Recent Secondary Extraction Experience at Cook Colliery in a Multiseam Environment

1. Recent Secondary Extraction Experience at Cook Colliery in a Multiseam Environment William Lawrence Geowork Engineering

2. Castor Seam Workings BBUGS Blackwater February 2011 - Recent secondary extraction experience at Cook Colliery in a multi-seam environment

3. Argo Seam Workings (Castor superimposed) BBUGS Blackwater February 2011 - Recent secondary extraction experience at Cook Colliery in a multi-seam environment

4. N Argo Seam Major Structure BBUGS Blackwater February 2011 - Recent secondary extraction experience at Cook Colliery in a multi-seam environment

5. Lithology BBUGS Blackwater February 2011 - Recent secondary extraction experience at Cook Colliery in a multi-seam environment

6. CMRR – South Argo BBUGS Blackwater February 2011 - Recent secondary extraction experience at Cook Colliery in a multi-seam environment

7. CMRR – North Argo BBUGS Blackwater February 2011 - Recent secondary extraction experience at Cook Colliery in a multi-seam environment

8. North Argo – 305 Panel BBUGS Blackwater February 2011 - Recent secondary extraction experience at Cook Colliery in a multi-seam environment

9. Continuous Haulage System • ABM25 with nominal 5.5 m x 3.8 m roadway profile • Flexiveyor continuous haulage BBUGS Blackwater February 2011 - Recent secondary extraction experience at Cook Colliery in a multi-seam environment

10. Roadway Development Authority To Mine BBUGS Blackwater February 2011 - Recent secondary extraction experience at Cook Colliery in a multi-seam environment

11. Trigger Action Response Plan (TARP) BBUGS Blackwater February 2011 - Recent secondary extraction experience at Cook Colliery in a multi-seam environment

12. Method of Secondary Extraction BBUGS Blackwater February 2011 - Recent secondary extraction experience at Cook Colliery in a multi-seam environment

13. Strata Conditions After Sumping BBUGS Blackwater February 2011 - Recent secondary extraction experience at Cook Colliery in a multi-seam environment

14. Pillar Design Primarily Empirical Numerical modelling also required for certain situations Odd shaped pillars Castor abutment Extent of roof falls Relatively simple models are usually sufficient • UNSW empirical pillar strength formulation • Minimum remnant pillar FoS of 1.5 • Fenders do not contribute to pillar strength • Assume pillar side has been stripped • Fender stability can not be assessed using this empirical formula BBUGS Blackwater February 2011 - Recent secondary extraction experience at Cook Colliery in a multi-seam environment

15. Displacement Discontinuity Numerical Modelling (LaModel) Vertical pillar stress with no overlying Castor workings Vertical pillar stress with overlying Castor workings BBUGS Blackwater February 2011 - Recent secondary extraction experience at Cook Colliery in a multi-seam environment

16. Finite Element Numerical Modelling (Phase2) BBUGS Blackwater February 2011 - Recent secondary extraction experience at Cook Colliery in a multi-seam environment

17. Fender and Roadway Stability General comments Sumping can be done under poor roof conditions if primary support is installed to TARP standard This includes fault-affected strata and Castor abutment However, sump spacing is increased under known faults and Castor abutment Some areas are just avoided! Cleat orientation does affect fender stability Generally, a “double-whammy” is avoided, e.g. fault and Castor abutment Falls may occur in unsupported sumps BBUGS Blackwater February 2011 - Recent secondary extraction experience at Cook Colliery in a multi-seam environment

18. Sump Spacing (Fender Width) Design BBUGS Blackwater February 2011 - Recent secondary extraction experience at Cook Colliery in a multi-seam environment

19. Secondary Extraction Roof Stability Issues Sump spacing design chart is a hybrid empirical and numerical method based on Cook experience. Yes, there has been inbye supported roadway roof falls of no consequence before it became an issue. These provide excellent data points. Even with the design chart there is no guarantee of inbye roadway stability after secondary extraction. Additional coal is being taken without supplementary support. Argo roof is relatively weak. Stability around the current sump must be ensured, and protocols (TARP) are in place for this. The crew must not take or complete a sump if conditions change. BBUGS Blackwater February 2011 - Recent secondary extraction experience at Cook Colliery in a multi-seam environment

20. Recent KM02 Roof Falls BBUGS Blackwater February 2011 - Recent secondary extraction experience at Cook Colliery in a multi-seam environment

21. KM02 C16/17 Fall BBUGS Blackwater February 2011 - Recent secondary extraction experience at Cook Colliery in a multi-seam environment

22. KM02 D19/20 Fall BBUGS Blackwater February 2011 - Recent secondary extraction experience at Cook Colliery in a multi-seam environment

23. Sump widthMRSCavingSealed Castor workingsFLAC3D BBUGS Blackwater February 2011 - Recent secondary extraction experience at Cook Colliery in a multi-seam environment

24. FLAC3D model BBUGS Blackwater February 2011 - Recent secondary extraction experience at Cook Colliery in a multi-seam environment

25. First workings in Argo Seam – 6 m roadway BBUGS Blackwater February 2011 - Recent secondary extraction experience at Cook Colliery in a multi-seam environment

26. Secondary extraction – 4 m sump and 7 m fender BBUGS Blackwater February 2011 - Recent secondary extraction experience at Cook Colliery in a multi-seam environment

27. Secondary extraction – 16 m sump/strip with 8 m fender BBUGS Blackwater February 2011 - Recent secondary extraction experience at Cook Colliery in a multi-seam environment

28. First workings in Argo Seam beneath Castor roadways BBUGS Blackwater February 2011 - Recent secondary extraction experience at Cook Colliery in a multi-seam environment

29. Secondary extraction – 16 m sump/strip with 8 m fender BBUGS Blackwater February 2011 - Recent secondary extraction experience at Cook Colliery in a multi-seam environment