EVOLUTION OF RECLAMATION FOR WILDLIFE HABITAT AT SULPHIDE MINES IN BRITISH COLUMBIA, CANADA. Natalie Tashe November 9, 2012

Transcription

1 EVOLUTION OF RECLAMATION FOR WILDLIFE HABITAT AT SULPHIDE MINES IN BRITISH COLUMBIA, CANADA Natalie Tashe November 9,

2 GEOGRAPHIC CONTEXT 2

3 DEFINING WILDLIFE HABITAT 3

4 OUTLINE 1. Mine Cycle for reclamation and ARD/ML 2. Examples of Mining Practices from the Past to Current Best Management 3. Innovative Trends in Reclamation (wildlife habitat restoration and ARD Management) 4. Summary of Synergies and Limitations for Restoring Wildlife Habitat at Sulphide Mines 5. Acknowledgements/Questions 4

5 UNDERSTANDING THE MINE CYCLE From ICMM Planning for Integrated Mine Closure: Toolkit 5

6 DEVELOPMENT OF MINE CYCLE APPROACH LIFECYCLE PLANNING From ICMM Planning for Integrated Mine Closure: Toolkit 6

7 GOOD PRACTICE AND POOR PRACTICE PLANNING Mine Phase Good Practice Poor Practice Risks for Restoring Habitat Exploration Pre-feasibility Feasibility Establish baseline and reclamation of disturbance Develop preliminary mine design models and conceptual reclamation address ARD in mine design and models Cost out reclamation for suitable bonding and costing that accounts for timeline for water mgmt./treatment if ARD/ML Inadequate measures to protect environment (e.g. erosion control) Insufficient planning Insufficient bonding Understanding baseline for Wildlife Habitat Achieving Land Use Targets Predicting Post Closure Landscape 7

8 GOOD PRACTICE AND POOR PRACTICE IMPLEMENTATION Mine Phase Good Practice Poor Practice Risk for Restoring Habitat Construction Operations Salvage of suitable capping material. Water management structures in place Progressive reclamation and waste rock design that allows for on-going reclamation Insufficient salvage of material, water not properly managed (e.g. seeps) Reclamation only at closure Wildlife habitat recovery Delays and Limits Reclamation 8

9 GOOD PRACTICE AND POOR PRACTICE ON-GOING MONITORING Mine Phase Good Practice Poor Practice Risks for restoring Habitat Decommissioning Closure Post-closure Keeping necessary infrastructure in place to manage ARD (e.g. groundwater interception wells) adjust monitoring Final reclamation with knowledge and research from operations Monitoring for both ARD/ML and reclamation for reclamation minimum is 5 years Insufficient water mgmt. and monitoring Lack of adaptive mgmt. Uptake of metals in high concentrations of revegetated areas or areas that are unsuitable for reclamation Delays ability to restore wildlife habitat New issues e.g. Waste rock toe failure Areas of mine may remain unsuitable for wildlife habitat e.g. tailings impoundments 9

10 EXAMPLES OF RECLAMATION PRACTICES Five sulphide mine examples in British Columbia Wildlife habitat is the end land use objective of the five mines 10

11 PRACTICES FROM THE PAST TOWARDS THE FUTURE 11

12 PRACTICES FROM THE PAST TOWARDS THE FUTURE PRACTICES FROM THE PAST Practices from the past (pre-1980s): Poor understanding of environmental effects at mine closure Mining was economics driven, with less emphasis and understanding on the environment Reclamation and ARD/ML science was in its infancy (and it is still evolving) 12

13 PRACTICES FROM THE PAST TOWARDS THE FUTURE PRACTICES FROM THE PAST Waste Rock: no segregation of PAG/NAG, used available material to build roads/dams Water, dilution is the solution Over confidence in we will figure it out at operations No or little consideration of wildlife habitat objectives until end of mining 13

14 PRACTICES FROM THE PAST TOWARDS THE FUTURE CASE STUDY: LESSON LEARNED Equity Silver Operated an open pit mine and for the last three years of operation worked underground. Mine operated between 1980 to 1994 and mined copper, silver and gold History ARD issues on site Waste rock used in Mine infrastructure (mix of NAG/ PAG-ARD in dams, road construction) 14

15 PRACTICES FROM THE PAST TOWARDS THE FUTURE CASE STUDY: LESSON LEARNED Present Currently managing ARD with cover design on waste rock, tailings management with water cover Equity Silver Mine Water Treatment Plant will run in perpetuity bonding went from $5 million to $50 million Extensive monitoring and adaptive management plan in place. These measures provide a learning tool for other sulphide mines around the world Wildlife Habitat values are now being restored on site in some areas may not represent average baseline conditions 15

16 DEVELOPMENT OF MINE CYCLE APPROACH PLANNING FOR CLOSURE Key learning to meet end land use objectives of wildlife habitat: Questions regarding Reclamation and Closure, ARD/ML are best dealt with sooner rather than later Health, Safety and Reclamation Code for Mines in British Columbia 2008 Guidelines For Metal Leaching and Acid Rock Drainage at Mine sites in British Columbia published in

17 DEVELOPMENT OF MINE CYCLE APPROACH PLANNING FOR CLOSURE Key learning to meet end land use objective of wildlife habitat: Mine Design: incorporating environmental mitigations ARD/ML plays a role in reclamation Closure Planning: part of the feasibility, construction and operations influences post closure outcome 17

18 CURRENT BEST MANAGEMENT MINING PRACTICES RECLAMATION PLANNING Good understanding of pre-development environmental conditions (baseline) Emphasis on attaining average wildlife capability compared to baseline Life cycle approach emphasis on planning for closure 18

19 PRACTICES FROM THE PAST TOWARDS THE FUTURE CASE STUDY: PLANNING Samatosum pre-planning in early stages post 1980s Mine operated from 1989 to 1992 to extract silver, lead zinc and copper ARD issues were known pre-development Measures were taken to plan for ARD and for wildlife habitat ABA calculations, segregated waste rock, designed tailings, and waste rock piles, appropriate capping material salvaged 19

20 PRACTICES FROM THE PAST TOWARDS THE FUTURE CASE STUDY: PLANNING Samatosum (cont d) M-184, October 20,1989 Land Use: The surface of the land and watercourses shall be reclaimed to the following land use: commercial timber, grazing and wildlife habitat 20

21 PRACTICES FROM THE PAST TOWARDS THE FUTURE CASE STUDY: PLANNING Samatosum (cont d) Permit requirements for vegetation M-184, Section 3, July 5, 2006 Metals in Vegetation: Vegetation shall be monitored in 2006, and every five years thereafter, for heavy metal uptake to allow assessment of potential effects on wildlife 21

22 PRACTICES FROM THE PAST TOWARDS THE FUTURE CASE STUDY: PLANNING Samatosum (cont d) Reclamation research , implementation Monitoring metal uptake summary for five years most elements within normal range of tolerances for beef cattle Despite the measures taken to plan for ARD, water treatment is required 22

23 PRACTICES FROM THE PAST TOWARDS THE FUTURE CASE STUDY: PLANNING ARD/ML issues arose from pit, low grade ore stockpile and the seeps in the WR pile, measures were taken to treat water at closure. How did this ARD issue affect reclamation? Unable to fully reclaim areas where water treatment facilities are located, no reclamation around water collection pond (surge pond), and capping and reclamation trials taking place for sludge Forested ecosystem surrounding tailings water quality safe, but dam cannot support habitat value due to stability water cover - reclamation used to preserve the embankment cat tails planted to maintain dam 23

24 CURRENT BEST MANAGEMENT MINING PRACTICES RECLAMATION MONITORING Current best mining practices Monitoring throughout the mine life to find trends and triggers for potential challenges (e.g., metal uptake in vegetation from soils) Monitoring and adaptive management while operational 24

25 PRACTICES FROM THE PAST TOWARDS THE FUTURE CASE STUDY: MONITORING Premier Gold Project Operated periodically since 1917 declared closed in 2002 Potential ARD is predicted from early trials, but not a current issue on site Permit text for habitat M-179 Land Use: (a) The land surface shall be reclaimed to an end land use that considers previous and potential uses. (b) The proposed final end land use as wilderness habitat is approved. The waste rock dumps, pits, roads and plant site areas shall be reclaimed to a deciduous forest forming wildlife habitat. The tailings impoundment shall be reclaimed to a partial wetland, open water wildlife habitat. 25

26 PRACTICES FROM THE PAST TOWARDS THE FUTURE CASE STUDY: MONITORING Premier Gold Project (cont d) Closure support activities: Predictive Water Management Model developed to support closure planning, such as source loads from mine infrastructure. Trends and 18 years of data incorporated in model calibration 26

27 PRACTICES FROM THE PAST TOWARDS THE FUTURE CASE STUDY: MONITORING Premier Gold Project (cont d) Tool to assess ecological impact Monitoring of vegetation and soils to confirm no areas are going acid or issues with metal uptake Intensified monitoring program surrounding watershed impacted by waste rock dumps to verify trends to support closure metal leaching decreasing, ph neutral/near alkaline 27

28 CURRENT BEST MANAGEMENT MINING PRACTICES RESEARCH AND DEVELOPMENT Current best mining practices Research trials and progression of reclamation for wildlife habitats Learn from previous mining operations mine operators meet and share ideas, always improving 28

29 PRACTICES FROM THE PAST TOWARDS THE FUTURE CASE STUDY: ADDRESSING ARD AND RECLAMATION Kitsault Is a molybdenum mine located on the northwest British Columbia coast Operated intermittently from 1968 until 1982 reclamation trials began in the 1970s 1996 final mine reclamation began with plan, decommissioning and site preparation for revegetation 2006 final phase of reclamation completed in the Pit /Central core. Last area reclaimed to address ARD issues Substation Lay down area 1996 Concentrator building Fine ore bins Coarse ore bin Primary crusher Secondary crusher Primary crusher

30 PRACTICES FROM THE PAST TOWARDS THE FUTURE CASE STUDY: ADDRESSING ARD AND RECLAMATION Kitsault (cont d) M-10 Land Use: The reclamation performed on the waste rock dumps, pit floor, roads, and plant site areas shall be monitored to verify that these areas have been reclaimed to deciduous forests forming wildlife habitat 30

31 PRACTICES FROM THE PAST TOWARDS THE FUTURE CASE STUDY: ADDRESSING ARD AND RECLAMATION Kitsault (cont d) ARD issues of the pit central core involved installation of liners, use of limestone, drainage channels and overburden capping. All ARD on site currently addressed slightly alkaline water/veg. metals stable (Ca, Mo, Ba, Cd) Linkage to ARD/ML Capping material was a limited resource on site and could not be used for all reclamation sites. Capping was used to cover ARD sites predominantly Current mine design and future closure plan is integrating lessons learned from past reclamation work performed on site 31

32 INNOVATIVE TRENDS 32

33 INNOVATION IN MANAGING ARD AND PROMOTING RECLAMATION Cover design innovations and maintaining wildlife values. Water management and water treatment improving water quality to create wildlife habitat on mine sites Building a larger body of research sharing experiences from the past and adopting or improving (e.g., water treatment passive wetlands to tailings design) Integrated Life of Mine plan working groups with mine engineers, geochemists and reclamation 33

34 PRACTICES FROM THE PAST TOWARDS THE FUTURE CASE STUDY: INNOVATION Mount Washington Abandoned mine site on Vancouver Island Copper mine operated ARD issues Innovation: capping with geo membrane and reclamation cover design 34

35 PRACTICES FROM THE PAST TOWARDS THE FUTURE CASE STUDY: INNOVATION Mount Washington (cont d) Abandoned site had unsuccessful revegetation due to low ph of the waste rock piles Low ph were affecting salmon in the nearby Tsolum River Started the Tsolum River Society Gov t, NGOs, mining and forest industry secured funding First step: Preparation and capping of site 35

36 PRACTICES FROM THE PAST TOWARDS THE FUTURE CASE STUDY: INNOVATION Mount Washington (cont d) Second Step: Design of water ways minimize flows through waste rock linkage to reclamation in some areas only grass layer applied due to protection of cover Third Step: Innovation in reclamation Creation of micro habitats such as wetlands, coarse woody debris, tree planting and wildlife vegetation corridors 36

37 PRACTICES FROM THE PAST TOWARDS THE FUTURE CASE STUDY: INNOVATION Mount Washington (cont d) Fourth Step: Monitoring salmon are recovering Within first year good cover design and reclamation turned down the tap of ARD resulting in improvements to the Tsolum River watershed 37

38 SUMMARY ARD/ML and Reclamation do have connections Poorly managed ARD can limit the success of restoring wildlife habitat plants will not grow in low ph, and risk for metal uptake to plants Capping for ARD/ML in some instances dictates the wildlife habitat formed (grass versus trees) In some instances, improvements in ARD/ML management has resulted in improvements to reclamation by increasing the rate at which reclamation can start progressive waste rock piles = progressive reclamation Wildlife habitat can be restored on sulphide mines 38

39 ACKNOWLEDGEMENTS The authors are grateful to Equity Silver, INMET, Premier Gold, Tsolum River Society, Teck and Avanti Mining Inc. for permitting the use of photos and reports for this presentation. In addition, thanks to Peter Healey and SRK for the use of Kitsault and Mount Washington reports and power point presentation materials. 39