The Influence of Angle and Aspect on the Established Vegetative Cover on the Slopes of Rehabilitated Discard Dumps in

By

Steven Douglas BLOY

Mini-dissertation submitted in partial fulfilment of the Requirements for the degree of

MASTER OF SCIENCE

In

ENVIRONMENTAL MANAGEMENT

in the Faculty of Science

at the

RAND UNIVERSITY

Supervisor: Prof. J.T. Harmse

September 2004

ACKNOWLEDGEMENTS

I wish to sincerely thank the following people and institutions that have afforded me many opportunities, resources and guidance in the completion of this study and degree as a whole:

• Firstly, I wish to thank my parents for the great sacrifices they have made for me throughout my life. Without your love, patience, faith and guidance I would be lost. Thank you. • Ingwe Collieries Ltd. and its management for the financial support and the provision of the various resources required to complete such a demanding degree. • My friends at Ingwe Mine Closure Operations for their knowledge, guidance and support – keep up the good work. • Jaap Viljoen, Group Environmental Manager of Ingwe, for his trust and belief in me, as well as his guidance and support. • Jaco Kleynhans, Gerhard Jansen van Vuuren and Vik Cogho, friends and Environmental Managers at various Ingwe mines, whose knowledge, generosity, insight and honesty are a constant source of both inspiration and entertainment. • Prof. J.T. Harmse, my supervisor, firstly for his patience and also for his valued time and effort in the review of this study. • RAU and especially the Department of Geography and Environmental Management for the opportunity afforded to me to undertake my postgraduate studies at your fine academic institution. • Richard Garner, Anglo Coal Environmental Services, for his assistance in the gathering of my data and the synthesis thereof. • My brother Bryan, as well as my very good friends who have always been there for me, and through whose mistakes we all learn. • Last, but by no means least, my girlfriend, companion and friend, Lisa van der Walt. Thank you for the best 2 years of my life, as well as all the constant love, support and encouragement you have heaped upon me.

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LIST OF CONTENTS Page ACKNOWLEDGEMENTS ii

ABSTRACT x

1. INTRODUCTION 1 1.1 Background information 4 1.2 Aim of the study 4 1.3 Importance of the study 5

2. REVIEW OF SUCCESSFUL REHABILITATION PROJECTS 7

3. PROBLEM STATEMENT 9

4. STUDY AREA 10 4.1 Ermelo Mines Coal Discard Dump 12 4.2 Estancia Colliery Coal Discard Dump 13 4.3 Minnaar Colliery Coal Discard Dump 15 4.4 South Colliery a) Road Coal Discard Dump 17 b) Void Coal Discard Dump 19 4.5 TNC Coal Discard Dump 20

5. DATA GATHERING AND ANALYTICAL METHODS 23 5.1 Data sources 23 5.2 Method of data collection 23 5.3 Data gathered 26 5.4 Strengths and shortcomings of data 27 5.5 Analysis of data 27

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6. RESULTS 28 6.1 Ermelo Mines Coal Discard Dump 28 6.2 Estancia Coal Discard Dump 31 6.3 Minnaar Coal Discard Dump 34 6.4 South Witbank Ogies Road Coal Discard Dump 38 6.5 South Witbank, Void Coal Discard Dump 41 6.6 TNC Coal Discard Dump 44

7. DISCUSSION OF RESULTS 48 7.1 Difference Between the Six Coal Discard Dumps 48 7.2 Difference Between the Five Different Slope Aspects 53 7.3 Difference Between the Two Groups of Slope Angles 57 7.4 Difference Between Slope Angle and Slope Aspect 59

8. SYNTHESIS AND CONCLUSIONS 64 8.1 The Difference Between the Six Coal Discard Dumps 64 8.2 The Difference Between the Five Different Slope Aspects 65 8.3 The Difference Between the Two Groups of Slope Angles 65 8.4 The Relationship Between the Slope Angle and Slope Aspect 65

9. POSSIBLE RECOMMENDATIONS 66

10. REFERENCES 67

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LIST OF FIGURES

Figure 1: Coal forms eighty percent of the energy mix in . 1 Figure 2: This graph indicates the generation capacity and the demand in Southern Africa. 2 Figure 3: Locality map indicating the positions of Witbank and Ermelo in the Mpumalanga . 10 Figure 4: Locality map indicating the position of the various mines in relation to Witbank, Middelburg and Ermelo in the Mpumalanga Highveld. 11 Figure 5: Aerial photograph of the Ermelo Mines coal discard dump taken from the south shortly before the mine was closed. 12 Figure 6: Aerial photograph of the Ermelo Mines coal discard dump, taken from the northeast, five years after rehabilitation. 13 Figure 7: Aerial photograph of the Estancia coal discard dump, taken from the east, shortly before rehabilitation work commenced. 14 Figure 8: Arial photograph of the Estancia coal discard dump, taken from the west, eight years after rehabilitation. Dots are cows grazing on the western slope. 15 Figure 9: Aerial photograph of the Minnaar coal discard dump, taken from the southeast, shortly before rehabilitation work commenced. 16 Figure 10: Aerial photograph of the Minnaar coal discard dump, taken from the northwest nine years after rehabilitation. 16 Figure 11: Aerial photograph of the Ogies road coal discard dump, taken from the west, during the shaping process. 18 Figure 12: Aerial photograph of the Ogies road coal discard dump, taken from the southeast six years after rehabilitation. 18 Figure 13: Photograph of the Void coal discard dump in the background beyond the opencast void. 19 Figure 14: Aerial photograph of the Void coal discard dump, taken from the northwest, seven years after rehabilitation. 20 Figure 15: Aerial photograph of the TNC coal discard dump shortly before the mine was closed. Plant and office infrastructure can be seen. 21

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Figure 16: Aerial photograph of the TNC coal discard after rehabilitation. 21 Figure 17: The strike indicator indicating a basal as well as a ground level hit. 24 Figure 18: The magnetic angle finder position on the wooden plank. 25 Figure 19: The location and direction of the intersect lines on the Ermelo Mines coal discard dump. 28 Figure 20: The location and direction of the intersect lines on the Estancia Colliery coal discard dump. 31 Figure 21: The location and direction of the intersect lines on the Minnaar Colliery coal discard dump. 35 Figure 22: The location and direction of the intersect lines on the South Witbank Ogies Road coal discard dump. 38 Figure 23: The location and direction of the intersect lines on the South Witbank Void Colliery coal discard dump. 41 Figure 24: The location and direction of the intersect lines on the TNC coal discard dump. 44 Figure 25: Comparative graph of the basal cover of the different dumps. 49 Figure 26: Comparative graph of the plant litter cover of the different dumps. 51 Figure 27: Comparative graph of the bare ground of the different dumps. 53 Figure 28: Comparative graph of the different slope aspects for basal cover. 54 Figure 29: Comparative graph of the different slope aspects for plant litter cover. 55 Figure 30: Comparative graph of the different slope aspects for bare ground. 56 Figure 31: Comparative graph of the two groups of slope angles for basal cover. 57 Figure 32: Comparative graph of the two groups of slope angles for plant litter cover. 58 Figure 33: Comparative graph of the two groups of slope angles for bare ground. 59 Figure 34: Comparative graph indicating the means of the slope aspects with a change in slope angle for basal cover. 61 Figure 35: Comparative graph indicating the means of the slope aspects with a change in slope angle for plant litter cover. 62 Figure 36: Comparative graph indicating the means of the slope aspects with a change in slope angle for bare ground. 63

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LIST OF TABLES

Table 1: Key for aspect angles of the slopes. 26 Table 2: Data collected from the Ermelo Mines coal discard dump. 29 Table 3: Data of the north-facing slope of the Ermelo Mines coal discard dump only. 29 Table 4: Data of the east-facing slope of the Ermelo Mines coal discard dump only. 30 Table 5: Data of the south-facing slope of the Ermelo Mines coal discard dump only. 30 Table 6: Data of the west-facing slope of the Ermelo Mines coal discard dump only. 30 Table 7: Data of the top slope of the Ermelo Mines coal discard dump only. 31 Table 8: Data collected from the Estancia Colliery coal discard dump. 32 Table 9: Data of the north-facing slope of the Estancia Colliery coal discard dump only. 32 Table 10: Data of the east-facing slope of the Estancia Colliery coal discard dump only. 33 Table 11: Data of the south-facing slope of the Estancia Colliery coal discard dump only. 33 Table 12: Data of the west-facing slope of the Estancia Colliery coal discard dump only. 34 Table 13: Data of the top slope of the Estancia Colliery coal discard dump only. 34 Table 14: Data collected from the Minnaar Colliery coal discard dump. 35 Table 15: Data of the north-facing slope of the Minnaar Colliery coal discard dump only. 36 Table 16: Data of the east-facing slope of the Minnaar Colliery coal discard dump only. 36 Table 17: Data of the south-facing slope of the Minnaar Colliery coal discard dump only. 37 Table 18: Data of the west-facing slope of the Minnaar Colliery coal discard dump only. 37

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Table 19: Data of the top slope of the Minnaar Colliery coal discard dump only. 37 Table 20: Data collected from the South Witbank Ogies Road coal discard dump. 39 Table 21: Data of the north-facing slope of the South Witbank Ogies Road Colliery coal discard dump only. 39 Table 22: Data of the east-facing slope of the South Witbank Ogies Road Colliery coal discard dump. 39 Table 23: Data of the south-facing slope of the South Witbank Ogies Road Colliery coal discard dump only. 40 Table 24: Data of the west-facing slope of the South Witbank Ogies Road Colliery coal discard dump only. 40 Table 25: Data of the top slope of the South Witbank Ogies Road Colliery coal discard dump only. 41 Table 26: Data collected from the South Witbank Void coal discard dump. 42 Table 27: Data of the north-facing slope of the South Witbank Colliery Void coal discard dump only. 42 Table 28: Data of the east-facing slope of the South Witbank Colliery Void coal discard dump only. 43 Table 29: Data of the south-facing slope of the South Witbank Colliery Void coal discard dump only. 43 Table 30: Data of the west-facing slope of the South Witbank Colliery Void coal discard dump only. 43 Table 31: Data of the top slope of the South Witbank Colliery Void coal discard dump only. 44 Table 32: Data collected from the TNC coal discard dump. 45 Table 33: Data of the north-facing slopes of the TNC coal discard dump only. 45 Table 34: Data of the east-facing slopes of the TNC coal discard dump only. 46 Table 35: Data of the south-facing slopes of the TNC coal discard dump only. 46 Table 36: Data of the west-facing slopes of the TNC coal discard dump only. 47

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Table 37: Data of the top slopes of the TNC coal discard dump only. 47 Table 38: Contrast table indicating the significant difference of basal cover between dumps. 49 Table 39: Contrast table indicating the significant difference of plant litter cover between dumps. 51 Table 40: Contrast table indicating the significant difference of plant litter cover between dumps. 52 Table 41: Contrast table indicating the significant difference of basal cover between the various slope aspects. 54 Table 42: Contrast table indicating the significant difference of plant litter cover between the various slope aspects. 55 Table 43: Contrast table indicating the significant difference of bare ground between the various slope aspects. 56 Table 44: Contrast table indicating the significant difference of basal cover between the two groups of slope angles. 57 Table 45: Contrast table indicating the significant difference of plant litter cover between the two groups of slope angles. 58 Table 46: Contrast table