Dominion Diamond Ekati Corporation Misery Underground Application Water Licence W2012L2-0001 February 7, 2018
Overview • Management Plans • Closure and Reclamation Plan • Waste Rock and PK Management • Minewater Management • Water Quality and EQC • Security
Management Plans • DDEC included several plans and designs for which they requested Board approval. • GNWT notes that a WL must be issued before a plan can be approved. • GNWT is supportive of an expedited review process due to the nature and importance of some of the proposed plans to DDEC’s early operations.
Management Plans • GNWT recommends that the Board require that the management plans included with the water licence application be submitted as a term and condition of the licence for review and approval. The terms and conditions of the licence should define the required components of these plans.
Closure and Reclamation Plan • DDEC requests approval of closure concepts in order to update the ICRP. • Specifically, DDEC requests certainty of the following key aspects: – Misery Underground surface facilities; – Misery Underground workings; – King Pond; – Lynx Pit; and – Misery Pit. • GNWT’s understanding is that no new closure concepts are being proposed.
Closure and Reclamation Plan • GNWT recommends that the concepts, standards and objectives for closure of site components required for the Misery Pipe remain in the closure plan.
Waste Rock and Processed Kimberlite Disposal • Through the process, GNWT raised questions and concerns regarding waste rock and processed kimberlite disposal. – Waste rock volume and composition, processed kimberlite volume, etc. • These concerns were addressed through the IR process as described in the GNWT intervention.
Minewater Management • Mining in Lynx Pit is anticipated to be complete prior to King Pond Sforage Facility (KPSF) reaching its water storage capacity. • Should the KPSF fill to the design limit before Lynx Pit is available, DDEC has stated that mining in Lynx Pit will stop and Lynx Pit will start receiving minewater from Misery Underground. • DDEC also provided alternative options for Misery Underground water if the KPSF reached capacity sooner than anticipated.
Minewater Managment • GNWT recommends, as part of SNP monitoring and reporting, that inflows into the MUG be monitored and reported quarterly as well as the remaining storage capacity within King Pond. These mine inflows should be used to model how long it will take to reach capacity within King Pond and ensure the Lynx Pit is available to receive minewater from Misery Underground.
Water Quality Modeling Updates • DDEC completed updates to the Misery Underground Water Quality Model to evaluate the influence of the MUG Project on the water quality predictions completed for the Jay Project. • The Misery Underground Project modeling was also evaluated to determine that closure could proceed without the Jay Project advancing.
Water Quality Modeling Updates • As part of the GNWT’s review, Information Requests were provided and responses were provided by DDEC which included additional information. • However, the GNWT has a few outstanding concerns regarding the most recent modeling updates, and further information is required to fully assess the predicted water quality conditions. • GNWT refers the Board to our Intervention for specific comments and outstanding concerns.
Water Quality Modeling Updates • GNWT recommends that DDEC submit a Water Quality Modeling Special Study addressing outstanding items on the water quality modeling updates, including updating predicted total phosphorus predictions for Lac de Sauvage. The study should address the items described in the attached memorandum (Appendix A) by Zajdlik and Associates Ltd. The study should be submitted within one year of Water Licence approval. Any EQC established within the licence should be revised, if needed, to reflect the results of this study.
King Pond Settling Facility • DDEC has noted that as long as water meets EQC, discharge from the KPSF would occur. • No chloride EQC currently exists for the KPSF. • DDEC has discussed and developed specific contingencies that alleviate the need for discharge from the KPSF. • Therefore, its not clear to the GNWT why operational flexibility is required for discharge from King Pond.
King Pond Settling Facility • GNWT recommends operational measures be implemented to the greatest extent to alleviate the need to discharge from King Pond during the MUG project. Any EQC established for chloride should be based upon an appropriate receiving water hardness.
King Pond Settling Facility • DDEC identified other parameters as potentially requiring EQC i.e., aluminum, cadmium, chromium, iron and uranium. • Again, it is unclear whether EQC are required, given the discharge contingenciess provided by DDEC. • GNWT is concerned that for parameters listed, concentrations are predicted at levels that will exceed SSWQOs in Cujo Lake. • EQC’s for any discharge from the KPSF would be required to ensure that SSWQOs in the receiving environment are maintained (MVLWB Policy, 2011)
King Pond Settling Facility • GNWT recommends operational measures be implemented to the greatest extent to alleviate the need to discharge from King Pond during the MUG project.
King Pond Settling Facility • GNWT recommends that, should the Board determine that discharge from the KPSF to the environment is required, EQC must be set to ensure that water quality objectives in the receiving environment will be achieved. Mitigation strategies should be developed and implemented to prevent exceedances of calculated EQCs and downstream SSWQOs for aluminum, cadmium, chromium, iron and uranium.
Cadmium Hardness Adjusted EQC • DDEC proposed a hardness adjusted EQC for cadmium that follows CCME guidance for the KPSF discharge station (SNP 1616-43). • In developing the EQC, DDEC applied a dilution factor of 1.7 based on the annual natural runoff volume that reports to Cujo Lake and the annual discharge volume from the KPSF. • The GNWT identified concerns with using this dilution factor when the volume and rate of discharge from King Pond to Cujo Lake is not known at this time.
Cadmium Hardness Adjusted EQC • GNWT recommends that DDEC should not rely on an unvarying dilution factor when it is not known what discharge from the KPSF will be for conversion of a site-specific water quality objective to a maximum average concentration. DDEC should modify the cadmium EQC calculation to include a temporally-relevant dilution factor.
Cadmium Hardness Adjusted EQC • GNWT recommends that DDEC, as part of the above recommended Water Quality Modeling Special Study, should present and discuss an appropriate hardness for use when estimating EQC for cadmium. The study should also address the items described in the attached memorandum (Appendix A, Section 4.2) by Zajdlik and Associates Ltd regarding the cadmium EQC. Any EQC established within the licence should be revised, if needed, to reflect the results of this study.
Security • DDEC’s estimate includes costs to pump MUG mine water stored in Lynx Pit. – Prior to utilizing Lynx Pit for final dewatering from the Jay diked area. • GNWT assumes with the “no Jay” scenario, mine water will still be pumped back to MUG. – This would be required to achieve WQOs in Lynx Pit at closure.
Security • DDEC identified that costs to remove salvageable mobile equipment and cleaning non-salvageable equipment and materials for the MUG prior to flooding would be minimal, and therefore, did not add any costs to the security estimate. • GNWT does not agree and notes that similar costs associated with the Koala underground mine should be considered.
Security • GNWT recommends that DDEC review the existing security allowance for decontamination and decommissioning of the Koala underground and that similar costs be included for the Misery underground mine unless DDEC can provide rationale as to why a different cost would be appropriate.
Security • GNWT recommends, to avoid confusion, that the activity for lowering the Lynx Pit water levels be included for the Lynx Open Pit table of RECLAIM as opposed to the Misery Open Pit.
Thank You
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