Con Mine Project Description Water Licence Technical Session March 1 st & 2 nd , 2018
MNML Introduction Past History of project and environmental compliance Present Site Overview, Status of Reclamation, in place and available technology, variability and unknowns, Licence term and monitoring requirements. Dwight Grabke, Miramar Northern Mining Ltd. (MNML) Existing Conditions Summary (surface water quality and biological), Golder Future Model Framework and predictions, Effluent Quality Criteria (EQC), link to monitoring, Golder Proposed Surface and Groundwater Monitoring Program, Golder Post-Closure Security Estimate. Dwight Grabke, MNML Post-Closure Monitoring, Working Group, Relinquishment. Dwight Grabke, MNML
Project History 1948 1961 1978 2008 2011 1977 Robertson in-situ water 1941 Bluefish 1952 Acquired 1970 Ceased Shaft max 1983-1989 1937 Construction treatment mid- 1992 Autoclave Hydro Negus Mine roasting depth 1902 m Arsenic Plant 80s, WTP in 1987 (1712MBSL) 2010 - 2011 2007 Closure & On-going 2003 Mining 2004 Milling Sludge Processed 2020 CRP Reclamation Plan 2007 Newmont 2015 New WTP Seasonal WTP Ceased ceased & Autoclave Completed Approved 50+years decommissioned
Reclamation Status • CRP Nearing Completion • Approved Covers in Place • Openings to surface capped • Structural Demolition Complete • Engineered Drainage Channel Network Complete • Vegetation Establishing • Mine workings Continue to Flood
Effluent Quality History Old Effluent Treatment Plant New Effluent Treatment Plant • • 1987 to 2010 New WTP installed in 2015 • • Manual operation (labour-intensive) Automated operation • • Highly variable effluent quality Consistent effluent quality • • Volume of effluent discharged (~1Mm 3 /year) Designed to meet Water Licence and MMER limit for • Discharge up to 170 days per year arsenic • • Volume of effluent discharged (<0.2 Mm 3 /year) As of 2007, no freshwater use for milling • Discharge up to 50 days per year
Source: Silke (2009)
Receiving Environment History • Ore produced until mid-2004, then Mine permanently shut- down • 2007 all operations ceased • Treated discharge to the Meg/Keg/Peg Lake water system since the 1980’s • In the last 10 years, treated discharge occurred in 2007, 2008, 2010 and then in 2015, 2016, 2017 • The water treatment plant operates seasonally, discharging only during the open-water season • The location of final discharge is at the southern extremity of Lower Pud TCA, then drains into a channel that flows into the Meg/Keg/Peg Lake water system • Enters Great Slave Lake at Jackfish Bay
Remaining Closure Tasks & Data Requirements Assessment, Maintenance Vegetative Island Adaptive Vegetation Seed and Acceptance Construction Management, Fertilizer and Monitoring Establish Long-term Monitor Install Monitoring Initiate Active Monitoring & predictions and Minewater Response in 3 System Pumping Management end-points for shafts Controls relinquishment Update Survey Long-term Complete Data, Storage Source water predictions and Middle Pud On-going Water Shoreline Curve, Water synthetic toxicity end-points for Storage Pond Treatment Stabilization Balance, analysis study restoring Natural PMF/PMP drainage Receiving Establish Environment Develop Implement Convene Review realistic Response to Post- monitoring plan monitoring plan yr focused working monitoring results expectations for for approval 1-5 group Closure the system Conditions.
Water Licence Application Summary • 15 year Water Licence • Effluent Quality Criteria set to amended MMER Lower limits for some parameters (arsenic, nickel, cyanide) • Addition of unionized ammonia • Retain pH and hydrocarbons • • Time to monitor, study and evaluate Uncertainties in source water chemistry • Meg-Keg-Peg system (loadings) • How, when, where the application of water quality objectives in Jackfish Bay • A reporting framework - focus on state the environment/comparison to triggers for • further monitoring or investigation • Establishment of a Working Group • Proposed changes to Surveillance Network Program
Closure • Closure Plan, nearing completion, anticipated to be fully complete in 2019-2020. • Licence term is sufficient to assess performance, response, and establish long-term objectives for relinquishment • Some assumptions and uncertainties remain • MNML is committed to the successful remediation of the Con Mine Site and will continue to review monitoring/management practices to ensure long- term success.
Insert Flyover video / site tour
Outline Topics 1, 2 • Receiving Environment History • Existing Conditions • Modelling Framework • Future Conditions • Proposed EQC Topics 3, 4 • Monitoring Topic 5 • Security Topic 6 • Post-Closure
Receiving Environment – Existing Conditions Water quantity • Shallow and sometimes dry (e.g., Meg Lake were not sampled in 2015 and 2010 due to dry conditions) Water quality • Elevated concentrations of TDS and major ions (e.g., chloride and sulphate), and some metals (e.g., arsenic and copper) in M-K-P lakes regardless whether discharge is occurring • Concentrations increase as water flows from Meg to Peg lakes for some parameters (e.g., for chloride >~1000 mg/L) • Mixing provided by Jackfish Bay, but concentrations are still above generic CCME aquatic health guidelines for some parameters (e.g., chloride and arsenic) during periods of no discharge from Con Mine
Meg and Keg Lakes 2003 Downstream view of unnamed stream entering Meg Lake, May 2003. Downstream view of outlet of Meg Lake entering Keg Lake, 2003
Receiving Environment – Existing Conditions Meg Lake July 2015 Keg Lake July 2015
Receiving Environment – Existing Conditions • Surface Water Quality - arsenic temporal trend 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 Arsenic
Receiving Environment – Existing Conditions • Surface Water Quality - chloride temporal trend 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 Chloride
Receiving Environment – 2000 to 2009 Arsenic Chloride
Receiving Environment – Existing Conditions Fish Outlet of Peg Lake • Last sampled in 2015 • No major differences between study fish in Jackfish Bay versus reference areas Benthos • Last sampled in 2015 • Jackfish Bay was different than reference area • It had more benthos and some sensitive species but not as many diverse species • Contaminated sediment is present in the bay; methods to account for this were used Jackfish Bay Flow
Receiving Environment – Existing Conditions Benthos ( con’t ) • Dry areas in 2015 made sampling challenging • More work will be done on benthos in 2018 to confirm why the mid-field area different
Effluent Quality Criteria and Water Quality Management • Propose setting Effluent Quality Criteria to amended MMER lower limits for some parameters (arsenic, nickel, cyanide) • addition of unionized ammonia • Retain pH and hydrocarbons • • MNML is not proposing EQC for ions (chloride, sulphate, TDS) • MNML has investigated waste minimization options for reducing salts. • RO treatment not a viable option for Con Mine (site-specific conditions) due to: Brine waste/concentrates/dust - hazardous • Substantial power requirements • Chemical storage • Scaling, unreliable treatment if influent quality uncertain • Unintended trade-offs (less metals treatment) • Transportation of hazardous waste out-of-province (brine, chemicals) •
Effluent Quality Criteria • Are the Water and Effluent Policy Objectives met? • Based on modelling predictions, MMER limits for metals are protective of water uses in Jackfish Bay (MVLWB Policy Objective #1) MNML proposes the focus be on protection of aquatic life in the far downstream • (i.e., Jackfish Bay) due to the historical loadings of some parameters in the M-K-P system. • MNML has sought continual minimization of waste (MVLWB Policy Objective #2) Constructed a new WTP in 2015 • New WTP designed to meet lower discharge limits in the current Water Licence • MV2007L8-0025, resulted in reduced loadings to the M-K-P lakes system Will meet lower amended MMER limits • RO treatment not a viable option, based on option analysis •
Modelling Framework Developed a modelling framework to simulate concentrations in the receiving environment – existing and future conditions • PHREEQC, GoldSim and CORMIX • Calibrated to existing conditions
Modelling Framework • Calibrated to existing conditions
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