Con Mine Meg Keg Peg Lake System Study Design Workshop #1 December 10, 2019 Newmont Goldcorp – Confidential I Presentation Name 1 Month YEAR Meg Lake, looking towards Keg Lake, 2017
Workshop Agenda • Welcome and Introductions – MNML and Attendees • Background of Meg Peg Keg (MKP) lakes system - MNML • Goals and Objectives of the MKP Study – MNML and Attendees • Information Requirements to Meet Goals and Objectives – MNML and Attendees • Summary and Wrap-up – MNML Keg Lake looking towards Con Mine, 2015
Welcome and Introductions Purpose of Workshop • Why is MNML completing a study on Meg, Keg and Peg lakes and hosting this workshop? • See Schedule 6 Water Licence Round Table of Introductions • What is your background with Con Mine and/or MKP lake system? • What do you want to get out of or contribute to this workshop? Peg Lake, looking towards YK Bay, 2017
Description of Meg Keg Peg Lakes System Meg Lake with approaching storm, 2019 Newmont Goldcorp – Confidential I Presentation Name 4 Month YEAR
Characteristics of Meg, Keg, and Peg Lakes • Shallow (0.3 to 1 m) and relatively small lakes (0.07 to 0.38 km 2 ) • Local climate, precipitation, and beaver activity affect the water volumes, elevations and water quality in the lakes Sample • Former beaver dam at outlet of Keg, and dam present at outlet of Peg; narrow, marshy channels in between the lakes • Retention time through the system was modelled to be approximately 70 to 200 days, depending on hydrologic conditions Sample Sample Meg Lake, 2015 Meg Lake, 2017
MKP Characteristics – Additional Details Local Drainage Area Lake Cumulative Average Surface Drainage Total Total Watershed Lake Total Land Area Area Depth (a) (m) Water Watershed Area (km 2 ) (km 2 ) Area Area (km 2 ) (km 2 ) (km 2 ) Meg Lake Watershed 0.1 0.3 0.6 0.1 0.6 0.6 Keg Lake Watershed 0.4 1.0 2.2 0.5 2.7 3.3 Peg Lake Watershed 0.1 0.8 1.3 0.1 1.4 4.8 not not 0.4 <0.1 0.4 5.2 Peg Lake Outfall applicable applicable (a) Measured during 2009 survey (Golder 2010) Local watershed boundaries, drainage areas, flow paths and flow connectivity within the MKP lake system were derived from publicly available elevation contour data using GIS tools (GNWT 2014). Due to the coarse resolution (2 m) of the elevation data, the assessment results have a correspondingly reduced accuracy.
Historical Studies and Modelling Historical Studies • Algal and invertebrate communities in three subarctic lakes receiving mine wastes (Moore et al. 1979) • Arsenic transport through the MKP lakes system (Bright et al. 1994, 1996) • Characterization of Arsenic in the effluent drainage basin of Miramar Con Mine, Yellowknife, NWT (William Coedy, 1994) Modelling • 2010, 2018 GoldSim for the MKP lakes system and CORMIX modelling to estimate plume dispersion in Jackfish Bay
Environmental Monitoring Surveillance Network Program (Water Licence) Metal and Diamond Mining Regulations (MDMER/EEM) Aquatic Effects Monitoring Program (Downstream) Supplemental Monitoring for the MKP Study
Water Quality within MKP Lakes System Above CCME aquatic life guidelines for some parameters (Phase 6 EEM Study) • Above chronic CCME aquatic life guidelines for chloride and some metals (e.g., aluminum, arsenic, copper, iron) • Above acute CCME aquatic life guideline for chloride but typically below site-specific acute lethality threshold (2,500 mg/L) • Within CCME pH guideline range and above CCME DO guideline Peg Lake outflow into Jackfish Bay, 2017
Water Quality within MKP Lakes System Variable trends and patterns • Decreases in some parameters (e.g., chloride and ammonia) relative to 2000 to 2004 data • Variable seasonal and spatial patterns such as: • Concentrations of some parameters decrease with distance through the MKP but some increase (e.g., chloride, arsenic) but not at a consistent location depending on the season or year • Seasonal trends for increasing concentrations during the open-water season for TDS and major ions • Concentrations of some parameters are lower in the discharge than in the receiving water at Meg and Keg lakes (e.g., arsenic, copper)
Temporal and Spatial Trends - Chloride, 2000 to 2019 8000 2000-2004 2005 2006 Average Chloride Concentration (mg/L) 2007 6000 2008 2009 2010 2011 2012 4000 2013 2014 2015 2016 2000 2017 2018 2019 (draft) 0 Site
Temporal and Spatial Trends - Arsenic, 2000 to 2019 0.8 2000-2004 2005 Average Total Arsenic Concentration (mg/L) 2006 2007 0.6 2008 2009 2010 2011 0.4 2012 2013 2014 2015 2016 0.2 2017 2018 2019 (draft) 0 -0.2 Site
Current Water Quality - Chloride, 2019 (draft) 2000 May-19 Jun-19 1800 Jul-19 Aug-19 1600 Sep-19 1400 Chloride Concentration (mg/L) 1200 1000 800 600 400 200 0 Site
Current Water Quality - Arsenic, 2019 (draft) 0.8 May-19 Jun-19 0.7 Jul-19 Aug-19 0.6 Sep-19 0.5 Total Arsenic Concentration (mg/L) 0.4 0.3 0.2 0.1 0 Site
Factors Influencing Meg, Keg, Peg Lakes • Climate – drought to Historic Regional Operations record rainfall event • Future Operations / Land and water use by others (off MNML lease) • Current treated effluent • Beaver Dams • Climate Outlet of Meg Lake showing old flood damage to spruce trees Newmont Goldcorp – Confidential I Presentation Name 15 Month YEAR
References Bright, DA, Coedy, B, Dushenko, WT, Reimer, KJ. 1994. Arsenic Transport in a watershed receiving gold mine effluent near Yellowknife, Northwest Territories, Canada. The Science of the Total Environment. Vol 155, pp 237-252. Bright, DA, Dodd, M, Reimer, KJ. 1996. Arsenic in subarctic lakes influenced by gold mine effluent: the occurrence of organo-arsenicals and 'hidden' arsenic. The Scient of the Total Environment. Vol 180, pp 165-182. Golder. 2010. Dispersion of Effluent from Con Mine, Northwest Territories. Technical Memorandum. Project 09-1328-0022/3000. May 2010. Moore, JW, Sutherland, DJ, and VA Beaubien. 1979. Algal and invertebrate communities in three subarctic lakes receiving mine wastes. Water Research. Vol 13, Issue 12, pp 1193-1202.
Goals and Objectives of MKP Study Newmont Goldcorp – Confidential I Presentation Name 17 Month YEAR Peg and Keg lakes looking towards Yellowknife, 2019
Goals and Draft Objectives of MKP Study Overall study goals • Increase our understanding of the MKP lakes system and how it has been influenced in the past to aid in the predictions of the future state under continued use • Make recommendations for future monitoring of conditions in the MKP Draft objectives for discussion • Assess how conditions in the MKP lakes system are influenced by past and ongoing discharges from Con Mine • Assess how conditions in the MKP lakes system will be influenced by future discharges from Con Mine • Recommend on-going post-closure monitoring of the MKP lakes system beyond study period
Information Needs for Discussion Objective Information Available Information Gaps for Discussion • • Assess how Historical toxicity, water quality bathymetry, flow, limnological, water quality conditions in the and sediment quality but not for [surface, porewater], sediment MKP lakes system all years, locations or characteristics and quality data • are influenced by parameters understanding of temporal/spatial patterns • past and ongoing limited biological data in water quality, sediment quality, and • discharges from Con surveys demonstrated no over- benthic invertebrate data • Mine wintering habitat for fish identification of parameters of potential concern • • Assess how GoldSim model built with more accurate and updated loadings conditions in MKP estimates of loadings from estimates for WTP, runoff, seepage, and lakes system will be WTP, runoff, seepage/sediment sediment in GoldSim model • • what changes in MNML’s water influenced by future GoldSim model calibrated at discharges from Con Peg Lake outflow management strategy have the potential to Mine change MKP conditions either positively and negatively? • • Is it appropriate to develop closure “targets” Recommend on- Existing environmental data set going post-closure for the MKP lakes system • monitoring of MKP Is there a suitable analog to monitor as an beyond study period indicator of overall system condition? • What long-term monitoring should continue in the MKP lakes system?
Outline of MKP Study with AEMP/MDMER/EEM for Con Mine
Next Steps for 2020 Q1 Q2 Q3 Q4 Supplementary monitoring in MKP Discussions/planning for collaborative components of study Prepare draft outline of study design Present draft outline at Workshop #2 Update study design Submit MKP Study Design to MVLWB - Dec 1
Thank you for attending! Peg Lake Inlet, 2019 Newmont Goldcorp – Confidential I Presentation Name 22 Month YEAR
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