Spatial positioning of sidewall stations in a narrow tunnel environment: a safe alternative to traditional mine survey practice.

Spatial positioning of sidewall stations in a narrow tunnel environment: a safe alternative to traditional mine survey practice.

Hendrik Christoffel Ignatius GroblerA thesis submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy.Johannesburg, 2015

Declaration page

I declare that this thesis is my own unaided work. It is being submitted to the Degree of Doctor of Philosophy to the University of the Witwatersrand, Johannesburg. It has not been submitted before for any degree or examination to any other University.

Signature of H.C.I. Grobler

24thth day of April 2015

Abstract

This thesis proposes an alternative method of mine surveying in order to improve the safety and accuracy of primary survey network control in a narrow tunnel environment. It is argued that the traditional South African practice of establishing survey networks in the roof of a tunnel, although accurate, is time consuming and increases the risk exposure of survey crews. In the South African mining context Health and Safety legislation requires managers to take every precaution to ensure the health and safety of their employees. It is argued that current developments in survey technology can provide a safe and accurate alternative of establishing primary survey networks.

A method of establishing a primary network in the sidewall of a tunnel was tested under controlled conditions and evaluated under real working conditions. It was found that the accuracy of such a sidewall survey network can meet the defined accuracy requirements of the Mine Health and Safety Act, provided that specific geometric configurations are met and certain observation protocols are followed. A detailed risk analysis of the effect of external factors on the accuracy the network and the health and safety of workers was made. A standard practice was developed to mitigate the identified risks in the installation and maintenance of such a sidewall survey network. This thesis recommends that under specific conditions, a sidewall survey station network can provide first, a safe and accurate alternative to traditional mine survey networks and second, provide the required control for accurate setting-out surveys in a three-dimensional environment .

Acknowledgements

For Suretha and Alannah.

The author wishes to express his sincere appreciation to Professor Cawood for his support and assistance in the preparation of this manuscript. In addition, the author would like to extend his sincere gratitude to Ben van Staden, Angus Miller, Calvin Tijane, Wilson Kobe, Carel Roos, John McCaffery, Johan Bezuidenhout, Chanren Leung, David Wilson, Peter Knottenbelt, Donovan Anderson and Professor Antoine Bafabundi-Mulaba.

Table of ContentsAbstract Table of ContentsiiList of figuresxiiList of tablesxvChapter 1 Introduction11.1.Mine surveying an overview21.2.The formulation of the fundamental question101.3.The research outline111.4.Overall objectives121.5. Methodology131.6. An overview of the literature search and further chapters15Chapter 2 Regulations, Standards and Codes of Practice192.1.The South African Legislative Environment192.1.1. Major contributors to injuries and Fatalities in the South African mining industry232.2. Recent Mine safety incidents related to mine surveying242.2.1.The Gretley Coal Mine Disaster242.2.2.Beaconsfield Mine 25 April to 9 May 2006252.2.3.The Chilean Mine Rescue262.3.An Overview of relevant standards of accuracy.272.3.1.The Mine Health and Safety Act; 1996 (Act 29 of 1996)272.3.2 The Land Survey Act, 1997 (Act No 8. of 1997)332.3.3 Federal Geodetic Control subcommittee (FGCS), Part 4, USA352.3.4. Positional accuracies for primary control systems (ISO4463)372.3.5.Intergovernmental Committee on Surveying and Mapping (ICSM SP1.7)382.3.6.Canadian Survey Standards, General Instructions for Surveys, e-Edition, Appendix E4 Accuracy standard for legal surveys392.3.7.The Institute of Mine Surveyors of South Africa: Guidelines for standard Mine Surveying practice402.3.8.Department of Industry and Resources, 2005, Mines survey - Code of practice: Safety and Health Division, Department of Industry and Resources, Western Australia422.3.9.Survey and Drafting Directions for Mine Surveyors 2007 (New South Wales Coal)432.3.10.Limits of error defined in the Tunnelling industry442.4.A Comparison of Minimum standards of accuracy462.5.Mining house corporate standards of accuracy492.6. Other Corporate Safety Standards and Procedures502.6.1.The Occupational Health and Safety Act of New South Wales532.6.2. The BHP Divisional Standard Procedure542.6.3. The Anglo American Fatal Risk Standards: Working-at-heights562.7. Working at heights and the associated risks562.8. The effect of external factors on the accuracy of a survey network602.8.1. Illumination612.8.2The effect of refraction622.8.3. Visibility in the underground environment.702.8.4. The interference of ventilation722.8.5. The height of workings732.8.6. Poor ground conditions742.8.7. Moving Machinery762.8.8. Production pressure762.9. Summary of the findings in this chapter79Chapter 3 Surveying Technology Review823.1.Technological advances in Instrumentation823.2.Electronic Distance Measuring technology873.2.1 Electronic recording and data collection873.2.2On-board and post-processing software883.3.A review of traditional mine surveying methods893.4.Conventional Surveying methods923.4.1.Traversing923.4.2.Intersection943.4.3.Triangulation953.4.4.Trilateration963.4.5.Resection973.4.6.Vertical Resections993.4.7.Freestations1003.4.8.Three-dimensional two-point resection1023.4.9.Triangulateration1023.5. The geometry of observations1043.5.1. The effect of redundant measurements1063.5.2. The minimum number of observations1073.6.Error propagation1093.6.1.Sources in error in running a traverse1103.7.Alternative surveying techniques1113.7.1.The Three Spad Method1123.7.2.The Random Transit Method1123.7.3.Grade pegs in concrete Piers1143.7.4.Central European Survey methods1153.7.5.Wall Markers1153.7.6.Australian Wall Stations1163.7.7.The Grade-peg method1173.7.8.The JCI method of co-ordinated sidewall pegs1183.8. Tunnel surveying1193.8.1.The Zigzag method1193.9. Typical Tunnelling Network layouts1223.9.1.Diamond Light Source tunnel, Rutherford Appleton Laboratory, Oxfordshire1233.9.2.Euro Channel Tunnel1233.9.3.Fermilab Main Injector ring1243.9.4.Hong Kong tunnel Construction1243.9.5.Lane Cove Tunnel, Sydney, Australia1253.9.6.Japanese tunnel construction1253.9.7.Project Hallandsas, Sweden1263.9.8.Superconducting Super Collider , Waxahachie, Dallas , USA1263.9.9.Synchotron Radiation Source1273.9.10.Uetliberg tunnel, Zurich Western Bypass1281283.10. Summary of the findings in this chapter1281283.10.A comparison of survey methods using AHP1311313.11.Proposed survey network to be established for the test phase136136Chapter 4 . Set up of the hangingwall control network1381384.1.Introduction1381384.2.Establishment of the control network1421424.2.1.Check Survey1431434.2.2.Bearing Check1461464.2.3.Elevation check1461464.2.4.Instrument used1471474.2.5.Instrument Settings1471474.2.6.Barometric pressure1481484.2.7.Temperature1521514.2.8.Final Settings1521514.3.Required Standard of Accuracy1531524.3.1.Interpretation of the MHSA Regulation 17(14)1541534.4.The traditional hangingwall survey method1551544.5.The closed traverse1581574.5.1.Gyroscope Bearing Check1631624.5.2.Calculation of the standard of accuracy for the closure at the breakthrough point1641634.5.3. Possible sources of error in closure1681674.5.4.Final co-ordinates for the hangingwall control network1701694.6.Summary of the findings in this chapter1711704.7.Introduction to Chapter 5173172Chapter 5 Establishment of the Sidewall station Network1741735.1. Introduction1741735.2. The establishment of the Sidewall survey station network1751745.3. The co-ordinates of the Sidewall station network1781775.4. Sidewall Survey station survey method accuracy evaluation1801795.4.1.Description of the observation methodology1811805.4.2.Description of the sidewall station Freestation calculation methodology1871865.5. Sidewall station observations1901895.6.Sidewall station data analysis2192175.7. Closure obtained at the breakthrough point2222205.8.Observations on the sidewall station survey method2232215.9.Introduction to Chapter 6224222Chapter 6 . Three case studies involving sidewall station networks in the mining environment2252236.1. Introduction2252236.2. Rustenburg Platinum mines, Siphumelele 2 shaft2262246.2.1.The establishment of the Sidewall survey station network2282266.2.2.Description of the observation methodology2312296.2.3.Method of evaluating the accuracy of the Sidewall Survey stations2352336.2.4.Sidewall station network results2362346.2.5.Closure obtained at the breakthrough point2372356.2.6.The two-point freestation method2392376.2.7.A Comparison between the two methods2442426.2.8.Conclusion2462446.2.9.Does the sidewall station method meet MHSA standards?2472456.2.10.Is the sidewall station method a safer method of surveying?2472456.2.11.Does the sidewall station method provide a faster method of surveying?2492476.2.12.Issues encountered during the survey study:2492476.2.13.Perceived advantages of the sidewall station method:2502486.2.14.Perceived disadvantages of the sidewall station method:2512496.2.15.Suggestions and recommendations for using the sidewall station method would include:2522506.3. South Deep Mine, 50 Level study2542526.3.1.The use of the Sidewall survey station network2552536.3.2.Methods and Standard procedures employed2572556.3.3.Closures obtained2592576.3.4.Does this method meet the minimum standards of accuracy?2612596.3.5.Is this method a safer method of surveying?2612596.4. Palaborwa Mining Company, Copper mine2622606.4.1.Methods and Standard procedures employed2632616.4.2.Closures obtained2642626.4.3.Does this method meet the minimum standards of accuracy?2672656.4.4.Is this method a safer method of surveying?2682666.4.5.Further advantages or disadvantages of the method?2682666.5. Conclusion268266Chapter 7 . A critical analysis of current international practice: lessons towards developing South African standard mine survey procedures2702687.1. An overview of international wall survey standard procedures2702687.2. Phase 1. Preparation2712697.2.1 Safety considerations2712697.2.2. Equipment used2722707.3. Phase 2. Installation2732717.3.1Survey Station installation2732717.3.2 Positioning of survey stations (wall stations)2732717.3.3 Marking the point2742727.3.4 Protecting the point2742727.4. Phase 3. Observation protocol2752737.4.1. Geometry of observations2752737.4.2. Maximum and minimum angles and distances2762747.4.3. Number of observations2772757.4.Phase 4. Calculation methodology2782767.5.Phase 5. Storage and presentation2792777.5.1. Record keeping2792777.5.2. Pickup instructions2802787.6. Check surveys2802787.6.1.Accuracy2812797.6.2. Methods of check surveying2832817.7.SWOT analysis of current international survey practice using wall station type surveying methods2842827.7.1.Strengths2852837.7.2.Weaknesses2862847.7.3.Opportunities2872857.7.4.Threats2882867.8.Considerations for the development of a standard practice unique to South African mine surveying2892877.9.Conclusion291289Chapter 8 . A proposed guideline for the establishment of a Sidewall Station Survey network2942928.1.Introduction2942928.1.1. Scope of this guideline2962948.2. Change management2972958.3. Proposed guidelines for the establishment and propagation of a sidewall station survey network2982968.4. Phase 1. Preparation2992978.4.1Safety considerations2992978.4.2Planning of the network3023008.4.3Equipment used3043028.4.4Personnel requirements3053038.5. Phase 2. Installation3083068.5.1Survey Station installation3113098.5.2Changing to a sidewall survey station network from a hangingwall network3113098.5.3Changing to hangingwall network from a sidewall survey station network3123108.5.4Positioning of sidewall survey stations3123108.5.5Marking survey stations3133118.5.6Protecting survey stations3143128.6. Phase 3. Observation protocol3143128.6.1Risk factors in observation3153138.6.2Geometry of observations3183168.6.3Maximum and Minimum angles and distances3203188.6.4 Number of observations3233218.6.5Field notes3293278.7Phase 4. Calculation methodology3293278.8. Phase 5. Storage and presentation3323308.9. Phase 6. Check survey3343328.9.1.Check survey baseline3353328.9.2.Accuracy3353338.9.3.Process of check survey adjustment3363348.10.Conclusion338336Chapter 9. Three dimensional mining control using sidewall stations, a solution.3403379.1.The requirements for direction and gradient mark-up.3403379.1.1.Direction lines and gradient control by conventional means.3413389.1.2.Setting-out gradient using the minor dip method.3413389.1.3.An application of the theorem for the intersection of two lines.3423399.2.Site application of the intersecting lines method.3463439.3.Evaluation of setting-out technologies and techniques3513489.3.1.The gradient control method.3523499.3.2.Direction control using marks made on the grade strings.3533509.4.A review of current laser technology.3543519.4.1.String suspended lasers.3543519.4.2.In-line Suspended tunnel lasers.3573549.4.3.Dual-beam laser devices.3583559.4.4.Sleeve laser devices.3593569.4.5.Long range mounted laser systems.3623599.4.6.Applications for totalstation technology.3633609.4.7.A perspective on developing technologies.3653629.5.Interpretation based on the SWOT analysis.3663639.5.1.How can the strengths of the method or technology be used to overcome the identified threats?3663639.5.2.How can the strengths of the method/technology be used to take advantage of the opportunities?3673649.5.3.How can the weaknesses be addressed to take advantage of the opportunities?3683659.5.4.How can the weaknesses be minimized to take overcome the threats identified?3693669.6.Conclusions and recommendations.3703679.6.1.An estimation of the cost of technology as a percentage of development cost.373370Chapter 10. Conclusion and Recommendations37737410.1Introduction.37737410.2Evaluation of the precision of the sidewall survey station network38237910.3Evaluation of the accuracy of the sidewall survey station network38638310.4Conclusion38838510.5Recommendations39238910.5.1National Standard Operating Procedures for Mine Surveying39539210.5.2Change management to introduce the sidewall station method of surveying39639310.5.3The effect of the misalignment of the optical centre and the nodal point of a prism39839510.5.4The calculation of quality control parameters in the establishment and maintenance of underground survey networks39839510.5.5Confidence limit of minimum standards of accuracy and error ellipses39939610.5.6Shaft surveying technique and monitoring of the position of shaft wires using the freestation method of surveying40039710.5.7Measuring and profiling of underground excavations40139810.5.8The effect of elastic rebound and tunnel deformation on the movement of sidewall reference points40139810.5.9Underground location with transponders in sidewall stations40239910.6Conclusion403400BibliographyIIAppendix 1.XIIIXIXAppendix 2.XIIIXXAppendix 3.XIIIXXIAppendix 4.XIIIXXIIIAppendix 5.XIIIXXVAppendix 6.XIIIXXVIAppendix 7.XIIIXXVIIAppendix 8.XIIIXXVIIIPhase 1. PreparationXIIIXXXIPhase 2. InstallationXIIIXXXVIIPhase 3. Observation protocolXIIIXLVPhase 4. Calculation methodologyXIIILPhase 5. Storage and presentationXIIILIPhase 6. Check surveyXIIILIIAppendix 9.XIIILVIAppendix 10.XIIILVIIAppendix 11.XIIILVIIIAppendix 12.XIIILXXVIIIAppendix 13.XIIICVIIAppendix 14.XIIICIXIndexXIIICXIII

List of figures

Figure 1. Variation of rock temperature w.r.t. time and distance66

Figure 2. Hangingwall Traverse diagram94

Figure 3. Triangulation diagram95

Figure 4. A diagram of a Trilateration.96

Figure 5. A Resection observation99

Figure 6. Software freestation method101

Figure 7. The Double "zig-zag" method121

Figure 8. A Typical Mine Tunnel139139

Figure 9. The Project tunnel139139

Figure 10. Vertical Entrances to the Tunnel141141

Figure 11. Plan of project area.142142

Figure 12. Conventional hangingwall surveying terminology156155

Figure 13. Underground setup Figure 14. Tunnel on campus157156

Figure 15. A spad sighted through the telescope Figure 16. Laser pointer on spad161160

Figure 17. Gyrobase in tunnel163162

Figure 18. Idealized Gradeline Layout176175

Figure 19. Sidewall stations in tunnel177176

Figure 20. Sidewall station Figure 21. Station with Large Prism178177

Figure 22. Sidewall station network installation179178

Figure 23. Sidewall station installation and check observation. Graphics by H Grobler180178

Figure 24. Sidewall station observations182180

Figure 25. Re-surveying the control points from the freestation182181

Figure 26. Plan of sidewall station network186185

Figure 27. Idealized Freestation187186

Figure 28. Setup at UJ004190189

Figure 29. UJ004 Setup 1 using two observation rays191190

Figure 30. UJ004 Set-up 2 Observation rays192191

Figure 31. UJ004. Setup 3 using five observation rays193192

Figure 32. UJ005 Setup 1 using two observation rays194193

Figure 33. UJ005 Setup 2 using three observation rays195194

Figure 34. UJ005 Setup 3 using four observation rays196195

Figure 35. . UJ005 Setup 4 using two observation rays197196

Figure 36. UJ012 Setup 1 using two observation rays198197

Figure 37. UJ012 Setup 2 using two observation rays199198

Figure 38. UJ012 Setup 3 using two observation rays200199

Figure 39.. UJ012 Setup 4 using three observation rays201200

Figure 40. UJ014 Setup 1 using two observation rays.202201

Figure 41. UJ014 Setup 2 using three observation rays203202

Figure 42. UJ014 Setup 3 using four observation rays204203

Figure 43. UJ015 Setup 1 using two observation rays205204

Figure 44. UJ015 Set up 2 using three observation rays206205

Figure 45. UJ015 Setup 3 using four observation rays207206

Figure 46. UJ015 Setup 4 using two observation rays208207

Figure 47. UJ015 Setup 5 using two observation rays210208

Figure 48. UJ015 Setup 6 using two observation rays211209

Figure 49. UJ015 Setup 7 using two observation rays211210

Figure 50. UJ015 Setup 8 using two observation rays213211

Figure 51. GH832 Set up 1 using two observation rays214212

Figure 52. GH832 Set up 2 using two observation rays215213

Figure 53. GH832 Setup 3 using four observation rays216214

Figure 54. 11 Level Main Cross Cut227225

Figure 55. Brass Plug and Bayonet attachment230228

Figure 56. Sidewall Station230228

Figure 57. Installation of sidewall stations.232230

Figure 58. Freestation setup from sidewall stations232230

Figure 59. Idealized freestation setup of Sidewall stations in tunnel233231

Figure 60. Two point sidewall station method240238

Figure 61. Installation of plug.258256

Figure 62. Plastic plug and equipment.258256

Figure 63. Installed Prism.258256

Figure 64. Software and instrument setup.258256

Figure 65. Graph of tolerances from Two point setups260258

Figure 66. Three point setup tolerances260258

Figure 67. The mining layout of the copper mine262260

Figure 69. Target with attachment263261

Figure 68. Target installed263261

Figure 70. Check survey origin of the contractor264262

Figure 71. Diagram of the check survey route265263

Figure 72. A high level flow diagram of the survey process. [180]298296

Figure 73. A cause and effect diagram of survey information. [181]303301

Figure 74. Idealized station layout.322320

Figure 75. A graph of the subtended angles at incremental distances from the base stations322320

Figure 76. A diagram of a two point configuration324322

Figure 77. A diagram of a three point configuration325323

Figure 78. A diagram of a four point configuration327325

Figure 79. Diagram of the intersection of lines344341

Figure 80. Tie distances from intersecting lines345342

Figure 81 The installed gradepeg348345

Figure 82 The aligned gradient and direction lines349346

Figure 83 Direction line mark on the gradestring350347

Figure 84 Driftscope device354351

Figure 85. Suspended laser device (Foton Laser [167] )355352

Figure 86. Oblique offsets diagram.361358

Figure 87. Tunnel laser362359

Figure 88. Flowsheet for sidewall stations. [180]XIIIXXIX

Figure 89. Check survey baseline legendXIIILIV

List of tables

Table 1. FGCS Minimum closure standards for Engineering and Construction Control Surveys [35]36

Table 2. ICSM SP1.7. Classification of Horizontal Control Survey [39]39

Table 3. A Comparison of the various limits of error48

Table 4. Decision scale for matrix132132

Table 5 Pair wise comparison matrix of Factors132132

Table 6 Pair wise comparison matrix for Safety133133

Table 7 Pair wise comparison matrix for Accuracy133133

Table 8. Pair wise comparison matrix foor Reliability134134

Table 9 Pair wise comparison matrix for Redundancy135135

Table 10 Pair wise comparison matrix for Refraction influence135135

Table 11 Normalized Matrix135135

Table 12. Specifications of Leica instrument used147147

Table 13. Maximum expected centering error162161

Table 14. Gyro baseline calibration.163162

Table 15.Inter station distances and Total length of closed traverse165164

Table 16. Standard of Accuracy calculation165164

Table 17. Co-ordinate list of Final control points.171170

Table 18. Co-ordinates of the Sidewall stations180179

Table 19. UJ004 Setup 1 using two known points191190

Table 20. UJ004 Setup 2 using three known points192191

Table 21. UJ004. Setup 3 using five known points193192

Table 22. UJ005 Setup Observation 1 using two known points194193

Table 23. UJ005 Setup Observation 2 using three known points195194

Table 24. UJ005 Setup Observation 3 using four known points196195

Table 25. UJ005 Setup Observation 4 using two known points197196

Table 26. UJ012 Setup 1 Observations using two known points198197

Table 27. UJ012 Setup 2 Observation using two known points199198

Table 28. UJ012 Setup 3 Observation using two known points200199

Table 29. UJ012 Setup 4 Observation using three known points201200

Table 30. UJ014 Setup 1 Observation, using two known points202201

Table 31. UJ014 Setup 2 Observation, using three known points203202

Table 32. UJ014 Set up 3 Observation, using four known points204203

Table 33. UJ015 Setup 1 Observation, using two known points205204

Table 34. UJ015 Set up 2 Observation, using three known points206205

Table 35. UJ015 Setup 3 Observation, using four known points207206

Table 36. UJ015 Setup 4 Observation, using two known points208207

Table 37. UJ015 Setup 5 Observation using two known points209208

Table 38. UJ015 Setup 6 Observations using two known points210209

Table 39. UJ015 Setup 7 Observation using two known points211210

Table 40. UJ015 Setup 8 Observation using two known points212211

Table 41. GH832 Set up 1 Observation using two known points214212

Table 42. GH832 Setup 2 Observation using two known points215213

Table 43. GH832 Setup 3 Observation using four known points216214

Table 44. Summary of final Freestation co-ordinates219217

Table 45. Two point freestations220218

Table 46. Final closure results of Breakthrough Freestation.222220

Table 47. Co-ordinates of baseline stations229227

Table 48. Time study of setups235233

Table 49. Comparison of freestation co-ordinate closure237235

Table 50. Calculated Minimum Standard of Accuracy for the survey237235

Table 51. Error vector of freestation closure238236

Table 52. Bearing error comparison239237

Table 53. Freestation co-ordinate comparison241239

Table 54. Closure error242240

Table 55. Calculated Minimum standards of Accuracy242240

Table 56. Distance between resection points245243

Table 57. Minimum standard of accuracy for RS10 to RS12245243

Table 58. A comparison of relative accuracies obtained.245243

Table 59. A compassion of accuracies in co-ordinates246244

Table 60. PMC Closure calculation265263

Table 61 Final closure obtained266264

Table 62 Gyroscope closure267265

Table 63. ISCM standards of accuracy for 1 kilometre.282280

Table 64. MHSA standard of accuracy for 1 kilometre282280

Table 65. Risk analysis for the preparation phase of installing sidewall stations.299297

Table 66. Risk analysis of equipment use during the installation of sidewall stations.306304

Table 67. a Risk analysis for the installation phase of installing sidewall stations.309307

Table 68. Risk analysis for the observation phase of installing sidewall stations.315313

Table 69. Risk analysis for the calculation phase of installing sidewall stations330328

Table 70. Risk analysis of the presentation phase of installing sidewall stations332330

Table 71. Risk analysis of the check survey phase of installing sidewall stations337335

Table 72. Calculated angles of intersection .347344

Table 73. Calculated minor dip to each gradepeg.347344

Table 74 The calculation of vertical angles.348345

Table 75 Calculated tie distances for setting-out.350347

Table 76 Check calculation on bearing and gradient.351348

Table 77 List of tie distances and stake out points.351348

Table 78 A SWOT Analysis of Gradestrings for gradient control352349

Table 79 A SWOT Analysis of Gradestrings for direction control.353350

Table 80 A SWOT Analysis of the Suspended laser.355352

Table 81 A SWOT Analysis of the in-line suspended laser357354

Table 82. A SWOT Analysis of the Dual beam laser.358355

Table 83 A SWOT Analysis of the Sleeve laser.360357

Table 84 A SWOT Analysis of Long range mounted laser362359

Table 85. A SWOT Analysis of the Total station.364361

Table 86 A SWOT interpretation: How can strengths used to overcome threats?366363

Table 87 A SWOT interpretation: How can strengths used to take advantage of opportunities.367364

Table 88 A SWOT interpretation: How the weaknesses be addressed to take advantage of opportunities368365

Table 89 A SWOT interpretation: How the weaknesses are addressed to overcome the identified threats.369366

Table 90 Application matrix of laser technologies.371368

Table 91 cost analysis of laser technology.374371

Table 92 Requirements of a quality intervention.376373

Chapter 1

xii

Introduction

No work shall be done if it cannot be done safely [1] this statement, from the Standard Operating Procedure of a South African mining company, summarizes the main purpose of this research. In South Africa the zero-harm principle is the over-riding philosophy governing every aspect of work performed in the workings of a mine. The previous Minister of Mineral Resources, Minister Shabangu, in an address at the launch of a rescue drill unit for Collieries, stated that the South African mine health and safety performance remains a cause for concern and that the Department of Mineral Resources pursue the ideal of Zero Harm relentlessly [2]. According to the safety statistics for 2013 The major contributors to these accidents were underground mine fires, rockfalls and trackless mobile machinery. [2]. The stated object of the Mine Health and Safety Act is to identify, eliminate and control risks and entrench the rights of workers to refuse to enter a working place or perform work is exposed to risk.

In this context zero-harm is intended to be a commitment to zero fatalities and zero injuries to mine employees, the community and the environment. In the extreme, unforgiving underground environment found in South African mines, in which the conditions make logical thought and the performance of relatively simple tasks difficult, Mine Surveyors need to adapt technology and techniques to perform their allocated duties safely, fast and accurately. Metcalfe remarked in a textbook on Mine Surveying that it is ironical that the most trying branch of underground surveying is that where the greatest accuracy and care are required. [3].According to Livingstone-Blevins the fundamental difference between mine surveying and other branches of surveying is the mitigation of risk, the gravity of the consequences of not getting it right may prove to be fatal [4].

1.1. Mine surveying an overview

Mine surveying has been defined by the International Society of Mine Surveyors as the art of making such field observations and measurements as are necessary to determine the positions, areas or volumes of natural and man-made features on the earth's surface [5]. The Mine Surveyor is responsible for accurately determining the position of all mining excavations relevant to surface infrastructure and boundaries as well as all other adjacent mining excavations. It is the role of the Mine Surveyor to accurately represent these positions on the working plans of a mine. Young remarked that One of the most important phases of mine surveying and probably what requires most care is a survey for openings to connect two given or assumed points. [6].

Mine surveying has been used as the method of referencing the surface features of a mine with underground excavations since the earliest of times. One of the oldest known tunnels is Hezekiah's tunnel or the Siloam tunnel in Jerusalem, completed around 700 BC [7]. This tunnel was 533m long and designed to transport water into Jerusalem. The tunnel remains one of the earliest examples of tunnelling in the world. The tunnel of Eupalinos in Samos, Greece, was excavated in the sixth century BC to serve as an aqueduct. This tunnel was also known to have been excavated from both ends and is considered to have been one of the first to be aligned using geometric principles.

The principles for aligning underground excavations have changed very little during the years while the purpose of alignment has remained the same, namely, to establish a safe connection between excavations with the minimum amount of error in the shortest time possible. Schofield differentiated between surface and underground surveying by stating that the essential problem in underground surveying is that of orientating the underground surveys to the surface surveys, the procedure involved being termed a correlationthus underground control networks must be connected and orientated into the same co-ordinate system as the surface networks [8].

The role of the Mine Surveyor in South Africa is regulated by the requirements of the Mine Health and Safety Act (MHSA). This Act prescribes the minimum standards of accuracy allowable for the accuracy of the position of mine surveying stations as represented on the prescribed underground plans of a mine and prescribes that all excavations must be accurately represented in relation to mining- and mineral rights boundaries, objects on the surface that will require protection as well as any underground excavations that could pose a hazard to workers. Such hazards include areas where there is a possibility of the accumulation of noxious gas, water or mud, should an unplanned holing[footnoteRef:1] be made into such an excavation. Johnson remarked on the importance of accurate and safe alignments of mining excavations by observing that: [1: An event where an excavation breaks into another excavation, in some text this is referred to as a breakthrough.]

Too much stress cannot be laid on the importance of the care to be exercised in running connections, as there is nothing the mining surveyors reputation depends on more directly than his uniform success in this matter. In fact a failure in such a case may involve a large loss to his employer, an error in many cases cannot be remedied, but results in permanent injury to the mine. [9].

This statement still holds true today. The error in the direction or gradient[footnoteRef:2] of a mining excavation can cause large financial losses due to the loss in production caused by re-development and non-adherence to tight production schedules and also the financial and legal applications incurred with the loss of life that could result from unplanned breakthroughs[footnoteRef:3] into hazardous areas. [2: The required inclination of a development end.] [3: An event where a mining excavation breaks into another excavation or area where an accumulation of water or gas may occur.]

The Mine Surveyor has a number of responsibilities that need to be executed on a daily basis to exacting limits of error[footnoteRef:4]. These daily production responsibilities include staking-out of construction lines to control the direction and gradient of development ends[footnoteRef:5] (tunnels). Deviation of these direction and grade lines from the mine design could lead to costly and in some cases permanent, damage to the mine infrastructure, that will require expensive re-development or a change to the original mine design. [4: Refers to the Standards of Accuracy defined by a standard procedure or regulation such as that defined by the MHSA. Also referred to as the minimum standards of accuracy] [5: A tunnel being for the purpose of providing access to the orebody of a mine.]

It is therefore by implication important that the accuracy of the primary survey network falls within the prescribed minimum standards of accuracy and crucial that the survey network is established in accordance with the correct mine design. Livingstone-Blevins argues that any deficiency in the accuracy of a survey network ripples through to other processes with the potential of exposing the mine to risk [4].

Mine surveyors do not have the luxury of being able to close their networks, any alignment and gradient error will only be confirmed when the development end breaks through at the position it was aimed at. In the case of a narrow tabular deposit, the primary survey network is extended underground via transfer of direction in the shaft and then the network is extended on each level of the mine workings. A primary survey network is established on each level and will only be verified once the survey is joined with another primary network on a different level. Normally such verification will only occur if the surveys are joined by the secondary survey that is extended into a raise or winze line. The correlation between the surface and underground workings will most likely only be confirmed in the case of a breakthrough between levels or when an independent check survey[footnoteRef:6] can verify the original survey. [6: A survey made to verify the accuracy of the original survey and the strengthening of the quality of a survey network.]

Cawood remarked on the fundamental changes in the legal framework in which the Mine Surveyor operates. This legal framework defines the manner in which data is collected, processed, presented and reported [10]. The Mine Surveyor must ensure that all surveying work undertaken will satisfy the Mine Health and Safety Act as well as to the required Standards and Procedures determined by his employer. In the current international social- and legal environment, most mining companies have adopted a zero-harm principle in all the activities they engage in. A zero-harm policy requires all employees to adhere to all regulations and corporate requirements in accordance with the MHSA Section 22 and 23(1) these policies normally include the right to leave any working place whenever: (a) circumstances arise that,.appear to that employee to pose a serious danger to the health and safety of that employee as well as the right to refuse to perform dangerous work or entering an area where the possibility of unmitigated risk may be present [11] . According to the MHSA Section 91 Any person, including and employer, who contravenes, or fails to comply with, any; (a)provision of this act(c) .commits and offence and is liable to a fine or imprisonment as may be prescribed... [11]. Safety in the Mine Surveying context must be recognized to have two distinct aspects namely the safety of the surveyor and survey crew with relation to work procedures and equipment and secondly, the safety of mine employees and the public. This second aspect can only be adequately addressed by ensuring the accuracy of the survey network established by the surveyor.

Traditionally surveying stations have been installed in the roof or hangingwall[footnoteRef:7] of mining excavations. In most instances the roof of the excavation would not be more than two metres high, but with the introduction of more efficient methods of tramming rock such as track-bound locomotives and large trucks the dimensions of tunnels have in most instances increased to be in excess of three metres. When the height of the roof of an excavation increases to a point where the roof cannot be reached without the assistance of a ladder or mobile lifting equipment, the task of installing survey control becomes fraught with hazard. In general any work performed at a height greater than 1.5m is defined as working-at-heights. Such work is strictly regulated by company specific on-mine safety standards. These standards have been developed to reduce the incidence of potentially fatal accidents caused by persons falling from heights. [7: The roof of an underground excavation. In some texts this is referred to as the back of the excavation]

This increased focus on safety has arguably had a direct impact on the number of survey stations that a surveyor can install in a production shift. The height factor reduces the visibility of survey control, hampers the identification of survey points and impacts on the accuracy of centring the instrument and target within acceptable limits. A combination of these factors can cause an error to be transferred to the accuracy of subsequent survey stations leading to an unacceptable limit of error in the position of survey stations.

The advancement of technology used for the surveying of underground excavations during the years has rapidly improved the accuracy of survey networks but none more so than in the past 20 years. With the continuous reduction of the size of circuitry coupled with the simultaneous improvement of micro processing power allowing the use of increasingly sophisticated computing software able to perform complicated calculations in the field with minimum effort [12]. Although Hodges and Smith noted that by 1968 an electronic distance measuring devices could be mounted on a normal opto-mechanical theodolite to facilitate distance measuring, total station technology was not fully accepted by the South African mine survey community until the mid 1990s. Modern surveying technology has made the features such as Electronic Distance Measuring, on-board software and electronic recording and downloading standard on most survey instruments.

The increased speed and accuracy of observation offered by such instruments can improve the speed of work of Mine Surveyors thereby assisting in improving their productivity. Any delay in the production process as a result of the installation of survey control can impact negatively on the bonuses paid to production crews. Pretorius and Crous remarked on this fact in their paper, arguing that Where salaries and wages form a high percentage of working cost, every hour of productive work lost must be directly reflected on the cost structure. [13]. Metcalfe made a rather pointed observation regarding this matter underground officials of limited imagination, not realizing the ultimate purpose of a surveyare apt to take a narrow view. [3] As a result any perceived delay in the production process caused by the surveyor will be viewed in a very poor light by the production crews and may very likely the relationship between the surveyor and the production crew in that working end.

In South Africa the perceived lack of suitably qualified Mine Surveyors within the industry has caused an increase in the pressures placed on those surveyors employed on a mine. It has become essential for a surveyor to complete the installation of survey stations in the shortest possible time in order not to impact on the drilling and blasting process while still ensuring that the accuracy of the survey will be within the prescribed minimum standards of accuracy, thereby maintaining the integrity of the survey network. It is becoming increasingly common to find that first-order survey work is done by semi-skilled operators without the necessary in-depth theoretical surveying background. Most of these surveyors do not have a qualification higher than NQF Level 7 or a first degree. In some overseas mining operations the new technology has enabled non-survey personnel such as mining supervisors to be able to take survey and alignment observations with minimal training, reducing the need for a qualified surveyor to visit the working end on a daily basis.

Adapting existing surveying technology and techniques to the underground mining environment could have a significant impact on the improvement of the speed of installing survey stations while at the same time decreasing the associated exposure to working-at-heights by the mine surveying crew.

The South African mining industry has always been perceived to be responsive to research and adapt to new mining technology, but in contrast, the South African Mine Surveying community [14] has been relatively slow to consider alternative surveying techniques to replace [15] the tried and tested methods of surveying that have been used extensively over the past 100 years. Morton commented on this phenomenon by stating that: Resection has never been accepted by the majority of surveyors as a reliable method of obtaining a fix. This is due to the fact that unless the problem of resection is fully understood, serious errors may be introduced and not detected during calculation. [14].

Presently most underground mines in South Africa still make use of technology that would not be unfamiliar to a surveyor from a hundred years ago. Pretorius and Crous argued that Surveyors will agree that they are quite commonly guilty of a form of professional jealousya reluctance to change from a tried and trusted system, This attitude is more often than not short sighted , as the time spent in acquiring the new and better technique might be more than compensated for in the subsequent efficiency resulting from the latter. [13].

1.2. The formulation of the fundamental question

Changes in mining methods and an increased focus on productivity driven by Health and Safety standards and labour efficiency, may lead to increased pressure on some mines to investigate alternatives to the conventional hangingwall method of open traversing to establish survey stations in the underground environment. Gillespie alluded to this fact when he stated that the objections to this method are, the length of time it takes to get the spuds in the roof, and also the difficulty in using them when the roof is high. [16]. The technology is now available to investigate the viability of introducing an alternative surveying technique to the underground environment in order to improve the efficiency and safety of the surveying process.

A number of authors including Pretorius, Crous [13]and Morton [14] have in the past commented on the apparent reluctance among South African Mine Surveyors to accept the accuracy of a survey station obtained by any other method other than hangingwall traversing. The challenge of this research will be to prove that the establishment of a primary survey network of surveying stations in the sidewall of an excavation of between three and five metres in width will be a safe an accurate alternative to a survey network in the roof of an excavation and still comply with the prescribed minimum standards of accuracy. The results of the proposed research will have to answer the following fundamental question: Will the precision of position determination by sidewall survey stations[footnoteRef:8] meet the minimum standards of accuracy as specified by Chapter 17 of the Mine Health and Safety Act no. 29 of 1996 in a narrow tunnel environment typical to South African mines? Should it be determined that the answer to the fundamental question is yes, it must be asked [8: a survey station installed in the sidewall of an excavation in a similar manner as that of a grade-peg , but with the co-ordinates of the survey station accurately surveyed.]

1. how can this be achieved? and more importantly;

2. how will such a method contribute to the zero-harm safety policy of a mine?

1.3. The research outline

The proposed sidewall station survey method will involve the installation of four survey stations drilled and grouted into the sidewall of the excavation at a comfortable height above the floor of the excavation. It is proposed that the position of the survey instrument can be determined by observing angles and distances to four known points. Once the position of the instrument has been determined, the survey will be carried forward towards the advancing face of the excavation or any other position that is required. The viability and accuracy of this alternative survey method has not been tested in mines in South Africa.

It is proposed that survey stations be installed in the sidewall of an excavation and tested to determine the position of the instrument to an acceptable limit of error. It will be necessary to evaluate the impact of the geometry of the placement of survey stations in relation to the unknown point on the accuracy of survey stations installed in this manner. The findings of the test phase will be evaluated in a narrow tunnel environment at a deep level South African mine to determine if the results obtained will meet the current minimum standards of accuracy.

1.4. Overall objectives

The objective of the proposed research is to determine whether the accuracy of a network obtained from observations made from sidewall survey stations is within the minimum standards of accuracy defined by the Mine Health and Safety Act of 1996 (Act 29) for a Class A primary survey network control. In order to investigate the accuracy of the proposed survey method it will be necessary to establish a survey network in a controlled environment where there will be minimal interference with the installation of survey stations and the observations process. The specific objectives of the research were:

1. To establish a survey control network using the accepted method of hangingwall traversing to within the minimum standards of accuracy prescribed for a Class A primary survey network.

2. To establish on the same site, a survey control network using the sidewall surveying method using a closed traverse method, closing the survey on the point of origin.

3. To evaluate the accuracy of closure obtained by the sidewall survey stations with the prescribed minimum standards of accuracy as defined by the MHSA.

4. To evaluate the accuracy obtained between the conventional hangingwall survey method and the proposed sidewall survey station method.

5. To test the accuracy, safety and efficiency of the proposed survey method in the narrow tunnel environment of a working mine.

6. Based on the outcomes of the above points, to determine if the alternative method of surveying is a safe and accurate alternative to standard South African mine survey methods

7. To evaluate the associated risks involved in the survey techniques and

8. Outline suggested practices to ensure the safety and accuracy of the alternative survey method for practical implementation in South African mines.

1.5. Methodology

A service tunnel located under the Doornfontein campus of the University of Johannesburg provided the test site for this research. The tunnel with average dimensions of three metres wide by three metres high, is 160m in length and terminates in a 180m long cross tunnel. The tunnel provided similar dimensions to the narrow tunnel environment found in most South African mines. The tunnel does not carry the normal risks associated with underground mining tunnels as the area is free from ventilation and rock pressure issues and therefore provided a safe, controlled environment with almost no traffic to disturb any work taking place.

The experimental site was surveyed in the traditional hangingwall traverse method and the survey closed on the point of origin and the co-ordinates balanced. Such a closed traverse is not standard practice in the underground environment, but the accuracy of the conventional survey had to be verified to be within the acceptable minimum standards of accuracy for a primary survey network.

The same route was then re-surveyed using the sidewall station method of surveying, using a minimum of four sidewall stations for each setup. Both surveys were closed at the same point of closure in order to determine the error in closure for the survey. The accuracy of this survey method was compared to the acceptable minimum standards of accuracy for a primary survey network. A comparison was drawn between the positions obtained by the two different survey methods. Data was collected by making observations using a single second total station using only the standard on-board software of the instrument. In order to collect data that would take the following parameters into consideration:

The optimal distance between target and instrument setup position;

the effect of incorrect target alignment and placement of targets with specific reference to the geometry of the setup;

the effect of incorrect target identification including the effect of observations made by infrared to target as compared with measuring distances using a reflector-less method of observation; and

the optimal method of sidewall peg installation including the method of:

Positioning the survey stations for optimal geometrical alignment;

permanently fixing the point in the sidewall by grouting or friction; and

Determining the effect of contamination by dirt and oxidization of the sidewall station plugs on the accuracy of observations.

The final orientation of the survey network case study was checked for angular closure using observations from a gyroscope to verify the final bearing closure of the proposed survey method, compared to the original survey. A full analysis of the closures obtained was made in order to determine whether the new proposed method of surveying complied with the minimum accuracy requirements for a primary survey network as currently required by the Mine Health and Safety Act.

1.6. An overview of the literature search and further chapters

The following chapters will attempt to review relevant current knowledge in the field of Mine surveying and related industries with reference to techniques, standards, procedures and legislation that impact on current mine surveying practice.

Chapter 2 will be investigate current Mine Survey and other Legislation, Industry Standards and Codes of Practice, both nationally and internationally. As part of the investigation process, recent health and safety incidents in the international mining environment where mine surveying played a contributing role will be discussed. As part of this industry standards review, the effect of external variables such as illumination, refraction, production pressure and the regulation of working-at-heights on the safety, accuracy and productivity of mine surveys will be considered.

Chapter 3 will review the history of developments in survey technology and briefly analyses the range of surveying technology currently available. It is argued that, given the availability of modern survey equipment, the speed and accuracy of surveying has been greatly improved, but at the same time, relatively few alternative methods of surveying have been developed to replace the tried and tested methods of mine surveying that have in most cases been in use since 1900. The conventional methods of obtaining the spatial position of survey points will be discussed and modern applications of technology used in large tunnelling projects and international mining operations are investigated. A number of recent large projects will be discussed with specific reference to the method of surveying used at each of these projects.

Chapter 4 details the setup of the experimental survey network using a standard hangingwall survey as the control. The proposed method of using sidewall survey stations as the basis for establishing a primary underground survey control network will be tested in a controlled environment to evaluate the accuracy of the method. The chapter outlines the controls put in place during the research to attempt to ensure the quality of the survey network and the new proposed method of surveying to be applied will be discussed in detail.

In Chapter 5, the results of the observations made under the controlled conditions of the test facility and the subsequent analysis of this data will be used to evaluate the accuracy of the sidewall survey station method compared to the traditional control survey, prior to being tested in a working narrow tunnel environment. The process of establishing a sidewall survey station network from existing hangingwall control, the extension of such a network and the results of the analysis of the geometry of sidewall stations obtained will be discussed. The minimum standard of accuracy obtained through the two methods of surveying will be compared against the requirements of a Class A survey as described by the MHSA.

Chapter 6 evaluates the implementation of the proposed sidewall survey station method of surveying under the real production conditions of a mine. The full scale in a working mine is tested at a deep level South African mine. The method of surveying and any adjustments to the proposed method of surveying will be discussed and analysed in this chapter. The closures obtained by the new method be compared against the minimum standards of accuracy of a Class A survey as defined by the MHSA.

Chapter 7 evaluates the current Standard Operating Procedures and Guidelines followed in similar methods of surveying nationally and internationally, with the intention of compiling a proposed guideline relevant to the South African mining context.

Chapter 8 outlines the new knowledge obtained from this research and sets out a guideline to describe the method of establishing and extension of a sidewall survey station network. Factors that could have an influence on the accuracy and safety of the proposed survey method will be discussed. The suggested guidelines include the geometry of survey observations, the placement of survey reference points and the minimum number of reference points to be used to ensure that the minimum standards of accuracy will be obtained during a survey. It is recommended that this chapter be read in conjunction with Appendix 7 which is intended to serve as a proposed outline for a Standard Operating Procedure for sidewall station survey networks on a South African mine.

Chapter 9 evaluates solutions for marking up the direction and gradient control using sidewall stations. The combination of gradelines and lasers as well as alternative technologies is discussed.

The final conclusion and recommendations drawn from the experimental survey and the actual narrow tunnel deep mine test are made in Chapter 10. This chapter attempts to prove that the sidewall survey station method of surveying will achieve comparable results meeting the prescribed minimum standards of accuracy when compared with the accuracies achieved through traditional hangingwall surveying. The final conclusion attempts to answer the question outlined at the start of the thesis: Will the precision of position determination by sidewall survey stations meet the minimum standards of accuracy as specified by Chapter 17 of the Mine Health and Safety Act no. 29 of 1996 in a narrow tunnel environment typical to South African mines?

Chapter 2 Regulations, Standards and Codes of Practice

The role of the Mine Surveyor has not changed significantly from medieval times when Agricola described the principal duties of the Mine Surveyor to determine the direction of mine workings and to ensure that no encroachment upon neighbouring properties has taken place. In this chapter it will be attempted to analyse current national and international legislation and industry standards defining the limits of accuracy and working standards employed in mining and tunnelling projects. The impact of various Safety and Health requirements on the working procedures of a Mine Surveyor will be investigated by comparing a number of corporate Standards and Procedures related to working-at-heights in the mining environment. As part of the investigation the impact of external influences such as refraction and strong ventilation on the accuracy of a survey will be discussed.

2.1. The South African Legislative Environment

The Mine Surveyor in South Africa operates in an environment strictly regulated by legislation and corporate Standards and Procedures. The preamble of the South African Mine Health and Safety Act, No. 29 OF 1996 declares that the object of the Act is:

To provide for protection of the health and safety of employees and other persons at mines and, for that purpose -

to promote a culture of health and safety;

to provide for the enforcement of health and safety measures;

to regulate employers' and employees' duties to identify hazards and eliminate, control and minimise the risk to health and safety;

to entrench the right to refuse to work in dangerous conditions; [17]

The MHSA requires that:

2. (1) The owner of every mine that is being worked must

(a) ensure, as far as reasonably practicable, that the mine is designed, constructed and equipped

(i) to provide conditions for safe operation and a healthy working environment; and

(b) ensure, as far as reasonably practicable, that the mine is commissioned, operated, in such a way that employees can perform their work without endangering the health and safety, of themselves or of any other person; [17]

According the Act Chapter 2 (9)(2); a code of practice must be prepared and implemented for any practice affecting the health or safety of an employee or other person directly affected by the activities of a mine. Such a code of practice must comply with the guidelines issued by the Chief Inspector. It is required Chapter 2 (11)(1))(a) and (b) to identify, assess and record any risks to health and safety to which employees may be exposed to and design safe systems of work necessary to eliminate, control or minimize the recorded risks.

The MHSA Chapter 2 (22) stipulates that It is an offence to fail to comply with a duty under this Act and it is the employees duty to take reasonable care to protect the health and safety of themselves and other persons who may be affected by any act or omission of that employee; [17]. As stated in the objectives of the Act, Chapter 2 (23)(1) as well as (30)(1)(b)

The employee has the right to leave any working place whenever

(a) circumstances arise at that working place which, with reasonable justification, appear to that employee to pose a serious danger to the health or safety of that employee; [17]

It is deemed an offence by this Act to discriminate against an employee who has asserted any right granted by this Act [17].

The MHSA describe the Inspectors power in Chapter 5 in the following manner in Chapter 5 (54) (1):

If an inspector believes that any occurrence, practice or condition at a mine endangers or may endanger the health or safety of any person at the mine, the inspector may give any instruction necessary to protect the health or safety of persons at the mine, including but not limited to an instruction that -

(a) operations at the mine or a part of the mine be halted;

(b) the performance of any act or practice at the mine or a part of the mine be suspended or halted, and may place conditions on the performance of that act or practice; [17]

In recent times the issuing of a Section 54 by the Inspector of mines have become standard procedure in any event where a serious injury or fatality has occurred. The issuing of a Section 54 implies that all production activities on the mine must be stopped until the Inspector has been satisfied that any conditions in contravention of the Act have been rectified. The stop in production can lead to significant financial losses for a mining company. According to the Act, it is an offence to fail to comply with an Inspector's instruction. It is defined in the MHSA Chapter 7 (91)(1) that a person commits an offence who contravenes or fails to comply to the provisions and regulations of this Act and may be sentenced to a fine or imprisonment according the jurisdiction of the Magistrates court. [17]

Within the context of the MHSA Act it is therefore obvious that the primary focus of the mining industry is safety above all else. Mine Surveyors therefore do not only have amoral obligation to ensure the accuracy of their work but also a legal responsibility to ensure the safety of mine employees as well as those of the community. [8].

The Mine Surveyor have in recent times been forced to adapt to a role that sees them ensuring that the core business drivers of their employers are met, while at the same time ensuring that all work is performed in compliance with all the relevant Safety and Health and company Standards and Procedures. [18]

As a result of these core business drivers, the most important of which is safety, it will be necessary to determine how this alternative method of surveying will conform to the requirements of accuracy stipulated by the Mine Health and Safety Act as well as corporate Standards and Procedures. It is important to evaluate the various defined limits of accuracy found internationally in order to draw a suitable conclusion regarding the application of these limits to the proposed method of surveying. The accurate positioning of mine workings in relation to mine boundaries and features that may require protection from undermining or from accidental breakthrough into areas that may contain water, mud or gas that could endanger the lives of mine employees is of the utmost importance. In addition to these points, the accurate representation of all mine workings in relation to surface features is important for the construction of rescue plans. It has been observed by Young that Frequently mine maps must be produced in court as evidence. In all cases such maps should be so complete and so carefully prepared that no questions can arise in regard to the accuracy of the work of the engineer. [6]. It is crucial to understand that the accuracy and consistency of the survey method that provides the control for the representation of such workings on plan meet current legal requirements and evaluate any alternatives that may prove more suitable than these regulations.

2.1.1. Major contributors to injuries and Fatalities in the South African mining industry

In the South African Mining Industry, the main contributors to fatalaties and injuries have been identified as Falls-of-ground, Machinery, Transportation and Mining activities [19]. Falling from heights have also been identified as a major contributor to both fatalities and injuries [20]. According to the MHSI newsletter, in the period April to June 2013 37% of the 19 reported fatalaties were as a result of Falls-of-ground and 16% due to transportation and mining [21]. Mine surveyors in the execution of their duties are exposed to these hazards on a daily basis as the survey stations are installed in the hangingwall of the excavation and while observing, the surveyor is directly positioned in the way of conveyances and transportation equipment. It was noted by Metcalfe that the minds of the mine surveyor and the crew during surveying operations should be fully concentrated on the work in hand and free from anxiety regarding their safety [22].

2.2. Recent Mine safety incidents related to mine surveying

The importance of accuracy in Mine surveying has been highlighted in the recent past by mining incidents where the accuracy of mine plans has had a direct impact on the health and safety of mine workers and the communities living around the mining area. It is important to understand how these incidents relate to the accuracy of mine survey networks as in these cases accuracy and safety is inter-related.

2.2.1. The Gretley Coal Mine Disaster

The disaster at Gretley coal mine in Australia highlighted the need for accurate mining plans. According to a report based on the findings of the investigation into the matter when Disaster struck the Gretley Colliery near Newcastle (New South Wales. Australia) on 14 November 1996. Miners inadvertently broke through into the flooded workings of an old abandoned mine, and four miners died in the inrush of water. [23] It was found during the investigation that The Mine Surveyor at the time assumed that the plans provided by the department were accurate and the manager, relying on his surveyor, made the same assumption. [23] The incorrect plans were described as a classic example of latent error, as the judge in an earlier inquiry noted, the plans sat like a loaded gun in the archives, waiting to be fired. The investigation found that the inrush from old workings was a well-known hazard with the potential to cause multiple fatalities, [23]. In South Africa the accuracy of surveying and the plans generated from this surveying information is aimed at preventing such occurrences. In the case of the Gretley coal mine disaster the company was fined $730 000 [23]. It is interesting to note that subsequent to these findings the MHSA was amended to include a provision stipulating that the employer must take reasonable measures to ensure that a competent person determines the accuracy of any plan not prepared by him or her where such a plan may create a risk of endangering the health and safety of any persons. [11]

2.2.2. Beaconsfield Mine 25 April to 9 May 2006

During the Beaconsfield Mine tragedy on ANZAC Day 2006 the role of the Mine Surveyor was one of monitoring the progress of the rescue effort and guiding the mining operations towards the position of the trapped miners. The report describes how Probe holes were drilled with one breaking through that the two miners could touch. A few hours later in the early hours of the 9th of May, 2006 the two miners were freed and the rescue mission successfully completed. [24]. This sterile description of the events leading up to a drill hole 15.5metres being aligned, drilled and holed exactly between the heads of the two trapped miners lying ion their sides in a small cavity does not do justice to the skill of the surveyor who had to employ every skill of his profession [25]. The 54mm diameter drill hole would establish a link between the trapped miners and the rescue team through which food, water and medication could be provided to the miners. The margin of error normally afforded to align a 4.5 metre by 4.5 metre excavation would not be sufficient to ensure a successful holing. The surveyor, Simon Arthur, had to align the drill rig with a small spot 15.5 metres into solid rock between the two men. Piscioneri, following Simon Arthurs calculations, had drilledprecisely between the heads of Todd Russel and Brant Webb. The whirling drilling head, still spewing water, had rained all over them. [25] This dramatic account of the rescue attempt underlines the often forgotten role of the accuracy required of work routinely performed by mine surveyors under extremely difficult circumstances. The accuracy of the survey network and survey techniques used by Mr. Arthur could be said to be the main contributing factor to the successful of two miners trapped for 14 days in a cavity of rock barely large enough to accommodate the two miners.

2.2.3. The Chilean Mine Rescue

The recent event (October 2010) in which 33 Chilean miners were trapped underground, further emphasises the importance of up-to-date and accurate mine plans produced by the Mine Surveyor, as well as the accuracy of the survey techniques used to construct these plans. According to news reports at the time of the discovery of the miners Rescuers had tried seven times before to reach the shelter, most recently drilling 2,300 feet (700 meters) and missing the target on Thursday. They blamed the error on the companys maps of the mine. [26] When eventually located The miners sent up notes attached to probes drilling into the area of a refuge located 2,297 feet -- almost one-half mile -- underground. [27] According to Livingstone-Blevins more than 14 000 measurements were made on the 10000metres of boreholes drilled during the rescue operation [4]. The drill holes served as the only contact to the outside world for the trapped miners, serving as the only access to food, water and communications. The rescue was eventually successful but it could be speculated that updated and accurate mine plans would probably have enabled the rescuers to locate and contact the trapped miners faster than was the case. The accurate location of the refuge chambers would possibly have saved some of the tremendous drilling costs that were incurred during the rescue.

2.3. An Overview of relevant standards of accuracy.

The extreme environment in which the Mine Surveyor must perform his duties is strictly regulated by the accuracy requirements imposed by the state and the mining companies. As has been illustrated by the previous section, the lives of mine workers depend directly on the accuracy of the survey network that controls the workings of the mine in which they work. Bannister stated that understanding the minimum standards of accuracy that limit the accuracy of the measurement techniques is but one step to ensuring specifications are achieved [28]. In order to understand the numerous standards of accuracy employed in the mining and tunnelling environment a summary of the most relevant Acts, Regulations and standard Procedures will be discussed in the next session.

2.3.1. The Mine Health and Safety Act; 1996 (Act 29 of 1996)

In the South African context all mine surveying work is regulated by the Mine Health and Safety Act. Primarily the Mine Health and Safety Act, Chapter 2 (22) requires that:

every employee at the mine, while at the mine must: (f) comply with the prescribed health and safety measures. It is an offence to fail to do anything required by this act 91(1) Any person, including and employer, who contravenes, or fails to comply with, any; (a)provision of this act(c) .commits and offence and is liable to a fine or imprisonment as may be prescribed. [11]

The first time that the minimum standards of accuracy for Mine surveying were described in South Africa was in a Volksraad Besluit dated the 25th of July 1894, Article 997, titled Instructies voor Mijnopmeters in de Zuid Afrikaanse Republiek regulating mine surveying activities in the Transvaal province of South Africa. It stated that the Mine Surveyor was to be held responsible for the accuracy of all the work performed by him and would be held responsible for any damage that resulted from any inaccuracies. According to these regulations a surveyor needed to perform all work to the following allowable error in the horizontal plane of 1/500 and a lateral deviation of 1/750 from the measured length. In the case of special surveys that required the determination of the position of shafts and connecting drives in the case of closures, the allowable error would be half of the defined allowable error [29].

The most recent update of the Mine Health and Safety Act, 1996 (Act 29 of 1996) Chapter 14 (5) requires that the employer must take all reasonable measures to ensure the safety of all persons that may be endangered by mining operations [17]. An unplanned breakthrough caused by inaccurate surveying may result in loss of life caused by the fall of ground[footnoteRef:9], injury by explosives or the inrush of water or gas into a working end. The consequences of an unplanned breakthrough as the result of inaccurate survey plans, was demonstrated in the Gretley Coal Mine disaster in Australia. The investigation found that theInrush from old workings was a well-known hazard with the potential to cause multiple fatalities, [23] [9: A collapse of rock from the roof or sidewall of an excavation, normally gravity induced]

The MHSA regulations make clear provision for the limits of accuracy to be expected from any survey. The minimum standards of accuracy prescribed by the Mine Health and Safety Act are as follows:

17(14)(b)the minimum standard of accuracy and class of survey for the fixing of survey stations on both horizontal and vertical planes are in accordance with the following formula:

( 1 )

Where s is the distance in metres between the known and the unknown survey station; provided that in the case of a traverse, after a check survey has been completed, the error in direction of a line between any two consecutive survey stations must not exceed 2 (two) minutes of arc, provided that the horizontal and vertical displacement between the measured position and final position of a survey station does not exceed 0,1 (zero comma one) metres; [17].

The MHSA makes a clear distinction between three classes of survey accuracy required under defined circumstances, namely:

17(14)(b)(i)the allowable error for a Primary Survey (Class A) is not greater than A metres. Primary Survey means any survey carried out for the purpose of fixing shaft positions, shaft stations, underground connections, upgrading of secondary surveys to primary surveys and establishing primary surface survey control; [17]

The abovementioned minimum standards of accuracy will be used in the proposed research work as the primary focus will be the establishment of a primary survey network. As can be seen from the error for secondary and tertiary surveys the limit of error remains a function of the limit of error determined for the primary survey network. Chrzanowski defines three orders of survey networks as control networks consist of first order loops which serve as basic control and are run in permanent mine workings, second order traverses run into headings and development areas, and third order stations used for detailed mapping of excavated areas and daily checks of mining progress in stopes and headings [30].

According to the MHSA the second and third order of accuracy for survey networks are defined as follows:

17(14)(b)(ii) the allowable error for a Secondary Survey (Class B) is not greater than 1,5A metres. Secondary Survey means any survey carried out for the purpose of fixing main or access development, mine boundaries and establishing secondary surface survey control; [17].

( 2 )

It can be argued that the accuracy of a survey network on an underground level of a mine can be defined as a secondary survey and therefore be classified as a Class B network with lesser accuracy. The final category of survey network is a tertiary survey defined as survey networks that are extended into the production areas of a mine for measuring purposes and is defined as follows:

17(14)(b)(iii) the allowable error for a Tertiary Survey (Class C) is not greater than 3A metres. Tertiary Survey includes survey stations established from secondary survey stations for localized survey purposes; [17].

( 3 )

It is generally accepted in the South African mine survey industry that a rule of thumb of 20mm should apply to all surveys. In an e-mail communication with Bals, he argues that this rule of thumb is an adaptation of the Class A survey standard using a 60 metre steel tape: 0.015 + (60 / 30000) gives 0.017m or 20mm for easy implementation. [31]. The standards of accuracy are tabulated here to indicate the distance at which the rule of thumb of 20mm applies. It is indicated that the minimum accuracy for a Class A survey is limited to 15mm and a Class B survey as 22mm, which would confirm the rule of thumb of 20mm used in common practice. A tabulation of distances to compare the various classes of accuracy is illustrated in Table 3. A Comparison of the various limits of errorTable 3. A Comparison of the various limits of error

The Mine Health and Safety Act, Chapter 17 prescribes the distances from which any mining may take place from any feature that needs to be protected from mining activities in the following manner: The employer must ensure that

17.6.1no mining operations are carried out under or within a horizontal distance of 100 (one hundred) metres from buildings, roads, railways, reserves, mine boundaries, any structure whatsoever or any surface, which it may be necessary to protect,.. [17]

The regulation requires the employer to ensure that all reasonable measures be taken that no boundary pillars[footnoteRef:10] are mined without the permission of adjacent employers and the inspector of mines [17]. [10: A continuous pillars left in situ on the inside of every mine boundary, the width of which, measured horizontally and at right angles to the boundary line, must not be less than 15(fifteen) metres for underground coal mines and for all other mines a pillar of 9 (nine) metres. [1]]

In the case of a survey 100metres in length the following standards of accuracy are defined. Using Equation 1, a Class A survey will require a closure within 0.0183m. From Equation 2 a class B survey for the same distance would be 0.0275m and for a Class C survey a closure of 0.055metres. [32]

The MHSA makes reference to the original Land Survey Act when defining the limits of allowable error. The minimum standards of accuracy described in the Mine Health and Safety Act makes provision for the conventional traverse surveying method only. In order to better understand the minimum standards of accuracy used for the fixing of co-ordinates of a point by alternative survey methods such as intersection, the Land Survey Act needs to be investigated.

2.3.2 The Land Survey Act, 1997 (Act No 8. of 1997)

The minimum standards of accuracy described in the Mine Health and Safety Act, 1996 (Act 29 of 1996) were derived from the Land Survey Act, described below. This Act describes the accuracy of survey points established by traversing, intersection and resections.

(1)A surveyor shall determine the positions of all stations and beacons within the limits of accuracy prescribed in regulation 5 and shall check every part of his or her survey. [33]

The Land Survey Act describes the geometry of observations that would be acceptable for the location of survey points.

(a) when its position is determined by intersection or trilateration, the angle at the vertex of any triangle used in such determination shall not be less than 30 degrees nor greater than 150 degrees;

The following section of the Act defines the accepted geometry for this type of surveying and will be considered during the research.

(b) when its position is determined by resection, at least four favourably situated known points shall be used, and sufficient observations shall be made to ensure the required accuracy of determination of its position: Provided that at least one arc shall be observed;

(c) when its position is determined by a single triangle only, observations shall be made at all three points and on at least two different parts of the circle;

The limits of allowable error When the position of a point is determined by polars, triangulation, trilateration, derived from the final co- ordinates of the point fixed shall be of the order for triangulation, resections and other forms of fixing the position of a point is defined by the following formula:

( 4 )

Using this equation for a triangulation over a distance of 100 metres 0.0185metres is calculated. For a Class B survey the following equation is used:

( 5 )

Using this equation for a triangulation over a distance of 100 metres 0.0277metres is calculated. For a Class C survey the following equation is used:

( 6 )

Using this equation for a distance of 100 metres 0.0554metres is calculated. [32]. It should be investigated if the formula for calculating a standard of errors for intersections should be introduced to the MHSA. According to the Survey Manual of the Durban Corporation the limits of error for a traverse can be determined by the formula,

( 7 )

Using this equation for a traverse over a distance of 100 metres 0.0142metres is calculated. For a Class B survey the following equation is used:

( 8 )

Using this equation for a traverse over a distance of 100 metres 0.0142metres is calculated. For a Class C survey the following equation is used:

( 9 )

Using this equation for a traverse over a distance of 100 metres 0.0425metres is calculated [32]. If the formula is used to create a table with distances, it can be seen that for distances from 1 to 10 metres the accepted limit of error will be 0.010mm, increasing to 0.012m for distances up to 50m [34], which is a greater accuracy requirement than that of the MHSA for the same distances.

2.3.3 Federal Geodetic Control subcommittee (FGCS), Part 4, USA

The American Federal Geodetic Sub Committee was formed (1) to provide a uniform set of standards specifying minimum acceptable accuracies of control surveys for various purposes, and (2) to establish specifications for instrumentation, field procedures and misclosure checks to ensure that the intended level of accuracy is achieved. [35] . These standards from 1998, were largely based on the existing U.S. Army Corps of Engineers engineering surveying standards. The standards used for aligning tunnels are normally done to 1 part in 10 000 to 20 000 but for extensive projects may increase to 1 part in 50 000 up to 1 part in 100 000 [36]. The committee states that these standards are independent of the method of survey and based on a 95 percent confidence limit According to Wolf and Ghilani triangulation, trilateration and traverse surveys are included in the 1984 horizontal control standards and specifications, and differential leveling is covered in the vertical control section [36]

Table 1. FGCS Minimum closure standards for Engineering and Construction Control Surveys [35]

Traditional surveys Order and Class

Relative accuracy between points

Relative accuracy required between benchmarks (Vertical)

First order

1 part in 100 000

0.5mm*k

Second Order Class I

1 part in 50 000

0.7mm*k

Second Order Class II

1 part in 20 000

1.0mm*k

Third Order Class I

1 part in 10 000

1.3mm*k

Third Order Class II

1 part in 5 000

2.0mm*k

Construction

1 part in 2 500

*k is the distance between benchmarks in kilometers

If these values are converted to be comparable to the MHSA and Land Survey Act allowable errors, for a comparable distance of 100 metres, a third order Class 1 relative accuracy of 1:10 000 correlates the closest to the MHSA Class A standard of accuracy, with a distance of 0.010metres and 0.020metres for a Third Order Class II relative accuracy of 1:5 000 comparing with the Class B survey defined by the MHSA. [32] .

2.3.4. Positional accuracies for primary control systems (ISO4463)

The ISO4463 standard lists that the permissible deviations of distances and angles obtained when measuring positions of primary points, and those calculated from the adjusted coordinates of these points shall not exceed [37] According to Kavanagh, the formula used to calculate the standard of accuracy is as follows:

( 10 )

( 11 )

where:

L is the distance in metres between the primary stations in the case of angles L is the shorter side of the angle

Using these equations to compare the allowable error per distance to that of the MHSA requirements it is found that the allowable error is calculated as 0.0075metres over 100metres, or a ratio of 1:13 333. [32]. These limits of accuracies appear to be for primary high accuracy surveys, normally not found in the underground environment and will not be considered in the research.

2.3.5. Intergovernmental Committee on Surveying and Mapping (ICSM SP1.7)

The Australian committee that implemented the standards and practices defined in version 1.7 of this document defines technical standards and specifications for surveys undertaken at a state or Commonwealth level. and further defines the term of Positional Uncertainty is the uncertainty of the co-ordinates or height of a point, in metres at the 95% confidence limit, with respect to the defined reference frame.. The class of survey network is defined as follows: Class is a function of the precision of a survey network, reflecting the precision of observations as well as suitability of network design, survey methods, instruments and reduction techniques used in that survey. [38]. This code seems to be currently used in most parts of Australia. The standard describes The allocation of CLASS to a survey on the basis of the results of a successful minimally constrained least squares adjustment may generally be achieved by assessing whether the semi-major axis of each relative standard error ellipse or ellipsoid (i.e. one sigma), is less than or" equal to the length of the maximum allowable semi-major axis (r) using the following formula:

r = c ( d + 0.2 ) ( 12 )

Where:

r = length of maximum allowable semi-major axis in mm.

c = an empirically derived factor represented by historically accepted precision for a particular standard of survey.

d = distance to any station in km.

The values of c assigned to various classes of survey are shown in Table 2Table 2.

Table 2. ICSM SP1.7. Classification of Horizontal Control Survey [39]

Class (one sigma)

C value

Typical Application

3A

1

Special high Precision

2A

3

High Precision National Geodetic Surveys

A

7.5

National and State geodetic surveys

B

15

Densification of geodetic surveys

C

30

Survey co-ordination surveys

D

50

Lower class surveys

E

100

Lower class projects

Using Equation r = c ( d + 0.2 ) ( 12r = c ( d + 0.2 ) ( 12 ) for a comparative distance of 100metes the length of allowable semi-major axis is calculated as 0.015metres if the Class D category or lower class surveys are used. This method of defining the semi-major axis of the error ellipse is easy to calculate and should provide a basis for a practical alternative method of defining the standards of accuracy for the current MHSA.

2.3.6. Canadian Survey Standards, General Instructions for Surveys, e-Edition, Appendix E4 Accuracy standard for legal surveys

The Canadian survey standards take a very practical approach to the limits of allowable error and recognize that a single formula cannot serve the purposes of very short surveys, such as those found in an underground survey as well as very long surveys: For a very long survey traverse, the allowable error may be misleading and, in some cases, may conceal a blunder. For a 100 m measurement it can be difficult to meet a 1: 5000 error of closure specification. [40] The error ellipse for the standards was determined using this argument Using normal legal survey instrumentation and methods, 2.0 cm was chosen as an upper limit for an allowable error for a distance of 10 m, and 10.0 cm was chosen as a limit for a distance of 1000 m. [40]. The limit of allowable error can be calculated using the following formula:

r = 8(d+ 0.25)( 13 )

Using this equation for a comparative distance of 100metes the length of allowable semi-major axis is calculated as 0.028metres.

2.3.7. The Institute of Mine Surveyors of South Africa: Guidelines for standard Mine Surveying practice

The technical procedures and guidelines for mine surveying published by the Institu