GIANT MINE HUMAN HEALTH AND ECOLOGICAL RISK ASSESSMENT Final Report Prepared by: Canada North Environmental Services Markham, Ontario Prepared for: Public Services and Procurement Canada – Western Region Environmental Services and Contaminated Sites Management 5th Floor, ATB Place, 10025 Jasper Avenue Edmonton, Alberta T5J 1S6 Project No. 2385 January 2018 TABLE OF CONTENTS TABLE OF CONTENTS LIST OF APPENDICES ................................................................................................................. v LIST OF FIGURES ....................................................................................................................... vi LIST OF TABLES .......................................................................................................................... x EXECUTIVE SUMMARY ............................................................................................................. i List of Acronyms .......................................................................................................................... xii Glossary ...................................................................................................................................... xiv 1.0 INTRODUCTION ........................................................................................................... 1 1.1 Definition of a Human Health and Ecological Risk Assessment ................................. 3 1.2 Objective ....................................................................................................................... 3 1.3 Site Description ............................................................................................................. 4 1.3.1 Physical Setting and Surrounding Land Use .......................................................... 5 1.3.1.1 Terrestrial Environment ...................................................................................... 6 1.3.1.2 On-Site Aquatic Environment............................................................................. 7 1.3.1.3 Tailings Ponds and Water Treatment Facility .................................................. 10 1.3.1.4 Off-Site Aquatic Environment (Yellowknife Bay and Great Slave Lake) ....... 11 1.3.2 Site Geology and Hydrogeology ........................................................................... 11 1.4 Summary of Previous Investigations .......................................................................... 13 1.5 Remediation Actions ................................................................................................... 15 1.6 Stakeholder Involvement ............................................................................................ 17 1.7 Scope of Risk Assessment .......................................................................................... 17 2.0 SITE CHARACTERIZATION ..................................................................................... 20 2.1 Review of Existing Site Information .......................................................................... 20 2.1.1 Air ......................................................................................................................... 20 2.1.2 Soil ........................................................................................................................ 21 2.1.2.1 Giant Mine ........................................................................................................ 21 2.1.2.2 Former Townsite ............................................................................................... 24 2.1.2.3 City of Yellowknife .......................................................................................... 25 2.1.2.4 Ndilo ................................................................................................................. 26 2.1.2.5 Latham Island.................................................................................................... 27 2.1.2.6 Ingraham Trail .................................................................................................. 28 2.1.2.7 Fred Henne Campground .................................................................................. 29 2.1.2.8 Dettah ................................................................................................................ 30 2.1.3 Surface Water........................................................................................................ 31 2.1.3.1 Baker Creek ...................................................................................................... 31 2.1.3.2 Yellowknife Bay ............................................................................................... 32 2.1.3.3 Municipal Drinking Water ................................................................................ 33 2.1.4 Sediment ............................................................................................................... 33 2.1.4.1 Baker Creek ...................................................................................................... 34 2.1.4.2 Yellowknife Bay ............................................................................................... 35 2.1.4.3 Long Lake ......................................................................................................... 36 2.1.5 Vegetation ............................................................................................................. 37 2.1.5.1 Aquatic Plants ................................................................................................... 37 PSPC/INAC – January 2018 Giant Mine HHERA i CanNorth TABLE OF CONTENTS 2.1.5.2 Terrestrial Plants ............................................................................................... 38 2.1.6 Animals ................................................................................................................. 39 2.1.7 Fish ........................................................................................................................ 40 2.1.7.1 Whole Body Fish from Baker Creek ................................................................ 41 2.1.7.2 Whole Body Fish from Yellowknife Bay ......................................................... 41 2.1.7.3 Fish Muscle from Yellowknife Bay .................................................................. 41 2.1.7.4 Fish Liver from Yellowknife Bay ..................................................................... 41 2.1.8 Voluntary Sampling Program ............................................................................... 42 2.1.9 Background ........................................................................................................... 48 2.1.9.1 Soil .................................................................................................................... 49 2.1.9.2 Surface Water.................................................................................................... 52 2.1.9.3 Sediment ........................................................................................................... 52 2.2 Constituents of Potential Concern .............................................................................. 53 2.2.1 Constituents of potential concern in soil ............................................................... 54 2.2.2 Constituents of Potential Concern in Surface Water ............................................ 55 2.2.3 Constituents of Potential Concern in Sediment .................................................... 59 2.2.4 Summary ............................................................................................................... 59 3.0 HUMAN HEALTH RISK ASSESSMENT................................................................... 61 3.1 Exposure Locations ..................................................................................................... 61 3.2 Problem Formulation .................................................................................................. 61 3.2.1 Hazard Identification ............................................................................................ 61 3.2.2 Receptor Identification.......................................................................................... 64 3.2.3 Exposure Pathways ............................................................................................... 66 3.2.4 Conceptual Site Model .......................................................................................... 70 3.3 Exposure Assessment.................................................................................................. 71 3.3.1 Fate and Transport Modelling ............................................................................... 72 3.3.2 Receptor Characterization ..................................................................................... 72 3.3.2.1 Country Food Consumption .............................................................................. 73 3.3.2.2 Supermarket Food Consumption ...................................................................... 76 3.3.2.3 Water Intake ...................................................................................................... 76 3.3.2.4 Soil Intake ......................................................................................................... 76 3.3.2.5 Indoor Dust Intake ............................................................................................ 77 3.3.2.6 Sediment Intake ...............................................................................................