An Investigation of the Environmental Impact of Surface Diamond Mining along the Arid West Coast ...

216 Pages·2014·3.8 MB·English

AN INVESTIGATION OF THE ENVIRONMENTAL
IMPACT OF SURFACE DIAMOND MINING
ALONG THE ARID WEST COAST OF SOUTH AFRICA
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by
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Wolfgang F.M. Talkenberg
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A thesis submitted in partial fulfilment
of a Master of Science degree in the
School of Environmental Studies,
University of Cape Town·
September 1982
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The copyright of this thesis vests in the author. No
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quotation from it or information derived from it is to be

published without full acknowledgeement of the source.
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The thesis is to be used for private study or non-
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commercial research purposes only.

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Published by the Universit y of Cape Town (UCT) in terms
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of the non-exclusive license granted to UCT by the author.
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ABSTRACT
An outline of the main features of the West Coast environment establish
es that it has potential value for recreation, tourism and nature con
servation, in addition to that of diamond mining, and that it is
sensitive to disturbance. The diamond'mining process is analysed
and mining actions that cause environmental impact are identified. A
matrix approach ls employed to relate particular mining actions to
specific environmental elements. It is found that there is major
impact on scenic and vegetation elements and that primary impact is
magnified significantly through the process of wind erosion. It is
argued that much environmental impact can be prevented if the object
ive of environmental protection was incorporated into the management
of mine sites and that unavoidable impact can be mitigated by rehabi
litation, which is a reasonable requirement.
ii
Tha.t fund y-i.e.ld-0 a. c.u.f.twr.a..f. haJtvut ti
a. 6a.c.:t long I-mown; bu.:t .f.a.:t:tvr.ltj o6:te.n
fioJt.go:tt.eri
- Aldo Le..opold
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TABLE 'OF CONTENTS
Page
LIST OF TABLES AND FIGURES AND MAP vii
ACKNOWLEDGEMENTS ix
PREFACE x
CHAPTER INTRODUCTION
Introduction to the Topic
Scope and Terms of the Investigation 3
Objectives of this Investigation 5
Approach to the Investigation 6
CHAPTER 2 THE WEST COAST ENVIRONMENT
Introduction 9
The Physical and Biological Environment 10
Topography lb
Geomorphology and Geology 12
Vulnerability of the Coastal Foreland 13
Soi ls 15
Climate 17
General 17
Radiation 18
Temperature 19
20
Precipitation
Winds 21
Vegetation 29
Fauna 33
Rivers and Estuaries 34
Ground \foter 35
Marine Environment 36
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The Socio-economic Environment 37
Archaeological and Historic Sites 37
Present Population 38
Infrastructure 39
Resource Use 40l
40 I
Marine Resources
Agriculture 42
Recreation, Tourism and Nature Conservation 4?_)!
Mining 49
Summary 52 \
Sensitivity of the West Coast Environment 52_J
Value of the West Coast Environment 55
CHAPTER 3 THE MI N I NG ACTIONS
Background Information 57
Introduction 57
Geology of the Diamond Deposits 58
General 58
Coastal Terrestrial Deposits 59
River Deposits 63
Marine Deposits 64
History of Exploitation for Diamonds along the
West Coast 65
Past Exploitation on tand 65
Past Marine Exploitation 67
Present Exploitation 68
The Mining Actions 74
Introduction 74
Mining Actions by the Large Enterpdses 75
Prospecting 75
The Mining Operation 81
Treatment of Diamondiferous Gravels 86
Induced Actions 90
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Developed Infrastructure 92
Future Mining Actions 94
Mining Actions of Selected Smaller Enterprises 95
DBCM Inland Operation 95
Small Companies near Olifants River 96
Marine Mining Operations 98
Summary 100
CHAPTER 4 ENVIRONMENTAL IMPACT
Introduction 104
Environmental Impact of Large Enterprises 105
The Matrix Approach 105
Discussion of lmpacti 109
Wind Erosion 128
Natural Revegetation 133
Environmental Impact of Smaller Enterprises 141
OBCM Inland Operation 141
Smaller Companies riear Olifants River 142
Marine Mining 144
Summary 145
CHAPTER 5 REHABILITATION
Introduction 148
Reasons for Rehabilitation 150
Magnification of Impacts 150
Future Land Use 151
Ethics, Public Opinion and Economics 152
Present Situation 155
Present Rehabilitation Measures 155
Natural Rehabilitation 156
Benefits of Rehabilitation for Mining Enterprises 157
Public Image 157
lnhouse Benefits 159
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Practical Aspects of Rehabilitation 159
Feasibility of Revegetation 159
Suggested Rehabilitation Actions 163
Financial Feasibility 169
Summary 173
CHAPTER 6 CONCLUSION 176
REFERENCES 178
APPENDIX A Definitions of Elements of Impact Matrix
189
APPENDIX B Data Source for Determining Total Area
of Mining-disturbed Land 190
APPENDIX C Investigation of Sand Plume Spread 191
APPENDIX D Analysis of Soil Samples 192
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LIST OF FIGURES, TABLES AND MAP
Page
Fig. 2. 1 Vulnerability of the coastal foreland. 14
Fig. 2.2 Wind roses. 23
Fig. 2.3 Diurnal variation of speed and direction of wind
resultants at Alexander Bay. 24
Table 2.4 Annual wind parameters along the West Coast of
southern Africa. 25
Fig. 2.5 Annual sand roses, Cape Town to Walvis Bay. 26
Fig. 2.6 Latitudinal variation in annual resultant drift
potential, Cape Town to Walvis Bay. 27
Fig. 2.7 Vegetation zones on the West Coast. 30
Table 2.8 GGP according to economic sector of Namaqualand. 49
Table 2.9 Diamond sales West Coast, 1975-1980. 50
Fig. 2. 10 West Coast diamond production compared to South
Africa and world for 1980. 51
Fig. 2. 11 Diamond sales of West Coast and South Africa in
1979. 51
Fig. 3. 1 Typical stratigraphy of sediments al·ong West Coast. 61
Fig. 3.2 Diamond mining zones. 69
MAP 1 Land allocated to diamond prospecting and mining. 70
Table 3.3 Total diamond production from the West Coast 72
Fig. 3.4 Diamond production share of mining enterprises. 73
Fig. 3.5 Diamond production share of land and sea 73
concessions.
Fig. 3.6 Prospecting trench system. 79
Fig. 3.7 Auger drilling grid. 79
Table 3.8 Overburden stripped by SAO and DBCM. 82
Table 3.9 Area disturbed by mining through primary actions. 85
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Fig. 3. 10 Diamond mine treatment process 88
Table 3. 11 Treatment plants in use and abandoned by SAD and
DBCM. 89
Table 3. 12 List of mining actions. 102
Table 4. 1 Impact matrix. 108
Fig. 4.2 Action-effect network. 129
Table 4.3 Land area disturbed by mining. 131
Table 4.4 Expansion of sand plume areas on SAD land. 132
Table 4.5 Natural revegetation at SAD. 136
Table 4.6 Natural revegetation at Annex Kleinzee WBCM). 139
Fig. 5. 1 Possible control of wind erosion. 166
Fig. 5.2 The use of perimeter tipping to reduce visual 166
intrusion.
Table 5.3 Estimated mine revenue per hectare. 171
Fig. 5.4 Increase of West Coast diamonds in rand value
per carat. 172