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The Impact ofthe Gold Mining Industry on the Water Quality of the Kromdraai Catchment·

by

JOeL D. MALAN

MINI-DISSERTATION

Submitted in partial fulfilment of the requirements for the degree

MASTER OF SCIENCE

IN GEOGRAPHY AND ENVIRONMENTAL MANAGEMENT in the FACULTY OF SCIENCE

at the

RAND AFRIKAANS UNIVERSITY

SUPERVISOR: DR. P.J. WOLFAARDT

SEPTEMBER 2002 11

LIST OF CONTENTS

OPSOMMING , IV

SUMMARY VI

ACKNOWLEDGEMENTS Vlll

CHAPTER 1: INTRODUCTION 2 1.1 Project motivation for this study 4 r.a Purpose and objective ofthis study 5 1.3 Study Area 6

CHAPTER 2: NATURAL CATCHMENT CHARACTERISTICS 9 2.1 INTRODUCTION 9 2.1.1 General Description and relief 9 2.1.2 Geology and soils 10 2.1.3 Climate 11 2.1.4 Natural Vegetation 11 2.1.5 Hydrology 12

2.2 GENERAL IMPACTS ON WATER QUALITY 12 2.2.1 Geohydrology 13 2.2.2 The History of the quality of the dolomitic water in the 14 Far West Rand with special reference to the formation ofsinkholes 2.2.3 Water Cycle of a dolomitic Compartment 16 2.2.4 Effect ofDolomitic Water on Mining 19 2.2.5 Different issues associated with the I-m pipeline 22

2.3 Identification ofManagement Units 24

2.4 Conclusion 28 III

CHAPTER 3: QUALITY STATUS OF SURFACE WATER 30 3.1 Introduction 30

3.2 Pollution sources in the Kromdraai catchment 31

3.3 Analysis ofthe water quality data 33 3.3.1 Turffontein Eye 35 3.3.2 Wonderfonteinspruit at Gemsbokfontein (Beginning of 44 1-m pipeline) (C2H025) 3.3.3 Wonderfonteinspruit at Exit of 1-m pipeline (C2H080) 46 3.3.4 Driefontein Transverse Canal at Rooipoort (C2H063) 47 3.3.5 Wonderfonteinspruit at Abe Baily (C2H175) . 49 3.3.6 Doornfontein Canal at Blaaubank (C2H060) 50 3.3.7 Mooi River at Blaaubank (C2H069) 52 3.3.8 Mooi River at Kromdraai (C2H085) 53

3.4 Conclusion 55

CHAPTER 4: CONCLUSIONS AND RECOMMENDATIONS 58

4.1 Conclusions 58

4.2 Recommendations 59

REFERENCES 65

APPENDIX 1 70

APPENDIX 2 72 iv

OPSOMMING

Een van die hoofdoelwitte van die Nasionale Waterwet (Wet 36 van 1998) is om die natuurlike hulpbronne (veral water) te beskerm en teen besoedeling en misbruik te bewaar. Die waterbronne moet beskerm word vir die gebruik deur huidige en toekomstige geslagte, met ander woorde die volhoubare gebruik van water.

In hierdie studie is gekonsentreer op die Kromdraai-opvangsgebied wat die Bo-Wonderfonteinspruit, Onder-Wonderfonteinspruit, Loop­ spruit en Mooirivier insluit. Hierdie gebied word veral gekenmerk deur 'n groot aantal goudmyne wat 'n negatiewe invloed op die water kwaliteit van die gebied kan uitoefen.

Die doel van hierdie studie is om die invloed van goudmyne op die kwaliteit van waterbronne in die Kromdraai-opvangsgebied te ondersoek. Groot hoeveelhede waterkwaliteitsdata is versamel vanaf sekere moniteringspunte in die onderskeie sub-opvangsgebiede. Hierdie data is verwerk en sekere tendense is grafies voorgestel.

Die sulfaat konsentrasies, totale opge1oste soute en die elektriese geleidingsvermoe van die onderskeie watermonsters is bepaal om die besoedelingvlakke te bepaal. Om tyd en kostes te bespaar is daar egter besluit om slegs op die elektriese geleidingsverrnoe van die watermonsters te konsentreer, omrede dit 'n goeie aanduiding is van die besoedelingsvlakke in die spesifieke monster. Tendense is bepaal en gevolgtrekkings is gemaak om die invloed van die goudmyne op die waterkwaliteit te bepaal.

'n Duidelike invloed van 'n slikdam op die Turffontein Oog is waargeneem toe die elektriese geleidingsvermoe daarvan skerp gestyg v

het, terwyl Doornfontein goudmyn groot hoeveelhede slik op die. slikdam gestort het. Die elektriese geleidingsverrnoe van die Turffontein oog het weer begin daal nadat die storting van groot hoeveelhede slik gestaak is.

Die gevolgtrekking van die studie is, dat goudmyne wel In negatiewe invloed op die kwaliteit van die waterbronne in die Kromdraai­ opvangsgebied het. Hierdie negatiewe invloed kan slegs deur effektiewe geintegreerde omgewingsbestuur beheer en verminder word. Die toegang tot alle data deur alle belanghebbende partye is van kritieke belang, omrede die meeste aangrensende goudmyne mekaar direk impakteer deur die onttrekking en vrylating van groot hoeveelhede ondergrondse water.

Opvangsgebiedforums is gestig om alle belanghebbende partye te betrek wat In belang het by die geintegreerde omgewingsbestuur van die Kromdraai opvangsgebied. Die forums dien ook as voorlopers vir die opvanggebiedbestuursagentskap wat in die Bo-Vaal Water­ bestuurgebied gestig gaan word. vi

SUMMARY

One of the main objectives of the National Water Act (Act 36 of 1998) is the protection of natural resources (water resources) against pollution and misuse. These resources must be protected for the sustainable use by future and present generations.

The study area consisted of the Kromdraai Catchment which included the Upper Wonderfonteinspruit, Lower Wonderfonteinspruit, Loop­ spruit and the Mooi River. This area is known for the amount of gold mining activities which may have a negative influence on the " environment and especially on water.

The aim of this study is to determine the impact of the gold mining industry may have on the water quality of the Kromdraai Catchment. Huge volumes of water quality data were collected from certain major monitoring stations throughout the Kromdraai catchment. A good indicator of pollution in a water sample is the electrical conductivity (Ee) of the sample. EC values were used to determine the pollution in each of the water samples because it saves time and costs. Pollution trends were established and conclusions were drawn to determine the impact of the gold mines on the water quality.

A clear impact of a tailings dam on the water quality of the Turffontein Oog was established by the sharp increase in the EC values since the Doornfontein Gold Mine started depositing huge volumes of slime on the no. 3 tailing dam. The EC values of the Turffontein Oog have started to decline when the depositing of the slime was ceased. :.

The conclusion of the study is that the gold mining industry has a definite negative impact on the water quality of the water resources in vii

the Kromdraai catchment. The only effective way to mitigate and, manage these negative impacts, is through integrated environmental management. The sharing of data by all interested and affected parties is of critical importance, since most neighbouring goldmines are directly impacting on each other through the pumping and discharging of huge volumes of mine water.

Catchment forums were established for the integrated environmental management of the Kromdraai catchment by all interested and affected parties. These forums have become important bodies representing stakeholders in the establishment of catchment management authority (CMA) that Will be established in the Upper Vaal Water Management Area. viii

ACKNOWLEDGEMENTS

I wish to thank the following persons and institutions for their contributions towards this study:

• My wife Linda, for her unselfish support and patience;

• Dr. Leslie Stoch for his help with the interpretation of the

graphs and for his motivation and interest in the study;

• Dr. Peets Wolfaardt for his help and patience with this study;

• The Department of Water affairs and Forestry for financial

support and for the use of the water quality data;

• Heidi Munien for the GIS work and the printing of the maps;

• My Heavenly Father who gave me the strength to finish what

I've started. 1

There is water within us, let there be water with us. Water never rests. When flowing above, it causes rain and dew. Whenflowing below itforms streams and rivers. Ifa way is madefor it, itflows along that path. And we want to make that path. We want the water of this country to flow out into a network - reaching every individual saying: here is water for you. Take it; cherish it as affirming your human dignity; nourish your humanity. Water - gathered and stored since the beginning oftime in layers ofgranite and rock, in the embrace ofdams, the ribbons ofrivers - will one day, unheralded, modesty, easily, simply flow out to every South African who turns a tap. That is my dream (Krog, 1997). 2

CHAPTER 1: INTRODUCTION

In a speech to the National Assembly on the second reading of the National Water Act (Act 36 of 1998)(DWAF, 1998a) on Tuesday 9 June 1998, Prof. Kader Asmal, Minister of Water Affairs and Forestry, said:

" Water as a resource is fundamental to our economic lives; it sustains our . agriculture, drives the turbines of our power points, cools and cleans the mines, heats our offices, catalyses the process of our manufacturing industry; washes down our taverns. And it will continue to do this.

Our water policy says that our aim in managing water is not just to ensure equitable access to the resource, not a crude dividing up of so many buckets per person. Our aim is to extract and exact the maximum benefit to society from its use. We are charged together, to make wonderful music with the instruments our water allows us (Asmal, 1998).»

The natural resources of a country determine to a large extent the activities of its population. A shortage of any particular resource, especially water, without which no man or beast can survive, will ultimately set a limit to the general development of that country. A resource will be of maximum benefit or service only if it is conserved and used as efficiently as possible (Enslin, 1964).

The constitution of South Africa is the most important piece of legislation in South Africa and therefore a very important tool to use for environmental management. In section 24 of the Act (Constitution of South Africa, 1996), the Environment is described in accordance to the constitution, where it is stated that: Everyone has the right - • to an environment that is not harmful to their health or wellbeing; and • to have the environment protected, for the benefit of present and future generations, through reasonable legislative and other measures that - 3

(i) prevent pollution and ecological degradation; (ii) promote conservation; and (iii) secure ecologically sustainable development and use of natural resources while promoting justifiable and social development (Constitution of South Africa).

The principles of pollution prevention and sustainable development, two of the cornerstones of environmental management, especially water quality management, are enshrined in the Constitution by their inclusion in this section. The principle of sustainable development is defined as the right of future generations to have the same quality of life and access to natural resources as the present generation (DWAF, 1998).

The National Water Act (Act 36 of 1998) was written in line with the Constitution to protect the natural (water) resources and to ensure sustainable development and to prevent pollution of these natural resources.

The ultimate aim of the National Water Act (Act 36 of 1998) is:

• To achieve the sustainable use of water for the benefit of all users; • The protection of the quality of water resources is necessary to ensure sustainability of the nations water resources in the interest of all water users; • Recognising the need for the integrated management of all aspects of water resources and where appropriate, the management functions to a regional or catchment level so as to enable everyone to participate (DWAF, 1998).

Human development and the utilization of water are interactive. As the population increases exponentially over time, so the dependence on a limited resource increases. As pressure for settlement land moves further 4

and further away from existing centers, so the need to distribute, water over wider areas increases.

As the population increases, so development must increase to keep pace and supply this growing population with its needs. This may be industrial, mining, agricultural, or recreational need and each in turn requires a . share of the water resource. During this process, the volume of water may be reduced and the quality of water may deteriorate. It is therefore fundamental that the water resource is managed in such a way as to sustain human development, for the benefit of all the communities, the ecological environment and to satisfy basic human need.

The National Water Act (Act 36 of 1998) provides the framework for the management of the water resources of the country for the future. This framework requires that the water resources are understood and that all the key stakeholders are involved in the development of management strategies.

To adhere to the spirit of the National Water Act (Act 36 of 1998), the protection of the natural resources in the Kromdraai catchment is of great importance. In order to protect these natural resources, it is important to obtain as much water quality and quantity data as possible and to determine the impact that the gold mining industry has on these natural resources. These natural resources include all major rivers, dams, underground water and dolomitic compartments (aquifers).

1.1 Project Motivation Cor the study

Mining activities have occurred in the Far West Rand" area since 1935. Gold bearing ore are being mined in the rock layers known as the Witwarersrand Super-group, which is situated beneath dolomitic layers. As mining activity on the Witswatersrand increased from the turn of the 5

century, so did the contamination by dissolved solids, largely calcium sulphate, in the effluent entering the Vaal River (Marsden, 1986).

As the mines developed, increasing quantities of sulphate-contaminated water were pumped from underground. This has led to salination of both the downstream river system and the underlying dolomitic water resource, adversely affecting beneficial water use. The complexity of the network of mine water disposal systems is compounded by the interaction between surface streams and dolomitic groundwater compartments that they transverse. Dolomite aquifers represent the most important groundwater resource in South Africa. They are, however, subjected to a multitude of impacts from activities such as mining, agriculture and informal settlements, amongst others (Bredenkamp, 1995).

1.2 Purpose and Objective of this study

The purpose of this study is to investigate the impact of gold mining on water quality. The objective of this study in particular will be to investigate the impact of the gold mining industry on the water quality in the Kromdraai catchment, through the analysis of water quality data from specific key monitoring points.

The impact of discharged water pumped from underground, as well as the possible impacts of slimes dams on the quality of receiving water bodies, will be investigated in this research.

Chapter 1 is the introduction to the Kromdraai catchment and the need to protect the natural (water) resources. Chapter 2 describes the natural catchment characteristics and the problems associated with excess dolomitic water. The quality status of the surface water is analyzed In Chapter 3 with the conclusion and recommendations in Chapter 4. 6

1.3 Study Area

, The Kromdraai catchment was used for the purpose of this study because the West Rand is one of the most active gold mining areas in South Africa and large volumes of water quality and quantity data is available from this catchment. This catchment consists of the Upper Wonderfonteinspruit, Lower Wonderfonteinspruit, Loopspruit and the Mooi River.

The Mooi River, Wonderfonteinspruit and Loopspruit run through the magisterial districts of Krugersdorp, Randfontein, Westonaria, Oberholzer, Fochville and Potchefstroom (Figure 1.1.).

The Mooi River originates above Bovenste Eye in the Mathope~tad area, while the Wonderfonteinspruit originates around the mine waste tips of the West Rand Consolidated Gold Company, south of Krugersdorp and east of Randfontein. The Loopspruit originates upstream of Fochville.

The Mooi River is a tributary of the Vaal River in the Upper Vaal Water Management Area, which constitutes an important component of the Vaal River System (DWAF, 2000).

The yellow, green and dark pink areas In Figure 1.1 indicate the Kromdraai catchment with the Mooi River, Loopspruit and Wonderfonteinspruitjoining the Vaal River near Potchefstroom.

Various mines are situated in the Wonderfonteinspruit catchment and in the Loopspruit catchments. The ten operational mines in the Kromdraai catchment are indicated in Table 1 with the catchments they are discharging to.

8

Table1: The Ten Operational Mines in the Kromdraai catchment with the companies they represent and the catchments these mines discharge to.

~- ~ ~ ' - - - ~----r ~ ~ - ~' ~~. ~- -J J~i~(£ ~1o WiITf~ _ jl (;~'7" .' _,.= .. : ' _ .... __ .____ .> ~,.,._ Kloof Gold Mine Goldfields Limited Loopspruit Venterspost Gold Goldfields Limited Wonderfonteinspruit Mine Libanon Gold Mine Goldfields Limited Wonderfonteinspruit Blvvooruitzicht Durban Roodepoort Deep Wonderfonteinspruit Driefontein Goldfields Limited Wonderfonteinspruit Consolidated Mponeng Anglogold Limited Wonderfonteinspruit & Loopspruit Deelkraal Harmony Gold Wonderfonteinspruit & Loopspruit Elandsrand Harmony Gold Wonderfonteinspruit Savuka Anglogold Limited Wonderfonteinspruit Tautona Anglogold Limited Wonderfonteinspruit 9

CHAPTER 2: NATURAL CATCHMENT CHARACTERISTICS

2.1 INTRODUCTION

This chapter explains the natural characteristics and the relief of the Kromdraai catchment. The geology and soils of this area are described, as the geology of a certain area determines the water quality of that area. In

dolomitic rock formations, the calcium:magnesium ratio In the groundwater will be high as dolomitic rock formations consists mainly of these ions.

The second part of the chapter describes the geohydrology and the problems associated with the pumping of excess water from underground.

2.1.1 General Description and relief

The Kromdraai catchment is relatively flat with elevations varying between 1520m in the north, to about 1300m in the vicinity of the Vaal River confluence. The Witswatersrand ridge forms the drainage divide between the Vaal and the Crocodile River catchments areas. The relief of a catchment will influence the amount of water that will infiltrate into the ground at any given time. Areas with a steep slope will have more runoff of surface water that flat areas.

The originally gently undulating relief of the Upper Wonderfonteinspruit catchment has been considerably modified by mine dumps that are conspicuous topographic features.

A steep rocky ridge, known as the Gatsrand, runs East/West through most of the mining area in the Lower Wonderfonteinspruit catchment. The area in general is rocky on the ridges, slopes and flat areas. Most of the mines in the area have a relatively flat to undulating relief. East 10

Driefontein's northern relief is flat, with the Gatsrand rising to an elevation of 1740m in the south (East Driefontein EMPR, 1996).

The flat relief of the Lower Kromdraai catchment results in the river having a moderate slope of 1.7m/krn (0,17%). The average slope of the Mooi river between Boskop Dam and Potchefstroom is 2,5m/km (0,25%) and between Potchefstroom and the Vaal River the slope is 0,9m/km (0.9%), which explains the extensive wetland areas downstream of Potchefstroom (CSIR, 1991).

2.1.2 Geology and soils

In the Upper Wonderfonteinspruit, the northern higher part situated in a portion of the First West Gold property is underlain by predominantly arenaceous rocks of the Witwatersrand Super-group. The south eastern portion of the First West Gold property is underlain by deeply weathered basic intermediate lavas of the Ventersdorp Super-group that are characterised by an extensive cover of residual red soils. The central and south-western portions are underlain by basal sediments of the Transvaal sequence that comprise alternating red and green shales, with intercalated beds of quartzite.

The infrastructure of the majority of mines In the Lower Wonderfonteinspruit has been established on land that has low agricultural potential as a result of shallow rocky soils. The mines that have been developed along the Gatsrand ridge, have thus disturbed agricultural areas with grazing potential. Neither the top of the Gatsrand ridge nor the steep sided slopes of the ridge have an arable potential, but the more gently sloping undulating areas to the south have deeper soils / with an arable potential. A few small wetland areas, predominantly forming during the rainy season, adjoined the occasional small spruit draining the ridge (Kloof Gold Mine EMPR, 1994). 11

In the Lower Wonderfonteinspruit and Loopspruit catchments Kloof, Leeudoorn and Deelkraal Gold Mines are entirely situated on Pretoria Group rocks. Towards the southern sides of Kloof and Deelkraal Gold mines, the Pretoria Group rocks attain a maximum thickness of 100m and 850m respectively. Occurrences of the younger Karoo-age shales, sandstones, and coal seams of the Ecca Group and tillite of the Dwyka Formation are found in depressions in dolomite. These rocks attain a thickness of up to 50Om in places. Occurrences of the Karoo rocks are found on Libanon, Driefontein Gold Mine (Leeudoorn Gold Mine EMPR, 1996).

2.1.3 Climate

The climate in the area is typical of the Southern African Highveld, with warm to hot summers and warm sunny winter days with frosty nights. Rainfall occurs predominantly during the summer months in the form of thunderstorms associated with lightning and occasional hail.

The mean annual rainfall ranges from about 750mm on the north-eastern boundary of the study area to about 520mm in the vicinity of Boskop Dam. The mean annual, potential catchment evaporation in the study area varies between 1600 and 1700 mm (Pulles Howard & de Lange, 1999).

2.1.4 Natural Vegetation

Grassland originally covered virtually all of the catchment, but much of the area is now under cultivation, mostly maize. According to Acocks (1988) the general vegetation of the catchment is sour grassveld with mixed grassveld close to Potchefstroom. In the Loopspruit, Kloof Gold Mine and Minrec Gold Mine both fall within the Bakenveld western Variation veld type, which consists of a typical sparse, tall, tufted grass 12

component with trees and shrubs occumng on rocky outcrops and protected areas (Acocks, 1988).

Generally, the upper reaches of the Wonderfonteinspruit are covered by grassland with minor shrub manifestations. Exotic tree species are developed in clusters, mainly surrounding the dump areas. This vegetation was originally introduced to screen the mine dumps from . surrounding areas and comprises predominantly eucalyptus and black wattle (Leeudoorn Gold Mine EMPR, 1996).

2.1.5 Hydrology

The mean annual run-off for the Mooi River at its confluence with the Vaal river and at the Boskop Dam have been calculated as 122 x 106 m3 and 72 x 106 m3 respectively for the period 1920 -1994 (DWAF, 1997).

The various dams in the catchment include the Attenuation Dam, Donaldson Dam, Harry's Dam, Klipdrift Dam, Klerkskraal Dam and Potchefstroom Dam. The Klerkskraal and Boskop Dam and Potchefstroom Dam provide domestic and industrial water supplies for Potchefstroom through the Mooi River State Water Scheme.

2.2 GENERAL IMPACTS ON WATER QUALITY

The Kromdraai catchment has very unique geological characteristics that influence the water quality of the area. It will be explained below that huge volumes of groundwater must be pumped from underground to sustain the mining of gold in the Far West Rand. If this dolomitic water comes into contact with the exposed mining surface area, it becomes heavily polluted. Mine process water is known to have a pH of 2-3' and a sulphate concentration of up to 2000mg/1. This polluted water may not be discharged to the environment and must be contained on site or treated to 13

improve the quality before discharging into the drainage system of the Kromdraai catchment.

2.2.1 Geohydrology

The study area is divided into geohydrologic units (compartments) defined by hydrologic boundaries such as impermeable igneous dykes (Enslin, .1964) (See Figure 2.1.). Most of the area is underlain by dolomite. The dolomite occurring in the area has been subjected to at least four periods of karstification and erosion during the last 2000 million years and a well connected network of caverns, faults and joints which have been widened by solutions, has formed. The karstified dolomite acts as an aquifer (van Wyk & Louw, 1993).

Our present knowledge of the groundwater occurrences of South Africa ­ the characteristics of aquifers, the quantities of stored ground water, the annual recharge of the supplies, the quality of the water and the methods of tracing and developing the supplies- is not sufficient to enable us to assess the available supplies and their safe yields to serve as a basis for the planning and control of the conservation and utilisation of those resources (Enslin, 1964).

Groundwater occurs in the inter-connected conduits within the dolomite. The dolomitic area extends from the Klip River south of Roodepoort, to the Boskop Dam north of Potchefstroom and consists mainly of the valley of the Wonderfonteinspruit (Schwartz & Migley, 1975). 14

... ..:

,.,:1 "

.!

T U RFFO NT EIN KO MPAR TEMENT ! W ON 0 E

Figure 2.1: Dolomitic Compartments in the Far West Rand (Cartwright, 1970).

The major dolomitic compartments such as Turffontein, Oberholzer, Bank and Venterspost in the Far West Rand, are schematic illustrated in Figure 2.1 in relation with the Carletonville, Westonaria and gold mines in the area.

2.2.2 The History of the quality of the dolomitic water in the Far West Rand with special reference to the formation of sinkholes.

The formation of sinkholes and ground subsidence is a well known phenomenon in dolomitic areas and is due to very slow natural processes. In the Far West Rand, the surface manifestations of these processes have been accelerated by dewatering of the dolomitic compartments resulting from gold mining operations (Keersmaekers & Aldridge, 1967).

The Far West Rand dolomitic area fell within an underground water­ controlled area, consequently the discharge of underground mine water was restricted to areas located within the compartment from which the water originated. This procedure gave nse to huge amounts of 15 underground water being recirculated through the mines which resulted in increased dissolution of the dolomitic formations due to continuous exposure of dolomites to water enriched in carbon dioxide and sulphuric acid (McKenzie, 1989).

Owing to the high pumping costs, the risk involved by possible flooding of mines during power failures and the limitations placed on mining operations at great depth, the Interdepartmental Committee for dolomitic water recommended that the restrictions on the discharge of underground . water be lifted and that the Venterspost and Oberholzer dolomitic compartments be dewatered (Jordaan et al., 1960).

Ground water in the dolomite series, which is probably the most important aquifer in South Africa, is stored in well defined compartments or reservoirs with "walls" consisting of less permeable sediments of the underlying black reef series, the overlying Pretoria series and diabase dykes which cut through the dolomite (Enslin, 1964; McKenzie, 1989).

It has been estimated that the storage capacities of the Oberholzer and Venterspost compartments, two of the larger ground water compartments, are 720 000 MI and 450 000 MI respectively. These capacities are thus of the same order as the full supply capacity of the larger irrigation dams in South Africa (Enslin, 1964).

The water level in each compartment is relatively flat or nearly horizontal. Its height is controlled by the level of an eye or spring, which occurs at the western end of each compartment. The eye emerges at ground surface at the position where the dyke intersects the deepest drainage feature in the area, namely the Wonderfonteinspruit (Enslin, 1964). 16

2.2.3 Water Cycle ofa dolomitic compartment

It has long been realised that ground water in dolomite is contained, in an extensive network of fissures, cavities and channels formed by the solution of the rock by water containing carbonic acid, and that over large areas these water bearers are interconnected (Jordaan et al., 1960).

The water in a dolomitic compartment is thus contained in a large . underground reservoir. If it is accepted that its floor and walls are impervious and recharge to the compartment is sufficient to keep it full, the storage basin will overflow at the lowest points of its impervious boundaries (Foster, 1989).

In the Far West Rand the systemic dykes which separate the compartments were impervious. The Venterspost compartment was de­ watered by 1949 and the Oberholzer Compartment by 1959. The term "de­ water" means that the eye that supplies the compartment with water, has ceased to flow. The water table could then have dropped several meters below its original level. Thus, there is still water in these compartments, but the water table has dropped considerably. The eyes are not flowing due to the low water levels in the compartments. These compartments were bordered by the Gemsbokfontein compartment in the east, the Bank compartment in the middle and the Turffontein compartment in the west (McKenzie, 1989).

The foregoing explains the occurrence of the eyes at the lowest points of the dykes in the Far West Rand. Recharge of ground water to such a dolomitic compartment takes place in one or more of the following ways:

(i) Rainfall in the catchment which percolates through the dolomites to the water table. Measurements over a period of fifty years has shown that the average flow of the Steenkoppies Eye, which is actually the effluent 17 seepage of groundwater recharged by rainfall on the Steenkoppies Compartment, to the north of the area, is equivalent to 10,6% of the mean annual rainfall on this compartment (Jordaan et al., 1960). The major portion of the rainfall on the dolomite is therefor lost by evaporation and transpiration and surface flow after the thunderstorm events.

(ii) Influent seepage from beds of canals and rivers crossing the dolomite. (iii) Influent seepage of runoff from non-dolomitic areas on to dolomite.

(iv) Surplus irrigation water which has percolated to below the root zone of crops irrigated on dolomite. (v) Leakage underground from higher-lying compartments.

Losses from stored ground water takes place in one or more of the following ways:

(i) The normal flow of the dolomite Eye of the compartment at the point where it crosses the ground-Eye barrier. (ii) Water pumped from underground and then lost to the compartment. Water which finds its way back into the compartment is thus excluded. (iii) Leakage through dykes forming the boundaries.

Under natural conditions, the total flow of the Eye over a long period will be equal to the difference between the natural recharge and ariy losses from ground water which occur before the Eye is reached (Bredenkamp et al., 1991).

From the above it is· obvious that if more water is pumped from, and thus lost to the compartments that is recharged, the water table will be lowered until it reached a level lower than the overflow at the eye, and then the latter will dry up. This was experienced at Klip River Eye in 1938, Venterspost Eye in 1949, Wonderfontein Eye in 1959 and at the Oog van Wonderfontein in 1969. 18

The time, which elapses before the flow of the eye is affected, depends on the rate of dewatering, the quantity of water stored in the compartment above the outlet level and the distance between the dewatering point and the eye (Foster, 1989).

After artificial dewatering of a compartment has ceased, the compartment will refill until the water table reaches the level of the eye before the eye will start flowing again. The level has to be raised still further before the normal flow of the eye will be restored (Campbell & Basson, 1986)

Where mmmg has taken place and the barriers between the compartments were breached, this may not happen. Wolmarans (1984) suggests a mega-compartment discharging at the Turffontein Eye will be established. Kleywecht (2001) rejects this theory by arguing that the flow will be dictated originally by the eyes and as the head between the upper and lower compartments is not large, the flow tempo through the dykes will be limited (Foster, 1989; Bredenkamp et al., 1991).

From the above the problem associated with the disposal of water pumped from mines is evident. If the water pumped from a compartment is returned, the water table in the dolomite will not be lowered and the flow of the eye will not be affected. Because some of the pumped water is lost by evaporation, and as the mines are entitled to use some of the water for mining operations, the flow of the eye will decrease in course of time. If, in addition, the mines are allowed to discharge the water pumped from underground outside the compartment, the water table will drop and the compartment will ultimately be de-watered. This was the policy agreed by the State in 1963 for the Venterspost and Oberholzer Compartments, in 1968 for the Bank compartment and in 1986 for the Gemsbokfontein compartment. 19

2.2.4 Effect of Dolomitic Water on Mining

The economically important gold and uranium ores of the Far West Rand occur in conglomerate and quartzite reefs in the Upper Division of the Witwatersrand Super-group and in the conglomerate which forms the floor of the Ventersdorp Super-group (Wolmarans, 1985).

To reach the reefs, shafts have to be sunk through the dolomite and black reef. Water from the dolomite percolates and finds its way through fissures and fault panes into the stopes. Originally the Bank compartment was considered to be too large to dewater. West Driefontein Gold Mine mined . through the dyke from West to East into the Bank Compartment (Thomas, 1968).

If the water pumped from the mines were to be put back into the compartment, the water level will remain more or less constant and the danger of inrushes of water would increase as the stope areas increased. If the pumped water can be delivered outside the compartment the compartment will gradually de-water. The water table was lowered progressively and the water pressure, which causes the inflow of water into mines, decreased. Thus the quantity of water to be pumped also decrease progressively (Foster, 1989).

Stander (1964) stated that the de-watering of the Venterspost and Oberholzer compartments wouldn't have immediate negative effects. But as soon as the mining activities stop, these compartments will start to fill up with polluted water, mineralized and acid water. It can thus be expected that the dolomites will be eroded away and sinkholes formed on a large scale. The water in these compartments may not be suitable for any use and the surface area could become dangerous due to sinkhole formation. 20

If dewatering is carried out for a sufficient length of time, the water table will be lowered to such an extent that the pressure will only be sufficient to force a quantity of water equal to the normal recharge into the workings. Equilibrium will thus be established and the pumping rate will remain fairly constant (Jordaan et al., 1960; Bredenkamp et al., 1991).

A profound change occurred in the Bank compartment on 26 October 1968. Mining by West-Driefontein Gold mine had extended to the Bank compartment across the dyke separating Bank and Oberholzer .compartments. In October 1968, inflow of enormous volumes of groundwater threatened the workings and the safety of the miners. (Fleischer, 1981).

On 13 December 1968 East Driefontein Gold Mine was given permission to de-water the Bank compartment. The water from the Bank compartment which flooded the West Driefontein mine void was removed and the Bank compartment which has been isolated by 2 seals, was de­ watered by East Driefontein Gold Mine.

The three eyes (Venterspost, Wonderfontein Eye and Dog van Wonderfontein) have all ceased to flow in 1949, 1959 and 1969 respectively. In 1969 Driefontein Gold Mine dug a canal in the bed of the Wonderfonteinspruit to drain the Bank compartment. During the mid­ 1970's DWAF authorised the Venterspost Gold Mine to construct an aqueduct over the Venterspost, Bank and Oberholzer compartments to prevent the re-watering of the compartments. This water was discharged in the Wonderfonteinspruit west of the Oberholzer dyke (Stoch, 2000).

After the underground flooding of the West Driefontein Gold Mine in 1968, it was decided to de-water the Bank compartment and the mines proceeded to pump large quantities of water to surface. This has caused the Wonderfonteinspruit to be completely dried out. Thetwo Eyes ceased to discharge any water. The sustenance of the area started occurring in 21

the mid 1940's in the Venterspost and in the mid 1950's in the Oberholzer compartments (Stoch, 2000).

The Venterspost dolomitic compartment is being de-watered by the Venterspost and Libanon divisions of Kloof Gold Mine. Bank compartment by Kloof Gold Mine and Driefontein Consolidated, and Oberholzer dolomitic compartments are also being dewatered by Driefontein .Consolidated Gold Mine and Blyvooruitzicht Gold Mine. The Gemsbokfontein compartment is partly de-watered by Randfontein Estates no. 4 shaft. The Zuurbekom compartment has since 1892 been exploited by Rand Water for urban water supply, as well as mining activities in the western section of the Gemsbokfontein compartment. It appears as if the water leaked from the Zuurbekom .compartment into the Gemsbokfontein compartment when the mine increased the rate of pumping (Foster, 1989).

The Boskop-Turffontein compartment in the west is virtually unaffected (in terms of volume) by mining activities and water from this compartment is mainly used for agricultural purposes.

Mining activities resulted in the interconnection of most of these compartments, i.e. the boundary dykes were breached at several places. Many of the mines are themselves also connected with one another even though different mining houses operate them. As a result, one particular mine on its own cannot be regarded as an isolated sink, which would fill with groundwater should mining cease. The neighboring, still operating mine, will be obliged to pump water from the defunct mine in order to be able to carry on operating (Van Wyk & Louw, 1993). Otherwise, the operational mine will be filled with excess groundwater, making it impossible to mine safely.

Blyvooruitzicht Gold Mine and Mponeng Gold Mine (AngloGold) are experiencing the interchange of water between compartments at present. When Blyvooruitzicht Gold Mine closes, the water will decant into 22

Mponeng Gold Mine. According to an agreement between Blyvooruitzicht Gold Mine, Driefontein Consolidated and Western Deep Levels, Mponeng Gold Mine may not pump this water into the Wonderfonteinspruit, but must pump it into the Loopspruit. This pumping of excess groundwater would effect the water quality in both these rivers.

Fleischer (1981) found that the lowest rate of the average annual natural recharge as a percentage of the rainfall, is found in Gemsbokfontein . compartment, namely 12,8% of the average annual rainfall. In the Zuurbekom compartment, the natural recharge is between 16,8 and 20,8%. Part of the recharge in the Zuurbekom compartment is due to inflow from the river.

The natural annual recharge at Venterspost compartment, after allowance is made for the inflow of groundwater from an adjacent compartment, constitutes 27% of the annual rainfall. A similar high rate of recharge has also been found in the Bank compartment, which constitutes to 24% of the annual rainfall (Campbell & Basson, 1986).

The high recharge rate observed in these two compartments is explained by specifically favourable percolation conditions prevailing along the Wonderfonteinspruit in the central sector of these compartments. In this area the Ecca shale cover has been mostly eroded, and sinkholes and dolines provide for swift intake of water. It is also presumed that with the dewatering of these compartments and the lowering of the water level in this central sector, an additional storage volume has been created in the aquifer, as compared to previous undisturbed conditions (Fleisher, 1981).

2.2.5 Different issues associated with the I-m pipeline

An unusual feature of the Kromdraai catchment is the existence of a pipeline (1 metre in diameter), that was constructed to facilitate gold

mining In the area. This pipeline carries the water of the 23

Wonderfonteinspruit from just below Donaldson Dam in the vicinity of Bekkersdal, to a point where it joins the Driefontein canal. The pipeline has a limited capacity and consequently the control of discharges into the Upper Wonderfonteinspruit upstream from the pipeline are of major importance to the management of this part of the catchment (Wates Meiring & Barnard, 1994).

Reasons for the L-m pipeline

Large parts of the Wonderfonteinspruit catchment are located on dolomitic formations. As a result, water in underground dolomitic compartments poses a problem to mining in the area, as the mines can become flooded. Large scale dewatering of the underground mine workings began in the late 1930's at Venterspost Gold Mine and still take place to allow continued access to the gold bearing ore. As a result of increased surface flow in the streambed originating from the dewatering process, sections of the Wonderfonteinspruit have become prone to sinkhole formation due to the resulting lowering of the water table.

Water recharge from the stream bed to the underground workings also poses a problem to mining activities. Prior to mining, water in the riverbed was limited to seepage from groundwater from springs (Eyes) or due to run-off after a severe thunderstorm. The natural process of sinkhole formation was therefore accelerated as a result of the artificial dewatering process. In order to avoid the dolomitic bedrock from filling up with water, a surface water conveyance system was constructed to carry water over the dolomitic compartments to limit the formation of sinkholes. The main features of this conveyance system is a pipeline, that conveys the water over the Gemsbokfontein, Venterspost, Bank and Oberholzer dolomitic compartments. The existence of the 1-m pipeline ensures that safe and economical mining can continue in this area. 24

Current and future problems associated with the l-m pipeline

Increases in upstream discharge from the users of the pipeline, as well as in urban development upstream of the pipeline, are expected to place an increasing demand on its capacity. Of importance to the future demand on the pipeline, are predictable increases in the discharges of treated effluent .from wastewater treatment works. The two waste water treatment works that impact on the flow in the pipeline are the Flip Human Waste Water Treatment Works, that currently discharges into the Upper Wonderfonteinspruit upstream of the pipeline, and the Hannes van Niekerk Waste Water Treatment Works that currently discharges directly into the pipeline (van Niekerk & Sutherland, 1994).

Growing discharges will put increasing demand on the 1-m pipeline which has a capacity of 114 Mljday. Silt and sediment collection in the pipeline may also have reduced the maximum flow capacity of this pipeline. Therefore it is predictable that the demand on the pipeline may with time exceed its capacity (Steward Scott, 1993).

2.3 Identification of Management Units

The Kromdraai catchment has a large surface area with different geographical features and different water uses. The whole Kromdraai catchment was divided into 5 smaller management units to define between different areas and to simplify the management of the catchment.

Management units are generally chosen according to local water use quality requirements, the locations of prominent pollution sources, natural river junctions, and existing infrastructure, such as dams and water quality monitoring points. It is also important to take cognisance of the boundaries between groundwater compartments (Smith, 1999). 25

These boundaries between de-watered and undisturbed compartments are of particular importance, since river water is lost to the former, while the latter tends to remain in a state of dynamic equilibrium.

By taking these factors into consideration it was proposed that the Kromdraai catchment be broken down into the following management units as indicated on the schematic map (Figure 2.2).

Upper Wonderfonteinspruit:

This management unit (1 on the map) includes the Wonderfonteinspruit from its origin in the Krugersdorp area up to the Donaldson Dam. The area is dominated by abandoned mine workings, unrehabilitated slimes dams, shafts, sand dumps an4 rock dumps. The Municipality of Krugersdorp treats industrial effluent from the Chamdor Industrial area at the Flip Human Waste Water Treatment Works. Currently there are no direct discharges into the Upper Wonderfonteinspruit by mines or other industries.

The Donaldson dam was selected as the end of the Upper Wonderfonteinspruit management unit, because it is situated on the Gemsbokfontein dyke and therefore it is isolated from the Lower Wonderfonteinspruit by the 1-m pipeline which discharges into the Turffontein Compartment about 40 km to the West. 26

N t

1. Upper Wonderfontein Manag m nt Unit 2 . Lower Wand rfont in Managem nt Unit 3. Upper Mooi River Management Unit 4 . Lower Mooi River an gement Unit 15. Loopsprult Management Unit

Figure 2.2. Schematic map of the management units for the Kromdraai catchment (Smith, 1999). 27

Lower Wonderfonteinspruit

This management unit (2 on the map) includes the Wonderfonteinspruit from the beginning of the l-m pipeline to Muiskraal at the confluence with the Mooi River.

The first 40km of the Lower Wonderfonteinspruit flows in the l-m pipeline. This pipeline transports water from the Donaldson dam over the .de-watered Venterspost, Bank, Oberholzer compartments, because of the presence of dolomites and the risk of formation of sinkholes in the river bed, and discharge it into the canal.

Upper and Lower Mooi River

These management units (3 and 4 on the map) includes the Mooi River from Bovenste Eye to the confluence with the Vaal River at Kromdraai.

The Mooi River is dominated by a nature conservation area, as well as by various farming activities. The Potchefstroom Municipality's waste water treatment works and some major industries are responsible for the main impacts on the water quality of the Mooi River, if the impact of the Wonderfonteinspruit is ignored.

Naschem is situated approximately 2km south of the Boskop dam further along the Mooi River. This ammunition manufacturing company has a diffuse pollution effect on the water quality of the Mooi River and surrounding areas. Dust from the process plant that is high in pollutants are blown all over the area and contaminates the surrounding soil and surface water. Final effluents from different sections of the process plants are treated and then discharged to evaporation ponds. The soil and underground water at these evaporation ponds are heavily polluted (Hamilton-Attwell, 1999). 28

Kynoch is a fertiliser manufacturing company in the Potchefstroom Industria area. Due to previous unsuccessful management of storm and wash water in the factory, high concentrations of phosphates entered the Wasgoedspruit, which is a tributary of the Mooi River.

Loopspruit

This management unit (5 on the map) includes the Loopspruit from its .origin in the Gatsrant up to the confluence with the Mooi River downstream of Potchefstroom.

Various mines discharges into the Loopspruit, namely Kloof Gold Mine, Anglogold Limited, Elandsrand Gold Mine and Deelkraal Gold Mine. Fochville is the only town situated in this area and its waste water treatment works discharges purified sewage water into the Loopspruit. The final purified effluent has high phosphate levels because the works are working at over capacity due to lack of funds to upgrade the works.

2.4 Conclusion

This chapter gave a general introduction to the natural catchment characteristics of the Kromdraai catchment. The geology of this area is quite unique with the existence of water filled dolomitic compartments. To be able to mine gold both safely and economically, the gold mines in the area must de-water these dolomitic compartments on an ongoing basis. The gold mines are pumping huge volumes of underground water to surface and then discharging it to the Wonderfonteinspruit. The formation of sinkholes in these de-watered areas necessitates the construction of a pipeline, l-m in diameter, to transport all excess water across these areas.

Due to the extended size of the Kromdraai catchment, the area was divided into 5 management units for more efficient management of this diverse catchment. Water quality data was collected from certain 29 monitoring points in all of these management units and this data was processed to determine the status of the surface water quality. In the next chapter, the quality status of the surface water is examined through the analysis of water quality data. 30

CHAPTER 3: QUALITY STATUS OF SURFACE WATER

3.1 Introduction

The water quality data collected in the Kromdraai catchment since 1979 and the subsequent analysis of this data are discussed in this chapter. . The water quality data collected are from the monthly monitoring programme done by the Department of Water Affairs and Forestry: Gauteng Office, as well as from the Directorate: Hydrology (Hydrology Information System) (HIS). An extract of the data used in this study is displayed in Appendix 1.

Water quality variables that will give a good indication of the quality status in the Kromdraai catchment, were identified as electrical conductivity (EC), total dissolved salts (TDS) and sulphate (S04). Due to the nature of this research, it was decided to concentrate mainly on electrical conductivity (EC) as a indicator of the water quality status in the Kromdraai catchment.

Electrical conductivity is the reciprocal of resistance in ohms between the opposite faces of a l-cm cube of an aqueous solution at a specified temperature. The units are mhos. Because these units are large, micromhos are generally used. The International Unit for conductivity is the siemens, which is numerically equivalent to the mhos. Conductivity is a good estimator of TDS because TDS in mg/I is proportional to the conductivity in micromhos (Hounslow, 1997).

Sulphate in solution is directly linked to the oxidation of pyrite. The gold bearing ores are rich in pyrites and sulphate oxidation fs an indication of the impact of mining (Marsden, 1986). These constituents will give a clear indication of the general water quality status in the area and the extent of impact by the mining industry on the water quality. 31

3.2 Pollution sources in the Kromdraai catchment

Anthropogenic activities that impact on the water quality of the catchment include gold mining, industries, agriculture, waste water treatment works and local towns with informal and formal developments.

Pollution impacts are generally divided into point and diffuse sources. Usually the volume and pollutant concentration of a point source is easily quantified. This includes industrial and municipal effluent discharges and discharges from mines. Diffuse source discharges are difficult to quantify and are usually the result of run-off or seepage from agricultural and urban areas, as well as drainage and leaching from mines and waste disposal sites. Contribution to pollution in the Kromdraai catchment include mine industrial waste water, effluent from the various waste water treatment works, as well as diffuse sources such as leaching, surface run­ off from informal settlements and irrigation run-off (CSIR, 1991).

Due to the fact that gold mining is the main industrial activity in the Kromdraai catchment, the focus will be on mining as the largest contributor to pollution. The mines contribute both surface and groundwater, as most of the mines have to de-water their mining areas. Water pumped from underground includes water that flows into the mine from the dolomites, recycled water, as well as water obtained from Rand Water Board, used for cooling and refrigeration.

The groundwater in the catchment is impacted by surface and underground mining activities. Problematic issues associated with the mining activities are typically impacts from slimes dams, high salinity, heavy metals and radioactivity. Uranium, radium and thorium generally occurs in association with gold deposits along the West Rand. Ionizing radiation emitted from these radionuclides and their daughter products can be hazardous to human health (IWQS, 1996). 32

The potential for acid generation from sulphite rich slimes and waste rock dumps has long been recognised. The mined material is exposed to the environment and the natural processes of oxidation, biological activity, and by leaching by infiltrating water takes place. Natural leaching of the mineral content occurs. The process can be accelerated by a number of natural processes, including acid generation through bacteria. Such . leaching and flushing, with or without acid generation, can carry deleterious substances downstream into the receiving environments (IWQS, 1996).

Water pumped from underground by the mines in the Carletonville area and discharged to the natural environment, has at times a total dissolved solids (TDS) content of up to 600 mg/L This contamination occurs in the mine workings and in the vicinity of metallurgical plants and the leachate from slimes dams. Underground water pumped from mines is not potable and the TDS values generally are greater than 700 mg/I (Marsden, 1986).

Although there are in the excess of 45 water quality monitoring points in the Kromdraai catchment, it was decided to concentrate on the major 8 monitoring points due to the fact that they are placed at strategic points in the different management units (See Table 2). These 8 monitoring points will give a good indication on the water quality status in the Kromdraai catchment. This report therefore will concentrate only on these selected monitoring points in order to establish the effects that the gold mining industry has on the water quality of the environment. This impact will be established through the analysis of the water quality data from the 8 monitoring points. Photos of these points are depicted in Appendix 2. 33

Table 2. List of the major monitoring points in the Kromdraai catchment. :'t-=11' ::", ,- I·,,', Station HIS No. Site description and name of water body No. 1. C2H013 rrurffontein Eye 2. C2H025 Wonderfonteinspruit at the beginning of th e I-rn pipeline 3 . C2H080 Wonderfonteinspruit at the exit of th e I-rn pipeline 4. C2H063 West Driefontein canal at Rooipoort 5. C2Hl57 Wonderfonteinspruit on the low water brid ge to Abe Bailey 6. C2H060 Doomfontein Canal at Blaaubank 7. C2H069 Mooi River at Blaaubank. 8 . C2H085 Mooi River at Kromdraai before confluence with Vaal River

3.3 Analysis of the water quality data

All the water quality data for a certain time period was plotted in graphical format and analysed for trends. Seasons were also taken into account when the data was examined for trends. Trends and seasonality were examined in order to establish the water quality status of the Kromdraai ca tchment. The parameters used to determine the trends in the water quality were the relationship between the total dissolved solids (TD8) and sulphates (804) and between electrical conductivity (EC) and sulphates (804) .

The major monitoring points and the subsequent analysis of the water quality of these monitoring points were chosen as a result of the increase in pollution of the water resources from the pre-mining era to the current situation. The deterioration of water quality in the catchments will be clearly illustrated by means of different graphs.

Figure 3.1 illustrates the different monitoring points in relation to each other and to other major water features such as the l-m pipeline and Donaldson Dam. 34

Donaldson Dam T Beginning of L-m pipeline ~ C2H025 Exit of L-m pipeline C2H080

Driefontein Transfer Canal at Rooipoort C2H063

Abe Baily ..... C2H157

Wonderfonteinspruit

Doornfontein Canal C2H060

Mooi River at Blaaubank ..... C2H069

Turffontein Eye C2H013

Mooi River at Kromdraai C2H085

Vaal River

Figure 3.1: A line diagram indicating the specific monitoring points in the Kromdraai Catchment which are discussed in this research. 35

3.3.1 Turffontein Eye (C2H013)

The Turffontein Eye is a major source of water for the Boskop Dam and Potchefstroom Dam, the drinking water resources of Potchefstroom: This clear deterioration in the water quality of the Potchefstroom drinking water resource was one of the major driving forces for this research.

The EC value of the Turffontein Eye in the pre-mining era was 41 mS/m and the total dissolved solids (TDS) value was 264 mg/I (Kent, 1958). The current EC value is 115 mS/m and the TDS value is nearly 800 mg/I. This huge increase in pollutant concentrations over the past 42 years is of great concern and are thus the focus of the deterioration of water quality in the catchment. The Turffontein Eye is a dolomitic Eye which flows at 220 1/ s into the Wonderfonteinspruit, upstream of Boskop Dam. Boskop Dam is the raw water supply for the drinking water for Potchefstroom.

A polynomial trendline was used to illustrate any trends in the data over the time period. Figure 3.2 illustrates the relationship between the TD8 and S04 concentrations at the Turffontein Eye. The direct relationship between TDS and 804 concentrations is clearly illustrated. The polynomial trend gives a smoothed average over the time period. All the major spikes in the graph where the concentration suddenly drops or suddenly raises were smoothed out to give the polynomial trend. The two trends ran almost in parallel over the time frame, indicating the direct relationship between the TDS and S04 concentrations. ~ ~- Concentration (mg/l) tD ... Ii) to.) ~ 01 OD 0 tJ 0 0 0 0 0 0 0 0 0 0 0 ~ 1979-05-03 rn ~ - "~ 1979-10-18 ~I 1980-01-03 "" ~ I 1980-03-20 ~I 1980-07-17 0 a. I 1980-09-25 tD -l:S I 1980 -12- 18 l!J ': I 1981-03-05 3:: " I I -. 1 I I I ~ 0 1982-01-04 i fI) [ 1982-06-28 . . \L I JL.. I I -=en [ 1983-04-04 i rT"""'" I I t I I fI)

1984-04-02 0 1 ~ ~ 198 6-03-03 . . I -ra l I I s» ~ ! 198 6-12-0 1 ~ I'z \ 1 ~ I 1 I ~ ~ 04 s:: 1987-11- 1 "1 "'4t n 1988-06-13 ~ I I ~ I "'4t I 0 1989-05-10 :$ I ~ I II :.P" I I =~ ~ 1989-12-19 * I c:: I I 1-'::::: I I .... ~ 199 0 -09- 25 1 r..L 1 I ...... I I = l.!J 199 1-09- 05 1 ~ I-L ~ 1993-08-04 lJl

1994-08-26 1996-01-03 1 I J I I J$ 1997-01-15 ~ I ~ ~ ~ ~ I I •• ~ ·IHJ)~II 199 7-03 -18 0 0 0 0 :t ~~~rn 19 9 7-05- 28 f: 1 1- 1 I J. 11 rn~ii °01lll1lQ 1997-08-06 1 I Ll I 14...... I I ~ rn """' - -a---...... 1998-03-04 ~ II ::~ 0) 199 9-0 1- 14 :: 1.1 I I J 0\ I 19 9 9- 11-03 :.. EC VS 80 4 at Turffontein Eye 6001 804 (mgtl) If------140 --EC (mS/m) 5001 - P o l y . S04 (mg/I) 120 ...... - --P o l y . EC (mS/m) -bI) 100 a 400 -c= o ... - 80 i .fJ ...... e UJ .fJ 300 s= a Go> - U 60 o c= f;E1 o u 200 ~ -- 40 o UJ 100 20

1 1 . 0 t " I 11111::"1111 1111 1 '. :1:: :: '::.It::l: ": ,::: ::111 11 : ::. 0 ~~~~~~~#~~~~~~~#o/~~~~ ~ ~ ~ « ~ ~ ~ ~ ~ « ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~~~~~~~~~~~~~~~~~~~~~ 0,1'\. . 0,1'\. 0,'6 0,'6 0,'6 o,'b o,'b o,'b Oj~ 0,'6 o,'b 0,'0 o,qj o,OJ Ojo, o,OJ o,Oj Ojo, Ojo, 0,0, OjOJ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ Date

Figure 3.3: EC va 804 at Turffontein Eye

37 38

In Figure 3.3 the EC values and the 804 concentration at the Turffontein Eye are plotted from 1979 until 2000. The visual correlation between the EC values and the S04 concentrations are again clearly illustrated in this figure by the polynomials. When the EC value rises, the S04 value rises in direct relation. Jordaan et al., (1960) indicated that sulphates are one of the major pollutants in the gold mining industry due to the oxidation of . pyrites in the water.

Due to the nature of this research and to simplify the graphs, all the other graphs will only concentrate on EC values over a certain time period to reflect the pollution in each of the monitoring points, because the EC values gives a good indication of water pollution or the deterioration In water quality of a water body.

The electrical conductivity at the Turffontein Eye will now be discussed to illustrate the deterioration in the water quality over the past 20 years. The 1979 to 2000 time series was divided into three sub-series to get a better impression of the deterioration of the water quality at Turffontein Eye. The EC values were plotted for 1979-1988, 1989-1996 and 1997-2000 intervals (Figures 3.4,3.6 and 3.7).

The EC value at Turffontein Eye from 1979 to 1988 is illustrated in Figure 3.4. From 1979 to the end of 1982, the EC value stayed constant at approximately 80 mS/ m. Since the beginning of 1983 the EC value steadily increased and maximized at nearly 120 mS/m at the end of 1988. This increase in EC values can be directly linked to the initiation of the Doornfontein Gold Mine no. 3 slimes dam. There were a number of sinkholes in the area where the slimes dam was build. These sinkholes were filled with slime in order to stabilise this area and preventing any further development of sinkholes. (Doornfontein Gold Mining Company Limited, 1982). These sinkholes are a direct pathway between the slime and groundwater, thus contributing to groundwater pollution. 39

Wolmaran s (1978) indicated in a report to Gold Fields of South Africa Limited, that the sinkholes in that area do not pose a threat to the placing of new slimes dams in the area. Wolma ran s stated that the disposition of existing sinkholes could be ignored in siti ng the new slimes dam. Doornfontein Gold mine dumped 122 OOO-ton slime during February ,1982 on the no. 3 slimes dam (Doornfontein Gold Mining Company Limited, 1982). Any rain water that falls onto these slimes dams, percolates through the slime, getting polluted with the slime and ends up polluting the groundwater below and near to these slimes dams.

EC at Turffontein Eye 1979 to 1988 - EC (mS/ m ) - Poly. EC (mS/m) 140 120 ~ ~- ~ .. ~ 100 ~ .....i l'I.l 80 tI\ ~ ! ~ ... .. - , ~ 60 40

20

o '" " " ~¥~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~ .~ '~ '\ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ Date

Figure 3.4: EC at Turffontein Eye: 1979-1988

If the slimes dams are not properly rehabilitated with grass or cladded with rocks, rain water can erode and wash some of the slime s material away into the environment. This can lead to the further pollu tion of surface water bodies and ground water in the vicinity of the slimes dams. According to traditional thinking, the way to prevent the pollution of groundwater nearby slimes dams, is to seal or cap these dams to prevent any water to percolate through the dam. However, solutions may be found 40

in innovative ideas where the slimes dams are dealt within a case by case manner within a regional strategy.

A study was conducted by the National Mechanical Engineering Research , Institute in 1956 to determine if there is an underground link between Driefontein slimes dam and the Oberholzer Eye (Roux, 1956) . Th e study showed that after 40 tons of table salt was added to the mine wa ter, an increased concentration of chloride was detected at the Oberholzer Eye.

To illustrate more clearly the increase in EC values over time in the Turffontein Eye , two time series were plotted on a graph in Figure 3.5. The distinct difference in the EC values for the time series 1979 to 1982 and the time series from 1983 to 1989 is clearly illustrated in the figure. The time series from 1979 to 1982 is illustrated by the red line in Figure 3.5 which is consistently just below 80 rnS/m. This indicated that the water quality at this point was of constant good quality with little external pollution sources influencing the Turffontein Eye.

Time Series at TurfJontein Eye 1- 1979-1982 Time Series 140 - 1983-1989 Time Series ~ 120 ~ - 100 ---- -

...... a- 80 en .-- ! - s 60

40

20

0 Date

Figure 3.5: Time Series at Turffontein Eye 41

The blue line in Figure 3.5 indicates the time series from 1983 to 1989 and shows a definite rise in the EC value for that time period from the 1979 to 1982 time period. The average EC value for that time series is around 120 mS/m, indicating a serious external pollution source influencing the Turffontein Eye. This study also showed that there is a definite link between the water from underground sources in the different mines within the same compartment. The caverns in the dolomite above .the West Driefontein and Blyvooruitzicht Gold Mines are freely interconnected, so that the solution of the water problem for these two mines must be considered as a joint undertaking.

In Figure 3.6 the EC value at Turffontein Eye is illustrated from 1989 to 1996. The polynomial trend indicates a decrease in the EC value from 1989 to 1993, after which it increased again. The EC value decreased from 125 mSjm in 1989 to 95 mSjm in 1993. This decrease in the EC value is an indication of the improvement of the water quality at Turffontein Eye in that time period.

The spikes in the graph where the concentrations suddenly fall dramatically may be attributed to rainfall. In August 1993 there is a clear dip in the EC value and the average rainfall for 1993 was 10mm higher that in 1992 according to Figure 3.8. High volumes of rainwater falling.in the catchment close to the Turffontein Eye, can dilute the concentrations of the pollutants in the water, reflected by the dips in the graph.

High average rainfall were measured at Carletonville in 1990 and in 1992 (See Figure 3.8). This could be a contributing factor to the fluctuations in the EC values at Turffontein Eye from 1990 to 1992.

The improvement in water quality at the Turffontein .~ye can also be ascribed to the fact that Doornfontein Gold Mine stopped depositing slime during 1995. Although the effect of the non-deposition of slime on the

43

EC at Turffontein Eye: 1997-2000 I- EC , 140 I--- I- poly. EC (mS/m) 120 .-. -. - - .... A -. ".,.",...-..-. Alto. 100 .. ,,- "V' ~" 1l i ~ -- V· ...... 80 fIJ • ! 60 to) r:a::l 40

20

Figure 3.7: EC at Turffontein Eye: 1997-2000

Towards the end of 1999, the EC value further declines to around 80 mSj m. This indicates that the impact from the no. 3 slimes dam was being reversed. This EC value is nearly the same as it was in 1979, around 80 mSjm. Continued monitoring of the water quality at Turffontein Eye will ultimately indicate at what limit the improvement in quality will equilibrate.

The average rainfall measured at the Carletonville weather station IS illustrated in Figure 3.8. Data were obtained from the Department of Environmental Affairs and Tourism. (DEAT, 2001). According to this figure, there was an upward trend in the average rainfall from 1982-1998. The average rainfall differed considerably every year with the average highest rainfall in 1980, 1986, 1992, 1995-1998. 44

Average Rainfall in Carletonville l "'Average ~ I - Poly. (Average RainfaD) 80 .------,

7O HII.------iIF--~.__--_'II~

Gsa L~~~,L.~:::~~~~~2~L--~LLJ ! :; 40 t------'~~------___i ~ ~ 30 i------___i

20 -+------1

10

0 0 ... C'f l') ~ III ID e- 00 01 0 ... C'f l') ~ II) ID l'" 00 01 00 00 00 00 00 00 00 00 00 00 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 ...... 8C'f Year

Figure 3.8: Average Ra infall at the Carletonville Weather Station: 1980-2000.

The impact of rainfall on the water quality in Turffontein Eye IS much wider than just the rainfall in or near Carletonville. All rain water that fell in the whole catchment from Krugersdorp to Carletonville has an impact on the water quality at Turffontein Eye as well as on the Upper Wonderfonteinspruit, Lower Wonderfonteinspruit and on the Mooi River.

3.3.2 Wonderfonteinspruit at Gemsbokfontein (Beginning of the L-m Pipeline) C2H025

Monitoring station C2H025 was selected because of the importance of the 1-m pipeline in the de-watered dolomitic compartments of the area. The 1­ m pipe-line transports the Donaldson Dam overflow as well as all fissure water being discharged by Venterspost Gold Mine (an estimated 30 MIlday), over the de-watered dolomitic compartments. The Hannes van Niekerk waste water treatment plant also discharges 25 Ml/day into the pipeline. All water in the 1-m pipeline then gets discharged 22 km further downstream into the Driefontein Canal, just upstream of Harry's Dam. 45

It was therefore of vital importance to determine the water quality of the individual discharges into the 1-m pipeline, as well as the cumulative, effect of all the water that was and is also discharged into the Wonderfonteinspruit.

Figure 3.9 illustrates the EC values at the beginning of the 1-m pipeline from 1980 until 2000. The polynomial trend indicates that the EC values .increased significantly from 1980 to 1989 and thereafter decreased steadily until 2000. The Venterspost Gold mine was an active mine in the 1980's, but ceased production in 1994. The mine however, continues to pump ±30 MIJday into the 1-m pipeline to enable the neighbouring Libanon Gold Mine and Kloof Gold Mine to mine gold economically and safely. The quality of the water thatVenterspost Gold Mine discharged into the 1-m pipeline at the height of production, was much worse than the water quality presently being discharged.

The dips in the graph, where the EC value suddenly drops far below the average value, can once again be explained by rainfall. Storm water that falls in Kagiso, Bekkersdal and in other areas close to the Donaldson Dam does not all end up in the 1-m pipeline. These huge volumes of cleaner water will not only dilute the EC values of the water entering the 1-m pipeline, but spill over into the sinkholes in the Wonderfonteinspruit and end up in the Venterspost compartment. 46

EC at Beginning of the I-m Pipeline (Wonderfonteinspruit)

250 ~~~~~~~~~~~~~~~~-EC (mS/m) 200 - Poly. EC (mS/m) ...... i ena 150 100 ,...------. ----='-- ~ 500 '*-.._------.-- - ..-

~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~ ~~~~~~~ff~~~~~~ff~~~ ~~~~~~~~~~~~~~~~~~~~ Date

Figure 3.9: EC at the Beginning of the 1-m Pipeline (Wonderfonteinspruit) C2H025

3.3.3 Wonderfonteinspruit at the Exit of I-m Pipeline (C2H080)

Figure 3.10 illustrates the EC value of the Wonderfonteinspruit at the exit of the l-m pipeline. This monitoring point is also of great importance for the over all water management in the area, as it indicates the water quality of all the water being discharged into the l-rn pipeline. The EC value fluctuates over the time series. This can be due to the different discharges by the different mines and by the sewage works in the area. Rainfall plays an important role in the water quality at the exit of the l -rn pipeline as a significant volume of clean storm water also gets discharged into the pipeline, resulting in the dilution of the water.

The diluting effects of the purified sewage water can clearly been seen in Figure 3.10 as indicated by the green linear line. In the 1980's the EC value at the beginning of the l-rn pipeline (Figure 3.9) were around 200 mSj m and at the exit (Figure 3.10) after the -purified sewage water has been added, the EC values fell to between 100-120 mSjm. While purified sewage water may have a higher organic load than the discharged water from the gold mines, it has a much lower salt load (804) than mine water . 7

EX:: t EKitof I-m Pipeline (Wonderfonteinspruit)

.....i ! ~

20 1---

Figur 3 .10: EC at Exit of the I -m Pip line (Wonderfonteinapruit) C2H080

3.3.4 Driefontein Tran verse Canal at Rooipoort (C2H063)

Driefontein Con olidated Gold mine eontinu d to d -wa t r th Bank and Ob rholz r dolomitic compartments in ord r to eontinu mining. By d finition fissur water i wat r that ps or p reolat through th fi ur in th roek formations into th mm working. Thi fi ur wat r mu t b k pt P rat from th min urfac and from h pro w t r in ord r to pr v nt it from g ttin pollut d. Th fi ur w t r i pump d to urf e nd di eh rg d to th Wond rfont in pruit b for it t pollut d .

ri font in n olid t d old min di pproxim t ly 23 Mild Y n fi ur w r , whi h i pump d fr m th North h ft to th Wond r- f nt in pruit vi th r nsv r ea n I t R oip rt. Pollut d pr w t r 48

is pumped from the no. 4 shaft to the surface and gets discharged via a pipeline to the settling ponds (Woodhouse, 2000).

OCat Driefontein Transfer Canal (Rooipoort)

- EC(mS/ mJ .------1_ Poly. 1OC (mS/mJ

100 t------.-- .

...... i 80 t---- -a-- -.,- -tIoIr---- CIl ! 60 -l'-- ._- -a--r-- ~ 4Ot------_._- -­ 2O t------1 o ."",,, ,, , ," " '" ."",,, , ~~~~~~~~o/~~~~~~~~~~~~~~ ~~#~~~~~~#~~~~~~~~~~~$~ ~#~~~~~##~~#~~~~~~~~#~~ nLte

Figure 3.11: EC at Driefontein Transverse Canal Rooipoort (C2H063)

Figure 3.11 shows the EC values of the combined water where the fissure and process water are mixed and discharged to the Wonderfonteinspruit. From 1980 to 1995 the quality of this discharged water was reasonable (50-80 mSjm). The fissure water played a major role in diluting the more polluted process water. In 1990 the EC values rose to around 100 mSjrn and decreased again to 80 mSjm in 2000. These figures are within range that the water use permit from the Department of Water Affairs and Forestry requires from Driefontein Consolidated Gold mine. (DWAF, 1998b). 49

reat Abe Baily (Wonderfonteinspruit)

120

100

80 if (1J -! 60 ~ 40

20

O +--r-___r_--,--_r__....,....-~____r_-_r___r____r___,_-_r__..,..__,_____r_____,r___r_.....,____r____,-,_J

~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ Date

Figure 3.12: EC at Abe Bally (Wonderfonteinspruit) C2H175

3.3.5 Wonderfonteinspruit at Abe Baily (C2H175)

The EC value at Abe Baily C2H175 (Wonderfonteinspruit) is illustrated in Figure 3.12. Only da ta from 1997 to 2000 is available for this monitoring point. The monitoring point at Abe Baily is the point in the Wonderfonteinspruit where all discha rged water from Rooipoort and from the exit of the I-m pipeline flow together before it runs further downstream in to the Wonderfonteinspruit.

The waste water treatment works at Oberholzer, discharges up to 8 Ml purified sewage water per day, about 5km downstream into the Wonderfonteinspruit upstream of Abe Baily. These discharges can contribute to the dips in the EC values at Abe Baily, as they consist of rain water resulting in the dilution of the Wonderfonteinspruit's water. The average EC value for the discharge from the Oberholzer sewage works is 80 mS / m. The quality of th e purified sewage.water varies on a daily basis 50

because of problems with infrastructure at the treatment plant and with high loads with which the treatment works can not cope.

3.3.6 Doornfontein Canal at Blaaubank (C2H060)

Blyvooruitzicht and Anglogold gold mines discharge polluted process water from underground to the Wonderfonteinspruit via the Doomfontein canal. The quality of this discharged process water is bad with an average EC value of 200 mS/ m since 1979 to 1989, as clearly illustrated in Figure ·3.13.

There are a number of very high spikes in the graph where the EC value has risen to over 400 mS / m, even as high as 500 mS / m. This quality of water being discharged is totally unacceptable for any fresh water system. The EC values at Doomfontein canal from 1991 to 2000 are illustrated in Figure 3.14. Since 1990 to 1997 there was an improvement in the general water quality in the canal. The EC trend as indicated by the polynomial trend, was on average at 150 mS/ m for the time series.

The volumes that were discharged by the different mines would have been useful in explaining the graphs, but since some mines did not have accurate flow volumes, the volumes were not used. There is also a problem with some farmers that are illegally using huge volumes of this canal water for flood irrigation of crops. This also contributes to the inaccurate volumes being discharged down the Doomfontein canal. 5 1

OC at Doomfontein Ca1l8): 1979-1990

600 -~ ( mS/ m) 500 - Poly. ~(mS/m)

400 .....i C1J ! 300 ~ 200

100

O +---r----r----,.- .,....-...,....---,-----r- ,--...,....---,-----r----,,....--,---....,----r-----r- .,....-...,....---,----.-----r' cccccccccccccccccccccc ~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~

1)lte

Figure 3.13: EC at Doomfontein Canal: 1979-1989 (C2H060)

EC at Doornfontein Canal: 1991-2000

- EC (m S / m ) 350 ,------1 - Poly. EC (mS/m) 300 +------'------.-- --,' i 250 +------,-- 200 +r---4~------__;_____=_.____---__:__---- - ­u.l ! 150 ~ 100 +---'~---'...... ---- __"_'~ - 50 +------1

::: ' ,::':: ,:: ,::::::: '~:::"':::: ,,:: "' '' ,:: : .:::: ,:~:::: ,: ,~: ":: " ~, :', :: : :, :' :,, ~ " o "" m'" "'; ".",""""••"","", '" ;,,,, ,,' W wo, :, W " " :,, :: ::', :,, ::::..:: ::::: :" "",,:', :, : :. : '::::,:: :: ", :::' ":::': ,:: , , ;":' : ' :' , :" ~~~~~~~~~~~~~b~~~~~~~~~~~ ~~~~~~~~y~~~~~~yw~~~~~~w~ww~ ~o ~ -» ~~ (I/0 ('/0 (1/~ ~o ~ ~o ~~ ~O ~o ~o Pj{"'r rd rd"'r ((/0 !\$) p,f:'filO~"'r ~$$$~$$$$$~~~$$~~$~~~~ Date

Figure 3 .14: EC at Doomfontein Canal: 1991-2000 (C2H060) 52

3 .3.7 Mooi River at Blaaubank (C2H069)

Blaaubank is an important monitoring point for water quality, because it is the point where the ground water that is pumped from the compartments and surface water come together, and it gives an indication of the pollution contribution from all the mines and sewage works in the Upper and Lower Wonderfonteinspruit catchments. Due to high volume of data that is available for the Mooi River at Blaaubank, it was decided to divide the data into 2 time series. In Figure 3.15 the polynomial trend is indicated with the red line an d represents EC values from 1979 to 1989 . The EC value started at arou n d 100 mS/ m in 1979 and steadily increased to around 200 mS /m by 1986-1987.

This increase in the EC value over that time period can be attributed to the fact that most gold mines in the a rea were in full production due to the h igh gold price in the 1980's. Higher volumes of pollu ted water were thus d ischarged by the gold mines in the area.

EC at Blaaubank (Mooi River): 1979-1989 ,------11 - EC (m S/ m) 400 - Poly. EC (mS/m) 350 -f------I-- --;------I 300 4------+-- +------1 a 250 -f------.--.-.._-a:-..---L-----::+-- .._-.r------.J fI) ­! 200 +-~.----...... -­ ~ 150 100 500 -f------_ -I

O":J " "" O~"fJJ """~ ":J"'),,f)!,,') ~ ""tp O":J ":J"i!J 0'" otO ':\t" ~" r:!' ~ ~o PJ>rJ' -r ~> tVr' (c(~ -re: -r.ft.> rv~ «, ...; rJ'''' «. ~ if ~ 'Ii tV ~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ Date

Figure 3 .15: EC at Baaubank (Mooi River): 1979-1989 (C2H069) 53

The EC values at Blaaubank in the Mooi River from 1990 to 2000 are illustrated in Figure 3.17. In the early 1990's the average EC value has decreased to around 150 mS/ m, and from 1994 it decreased even further to 110 -120 mS/m.

EC at Blaaubank (Mooi River) 1990-2000 ,------, - E C(m S / m ) 250 .,------j- Poly . (EC(mS/m))

200 -j------.------j i ..... 150 C1.l

! 100 -t-=-- --'--'-.....J-- --=------H-1R-4-__~~ ~ 50 -j------j

O +----.----,- .,-----,------,-- .,----,------,-- ,-----,------,--.,----,---,------,r--,.------,-----,- ,------.-----'

~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ Date

Figure 3.16: EC at Blaaubank (Mooi River): 1990-2000 (C2H069)

3.3.8 Mooi River at Kromdraai (C2H085)

The last monitoring point that will be discussed is the Mooi River at Kromdraai. This is the point where the Mooi River enters the Vaal River and thus demarcates the Upper Vaal water management area. This point in the Mooi River will give some indication on the pollution load being added to the Vaal River. All impacts from the Upper Wonderfonteinspruit, Lower Wonderfonteinspruit, Loopspruit and the Mooi River with all the various tributaries, flow into the Vaal River at this point. 54

EC at Kromdraai (Mooi River): 1986-1996

140 ..- --I- EC (mS/m) - Poly. EC (mS/m) 120 4------"======!..J i 100 4------.------,,--, {/.) 80 --=-- ....,. ­a - 60 ~ 40 200 -t-"'------"------_.--"------l....

~ ~ ~ ~ ~ q ~ 0 ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ b ~ ~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ Date

Figure 3.17: EC at Kromdraai (Mooi River) 1986-1996 (C2H085)

Th e polynomial curve in Figure 3.17 indicates the average EC values at Kromdraai from 1986 to 1996. There is a considerable fluctuation in the EC values from 1986 to 1989, after which it started a steady increase. The fluctuations can be explained by the impact of rainfall in the various sub catchments, because this point is the lowest point in the Kromdraai catchment. All the discharges from the mining industry in the Wonderfonteinspruit and Loopspruit catchments, as well as all purified sewage water being discharged by the local authorities, will eventually flow past Kromdraai. The average EC value for the time period from 1986 to 1995 was 70 mSjm. In 1995 the average EC value increased to 90 rnSjm. The EC value started at nearly 100 mSjm in 1996 and went steadily down towards 1997. In Figure 3.18, the average EC value from 1997 to 2000 is around 75 mSjm. This is much lower than the EC value at Blaaubank for the same time period in Figure 3.16 (110 mSjm).

The lower EC value in the Mooi River at Kromdraai can be contributed to the fact that the water quality at the Bovenste Dog is of a very good quality since no mining activities take place near the Bovenste Dog. This water feeds into the Boskop Da m which is also of a better quality than that of 56 concentrations of pyrites and these pyrites are oxidised by water. This produces sulphuric acid resulting in acid mine drainage with a pH, of 2­ 4.5. The water in the mines then contains high concentrations of sulphates. The main impacts from the gold mining industry on water quality in this catchment is from this sulphate rich water that gets discharged into the environment.

.The direct relationship between the EC value and the sulphate concentration is clearly illustrated in Figure 3.3. It was decided for the purpose of this research to concentrate mainly on the EC value of a particular water sample as an indication of pollution.

The change in electrical conductivity (EC) value of 41 mS/m measured at the Turffontein Eye in the pre-mining era and the subsequent much higher value of 115 mS/m measured in 1989 at the Turffontein eye, indicate the major impact that the gold mining industry has on the environment. The total dissolved salts (TDS) concentration also went up from 241 mg/I in 1945 to nearly 800 tag]I in 1989.

The impact of the gold mining industry on the Turffontein Eye is clearly illustrated in Figure 3.5 where the EC values in two different time periods were compared. The EC value of the Turffontein Eye remained very constant from 1979-1982 before the Doornfontein Gold Mine started depositing huge volumes of slimes on its no. 3 slimes dam. The second time series from 1983-1989 indicates that the EC value increased from just below 80mS/ m to around 120 mS / m. This was the time when Doornfontein was at the height of its gold production. When Doornfontein gold mine stopped depositing huge volumes slime on the no. 3 slimes dam, the EC value started to decrease to around 100 mS / m and continued to show a downward trend. 57

Most of the other monitoring stations indicated an increase in the EC values in the time period 1980-1990, when gold mining was at its height on the Far West Rand.

The EC value of the Doornfontein Canal is illustrated in Figure 3.13 which indicates highly polluted process water being discharged to the Wonderfonteinspruit. The polynomial trend in the graph shows an EC value of around 200 mS/ m. This polluted water is being discharged into the Wonderfonteinspruit at Blaaubank, resulting in the pollution of the Wonderfonteinspruit.

The EC value of the Wonderfonteinspruit at Abe Baily (C2H175) is 90­ 100 mS/m that is upstream of Blaaubank (See figure 3.13). The EC value of the Wonderfonteinspruit at Blaaubank, just after the discharged process water from Doornfontein; raises from 100 mS/m to around 200 mS/m for the same time period (See figure 3.15).

The quality status of the surface water in the Kromdraai catchment is clearly shown to be negatively impacted upon by the gold mining industry. 58

CHAPTER 4 CONCLUSIONS AND RECOMMENDATIONS

4.1 Conclusions

The impact that the gold mining industry had on the water quality of the Kromdraai catchment was determined in this research. The Kromdraai catchment was sub-divided into 5 smaller management units. Various key monitoring stations that are strategically placed were used to collect huge volumes water quality data. This data was plotted on graphs and polynomial trends were drawn to determine the deterioration in water quality over a time period.

Sulphate pollution is a very serious problem in the Far West Rand due to the oxidation of pyrite in the gold, bearing rocks. This sulphate pollution has two main pathways to the water resources, through ground water and through surface water. The pollution from slimes dams is a long term impact that has two pathways. The ground water gets polluted through the percolation of water through the slimes dams and the surface water resources get polluted through dust from slimes dams.

Marsden (1986) found that pyrite oxidation in slimes dams is confined to a surface layer of about 2m in depth. This means that the rate of sulphate leaching is confined to the first year or two, when after the rate of pollution from slimes dams are much lower.

A previous study on the water quality of the Kromdraai catchment by Pulles Howard & de Lange (1999) indicated that the gold mining industry in the Far west Rand had and has still a major impact on the water quality of the Kromdraai catchment.

Although a number of different parameters can be used to evaluate a water sample, this research concentrated on electrical conductivity (EC) as 59

an indicator of pollution. The EC method is a quick reliable method that is not expensive and it gives a very good indication of pollution in water samples. Where samples show high EC values, a full analysis must be conducted to determine the major causes of the pollutant.

The EC values at all the monitoring stations indicate that the water quality has been deteriorating in the time period of this research. This deterioration in the water quality can not be totally blamed on the gold mining industry, but it can be stated, that the major cause of pollution in the Kromdraai catchment, is due to the mining of gold. To get a complete picture of the status of the water quality in this catchment, a full spectrum analysis must be done to determine what other contributing factors are causing the deteriorating of the water quality in the Kromdraai catchment.

One of the objectives of the Water Act (Act 36 of 1998) is to protect the water resources for sustainable use by present and future generations. Integrated environmental management of which integrated water management forms a critical part, can achieve this. In order to be successful in this integrated approach to environmental management, reliable data is of vital importance.

4.2 Recommendations

This research showed that there has been deterioration in the water quality in the Kromdraai catchment since gold mining commenced in the early part of the previous century. Mankind, because of the higher demand on natural resources, will continuously impact upon the environment as a whole. These impacts can only be mitigated through integrated environmental management when all people in a particular catchment or area has a say in the management of their environment. 60

The National Water Act (Act No 36 of 1998) recognises "the need for the integrated management of all aspects of water resources and, where appropriate, the delegation of management functions to a regional or catchment level so as to enable everyone to participate."

This poses a challenge for the establishment, sustaining and co-ordination of institutions and structures to facilitate stakeholder participation in water resources management (WRM) .

. The National Water Act (Act No 36 of 1998) provides for the establishment of a number of statutory water management institutions (WMIs) to facilitate local participation. These institutions must give effect to the principles outlined in Section 2 of the Act and Policy, and in particular must ensure that they have "appropriate community, racial and gender representation". The establishment and operation of catchment management agencies (CMA), in particular, requires an extensive process of stakeholder consultation and public involvement to ensure local participation in water resources management and in the development of a catchment management strategy.

Catchment forums have been and are being used extensively by DWAF to involve stakeholders in decisions about water resources management. These forums have now become important bodies representing stakeholders in the establishment of CMA's, and are envisaged to play an active role in assisting these CMA's after their establishment. Catchment forums are particularly important in the development of the CMS, to address local priority WRM issues, but also provide a vehicle to facilitate the co-ordination and/or integration of WRM with spatial planning and land use management.

With the introduction of integrated water resources management (IWRM), the National Water Act (Act 36 of 1998) requires a paradigm shift in the way water resources are managed. In particular, this requires: 61

• Equity, sustainability and optimal use in the protection, development , and utilisation of water resources, as well as the institutions that are established for water resources management. • Decentralisation of decision making through the establishment of catchment based institutions (particularly CMAs) , based on a participatory approach to water resources management through the involvement of stakeholders.

Catchment forums provide the most suitable body to facilitate stakeholder participation in the formulation of this vision, determination of the RDM and the development of a catchment management strategy (CMS), thereby creating buy-in with the strategies to be implemented. CMA's should therefore make every effort (and may even have an obligation) to drive and/or support the creation and maintenance of catchment forums, in order to give effect to the purpose of the National Water Act in terms of public participation. In fact, catchment forums should be seen as an integral component of the institutional environment of a catchment management authority.

This highlights the policy requirement for DWAF and CMA's to ensure participation in WRM. Participation processes can be extremely resource intensive when done on an ad hoc basis, as well as posing problems around ensuring adequate capacity to participate and managing conflict between stakeholders with different interests. Catchment forums provide a potentially efficient and effective way to facilitate the coherent participation of stakeholders with diverse interests.

As· one of its initial functions, a CMA must develop a (CMS), in consultation with stakeholders within the water management area (WMA). This involves the identification of the WRM needs and formulation of an appropriate vision for the WMA, as well as the local sub-catchments within the WMA. Catchment forums also provide a vehicle for 62

stakeholders to contribute to the process of determining resource directed measures (RDM) to reflect the vision for the relevant water resource, including the water resources class and ecological reserve.

The gold mining industry in the Kromdraai catchment is a given and will not dissapear over night. The only effective way to manage impacts on the . environment is through integrated environmental management. Everybody who has the protection of the natural resources in these catchments at heart, must be actively involved in catchment forums.

Although the impacts from slimes dams on the environment IS not as severe as from sulphate rich mine process water, slimes dams must still be managed to prevent further pollution of ground - and surface water.

Some of the fresh material in the slime deposits currently being built up will become oxidized and will pollute the process water in contact with it. It is recommended that retaining dams must be erected around these sites to collect rain water and seepage water, and to prevent the escape of this polluted flow.

Freshly exposed pyrite oxidizes rapidly and oxidation extends to between 2 and 3 m from the surface in slime deposits. It follows that the erosion of . old surfaces, as well as the exposure of fresh material in other ways, should be avoided. The construction of berms and dams to prevent run­ off, and grassing of residue deposits to stabilize their surfaces, will help to prevent further pollution (Marsden, 1986).

The sharing of data is of critical importance for effective integrated environmental management. As most of the gold mines in the area are interconnected underground, neighbouring miries will have a direct impact on each other with regard to the pumping and discharging of water found underground. If all data and previous studies are available for all interested and affected parties, informed management decisions can be 63 made for the beneficial environmental management in the Kromdraai catchment.

In order to protect our national water resources, we need to have all data available to manage the impact from any pollution source.

The l-rn pipeline IS of critical importance in the Upper Wonderfonteinspruit. Information regarding the amount of water entering and leaving the l-rn pipeline is incomplete. Flow points must be re­ commissioned at the overflow of the Donaldson dam, beginning of the I-m pipeline and at the exit of the l-m pipeline. An accurate prediction on the increase of discharges from sewage works, mines and urban areas must be done to manage the future capacity of the l-m pipeline in order to sustain the policy of de-watering as long as mining takes place. When mining ceases, the surplus water will obviously be used to re-water the dolomitic compartments.

Pollution of ground water from slimes dams is a well-known fact, but unfortunately these slimes dams are a given which can not be removed over night. A recommendation to minimise pollution into the ground water from the slimes dams, would be to seal the surface of the slimes dams to prevent any rain water from percolating through the slimes dam and becoming polluted. Rain water needs to be running off the slimes dam as fast as possible and not be allowed to accumulate on top of them.

Dust from the slimes dam poses not only a threat to the water resources, but also to human health. A possible way to minimise or mitigate the effect from slimes dams is to grass the dams.

The most important water users in the Kromdraai catchment are agriculture and domestic users. The demand on the water resources will increase as the population grows, emerging farmers get more empowered and future developments start to blossom. 64

REFERENCES

Acocks, J.P.H. 1988: Veld Types of South Africa. Memoirs of the Botanical survey of South Africa. No. 57. 3rd edition.

Asmal, K. 1998: In a speech to National Assembly on the second reading of the National Water Act. Parliament, Cape Town.

Bredenkamp, D.8., van der Westhuizen, C., Wiegmans F.E. and Kuhn C.M. 1986: Ground-water supply of Dolomite compartments west of Krugersdorp. Technical Report GH 3440. Department of Water Affairs and Forestry, Pretoria.

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APPENDIX 1 The data displayed in Appendix 1 is an extract of the data used for this research. The future name describes the sampling point with a reference number, the sample date and the variable concentrations.

Feature Name Date TD8 804 EC 1 C2H013QOl TURFFONTEIN EYE 1979-05-03 87.00 83.3 C2H013QOl TURFFONTEIN EYE 1979-05-10 573.00 152.90 74.2 C2H013QOl TURFFONTEIN EYE 1979-05-17 479.00 150.40 69.7 C2H013QOl TURFFONTEIN EYE 1979-05-24 562.00 150.00 77 C2H013QOl TURFFONTEIN EYE 1979-05-31 584.00 156.80 76.9 C2H013QOl TURFFONTEIN EYE 1979-06-07 571.00 144.40 75.4 C2H013QOl TURFFONTEIN EYE 1979-06-15 572.00 149.50 75.3 C2H013QOl TURFFONTEIN EYE 1979-06-21 567.00 150.20 78.2 C2H013QOl TURFFONTEIN EYE 1979-06-28 569.00 150.20 75.7 C2H013QOl TURFFONTEIN EYE 1979-10-04 574.00 150.10 75.3 C2H013QOl TURFFONTEIN EYE 1979-10-18 500.00 146.70 74.8 C2H013QOl TURFFONTEIN EYE 1979-11-08 581.00 149.60 75.3 C2H013QOl TURFFONTEIN EYE 1979-11-15 577.00 147.30 75.4 C2H013QOl TURFFONTEIN EYE 1979-11-22 599.00 137.20 74.4 C2H013QOl TURFFONTEIN EYE 1979-11-29 557.00 141.40 76 C2H013QOl TURFFONTEIN EYE 1979-12-06 74.4 C2H013QOl TURFFONTEIN EYE 1980-01-10 595.00 136.30 75.1 C2H013QOl TURFFONTEIN EYE 1980-01-17 567.00 137.70 72 C2H013QOl TURFFONTEIN EYE 1980-01-24 561.00 140.60 71.4 C2H013QOl TURFFONTEIN EYE 1980-02-07 565.00 143.10 71.6 C2H013QOl TURFFONTEIN EYE 1980-02-14 563.00 142.50 71.5 C2H013QOl TURFFONTEIN EYE 1980-02-21 515.00 142.90 74.2 C2H013QOl TURFFONTEIN EYE 1980-02-28 515.00 145.90 74.8 C2H013QOl TURFFONTEIN EYE 1980-03-06 489.00 137.50 75.4 C2H013QOl TURFFONTEIN EYE 1980-03-13 522.00 135.90 76.7 C2H013QOl TURFFONTEIN EYE 1980-03-20 530.00 139.20 76.4 C2H013QOl TURFFONTEIN EYE 1980-03-27 536.00 140.60 77.1 C2H013QOl TURFFONTEIN EYE 1980-04-03 541.00 141.40 76 ' C2H013QOl TURFFONTEIN EYE 1980-04-10 547.00 143.70 79.4 C2H013QOl TURFFONTEIN EYE 1980-04-17 532.00 141.30 78_ C2H013QOl TURFFONTEIN EYE 1980-04-24 529.00 139.20 78 C2H013QOl TURFFONTEIN EYE 1980-05-01 546.00 144.20 78.8 C2H013QOl TURFFONTEIN EYE 1980-05-08 537.00 144.50 77.6 C2H013QOl TURFFONTEIN EYE 1980-05-15 536.00 143.40 78.1 C2H013QOl TURFFONTEIN EYE 1980-07-10 535.00 143.40 74.2 C2H013QOl TURFFONTEIN EYE 1980-07-17 550.00 140.50 76 C2H013QOl TURFFONTEIN EYE 1980-07-24 559.00 144.30 76.2 C2H013QOl TURFFONTEIN EYE 1980-07-31 518.00 . 141.30 76.7 C2H013QOl TURFFONTEIN EYE 1980-08-07 512.00 142.80 78.2 C2H013QOl TURFFONTEIN EYE 1980-08-14 524.00 138.40 76.9 C2H013QOl TURFFONTEIN EYE 1980-08-21 528.00 143.50 76.5 C2H013QOl TURFFONTEIN EYE 1980-08-28 527.00 142.40 74.1 C2H013QOl TURFFONTEIN EYE 1980-09-04 528.00 141.50 74.5 C2H013QOl TURFFONTEIN EYE 1980-09-11 529.00 140.90 76.8 C2H013QOl TURFFONTEIN EYE 1980-09-18 553.00 156.00 72.8 71

C2H013QOl TURFFONTEIN EYE 1980-09-25 73.9 C2H013QOl TURFFONTEIN EYE 1980-10-01 73.3 C2H013QOl TURFFONTEIN EYE 1980-10-09 74.2 C2H013QOl TURFFONTEIN EYE 1980-10-16 70.9 C2H013QOl TURFFONTEIN EYE 1980-10-23 74.3 C2H013QOl TURFFONTEIN EYE 1980-10-30 74.3 C2H013QOl TURFFONTEIN EYE 1980-11-06 73.3 C2H013QOl TURFFONTEIN EYE 1980-11-14 74.4 C2H013QOl TURFFONTEIN EYE 1980-11-20 74 C2H013QOl TURFFONTEIN EYE 1980-11-27 74.8 C2H013QOl TURFFONTEIN EYE 1980-12-18 75.3 C2H013QOl TURFFONTEIN EYE 1981-01-01 73.3 C2H013QOl TURFFONTEIN EYE 1981-01-08 556.00 144.90 74 C2H013QOl TURFFONTEIN EYE 1981-01-15 557.00 148.20 74 C2H013QOl TURFFONTEIN EYE 1981-01-22 556.00 148.60 74 C2H013QOl TURFFONTEIN EYE 1981-01-29 554.00 139.20 73.3 C2H013QOl TURFFONTEIN EYE 1981-02-05 556.00 146.10 73.7 C2H013QOl TURFFONTEIN EYE 1981-02-12 552.00 147.50 74 C2H013QOl TURFFONTEIN EYE 1981-02-19 552.00 147.20 74 C2H013QOl TURFFONTEIN EYE 1981-02-26 559.00 145.10 75.5 C2H013QOl TURFFONTEIN EYE 1981-03-05 520.00 136.10 71.7 C2H013QOl TURFFONTEIN EYE 1981-04-02 566.00 152.40 75 C2H013QOl TURFFONTEIN EYE 1981-05-07 548.00 146.30 78 C2H013QOl TURFFONTEIN EYE 1981-06-04 544.00 144.20 77.2 C2H013QOl TURFFONTEIN EYE 1981-07-09 570.00 149.40 76 C2H013QOl TURFFONTEIN EYE 1981-08-06 541.00 147.50 80.1 C2H013QOl TURFFONTEIN EYE 1981-09-07 530.00 144.00 76 C2H013QOl TURFFONTEIN EYE 1981-11-02 534.00 143.30 78.4 C2H013QOl TURFFONTEIN EYE 1981-12-07 559.00 149.10 75.6 C2H013QOl TURFFONTEIN EYE 1981-12-10 533.00 151.60 74 C2H013QOl TURFFONTEIN EYE 1982-01-04 605.00 177.60 74 C2H013QOl TURFFONTEIN EYE 1982-02-01 570.00 147.10 74 C2H013QOl TURFFONTEIN EYE 1982-03-01 586.00 153.00 75 C2H013QOl TURFFONTEIN EYE 1982-03-13 564.00 145.00 76 C2H013QOl TURFFONTEIN EYE 1982-04-05 565.00 150.60 75 C2H013QOl TURFFONTEIN EYE 1982-04-15 514.00 157.30 72.9 C2H013QOl TURFFONTEIN EYE 1982-04-23 591.00 156.60 78.3 C2H013QOl TURFFONTEIN EYE 1982-05-03 589.00 153.10 78 C2H013QOl TURFFONTEIN EYE 1982-05-15 595.00 176.60 76 C2H013QOl TURFFONTEIN EYE 1982-06-21 78 C2H013QOl TURFFONTEIN EYE 1982-06-28 661.00 232.50 89.7 C2H013QOl TURFFONTEIN EYE 1982-07-17 707.00 269.20 94 C2H013QOl TURFFONTEIN EYE 1982-08-02 664.00 232.90 87 C2H013QOl TURFFONTEIN EYE 1982-08-10 668.00 251.30 93 C2H013QOl TURFFONTEIN EYE 1982-10-04 726.00 273.20 99.5 C2H013QOl TURFFONTEIN EYE 1982-11-19 728.00 268.20 98.7 C2H013QOl TURFFONTEIN EYE 1982-12-06 741.00 279.00 98.5 C2H013QOl TURFFONTEIN EYE 1983-01-03 84.9 C2H013QOl TURFFONTEIN EYE 1983-01-24 585.00 162.40 78.2 C2H013QOl TURFFONTEIN EYE 1983-02-28 594.00 159.60 79.7 72

APPENDIX 2

The photos displayed in Appendix 2 are of the different monitoring points described in this research.

Photo!: Wonderfonteinspruit at the Beginning of the 1-m Pipeline (C2H025) 73

Photo2: Wonderfonteinspruit at the Exit of the I-m Pipeline (C2H080) 74

Photo 3: West Driefontein Canal at Rooipoort(C2H063)

Photo 4: Mooi River at Blaaubank(C2H069) 75

. . Photo 5: Mooi River at Kromdraai (C2H085)

O:i1mEJ.i)~~~:.t' , • .•• Photo 6: Wonderfonteinspruit on the low water bridge to Abe Bally (C2H157) 76

Photo 7: Turffontein Eye (C2H013) 77

Photo 8: Doornfontein Canal at Blaaubank (C2H060)