Mack Mackenzie V enzie Valle lley Land and W Land and Water Boar - - PowerPoint PPT Presentation

Mack Mackenzie V enzie Valle lley Land and W Land and Water Boar r Board Public Hearing Public Hearing Closure and R Closure and Reclamation Plan Par clamation Plan Part 2 2 and Monit and Monitoring ring Januar January 2020 y 2020

2

Water and r and Monit Monitoring at ring at Giant Mine Giant Mine

• Baker Creek
• Existing effluent treatment plant (ETP)
• New water treatment plant (WTP)
• Effluent quality criteria (EQC)
• Aquatic effects monitoring program (AEMP) and other

aquatic monitoring

• Air quality and greenhouse gas emissions

3

Bak Baker Creek r Creek

Reach 0 Reach 1 Reach 2 Reach 3 Reach 4 Reach 5 Reach 6

4

• Flooding
• Exposure to Contamination
• Flooding of underground via pits
• Exposure to contamination

Bak Baker Creek – r Creek – Risks Risks

5

Bak Baker Creek – r Creek – Mitigations itigations

• Contaminated sediment removal
• Floodplain improvements – probable maximum flood

6

Flood that comes from the most severe weather that can be imagined Extremely unlikely to happen

What is the Pr What is the Probable Maximum Flood (PMF)?

• bable Maximum Flood (PMF)?

Reviewer comments ORS 5; YDFKN 21

7

Develop estimate for the worst storm that could happen given where the site is located For Baker Creek:

• Estimated 30cm of rain in 48 hours
• Assumed much snow on the ground had fallen

(1‐in‐100‐year snowpack)

• Roughly the same as assuming the amount of snow and rain

that falls in Yellowknife in one year had fallen in two days on top of a record‐year snowpack

Ho How Do W w Do We Estimat Estimate The PMF? The PMF?

8

PMF for Baker Creek would be the same as the North Saskatchewan River, in Edmonton, or 5 times the average flow in the Yellowknife River

Bak Baker Creek – r Creek – PMF MF

9

• Baker Creek will have a channel and a floodplain
• Regular flow will be confined to the channel
• Extreme floods will flow in the channel and floodplain
• Heavy rock protection will be built on the edges of the

floodplain where needed to prevent erosion

Bak Baker Creek – r Creek – Designed f esigned for the PMF r the PMF

10

Proponent Position The probable maximum flood is very conservative The Baker Creek design provides protection from even the most extreme flood events Details regarding freeboard for each pit will be provided in the Design Plan

Recommendation AN 5

Int Intervention – ention – Additional F dditional Freeboar eeboard

11

Proponent Position Proposed closure activities for Baker Creek will fulfill the promises of the Developer’s Assessment Report Criteria BC 5‐2 and BC 5‐3 are under‐development and specific to benthics and fish Criteria will be informed by engagement with stakeholders in 2020 and by guidance provided by Fisheries and Oceans Canada through Fisheries Act authorization process GMRP has committed to pre‐engagement on all criteria under‐development with the Working Group

Recommendations CoY 8, YKDFN 2

Int Intervener Theme – ener Theme – Bak Baker Creek Crit r Creek Criteria and Pr eria and Productivity

• ductivity

12

Proponent Position Priority must be given to conveying the PMF – alignment is dictated by geometry and topography Impacts to operations to Yellowknife Historical Society will be minimized where possible

Recommendations YKHS 3, 4

Int Intervention Bak ention Baker Creek and Im r Creek and Impacts t pacts to T Townsit wnsite Area Area

13

Water T r Treatment eatment

14

• Minewater is treated with existing

effluent treatment plant (ETP) built in 1981

• Seasonal discharge to Baker Creek
• Continued use of the existing ETP for

next several years, no major upgrades proposed

• A new long‐term Water Treatment

Plant (WTP) will be built onsite

Existing Ef Existing Effluent T fluent Treatment Plant eatment Plant

15

• Proposed effluent quality criteria for the ETP

reflect existing treatment technology

• Reviewer comments incorporated through

water licence process

• Metal and Diamond Mining Effluent

Regulations (MDMER) limits used to start

• If past/predicted concentrations were well

below the MDMER limits, EQC lowered

• New EQC for nitrate, ammonia, sulphate

and chloride

• From two intervenors: the proposed EQC are

“adequately protective of Baker Creek”, and “the rationales for proposed criteria seem reasonable”

Existing Ef Existing Effluent fluent Treatment Plant eatment Plant

16

A new WTP will be commissioned by approximately 2026 The new plant will:

• Operate in the central core area of site
• Continue to pump from the underground
• Discharge year‐round to Yellowknife Bay

via nearshore outfall

• Discharge much lower arsenic than ETP

(10 µg/L compared to 300 µg/L from ETP)

Ne New W w Water T r Treatment Plant (W eatment Plant (WTP) TP)

17

• Proposed a combined mixing

zone (Baker Creek and WTP)

• One set of water quality
• bjectives (WQOs) to be met at

the edge of the mixing zone

• In the future, concentrations

expected to:

• Decrease rapidly with

distance from the breakwater

• Meet WQOs at the mixing

zone boundary and into Yellowknife Bay

Water T r Treatment Plant eatment Plant

18

Parameter Existing ETP New WTP Maximum Average Concentration Maximum Grab Concentration Maximum Average Concentration Maximum Grab Concentration

pH 6.5 to 8.5 6.5 to 8.0 TSS, mg/L 15 30 15 30 Sulphate, mg/L 1310 1440 ‐ ‐ Chloride, mg/L 660 720 ‐ ‐ Nitrate, mg‐N/L 13 25 13 25 Total Ammonia (variable), mg‐N/L pH 6.5 3.1 6.2 10.9 22 Refer to Table 7 in IR Response #06 from Tech Session 2 pH 8.5 0.51 1.0 ‐ ‐

Total antimony, mg/L ‐ ‐ 0.2 0.3 Total arsenic, mg/L 0.3 0.6 0.01 0.02 Total copper, mg/L 0.03 0.06 0.024 0.033 Total lead, mg/L 0.003 0.006 0.003 0.008 Total nickel, mg/L 0.10 0.20 0.10 0.15 Total zinc, mg/L 0.10 0.20 0.08 0.16 Total petroleum hydrocarbons, mg/L 3 5 3 5 Un‐ionized ammonia, mg‐N/L* 0.5 1.0 0.5 1.0 Radium‐226, Bq/L* 0.37 1.11 0.37 1.11 Cyanide, mg/L* 0.03 0.06 0.5 1

*EQC included only to align with MDMER limits, parameters not identified as COPC

Pr Proposed EQC

• posed EQC

19

Proponent Position Effluent quality criteria for chloride and sulphate for water treatment plant are not required

• Low discharge volume
• High assimilative capacity
• Low concentrations of chloride and sulphate at mixing zone boundary

(< 10 and 20 mg/L respectively, well below WQOs) In lieu of setting EQC for chloride and sulphate for the WTP:

• Monitor influent and effluent
• Track against predictions
• Report results in Surveillance Network Program and AEMP

Recommendations GMOB 13, SEC 10

Int Intervener Theme – ener Theme – Effluent Crit luent Criteria f eria for W r WTP

20

Monitoring now and in the future will be both:

• Site‐wide
• Yellowknife Bay

Monit Monitoring ring

21

See Standard Operating Procedures for Details

• Stations, description, project phase,

rationale, frequency, parameters

SNP 43‐5

Trapper Creek Pocket Lake Baker Pond ETP discharge

P‐LA SNP 43‐11 SNP 43‐16 SNP 43‐1 Baker Creek Exp Pt SNP 43‐23 (new)

Monitoring across the Site—Current and Future

• Runoff
• Trapper Creek
• Pocket Lake
• Baker Creek (upper,

middle, lower)

• Ponds
• TCAs
• Sumps
• Groundwater
• Mine pool
• ETP/WTP inflow

and outflow

Site te-Wide W Wate ter M Monito toring

22

Proponent Position GMRP does not consider more frequent sampling necessary:

• The current water quality sampling regime for

Baker Creek downstream of discharge is bi‐ monthly during the open water season

• The ETP discharges seasonally, typically from

July to September

• The creek freezes to the bottom in many places

during the winter

Int Intervention – ention – Wat ater Quality Sam er Quality Sampling ling Freq equency of Bak uency of Baker Creek r Creek

Recommendations NSMA 3, 5

23

Proponent Position GMRP does not consider more frequent sampling necessary:

• Effects of existing contamination on Baker

Creek are well understood

• Frequency is standard for environmental

effects monitoring under MDMER and AEMP

Recommendation NSMA 5

Int Intervention – ention – Fish and Fish and Benthics Benthics Sam Sampling F ling Freq equency uency

24

Proponent Position The GMRP uses a standard, comprehensive suite of parameters at all water quality monitoring stations. Details are provided in the standard

• peration procedures

Parameters recommended by Alternatives North are already included in the standard suite of parameters

Recommendation AN 13

Int Intervention – ention – Monit

• nitoring Parame
• ring Parameters

25

MDMER/EEM OMP SNP

Surface W Wate ter M Monito toring

• Surveillance network program (SNP)

stations

• Surface Runoff Stations sampled under
• perational monitoring program
• Details are provided in the standard
• perating procedures document submitted

as part of the GMRP water licence application

26

Yellowknife River Behind and beyond the breakwater Near the proposed outfall

Dettah

Near old townsite Back Bay North Yellowknife Bay Near Dettah

Stations throughout Yellowknife Bay

Near City Pumphouse 2 Near Ndilǫ

Yellowknife

Yello llowknif wknife Ba Bay – y – Special Study pecial Study Existing Conditions Existing Conditions

27

Int Intervener Theme – ener Theme – Runof unoff Monit f Monitoring ring and Crit and Criteria eria

Proponent Position The existing runoff monitoring network includes the monitoring tributaries upstream of Baker Creek GMRP commits to re‐evaluating runoff criteria submitted in the water management and monitoring plan The GMRP will develop action levels for runoff from engineered covers

Recommendations GMOB 10, 11; ECCC 2, SEC 3

28

Int Intervention – ention – Yello ellowknif wknife Ba Bay Sam Sampling F ling Freq equency uency

Proponent Position

GMRP does not consider more frequent monitoring necessary :

• GMRP has enough existing data to understand

seasonal trends

• GMRP has proposed sampling that captures early
• pen‐water season, late open‐water season, and

under‐ice conditions

• GMRP expects a formal plume study for discharge

to Yellowknife Bay

Recommendations NSMA 3, 4

29

Proponent Position The GMRP has committed to engage further on Aquatic Effects Monitoring Program GMRP is developing a coordinated approach to engaging on:

• Fisheries Act authorization
• Baker Creek design
• AEMP
• Community‐based Monitoring

Program GMRP has proposed an Aquatics Engagement Group GMRP welcomes input from the YKDFN and notes that there will be

• pportunities to improve the AEMP

throughout the term of the Water Licence

Int Intervener Theme – ener Theme – Stak takeholder In holder Input put to to t the A AEMP

Recommendations ECCC 3; YKDFN 6, 10

30

Proponent Response GMRP agrees to an approach with one AEMP, with a shift in focus from Baker Creek to Yellowknife Bay at the time of WTP transition Propose approval of the “Baker Creek” AEMP study design Subsequent re‐evaluations will allow for change in focus to Yellowknife Bay

Int Intervener Theme – ener Theme – Single ingle AEMP AEMP

Recommendations SEC 9, GMOB 15

31

Int Intervener Theme – ener Theme – AEMP t EMP to Measure Measure Im Impr provem ements ents

Recommendations GMOB 16, SEC 9

Proponent Position Improvements to the aquatic environment will not be realized until later in the remediation project GMRP has committed to providing a Table of Contents for the Post‐Closure Monitoring and Maintenance Plan in 2025 Multiple AEMP re‐evaluations between now and end

• f remediation

32

Air Quality and Greenhouse Gases Air Quality and Greenhouse Gases

33

Int Intervention – ention – CAA AAQS and QS and Mitigation Mitigation Measures F Measures For An A r An Activ tive F Freeze eeze

Proponent Posion GMRP will continue to follow the GNWT standards If GNWT adopts Canadian Ambient Air Quality Standards (CAAQS), GMRP will follow Not necessary to include mitigation measures for an active freeze system and associated emissions, passive system proposed in the CRP

Recommendation ECCC 4

34

Int Intervener Theme – ener Theme – Greenhouse Gases reenhouse Gases

Proponent Position GMRP considers it important to look for ways to reduce its greenhouse gas (GHG) emissions All significant decisions on closure options and activities are complete, therefore the GMRP does not see a benefit of an assessment of GHG emissions related to options selection Investigation of alternative energy sources is underway GMRP will continue to look for ways to reduce the carbon footprint of the Project i.e. efficient use of borrow and reducing haul distances where possible

Recommendations AN 7, GMOB 17

35

• The Giant Mine Remediation

Project’s Closure and Reclamation Plan is a comprehensive document based on many years of study and engagement

• Remediation of the Giant Mine is

important to reduce risks to the environment and health and safety for people in the Yellowknife area

• Further revisions and submissions
• f the CRP will only lead to delays

to mitigating risks

• The GMRP has proposed a process

to allow for review and approval of final design details

Summar Summary

36

The Project will result in long‐term improvements of the soil, water, sediment and create a safer community The GMRP team looks forward to continuing to working with our stakeholders to deliver this important project

Summar Summary

37

Mahsi Cho Mahsi Cho