Giant Mine Remediation Project Annual Report 2019-2020

Measure

To prevent the significant adverse impacts on environment and the significant public concern from the proposed perpetual timeframe, the project will proceed only as an interim solution, for a maximum of 100 years.

Project comments on status

The closure period is 100 years as outlined in the Closure and Reclamation Plan. 

Measure

Every 20 years after the beginning of project implementation, the developer will commission an independent review of the project to evaluate its effectiveness to date, and to decide if a better approach can be identified. This will:

1. consider results of the ongoing research
2. be participatory in nature
3. follow the requirements of procedural fairness and be transparent in nature.

If the periodic review identifies a better approach that is feasible and cost-effective, the developer will further study it, and make the study and its results of the study public.

Project comments on status

Article 8 of the June 9, 2015 Environmental Agreement further formalized the process through which the future Independent Project Review will be conducted. The agreement ensures the independent review of the project is conducted in a manner that considers ongoing research results, is participatory and transparent in nature and follows the requirements of procedural fairness.

Measure

To facilitate active research in emerging technologies towards finding a permanent solution for dealing with arsenic at the Giant Mine site, the developer will fund research activity as advised by stakeholders and potentially affected parties through the Giant Mine Oversight Board.

The ongoing funding for this research activity, and additional resources required to manage its coordination, will be negotiated and included as part of the Environmental Agreement specified in Measure 7 and will make best use of existing research institutions and programs.

The Giant Mine Oversight Board will ensure through the research activity that, on a periodic basis:

• reports on relevant emerging technologies are produced
• research priorities are identified
• research funding is administered
• results of research are made public
• results of each cycle are applied to the next cycle of these steps

Project comments on status

Articles 7 and 11 of the June 9, 2015 Environmental Agreement provide a commitment of funding for the oversight body (which will be known publicly as the Giant Mine Oversight Board) to manage a research program as required by Measure 3. Initial funding flowed for this measure in 2016-17 and will be ongoing.

Measure

The Giant Mine Oversight Board will provide the results of the research funded by the developer to the periodic reviews of the project described in Measure 2. If better technological options are identified through the funded research in-between these periodic 20-year reviews, these will be reported publicly by the Giant Mine Oversight Board to the parties, the developer and the Canadian public. The developer will consider these technologies and make decisions regarding their feasibility. The developer will make any such decisions public.

Project comments on status

The Giant Mine Oversight Board hosted a research workshop in March 2018 and negotiated a Memorandum of Understanding with the University of Waterloo for TERRE-NET researchers to establish a formal research relationship with respect to alternate technological options for the permanent remediation solution for the arsenic trioxide dust stored at the Giant Mine site. Currently, the research focus is on stabilization of the dust; the safe extraction of the dust will be a future focus.

Measure

In order to mitigate significant adverse impacts that are otherwise likely, the developer will commission an independent Quantitative Risk Assessment to be completed before the project receives regulatory approvals. This will include:

• explicit acceptability thresholds, determined in consultation with potentially affected communities
• an examination of risks from a holistic perspective, integrating the combined environmental, social, health and financial consequences
• possible events of a worst-case/ low frequency high consequence nature
• additional considerations specified in Appendix D of the Report of Environmental Assessment

From this, the developer will identify any appropriate project improvements and identify management responses to avoid or reduce the severity of predicted unacceptable risks.

Project comments on status

An independent consultant (Wood) was retained in 2018 to complete the Quantitative Risk Assessment. A separate consultant was retained to develop the engagement component (Stratos). The report and findings will be presented during engagement sessions in Spring and Summer 2020. Results will be carried forward in design plans submitted to the Mackenzie Valley Land and Water Board and future versions of management plans and design and construction plans as required.

Measure

The developer will:

• investigate long-term funding options for the ongoing maintenance of this project and for contingencies, including a trust fund with multi-year up front funding
• involve stakeholders and the public in discussions on funding options
• make public a detailed report within 3 years that describes its consideration of funding options, providing stakeholders with the opportunity to comment on the report

Project comments on status

The Measure 6 report on long term funding options for Giant Mine was finalized in July 2019 (Deloitte LLP, 2019a).

Measure

The developer will negotiate a legally-binding environmental agreement with, at a minimum, the members of the Oversight Working Group, and other appropriate representative organizations, to create an independent oversight body (Giant Mine Oversight Board) for the project. These negotiations will build on the existing discussion paper and draft environmental agreement of the Giant Oversight Working group. This Giant Mine Oversight Board will exist for the life of the project unless otherwise agreed by the parties to the Environmental Agreement. Every effort will be made to have the Giant Mine Oversight Board in place as early as possible. The negotiations will make significant progress within 6 months of the Ministers' Environmental Assessment decision or proceed to mediation. The developer will cover any mediation costs. The Environmental Agreement will include a dispute resolution mechanism to ensure compliance with the agreement and a stable funding mechanism for the Giant Mine Oversight Board.

Project comments on status

Through negotiations with the 6 affected parties (GNWT, CIRNAC, Alternatives North, the North Slave Métis Alliance, the Yellowknives Dene First Nation, the City of Yellowknife) an Environmental Agreement was signed in June 2015. This Agreement established the mandate for a Giant Mine Oversight Board. Details of the board's mandate are included in the Giant Mine Environmental Agreement and society's by-laws found on the Giant Mine Oversight Board's website.

Measure

The activities of the oversight body will include:

• keeping track of monitoring activities by the developer and the results of those activities, including water quality and aquatic effects monitoring, health monitoring and other monitoring
• considering the adequacy of funding for the project and ongoing research
• providing advice to the developer, regulators and government on ongoing improvements in monitoring and project management to prevent risks and mitigate any potential impacts
• sharing the oversight body's conclusions with the general public and potentially affected communities in a culturally appropriate manner

Project comments on status

The Environmental Agreement provides for the creation of the oversight board and funding to fulfill these obligations going forward. Article 3 of the Environmental Agreement outlines the mandate of the Giant Mine Oversight Board. The project continues engaging with Giant Mine Oversight Board staff and directors through various engagement initiatives and venues, further described in the Engagement Plan.

Measure

The developer will work with other federal and territorial departments as necessary to design and implement a broad health effects monitoring program in Ndilǫ, Dettah and Yellowknife focusing on arsenic and any other contaminants in people which might result from this project. This will include studies of baseline health effects of these contaminants and ongoing periodic monitoring. This will be designed with input from:

• Health Canada, GNWT Health and Social Services and the Yellowknife medical community
• the Yellowknives Dene and other potentially affected communities

The organization conducting the monitoring will provide regular plain language explanations of the monitoring results in terms that are understandable to lay people, and communicate this to potentially affected communities in a culturally appropriate manner.

Project comments on status

The Health Effects Monitoring Program was established in 2017.  The program is carried out by University of Ottawa's Dr. Laurie Chan and his team. It is a long-term monitoring program to establish levels of arsenic and other contaminants of concern in residents of Ndilǫ, Dettah and Yellowknife. The results of baseline data collection phase (2 waves in 2018 and 2019) indicated: that overall arsenic levels in urine are similar between the overall Yellowknife population and the Canadian Health Measures Survey levels, which represent the general Canadian population.

Additional public sessions are intended for May 2020 to communicate more details of the results with respect to additional sample analysis.

Measure

The developer will commission a comprehensive quantitative human health risk assessment by an independent, qualified human health risk assessor selected in collaboration with Health Canada, the Yellowknives Dene, the City of Yellowknife, and the developer. This human health risk assessment will be completed before the project receives regulatory approvals. It will:

• include a critical review of the 2006 Tier II human health risk assessment and the previous screening reports
• consider additional exposures and thresholds (as specified in Appendix F of the Report of Environmental Assessment)
• decide whether a Tier III risk assessment is appropriate
• provide a plain language explanation of the results in terms that are understandable to the general public, and communicate this to potentially affected communities in a culturally appropriate manner
• provide interpretation of results and related guidance
• inform the broad health effects monitoring program (described in Measure 9 above)

The developer may conduct the human health risk assessment concurrently with the Quantitative Risk Assessment described in Measure 5. Based on the results of this human health risk assessment, and on any existing results of the health effects monitoring program (described in Measure 9 above), the developer will, if necessary in response to this information, identify, design and implement appropriate design improvements and identify appropriate management responses to avoid or reduce the severity of any predicted unacceptable health risks.

Also, footnote #133 in the Report of Environmental Assessment (Appendix D) is revised to read, in its entirety, "Including inference of causality and pathologies deducted from any available health studies."

Project comments on status

The Human Health Ecological Risk Assessment was completed by Canada North Environmental Services. The Human Health Ecological Risk Assessment was carried out with significant input from stakeholders, community members and traditional knowledge holders. This input included both the scope of the assessment and the implementation to better assess risks considering differences in traditional land use, food consumption, and lifestyles for residents living in Yellowknife, Ndilo and Dettah. The final report was released in January 2018. Additional considerations for communications are underway to ensure residents understand the outcomes which have informed public health advisories through the GNWT Department of Health and Social Services.

The project is currently developing a wellness study (formerly called the Stress Study) via an independent research team through the University of Wilfred Laurier. The requirement of this study was identified in Appendix F to the Report of Environmental Assessment noting the requirement to "evaluate indirect effects of potential exposures to arsenic on wellness, including stress effects." Preliminary scope discussions have occurred with affected parties. Implementation of the stress component will take place 2020-21. 

Measure

To prevent significant adverse impacts on Great Slave Lake from contaminated surface waters in the existing or former channel of Baker Creek, should it be re-routed to avoid the mine site, the developer will ensure that water quality at the outlet of Baker Creek channel will meet site-specific water quality objectives based on the Canadian Council of Ministers of the Environment Guidance on the Site-Specific Application of Water Quality Guidelines in Canada.

Project comments on status

Water quality objectives specific to and protective of Yellowknife Bay were developed based on Canadian Council of Ministers of the Environment guidance and are presented in the effluent quality rriteria report. Extensive modelling including a site model in GoldSim, a near field model of the mixing zone (CORMIX) and a 3D Model of Yellowknife Bay (GEMSS) were developed to support the development of effluent quality criteria and demonstrate the Project's ability to meet water quality objectives. Modelling documentation is included in the effluent quality criteria report along with prediction of future water quality in Yellowknife Bay. The water quality objectives will be met upon completion of the project active remediation phase and will be met in the vicinity of the outlet of Baker Creek (see Measure 13), at the edge of a 200 metre mixing zone (see Measure 15) that includes the project's new water treatment plant outfall and the influence of Baker Creek.

Site specific water quality objectives were presented as part of pre-engagement and submitted in the effluent quality criteria report to the Mackenzie Valley Land and Water Board for approval in April 2019. These were discussed at the first technical session in July 2019, hosted by the Mackenzie Valley Land and Water Board, in support of the water licence application process and approved by the board in July 2020.

Measure

The developer will design and, with the applicable regulators, manage the project to ensure that, with respect to arsenic and any other contaminants of potential concern, the following water quality objectives are achieved in the vicinity of the outlet of the existing or former channel of Baker Creek, should it be re-routed to avoid the mine, excluding Reach 0:

• Water quality changes due to discharge from the former channel of Baker Creek will not reduce benthic invertebrate and plankton abundance or diversity
• Water quality changes due to discharge from the former channel of Baker Creek will not harm fish health, abundance or diversity
• Water quality changes due to discharge from the former channel of Baker Creek will not adversely affect areas used as drinking water sources
• Water quality changes due to discharge from the former channel of Baker Creek will not adversely affect any traditional or recreational users

There is no increase in arsenic levels in Great Slave Lake due to discharge from the former channel of Baker Creek beyond the parameters described in Measure 12.

Project comments on status

Measure 13 a) through d) are satisfied by selecting water quality objectives for Yellowknife Bay that are protective of aquatic life and drinking water. Arsenic concentrations in Great Slave Lake, beyond the edge of the mixing zone (200 metres from breakwater), will not increase from present-day concentrations as demonstrated in the effluent quality criteria report and supporting documentation (see Measure 12).

Measure

The developer will add an ion exchange process to its proposed water treatment process to produce water treatment plant effluent that at least meets Health Canada drinking water standards (containing no more than 10μg/L of arsenic), to be released using a near shore outfall immediately offshore of the Giant Mine site instead of through the proposed diffuser. The developer will achieve this concentration without adding lake water to dilute effluent in the treatment plant.

Project comments on status

The new water treatment plant will include ion-exchange technology as part of the treatment process and will discharge effluent meeting the criteria of 10 ug/L of arsenic. The outfall location was identified through stakeholder engagement and options analysis and will be located nearshore of the Giant Mine site in the vicinity of Baker Creek. No diffuser is proposed.

Measure

The developer and regulators will design and manage the project so that, with respect to arsenic and any other contaminants of potential concern:

• Water quality at the outfall will meet the Health Canada Guidelines for Canadian Drinking Water Quality
• The following water quality objectives in the receiving environment are met:
  • Water quality changes due to effluent discharge will not reduce benthic invertebrate and plankton abundance or diversity at 200 metres from the outfall
  • Water quality changes due to effluent discharge will not harm fish health, abundance or diversity
  • Water quality changes due to effluent discharge will not adversely affect areas used as drinking water sources
  • There is no increase in arsenic levels in Yellowknife Bay water at 200 metres from the outfall
  • There is no increase in arsenic levels in Yellowknife Bay sediments at 500 metres from the outfall

Project comments on status

All parameters of potential concern will meet relevant Canadian Drinking Water Guidelines at the edge of the mixing zone.

Water quality objectives specific to Yellowknife Bay have been developed to be protective of aquatic life and drinking water and all water quality objectives will be met at the edge of the mixing zone.

Measure

Before construction, the developer will model re-suspension of arsenic from sediments and resulting bioavailability in the vicinity of the outfall. If the modeling results indicate that the outfall may re-suspend arsenic from sediments, the developer will modify the outfall design until operation does not cause resuspension of arsenic from sediment.

Project comments on status

The project is taking a more protective approach and mitigating the potential of sediment resuspension through design of a sediment cover, rather than modelling. The design criteria for the outfall will include the requirement to avoid resuspension of arsenic from sediments.

Measure

Before operating the outfall, the developer will design and implement a comprehensive aquatic effects monitoring program that is sufficient to determine if the water quality objectives listed in Measure 15 are being met. This program will:

• at a minimum, be able to identify any accumulation of arsenic over time in the water, sediment or fish in the receiving environment
• include appropriate monitoring locations near Ndilǫ, in Back Bay and in Yellowknife Bay, with a focus on areas in the vicinity of the outfall and areas used by people
• include the establishment of a baseline for aquatic effects in Back Bay before beginning. Project construction and installation of the outfall
• be developed according to Aboriginal Affairs and Northern Development Canada Guidelines for Designing and Implementing Aquatic Effects Monitoring Programs for Development Projects in the Northwest Territories, June 2009, with corresponding action levels and management response framework

Project comments on status

A draft aquatic effects monitoring program focusing on the early years of the remediation program (up to 2026) was developed, engaged upon and revised. A conceptual aquatic effects monitoring program looking forward past 2026 was also developed, engaged upon and revised. A baseline field monitoring program began in 2018-19 to develop baselines for aquatic effects in Back Bay and further afield.

Both documents (the Baker Creek aquatic effects monitoring program study design and the conceptual study design for Yellowknife Bay) were submitted to the Mackenzie Valley Land and Water Board in April 2019 and approved by the board in August 2020. Details including water licence conditions were discussed in Technical Session 1 in July 2019, Technical Session 2 in September 2019 and the Public Hearings in January 2020.

Measure

Prior to preparing chambers and stopes for freezing, the developer will conduct a comprehensive Quantitative Risk Assessment evaluating both wet and dry methods for the initial freezing design, with respect to current risks and implications for future removal. This will include an evaluation of potential effects of the proposed freezing and wetting method on the thawing or frozen excavations, and potential impacts of ongoing design changes prior to implementing the project. The developer will release a plain language report to the public describing its considerations and the resulting design.

Project comments on status

The Freeze Design Basis Report was finalized in 2016 and included an evaluation of wet versus dry methods, resulting in the selection of the dry method. The plain language report was finalized and distributed to the Giant Mine Working Group, Yellowknives Dene First Nations Giant Mine Advisory Committee, and email distribution list (June 2019).

Measure

Considering the results of the risk assessment described in Measure 18, the developer will not adopt any method of freezing that significantly reduces opportunities for future arsenic removal or other remediation by future technologies.

Project comments on status

The Freeze Design Basis Report was finalized in 2016 and included an evaluation of wet versus dry. The project is proceeding with the dry method, which combined with a passive freezing approach will allow for reversibility if needed. Closure Objective F2 and associated closure criteria address reversibility in the Closure and Reclamation Plan.

Measure

The developer will conduct all major demolition and construction activities with the potential to release large amounts of dust or contaminants into the air when wind directions will minimize the chances of dust and contaminants blowing into the City of Yellowknife, Dettah and Ndilǫ.

Project comments on status

The Dust Management and Monitoring Plan defines wind levels for carrying out site activities as well as requirements for timing of activities including demolition to be carried out during times of forecasted low winds and in a direction to minimize potential impacts to local communities. As well, the site wide Air Quality Monitoring Plan is an existing and ongoing program that was designed to adapt to changing activities on site, and will incorporate all suitable measures and activities to mitigate the risks of exposure to contaminated dust throughout the life of the project. The Air Quality Monitoring Plan is an appendix to the Dust Management and Monitoring Plan.

Measure

The developer will collect dust and contaminant level data from soil and vegetation in the vicinity of major reclamation activities before and after major demolition or construction activities to serve as a baseline for any related adaptive management activities that may follow.

Project comments on status

As was conducted during the Roaster Complex deconstruction, air quality monitoring (including activity-specific) as per the Air Quality Monitoring Program will be conducted for all major reclamation activities (both before and after) with adaptive mitigative measures applied as required. Activity specific monitoring such as dust and contaminant level data from soil and vegetation in the vicinity of major reclamation activities will be identified in future plans.

Measure

The developer will conduct a study to determine appropriate depth of the tailings cap and B1 pit cover, in consultation with Environment Canada and responsible regulators, to verify that the depth proposed will ensure the tailings cap and B1 pit cover are not compromised by vegetation growth. The developer will provide a report of this study to the Mackenzie Valley Land and Water Board before it issues a water licence for the project.

Project comments on status

During Surface Design Engagement some affected parties preferred the selection of a non-vegetated tailings cover. The selection of a rock cover as outlined in the Closure and Reclamation Plan addresses the concern of the cover being compromised by vegetation growth. As a result of input received during engagement and the selection of a rock cover, this measure has been addressed.

Measure

The developer will work cooperatively with responsible regulatory authorities and interested parties in the development and submission of a Tailings Management and Monitoring Plan prior to receiving regulatory approvals. This plan will not only identify potential issues for the management of tailings but will also identify mitigation measures to prevent problems related to the tailings cap failure, and will include consideration of the B1 pit cover as applicable.

Project comments on status

A Tailings Management and Monitoring Plan has been developed.

Measure

The developer will physically prevent all-terrain vehicle access to the tailings cap and B1 pit cover to prevent the surface from being eroded or otherwise compromised. The developer will monitor the effectiveness of this prevention, and will take any additional management measures as necessary to prevent all-terrain vehicle access.

Project comments on status

The selection of a coarse rock cover will prevent the surface from being eroded or comprised through all-terrain vehicle access. Closure objective T6 addresses this in the Closure and Reclamation Plan.

Measure

The developer will work cooperatively with responsible regulatory authorities and interested parties in the development and submission of an Air Quality Management Plan which incorporates an ongoing air quality monitoring program. This ongoing monitoring program will include all previously identified on-site air quality monitoring stations and one off-site air quality monitoring station near Niven Lake. At a minimum, ambient concentrations of nitrogen dioxide and PM2.5 will be monitored at the Niven Lake site. Total suspended particulate and metal concentrations will be monitoring at the on-site locations. This Air Quality Management Plan will identify action levels and trigger additional management and mitigation activities, if required.

Project comments on status

The Air Quality Management Plan comprises 8 site perimeter stations and three community stations. The parameters nitrogen dioxide and PM2.5 are included at the community stations, including Niven. The Air Quality Management Plan, in conjunction with the Dust Management and Monitoring Plan, identifies action levels which trigger additional management and mitigation measures as required.

Measure

In conjunction with Measure 10 above, the developer will consider the results of the comprehensive human health risk assessment, and consult with the Yellowknives Dene First Nation and City of Yellowknife when determining suitable end uses of the site, to ensure that those proposed uses do not pose a health risk to people, including toddlers.

Project comments on status

The Human Health Ecological Risk Assessment was completed in 2018 and results were presented to the Yellowknives Dene First Nation, the City of Yellowknife and other affected parties. The constraints to end land use are presented in the Closure and Reclamation Plan. The Engagement Plan outlines the extensive number of engagement activities that have taken place on the Human Health Ecological Risk Assessment and the Closure and Reclamation Plan. The project team will continue to work with its municipal, territorial and federal counterparts to communicate site risks and end land use constraints.

Suggestion

The developer should consult with surrounding communities, including Dettah, Ndilǫ and the City of Yellowknife, prior to finalizing its project design, so that design improvements may be incorporated to address any remaining concerns.

Project comments on status

The extensive engagement completed since the Environmental Assessment is documented in the Closure and Reclamation Plan, Engagement Plan and the Engagement Log. This includes the Surface Design Engagement process and regular ongoing engagement through the Giant Mine Working Group, the Yellowknives Dene First Nation Giant Mine Advisory Committee and other engagement venues.

Suggestion

The developer should create a monument as a memorial to the impacts of past contamination from Giant Mine on Indigenous communities and the environment.

Project comments on status

The project has committed to a monument as this was widely supported by affected parties during Surface Design Engagement, however the details of exactly what and where the monument would go were not discussed during Surface Design Engagement. The project will engage on this with affected parties prior to finalizing the details of the monument and communicate this decision to the public.

Suggestion

To encourage widespread learning from and remembering of the experiences of the Giant Mine, the Developer, in conjunction with the GNWT Department of Education, Culture and Employment, should:

• develop an education resource unit on the impacts of Giant Mine on the land and on people, including impacts on Indigenous peoples
• distribute this resource unit for use within the school curriculum across Canada

Project comments on status

The project is working with the Yellowknives Dene First Nation, North Slave Métis Alliance, Giant Mine Oversight Board, and GNWT Education, Culture and Employment to develop a Giant Mine education resource for the Grade 10 Northern Studies curriculum.

Suggestion

The Federal Contaminated Sites Action Program should develop a policy framework and guidance for the perpetual care and management of remediated contaminated sites.

Project comments on status

A Perpetual Care Plan is a requirement under the Environmental Agreement. Under the agreement, a draft was to be available to the Giant Mine Oversight Board by June 2020; however, the project requested a formal extension from the Giant Mine Oversight Board until November 2020 to account for incorporating the results of the Quantitative Risk Assessment. A draft Perpetual Care Plan framework was submitted to the Giant Mine Working Group in August 2020 for feedback prior to the Giant Mine Oversight Board submission. The project began engagement in 2019-20.

Suggestion

To reduce public concern about the multiple roles of Aboriginal Affairs and Northern Development Canada in this project and to increase public confidence, Aboriginal Affairs and Northern Development Canada should produce guidelines to clarify reporting structures to ensure that project inspectors, advisors and managers employed by the federal government can perform their duties objectively and without undue pressure from within the federal government. These should be made available to the public within 6 months of Ministerial acceptance of this Report of Environmental Assessment.

Project comments on status

A response to this suggestion is outside the mandate of the project, however the existing Treasury Board Values and Ethics Code for the Public Sector is available to the public.

Suggestion

Based on the results of the health risk assessment described in Measure 10, the appropriate government authorities should remediate garden and playground soils where arsenic concentrations exceed current guidelines for urban soils in Canada.

Project comments on status

The remediation of garden and playground soils is out of scope of the Giant Mine Remediation Project. The project continues to cooperate with relevant federal and territorial agencies to share information.

Suggestion

The developer should consider the Trail Human and Environmental Health Committee as a model for the development of the health program.

Project comments on status

The Health Effects Monitoring Program has incorporated lessons learned and similar concepts from that of the Trail BC Monitoring Program.

Suggestion

During its review of the diversion of Baker Creek, the Department of Fisheries and Oceans should consider the habitat loss of the existing Baker Creek and decide on any habitat design requirements for the diversion to the extent it deems appropriate. Any resulting habitat compensation requirements should be applied on the new diversion.

Project comments on status

The project is working with the Department of Fisheries and Oceans with respect to habitat loss and compensation. Discussions began in 2018 and continued in 2019-20. The project is committed to engage with the Working Group, the Giant Mine Advisory Committee, and the affected parties to determine the appropriate habitat design requirements are incorporated into the final design of Baker Creek.

Suggestion

The developer should investigate the potential advantages and disadvantages of adding an engineered wetland to the Project to reduce arsenic in surface drainage. This investigation should include possible locations in the channel that formerly contained Baker Creek and in the Baker Creek diversion. On completion, the developer should make a public report of the results of this investigation and of any resulting changes to project design. This should be completed before a water license is issued for the project.

Project comments on status

A Research and Reclamation Plan entitled Passive and Semi Passive Treatment systems is an Appendix to the Closure and Reclamation Plan. This plan outlines research undertaken to date on engineered wetlands and the proposed further steps to investigate the feasibility and potential effectiveness of applying passive and semi-passive treatment systems on the Giant Mine site.

Suggestion

To manage the risks of airborne exposure of contaminated dust from deconstruction of buildings or other structures on site, the developer should:

• prepare a dispersion model of dust plume given typical wind direction and speed
• define the meteorological window of opportunity to describe acceptable wind conditions to eliminate the potential for a dust cloud release and transport of surrounding communities
• consult a meteorologist to develop a sound model of weather conditions, to indicate when winds are steady and not gusting, blowing to the north stop if winds change or any dust controlling equipment fails

Project comments on status

The Air Quality Monitoring Program is an existing and ongoing program that was designed to adapt to changing activities on site, and will incorporate all suitable measures and activities to mitigate the risks of exposure to contaminated dust throughout the life of the project. Activity-specific monitoring and mitigations measures will be a part of specific construction plans, including deconstruction of buildings as required.

Suggestion

To prevent impacts on people from potentially harmful contaminant releases from deconstruction of buildings or other structures on site at the Giant Mine site, the Land and Water Board should specify allowable wind directions and wind speeds in degrees, to ensure that contaminated structures are not demolished during blustery multi-directional winds at ground level.

Project comments on status

The Air Quality Monitoring Program is an existing and ongoing program that was designed to adapt to changing activities on site, and will incorporate all suitable measures and activities to mitigate the risks of exposure to contaminated dust throughout the life of the project. Activity-specific monitoring and mitigations measures will be a part of specific construction plans, including deconstruction of buildings as required.

Suggestion

The developer should investigate options for filling in the pits, in consultation with the City of Yellowknife and the Yellowknives Dene First Nation.

Project comments on status

The option to fill pits was investigated and outlined in the Open Pits Options Assessment Report. Pit filling options were evaluated and engaged on during the Surface Design Engagement, where there was support from most affected parties to fill pits. As outlined in the Closure and Reclamation Plan, the pits will be filled or partially filled.

Suggestion

The developer should consider the baseline conditions for existing fish habitat in Back Bay (including a fish habitat assessment in the area of the foreshore tailings and the aquatic effects baseline required in Measure 17) and develop a foreshore tailings cover design and foreshore tailings monitoring and mitigation plan for review by the Department of Fisheries and Oceans pursuant to habitat provisions of the Fisheries Act.

Project comments on status

Fish habitat surveys of the foreshore tailing areas, the near shore contaminated sediments and the outfall area in Yellowknife Bay began in 2018 and will continue in 2020-21. This work will inform and be presented in the project's application for Department of Fisheries and Oceans Canada Authorization. A conceptual level Aquatic Effects Monitoring Program for Yellowknife Bay has been developed.

Suggestion

The developer should consult with the City of Yellowknife in the design of any landfill on the Giant Mine site.

Project comments on status

Engagement sessions occurred with the City of Yellowknife through the Giant Mine Working Group and in the City-project monthly meetings to present the proposed locations and other details of the on-site landfill, resulting in support of the proposed location in the Closure and Reclamation Plan. Future design details will be made available for review by affected parties through construction plans.

Suggestion

The developer should consult with Indigenous groups with respect to reduced traditional use cumulatively resulting from the proposed project in combination with contamination from Giant Mine. This should occur prior to finalizing project design, so that design improvements may be used to address any remaining concerns.

Project comments on status

The extensive engagement completed by the project is documented in the Closure and Reclamation Plan, Engagement Plan and Engagement Log. Traditional Knowledge studies have been completed by both North Slave Métis Alliance and the Yellowknives Dene First Nation and the outcomes of that work will further inform future versions of monitoring and management plans, design plans, and construction plans as required.