Subject: W2012L2-0001, Wastewater and Processed Kimberlite Management Plan Version 9.0, Ekati Mine, NT

Transcription

1 Dominion Diamond Mines ULC Street SW (403) Calgary, Alberta T2P 1T1 (403) fax March 22, 2019 Mr. Joseph Mackenzie Chair Wek èezhìi Land and Water Board #1, th Street Yellowknife, NT, X1A 3S3 Subject: W2012L2-0001, Wastewater and Processed Kimberlite Management Plan Version 9.0, Ekati Mine, NT Dominion Diamond Mines ULC (Dominion) is pleased to submit Version 9.0 of the Ekati mine Wastewater and Processed Kimberlite Management Plan (WPKMP) for approval by the Wek èezhìi Land and Water Board (WLWB). This submission addresses the Directives in the WLWB Reasons for Decision on Version 8.0 of the WPKMP 1 and proposes a change in operational monitoring at the Long Lake Containment Facility (LLCF) and for the Panda/Koala fine processed kimberlite (FPK) pipeline. WPKMP Version 8.0 and WLWB Directives The changes proposed and approved for WPKMP Version 8 were primarily concerned with the deposition of Fine Processed Kimberlite (FPK) into the Panda/Koala Processed Kimberlite Containment Area. WLWB Directives from the approval of WPKMP Version 8.0 required Dominion to complete the following revisions to the WPKMP: Revision A: The Board requires Dominion to revise the WPKMP to clarify that the freshwater cap depth has not yet been approved. Revision B: The Board requires Dominion to revise the WPKMP to include a closure and reclamation planning section. Dominion has incorporated these items (see Table 1.2) into the attached version of the WPKMP. WPKMP Version 9.0 In addition to addressing the WLWB Directives referenced above, Dominion has included an additional related change to operational monitoring in this version of the WPKMP. As this is a proposed change to a Board approved management plan, Dominion has submitted this plan as Version 9.0. The requested change is as follows: 1 Available on the WLWB online public registry Record #: HSE RCD ENV 1153 Document Owner: Environment Department Date: 20-March Template # EKA TEM

2 Dominion Diamond Mines ULC Street SW (403) Calgary, Alberta T2P 1T1 (403) fax Change Section 5.4, PKCA Operational Monitoring, bullet 1 from: Twice per 12-hour shift visual inspection of the current Discharge locations and the road-accessible perimeter of Cells A (north road), C (east road) and Beartooth Pit pipeline. to (two bullets): Once per 12-hour shift visual inspection of active FPK Discharge spigot locations at the LLCF, and the road-accessible perimeter of Cells A and C to active FPK spigot discharge locations. Once per 12-hour shift visual inspection of the Beartooth and Panda/Koala FPK pipelines when active. As background, the formalized requirement for two inspections every 12-hour shift of the LLCF perimeter was introduced into the WPKMP in response to a previous unplanned release of FPK from the upstream end of Cell B. This monitoring frequency of two inspections every 12-hour shift was one of a number of measures intended to mitigate the risk of a similar occurrence during subsequent FPK deposition in the upstream area of Cell A. FPK deposition in the upstream area of Cell A from the Cell A North Road is nearly completed and there are no plans for further deposition from a Cell A south road (not constructed) given the transition to FPK deposition into the Panda/ Koala PKCA. There is a substantially lower environmental risk related to FPK deposition at the planned locations within the central/lower areas of Cells A and C as compared to the upstream areas of Cells A and B. Therefore, operational monitoring at the LLCF is now more appropriately focused on active deposition areas at a frequency more comparable to the lower level of risk (i.e., new bullet #1). Additionally, Dominion suggests that the WPKMP should formalize operational monitoring of the Panda/Koala FPK pipeline (i.e., new bullet #2). The plan has also been updated to include the new the Metal and Diamond Mining Effluent Regulations (MDMER) and the reclamation and closure of the Panda, Koala and Koala North Underground mine workings. If you have any questions or concerns, please feel free to contact the undersigned at lukas.novy@ddcorp.ca or ext Lukas Novy, M.Sc, P.Eng Team Leader LOM Environment Planning Record #: HSE RCD ENV 1153 Document Owner: Environment Department Date: 20-March Template # EKA TEM

3 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan Version 9.0

4 Table of Contents Table of Contents... i List of Figures... iv List of Tables... v List of Appendices... vi Abbreviations... vii Units of Measurement... viii 1. Introduction Preface Limitations Changes for Version Wastewater and Processed Kimberlite Sources Minewater Sewage Processed Kimberlite Management of Minewater Overview Management of Surface Minewater Main Camp and Fuel Storage Berms Ammonia Nitrate Storage Facility and Polar Explosives Building Roads and Laydowns Misery Site Fox Site Pigeon Site Lynx Site Sable Site Jay Site Management of Open Pit Minewater Panda, Koala North and Koala Pits Fox Pit Misery Pit Beartooth Pit Pigeon Pit Lynx Pit Sable Pit Jay Pit Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V.9.0 i

5 2.4 Management of Underground Minewater Panda/Koala/Koala North Workings Misery Workings Management of Sewage Management of Processed Kimberlite Diamond Separation Process Size Reduction, Washing (Scrubbing), and Screening Primary Concentration Secondary Concentration Flocculants Process Water Processed Kimberlite FPK Physical Properties Kimberlite Geochemical Characterization Long Lake Containment Facility PKCA Facility Description Water Management Beartooth PKCA Facility Description Water Management Panda/Koala PKCA Facility Description Water Management Fine Processed Kimberlite Deposition Plan Background Deposition Plan Monitoring and Response Programs Minewater Receiving Environment Groundwater PKCA Operational Monitoring Long Lake Containment Facility Beartooth PKCA Panda/Koala PKCA Other Minewater Management Facilities Special Studies Adaptive Management Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V.9.0 ii

6 6. Closure and Reclamation Long Lake Containment Facility Beartooth, Panda, Koala and Koala North Pits Misery Pit Jay Pit and Dike References... R-1 Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V.9.0 iii

7 List of Figures Figure 1 Life of Mine Plan F-1 Figure 2 Ekati Diamond Mine Satellite Imagery F-2 Figure 3 Ekati Main Camp Area Satellite Imagery, 2017 F-3 Figure 4 Misery Site Satellite Imagery, 2017 F-4 Figure 5 Fox Site Satellite Imagery, 2017 F-5 Figure 6 Pigeon Site Satellite Imagery, 2017 F-6 Figure 7 Lynx Site Satellite Imagery, 2017 F-7 Figure 8 Sable Site Satellite Imagery, 2018 F-8 Figure 9 Jay Project Development Map (Jay, Misery and Lynx Sites) F-9 Figure 10 Main Camp Site Surface Minewater Collection F-10 Figure 11 Minewater and Processed Kimberlite Management at the Ekati Main Site F-11 Figure 12 Water Management for Misery Site, Current Configuration F-12 Figure 13 Water Management for the Sable Pit Area F-13 Figure 14 Minewater Management at Misery Site for Jay Project F-14 Figure 15 Ekati Diamond Mine Water and Liquid Waste Summary F-15 Figure 16 Ekati Diamond Mine Solid Waste Summary F-16 Figure 17 Long Lake Containment Facility F-17 Figure 18 The Reclaim Water Barge in Cell D of the LLCF F-18 Figure 19 Processed Kimberlite Deposition (blue arrow) into the Mined-out Beartooth Pit F-19 Figure 20 Beartooth Pit Minewater Decanting F-19 Figure 21 LLCF Area Current Extent and Closure Plan F-20 Figure 22 Beartooth, Panda, Koala and Koala North Existing and Final Configuration F-21 Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V.9.0 iv

8 List of Tables Table 1.1 Previous Versions of the Plan 1-2 Table 1.2 Primary Changes for Version Table 4.1 Fine Processed Kimberlite Volumes Associated with Deposition Options 4-10 Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V.9.0 v

9 List of Appendices Appendix A Appendix B Concordance with Water Licence Requirements for the Wastewater and Processed Kimberlite Management Plan Process Plant Description Revised July 2018 Wastewater and Processed Kimberlite Management Plan Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V.9.0 vi

10 Abbreviations Abbreviation ABA ARD Board, the CPK CPT Dominion EFPK EQC Ekati mine FDP FPK ICRP LLCF MDMER PAG PK PKCA Panda/Koala PKCA SNP TDS TRSP TSM TSS WLWB WPKMP WROMP WRSA Definition Acid-Base Accounting Acid Rock Drainage Wek'èezhıı Land and Water Board Coarse processed kimberlite Cone Penetration Testing Dominion Diamond Ekati ULC Extra fine processed kimberlite Effluent Quality Criteria Ekati Diamond Mine Final Discharge Point Fine processed kimberlite Interim Closure and Reclamation Plan Long Lake Containment Facility Metal and Diamond Mining Effluent Regulations Potentially acid generating Processed kimberlite Processed Kimberlite Containment Area Panda, Koala North and Koala pits and associated underground workings Surveillance Network Program Total dissolved solids Two Rock Sedimentation Pond Towards Sustainable Mining Total suspended solids Wek'èezhıì Land and Water Board Wastewater and Processed Kimberlite Management Plan Waste Rock and Ore Storage Management Plan Waste rock storage area Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V.9.0 vii

11 Units of Measurement Unit Definition % percent km m m 3 masl mm Mm 3 kilometre metre cubic metres metres above sea level millimetre million cubic metres Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V.9.0 viii

12 1. Introduction 1.1 Preface Dominion Diamond Ekati ULC (Dominion) is committed to protecting the environment and creating a culture of environmental stewardship. In order to align this core value and demonstrate corporate support for the management of tailings at the Ekati Diamond Mine (Ekati mine), the Chief Executive Officer and the Chief Operating Officer of Dominion hold ultimate accountable for tailings management in accordance with The Mining Association of Canada s Towards Sustainable Mining (TSM) Tailings Management Protocol and Dominion s Sustainable Development Policy. Components of the TSM Tailings Management Protocol include having a formal policy in place and have implemented a tailings management system, of which this document is a part. The Dominion Sustainable Development Policy outlines the Company s commitment to setting targets and objectives for continuous improvement around the management of tailings. A Wastewater and Processed Kimberlite Management Plan (WPKMP; the Plan) is a requirement of Type A Water Licence W2012L (the Water Licence) for the Ekati mine. The WPKMP is intended to ensure that wastewater and Fine Processed Kimberlite (FPK) are managed in accordance with the Water Licence and good practice. The Water Licence has an expiry date of August 18, The WPKMP is an operational management plan that describes the deposition of FPK within designated Processed Kimberlite Containment Areas (PKCAs) and describes site-wide wastewater management. Monitoring and Response Programs are described. In order to avoid regulatory duplication and inconsistency between management plans, this Plan does not address water and processed kimberlite management activities that are specifically regulated and approved through separate management plans and approvals, such as: Management of Waste Rock Storage Area (WRSA) seepage, which is regulated and approved by the WLWB through the Waste Rock and Ore Storage Management Plan (WROMP) under Part H Condition 2 of the Water Licence; Management of Coarse Processed Kimberlite (CPK), which is regulated and approved by the WLWB though the Waste Rock and Ore Storage Management Plan (WROMP) under Part H Condition 2 of the Water Licence; Dewatering and Drawdown activities, which are regulated and approved by the WLWB through project-specific Dewatering and Drawdown Plans under Part E of the Water Licence; Management of water for construction activities, which is regulated and approved by the WLWB through project-specific Construction Plans under Part F of the Water Licence; and Summary of Closure and Reclamation planning and activities, which is regulated and approved by the WLWB through the Interim Closure and Reclamation Plan under Part K of the Water Licence. Throughout this Plan, words and phrases that are defined in the Water Licence and that are intended to be interpreted herein as defined in the Water Licence are capitalized. This Plan is Version 9.0 of the WPKMP; previous versions and the general rationale for each are listed in Table 1.1. Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V

13 Table 1.1 Previous Versions of the Plan Plan Title or Version Year Approved Primary Change Wastewater and Tailings Management Plan 1998 (report date) Initial WPKMP WPKMP 2000 to 2004 (report dates) Operational updates. WPKMP 2006 Incorporate outcomes of 2004/05 LLCF options review. WPKMP 2008 Address WLWB Directives. WPKMP, Versions 1.0, Use of the mined-out Beartooth pit as a Minewater retention pond. Version Use of Beartooth Pit as a PKCA. Version Amalgamate Geochemical Characterization and Metal Leaching Management Plan and address WLWB Directives. Versions 4.0, Inclusions for Pigeon Pit development Versions 5.0, Inclusions for Lynx Pit development Versions 6.0, Inclusions for Sable Pit development. Version Inclusions for Jay Pit development. Version Inclusions for use of Panda/Koala PKCA and Misery Underground Project. Version 9.0 (this Plan) Under review Inclusions of closure and reclamation section, clarification that the freshwater cap depth has not yet been approved and changed the inspection frequency on the FPK discharge location at the LLCF, Beartooth and Panda/Koala FPK pipeline. The broad requirements for the WPKMP are defined in Part H, Item 2 and more detailed requirements are described in Schedule 6, Condition 1 of the Water Licence. The requirements of the Water Licence for the WPKMP are listed in Appendix A along with the location within this Plan where each is addressed. The current Life of Mine Plan is presented in Figure 1. It outlines the currently planned operating timeframes of the various open pit and underground mining activities based on current operating projections, costs and economic factors. The Life of Mine Plan is reviewed on an on-going basis and changes in response to various factors. A current satellite image for the Ekati mine is provided in Figure Limitations Kimberlite is a heterogeneous conglomeration of minerals that causes variability in the wastewater created during mining and processing. This management plan makes assumptions concerning the nature and behavior of the processed kimberlite and the quality and volumes of wastewater that will result from processing kimberlite based on the Ekati mine s processing experience since Ongoing monitoring is required during mine and process operation to verify that the assumptions are correct, and the mine s performance is satisfactory under the terms of its licence. The Wastewater and Processed Kimberlite Management Plan is a guidance document that allows the Ekati mine to adapt to changes in the Life of Mine Plan, processing performance of kimberlite in the plant, and the ongoing characterization of kimberlite being mined. The WPKMP is one of the tools that Dominion uses to meet its legal obligations. It is the commitment Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V

14 of Dominion to not exceed Water Licence discharge criteria and to prevent significant adverse environmental effects in the Receiving Environment downstream that would be caused by the Ekati mine. The methods described in this Plan are based on normal operating conditions. Emergency conditions may require short-term changes while repairs and/or mitigation measures are implemented. During unusually large flow events, the Ekati mine may have to implement short-term measures to protect the safety of the downstream environment and the mining operations. In a case such as this, normal operating practices may be temporarily amended. During emergency situations, the Ekati mine will continue to meet its legal obligations. The Inspector will be informed of any emergency measures being implemented and reasoning for these actions. Dominion will follow up, as soon as possible, with the WLWB by notification of emergency measures undertaken to protect people, property and the environment. 1.3 Changes for Version 9.0 Table 1.2 lists the primary changes to the WPKMP for Version 9.0. Table 1.2 Primary Changes for Version 9.0 Location Change Rationale Section 2.1 and 5.1 Updated Includes Metal and Diamond Mining Effluent Regulations Section , and Updated Updated to reflect the reclamation and closure of the Panda, Koala and Koala North underground mine workings Section Updated Minor update to indicate pipeline from Cell D to Cell E and Reclaim Water Barge water levels Section Updated Clarifies that the freshwater cap depth has not yet been approved Section 5.4 Changed Changed the inspection frequency from twice to once per 12-hour shift for the tailings pipeline and added once per 12-hour shift visual inspection of the Beartooth and Panda/Koala FPK pipelines when active. Section 6 Added Closure and Reclamation Planning Section added as per the Reasons for Decision on WPKMP V Wastewater and Processed Kimberlite Sources Minewater Minewater is defined in the Water Licence as: Minewater includes runoff from facilities associated with the Project and all water or Waste pumped or flowing out of any open pit or underground mine. In this Plan, Minewater is categorized as: Surface Minewater water that flows over or is pumped from surface mine infrastructure including site drainage, truck wash bays, collection sumps, etc.; Open Pit Minewater - water that flows or is pumped from open pits; and Underground Minewater water that flows or is pumped from underground workings. Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V

15 Runoff and seepage from Waste Rock Storage Areas is specifically addressed through the Waste Rock and Ore Storage Management Plan (WROMP). For clarity and to avoid duplication between regulatory documents, runoff and seepage from WRSA s is not addressed herein Sewage Sewage is defined in the Water Licence as: Sewage means all toilet Waste and greywater. Sewage sources are: sanitary sewage system at the main site; and sewage from remote work sites (e.g., Fox Pit, Pigeon Pit Development, Misery Camp) Processed Kimberlite Processed Kimberlite (PK) is defined in the Water Licence as: Processed Kimberlite means material rejected from the process plant after the recoverable diamonds have been extracted. Processed kimberlite generated from processing encompasses two fractions: 1. Coarse Processed Kimberlite (CPK) is the fraction of kimberlite typically greater than 0.5 mm in diameter and is trucked to the southwest area of the Panda/Koala WRSA. 2. Fine processed kimberlite (FPK) is the fraction of kimberlite typically smaller than 0.5 mm in diameter and is transported by pipeline as a slurry to an authorized Processed Kimberlite Containment Area (PKCA), currently the Long Lake Containment Facility, Beartooth Pit, and Panda/Koala/Koala North Open Pits and associated underground workings. In this Plan, management of water that is used within and released from the diamond separation process in the Process Plant is described as part of the management of fine processed kimberlite. Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V

16 2. Management of Minewater 2.1 Overview Minewater must meet the Effluent Quality Criteria (EQC) specified in Part H of the Water Licence and the Metal and Diamond Mining Effluent Regulations (MDMER) on the concentration of deleterious substances, ph and ensure that the effluent is not acutely lethal prior to release to a Receiving Environment. This is achieved by directing Minewater to several centralized Minewater Management Facilities, where the collected waters are analyzed and demonstrated compliant prior to Discharge. The following Minewater Management Facilities are the primary Discharge locations for the Ekati mine, used to manage most of the Ekati mine Minewater: 1. Two Rock Sedimentation Pond (TRSP) at the Sable site manages Discharge to Horseshoe Lake in the Horseshoe watershed. Per Condition H.29 of the Water Licence, the annual volumes of Discharge from Two Rock Sedimentation Pond shall not exceed 740,600 m 3 during the operations phase. 2. Long Lake Containment Facility (LLCF) at the Main Camp site manages Discharge to Leslie Lake in the Koala watershed. Pumping rates do not exceed 2.55 m 3 per second during May to July, inclusive, and 0.52 m 3 per second during the remaining months. 3. King Pond Settling Facility (KPSF) at the Misery site manages Discharge to Cujo Lake in the King-Cujo watershed. Per Condition H.39 of the Water Licence, the annual volumes of Discharge from KPSF may not exceed 470,915 m 3. In future, the (mined-out) Misery Pit will be an operational Minewater management facility to manage Discharge of Minewater from the Jay Project to Lac du Sauvage. Desperation Pond is a named Discharge location in the Water Licence. Desperation Pond is operated as a Minewater sump with all collected water pumped to KPSF. Other incidental uses or releases of Minewater (such as from sumps or for road watering, for example) are conducted under individual authorizations from the Inspector or the WLWB. An overview of the Ekati Main Camp, Misery, Fox, Pigeon, Lynx, and Sable sites, and Jay Project development are provided in Figures 3 to Management of Surface Minewater Management methods for surface Minewater from all current and planned future operations are described below Main Camp and Fuel Storage Berms Surface Minewater is collected from the following locations: Ekati Main Camp and Pit Areas (Figures 10 and 11): snowmelt and rainwater run-off from areas with high vehicular traffic is collected into containment sumps lined with geo-membranes to minimize seepage losses. The collected water is pumped or trucked to the LLCF or otherwise directed to an interim storage location such as Beartooth or Panda/Koala PKCA. Landfarm - water from precipitation (rain/snowmelt): is contained within a plastic liner prior to trucking to the LLCF or an interim storage location such as Beartooth or Panda/Koala PKCA. Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V

17 Contaminated Snow and Ice Containment Facility: Hydrocarbon impacted snow and ice from winter spill remediation activities is collected in this Facility as per the Spill Contingency Plan. The spring melt water is collected in the lined sump and free-phase hydrocarbons are recovered by skimming activities before water is trucked to the LLCF or an interim storage location such as Beartooth or Panda/Koala PKCA. Various Buildings: wastewater collected from various buildings includes wastewater from truck washing operations, maintenance shops wastewater (e.g.; floor washing and general maintenance) that is collected in internal concrete sumps and trucked to the LLCF or an interim storage location such as Beartooth or Panda/Koala PKCA. Scrubbers: The incinerator building is equipped with two wet scrubbers to reduce emissions; collected water is trucked to the LLCF or an interim storage location such as Beartooth or Panda/Koala PKCA. Containment Berms: fuel bulk storage and transfer locations collect rainwater and snowmelt within lined sumps. The spring melt water is collected, and free-phase hydrocarbons are recovered by skimming activities before water is trucked to the LLCF or an interim storage location such as Beartooth or Panda/Koala PKCA. Fresh Air Raise (FARs) Containment Berms: located at the Panda/Koala underground mines produce wastewater that is taken to the LLCF Ammonia Nitrate Storage Facility and Polar Explosives Building The concrete sumps around the Ammonia Nitrate Storage Facility and the Polar Explosives Building collect surface water which is collected by truck and deposited into the LLCF, the Beartooth PKCA or the Panda and Koala PKCA Roads and Laydowns Roads and infrastructure pads are constructed of non-potentially acid generating or low metal leaching potential construction materials as defined in the Waste Rock and Ore Storage Management Plan. Dust suppression measures are applied as appropriate to active haul roads following practices established at the Ekati mine. Runoff from roads, laydowns and the airstrip is attenuated on the tundra or follows natural local flow paths Misery Site The Misery site water management is shown in Figure 12. Runoff from the Waste Rock Dam Pond and Desperation Pond catchments may contain elevated total suspended solids, total metals, and/or ammonia concentrations. The collected Minewater is pumped to KPSF where it mixes with other water prior to release in a controlled manner to the downstream Receiving Environment (Cujo Lake) once Water Licence Discharge criteria has been demonstrated. Runoff from the Misery camp pad flows to KPSF, where it is incorporated into the Minewater management system. A small area of the site facilities pad drains northeast away from KPSF and is attenuated on the tundra or follows natural drainage paths. Management of Minewater collected in KPSF will temporarily be altered during the period of planned underground mining in order to accommodate the anticipated elevated concentrations of total dissolved solids (TDS) in the underground Minewater. Underground, and other, Minewater will be contained in KPSF without Discharge if the Water Licence Discharge criteria cannot be maintained. Non-compliant Minewater will be transferred from KPSF for interim storage in the mined-out Lynx Pit in order to provide a low water level in KPSF at or following the completion of underground mining. Following the completion of underground mining, non-compliant Minewater will be transferred from Lynx Pit to the Misery Pit and underground workings for permanent storage, and normal operation of KPSF will resume. Specific changes in the management of open pit and underground Minewater are described in Sections 2.3 and 2.4. During the Jay Pit operations phase, the Misery Pit will be used to manage both surface Minewater and open pit Minewater from the Jay Pit and diked area. Open pit Minewater (anticipated to contain naturally elevated TDS) will be pumped to near the Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V

18 base of the Misery Pit; surface Minewater will be pumped to the top of the Misery Pit. This will create a TDS gradient in the Misery Pit, resulting in lower TDS concentrations in the upper part of the Misery Pit. Minewater will be contained in the Misery Pit until the water level in the Misery Pit reaches the designated operating range. At this point, compliant Minewater will be pumped from the top of the Misery Pit to Lac du Sauvage for Discharge through a diffuser outfall Fox Site Open pit mining of the Fox kimberlite was completed in 2014 and, since that time, local area runoff (including surface Minewater) enters and accumulates within the pit. During the previous period of open pit mining, most drainage and runoff that flows toward the Fox Pit was captured before it reached the pit by surface diversion ditches and sumps. Once captured, the water was then pumped by a pipeline to Cell C of the LLCF or released to the tundra (with Inspector authorization). An in-line flocculant treatment plant is in place in the LLCF pipeline to be utilized if necessary to aid in settlement of suspended sediment in water pumped to the LLCF. This has not been necessary and has not been utilized since early in Fox pit dewatering activities and remains in place as a contingency only. The operational surface Minewater management pipelines and sumps remain in place pending future consideration of mining the deeper portions of the Fox kimberlite Pigeon Site Surface minewater within the Pigeon Pit area is contained within the water deflection berms located between the northern edge of the Pigeon Pit area and Pigeon Stream and is directed into the surface sumps or managed as Open Pit water. Once captured, the water is moved by pipeline or by truck to the LLCF, Beartooth PKCA or Panda/Koala PKCA (Figure 11) Lynx Site During production at Lynx Pit, surface Minewater within the pit area is directed into surface sumps or treated as Open Pit water (Figure 12). Once captured, water is pumped via dewatering line or trucked to KPSF. Following completion of the Lynx Pit mining activities and during the period of planned underground mining at the Misery kimberlite, Lynx Pit will be used for interim storage of non-compliant minewater pumped from KPSF and the Misery underground workings. Following completion of underground mining, non-compliant minewater will be transferred to the Misery Pit and underground workings for permanent storage Sable Site The Sable Pit site is illustrated on Figure 13. Water entering the pit is collected within a sump in Sable Pit. Collected water in the sump is pumped or trucked out of the pit into upstream portion of Two Rock Sedimentation Pond (TRSP) Jay Site Surface Minewater sources at the Jay site include diked area runoff, including runoff from the Jay WRSA, and Jay Dike seepage (Figure 14). The Jay Dike is designed as a water containment structure with low permeability elements. However, some seepage through the Jay Dike is expected to report to the downstream toe of dike (inside the diked area). This seepage will be collected in ditches and sumps along the dike toe and transferred to the Jay runoff sump to be managed with the surface Minewater. During the Jay Pit operations phase, Jay site surface Minewater will be collected in the Jay runoff sump and pumped to the top of the Misery Pit. The Misery Pit will be used to manage both surface Minewater and open pit Minewater from the Jay Pit and diked area. Open pit Minewater (anticipated to contain naturally elevated TDS) will be pumped to near the base of the Misery Pit; surface Minewater will be pumped to the top of the Misery Pit. This will create a TDS gradient in the Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V

19 Misery Pit, resulting in lower TDS concentrations in the upper part of the Misery Pit. Minewater will be contained in the Misery Pit until the water level in the Misery Pit reaches the designated operating range. At this point, compliant Minewater will be pumped from the top of the Misery Pit to Lac du Sauvage for Discharge through a diffuser outfall. For the duration of the Jay Project, the KPSF will be maintained for possible use as a Minewater contingency measure. 2.3 Management of Open Pit Minewater Panda, Koala North and Koala Pits The lower levels of the Panda, Koala North and Koala open pits are currently hydraulically open to the underlying underground workings (i.e., prior to PK deposition). Once PK deposition commences (scheduled 2019), the pits, including contained Minewater, will be managed as an active PKCA as described in Section 4.8. Excess Minewater that accumulates in the PKCA will be pumped to the LLCF or to the Process Plant on an as-needed basis Fox Pit Open pit mining of the Fox kimberlite was completed in 2014 and, since that time, local area runoff enters and accumulates within the pit. During the previous period of open pit mining, open pit Minewater was pumped by a pipeline to Cell C of the LLCF. An in-line flocculant treatment plant is in place in the LLCF pipeline to be utilized if necessary to aid in settlement of suspended sediment in water pumped to the LLCF. This has not been necessary and has not been utilized since early in Fox pit dewatering activities and remains in place as a contingency only. The operational Minewater management pipelines remain in place pending future consideration of mining the deeper portions of the Fox kimberlite Misery Pit While open pit mining activities are underway, sumps located in the Misery Pit collect water, which is pumped to KPSF (Figure 12). While planned underground mining activities are underway following completion of open pit mining, open pit Minewater will mix with and be managed as underground Minewater (see Section 2.4.2). During the Jay Pit operations phase, the Misery Pit will be used to manage both surface Minewater and open pit Minewater from the Jay Pit and diked area. Open pit Minewater (anticipated to contain naturally elevated TDS) will be pumped to near the base of the Misery Pit; surface Minewater will be pumped to the top of the Misery Pit. This will create a TDS gradient in the Misery Pit, resulting in lower TDS concentrations in the upper part of the Misery Pit. Minewater will be contained in the Misery Pit until the water level in the Misery Pit reaches the designated operating range. At this point, compliant Minewater will be pumped from the top of the Misery Pit to Lac du Sauvage for Discharge through a diffuser outfall Beartooth Pit Prior to 2009, water was pumped or trucked out of the Beartooth Pit to the LLCF. Mining operations ceased in 2009 and, since that time, the Beartooth pit has been used for retention of Minewater that was enriched in nitrate and/or chloride. This was initiated as an adaptive management response to enhance the protection of the environment downstream of the LLCF. Underground Minewater, surface Minewater from the Ammonium Nitrate storage facility sumps, and other Minewater has been directed to the Beartooth Pit since This practice will continue on an adaptive management basis as needed. Use of the Beartooth Pit as a PKCA was approved by the WLWB in 2012 and since that time FPK has been deposited into Beartooth PKCA via slurry pipeline on an intermittent basis. Excess Minewater that accumulates in the PKCA is pumped to the LLCF or the Panda Pit, on an as-needed basis, typically seasonally during the summer season. Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V

20 2.3.5 Pigeon Pit Open pit Minewater from Pigeon Pit is moved by truck to the LLCF, Beartooth PKCA or Panda/Koala PKCA (Figure 11) Lynx Pit Open pit Minewater from Lynx Pit is collected in the pit and moved by pipeline or truck to KPSF (Figure 12). Following completion of the Lynx Pit open pit mining activities and during the period of planned underground mining at the Misery kimberlite, Lynx pit will be used for interim storage of non-compliant Minewater pumped from KPSF and the Misery underground workings. Following completion of underground mining, non-compliant Minewater will be transferred to the Misery Pit and underground workings for permanent storage Sable Pit Open pit Minewater from Sable Pit is collected in the pit and moved by pipeline or truck to the upstream cell of Two Rock (Figure 13) Sedimentation Pond where suspended sediments settle and filter from the water that seeps through the filter dyke to the downstream cell. The sediment capacity of TRSP is anticipated to be adequate for the duration of the open pit operations without interim excavation. The functioning of TRSP is monitored during operations (Section 5.7) and excess sediment in the upstream cell may be excavated if necessary to ensure effective settling of sediment Jay Pit Open pit Minewater sources include runoff over pit walls and groundwater inflows (Figure 14). During the Jay Pit operations phase, Jay open pit Minewater will be collected at the bottom of the Jay Pit and pumped to the mine inflows sump located in a natural depression within the diked area of the Lac du Sauvage lakebed; also, near the crest of the Jay Pit. It is anticipated that there will be elevated TDS in the water from groundwater inflows to the Jay open pit, thus this water will be pumped from the mine inflow sump to near the base of Misery Pit. The Misery Pit will be used to manage both surface Minewater and open pit Minewater from the Jay Pit and diked area. Open pit Minewater (anticipated to contain naturally elevated TDS) will be pumped to near the base of the Misery Pit; surface Minewater will be pumped to the top of the Misery Pit. This will create a TDS gradient in the Misery Pit, resulting in lower TDS concentrations in the upper part of the Misery Pit. Minewater will be contained in the Misery Pit until the water level in the Misery Pit reaches the designated operating range. At this point, compliant Minewater will be pumped from the top of the Misery Pit to Lac du Sauvage for Discharge through a diffuser outfall. For the duration of the Jay Project, the KPSF will be maintained for possible use as a Minewater contingency measure. 2.4 Management of Underground Minewater Panda/Koala/Koala North Workings The Panda, Koala and Koala North Mine workings have been reclaimed and closed in February Deposition of FPK in the Panda, Koala and Koala North open pits and mine workings has been approved in WPKMP V8.0 and is planned to start in Misery Workings Underground mining of the deeper portions of the Misery kimberlite is planned following completion of open pit mining activities and prior to commencement of the planned Jay project dewatering of the diked area of Lac du Sauvage. Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V

21 Underground Minewater will be pumped to KPSF or to Lynx pit in accordance with Water Licence Condition H.29. Elevated concentrations of TDS in the Misery underground Minewater is anticipated to result in non-compliant concentrations in KPSF at some time during underground mining activities, at which point Discharge from KPSF will not take place and Minewater will be retained. Non-compliant Minewater that has been retained in KPSF and remaining underground Minewater will be transferred for interim storage in the mined-out Lynx Pit. If the water level in KPSF approaches operating maximum and Discharge is not possible, contingency actions would be considered and implemented, which would include the following: using storage capacity available at the Ekati main site; discontinuing Lynx Pit mining (i.e., finish mining Lynx Pit earlier so that it is available as a water management facility); and discontinuing pumping of underground Minewater to KPSF. Following the completion of underground mining, non-compliant Minewater will be transferred from Lynx Pit to the Misery Pit and underground workings for permanent storage. Should water quality in KPSF not be suitable for Discharge to Cujo Lake immediately following Misery Underground Project operations, pumping from KPSF to Misery Pit will continue until water quality meets Discharge criteria. Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V

22 3. Management of Sewage An enclosed sanitary sewage treatment plant to treat all domestic wastewater was installed at the Ekati mine main camp as part of the original site infrastructure construction in The sewage treatment system has both primary and secondary levels of treatment. The final treated effluent is pumped through an insulated and heat-traced pipeline to the Process Plant where it is mixed with the FPK before being discharged to an approved PKCA (Figure 15). Solid sewage waste is deposited in Zone S of the Panda/Koala WRSA. During upset conditions with the sewage treatment plant, raw sewage may be discharged directly to an approved PKCA for short periods of time after notification to the Inspector. Sewage collected from the underground operations surface buildings and from the underground workings is trucked to the main camp sewage treatment facility. Sewage generated at remote washroom facilities (e.g.; Fox Pit, Misery Camp, Pigeon Pit, Lynx Pit, Sable Pit, and Jay Pit when in operation) is trucked to the main camp sewage treatment facility. Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V

23 4. Management of Processed Kimberlite 4.1 Diamond Separation Process A description of the Process Plant operations is contained in Appendix B and provides information on the diamond recovery process. The diamond recovery process involves three basic steps: 1. Size reduction, washing (scrubbing), and screening; 2. Primary concentration; and 3. Secondary concentration Size Reduction, Washing (Scrubbing), and Screening Size reduction involves crushing the kimberlite ore into smaller sized particles to mechanically liberate the diamonds. In this stage of the process, water is used to wash and screen the crushed ore, and to transport the processed ore (i.e.; processed kimberlite). Waste occurs as: Wastewater; Coarse Processed Kimberlite (0.5 to 1.2 mm fraction); and Fine Processed Kimberlite (< 0.5 mm fraction). Water is either recycled within the Process Plant or is pumped as FPK slurry to an approved PKCA. Water is recovered from the LLCF for use in the Process Plant. The coarse rejects are trucked to the designated area of the Panda/Koala WRSA, per the WLWB-approved WROMP Primary Concentration This is the first stage of the process that separates the diamonds from the kimberlite ore. Primary concentration involves using Heavy Medium Separation to concentrate the diamonds by physically separating material based on density. Water and Ferrosilicon is used in this process as the separation medium (Ferrosilicon is recycled based on its magnetic properties). The low-density material is screened, and the solids are generally routed to the coarse rejects waste stream and trucked to the WRSA. The high-density material contains the diamonds and it is rinsed to remove the ferrosilicon and then progresses to the secondary concentration. Wastewater is treated to recover ferrosilicon and water for recycling within the Process Plant Secondary Concentration The secondary concentration process consists of sorting the material containing the diamonds by magnetism and X-rays. The final stage of separation involves hand-sorting by personnel. The waste streams from this process are water and coarse rejects that are trucked to the designated area of the Panda/Koala WRSA, per the WLWB-approved WROMP. Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V

24 4.1.4 Flocculants Flocculants are added in the Process Plant to enhance the settlement of FPK in the Process Plant thickeners and to some extent in the approved PKCAs. The use of flocculant is part of the routine Process Plant procedures. Calcium chloride addition is also approved and is sometimes necessary to facilitate the settlement of fines when ore is processed containing higher clay contents. 4.2 Process Water Figure 15 presents the Ekati water and liquid waste summary. Water used in the Process Plant is either recycled from within the Process Plant or pumped to an approved PKCA as FPK slurry water, which is then available to be reused. 4.3 Processed Kimberlite Figure 16 presents information on the Ekati solid waste summary. Processed Kimberlite (PK) is produced as two waste streams differentiated by grain size, Fine Processed Kimberlite (FPK) with grain size generally less than 0.5 mm and Coarse Processed Kimberlite (CPK, also called coarse rejects) with grain size generally greater than 0.5 mm. PK is deposited in an approved Processed Kimberlite Containment Area (PKCA). The Water Licence provides definitions for CPK, FPK, PK and PKCA as follows: "Coarse Processed Kimberlite means coarse material, as defined in the approved Wastewater and Processed Kimberlite Management Plan, rejected from the Process Plant after the recoverable diamonds have been extracted. Fine Processed Kimberlite means fine material, as defined in the approved Wastewater and Processed Kimberlite Management Plan, rejected from the Process Plant after the recoverable diamonds have been extracted. "Processed Kimberlite means material rejected from the Process Plant after the recoverable diamonds have been extracted. Processed Kimberlite Containment Area means those locations at which the Licensee may deposit Processed Kimberlite, as approved by the Board. CPK is trucked to the designated area of the Panda /Koala/Beartooth WRSA and is managed under the Waste Rock and Ore Storage Management Plan. CPK is not described further herein. FPK is pumped as a slurry to one of the following approved PKCAs: LLCF, Beartooth Pit or Panda/Koala/Koala North Open Pits and associated underground workings (Panda/Koala PKCA). PK quantities and deposition locations are recorded and reported annually in the Water Licence Annual Report. 4.4 FPK Physical Properties FPK is generated from washing and screening of the ore and from the Heavy Medium Separation of the ore. The FPK is de-watered or thickened in the Process Plant to recover process water for recycling within the plant. The FPK slurry contains coagulants and flocculants, which are used to recycle the process water (Section 4.5). In some cases, saline water or calcium chloride is added to assist with the settling of fines (extraction of water to 40% solids); after which the remaining slurry is pumped to an approved PKCA. Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V

25 Within the FPK there is a fraction of material referred to as Extra Fine Processed Kimberlite (EFPK). The material has a high silt and clay content (< 0.1 mm) and remains in suspension longer than FPK. EFPK has different physical properties from FPK (described below). In the LLCF, the coarser size fraction of FPK (mainly sand sized particles) settles out first to form well-defined sub-aerial and sub-aqueous beaches. This phase accounts for approximately 88 percent by mass of the FPK Discharge and has typically exhibited the following physical characteristics when placed in the LLCF: A void ratio of approximately 1.7, which can include up to 15 percent excess ice that is trapped and frozen in the deposit before the water can drain away. This results in an average dry density of 1.05 t/m 3. Efforts are made to rotate FPK deposition between spigots through the winter season to avoid excessive ice entrainment, since the ice otherwise utilizes FPK storage capacity. Measured sub-aerial beach gradients ranging from 1.1 percent to 2.7 percent and averaging approximately 1.8 percent. Sub-aqueous beach gradient ranging from 4.2 percent to 22 percent and averaging approximately 9 percent. The finer size-fraction of FPK (i.e., EFPK, mainly silt and clay sized particles) takes longer to settle when deposited in the LLCF due to its finer grain size. It has been observed that EFPK that does not settle on LLCF beaches is carried into the nearest pond, where it settles at the base of the pond. Flocculant and coagulants are added in the Process Plant to facilitate the settling of fine particles and to increase overall FPK settling rates. This approach ensures that water can be recycled internally in the Process Plant and lowers the amount of reclaim water required in the diamond process. Control room operators vary the amount of flocculant and coagulant added depending on the actual settling characteristics of the kimberlite ore being fed to the plant. The process of coagulation involves the aggregation of typically very fine charged clay particles that on their own have very low settling rates. Through the addition of flocculant, these aggregates can combine with other FPK to form flocs, larger structures that have higher settling rates and facilitate the recycling of water in the Process Plant. Cone Penetration Testing (CPT) was conducted in October 2010 to investigate the materials in Cell C, including the extra-fine processed kimberlite (RGC 2011). The testing consisted of 13 Cone Penetration Test Soundings, 6 Ball Penetration Tests, 1 Vane sounding and 4 soil sample locations. The results found clear water to a depth of about 5 m overlying a soft to firm (7.5 kpa) silt/clay layer, which is interpreted to be EFPK. This layer may have formed during winter as a result of elevated salinity (chloride) in the pore water and relatively low winter water levels. The CPT data indicated little EFPK in the upper 5 m of the water column in Cell C. This may be the result of chemistry changes (increased salinity) in the pool combined with the physical effects of ice formation under relatively low winter water levels. Specifically, the temperatures measured in the upper 5 m fluid during the CPT are generally less than zero C, averaging between -2 and -3 C. The elevated salt content may have depressed the freezing point which, combined with lower winter water levels in Cell C in recent years, has enabled enhanced settlement of the EFPK. The long-term consolidation and physical characteristics of FPK deposited into Beartooth and Panda/Koala PKCA has been numerically modelled (see Golder 2018). The modelling efforts were based on laboratory testing of FPK samples obtained from the Process Plant and operational monitoring of bathymetric surveys (2017 Annual Progress Report) and quantities of FPK solids deposited into Beartooth Pit reported in annual Water Licence Reports. Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V

26 4.5 Kimberlite Geochemical Characterization All the kimberlite handled at the Ekati mine (i.e., coarse PK, FPK and kimberlite waste rock) shares the same geochemical characteristics and is all classified as non-potentially acid generating due to its high carbonate content and low sulphur content. The Ekati mine geochemical dataset was compiled according to rock type for Jay Project Developers Assessment Report (DDEC 2014, Annex VIII, Geochemistry Baseline Report). The dataset included 360 samples of kimberlite collected from the Beartooth, Misery, Pigeon, Sable, Fox, and Koala areas, and 2 samples from the Jay pipe. In addition, 189 samples of coarse PK and 39 samples of fine PK were submitted for geochemical testing. The dataset included pre-development samples and operational monitoring samples (to 2013). Analysis of the dataset confirmed previous interpretations that kimberlite is non-pag owing to the abundance of carbonate minerals in these materials. The key conclusions from analysis of the ABA results were: Kimberlite had paste ph values ranging from 5.1 to 10. Total sulphur concentrations ranged from % to 1.9%, with a median concentration of 0.26%. Generally, the highest total sulphur concentrations were observed in kimberlite samples collected from the Misery Pit and the Panda Pit, and the lowest sulphur concentrations were observed in samples from the Pigeon area. Sulphur is primarily in the form of sulphide in the kimberlite samples. The AP of the kimberlite samples ranged from 0.08 to 61 kg CaCO3 /tonne. The highest AP values were reported in samples from the Misery and Panda pits with the highest sulphide-sulphur concentrations. The NP of the kimberlite samples ranged from 2.5 to 465 kg CaCO3 /tonne and the CaNP ranged from 1.1 to 187 kg CaCO3 /tonne. Kimberlite samples reported a large variation in the NP to CaNP ratio. On average, NP was four times greater than CaNP. A total of 188 kimberlite samples were analyzed for NP and AP, of which 184 samples (98%) had NP/AP ratios greater than 2 (see Table in DDEC 2014, Annex VIII, Geochemistry Baseline Report). Kimberlite is classified as non PAG.A total of 188 kimberlite samples were analyzed for NP and AP, of which 184 samples (98%) had NP/AP ratios greater than 2. Kimberlite is classified as non-pag. The results of bulk metal analysis of 234 kimberlite samples identified that parameters that occurred at concentrations greater than five times the average crustal abundance in more than 10% of the kimberlite samples include bismuth, magnesium, nickel, and antimony. Certain samples also had elevated concentrations of chromium, mercury, strontium, and tungsten. Fewer samples had elevated concentrations of silver, arsenic, barium, molybdenum, phosphorus, lead, thorium, and tungsten. Nine kimberlite samples were submitted for kinetic testing. Test length ranged from 41 to 130 weeks. All nine kimberlite samples were classified as non-pag based on ABA results and depletion calculations. These samples also had stable and neutral ph values in the humidity cells. The HCT results for kimberlite were summarized as follows: ph values were near-neutral to alkaline and ranged from 7.5 to 9.6. The ph values were generally stable over time in all samples. Sulphate concentrations decreased after the first flush in all samples, and stabilized to below 100 mg/l. Aluminum concentrations ranged from below to 0.50 mg/l. There was generally no trend in aluminum concentrations over time consistent for all samples. Most samples reported stable aluminum concentrations. Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V

27 Arsenic concentrations typically ranged from to 0.02 mg/l. Copper concentrations ranged from to 0.04 mg/l and were less than 0.03 mg/l in all but two leachate samples. Iron concentrations ranged from to 0.59 mg/l, except for two peaks reported in the leachates from a kimberlite from the Misery Pit. Nickel concentrations ranged from to 0.12 mg/l. Nickel concentrations generally decreased and stabilized after the first flush. Potassium concentrations ranged from 1.0 to 310 mg/l. Concentrations generally stabilized below 30 mg/l at steady-state conditions. Molybdenum concentrations ranged from to 1.6 mg/l. Vanadium concentrations ranged from to 0.18 mg/l. Phosphorus concentrations ranged from less than 0.10 to 0.70 mg/l, and generally stabilized to below the detection limit (0.10 mg/l) after the first 10 weeks of testing. Cobalt concentrations ranged from below to mg/l. Generally, cobalt concentrations were stable after 20 weeks of testing. Kimberlite waste rock has not been mined since compilation of the 2014 dataset and, therefore, no further test results are available. Operational monitoring of coarse PK is undertaken on a quarterly basis (or as otherwise specified in the WROMP) and includes acid-base accounting analyses. The results are reported annually and the most recent report, based on 2017 data, reported that the CKR material stored in the CKRSA has sufficient carbonate NP to neutralize any acid generation from sulphide oxidation (as indicated by the long-term median of carbonate NP/MPA of 6.2) (SRK 2018). Prior to mining at the Ekati mine, re-circulating leach column tests were completed on two samples of simulated Fine Processed Kimberlite (FPK), one from the Panda Pipe and one from the Fox Pipe. Acid base accounting data for the samples indicated the Panda Pipe sample had a ph of 8.4 and a total sulphur content of 0.33%. The Fox Pipe was considerably more alkaline (ph of 9.9) and contained less sulphur (0.12%). Both samples contained high neutralization potentials (491 and 335 kg CaCO3/t, respectively) and were classified as non-acid generating. Eight weeks of FPK column leaching data were carried out and the Panda FPK sample displayed results similar to those observed for the Panda coarse reject sample. The ph remained stable between 7 and 8 and the general trend for release of metals was an initially rapid increase followed by erratic concentrations without an apparent increasing or decreasing trend. ABA data and metal analysis results are available for Fine Processed Kimberlite (FPK) samples collected in 2004 and The FPK solids had total sulphur concentrations ranging between 0.10% and 0.58%, with an average of 0.28%. Average Sobek NP values were 311 kg CaCO3/t resulting in high average Sobek NP/MPA ratios (average of 36). These results were similar to those of kimberlite ore and suggested that there was sufficient neutralization potential within the FPK to neutralize acid produced as a result of oxidation of contained sulphides. The FPK solids contained elevated concentrations of chromium, cobalt and nickel, typical of kimberlite material. Trace metal concentrations are within the range of concentrations observed for Koala kimberlite and Fox waste kimberlite. 4.6 Long Lake Containment Facility PKCA Facility Description The Long Lake Containment Facility encompasses Long Lake and the former headwater lakes of Long Lake (Figure 17). The LLCF is at the headwater of the western Koala Watershed which feeds into the Lac de Gras watershed. Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V

28 The LLCF currently includes the following components: Cells A, B, C, D, and E. Cells A and C of the LLCF will continue to be available as active FPK deposition locations until they reach their final designed capacity limits. Cell B is no longer receiving FPK. Cell D is licensed to store PK, but no deposition has occurred to date; instead, Cell D is used as a minewater management and reclaim water pond. Cell D will serve as a contingency PK deposition area throughout mine operations. Cell E provides surge water storage capacity for surplus water and acts as a finishing pond prior to pumped Discharge to the Receiving Environment. Cell E will not receive FPK. Dikes B, C, and D (designation corresponds to upstream subtended cell). These filter dikes are designed to retain PK solids within the upstream cell but allow water to filter through to the downstream cell. Dike B is considered to be effectively sealed (as anticipated) and water transfer from Cell B to C flows through a culvert. Dike C is considered to be partially sealed and water transfer from Cell C to D is augmented by pumping. Dike D is not affected by PK but water transfer from Cell D to E is augmented by pumping as required to safely manage pond water levels. Dams The Outlet Dam serves as the downstream water control structure at the outlet of Cell E which retains water until sampled, authorized and pumped to the Receiving Environment. Water levels are maintained with minimum 1.0 m freeboard and in accordance with the current Water Licence. Water Pumps Pumps on the upstream side of Dike C are used to pump water from Cell C to the reclaim barge in Cell D. The reclaim water barge in Cell D pumps water to the processing plant. In 2017, a weir was installed on Dike D to control the flow of water from Cell D to Cell E (this has replaced a previously installed diesel-powered pump). Pumps in Cell E transfer water that meets the current Water Licence (W2012L2-0001) effluent quality criteria into Leslie Lake (at SNP Station ). Pumping rates into Leslie Lake are up to 2.55 m 3 /s from 1 May to 31 July, and 0.52 m 3 per second at other times (approximately 6 to 8 million m 3 annually). Access Roads Roads are located along the north side of Cell A, around the perimeter of Cell B; along the east, west, and south sides of Cell C; and along the east side of Cells D and E. The Fox Pit road extends from the processing plant to the outlet dam across the Outlet Dam. Powerlines, Pipelines, and Discharge Spigots Pipelines are used for the delivery of the FPK slurry along the access roads from the Process Plant site. These run along the east, west, and north side of Cell C, and the north side of Cell A (Figure 17). Electric pumps are used to pump the water from Cell E to Leslie to reduce environmental risks associated with diesel pumps Water Management Operationally the Ekati mine typically manages the water elevations in the LLCF to allow for storage volumes for spring freshet or rain events. The levels of water in these cells is monitored and water is pumped as required to maintain the necessary freeboard; especially during spring freshet conditions or rain events. As required by the Water Licence the maximum water elevations in the LLCF Cells are dictated by recommended freeboard limits set by the dike design professional engineers. Filter dike B has become sealed by FPK and little water filters through the dike from Cell B into Cell C. An overflow spillway has been installed for passive transfer of water from Cell B into Cell C. Intermediate Dike C is a zoned rock fill structure with the purpose to retain processed kimberlite in Cell C, while allowing water to drain from Cell C to Cell D. The dike has been raised in stages since its initial construction with a current nominal crest elevation of 459 masl. The water level in Cell C is required to be maintained below to ensure containment of FPK solids and Minewater within the current Cell C road boundaries. Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V

29 A Reclaim Water Barge is located at the north end of the cell, which pumps water from Cell D to the Process Plant (Figure 18). The reclaim barge is located in Cell D to provide adequate quality (i.e., clarity) and quantity of water (about 4.5 M m 3 annually) for diamond processing. Water is syphoned or pumped from Cell C to the intake of the reclaim barge. In order to contain water within the LLCF watershed the maximum level in Cell D has been set to m. Pipes have been installed to convey water from Cell D to Cell E. Pumps located on Dike D pump water over the dike into Cell E to augment dike seepage when desired to manage Discharge from Cell E or to maintain desired water levels in Cell D. The Reclaim Water Barge has been designed such that ideal water level in Cell D is 448 and the minimum water level should be 447 m. The crest elevation of the Outlet Dam is m for the frozen core element of the structure and the top of rock is m. Outlet Dam ensures water does not exit from the LLCF into the Receiving Environment until the water is sampled and proven to meet Discharge criteria. When the water has been demonstrated to meet Discharge requirements, it is pumped to Leslie Lake. Pumping rates are up to 2.55 m 3 per second from 1 May to 31 July, and 0.52 m 3 per second at other times. The water level is generally maintained less than or equal to Cell D with a maximum level of m 4.7 Beartooth PKCA Facility Description Beartooth Pit is a relatively smaller sized open pit located approximately 3 km from the Process Plant to the north of and adjacent to Panda Pit. Mining operations in Beartooth Pit ceased permanently in Since 2009, the mined-out pit has been used as a Minewater retention pond at times when it is beneficial to divert certain waste water sources away from the LLCF. This was approved by the WLWB in April Use of the Beartooth Pit as a PKCA was approved by the WLWB in 2012 through Version 3.0 of the WPKMP. FPK has been deposited into Beartooth Pit via slurry pipeline on an intermittent basis since February Deposition of FPK into the pit from the end of the pipe and pumping out of Beartooth are shown on Figure 19 and 20, respectively. In accordance with WLWB approvals, FPK is planned to be deposited to the WLWB-approved elevation 30 m below the final (closure) overflow elevation. Dominion may conduct further studies to optimize the depth of freshwater cap required for closure. Any proposed design revision would be submitted to the WLWB for approval prior to implementation. In accordance with WLWB approvals, operational monitoring of FPK deposition into Beartooth PKCA has been applied to planning for FPK deposition into the Panda/Koala PKCA (scheduled to commence in 2019) Water Management Beginning in 2009, various sources of Minewater have been directed to the mined-out Beartooth Pit (subsequently Beartooth PKCA) including from the Ammonium Nitrate (AN) Storage Facility sumps, Polar Explosives sump and underground Minewater from Panda and Koala. The diversion of this water away from the LLCF was initially part of Dominion s adaptive management response to elevated nitrate concentrations in the LLCF water and to the risk of future elevated chloride concentrations in the LLCF water. These measures continue to be used to reduce potential effects in the Receiving Environment downstream of the LLCF. The in-pit water elevation is maintained at least 1 m below overflow by pumping. Excess Minewater, precipitation and runoff that accumulates in the pit is pumped to the LLCF (Cell C) on an as-needed basis, typically seasonally during the summer season. The pumped water mixes with other waters in the LLCF and forms part of the Discharge from Cell E of the LLCF to the Receiving Environment, Leslie Lake. Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V

30 4.8 Panda/Koala PKCA Facility Description Open-pit mining at the Panda Pit commenced in 1998 and was completed in Underground development and production in the Panda underground workings began in 2005 and was completed in 2010 after which the underground workings were decommissioned for closure. Waste rock removal for Koala Pit and at the Koala North Pit commenced in 2000 and was completed in The Koala Underground operation began in 2004, with kimberlite production beginning in Underground development and production in the Koala North underground workings began 2009 and was completed in 2015 after which the underground workings were decommissioned for closure. Open-pit mining at the Koala Pit commenced in 2003 and was completed in Underground development and production in the Koala underground workings began in 2007 and is scheduled for completion in 2018/2019. Decommissioning of the Koala underground workings is undertaken progressively as individual mining areas are completed and is scheduled to be fully completed in The mined-out Panda, Koala and Koala North Pits (and associated underground workings) represent large, secure, long-term waste storage areas that have previously been identified as potential PK deposition locations following completion of underground mining in the Koala kimberlite pipe, especially in the case of a substantive extension of mine life such as the Jay Project. The underground workings are interconnected such that FPK cannot be deposited into any of these open pits while underground operations are ongoing in the Koala kimberlite. The Panda/Koala PKCA was approved as a PKCA for FPK deposition through the 2017 Jay Project Water Licence Amendment, with requirements for follow-up planning studies, which are incorporated herein in support of the commencement of FPK deposition in Once available and authorized for commencement of FPK deposition, the Panda/Koala PKCA will become the primary FPK deposition location, with secondary deposition into the Beartooth and LLCF PKCAs. Planning for FPK deposition into the Panda/Koala PKCA is based, in part, on operating experience and monitoring data gained from deposition into the Beartooth PKCA. This includes providing input into modelling of FPK physical and consolidation characteristics, and PKCA water quality. Consistent with the Beartooth PKCA, and based on water quality predictive modelling for the Panda/Koala PKCA developed by Golder Associates (Golder 2018), Dominion proposed in WPKMP V.8.0 that the depth of a water cap for closure is unlikely to be greater than 30 m. Dominion proposed in WPKMP V.8.0 to provide the results of a reclamation research study that would finalize/optimize the depth of a water cap for closure of the Panda/Koala PKCA prior to the in-pit elevation of FPK reaching 50 m below final overflow (i.e., conservatively prior to FPK reaching 30 m below overflow). In its approval of WPMP V.8.0, the WLWB directed that the final water cap depth and the required submission date for the related reclamation research study be determined through review of ICRP V.3.0 (which was concurrent to submission/approval of WPKMP V.8.0). Therefore, the closure water cap depth for the Panda/Koala PKCA has not been approved. Similar to FPK deposition into Beartooth PKCA, deposition into Panda/Koala PKCA will be through slurry pipelines to the crest of each pit (Panda, Koala and Koala North). The pipelines will be sized to pass the entire slurry volume from the Process Plant Water Management Once activated, the Panda/Koala PKCA will receive various sources of Minewater that may have previously been directed to the Beartooth PKCA. This may be done to enhance short-term water quality in the LLCF and Beartooth PKCAs, or as a matter of operational convenience (i.e., local area sumps). The water elevation within the Koala pit component of the Panda/Koala PKCA (i.e., the location where Minewater could overflow to the Receiving Environment) will be maintained at least 2 m below overflow by pumping excess Minewater to the LLCF or to the Process Plant as recycle process water. Pumping will be conducted on an as-needed basis beginning several years after commencement of FPK deposition once the in-pit water elevation has reached a practical pumping elevation that Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V

31 allows safe access. The start of pumping is currently planned for 2027 or 2028 (ERM 2017). The pumped water will mix with other waters in the LLCF and form part of the Discharge from Cell E of the LLCF to the Receiving Environment, Leslie Lake. Updated water quality modelling for the operations timeframe confirms that water quality in the LLCF will meet Water Licence Discharge criteria and may be improved through FPK deposition into the Panda/Koala PKCA (ERM 2017). 4.9 Fine Processed Kimberlite Deposition Plan Background Prior to commencement of FPK deposition into Beartooth PKCA in 2013, all the FPK produced throughout the mine life (beginning in 1998) had been deposited into the LLCF, apart from a relatively small amount of test and start-up FPK deposited into the Phase 1 Containment Area (closed in 1998). The Phase 1 PKCA was reclaimed from 2014 to 2017 and PK was disposed to the LLCF (see DDEC 2013). The initial operating approach for the LLCF was reviewed and refined through a consultative process that was undertaken in 2004 and The objectives of the review were to: Categorize the FPK deposit that had developed in the LLCF as a consequence of the depositional plan and review management practices implemented to date. Identify opportunities for the optimization of the LLCF management system which would improve operational costs, reliability, and mitigate potential operational and closure environmental effects. Alternative operation and development options were presented to Ekati mine stakeholders during a series of three meetings in 2004 and early 2005 (BHP Billiton 2005). The meetings were attended by Ekati staff, consultants, regulators, Aboriginal Affairs and Northern Development Canada (now Indigenous and Northern Affairs Canada), Environment Canada (now Environment and Climate Change Canada), Government of Northwest Territories (GNWT), Aboriginal community representatives, and Independent Environmental Monitoring Agency (IEMA) participants. At that time, several operating strategies were assessed, and a collectively preferred approach was identified with the following objectives, which remain in effect: Maximize use of the available storage capacity in volume in Cells A, B, and C to minimize the overall footprint of the stored FPK deposit, considering the geometry of beaching and the need to store EFPK. Delay deposition of FPK to Cell D for as long as possible. Develop an FPK delivery and discharge system that is simple and robust for winter operating conditions and which minimizes ice entrainment. Create landforms with stable topography suitable for reclamation. Optimize diversion facilities, where feasible, to preclude concentrated flow from external catchment areas flowing onto the beaches. Establish internal ponds to limit erosion of the EFPK and provide settling. Minimize the potential need to construct additional perimeter dams, such as East Dam and Spillway Dam, by raising Cell C and constructing diversion ditches, and thereby minimize the need for long-term monitoring and maintenance of such structures. Provide for water management of flow through the LLCF over the long term, recognizing that EFPK will accumulate and will continue to restrict flow through the dikes. Provide flexibility for managing future water quality within the operational, closure, and post-closure phases. Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V

32 Implementation of the preferred approach included the following construction activities: In 2007 the Cell B west access road was constructed along the west slope above Cell B. This west access road and pipeline allowed renewed deposition into Cell B from west to east using the high ridge that bounds Cell B to elevate the spigot points. This approach increased the volume of FPK that would be stored in Cell B. In 2008/09 the access road on the north slope of Cell A was relocated upslope from its previous elevation to a higher elevation. This provided a higher platform for the Discharge spigots. This location incorporates most of the area of the catchment on the north side of the impoundment and increases the volume of FPK that can be placed in Cell A. The previous access road at the lower elevation will be covered by the new beach that forms on the slope below the new road. In 2010 the Cell C dike was raised to 459 masl. Spigots were installed with valves allowing Discharge to be directed from any spigot simply by opening or closing the appropriate valves. The valve system was installed and protected from the weather to allow yeararound independent operation of the spigots with the capability to alternate flows in accordance with the deposition plans. In 2011, the LLCF deposition plan was further optimized through an evaluation of options presented in the report titled Ekati Mine 2011 FPK Deposition Alternative Study (BHP Billiton 2011b). The 2011 optimization demonstrated the beneficial use of Beartooth Pit and, possibly, Cell C West and Cell A South for FPK deposition and remains the plan being implemented until FPK deposition into the Panda/Koala pits is established. The selected sequence of options initiated in 2011 is summarized in Table 4.1. Table 4.1 Fine Processed Kimberlite Volumes Associated with Deposition Options Option Description Continue in Cell A North, Cell B West, and Cell C North (FPK deposition in Cell B has subsequently been completed) Volume 15 Mm 3 Beartooth Pit (secondary FPK stream) 7 Mm 3 Cell C West 6 Mm 3 Cell A South 4 Mm 3 Cell C East 2 Mm 3 TOTAL 34 Mm 3 Cell D as Contingency FPK = fine processed kimberlite; Mm 3 = million cubic metres. Implementation of the 2011 optimization has included construction of the Cell C West road, the slurry pipeline to Beartooth PKCA and the water pumping system in Beartooth PKCA. Future construction, if necessary, could include construction of the Cell A South road and raising of Dike C. The future construction elements are currently not considered necessary provided the Panda/Koala PKCA is available for FPK deposition in 2019 as planned. The 2011 optimization study identified the Panda and Koala Pits as a preferred PKCA once mining in the Koala underground workings was complete and particularly if a substantive extension of mine life was implemented. Environmental assessment and licencing for the Jay Project was completed in 2017 (W2012L (Amendment to incorporate Ekati Jay Project)), which plans to extend the mine life substantially, by 10 years or more. Assessment and Licencing of the Jay Project included approval of the Panda, Koala and Koala North Pits and associated underground workings as a PKCA. Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V

33 Mining in the Koala underground workings was completed in 2018 and the reclamation and closure of Panda / Koala underground workings in February FPK deposition into the Panda/Koala PKCA is planned to commence in Deposition Plan The FPK Deposition Plan is as follows: 1. Continue current operating procedures for FPK deposition into the LLCF (primary) and Beartooth (secondary) PKCAs. 2. Complete construction of slurry pipelines to the three pits of the PKCA (Panda, Koala and Koala North) sized to pass 100% of the slurry stream; 3. Utilize the Panda/Koala PKCA, when available, for primary FPK deposition and the Beartooth and LLCF PKCAs for secondary deposition. 4. Deposit FPK into Cell D of the LLCF PKCA only on an emergency basis and with notification to the WLWB; Cell D provides an essential back-up measure that prevents mine shutdown if a line blockage or breakage occurs between the processing plant and the primary/secondary deposition locations, or other reasons. 5. Continue current procedures for pumping water from Cell D of the LLCF PKCA to the Process Plant for use as recycle process water. 6. Start procedures for pumping excess water from Beartooth PKCA to the Panda PKCA. 7. Once the water level in the Panda/Koala PKCA reaches a practical pumping elevation (i.e., high enough for safe access and efficient pumping), manage the Panda / Koala PKCA water elevation below freeboard requirements by pumping to the Process Plant (for use as recycle process water) or to the LLCF (for Discharge though Cell E). 8. Monitor and report on the deposition plan according to the requirements of the Water Licence, the WPKMP, and good practice. The Deposition Plan achieves a number of operating, environmental and closure benefits, including the following: integration of completed mining areas into on-going operations to reduce surface disturbances; secure FPK deposition close to the Process Plant for the duration of the planned mine life; early reduction of FPK slurry deposition into Cells A and C of the LLCF PKCA, enabling internal FPK beaches and ponds to stabilize in preparation for future progressive reclamation activities; expected improved water quality within the LLCF and correspondingly reduced constituent concentrations in Discharge to the Receiving Environment, Leslie Lake, during the period when FPK slurry water is accumulating within the Panda/Koala PKCA (anticipated in the order of 7-8 years); substantive reduction in the volume of freshwater required for flooding of the Panda and Koala pits for closure, resulting in reduced use of source lakes, shorter pump flooding timeframes, and reduced closure costs; and continued deferral of FPK deposition into Cell D of the LLCF PKCA in accordance with previous commitments. The final overflow elevation from the Panda/Koala pit lake is projected to be masl. A minimum safety operating freeboard of 2 m below overflow is planned. A vertical freeboard of 2 m represents approximately 1.6 million m 3, twice the volume of water projected for a 1:100 extreme wet year. Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V

34 5. Monitoring and Response Programs 5.1 Minewater Minewater quantity and quality monitoring provides important information that is used to confirm predicted wastewater quantity and quality trends, confirm assumptions, define adaptive management strategies should differing trends be observed, and confirm compliance with the Water Licence Discharge criteria and the MDMER. Minewater monitoring is defined and carried out in accordance with the Surveillance Network Program (SNP) of the Water Licence and the Final Discharge Points (FDPs) of the MDMER. Additional monitoring is also carried out when necessary to meet operating needs. SNP and FDPs water monitoring is focused on point source Discharges (such as the LLCF, TRSP and KPSF). Key internal locations for the SNP program are also monitored (such as the PKCAs and other Minewater management facilities). Sampling protocols are described in an analyst-approved Quality Assurance/Quality Control Plan (Dominion 2017). Water quality, water acute and chronic toxicity testing, and flow measurement locations, frequency, and analytical schedules are described in the SNP section of the Water Licence and in the effluent monitoring conditions of the MDMER. Results of the SNP monitoring are reported to the WLWB monthly and in the Water Licence Annual Report. Results of the FDP monitoring are reported quarterly and annually in the Mine Effluent Reporting System (MERS) system. Maps of the SNP monitoring locations and ground temperature cables are available in the SNP monthly report and in the annual summary of ground temperature conditions in the waste rock storage areas (Tetra Tech 2018). In some instances, Minewater monitoring is specifically linked to adaptive management responses through the Water Licence. For example, the Water Licence (W2012L2-0001) requires that predictive water quality and mixing models for the (future) Misery pit Minewater Management Facility be updated based on site-specific monitoring data collected during the early stages of the Jay Pit mining operations, such that EQC and long-term predictions can be re-evaluated if necessary. 5.2 Receiving Environment Water monitoring, and other aquatic and fisheries monitoring in the Receiving Environment is conducted under the Aquatic Effects Monitoring Program (AEMP). The AEMP monitors the aquatic Receiving Environment for changes that may result from mining activities. Under the AEMP, a series of potentially affected lakes and streams, along with reference stations, are monitored for a suite of aquatic parameters. Sampling locations, sampling protocols and analytical schedules are described in the current AEMP Plan as approved by the WLWB. Results of the AEMP monitoring are reported to the WLWB in an annual AEMP report. The sampled lakes and streams include: Reference lakes and streams; the Koala watershed in the vicinity and downstream of the main camp, Panda/Koala and LLCF areas; the King-Cujo watershed downstream of the KPSF; the Pigeon watershed downstream of the Pigeon area; the Horseshoe watershed downstream of Two-Rock Settling Pond; and Lac du Sauvage in the vicinity and of the Jay area (future). An Aquatic Response Framework is in place to link the results of monitoring under the AEMP with response actions, where appropriate, to ensure that mine-related effects in the Receiving Environment remain within an acceptable range (ERM 2018). Through the Aquatic Response Framework, the results of the AEMP are incorporated into an early warning system with defined action levels that allow Dominion to monitor and respond to changes in the Receiving Environment Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V

35 prior to a significant environmental impact occurring. Issue-specific response plans are developed when necessary. Examples of potential effects that were identified and addressed through past or current Response Plans include elevated concentrations of nitrate, chloride and potassium in the LLCF. Action thresholds and response requirements are described in the current ARF as approved by the WLWB. 5.3 Groundwater Monitoring and reporting of deep (i.e. sub-permafrost) groundwater for open pits and underground workings takes place through special studies conducted to support new projects and through operational monitoring to support mine operations and environmental management, as described below. Groundwater monitoring related to closure and reclamation is described in the Interim Closure and Reclamation Plan. Special studies in support of new projects are conducted to meet the technical needs of the project and to address requirements of the permitting process. These studies are reported through the project permitting process and are typically posted on Board public registries. Special studies undertaken to date have focussed on new projects that are anticipated to intersect deep groundwater and for which additional information is necessary, including the following: Sampling of groundwater in the vicinity of the Panda and Koala pits/underground workings in support of initial project permitting. Sampling of groundwater in the vicinity of the (future) Jay open pit. Operational monitoring is conducted to meet the conditions of the Water Licence or other authorizations and is typically reported to the Board s public registry through routine annual reports. Operational monitoring and reporting include the following: Quantity and quality of water pumped from the Panda/Koala/Koala North underground workings, reported in the Annual Water Licence Report (Schedule 1(f), SNP B.7). Quantity and quality of water pumped from the (future) Misery underground workings, to be reported in the Annual Water licence Report (Schedule 1(f), SNP b, SNP B.7). Quantity and quality of water pumped from the (future) Jay open pit to be reported in the Annual Water licence Report (Schedule 1(n)(x), SNP Jay-0003, SNP B.7). Updated water quality modelling for the (future) Misery Pit Water Management Facility as part of Jay project is a requirement of the Water Licence (Condition H.23) and will include the results of operational groundwater monitoring. 5.4 PKCA Operational Monitoring General operational monitoring of FPK deposition includes: Once per 12-hour shift visual inspection of active FPK Discharge spigot locations at the active LLCF, and the road-accessible perimeter of Cells A and C to active FPK spigot Discharge locations. Once per 12-hour shift visual inspection of the Beartooth and Panda/Koala FPK pipelines when active. Recording of daily processing rates and tonnages pumped from the LLCF to each PKCA. Records of pumping times and flow rates to individual spigots. Periodic surveys of the beaches (LLCF) and bathymetry (LLCF and Beartooth PKCA) to determine deposit geometry and enable refinements to the day-to-day deposition sequencing. Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V

36 Once it is operational, the Panda/Koala PKCA will be incorporated into the operational monitoring procedures. FPK deposition monitoring has provided several key findings that have been used to re-focus and optimize deposition strategies, such as: Observed and investigated ice lensing within FPK resulted in the now standard procedure of rotating deposition between various spigots in the LLCF during the winter season to avoid excessive ice formation. Monitored FPK beach slopes and properties led to the determination to maximize the available storage potential of Cells A, B and C (i.e., deposition from the east and then the west sides of Cell B resulted in overlying beaches with a relative low line east of the midsection to facilitate drainage for closure). Monitoring of the FPK profile and settlement surface within the Beartooth PKCA contributed to data used for planning deposition into the Panda/Koala PKCA. 5.5 Long Lake Containment Facility The following monitoring information is collected to measure the performance of the LLCF and provide feedback for operational refinements: Water quality within the PKCA is monitored through minimum annual water sampling in each Cell containing ponded water at various depths in the water column (analysed for full suite of constituent concentrations). This information contributes to planning for Discharge from Cell E, evaluating the operational implications of runoff from FPK beaches, and calibration of long-term water quality prediction models. Sampling and quantity estimation of FPK and Minewater inputs into the PKCA, including Process Plant Discharge water. This information contributes to an understanding of the PKCA internal water balance. Recording of internal water elevations in each Cell, typically on a monthly basis verified by survey on a semiannual basis. This information contributes to planning for Discharge from Cell E, operational pumping between Cells and the PKCA internal water balance. Monitoring of Discharge water quality and volumes in accordance with the requirements of the Water Licence. More frequent water quality sampling and water elevation recording as necessary to fulfill operational needs. This information provides temporary intensive data in support of short-term operational needs. Annual professional engineering inspection and instrumentation data review of the internal dikes and Outlet Dam. This information provides essential safety validation for the dikes and Outlet Dam and will trigger remedial safety work when necessary. Surface survey of FPK beaches through LiDAR and other means. This information contributes to an understanding of FPK consolidation processes and evolution of the placed solids density, and remaining storage capacity. Any additional monitoring required though the Water Licence or other operating authorizations, or otherwise required by the WLWB or another regulator. The collected information is reported to the WLWB and enables on-going evaluation of facility performance against plan such that operational adjustments can be implemented where necessary. Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V

37 5.6 Beartooth PKCA The following monitoring information is collected to measure the performance of the Beartooth PKCA and provide feedback for operational refinements: Water quality within the PKCA is monitored through minimum annual water sampling at various depths in the water column (analysed for full suite of constituent concentrations) and a continuous water column profile using a multi-function probe (typically including ph, temperature, dissolved oxygen, oxidation/reduction potential and conductivity). This information contributes to planning for operational out-pumping to the LLCF, evaluating the operational implications of FPK porewater expulsion due to consolidation, and calibration of long-term water quality prediction models. Sampling and quantity estimation of FPK and Minewater inputs into the PKCA, including Process Plant Discharge water. This information contributes to an understanding of the PKCA internal water balance. Recording of PKCA water elevation, typically on a monthly basis verified by survey on a semi-annual basis. This information contributes to planning for operational out-pumping to the LLCF and the PKCA internal water balance. More frequent water quality sampling and water elevation recording as necessary to fulfill operational needs. This information provides temporary intensive data in support of short-term operational needs. Annual professional engineering inspection and instrumentation data review of Bearclaw Dam. This information provides essential safety validation for the Dam and will trigger remedial safety work when necessary. Inspection of the physical stability of pit walls along the access ramp to the water level, typically annually or prior to personnel access to the water level. This information provides essential safety validation for personnel accessing the PKCA and will trigger remedial safety work when necessary. FPK profile (i.e., bathymetric survey) through sonic measurement or other means. This information contributes to an understanding of FPK consolidation processes and evolution of the placed solids density and remaining storage capacity. Any additional monitoring required though the Water Licence or other operating authorizations, or otherwise required by the WLWB or another regulator. The collected information is reported to the WLWB and enables on-going evaluation of deposition performance against plan such that operational adjustments can be implemented where necessary. Monitoring data collected at the Beartooth PKCA has been and will continue to be used in planning for FPK deposition into the Panda/Koala PKCA. 5.7 Panda/Koala PKCA The following monitoring information will be collected to measure the performance of the Panda/Koala PKCA, once it is activated, and provide feedback for operational refinements: When the internal water elevation has reached a safely accessible elevation, water quality within the PKCA will be monitored through minimum annual water sampling at various depths in the water column of each component pit (analysed for full suite of constituent concentrations) and a continuous water column profile in each component pit using a multi-function probe (typically including ph, temperature, dissolved oxygen, oxidation/reduction potential and conductivity). This information contributes to planning for operational outpumping, evaluating the operational implications of FPK porewater expulsion due to consolidation, and calibration of long-term water quality prediction models. Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V

38 Sampling and quantity estimation of FPK and Minewater inputs into the PKCA, including Process Plant Discharge water. This information contributes to an understanding of the PKCA internal water balance. Recording of PKCA water elevations in each component pit, typically on a monthly basis verified by survey on a semi-annual basis. This information contributes to planning for operational out-pumping and the PKCA internal water balance. More frequent water quality sampling and water elevation recording as necessary to fulfill operational needs. This information provides temporary intensive data in support of short-term operational needs. Annual professional engineering inspection and instrumentation data review of Panda Dam. This information provides essential safety validation for the Dam and will trigger remedial safety work when necessary. Inspection of the physical stability of pit walls along the access ramps to the water level in each component pit, typically annually or prior to personnel access to the water level. This information provides essential safety validation for personnel accessing the PKCA and will trigger remedial safety work when necessary. FPK profiles (i.e., bathymetric survey) through sonic measurement or other means in each component pit. This information contributes to an understanding of FPK consolidation processes and evolution of the placed solids density and remaining storage capacity. Any additional monitoring required though the Water Licence or other operating authorizations, or otherwise required by the WLWB or another regulator. The collected information will be reported to the WLWB and will enable on-going evaluation of deposition performance against plan such that operational adjustments can be implemented where necessary. 5.8 Other Minewater Management Facilities Other Minewater Management Facilities that will be monitored are TRSP, KPSF and, in future, Misery pit. The following monitoring information will be collected to measure the performance of the facilities and provide feedback for operational refinements: Annual professional engineering inspection and instrumentation data review of Two-Rock Dam and King Pond Dam. This information provides essential safety validation for the Dams and will trigger remedial safety work when necessary. Annual evaluation of the functioning of TRSP and sediment accumulation in the upstream cell. This information will enable an evaluation of future operational performance and will trigger remedial action if necessary to ensure effective sediment settlement. Monitoring of Discharge water quality and volumes in accordance with the requirements of the Water Licence. When the future internal water elevation in Misery pit has reached a safely accessible elevation, water quality within the pit will be monitored through minimum twice-per-year water sampling at various depths in the water column (analysed for full suite of constituent concentrations) and a continuous water column profile using a multi-function probe (typically including ph, temperature, dissolved oxygen, oxidation/reduction potential and conductivity). This information contributes to planning for operational Discharge and calibration of long-term water quality prediction models. Sampling and quantity estimation of primary Minewater inputs into the facilities, including Misery open pit/underground Minewater, Sable open pit Minewater, and future Jay open pit Minewater. This information contributes to an understanding of the facility internal water balance. Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V

39 Recording of water elevations in each facility, typically on a monthly basis verified by survey on a semi-annual basis. This information contributes to planning for operational Discharge and facility water balance. More frequent water quality sampling and water elevation recording as necessary to fulfill operational needs. This information provides temporary intensive data in support of short-term operational needs. Any additional monitoring required though the Water Licence or other operating authorizations, or otherwise required by the WLWB or another regulator. 5.9 Special Studies Special studies are conducted periodically to investigate specific issues related to wastewater management and PK deposition. These are reported to the WLWB as appropriate. Special studies will be undertaken as needed to ensure safe and compliant operation of the PKCAs. Past special studies have included: A series of integrated water quality prediction models for the Koala Watershed have been developed and have been relied on extensively for regulatory submissions, operational planning and closure planning. The models are updated when substantive new information is available or when new operational needs arise. The integrated series of models includes: o o o o LLCF (Cells D and E); Panda/Koala PKCA; Beartooth PKCA; and a series of lakes and connecting streams in the Koala watershed downstream of the LLCF (Leslie, Moose, Nero, Nema, Martine and Sipper). A series of Site-Specific Water Quality Objectives have been developed and utilized in evaluating effects and implementing adaptive management responses. Site-Specific Water Quality Objectives have been developed for sulphate, nitrate, potassium, chloride, molybdenum and vanadium. Response Plans are developed and implemented when receiving water monitoring data (i.e., collected through the AEMP) indicates an unexpected potential mine-related effect. Each Response Plan constitutes a special study to investigate, understand and address, when necessary, the potential effect. A 2013 winter season drill investigation was carried at the LLCF to investigate subsurface conditions within the FPK deposits in Cells B and C. The study findings were reported to the WLWB and have been used in reclamation research and closure planning. Laboratory consolidation testing of FPK was carried out in 2017 in preparation for FPK deposition into the Panda/Koala PKCA. The laboratory data was used in conjunction with physical monitoring data from the Beartooth PKCA to predict potential long-term consolidation and porewater expulsion in the Panda/Koala PKCA. A future study is planned to optimize the most appropriate depth of freshwater cap over FPK in the Panda/Koala PKCA at the time of closure of the PKCA. This is a reclamation research study described in the ICRP, Version 3.0 (Dominion 2018) Adaptive Management Since operations began in 1998, adaptive management principles have been effectively applied to the environmental management of the Ekati mine. The cycle of adaptive management steps is illustrated below. Monitoring programs currently in place and described above will detect potential undesirable physical and environmental changes caused by wastewater and processed kimberlite management. If this occurs, the likely causes will be Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V

40 determined, and management plans will be revisited. The Dominion Aquatic Response Framework (Section 5.2) links monitoring results of the AEMP with actions necessary to ensure that mine-related effects in the Receiving Environment remain within an acceptable range. Recent and current examples of adaptive management include response programs that have effectively managed increasing concentrations of chloride, nitrate and potassium in the LLCF to maintain compliance at the point of Discharge (Cell E). Initial Responses Identification of issue Verification of trigger Determing if additional sampling is required Development of strategic response plan Possible Adaptive Management Reponses Additional studies developed to determine extend and impact Development of Ecological Risk Assessments Modification of WPKMP or WROMP Temporary use of contingency allowances Implementation of Adaptive Management Responses Implementation of modified programs Design of mitigation structures/facilities Construction of mitigation structures/facilities Following implementation of appropriate adaptive management responses, Dominion would continue with sampling, monitoring and evaluation to confirm issues have been satisfactorily addressed. Future adaptive management strategies may involve improvement or modifications of environmental management plans (such as the AEMP, WROMP or this Plan for example), or temporary use of the contingency allowances included in Minewater management facility design. Water management structures have been designed to provide for contingency (e.g., safety factor included in the design of the pumping systems, freeboard included in the design of containment facilities) which allows accommodating unexpected hydrologic and operational conditions, as required. Potential adaptive management measures range in scale from increasing the size of pumping systems, use of additional pumps, increasing size of the sumps, development of additional sumps, and/or implementing adjustments to the water management strategies. Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V

41 6. Closure and Reclamation The reclamation goal for the Ekati mine, as approved by the WLWB through the ICRP report (BHP Billiton, 2011) is to return the Ekati mine site to viable, and wherever practicable, self-sustaining ecosystems that are compatible with a healthy environment, human activities, and the surrounding environment. The reclamation goal is supported by specific objectives and completion criteria for each type of development (e.g., open pits, underground workings, roads). Reclamation of the wastewater and processed kimberlite management facilities are designed to fit into this established framework and are found in the closure and reclamation plans. This section provides an overview of current closure plans, the detailed descriptions are included in the approved ICRP report (Version 2.4) and proposed ICRP report (Version 3.0) and other subsequent related WLWB approvals. 6.1 Long Lake Containment Facility At the end of PK deposition, it is estimated that an area of approximately 728 ha (Cell B = 199 ha, Cells A and C = 529 ha) will need to be reclaimed. Based on reclamation research results, three distinct topographic units that will develop within LLCF in closure have been identified: 1) gently sloping, well-drained PK beaches (for revegetation); 2) residual ponds in Cells A, B, and C; and 3) interface shorelines where beach deposits meet the ponds. Each unit will have predictable geomorphic attributes, geographic distribution, and soil properties that allow for evaluation and optimization of reclamation prescriptions. Figure 21 shows the proposed reclaimed LLCF after the closure activities have been implemented; the reclaimed LLCF also shows a conceptual layout of the final LLCF conditions, which includes vegetation and rock, residual ponds, pond interface, and drainage. Dominion's commitments through the Jay Project EA review, research studies will continue at the LLCF and will transition to reclamation of completed areas as the study results provide final definition of reclamation procedures. The planned transition of FPK deposition from the LLCF as primary PKCA to the Panda/Koala pits as the primary PKCA may facilitate progressive reclamation at the LLCF by providing additional suitable areas. Based on the 2018 LOM Plan, it is expected that Cells A, B, and C of the existing LLCF can be progressively reclaimed during Jay Pit mining. The overall reclamation goal for the LLCF is to design and construct a long-term cover that will physically stabilize the PK with a landscape that will be safe for human and wildlife use. Dominion has also sought TK input into the plans for the progressive reclamation of the LLCF. Progressive reclamation by the active and passive establishment of natural vegetation has been occurring since 2004, and LLCF reclamation research at Cell B has been ongoing at the Ekati mine since 2012 to develop prescriptions for vegetation growth on the PK beaches in the LLCF. Residual ponds and drainage channels have been established in Cell B. Surface water management research through trial channel construction and further bio-engineering of existing channels so that they are stabilized for closure is also being completed. 6.2 Beartooth, Panda, Koala and Koala North Pits Once PK deposition and minewater management is completed, the pits will be flooded to create pit lakes. Figure 22 shows the planned final pit lake configuration at closure for Panda, Koala, Koala North, and Beartooth Pits. Flow will be re-established from Bearclaw Lake through Beartooth Pit Lake by breaching the Bearclaw Dam and constructing an inflow stream that makes use of the pre-existing flow path. An outflow channel to Upper Panda Lake will be established that makes use of the pre-existing flow path. Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V

42 Beartooth Pit the ongoing placement of FPK in the pit will reduce the pumping requirements at closure. Active backflooding of Beartooth Pit is expected to be completed prior to final closure of the site. Panda, Koala, and Koala North pits Placement of PK into these pits and underground workings will take place during Ekati mine operations, which will reduce the pumping requirements at closure. Freshwater cap back-flooding and final reclamation will not take place until final closure. The PDC will remain in place post-closure. This will continue the diversion of the majority of flow from Upper Panda Lake around Panda and Koala pit lakes to Kodiak Lake. A spillway will be constructed around the Panda Dam that will allow safe passage of flood flows. This is a precautionary measure to protect against general flooding of the area in a flood event or if the PDC is temporarily blocked with snow during freshet. A channel between Panda Pit Lake and Koala Pit Lake (which will include a flooded Koala North Pit) will be constructed to reconnect surface drainage. An outflow channel from Koala Pit Lake to Kodiak Lake will be constructed utilizing the pre-development channel. An outflow channel from Koala Pit Lake to Kodiak Lake will be constructed utilizing the pre-development channel. 6.3 Misery Pit The mined-out Misery Pit is a primary Minewater management facility for the Project. The Jay Project Closure and Reclamation Plan (Golder 2016) describes the closure and reclamation measures for the Misery Pit. The fundamental approach to closure of the Misery Pit is to create a pit lake, with outflow water quality that is safe for people, wildlife, and fish. This will be accomplished by providing a 60 m deep freshwater cap over Minewater that contains elevated salinity (TDS). This approach will create a stable meromictic condition with distinct upper and lower layers. This approach was confirmed through hydrodynamic modelling of the Misery pit lake in post-closure, which was reviewed through the Environmental Assessment of the Jay Project. Once filled with water for closure, the Misery pit lake will overflow intermittently to the Receiving Environment (Lac de Gras). After the use of the Misery Pit as a Minewater management facility during operations, the permanent reclamation of the pit would proceed. Final closure of the Misery Pit will involve lowering the in-pit water level to approximately 60 m below the final overflow elevation by pumping water into the mined-out Jay Pit, and then creating a 60 m cap of freshwater over the higher salinity Minewater in the deeper part of the Misery Pit. The depth of the freshwater cap (60 m) is taken from the hydrodynamic modelling, which, by necessity, is based on several conservative assumptions. Therefore, DDEC will collect site-specific data during operations at the Jay Pit and will conduct additional technical studies in future to optimize a sitespecific depth of freshwater required for closure and reclamation. A combination of catchment area runoff, precipitation, and freshwater pumped from Lac du Sauvage will be used to create the freshwater cap. Consideration may be given during future optimization studies to pumping freshwater from Lac de Gras. Once the freshwater cap is created and water quality has been demonstrated to be suitable for Discharge, a hydraulic connection to the natural outflow channel to Lac de Gras will be re-established to allow for safe water overflow from the surface of the Misery pit lake to Lac de Gras. Other reclamation activities associated with the Misery pit will be implemented as described in the Ekati mine ICRP, as updated through the Annual Reclamation Progress Reports. Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V

43 6.4 Jay Pit and Dike At completion of mining the Jay pipe, elevated TDS water from Misery will be pumped into the mined-out Jay Pit, where it will occupy the lower half of the pit (based on elevation). Once this has been completed, the remaining volume in the Jay Pit and the diked area will be back-flooded with freshwater to facilitate creation of a freshwater cap and to re-establish natural water levels in the diked area. Water for back-flooding will come from a combination of runoff, precipitation and from Lac du Sauvage. Water from Lac du Sauvage will be pumped over the dike in a controlled manner to control the generation of TSS. Once water quality within the back-flooded Jay Pit and the diked area is demonstrated to be suitable for mixing with the natural lake water, the dike will be locally breached, and the Sub-Basin B Diversion Channel will be regraded to promote natural drainage. Based on the results from the water balance model, back-flooding of the Jay Pit and diked area would be achieved in about 3.5 years (assuming average climate conditions) and is expected to have acceptable minimal impacts to the level and local hydrological regime in Lac du Sauvage and Lac de Gras. Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V

44 7. References BHP Billiton (BHP Billiton Canada Inc.) Year Performance Review of: Ekati Mine Processed Kimberlite Containment Facility and Assessment of Options for Optimized Future Development; Summary Report on the Evaluation of Ekati Long Lake Containment Facility Five-Year Review Multiple Accounts Analysis, July 4, BHP Billiton. 2011a. Ekati Diamond Mine, Interim Closure and Reclamation Plan. Version 2.4 submitted to the Wek èezhìı Land and Water Board. August BHP Billiton. 2011b. Ekati Diamond Mine: Wastewater and Processed Kimberlite Management Plan Version 2.0. Submitted to Wek èezhìi Land and Water Board. Dated October DDEC (Dominion Diamond Ekati Corporation) Old Camp closure and reclamation plan. Prepared by Dominion Diamond Ekati Corporation: Yellowknife, Northwest Territories. December 30, 2013 DDEC Developers Assessment Report for the Jay Project. Prepared by Dominion Diamond Ekati Corporation. October Dominion (Dominion Diamond Ekati ULC) Water Surveillance Network Program (SNP) Quality Assurance/Quality Control (QA/QC) Plan. April Dominion (Dominion Diamond Ekati ULC) Ekati Mine Interim Closure and Reclamation Plan Version 3.0. August ERM (ERM Consultants Canada Ltd.) Ekati Diamond Mine: 2017 Koala Watershed Water Quality Model. Prepared for Dominion Diamond Ekati Corporation by ERM Consultants Canada Ltd. ERM Ekati Diamond Mine: Aquatic Response Framework. Version 3.0. Prepared for Dominion Diamond Ekati Corporation by ERM Consultants Canada Ltd. Golder Jay Project Conceptual Closure and Reclamation Plan. Prepared for Dominion Diamond Ekati Corporation. Golder Associates Ltd., June Golder Ekati Mine- Pit Lake Closure Water Quality Modelling. Prepared for Dominion Diamond Ekati ULC. Golder Doc. No E17057-TM-Rev January 17, MVEIRB (Mackenzie Valley Environmental Impact Review Board) Report of Environmental Assessment and Reasons for Decision Dominion Diamond Ekati Corp. Jay Project. EA February 1, RGC (Robertson GeoConsultants Inc.) Ekati Mine Long Lake Containment Facility: The Nature & Occurrence of Extra Fine Processed Kimberlite. Report Number /1. Prepared by Robertson GeoConsultants Inc. for BHP Billiton Canada Inc. September 12, SRK (SRK Consulting Canada Inc.) Waste Rock and Waste Rock Storage Area Seepage Survey Report: Ekati Diamond Mine. Prepared for Dominion Diamond Ekati ULC by SRK Consulting Canada Inc. April Tetra Tech (Tetra Tech Canada Inc.) Summary of Ground Temperature Conditions in Waste Rock Storage Areas, Ekati Diamond Mine NT. Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V.9.0 R-1

45 Figures

46 Figure 1 Life of Mine Plan Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V.9.0 F-1

47 Figure 2 Ekati Diamond Mine Satellite Imagery Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V.9.0 F-2

48 Figure 3 Ekati Main Camp Area Satellite Imagery, 2017 Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V.9.0 F-3

49 Figure 4 Misery Site Satellite Imagery, 2017 Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V.9.0 F-4

50 Figure 5 Fox Site Satellite Imagery, 2017 Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V.9.0 F-5

51 Figure 6 Pigeon Site Satellite Imagery, 2017 Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V.9.0 F-6

52 Figure 7 Lynx Site Satellite Imagery, 2017 Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V.9.0 F-7

53 Figure 8 Sable Site Satellite Imagery, 2018 Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V.9.0 F-8

54 Figure 9 Jay Project Development Map (Jay, Misery and Lynx Sites) Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V.9.0 F-9

55 Figure 10 Main Camp Site Surface Minewater Collection Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V.9.0 F-10

56 Figure 11 Minewater and Processed Kimberlite Management at the Ekati Main Site Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V.9.0 F-11

57 Figure 12 Water Management for Misery Site, Current Configuration Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V.9.0 F-12

58 Figure 13 Water Management for the Sable Pit Area Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V.9.0 F-13

59 Figure 14 Minewater Management at Misery Site for Jay Project Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V.9.0 F-14

60 Figure 15 Ekati Diamond Mine Water and Liquid Waste Summary Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V.9.0 F-15

61 Figure 16 Ekati Diamond Mine Solid Waste Summary Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V.9.0 F-16

62 Figure 17 Long Lake Containment Facility Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V.9.0 F-17

63 Figure 18 The Reclaim Water Barge in Cell D of the LLCF Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V.9.0 F-18

64 Figure 19 Processed Kimberlite Deposition (blue arrow) into the Mined-out Beartooth Pit Figure 20 Beartooth Pit Minewater Decanting Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V.9.0 F-19

65 Figure 21 LLCF Area Current Extent and Closure Plan Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V.9.0 F-20

66 Figure 22 Beartooth, Panda, Koala and Koala North Existing and Final Configuration Date: March 2019 Ekati Diamond Mine Wastewater and Processed Kimberlite Management Plan V.9.0 F-21