PU PUBL BLIC IC HEARING EARING SNAP AP LAKE KE MINE NE Snap Lake Mine Closure, Water Licence Renewal (MV2019L2-0004) and Land Use Permit Amendment (MV2017D0032) November 26 and 27, 2019 PUBLIC LIC PRESEN ENTATION ION
OUTL TLINE • Overview of Application • Interventions from GNWT and ECCC - Water Quality Models - Effluent Quality Criteria, Waste Minimization, Mixing Zone - Final Closure and Reclamation Plan - Monitoring and Management Plans - Water Licence Conditions - Security • Comments from SLEMA • Summary 1
OVE VERVIEW VIEW OF OF AP APPLIC PLICATION TION
REGUL GULATOR ORY HISTOR ORY Snap Lake Mine – underground diamond mine, 220 km northeast of Yellowknife • 2008: Mine opened • 2015: Mining ceased • 2016: Extended Care and Maintenance began (to present) • 2017: Underground mine flooded • 2018: Seasonal zero occupancy • 2019: Submission of water licence renewal application 3
OVERVIEW EW OF APPLICA CATION TION • Snap Lake Mine is Closing. We need a water licence that aligns with planned closure re and reclam lamation ation activities ivities • Water Licence renewal application included: - Final Closure and Reclamation Plan - Updated Monitoring and Management Plans - Updated Security - Updated Site and Downstream Water Models - Updated EQC • Water Licence renewal application ensures: - Continued monitoring and reporting - Continued meeting of AEMP benchmarks in Snap Lake and downstream - Meeting of the objectives of the Closure plan (Objectives) - Mechanisms to measure success of closure activities (Criteria) - Meeting the measures of the EIS - Ongoing over-site by MVLWB • Closur ure e goal: l: To return the site and affected areas around the Mine to technically viable and, where practicable, self- sustaining ecosystems that are compatible with a healthy environment and with human activities. 4
AN Storag rage Emuls lsio ion Plant ant TOTAL AL IMAGE GE Airstrip ip North th Pile le Water r Mana nageme ment nt Pond nd Fuel l Storag rage Camp mp Proc ocess ess Plant ant Porta tals ls Water r Trea eated ed Trea eatme ment nt Plant ant Water r Disch scharg rge
OVERVIEW EW OF APPLICA CATION TION Tec echnic ical l Sessio sion • Final Closure and Reclamation Plan based on MVLWB Guidelines (MVLWB, 2013) - Closure Objectives: previously approved in the ICRP - Closure Criteria: refined from previous feedback - Monitoring will continue in closure and post-closure • Water management is limited to surface water ~ 2% of the water volumes managed during operations. • Changes were made in response to review comments and discussion - Updated water quantity and quality models - Updated Effluent Quality Criteria for closure - Constructed wetlands are not required to meet AEMP benchmarks. • Approval of proposed EQC will enable progress of closure activities and meeting of the closure goal 7
OVERVIEW EW OF APPLICA CATION TION Infor ormation mation Request ests s and d Tec echn hnical ical Worksh shop op • Discharge quantity and quality and protection of the environment • Water management has changed substantially 22 Annual Volume Discharged to Snap Lake (m 3 ) Millions Operations ECM Closure Post-closure 20 18 16 14 12 10 8 6 4 2 0 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 2043 2044 2045 2046 2047 2048 2049 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 Year Year Water Treatment Plant Water Management Pond Underground Mine Sump 3 Sump 5 8
OVERVIEW EW OF APPLICA CATION TION Inter erven entio ions • Proposed Effluent Quality Criteria (EQC) and overall Final Closure Plan aligns with pollution prevention principle, Fisheries Act • Measure 1(a) – Fish populations will not be adversely affected with proposed EQC • Measure 1(d) – Total Dissolved Solids (TDS) in MacKay Lake predicted to remain below acceptable limit • Capping of the North Pile to meet the requirement of “No active long - term care” 9
RESPO ESPONSES NSES TO O INT NTER ERVENT VENTION IONS
WATER TER QU QUAL ALIT ITY Y MO MODELS ELS EF EFFL FLUENT ENT QU QUALIT LITY CRITER RITERIA IA WAS ASTE TE MI MINIMIZA NIMIZATION TION
SITE E WATER TER QUALI ALITY MODEL EL: MONITORING ORING DATA • Recommendation GNWT-7 - Site water quality model be updated to include: • Therma mal l monitor nitoring ing data • Sensit itivit ity analy lyses using SNP 02-02 water quality data in May and June and individual sump water quality data • De Beers Response - A thermal al perform ormanc ance e assessmen ent t report will be part of the geot otec echn hnic ical al inspecti tion on report - The thermal performance assessment report will review and evaluate the thermal condition of the North Pile - De Beers has used the most repres esen entat tativ ive e water qualit ality data available for input to the site water quality model - De Beers does not ot belie ieve e that adding ing addit ition ional al conser ervatis atism to the model by assigning SNP 02-02 water quality data to runoff from the North Pile each year in May and June after the North Pile is covered is neces essary - De Beers expects that interaction of precipitation and processed kimberlite within the North Pile will be limited in May and June due to freezing of the cover materials and processed kimberlite in contact with the cover De Beers Intervent entio ion n Respons nse e Report • Appendix B (Response to GNWT), Section 1.7 12 12
AEMP BENCHMARK CHMARKS: S: TOTAL AL DISSOL SOLVED ED SOLIDS DS • Recommendation GNWT-10 • The MVLWB set numerical site-spec pecif ific ic water er qualit lity y objectiv ectives es for total l diss issolv olved ed solid ids and constituent ions of concern for closure and post-closure to ensure compliance with Measure 1 of the Report of EA • De Beers Response - De Beers is not proposing an AEMP benchmark for total dissolved solids because: • De Beers has proposed AEMP bench chma marks ks for constit ituen uents of total l dissolv olved ed solid lids that are protective of aquatic life (Measure 1a) and drinking water (Measure 1b) and an Acceptable Limit for total dissolved solids at Node 22 to protect traditional uses (Measure 1d) • Parameter concentrations in Snap Lake are predicted to remain in below low AEMP bench nchma marks ks and total dissolved solids concentrations at Node 22 in MacKay Lake are predicted to remain below the Acceptable Limit to meet Measure 1d • The rationale for proposing an AEMP benchmark for total dissolved solids during Operations was that the ionic composition of water in Snap Lake was expected to remain the same • During Closure and Post-closure, the ionic ic compos mposit ition ion of water er in Snap p Lake ke is expec ected to change nge Concentrations of total l dissolv olved ed solid lids in Snap p Lake e are below low the aestheti etic c Canadian ian water er qualit lity y guid ideli eline ne for drinking inking water er • De Beers Intervent entio ion n Respons nse e Report • Appendix B (Response to GNWT), Section 1.10 13 13
AEMP BENCHMARK CHMARKS: S: HARDNES ESS S CONCENTRA RATI TIONS • Recommendation GNWT-8 - The GNWT recommends hardnes ess-bas ased ed AEMP P benchm hmarks arks be calc lculat lated ed using hardness concentrations in Snap Lake before the Snap Lake Mine began operating and the screening process for parameters of potential concern be updated based on the revised hardness-based AEMP benchmarks • De Beers Response - De Beers does not agree with the recommendation from the GNWT for four reasons: 1. Hardness adjustment to background is inco cons nsistent istent with CCME (2007) 7) guid idance nce 2. Hardness adjustment to background, as an expression of policy, is inco cons nsis istent ent with scienc ience 3. Uncertainty can be addressed in the model calculations for parameters and their toxicity modifying factors, rather than use of unrea ealis listic ic hypot othetica ical l scena enarios ios 4. 4. Preced cedent ent in application to other er norther ern n mines es De Beers Intervent entio ion n Respons nse e Report • Appendix B (Response to GNWT), Section 1.8 14 14
MIXI XING G ZONES ES • Recommendation - The GNWT recommends (GNWT-6): • The MVLWB not approve the proposed mixing ing zones es of 200 metres es for the East and West Influent Storage Ponds. Mixing zone dimensions should be set after plume delineation studies are completed. • In the interim, the mixing ing zones es could ld be set at 200 metres es for the existi isting ng dif iffus user er and 100 m for the East and West Influent Storage Ponds • De Beers Response - A 200m mixing zone is required. - De Beers agrees that the size and location of the mixing zone at the diffuser should remain the same (i.e., 200 m) - De Beers is also proposing 200 m mixing zones for the new discharge locations to the main basin and northwest arm during Closure and Post-closure - De Beers does not believe that the assumptions included in the linked models were too conservative De Beers Intervent entio ion n Respons nse e Report • Appendix B (Response to GNWT), Section 1.6 15 15
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