Large Seismic Event Mitigation

1. Large Seismic Event Mitigation Zachary Mayer May 24 2012

2. Agenda • What Happened • Project Goals and Results • Timeline of Geotechnical Studies • Risk Mitigation • Ground Support Standards • Geotechnical Modelling Results

3. 2009 & 2011 Seismic Events • Jan 6/2009: 3.8 Mn event on 7000L. • June 15/2009: 3.1 Mn event on 7500L. • Aug 21/2011: 3.2 Mn event on 7500L. • Sept 13/2011: 3.8 Mn event on 7000L.

4. Seismic ProjectGoal and Results • Determine what happened • Horizontal stress fault slip in pillar. Structure & geometry. • Can seismic models reproduce the events? • Yes – now have a better understanding. • Can we control the events? • New mining sequence will not eliminate seismic events, but should reduce maximum magnitude going forward. • Can we manage the impact of large events? • Yes - New support standards are effective in reducing damage/risk. Additional reinforcement in key areas. • Re-entry protocols. Expanded the post-blast closure areas and increased personnel re-entry times.

5. Timeline ofGeotechnical Risk Studies and Mitigation Efforts large seismic events

6. Ground Control Experts Involved in Kidd Study (2009-2012) • Patrick Andrieux – Itasca Consulting, Sudbury • David Beck – Beck Engineering, Australia • Wilson Blake – Independent Consultant, USA • Richard Brummer – Itasca Consulting, Sudbury • John Fedorowich – Itasca Consulting, Sudbury • Anneta Forsythe – ex-Kidd/Itasca now Vale, Sudbury • John Henning – ex-Kidd now Goldcorp, Timmins • Marty Hudyma – Laurentian University, Sudbury • Steve McKinnon – Queens University, Kingston • Rob Mercer – Knight Piesold, North Bay • Brad Simser – Xstrata Nickel, Sudbury • Graham Swan – Ex-Falconbridge, Sudbury • Erik Westmin – Virginia Tech, USA

7. Geotechnical Risk Studies Additional Mitigation Efforts2011-2012 • Geotechnical analysis through detailed stress and structural models by 2 different consultants. • Historical sequence modelling back to 2001 to try to re-create and understand events. Stress Model Seismic Velocity Displacement model

8. Risk Mitigation • Enhanced support installation from 6000L to 9500L – the PPE of the mine. • Re-entry protocols. Expanded the post-blast closure areas and increased personnel re-entry times. • Currently shutting down between 2-4 levels for 12+ hours approximately 140 times/year. • Revised mining sequence. • Revised support standards (lower screen & bolt to floor). • Six Sigma project– single-pass “in cycle” enhanced support. • Ongoing monitoring for deviation - SMART cable installation in intersections.

9. Geotechnical Risk Studies Additional Mitigation Efforts2011-2012 • Forensic data mining looking for correlations. • Confirming and adjusting ground support in damaged areas. • Additional cable bolting in sensitive areas. • Instrumenting more intersections. • Investigating new seismic monitoring technology. • Passive seismic tomography study. • Additional microseismic system upgrades.

10. Damage Comparison2009 vs. 2011Enhanced Support Works 3.8Mn - Sept 2011 71-01S 3.8Mn - Jan 2009 71-01S Failure limited to bottom half of walls Complete collapse of back • After 2011 rockburst: • No intersections collapsed • Walls damaged over tens of meters • No areas inaccessible • After 2009 rockburst: • 4 intersections collapsed • Drift damaged over hundreds of meters • Several areas inaccessible

11. Enhanced Support Works 71-82 XC enhanced support installed 71-82 XC after 3.8Mn event

12. 7700L Refuge Station Upgrades

13. 7400L Ramp Upgrades

14. 69-S40 ACCSingle-Pass Enhanced Support Installed “In Cycle”

15. Modelling Results ExampleSeismic Potential 2013 Original Mining Plan New Mining Plan Red areas represent potential seismic zones

16. Conclusion • New technology and tools provided better analysis and planning information. • Have modelled that we can do something different - new mining sequence reduces risk. • Expert consensus obtained on path forward. • Enhanced support is doing it’s job. • Expanded re-entry protocols keeping people out of harms way. • Questions?