Reclamation and Closure Cost Planning and Estimation and the Mining Life Cycle. Presenter: Lois Boxill, P.Eng., P.E.

Transcription

1 Reclamation and Closure Cost Planning and Estimation and the Mining Life Cycle Presenter: Lois Boxill, P.Eng., P.E.

2 Overview Preludes to Closure Cost Estimation Reclamation and the Mining Life Cycle Public Perception Observed Closure Cost Estimation Practice Proactive Reclamation and Closure Cost Planning A Case Study: The Kemess Tailings Dam Closing Remarks

3 Cost Estimation Preludes Provide 3rd party quantities and cost estimate for reclamation & closure Initial scopes presented as limited with client requesting numbers update from consultant Numbers to be included in the updated for client submittals Clients may initially indicate responsibility for determining: Long-term WQ monitoring costs Vegetation costs All structural demolition costs

4 Closure Cost Estimation Preludes (continued) Key Questions must be asked: What is the big picture and where are these numbers being used? What constitutes a 3 rd party independent deliverable? Are key pieces of info missing? How might our knowledge of the bigger picture translate into more effective client service? - The devil is always in the overlooked/trivialized details.

5 Reclamation Planning and the Mining Life Cycle BONDING Claim Staking & Exploration EA Process Feasibility Studies Permitting Design - Monitoring (Initial RCP) Development, Production, Progressive Reclamation FUNDING REQUIRED CAPITAL EXPENDITURE Min. Production Cost + Favorable Market = Profit Stream Development Reclamation and Closure Long-term monitoring

6 Reclamation and the Mining Life Cycle (continued) Knowns: Some aspects can be done progressively often with financial incentives Must be planned for Costs money potentially lots of it!! Can t be avoided Bonding is means by which the government tries to minimize its headache and make companies liable for project impacts Regulatory bond reviews can be beneficial Yet some clients would still rather delay a detailed look but too long a wait often results in an unhappy fate!!

7 Reality Clients typically have clear ideas about closure issues and possible closure measures Failure to comprehensively/routinely update RCPs & estimates Annual reporting to regulatory agencies tends to focus on: 1. Meeting water quality thresholds 2. Demonstrating limitation of disturbed areas & focus on reforested land 3. Trying to demonstrate responsible management of any ARD issues Potential problems of metal leaching or adequate allocation of funds for potentially large Civil Works costs can remain Failure to appreciate implications of time horizon for being on the hook Result: True magnitude of reclamation and closure cost liabilities are often unknown externally and internally!!

8 Public Perception Source: National Resources Defense Council (Sept. 2007)

9 Observed Closure Cost Estimation Practice Initially weighted according to client s opinion of estimate drivers Frequently Overlooked Costs/Closure Considerations: Long-term monitoring and reporting for water quality (Ground and Surface monitoring) Long-term species/environmental monitoring Inspection visits and remote monitoring Thorough assessment of long-term treatment requirements (ARD/ML considerations) Engineering Design Costs Establishing sustained vegetation (wetland and dry land species based on specific site end land use objectives ) Maintenance/Repair (site access, dam repair) Quarry Development/Drainage Material Development Crushing, screening, blending Rock excavation, blasting, & concrete/grout

10 Proactive Reclamation and Closure Cost Planning Case Study: Kemess Mine Tailings Dam Open Pit TDF Existing Creek Main NAG Waste Dump PAG Waste Piles Airstrip FW Diversion

11 Kemess Tailings Dam Low permeability clayey till core (Height: >140m; Width: >1km) 4m freeboard to store design event (24-hr PMP w/ 1:100 snowmelt; peak inflow to reservoir m 3 /s) Construct permanent spillway channel & rip rap chute (33m 3 /s) Construct diversion channels to route water away from toe dam and to manage avalanche runout on to dam Need to disk in growth media (0.3m min.) into D/S slope, crest, and beach Need to establish sustained (but non dam damaging) vegetation on downstream slope, crest and beach ~40ha to be vegetated Original estimate in 1999 RCP - $1M 2007 $CDN >$12.7M (Spillway alone - $6M)

12 Kemess Tailings Dam (Spring 2006) Seepage Recycle Pond Sediment Collection Pond

13 Kemess Tailings Dam (Spring 2007) Chute length 1.6km (2.2km total) 180 m drop

14 Closure Diversion Ditch Installation Avalanche Capture Area Dam Adjacent Area R1 Bench Area Borrow 7 Area

15 Avalanche Capture Area (Spring 2007)

16 Avalanche Capture Area (Summer 2008) D D6 8 minus G1 2 minus

17 Other Ditch Sections Dam Adjacent Area Bench Area Secondary Ditch Section

18 Drainage Swales

19 Progressive Reclamation Beach Development 15,550E Good short and longterm dam stewardship 15,450E

20 Reclamation Media Placement (Summer 2008) Est. Price tag: ~$0.5M+ (But covered under operations budget)

21 Kemess Tailings Dam (Summer 2008)

22 Concluding Remarks The Closure Plan and Closure Estimate are dynamically linked and are living documents Risk management throughout mine life pays off Numbers typically: translate into costs and costs drive the mining machine evoke a reaction from share holders/stock price No such thing as a simple cost estimate Costs could mean the initiation of a mining for closure scenario Good record keeping is key! Material characterization, staging, and construction records Knowledge of RCP commitments is important Source: BC Technical & Research Committee on Reclamation

23 Concluding Remarks (continued) Liabilities of estimate preparation and reliance must be appreciated Design for closure: Waste rock dumps with benches to minimize resloping costs; Material staging is important Bio-remediation technologies Water management Consistency between engineering design and closure objectives and vice versa A proactive vs. reactive exercise Estimate underestimation is in nobody s best interest! Proactivity can include: Teaming with project stake holders Research center partnering to test proposed closure measures and develop technologies to shorten closure window (e.g. vegetation suitability, soil amendments, covers etc), water quality/management modeling etc.

24 Questions/Comments? Thank You.