Large Seismic Event Mitigation Zachary Mayer May 24

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Large Seismic Event Mitigation Zachary Mayer May 24 2012

Large Seismic Event Mitigation Zachary Mayer May 24 2012

Agenda • • • What Happened Project Goals and Results Timeline of Geotechnical Studies

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

2009 & 2011 Seismic Events • Jan 6/2009: 3. 8 Mn event on 7000

2009 & 2011 Seismic Events • Jan 6/2009: 3. 8 Mn event on 7000 L. • June 15/2009: 3. 1 Mn event on 7500 L. • Aug 21/2011: 3. 2 Mn event on 7500 L. • Sept 13/2011: 3. 8 Mn event on 7000 L. 3

Seismic Project Goal and Results Determine what happened • Horizontal stress fault slip in

Seismic Project Goal 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. 4

Timeline of Geotechnical Risk Studies and Mitigation Efforts large seismic events 5

Timeline of Geotechnical Risk Studies and Mitigation Efforts large seismic events 5

Ground Control Experts Involved in Kidd Study (2009 -2012) • • • • Patrick

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 Mc. Kinnon – Queens University, Kingston Rob Mercer – Knight Piesold, North Bay Brad Simser – Xstrata Nickel, Sudbury Graham Swan – Ex-Falconbridge, Sudbury Erik Westmin – Virginia Tech, USA 6

Geotechnical Risk Studies Additional Mitigation Efforts 2011 -2012 • Geotechnical analysis through detailed stress

Geotechnical Risk Studies Additional Mitigation Efforts 2011 -2012 • Geotechnical analysis through detailed stress and structural models by 2 different consultants. • Historical sequence modelling back to 2001 to try to recreate and understand events. Stress Model Displacement model Seismic Velocity 7

Risk Mitigation • Enhanced support installation from 6000 L to 9500 L – the

Risk Mitigation • Enhanced support installation from 6000 L to 9500 L – 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. 8

Geotechnical Risk Studies Additional Mitigation Efforts 2011 -2012 • Forensic data mining looking for

Geotechnical Risk Studies Additional Mitigation Efforts 2011 -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. 9

Damage Comparison 2009 vs. 2011 Enhanced Support Works 3. 8 Mn - Jan 2009

Damage Comparison 2009 vs. 2011 Enhanced Support Works 3. 8 Mn - Jan 2009 71 -01 S Complete collapse of back After 2009 rockburst: • 4 intersections collapsed • Drift damaged over hundreds of meters • Several areas inaccessible 3. 8 Mn - Sept 2011 71 -01 S Failure limited to bottom half of walls After 2011 rockburst: • No intersections collapsed • Walls damaged over tens of meters • No areas inaccessible 10

Enhanced Support Works 71 -82 XC enhanced support installed 71 -82 XC after 3.

Enhanced Support Works 71 -82 XC enhanced support installed 71 -82 XC after 3. 8 Mn event 11

7700 L Refuge Station Upgrades 12

7700 L Refuge Station Upgrades 12

7400 L Ramp Upgrades 13

7400 L Ramp Upgrades 13

69 -S 40 ACC Single-Pass Enhanced Support Installed “In Cycle” 14

69 -S 40 ACC Single-Pass Enhanced Support Installed “In Cycle” 14

Modelling Results Example Seismic Potential 2013 Original Mining Plan New Mining Plan Red areas

Modelling Results Example Seismic 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

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? 17