Uncer ertaint tainty: : Closure options that would provide potential benefit for caribou and other local wildlife.

• Desktop review of best practices and case studies –

successful implementation of wildlife habitat features at comparable reclaimed industrial sites. Methods to enhance the quality of wildlife habitat and any

• bserved positive impacts to populations will be

consolidated

• Engagement and feedback to inform the final closure

design

RECLAMATION RESEARCH – FINAL LANDFORM OPTIONS TO SUPPORT WILDLIFE HABITAT

31 The De Beers Group of Companies

Un Uncer ertaint tainty: : Long term physical stability and performance of engineered covers at the PK disposal areas, as an erosion resistant barrier.

RECLAMATION RESEARCH – PHYSICAL STABILITY OF ENGINEERED COVERS AT PK AREAS

• Desktop review – research, constructability and performance

results available at similar sites.

• Geotechnical investigation – material testing and installation of

monitoring instruments

• Special studies and design considerations (e.g. constructability,

transitional layer)

Fine PK 50 1 ~1 m non-PAG rock

32 The De Beers Group of Companies

Un Uncer ertaint tainty: : Development and stability of the meromictic conditions predicted within the flooded Tuzo Pit.

• Desktop review – research findings and case

study results available at similar sites. Available methods for enhancing chemocline stability

• Comparison of key assumptions and inputs

from predictions to measured values (e.g. TDS concentration of groundwater inflows) and assessment of implications to closure

• Development of numerical closure criteria for

closure objective OP1 and also support a functioning aquatic ecosystem within Kennady Lake

RECLAMATION RESEARCH – STABILTITY OF CHEMOCLINE

https://www.imwa.info/docs/imwa_2015/IMWA2015_Herrell_091.pdf

33 The De Beers Group of Companies

Un Uncer ertaint tainty: : Water quality at end of mining, water management options at closure, and the timeline for recovery of Kennady Lake to allow reconnection

• Data collection – operational monitoring

data collected as per the Project Water Licence.

• Comparison of key assumptions and inputs

from predictions to measured values

• Development of numerical closure criteria

for closure objective KL1

• Water management options assessment – to

reduce the period of time for recovery of Kennady Lake and reconnection

RECLAMATION RESEARCH – TIMELINE FOR RECONNECTION OF KENNADY LAKE TO SURROUNDING WATERBODIES

(De Beers, 2010)

34 The De Beers Group of Companies

DISCUSSION