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WAIHI SUBSIDENCE ASSESSMENT Summary - Hazard Zones and Cracking Addressed in Report
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| The report is also available from Council Offices and Libraries | Page |
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|
(Cover, Frontispiece and Contents) |
PDF (2.43MB) | PDF (150KB) | ||||
| EXECUTIVE SUMMARY | III | PDF (156KB) | ||||
| 1.0 | INTRODUCTION | 1 | ||||
| 1.1 | Mining Background | 1 | ||||
| 1.2 | Mining Subsidence Review | 1 | ||||
| 1.3 | Previous Reporting | 4 | ||||
| 2.0 | SUBSIDENCE CRATER REVIEW | 5 | PDF (218KB) | |||
| 3.0 | VOID MIGRATION CALCULATIONS FOR NORTH BRANCH, MARY, NO. 2 AND MARTHA STOPES | 6 | ||||
| 4.0 | PEDESTRIAN SAFETY IN WAIHI HAZARD ZONES | 7 | ||||
| 5.0 | GROUND DEFORMATION AT WAIHI | 9 | ||||
| 5.1 | General ground deformation near mines | 9 | ||||
| 5.2 | Terminology | 10 | ||||
| 5.3 | Deformation at Waihi | 10 | ||||
| 5.4 | The types of ground deformation near Martha Mine at Waihi | 11 | ||||
| 5.5 | Recommended Additional Ground Movement Monitoring | 13 | ||||
| 5.6 | Future Ground Movements | 14 | ||||
| 5.6.1 | Estimating the extent of slow (type 4) ground movements | 14 | ||||
| 5.6.2 | Possible extent of long-term ground movements | 15 | ||||
| 5.7 | Possible remote sensing DInSAR monitoring | 15 | ||||
| 6.0 | SUMMARY AND CONCLUSIONS | 18 | PDF (31KB) | |||
| 7.0 | ACKNOWLEDGEMENTS | 19 | ||||
| 8.0 | LIMITATIONS OF THE REPORT | 19 | ||||
| 9.0 | REFERENCES | 20 | ||||
| Figures 5, 5a, 5b | 21 | PDF (476KB) | ||||
| Figures 6, 7, 7a | 24 | PDF (317KB) | ||||
| Figures 8, 9, 10 | 27 | PDF (223KB) | ||||
| Stopes | 30 | PDF (363KB) | ||||
| 10.0 | APPENDICES | 36 | ||||
| Appendix 1 – T W Maton AusIMM Nelson Paper 2004 | 37 | PDF (702KB) | PDF (185KB) | |||
| Appendix 2 – PSM125.L88 report | 40 | |||||
| Appendix 2\PSM125.L88 Rev 1.pdf (9 pages) | PDF (55KB) | PDF (55KB) | ||||
| Appendix 2\PSM125.L88 FIGURE 1.pdf (1 page) | PDF (3.3MB) | PDF (163KB) | ||||
| Appendix 2\PSM125.L88 FIGURE 2.pdf (1 page) | PDF (940KB) | PDF (139KB) | ||||
| Appendix 2\PSM125.L88 FIGURE 3.pdf (1 page) | PDF (339KB) | PDF (339KB) | ||||
| Appendix 2\PSM125.L88 FIGURE 4.pdf (1 page) | PDF (349KB) | PDF (78KB) | ||||
| Appendix 2\PSM125.L88 FIGURE 5.pdf (1 page) | PDF (1.89MB) | PDF (109KB) | ||||
| Appendix 2\PSM125.L88 FIGURE 6.pdf (1 page) | PDF (760KB) | PDF (82KB) | ||||
| Appendix 2\PSM125.L88 FIGURE 7.pdf (1 page) | PDF (710KB) | PDF (81KB) | ||||
| Appendix 2\PSM125.L88 FIGURE 8.pdf (1 page) | PDF (655KB) | PDF (75KB) | ||||
| Appendix 2\PSM125.L88 Attach A part 1.pdf (5 pages) | PDF (2.38MB) | PDF (287KB) | ||||
| Appendix 2\PSM125.L88 Attach A part 2.pdf (5 pages) | PDF (3.12MB) | PDF (349KB) | ||||
| Appendix 3 – Professor Elms 2002 report on Road Safety in Waihi | 68 |
Included in main doc above PDF (2.48MB) |
PDF (115KB) | |||
| Appendix 4 – Remote Sensing Monitoring by Sergei Samsonov, GNS Science | 70 | PDF (593KB) | ||||
| PHOTOGRAPHS & FIGURES | Page | |
| Frontispiece | The iconic Cornish Pumphouse on the move past the end of Gilmour St. to site 4A, late October 2006 | 3 |
| Waihi Photo | Open Pit (centre left) surrounded by Waihi township and the Tailings Ponds on the right. Google Earth image. | ii |
| Photos 1&2 | Cracking in Haszard Street with an unusual north (pit wall) side up and small right lateral component, suggestive of large “block” movement on a through-going rock mass defect. | 2 |
| Photos 3&4 | Cracking in Seddon Street appears to be extensional but also has a small right lateral component of movement in the pavement above. | 3 |
| Photo 5. | Ground cracking due to lateral northward movent and subsidence, evident along the base of the Millenium Wall in Seddon Street, Sept 2008. | 16 |
| Photo 6 | View of surface cracking near the open pit rim which is being monitored with wire extensometers. View looking west. | 17 |
| Photo 6 & 7 | Open ground cracking with north (pit) side up, close to the pit rim and east of the Judges Kauri. | 17 |
| Figure 5a | “Martha” stopes showing detailed sinkhole hazards zones | 22 |
| Figure 5b | Yellow dashed lines show recommended monitoring lines with points at ~20m spacing and incorporating as many existing settlement monitoring points as possible (Figure 7 & 7a). Orange dashed lines are linking lines using existing points. | 23 |
| Figure 6 | Definition of angles of draw and break (As Fig. 41 in the August 2002 GNS report.) | 24 |
| Figure 7 | Total ground settlement contours (orange), settlement values (mm) and survey points, with stopes, shafts and collapses (white) (As Fig. 42 in the August 2002 GNS report.). | 25 |
| Figure 7a. | Existing settlement monitoring points in Waihi with settlement zones due to dewatering. The points are monitored only for vertical movement. Those incorporated in the monitoring lines also need to be accurately surveyed for lateral movement. | 26 |
| Figure 8 | (From Fig. 11 in the August 2002 GNS report.) Cross-section A-A’ through the Royal stopes at the 1999 collapse. Probabilistic hazard zonation is shown illustrating buffer technique employed in this study | 27 |
| Figure 9 | (From Fig. 12 in the August 2002 GNS report.) Cross-section B-B’ through the Royal stopes at the 2001 collapse. Probabilistic hazard zonation is shown illustrating buffer technique employed in this study | 28 |
| Figure 10 | General section through Martha and royal Stopes. | 29 |
| TABLE | ||
| Table 1 | Probability of sinkholes above stopes in Martha, Mary, No 2 and North Branch lodes | 8 |