WATER TER QUALIT ALITY Y MODELLING ODELLING AND D EFFL FLUEN UENT T QUALIT ALITY Y CRI RITERI TERIA MVLWB Technical Session Snap Lake Mine Final Closure, and Water Licence and Land Permit Renewal July 16 to 18, 2019 PUBLIC LIC PRESEN ENTATION ION
OUTL TLINE • Water Quality Models - Site, Snap Lake, and Downstream • Effluent Quality Criteria • Model Sensitivities and Near-field Modelling 1
WATER TER QU QUAL ALIT ITY Y MO MODELS ELS
INTR TRODU ODUCTION CTION L I N K E D M O D E L S Water Quantity Model Downstream Lakes Water Quality Site Water Quality Model Model Snap Lake Water Quality Model Effluent Constructed Quality Wetland Criteria Design 3
INTR TRODU ODUCTION CTION CONTINUED TINUED M O D E L A S S U M P T I O N S • Extended Care and Maintenance - Modular water treatment plant (WTP)/reverse osmosis (RO) unit operational • Closure - Buildings decommissioned, North Pile covered, modular WTP/RO unit operational, passive treatment systems constructed and functioning • Post-closure - The modular WTP/RO unit decommissioned, effluent from passive treatment systems meets effluent quality criteria (EQC) - Passive treatment systems were not included in the Site model 4
SITE E MODEL DEL L I N K E D M O D E L S Water Quantity Model el Downstream Lakes Water Quality Site Water Quality Model Model Snap Lake Water Quality Model Effluent Constructed Quality Wetland Criteria Design 5
SITE E MODEL DEL CONCEPTU CEPTUAL DIAGR GRAMS AMS E X T E N D E D C A R E & M A I N T E N A N C E A N D P O S T - C L O S U R E C L O S U R E Sump 1 Sump 1 Sewage Treatment Plant Sump 2 Sump 2 Sump 3 Sump 3 Snap Lake Water Modular WTP North Pile Snap Lake Management North Pile + RO Unit Pond Sump 4 Sump 4 Underground Sump 5 Sump 5 Mine Western Western Embankment Embankment Catchment Catchment Pumping ing Runoff off + Seepage Seepage Outflow low (gravit ity) 6
SITE E MODEL DEL INFL FLOWS & OUTFL TFLOWS The North Pile sumps included inflows and outflows from: 1. Direct precipitation 1 5 2. Inflows/concentrations from the North Pile 3. Inflows/concentrations from sump catchment area 2 6 4. Inflows/concentrations from other sumps North th Pile e 5. Evaporation 3 Sump mp 6. Pumping to the water management pond/outflow Volum lume/ e/ 4 Conc 7
SITE E MODEL DEL WATER ER QUALI ALITY SOURCE CE TERMS Source Water er Quality lity Monit itor orin ing Station tion Rib berm seepage SNP 02-02 Fine processed kimberlite runoff (before cover) SNP 02-02 Fine processed kimberlite runoff (after cover; May and June) SNP 02-02 Fine processed kimberlite runoff (after cover; July to April) SNP 02-02 Fine processed kimberlite draindown SNP 02-02 North Pile embankment seepage SNP 02-02 and SNP 02-05 Western embankment catchment area SNP 02-02 Natural catchment area Stream 1 Developed catchment area SNP 02-05 Sewage treatment plant SNP 02-16i Underground water quality SNP 02-01 8
SITE E MODEL DEL PREDICTED DICTED WATER ER MANAGEME GEMENT T POND D INFL FLOWS S AND OUTFL FLOWS A N N U A L O U T F L O W S ( m 3 ) A N N U A L I N F L O W S ( m 3 ) Catchment Runoff Precipitation Underground Evaporation Sewage Treatment Plant North Pile Modular WTP + RO Unit Seepage to Snap Lake 5,000 35,000 13,000 4,000 150,000 154,000 270,000 5,000 9
SITE E MODEL DEL PREDICTED DICTED DISCHAR SCHARGES S TO SNAP LAKE Annual al Disc schar harge ge to Snap p Lake e (m 3 ) Operations ECM and Closure Post-closure >18,000,000 300,000 270,000 22 22 Annual Volume Discharged to Snap Lake (m 3 ) Millions Annual Volume Discahrged to Snap Lake (m 3 ) Millions Operations ECM Closure Post-closure 20 20 18 18 16 16 14 14 12 12 10 10 8 8 6 6 4 4 2 2 0 0 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 2043 2044 2045 2046 2047 2048 2049 Year Year Water Treatment Plant Modular Water Treatment Plant + Reverse Osmosis Unit Underground Mine Sump 3 Sump 5 10 10
SITE E MODEL DEL PREDICTED DICTED NITRA TRATE TE CONCENT CENTRA RATION TIONS • In Closure, concentrations in Sump 3 are predicted to increase because Sump 3 receives a greater proportion of North Pile runoff • In Post-closure, concentrations in the sumps are predicted to decrease because of the assumption that the sumps fill to their maximum volume before overflowing Sump 3 250 Sump Volu olumes (m 3 ) ECM Closure Post-closure Sump 200 Nitrate, as N (mg/L) Closu osure Post-closu losure 150 3 8,300 61,000 100 5 11,700 68,000 50 0 2018 2020 2022 2024 2026 2028 2030 2032 2034 2036 2038 2040 2042 2044 2046 2048 Reviewe wer comment nts: Year 11 11 • ECCC-08, MVLWB-55: discuss decreases in predicted sump concentrations
SITE E MODEL DEL ANNUAL AL NITRA TRATE TE LOAD D TO SNAP LAKE Annual al Nitrate e Load ad to Snap ap Lake e (kg N/yr) Operations ECM and Closure Post-closure 90,000 5,000 <12,100 100,000 100,000 Post-closure Operations ECM Closure 90,000 90,000 Nitrate Load to Snap Lake (kg N/yr) Nitrate Load to Snap Lake (kg N/yr) 80,000 80,000 70,000 70,000 60,000 60,000 50,000 50,000 40,000 40,000 30,000 30,000 20,000 20,000 10,000 10,000 0 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 2003 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 Modular Water Treatment Plant + Reverse Osmosis Unit Underground Mine Sump 3 Sump 5 ECM - Extended Care and Maintenance 12 12
SNAP LAKE MODEL EL L I N K E D M O D E L S Water Quantity Model el Downstream Lakes Water Quality Site Water Quality Model Model Snap Lake Water r Quality Model Effluent Constructed Quality Wetland Criteria Design 13 13
SNAP LAKE MODEL EL CONCEP EPTU TUAL AL DIAGRAMS GRAMS E X T E N D E D C A R E & M A I N T E N A N C E P O S T - C L O S U R E A N D C L O S U R E Sump 3 Natural Water Natural North Pile Outflow Runoff Management Runoff Pond Modular WTP Camp Use + RO Unit North Pile Snap Lake Downstream Snap Lake Sewage Treatment Plant Sump 5 Site Runoff Underground Site Runoff Outflow Downstream Mine Seepage Pumping ing Runoff off Outflo low 14 14
SNAP LAKE MODEL EL INPUT PUTS S FOR R EXTENDED ENDED CARE RE & MAINTEN TENANCE ANCE AND CLOSU SURE RE North Pile Seepage Camp Use Outflow Site Runoff Modular WTP + RO Unit Discharge Water Management Pond Seepage Stream 1 Other Inflows/Outflows • Precipitation • Other Stream Inflows Evaporation • • Seepage from Underground Mine to Snap Lake 15 15
SNAP LAKE MODEL EL INPUT PUTS S FOR R POST-CLOSURE OSURE North Pile Seepage Outflow Site Runoff Sump 5 Outflow Sump 3 Outflow Stream 1 Other Inflows/Outflows • Precipitation • Other Stream Inflows • Evaporation 16 16
SNAP LAKE MODEL EL WATER TER QUAL ALITY SOURCE E TERMS Input Water er Quality lity Source e Ter erm Treated effluent discharge from the WTP Time series from SNP 02-17 and SNP 02-17b Treated effluent discharge from the modular WTP + ECM and Closure: Median from the Site model RO Unit WMP pumping to Snap Lake (2003-2004) Time series from SNP 02-14 WMP pumping to the underground Mine ECM and Closure: Median from the Site model Calibration period: Time series from SNP 02-14 WMP seepage ECM and Closure: Median from the Site model Calibration period: Time series from SNP 02-05 Uncontrolled site runoff ECM, Closure and Post-closure: Median from Stream 1 17 17
SNAP LAKE MODEL EL WATER TER QUAL ALITY SOURCE E TERMS S CONTINUED TINUED Input Water er Quality lity Source e Ter erm Natural wetland Calibration period: Time series from SNP 1735-11 Calibration period: Time series from Stream 1 Natural watershed runoff ECM, Closure and Post-closure: Median from Stream 1 Calibration period: Time series from SNP 02-02 North Pile seepage ECM, Closure and Post-closure: Median from SNP 02-02 Post-closure: 95 th percentile from the Site model Sump 3 outflow to Snap Lake Post-closure: 95 th percentile from the Site model Sump 5 outflow to Snap Lake 18 18
SNAP LAKE MODEL EL PREDI DICTED CTED NITRA TRATE TE CONCENT CENTRA RATION TIONS EDGE GE OF THE E MIXING XING ZONE NE IN THE E MAIN N BASIN IN OF • Water quality in Snap Lake is predicted to SNAP AP LAKE improve due to: AEMP Benchmark Minus 25% NO3-N = 25 • Decrease in effluent volume 10 ECM Closure Post-closure 9 • Treatment provided by the modular 8 Nitrate, as N (mg/L) water treatment plant (WTP)/reverse 7 6 osmosis (RO) unit during Extended 5 Care & Maintenance (ECM) and 4 Closure 3 2 1 • Natural inflows 0 2018 2020 2022 2024 2026 2028 2030 2032 2034 2036 2038 2040 2042 2044 2046 2048 • Parameter concentrations are predicted to Year remain below AEMP benchmarks 19 19
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