FIRST ORDER ASSESSMENT OF THE QUANTITY AND QUALITY OF NON-POINT SOURCES OF POLLUTION ASSOCIATED WITH INDUSTRIAL, MINING AND POWER GENERATION
Report to the
Water Research Commission
by
RG Heath*, HD van Zyl**, CF Schutte***, JJ Schoeman***
* Golder Associates Africa (Pty) Ltd
** Tshwane University of Technology
*** University of Pretoria
WRC Report No. 1627/1/09
ISBN 978-1-77005-819-4
NOVEMBER 2009
Non- Point Source Pollution Assessment
DISCLAIMER
This report has been reviewed by the Water Research Commission (WRC) and approved for publication. Approval does not signify that the contents necessarily reflect the views and policies of the WRC, nor does mention of trade names or commercial products constitute endorsement or recommendation for use.
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EXECUTIVE SUMMARY
Internationally it has become recognised that Non-Point Sources of pollution (also known as diffuse source of pollution) plays a major role in the degradation of water quality, specifically with respect to salinity, eutrophication (nutrient enrichment), sediments, pathogens, pesticides (including persistent organic pollutants – POPs) and some heavy metals. It is now accepted that it is not feasible to properly manage water quality without addressing the contribution from non point sources. Consequently, attention is increasingly being devoted to the quantification of non point water source pollution and to identify means to control it cost-effectively at source.
In order to provide strategic direction to research initiatives and to ensure that all important potential Non- Point pollution sectors of the economy are receiving the required attention, the Water Research Commission initiated this study “To compile a first order inventory of the quantity and quality of water produced as non-point sources by the South African industrial, mining and power generation sectors, and assess the impact these have on the quality of the water resources”.
In-depth literature reviews on the mining industry, the industrial and power generation sectors were undertaken in an attempt to assist with the first order assessment of non point sources of pollution from these sectors in South Africa. The limited available information on non point pollution has been compiled into a consolidated overview that presents the current status of literature and available data for the industrial, mining and power generation sectors. Much of the information is available in reports and documents that have been prepared for different purposes. Although much is already known internationally about non-point pollution there is a dearth of available published, information in South Africa. The majority of the available information is only available in reports that have not been published or in a form that needs manipulation before relevant information can be derived.
In order to collect first order data for those sectors and sub-sectors for which insufficient data are available the following methods of data collection were used to gain information:
Presentations to Water Industry of Southern Africa (WISA) biannual conference and the International Water Association (IWA) annual conference
Survey questionnaire to the WISA Industrial Water Division
Presentations to selected industries, ESKOM and Chamber of Mines
Meetings with specific mining houses, ESKOM and industries
Meetings with the regulators Department of Water Affairs and Forestry (DWAF) and Department of Minerals and Energy
Water quality data downloaded from DWAF’s databases
In depth assessment of available data in reports
These meetings did not bring anything new to the table except that non-point pollution is recognised as a contributor to both surface and groundwater pollution.
In order to attempt to categorise the water qualities and quantities impacts associated with non-point sources data was synthesise to obtain an estimate of the threat that different mining, industrial and power sectors pose on the water resources.
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Some of the problems that limit the use of the available information and would necessitate further processing to normalise the data, derive from the fact that the investigations producing the information were done at different times to different levels of detail and using different approaches. A further complicating factor is that data for some sectors may not be available and may necessitate further investigation.
It must be pointed out that although there is a large amount of information available in the form of reports on special investigations conducted for individual industries, this data is not readily available because industries in general feel uncertain about how this type of information could affect their situation with regard to future applications for water use or wastewater discharge.
The overview of water use and waste production by different sectors needs to be interpreted for the effect sectors can be expected to have on receiving water quality. The mining industry is, for example, reportedly responsible for about 80% of the waste production (salts) and is furthermore, the source of acid mine drainage that is threatening the water quality of several important catchments in the country. However, other industries that produce much smaller quantities of waste may actually present an equal or even more serious threat to water quality in the catchments where they operate, especially if they have waste discard facilities that can be sources of non-point pollution after rain or wind events. It would thus be necessary to categorise waste types according to their effect on water quality and synthesise the data to obtain an estimate of the threat that different sectors and sub-sectors pose to receiving water quality.
Mining
South Africa is globally recognised as being a leading supplier of a variety of minerals and mineral products. Typical pollutants from the mines include sulphates, acidity, salinity and metals (including aluminium, iron and manganese) and may contribute to the three types of non point pollution caused by mining, i.e. surface water, groundwater and atmospheric pollution. Typical contaminants were identified which could potentially have an impact on non-point source pollution, e.g. metal concentration and a risk factor given to each. Typical sources of pollution were then identified, e.g. waste rock dumps, slimes dams, etc. A risk factor was given to each source type of pollution. The risks relate to the potential of the contaminant that originates from a specific source to pollute the surface, atmosphere or groundwater.
Gold and coal mining were identified as the mining commodities having the highest potential to contribute to non-point source pollution. This could mainly be attributed to the magnitude at which gold and coal are currently and was historically mined. Although the base metals have a wider range with regards to the type of contaminants produced, the scale of production lowers the risk of contributing to non-point source pollution.
Coal and gold mines, especially closed and abandoned mining operations, appear to be the most significant threats in terms of potential groundwater contamination from the mining sector in South Africa. Acid generation and decreasing groundwater pH has been noted in some gold and coal mining areas in South Africa, but in many cases, Acid Mine Drainage is neutralised by reaction with the country rock to produce saline drainage instead.
Unfortunately, due to the lack of detailed information, the following factors could not be incorporated into this risk assessment:
The differentiation between the impact of the different receptors (e.g. waste rock dumps) and between the different mining commodities.
The potential impacts of age of the receptors.
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The role of gas emissions from the different mining commodities.
The range (13 to 51%) of potential Non-Point source pollution contributions to salts balances at a catchment scale varied considerably from study to study, commodity mined and season. Despite the uncertainties in the accuracy of these studies the overall contribution of non point source pollution originating from the mining industry in South Africa is significant
Industries
The industry representatives were hesitant to give permission for the information to be presented in a WRC report. The reasons for this are obvious and understandable since the information is of such a nature that it could reflect negatively on the industries if it is used in a malevolent manner.
The collection of non point pollution data from industry has been difficult even though very good cooperation was given by most industry representatives. The overall impression is that the majority of larger industries are well aware of the potential problems associated with non point pollution and that in most cases measures have already been implemented or are being developed to combat this problem. The main ‘hot spots’ in terms of non point sources are the ‘historical’ sites where wastes had been disposed off over long periods of time into inadequately designed facilities and where adequate control was not exercised. These sites are very difficult and extremely costly to rehabilitate and the pollution effects have spread over large areas with contamination of groundwater the most serious problem. The extent of the pollution could not be quantified but from available information the pollution in some historic areas appears to be extensive.
The end result of all these factors is that the first-order assessment of non-point pollution by industry is only given in general terms. However, the nature of the assessment is such that it provides a good basis for follow-up studies on specific areas with the greatest potential for non point pollution from industries.
When considering the contribution of industries to non point pollution, a distinction must be made between industries within municipal boundaries and those in industrial complexes (whether a single industry or group of industries).
Industries within municipal boundaries fall under control of municipal bylaws and mostly discharge effluents to the municipal sewer. Control of storm water pollution from industrial sites is also controlled by municipal bylaws. Local authorities have responsibility for collection, drainage and disposal of urban storm water, including storm water from industries within their boundaries and must therefore control pollution of storm water by industries. However, there is a big concern about the capacity of local authorities to control storm water contamination by non point pollution from industries.
Most of the non point pollution emanating from industries in municipal areas would be very difficult to account for since it is actually ‘hidden’ in urban storm water. Non point pollution from these industries is mostly related to runoff resulting from rain events, making it even more difficult to quantify. There are however, also continuous sources of non point pollution that should be easier to identify and quantify such as streams leaving premises during dry spells. Possible causes of these include leakage from storage tanks, seepage from wet material, etc.
The priority industries suspected of causing the largest non point pollution have been included for South Africa and for some of the specific water management areas. The large industrial complexes such as Sasol, Iscor, Foskor, Sappi, refineries, AECI, Saldanha Steel were recognised as areas with high potential of non-point pollution. In most of these cases reports exist containing information on non point
v Non- Point Source Pollution Assessment pollution compiled for individual companies or the complexes as a whole. These are normally classified and not available without permission from the industry or consultant.
Almost all the industrial representatives were of the opinion that the contribution of non point pollution from current practices to overall pollution is much smaller than problems associated with treatment and disposal of effluents constituting point sources. The main concern over non point pollution relates to accumulated waste materials. Industries as well as DWAF are aware of these problem areas and studies and monitoring programs are underway in many instances to remediate these problems. Examples include monitoring of boreholes in the vicinity of waste disposal sites, studies on in situ remediation of ground water, soil remediation studies, etc.
The most serious non-point pollution problems that industries have to deal with are of an historic nature. This means that the older the site, the more and bigger the problems. Previous waste disposal or storage practices resulted in larger or smaller quantities of waste material on site, which may have caused soil contamination and ground water pollution. Many of these are in different stages of investigation or active remediation.
Power generation
South Africa’s generating technology is based largely on coal-fired power stations. Eight of the ten operational coal-fired power stations in South Africa are situated in Mpumalanga. The majority of the non point sources of impacts of the power generation industrial sector are as a result of atmospheric deposition. In order to gain a full understanding of the impact of non point source pollution associated with the power generating industry in South Africa further research should be conducted in order to establish independent references regarding the matter in a South African context.
Conclusions and Recommendations
The same general conclusions can be drawn from the mining, industrial and power generation sectors. These being:
There is a lack or readily available non point source pollution data in South Africa
There is a lack of willingness to share information
The current legislation does not enforce non point source pollution management of water resources
Many sectoral specific areas that require research investigation with regards to non-point sources quantification and prediction has been identified. The lack of sufficient, accessible and user-friendly information is perhaps one of the most significant obstacles to perform a proper environmental risk assessment. This includes industry not disclosing the full details of their emissions and waste disposal (and problems related to these), and Government Departments reporting information in a co-ordinated and integrated manner. Consequently this first order assessment indicates that there needs to be research into quantifying the real impacts of non point source pollution. The polluters as well as regulators need to be educated as to the potential impacts of this mainly unquantified source of pollution. Detailed catchment modelling would be required to refine the catchment specific contribution of non point source pollution originating from the mining, industrial and power generation sectors in South Africa.
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ACKNOWLEDGEMENTS
The research in this report emanated from a project funded by the Water Research Commission entitled: “A first order assessment of the quantity and quality of non-point sources of pollution associated with the industrial, mining and power generation”.
The Reference Group responsible for this project consisted of the following persons:
Mr M du Plessis : Water Research Commission (Chairman)
Mr N Lesufi : Chamber of Mines
Dr KJ Riedel : Sasol Technology (Pty) Ltd
Dr B Usher : Institute for Groundwater Studies, University of the Free State
Mr L Labuschagne : DME, Mineral Policy Branch
Mr N Bezuidenhout : Golder Associates Africa (Pty) Ltd
Ms J Pretorius : Institute for Groundwater Studies, University of the Free State
The financing of the project by the Water Research Commission and the contribution of the Reference Group members is gratefully acknowledged.
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TABLE OF CONTENTS
1 INTRODUCTION AND BACKGROUND ...... 1.1 1.1 Approach and Objectives of study ...... 1.2 2 LITERATURE REVIEW ...... 2.1 2.1 International trends ...... 2.1 2.2 South African Research Initiatives in Non-Point Sources Pollution ...... 2.4 3 METHODS AND STRATEGY FOR DATA COLLECTION ...... 3.1 3.1 The Mining Industry ...... 3.1 3.2 Industry ...... 3.3 3.3 Power Generation ...... 3.4 4 NON-POINT POLLUTION AND THE MINING SECTORS OF SOUTH AFRICA ...... 4.1 4.1 Introduction ...... 4.1 4.2 Main environmental regulatory tools currently available in South Africa to manage mining activities ...... 4.2 4.2.1 Constitution of the Republic of South Africa Act (Constitution) (Act 108 of 1996) ...... 4.2 4.2.2 National Environmental Management Act (NEMA) (Act 107 OF 1998) ...... 4.2 4.2.3 National Water Act (NWA) (Act 36 of 1998) ...... 4.3 4.2.4 Mineral and Petroleum Resources Development Act (MPRDA) (Act 28 of 2002) ...... 4.3 4.2.5 Rehabilitation of Derelict and/or Defunct Mines for which no owner exists or can be traced ...... 4.4 4.2.6 Mine Health and Safety Act (MHSA) (Act 29 of 1996) ...... 4.5 4.2.7 National Environmental Management Air Quality Act (2004) ....4.5 4.2.8 National Heritage Resources Act (NHRA) (Act 25 of 1999) ...... 4.5 4.2.9 Cooperative Governance ...... 4.5 4.2.10 Other forms of Regulatory Assistance ...... 4.5 4.3 Types of mining ...... 4.6 4.4 Overview of Non-Point pollution involved with the mining sector...... 4.7 4.4.1 Non-Point Pollution contributing to Surface and Groundwater Pollution ...... 4.7 4.4.2 Non-Point Pollution contribution to Air Pollution ...... 4.7 4.5 South African mining industry ...... 4.9 4.6 Classification of Non-Pollution Types Associates Mining Industry ...... 4.11 4.6.1 Risk analysis ...... 4.11 4.7 Quantification of Non-Point Pollution from SA mining Industry ...... 4.16 4.8 Waste Discharge Charge System (WDCS) ...... 4.24 4.9 Case studies of Potential Non-Point Mining Impacts ...... 4.26 4.9.1 Gold: Case Study 1: Vaal Barrage Catchment...... 4.27 4.9.2 Case Study 2: Lower Vet River Catchment ...... 4.32 4.9.3 Case Study 3: Koekemoerspruit (Middle Vaal) ...... 4.34 4.9.4 Case Study 4: Upper Olifants River (Loskop Dam) Catchment4.41
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4.9.5 Case Study 5: Platinum Industry ...... 4.44 4.10 Mining industry Non-Point Source Pollution contribution ...... 4.44 5 NON-POINT WATER POLLUTION: INDUSTRIES ...... 5.1 5.1 INTRODUCTION ...... 5.1 5.2 Methodologies ...... 5.1 5.3 Main environmental regulatory tools currently available in South Africa to manage industrial activities ...... 5.2 5.3.1 Constitution of the Republic of South Africa Act (Constitution) (Act 108 of 1996) ...... 5.2 5.3.2 National Environmental Management Act (NEMA) (Act 107 OF 1998) ...... 5.2 5.3.3 National Water Act (NWA) (Act 36 of 1998) ...... 5.3 5.3.4 Cooperative Governance ...... 5.3 5.3.5 Other forms of Regulatory Assistance ...... 5.3 5.4 Literature review and industry survey ...... 5.4 5.4.1 Introduction ...... 5.4 5.4.2 Industrial wastes ...... 5.5 5.4.3 Potential sources of Non-Point industrial pollution ...... 5.6 5.4.4 Industry categories based on type of waste / effect on water resources ...... 5.7 5.4.5 Priority industries with biggest potential for Non-Point pollution5.8 5.4.6 Literature on Non-Point pollution in specific industries ...... 5.10 5.4.7 Environmental issues associated with specific industrial sectors ...... 5.11 5.4.8 Identification and prioritisation of groundwater contaminants and sources in South Africa’s urban catchments ...... 5.11 5.5 Industry categorisation and risk factor assessment ...... 5.12 5.6 Discussion, evaluation and assessment ...... 5.28 5.6.1 Onsite storage of material and solid waste ...... 5.29 5.6.2 Onsite disposal of effluents ...... 5.30 5.6.3 Waste disposal sites ...... 5.31 5.6.4 Atmospheric emissions depositing on water surfaces or soil and contaminating runoff ...... 5.31 5.7 Conclusions ...... 5.31 5.8 Recommendations ...... 5.32 6 FIRST ORDER ASSESSMENT OF THE QUANTITY AND QUALITY OF NON-POINT SOURCES OF POLLUTION ASSOCIATED WITH THE POWER GENERATION SECTOR ...... 6.1 6.1 Introduction ...... 6.1 6.2 Scope of work ...... 6.1 6.3 Main Environmental Regulatory Bodies overseeing the energy sector in South Africa ...... 6.2 6.4 Overview of the power generating sector in South Africa ...... 6.2
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6.5 Electricity demand forecast ...... 6.7 6.6 Coal fired power generation ...... 6.8 6.6.1 Coal Mining and Preparation ...... 6.11 6.6.2 Coal Combustion ...... 6.16 6.6.3 Ash Disposal ...... 6.33 6.6.4 Overall Impact on Water Sources ...... 6.40 6.7 Nuclear power generation ...... 6.43 6.7.1 Nuclear power generation waste disposal ...... 6.44 6.7.2 Non-Point Source Pollution associated with Nuclear Power Generation ...... 6.46 6.8 Hydro electric power generation ...... 6.46 6.8.1 Non-Point Source Pollution associated with Hydro-Electric Power Generation ...... 6.47 6.9 Risk Assessment ...... 6.48 6.9.1 Environmental Areas ...... 6.48 6.9.2 Unit Activities ...... 6.49 6.9.3 Toxicity and Pollution Rating ...... 6.50 6.9.4 Risk Rating ...... 6.51 6.9.5 Overall Risk Factor ...... 6.52 6.10 Summary ...... 6.53 6.11 Conclusions and directions for future work ...... 6.54 7 GENERAL DISCUSSION AND RECOMMENDATIONS ...... 7.1 7.1 Mining ...... 7.2 7.2 Industries ...... 7.2 7.3 Power generation ...... 7.2 7.4 Recommendations ...... 7.3 7.4.1 Mining ...... 7.4 7.4.2 Industry ...... 7.4 7.4.3 Power generation ...... 7.4
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LIST OF APPENDICES
The following Appendices can be found on the enclosed CD:
Appendix A Gold Mining
Appendix B Coal Mining
Appendix C Platinum Group Metals (PGMS)
Appendix D Profile of the Diamond Industry
Appendix E The Iron and Steel Industry
Appendix F Titanium Mining
Appendix G Sand Mining and its Environmental Impacts
Appendix H Manganese Mining
Appendix I Radionuclides in the Mining Industry
Appendix J Organic Contaminants in Mines
Appendix K Base Metals selected in this study
Appendix L Chromium Mining
Appendix M Vanadium Mining
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LIST OF FIGURES
Figure 4.1: Total risk factor allocated to the different mining sectors ...... 4.24
Figure 4.2: Schematic showing approach to estimating NPS discharge to the surface water resource (Von der Heyden et al., 2005) ...... 4.25
Figure 4.3: The water balance between 1991 and 1992 in the Vaal Barrage catchment...... 4.29
Figure 4.4: Salt balance between 1991 and 1992 in the Vaal Barrage catchment ...... 4.29
Figure 4.5: Diagram to illustrate all the inflows and outflows of the catchment river system ...... 4.37
Figure 4.6: Water balance components to be considered for a complete water balance study ...... 4.38
Figure 4.7: Comparison of the contribution of Margaret Shaft to the flow at the C2H139 Weir in the Koekemoerspruit during the 2002 and 2003 winter months ...... 4.39
Figure 4.8: Comparison of the contribution of Margaret Shaft to the flow at the C2H139 Weir in the Koekemoerspruit during the 2001/2, 2002/3 and 2003/4 summer months ...... 4.39
Figure 4.9: Mean average volumes of underground water from DRD, volume of water directed to MWS, volume of water discharged from Margaret Shaft to the Koekemoerspruit and the volume of water measures at the C2H139 weir in the Koekemoerspruit...... 4.40
Figure 6.1: Energy sources used for generation of electricity in South Africa (MWE, as of 2000, Energy overview of South Africa, 2005) ...... 6.3
Figure 6.2: Percentage make up of Eskom Electricity Production (2003 Van der Riet M et al., 2004) .... 6.7
Figure 6.3: Long-term electricity demand forecast for South Africa (Giga Watts) ...... 6.8
Figure 6.4: Power Stations and their locations in South Africa ...... 6.9
Figure 6.5: Process for coal-fired power generation...... 6.10
Figure 6.6: Inputs and outputs of coal fired power generation ...... 6.10
Figure 6.7: Coal Production in South Africa in 2003 (Source: Minerals Bureau) ...... 6.11
Figure 6.8: Sectors of the South African coal market in 2003 ...... 6.12
Figure 6.9: Inputs and Outputs of Coal Mining and Preparation ...... 6.12
Figure 6.10: Inputs and outputs of Coal Combustion ...... 6.16
Figure 6.11: Percent Vapour Phase as a Function of Temperature for ...... 6.17
Figure 6.12: Categorization of trace elements based on volatility behaviour ...... 6.18
Figure 6.13: Conceptual Model of Atmospheric Deposition (Piketh and Annegarn,1994) ...... 6.20
Figure 6.14: Eskom ambient air quality monitoring network (Zunckel et al., 2004)...... 6.22
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Figure 6.15: Particulate (TSP), SO2 and NOx Emissions: ...... 6.23
Figure 6.16: Global Anthropogenic Emissions of Mercury (metric tonnes/year) ...... 6.24
Figure 6.17: Anthropogenic Emissions of Mercury : Distribution by Industrial Sector (Pacyna and Munthe, 2004) ...... 6.24
Figure 6.18: Indication of the relative position of monitoring sites Amersfoort, Louis Trichardt, Elandsfontein and Palmer (Zunckel et al., 2004)...... 6.25
Figure 6.19: Wet and dry atmospheric nitrogen deposition in Africa ...... 6.26
Figure 6.20: Sulphur emission rates in kton S/a for the Mpumalanga ...... 6.26
Figure 6.21: Wet and dry sulphur deposition in South Africa (Zunckel et al., 2002)...... 6.27
Figure 6.22: Proportional contribution of different sources to sulphur dioxidepollution in Mpumalanga (Whyte et al., 1995)...... 6.27
Figure 6.23: Sulphate concentrations for the Grootdraai Dam...... 6.28
Figure 6.24: Acid rain monitoring sites ...... 6.30
Figure 6.25: Ash Disposal ...... 6.33
Figure 6.26: Aqueous input and output streams: coal fired power generation ...... 6.34
Figure 6.27: Release of trace elements from South African fly ash when exposed...... 6.39
Figure 6.28: Water Management Areas in Mpumalanga ...... 6.41
Figure 6.29: Schematic diagram of the nuclear power generating process...... 6.44
Figure 6.30: Environmental pathways associated with discharge of treated Radiological Effluent into the sea ...... 6.46
Figure 6.31: Schematic diagram of the hydro-electric power generating process...... 6.47
Figure 6.32: Overall Risk Factors for various coal fired process configurations ...... 6.52
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LIST OF TABLES
Table 2.1: Classification of Non-Point source pollutants according to their sources and the impacts involved (Heath, 2001) ...... 2.3
Table 3.1: List of Companies / People consulted for Industrial Non-Point Source Information ...... 3.2
Table 4.1: Gold associated pollutants (Pulles et al., 1995; Pulles et al., 1996) ...... 4.10
Table 4.2: Risk factor associated with run of mill / ore milled ...... 4.11
Table 4.3: Apportionment of Non-Point Source Pollution in the mining industry ...... 4.12
Table 4.4: Typical contaminants risk factor associated with gold mining ...... 4.18
Table 4.5: Typical contaminant risk factor associated with coal mining ...... 4.19
Table 4.6: Typical contaminant risk factor associated with platinum mining ...... 4.20
Table 4.7: Typical contaminant risk factor associated with diamond mining ...... 4.21
Table 4.8: Typical contaminant risk factor associated with base metal mining ...... 4.22
Table 4.9: Run of mill / ore milled risk factor allocated to each mining commodity ...... 4.23
Table 4.10: Total risk factor associated with the different mining commodities ...... 4.23
Table 4.11: A summary of the water balance in the Vaal Barrage catchment (DWAF, 1995)...... 4.30
Table 4.12: Summary of the salt balance of the Vaal Barrage catchment (DWAF, 1995)...... 4.31
Table 4.13: Inflows and outflows listed for each calculation point in the water balance ...... 4.35
Table 4.14: Summary of Margaret Shaft influence regarding flow (ML/month) and TDS values (tons/month) for wet and dry periods ...... 4.41
Table 5.1: Classification and risk associated with Non-Point pollution from industry ...... 5.14
Table 6.1: South Africa's Licensed Power Stations (as of 2000) ...... 6.3
Table 6.2: Chemical Properties of Coal (Stuart et al., 1997) ...... 6.13
Table 6.3: Trace elements present in different types of South African Coal (Australian Coal Research Ltd., 1996 ; Wagner and Hlatshwayo, 2005) ...... 6.14
Table 6.4: Air pollutants emitted to the atmosphere during coal-fired power generation operations. .... 6.21
Table 6.5: Rainfall chemistry parameters ...... 6.29
Table 6.6: Volume-weighted mean chemical composition of precipitation and deposition at Amersfoort and Louis Trichardt during 1986-1999(Mpheya et al., 2004)...... 6.31
Table 6.7: Origin of acidity at Amersfoort and Louis Trichardt ...... 6.32
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Table 6.8: Relative contribution from different sources to the chemical composition of precipitation at Louis Trichardt and Amersfoort (Mpheya et al., 2004)...... 6.32
Table 6.9: Effluent resulting from dry ashing and wet ashing disposal systems (Hansen et al., 2002) . 6.35
Table 6.10: Trace metal composition of raw coal, fly ash and coarse ash (Scorgie and Thomas, 2006) ...... 6.36
Table 6.11: Chemical composition of fly ash produced at a power station in Mpumalanga (Surender and Petrik) ...... 6.37
Table 6.12: Characteristics of ash waters at a thermal power station in Mpumalanga ...... 6.39
Table 6.13: Important Isotopes resulting from nuclear power production ...... 6.44
Table 6.14: Elements Used to Compare Emissions from Hydro and Coal power ...... 6.44
Table 6.15: Unit Operations : Coal Fired Power Generation ...... 6.49
Table 6.16: Average Trace Element Removal Efficiency (%) for control devices ...... 6.49
Table 6.17: Functions used to evaluate Toxicity and Pollution Factor (TPF) ...... 6.50
Table 6.18: Toxicity and Pollution Factors (TPF) for various chemical compounds ...... 6.51
Table 6.19: Probability of occurrence ...... 6.52
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LIST OF ABBREVIATIONS
BOD Biological Oxygen Demand
BTEX Benzene, Toluene, Ethyl Benzene and Xylenes
DCE Dichloroethylene
DOC Dissolved Organic Carbon
HMX Cyclotetramethylenetetranitramine
MEK Methyl ethyl ketone
MTBE Methyl tert-Butyl Ether
PAHs Polycyclic Aromatic Hydrocarbons
PCBs Polychlorinated Biphenyls
PCE Perchloroethylene
PETN Pentaerythritol tetranitrate
RDX Cyclotrimethylene-nitramine
SS Suspended Solids
TCE Trichloroethylene
TDS Total Dissolved Solids
TPH Total Petroleum Hydrocarbons
VOCs Volatile Organic Compounds
1,3-DBN Dinitrobenzene
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LIST OF ACRONYMS
Bq Becquerel
CAPCO Chief Air Pollution control Officer
DACE Department of Adult and Continuing Education
DEAT Department of Environmental Affairs and forestry
DEBITS Deposition of Biogeochemically Important Trace Species
DME Department of Minerals and Energy
DTI Department of Trade and Industry
DWAF Department of Water Affairs and Forestry
EC Electrical Conductivity
ESP Electrostatic Precipitator
FGD Flue Gas Desulfurization
FPM Fine Particulate Matter
IDAF IGAC DEBITS Africa
IGAC International Global Atmospheric Chemistry
MWe Megawatts Electricity
MWh Megawatt-hour
NER National Electricity Regulator
NPS Non-Point Source
RGM Reactive Gaseous Mercury
SANAS South African National Accreditation Systems
TDS Total Dissolved Salts
TPF Toxicity and Pollution Factor
TSP Total suspended particles
UNFCCC United Nations Framework Convention on Climate Change
WMA Water Management Areas
ZLED Zero Liquid Effluent Discharge
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1 INTRODUCTION AND BACKGROUND
Internationally it has become recognised that Non-Point Sources of pollution (also known as diffuse sources of pollution) play a major role in the degradation of water quality, specifically with respect to salinity, eutrophication (nutrient enrichment), sediments, pathogens, pesticides (Persistent Organic Pollutants – POPs) and some heavy metals. It is now accepted that it is not feasible to properly manage water quality without addressing the contribution from Non-Point sources. Consequently, attention is increasingly being devoted to the quantification of Non-Point source pollution and to identify means to control it cost-effectively at source.
Non-Point pollution sources represent land use areas and activities that result in the mobilisation and discharge of pollution in any manner other than through a discrete or discernible conveyance (Pegram and Görgens, 2001). Non-Point Source Pollution generally results from land runoff, precipitation, atmospheric deposition, drainage, interflow, seepage, and groundwater flow or river course modification. Technically, Non-Point sources are all sources of pollution that are not defined as point sources conveyance (Pegram and Görgens, 2001). Although individual sources may be small, their collective impact can be devastating.
Non-Point pollution of surface waters in South Africa is largely caused by rainfall and the associated surface runoff or groundwater discharge (Pegram and Görgens, 2001). Non-Point Source pollution may be intermittent, contributing to contamination of water resources over a widespread area, such as storm washoff and drainage from urban or agricultural areas. Alternatively, they may be concentrated, associated with localised high activity areas, such as mines, feedlots, landfills and industrial sites. Although Non-Point Source pollution impacts of surface washoff are relatively immediate, the Non-Point Source Pollution impact of groundwater discharge is often delayed, due to the time taken for contaminants to mobilise and move through the soil matrix into the receiving surface water environment (Pegram and Görgens, 2001).
In order to provide strategic direction to research initiatives and to ensure that all important potential Non- Point pollution sectors of the economy are receiving the required attention the Water Research Commission solicited this study “To compile a first order inventory of the quantity and quality of water produced as non-point sources by the South African industrial, mining and power generation sectors, and assess the impact these have on the quality of the water resources”.
Much of the information, needed to compile such an inventory or overview, is available in reports and documents that have been prepared for different purposes. Although much is already known internationally, very little has been published, especially in South Africa, about the quantities and qualities of Non-Point sources produced by different sectors of the economy. As a starting point some of the information needed to compile such an overview, is available in reports and documents that have been prepared for different purposes. Unfortunately most of these reports are specific to point sources. Examples are the NATSURV series of documents (commissioned by the WRC) to provide a benchmark for water use and waste production by major South African industries:
Water and wastewater management in the metal finishing industry (1987)
Water and wastewater management in the soft drink industry (1987)
Water and wastewater management in the dairy industry (1989)
Water and wastewater management in the sorghum malt and beer industries (1989)
Water and wastewater management in the edible oil industry (1989)
1.1 Non-Point Source Pollution Assessment
Water and wastewater management in the red meat industry (1989)
Water and wastewater management in the laundry industry (1989)
Water and wastewater management in the poultry industry (1989)
Water and wastewater management in the tanning and leather finishing industry (1989)
Water and wastewater management in the sugar industry (1990)
Water and wastewater management in the paper and pulp industry (1990)
Water and wastewater management in the wine industry (1993)
In depth literature reviews on the mining industry (Chapter 4), the industrial sector (Chapter 5) and the power generation sector (Chapter 6) were undertaken in an attempt to assist with the first order assessment of Non-Point sources of pollution from these sectors in South Africa. The limited available information on Non-Point pollution has not been compiled into a consolidated overview that presents the total picture for the industrial, mining and power generation sectors. Some of the problems that limit the use of the available information and would necessitate further processing to normalise the data, are that the investigations they are based upon, were done at different times, to different levels of detail and using different approaches. Municipal water use and waste also contain contributions from industry that need to be separated out to get a true value for industries. A further complicating factor is that data for some sectors may not be available and may necessitate further investigation.
The overview of water use and waste production by different sectors needs to be interpreted for the effect sectors can be expected to have on receiving water quality. The mining industry is, for example, reportedly responsible for about 80% of the waste production (salts) in the upper and middle Vaal WMAs (Pulles et al.,1996) and is furthermore, the source of acid mine drainage that is threatening the water quality of several important catchments in the country. However, other industries that produce much smaller quantities of waste may actually present an equal or even more serious threat to water quality in the catchments where they operate, especially if they have waste discard facilities that can be sources of Non-Point pollution after rain or wind events. It would thus be necessary to categorise waste types according to their effect on water quality and synthesise the data to obtain an estimate of the threat that different sectors and sub-sectors pose to receiving water quality.
1.1 Approach and Objectives of study
The general objective of this two-year study was to compile a first order inventory of the quantity and quality of water produced as Non-Point sources by the South African industrial, mining and power generation sectors, and assess the impact these have on the quality of the water resources.
Specific objectives were to:
Evaluate the status quo concerning data available on the quantity and quality of water produced as Non-Point sources by the industrial, mining and power generation sectors, subdivided into useful sub- sectors (literature review that will also use international findings as guidance).
Collect first order data for those sectors and sub-sectors for which insufficient data are available.
Categorise Non-Point sources according to the water qualities and quantities associated with them, and synthesis the data to obtain an estimate of the threat that different sectors and sub-sectors pose to the quality of water resources.
1.2 Non-Point Source Pollution Assessment
Synthesise the current status of the quantity and quality of Non-Point source-affected water associated with the industrial, mining and power generation sectors.
Identify those sub-sectors and Non-Point sources that require research investigation.
A focused literature review reported in Chapter 2, provides an overview of international trends and South African initiatives in Non-Point source pollution. Chapter 3 summarises the different methods and strategies that were followed to collect data for the mining, industrial and power generation sectors. The main contribution of this project is a report for each of the targeted sectors of findings of in depth literature reviews that were undertaken to assist with the first order assessment of their Non-Point sources of pollution. These are reported for the mining industry (Chapter 4), the industrial sector (Chapter 5) and the power generation sector (Chapter 6). The findings of this investigation are discussed in Chapter 7 and some conclusions and recommendations are made.
1.3 Non-Point Source Pollution Assessment
2 LITERATURE REVIEW
2.1 International trends
According to Campbell et al. (2004), Non-Point pollution (or as it is used in the report Non-Point sources of pollution) is the unfinished business of water pollution control that was recognised as a problem in the 1970s. For many years technology, business practice and regulatory activity have been developing to achieve even tighter control of major effluent discharges such as industrial process effluents and municipal sewage discharges. The building of sewers and treatment plants in developed countries has been continuing for more than one hundred years and achieved remarkable successes (Campbell et al., 2004). Today, in many countries, Non-Point pollution is now the biggest remaining problem. It should not be thought that it is a new problem, however, rather its impacts were formerly masked by gross pollution from the major point sources noted above (sewage and industrial effluents) (Campbell et al., 2004).
The term Non-Point pollution has evolved from an earlier recognition of two categories of pollution sources:
Point source; and
Non-Point source (Campbell et al., 2004).
Novotny (2003) explains that the statutory definition of point and Non-Point sources has important regulatory ramifications and that traditional point sources of wastewater – municipal, industrial and agricultural discharges- are different from Non-Point sources, in that, according to the expanded universal definition of Non-Point sources, they encompass both point and Non-Point sources (Novotny, 2003).
The traditional point sources strictly include: wastewater effluents from industrial sites, from indoor farm operations and from deep mines. Whereas runoff from storm sewers, construction sites or concentrated animal feeding operations are classified both as point and Non-Point Source Pollution (Novotny, 2003). This last kind of pollution originates from land use activities, it is intermittent and occurs mostly during meteorological factors and usually enters the receiving water system through an unidentified discharge outlet (Novotny, 2003). Thus the practical definition of Non-Point sources and pollution proposed in the United Kingdom (D’Arcy et al., as quoted by Novotny, 2003): “Pollution arising from land-use activities (urban and rural) that are dispersed across a catchment and do not arise as a process industrial effluent, municipal sewage or deep mine sewage”.
The following characterisation is thus given for Non-Point sources (Novotny, 2003):
Non-Point discharges enter receiving surface water in a Non-Point manner at intermittent intervals that are primarily related to meteorological events;
Waste generation (pollution) arises over an extended area of land and is in transit overland before it reaches surface waters or infiltrates shallow aquifers;
Non-Point sources are difficult to monitor at the point of origin;
Unlike traditional sources, where treatment is the efficient method for abatement, control of Non-Point pollution is based on land and runoff best management practices;
Compliance monitoring is implemented on land rather than in water;
Waste emissions and discharges cannot be measured in terms of effluent limitations;
The most important waste constituents from Non-Point sources subject to management and control are suspended solids, nutrients and toxic compounds.
2.1 Non-Point Source Pollution Assessment
A clear distinction was drawn between point sources and Non-Point sources (Department of Water Affairs and Forestry-DWAF, 2003). The following sources have been classified among point sources:
Outfall pipe from any activity classified as a water use
Storm water outfall pipe
Irrigation point
Run-off channels and sub-surface drains
Controlled-release dam
Landfill leachate
Whereas Non-Point sources are to be cited as those that are often difficult to link to the source, because they enter the receiving water over a large area, where they could be mixed with discharges from other sources (DWAF, 2003). They are usually difficult to measure because they are highly variable as a result of hydrological processes that vary over time. Waste typically enters the water resource due to seepage, leaching and run-off (DWAF, 2003).
Principal Non-Point sources according to DWAF (2003) are:
Dams and water impoundments
Landfill sites
Irrigated agriculture
Irrigation of waste
Dryland agriculture
Mine and industrial dumps and excavations
Confined livestock enclosures
Urban activities
General urban waste
Spills
Table 2.1 classifies some Non-Point source pollutants according to their sources and the associated water quality impacts.
2.2 Non-Point Source Pollution Assessment
Table 2.1: Classification of Non-Point source pollutants according to their sources and the impacts involved (Heath, 2001) POLLUTANT SOURCES WATER QUALITY AND RELATED IMPACTS
Forestry Urban runoff Agriculture Create human health hazard Faecal bacteria Urban Run-off Increase costs of treating drinking water
Reduce recreational value
Adversely affect reproduction rates and life spans of aquatic organisms
Adversely disrupt food chain in aquatic environments Urban runoff Industrial runoff Metals Accumulate in bottom sediments, posing risks Mining to bottom feeding organisms Automobile use Accumulate in tissues of plants, macro invertebrates, and fish
Reduce water quality
Agriculture Over stimulate growth of algae and aquatic Forestry plants, which later through their decay reduce Nutrients (phosphorous, Urban runoff oxygen levels nitrogen) Construction High concentrations of nitrates can cause health problems in infants
Kill aquatic organisms that are not targets
Adversely affect reproduction, growth, respiration, and development in aquatic organisms Agriculture Forestry Reduce food supply Pesticides Urban runoff Herbicides Accumulate in tissues of plants, macro invertebrates, and fish
Reduces recreational and commercial activities
Increased organisms susceptibility to diseases
Decrease species diversity
Urban runoff Reduce crop yield
Industrial runoff Decrease quality of drinking water Salts Automobile use Increase exposure of water treatment Mining Reduce recreation values through high salinity levels and high evaporation rates
2.3 Non-Point Source Pollution Assessment
POLLUTANT SOURCES WATER QUALITY AND RELATED IMPACTS
Decreases water clarity
Agriculture Adversely affects respiration of fish Forestry Sediment Urban runoff Smothers fish eggs Construction Mining Decreases dissolved oxygen concentrations
Decreases quality of drinking water
2.2 South African Research Initiatives in Non-Point Sources Pollution
It is now accepted that it is not feasible to properly manage water quality without addressing the contribution from Non-Point sources. Consequently, attention is increasingly being devoted to the quantification of Non-Point Source Pollution and to identify means to control it cost-effectively at source. The WRC has also recognised that Non-Point pollution needs to be assessed in South Africa and funded a large project on agricultural Non-Point pollution (including modelling and some experimentation) (WRC K5/1467).
This project aims to determine at a scoping level, the quantity and quality of Non-Point Source Pollution that originates from the mining, industrial and power generation sectors. This information will further be used at a strategic level, to determine whether the present investment in research in this KSA and more specifically the thrust concerned with industrial and mine-water management, reflects the need in this regard.
The limited available information on Non-Point pollution has not been compiled into a consolidated overview that presents the total picture for the industrial, mining and power generation sectors (Chapters 4, 5 and 6). Some of the problems that limit the use of the available information and would necessitate further processing to normalise the data, are that the investigations they are based upon, were done at different times, to different levels of detail and using different approaches. Municipal water use and waste also contain contributions from industry that need to be separated out to get a true value for industries. A further complicating factor is that data for some sectors may not be available and may necessitate further investigation.
Further benefit could be added by an analysis and categorisation of the available data into environmental life cycle assessment categories such as global warming, ozone depletion, nitrification, acidification, human toxicity, aquatic toxicity, aquatic toxicity, terrestrial toxicity, salinisation, energy use, resource use, etc.
It is important that an overview such as envisaged with this project produces credible results. It is therefore necessary to verify the findings of the study with practitioners in the field. Presenting and discussing the results at one or more workshops can achieve this, for example. In conducting this investigation, it is important to bear in mind that striving for maximum accuracy is neither necessary nor desirable.
The overview of the quantities and qualities of Non-Point source effluent production by different sectors needs to be interpreted in terms of the effect the effluent can be expected to have on receiving water quality (both surface and groundwater). It would thus be necessary to categorise waste types according to their effect on water quality and synthesise the data to obtain an estimate of the threat that different sectors and sub-sectors pose to receiving water quality.
2.4 Non-Point Source Pollution Assessment
3 METHODS AND STRATEGY FOR DATA COLLECTION
The methods and strategies for data collection varied between the different sectors of potential Non-Point pollution. Consistent shortages in published literature were found in all three of the sectors under study.
3.1 The Mining Industry
A literature review was undertaken for Non-Point Source Pollution and the mining industry information (international and South African). From the literature review and meetings with Department of Minerals and Energy, DWAF and mining houses it was clear that the data on the mining contribution to Non-Point pollution is not readily available.
The following methods of data collection were used to gain information from the mining industry:
Presentations:
- WISA 2006 (Durban May 2006).
- Heath et al. (2006) Diffuse pollution associated with the mining sectors in South Africa – A first order assessment.
- Chamber of Mines (September 2006)
A presentation at the Chamber of Mines to the environmental representatives of the major mining houses.
Meetings
Table 3.1 reflects a list of the industries that meetings were held with.
These meetings did not bring anything new to the table except that Non-Point pollution is recognised as a contributor to both surface and groundwater pollution.
The detailed findings of the mining industry in South Africa data collection is indicated in Chapter 4.
3.1 Non-Point Source Pollution Assessment
Table 3.1 List of Companies / People consulted for Industrial Non-Point Source Information
COMPANY / INSTITUTION CONTACT PERSON
Major Mining Houses
Chamber of mines Niks Lusufi
AngloCoal Dr Mark Aken
Billie van Zyl
Power Generation Industry
Marius Keet
Garreth McConkey Department of Water Affairs and Paul Herbst Forestry (DWAF) Marlene Kuneke
Thorston Aab
Kobus du Toit
Karl-Heinz Riedel
Sasol Corne Pretorius
Joey Swart
Dr Trevor Phillips
SAPPI Tony Leske
SAAFOST workshop delegates (5 September, University of SAAFOST Stellenbosch)
Water & Waste Solutions Buks Schutte
Andrew Brown Golder Andre van Niekerk
NCP Don Kinsey
Industrial
Organization Contact Person
Eskom Dirk Hanekom / Bongonkosi Nyembe
Eskom Holdings : Resources & Kristy Ross / Siven Naidoo Strategy Division
Rooiwal Power Station Sandra de Beer
3.2 Non-Point Source Pollution Assessment
COMPANY / INSTITUTION CONTACT PERSON
Kelvin Power Station Dianna Sponneck
Department of Environmental Affairs Mr T Mahema and Tourism
3.2 Industry
The first task was to do a literature review in order to obtain background data on the situation in South Africa and worldwide. Although a very large number of references containing key words of, Non-Point, diffuse pollution and industry were obtained, few of them actually contained useful information for the purpose of this study. Very little information on industrial diffuse pollution in South Africa could be found in the literature. A brief summary is given in the literature review section (sections 5.2 and 5.3).
A number of personal interviews were conducted with representatives of some industries and other individuals from DWAF and other institutions (Table 3.1).
It must be pointed out that although there is a large amount of information available in the form of reports on special investigations conducted for individual industries; this data is not readily available because industries in general feel uncertain about how this type of information could affect their situation with regard to future applications for water use or wastewater discharge.
In an attempt to validate the information on the lists and more specifically the approach to assign a risk factor to the different categories, a workshop was arranged as part of the WISA conference in Durban in 2006. A presentation was made at the workshop on the industrial sector project and some useful discussions took place. However, most of the workshop contributions were in the form of general remarks and general discussions and not much specific information was obtained.
As a follow-up to the workshop, the list containing industry categories with potential pollutants and risk factors was distributed to all the members of the Water Industry of Southern Africa Industrial Water Specialist Group with the request to comment and to provide and/or correct information on the list. A relatively small number of comments were received.
In our view the lack of response can be contributed to the fear by industry that this project might result in further demands and requirements and possibly penalties. Furthermore they wish to stay away from anything that might result in any demand on their time since they are already over burdened with administrative requirements.
It was therefore decided not to arrange a general workshop but rather to conduct mini workshops with representatives of selected industries in an attempt to get commitment and hopefully better information.
After discussions with the Steering Committee it was agreed that some of the major industries, or industrial complexes, be approached for data. Mini workshops were held with representatives of five such industries. The same issues prevalent at all these workshops which pertaining to confidentiality of data. Despite some of these industries making data available it has not been included in this report due to the potential sensitivity of the data.
The detailed findings of the industrial sector in South Africa data collection is indicated in Chapter 5.
3.3 Non-Point Source Pollution Assessment
3.3 Power Generation
As this project is only a first order assessment it was focussed only on the most relevant and important information readily available and precluded fieldwork and sampling. A range of qualitative and quantitative air and water quality data related to the power generation sector was collected from various literature resources as well as communication with various role players. A draft report, “A first order assessment of the quantity and quality of Non-Point sources of pollution associated with the power generation sector”, containing all relevant data was compiled.
Due to the difficulty in scheduling a workshop specifically for the power generation sector it was decided (and approved by the project leader) to send the draft report via e-mail to the various role players for verification and comments (See Table 3.1 for details).
The report was sent to the following entities:
Eskom
Eskom Holdings – Resources & Strategy Division
Rooiwal Municipal power station
Kelvin Municipal power station
A list of all the role-players to whom the report was sent and their details are provided in Table 3.1. Comments, follow-up meetings and phone calls with these contacts have been included into this report. The detailed findings of the power generation sector in South Africa data collection is indicated in Chapter 6.
3.4 Non-Point Source Pollution Assessment
4 NON-POINT POLLUTION AND THE MINING SECTORS OF SOUTH AFRICA
4.1 Introduction
South Africa is globally recognised as being a leading supplier of a variety of minerals and mineral products. South Africa’s mineral wealth is found in diverse geological formations, some of which are unique and extensive by world standards. South Africa holds the world’s largest reserves of ores of platinum-group metals, manganese, chromium, vanadium, gold and alumino-silicates (DME, 2004). It is also prominent in terms of reserves of: titanium, zirconium, vermiculite, and fluorspar (DME, 2004). More than 20 different types of precious metals and minerals, energy minerals, non-ferrous metals and minerals as well as ferrous minerals are mined in South Africa (DME, 2004). From 1976, South Africa’s coal exports have increased rapidly on the strength of the country being one of the world’s most reliable suppliers (DME, 2003).
Environmental impacts of mining lead to changes to land usage and surface and ground water quality. South Africa produces around 450 million tonnes of waste annually, with 70% of this generated by the mining industry (AngloGold Ashanti Annual Report 2004). Surface mining became a more prominent activity at the beginning of the twentieth century, to reduce cost over that of deep mines pollution (Novotny, 2003). Surface mining of coal leaves large areas of land bare, without vegetation and soils. The land is often covered with waste rocks that have been separated from the coal, as well as residual coal materials. Only recently, re-cultivation and environmental restoration efforts in developed countries have brought lands of abandoned surface mines to some use, such as forestry and agriculture pollution (Novotny, 2003).
Until the advent of strict environmental controls in the mining industry, in the latter part of the twentieth century, discard was generally dumped in an ad hoc manner. This practice created further environmental issues as both the atmosphere and the ground water became seriously polluted (DME, 2003). Currently, discard is being dumped in a far more circumspect and professional manner inhibiting the ingress of air into the discard dump, as well as the reduction of the permeability of the discard dump. This prevents natural rainwater, accumulated at the top of the dump from seeping through the dump and causing ground water pollution.
Mining cannot be viewed as a homogeneous source of Non-Point pollution (Novotny, 2003). The most common minerals extracted by mining are coal and metallic ores. Mining Non-Point pollution sources include discharges from inactive mining operations, as well as runoff from roads, old tailings and spoil piles pollution (Novotny, 2003).This is usually as a result of non-performance of the responsible parties such as the State, mines, regulators, etc. Active mines are considered as point sources for which a discharge permit is required. Sediment discharges and concentrations from mines can be extremely high; furthermore, entire streams may be biologically dead as a result of AMD. Erosion and sedimentation problems are associated with pollution of almost every abandoned surface coalmine (Novotny, 2003). Other pollutants associated with mining operations can have even more serious water quality impact than those associated with sediments pollution (Novotny, 2003).
South African is facing major problems with regard to the management and treatment of contaminated mine water. These problems exist with regard to operational mines, and importantly, they also exist for mines which have ceased operations and which have long-term water quality problems.
4.1 Non-Point Source Pollution Assessment
4.2 Main environmental regulatory tools currently available in South Africa to manage mining activities
The section below deals briefly with the main environmental regulatory tools currently available in South Africa to manage mining activities with special emphasis on management of Non-Point pollution.
4.2.1 Constitution of the Republic of South Africa Act (Constitution) (Act 108 of 1996)
Certain of the fundamental rights contained in the Constitution are closely associated with financial provision, rehabilitation and closure aspects of mining activities (Heath and Eksteen, 2005). These include in particular section 24 (“Environment”) and section 33 (“Just Administrative Action”). Section 24 of the Constitution provides that “everyone has the right … to an environment that is not harmful to their health or well-being; and to have the environment protected for the benefit of present and future generations through reasonable legislative and other measures that – (i) prevent pollution and ecological degradation; (ii) promote conservation; and (iii) secure ecologically sustainable development and use of natural resources while promoting justifiable economic and social development”. Section 33 of the Constitution entitles everyone to administrative action that is lawful, reasonable and procedurally fair and, if one’s rights have been adversely affected by administrative action, to be given written reasons for the decision.
4.2.2 National Environmental Management Act (NEMA) (Act 107 OF 1998)
The National Environmental Management Act (NEMA) stipulates certain environmental management principles that apply throughout the country to the actions of all organs of state that may significantly affect the environment (Heath and Eksteen, 2005). These include, amongst others:
Sustainable development
Risk aversion and precaution
Integrated environmental management
Environmental justice
Equitable access (redressing issues of the past)
Cradle to grave (life cycle)
Public participation and consultation
Internalisation of costs (polluter pays)
Beneficial use of natural resources
In the context of mining, these principles are given further effect through the Mineral and Petroleum Resources Development Act (MPRDA, Act 28 of 2002), which stipulates that the principles set out in NEMA apply to all prospecting and mining operations and any matter relating to such operation and serve as guidelines for the interpretation, administration and implementation of the environmental requirements of the MPRDA (Heath and Eksteen, 2005).
NEMA further establishes a general duty of care on every person who causes, has caused or may cause significant pollution or degradation of the environment to take reasonable measures to prevent such pollution or degradation from occurring, continuing or recurring, or, in so far as such harm to the environment is authorised by law or cannot reasonably be avoided or stopped, to minimise and rectify such pollution or degradation of the environment (Heath and Eksteen, 2005).
4.2 Non-Point Source Pollution Assessment
4.2.3 National Water Act (NWA) (Act 36 of 1998)
The National Water Act (NWA) iterates the general duty of care on persons who own, control, use or occupy land on which any activity or process is or was performed or undertaken, or any other situation exists which causes, has caused or is likely to cause pollution of a water resource, to take all reasonable measures to prevent any such pollution from occurring, continuing or recurring (Heath and Eksteen, 2005). Regulations on use of water for mining and related activities aimed at the protection of water resources, was promulgated in terms of the NWA in 1999 and address, amongst others, the following issues that have direct relation to rehabilitation and mine closure:
Notification of the temporary or permanent cessation, or resumption, of a mining or related activity
Design, modification, construction and maintenance of pollution control measures
Remediation of in-stream and riparian habitats of water resources affected by mining or related activities
Concurrent rehabilitation and compaction of coal residue deposits
Detailed studies to evaluate and manage certain aspects related to the specific mine or activity, which could include rehabilitation and/or closure aspects
Management responsibilities, including making available the necessary financial and human resources, training and education, management structures, contact with expertise for necessary investigations, etc. (Heath and Eksteen, 2005).
4.2.4 Mineral and Petroleum Resources Development Act (MPRDA) (Act 28 of 2002)
The MPRDA stipulates that the holder of reconnaissance permission, prospecting right, mining right, mining permit or retention permit (hold):
Must at all times give effect to the general objectives and principles of integrated environmental management laid down in National Environmental Management Act (NEMA) (Act 107 of 1998)
Must consider, investigate, assess and communicate the impact of his or her prospecting or mining on the environment
Must manage all environmental impacts in accordance with his or her environmental management plan or programme (EMP) as an integral part of the reconnaissance, prospecting or mining on the environment
Must as far as it is reasonably practicable, rehabilitate the environment affected by the prospecting or mining operations to its natural or predetermined state or to a land use which conforms to the generally accepted principle of sustainable development
Is responsible for any environmental damage, pollution or ecological degradation as a result of his or her reconnaissance, prospecting or mining operations and which may occur inside and outside the boundaries of the area to which such right, permit or permission relates (Heath and Eksteen, 2005).
Furthermore, the MPRDA requires that any prospecting or mining operation must be conducted in accordance with generally accepted principles of sustainable development by integrating social, economic and environmental factors into the planning and implementation of prospecting and mining projects in order to ensure that exploitation of mineral resources serves present and future generations (Heath and Eksteen, 2005).
4.3 Non-Point Source Pollution Assessment
The MPRDA further stipulates that no person may prospect for or remove, mine, conduct technical co- operation operations, reconnaissance operations, explore for and produce any mineral or petroleum or commence with any work incidental thereto on any area without inter alia an approved environmental management programme or plan (EMP), as the case may be (Heath and Eksteen, 2005). This requirement is further supported in the mineral and petroleum resources development (MPRD) regulations that stipulate specific technical and procedural requirements for environmental management programmes and/or plans and monitoring and performance assessments (Heath and Eksteen, 2005).
The MPRDA further requires that an applicant for a prospecting right, mining right or mining permit must, before the said EMP will be approved, make the prescribed financial provision for the rehabilitation or management of negative environmental impacts (Heath and Eksteen, 2005). The quantum of the financial provision must be based on the requirements of the EMP and shall include a detailed itemisation of all actual costs required for:
Pre-mature closure regarding the rehabilitation of the surface and prevention and management of pollution of the atmosphere, water and soils
Decommissioning and final closure of the operation; and
Post-closure management of residual and latent environmental impacts.
The MPRDA further requires the holder of a prospecting right, mining right or mining permit to annually assess his or her environmental liability (in consultation with a competent person) and revise his or her financial provision accordingly (Heath and Eksteen, 2005). The requirement to maintain and retain this financial provision remains in force until a closure certificate has been issued.
The holder of will remain responsible for any environmental liability, pollution or ecological degradation, and the management thereof, until a closure certificate has been issued. An application for a closure certificate must be made within a specified time (180 days) of the occurrence of the lapsing, abandonment, cancellation, cessation, relinquishment or completion of an operation and must be accompanied by a prescribed environmental risk report (Heath and Eksteen, 2005). The environmental risk assessment (ERA) process to be followed during the development of the said report is prescribed in detail in the MPRD regulations and must include the financial provision for long-term monitoring and maintenance and/or post-closure management of any latent or residual environmental impact identified during the ERA. When a closure certificate is issued, the financial provision will be returned to the holder; however, a portion required to manage latent of residual environmental impacts may be retained (Heath and Eksteen, 2005).
4.2.5 Rehabilitation of Derelict and/or Defunct Mines for which no owner exists or can be traced
Derelict and/or defunct mines are those mines or portions of mines in respect of which operations have ceased and where no legally responsible person or owner exists or can be identified (Heath and Eksteen, 2005). In such circumstances and where the State has not already accepted responsibility or co- responsibility in terms of existing agreements, the Minister of Minerals and Energy with the concurrence of the Minister of Finance shall accept responsibility or co-responsibility for the rehabilitation required and may order the cost involved to be paid by the State out of funds appropriated by Parliament for this purpose and by anyone who will benefit from such rehabilitation, in such proportion as may be determined taking into account the practicality and equity in requiring a person to contribute (Heath and Eksteen, 2005). The persons referred to above may include persons such as the landowner or a regional authority but does not include the mining industry as a whole.
4.4 Non-Point Source Pollution Assessment
4.2.6 Mine Health and Safety Act (MHSA) (Act 29 of 1996)
The MHSA stipulates that the employer (owner) of a mine that is not being worked, but in respect of which a closure certificate has not been issued, must take reasonable steps to prevent injuries, ill-health, loss of life or damage of any kind from occurring at or because of the mine (Heath and Eksteen, 2005).
4.2.7 National Environmental Management Air Quality Act (2004)
National ambient air quality standards for criteria pollutants have been issued by the Department of Environmental Affairs and Tourism (DEAT). These guidelines have been revised and ambient air quality standards have been enforced with the introduction of the National Environmental Management Air Quality Act 2004. The new Air Quality Act makes provision for the formulation of ambient air quality standards “for substances or mixtures that pose a threat to health, well being or the environment”.
With the introduction of the new Act, listed activities which “result in atmospheric emissions and are regarded to have a significant detrimental effect on the environment, including human health” will be identified by the Minister of Environmental Affairs and Tourism. Once published, atmospheric emission standards will be established for each of these activities and an atmospheric emission license will be required to operate.
4.2.8 National Heritage Resources Act (NHRA) (Act 25 of 1999)
NHRA stipulates that a permit is required to alter or demolish any structure or part of a structure, which is older than 60 years from the relevant provincial heritage resources authority (Heath and Eksteen, 2005). Various other forms of protection may also apply.
4.2.9 Cooperative Governance
The spirit of the applications of the various Acts and regulations in South Africa is one of co-operative governance (Heath and Eksteen, 2005). As can be seen above no single Act or government department has total control over the mining and environmental issues. Consequently it is important that the government department co-operate and share the application of applying the legislation in a sustainable manner (Heath and Eksteen, 2005).
4.2.10 Other forms of Regulatory Assistance
A number of other environmental tools/instruments are currently employed (or in certain cases being developed) in South Africa to assist with the day-to-day management of mining activities (Heath and Eksteen, 2005). These include:
Command and control instruments
- Waste discharge standards (water, air quality) - Licensing (water use and waste disposal)
- Monitoring and auditing requirements
Best practice guidelines
- Guidelines on financial provision – DME
- Best practice guidelines for water quality management in the SA mining industry – DWAF
4.5 Non-Point Source Pollution Assessment
Market-based instruments
- Pollution taxes (waste discharge charges) - Tradable permits (water use) - Triple bottom-line accounting
- International pressure for green products (eco-labelling)
Social instruments
- Performance reporting - Public participation and consultation
- General duty of care
Industry co-regulation / self-regulation
- Environmental Management Systems (ISO 14001)
- Internal HSEC reporting and performance requirements (waste minimisation, reduction in use of natural resources)
- International norms and pressures (multinational companies mining in South Africa and trading partners)
4.3 Types of mining
A variety of mining methods are used to extract minerals and the particular method used depends on the type, depth, extend and dip of the mineral deposit. Only the more commonly used methods are mentioned here:
Strip or open cast mining
Open-pit mining
Dredge mining
Dump reclamation
Shallow underground mining
Deep underground mining (Wilson and Anhaeusser, 1998).
The potential Non-Point sources of pollution associated with the different mining types varies according to the type of community mined. For example a diamond open case mine will mainly result in sediment (turbidity) contamination to the surface and groundwater. The same type of mining method for coal will, however, result in acid mine drainage (AMD) contamination (low pH, high metals and salts) due to pyrite associated with the coal. The typical types of Non-Point sources of pollution that can be associated with the mining industry are discussed in section 4.4.
4.6 Non-Point Source Pollution Assessment
4.4 Overview of Non-Point pollution involved with the mining sector
Typical pollutants from the mines include sulphates, acidity, salinity and metals (including aluminium, iron and manganese) and may contribute to the three types of Non-Point pollution caused by mining, i.e. surface water, groundwater and atmospheric pollution (Heath and Eksteen, 2005).
The set of impacts any specific mining activity will have on aquatic environment is mainly linked with: The type of rock and ore being mined
The type of mining operation and the scale of operations
The efficiency of environmental systems implemented by the mine management and
The sensitivity of the receiving environment (Ashton et al., 2001).
4.4.1 Non-Point Pollution contributing to Surface and Groundwater Pollution
Pyrite plays an important part in the process of AMD generation as AMD derives part of its acid character from hydrated iron (Bullock et al., 2001). Hydrated iron is formed during the initial oxidation of pyrite. Hydrated iron promotes the additional oxidation of fresh pyrite and other minerals. The primary chemical factors which determine the rate of acid generation include pH value, temperature, and oxygen content of the gas phase if saturation is less than 100%, concentration of oxygen in the water phase, degree of saturation with water, chemical activities of Hydrated iron, surface area of exposed metal sulphide and the chemical activation energy required to initiate acid generation. In addition, the chemolithotropic bacteria Thiobacillus ferrooxidans may accelerate the reaction by its enhancement of the rate of ferrous iron oxidation. It also may accelerate action through its enhancement of the rate of reduced sulphur oxidation. T ferrooxidans is most active in waters with a pH value around 3.2 and further converts the ferrous iron of pyrite to its ferric form. The formation of sulphuric acid in the initial oxidation reaction and concomitant decrease in the pH make conditions more favourable for biotic oxidation of the pyrite by T ferrooxidans. The biotic oxidation of pyrite is four times faster than abiotic reaction at pH 3.0. The development of AMD is a complex combination of inorganic and sometimes organic processes and reactions. In order to generate severe AMD (pH <3), sulphide minerals must create an optimum micro- environment for rapid oxidation and must continue to oxidise long enough to exhaust the neutralisation potential of the rock. These low pH waters then dissolve metals in the waste rock dump and surrounding rocks, resulting in a final leachate containing high concentrations of aluminium, zinc, iron, copper, lead, arsenic, cadmium, nickel and magnesium.
4.4.2 Non-Point Pollution contribution to Air Pollution
Atmospheric emissions related to mining activity are generally restricted to the release of particulate matter in the form of dust (Foster, 1998). Dust control is a common feature of almost all mining operations. Dust arises from a combination of the following sources:
Soil stripping and overburden removal
Blasting and rock fragmentation
Primary crushing and product distribution systems, e.g. screens, chutes, conveyors
Waste rock storage dumps
Process tailings facilities
Internal haul roads and supporting infrastructure (Foster, 1998).
4.7 Non-Point Source Pollution Assessment
The environmental significance of dust dispersion at a mine site depends on local topographical and climatic conditions and the type of mining undertaken (Foster, 1998). Dust generation from underground mining activity may differ little from that generated at open-pit mines if it is largely related to surface movement and storage of product and waste materials (Foster, 1998).
Although the presence of elevated particulate matter in the atmosphere produces a reduction in air quality, it is rarely the case that emissions from mining activity lead to concern about air quality deterioration (Foster, 1998). Problems relating to dust dispersion are more often associated with deposition and the implications for soil contamination, vegetative uptake or contamination of water resources (Foster, 1998).
Dust control at mine sites is a well-established activity but one that is rarely afforded anything but the most basic of control techniques (Foster, 1998).
In all cases traditional methods of dust control rely on dust suppression with the use of water, which is liberally spread over haul roads, waste dumps and process plant as necessary (Foster, 1998). The effectiveness of this approach is dependent on the ability to maintain continuous water distribution (Foster, 1998).
Emissions from mining can result in nuisance conditions for local communities at mine sites where dust is a continuous problem, consideration is increasingly being given to the use of wetting agents and foam additives to reduce dust generation and minimise water usage (Foster, 1998). A variety of wetting agents and chemical reagents are available commercially. Most products work by promoting haul road compaction and dust agglomeration (Foster, 1998). Other products, primarily foaming agents, are used to improve dust control at primary processing locations. The economic and environmental benefits associated with the use of dust suppression media have yet to be fully established. There is evidence to suggest that at large mines where dust is a major concern, improved capability to manage dust emissions may be achieved by use of these products (Foster, 1998).
In many mining situations the greatest dust related concerns are not those associated with the surrounding environment but those related to the working environment at the mine (Foster, 1998). There can be health risks for employees associated with poorly controlled dust emissions, ranging from host rock-related dust problems such as silicosis, to ore-related problems generally related to heavy metal toxicity (Foster, 1998). A secondary issue that may arise is that of undesirable odours associated with process gas emissions (Foster, 1998). This can be particularly significant where mining operations are located close to centres of population (Foster, 1998).
Addressing the issue of tailings storage facilities, the mining mineral and sustainable development project (Mining Minerals and Sustainable Development, 2002) noted that old tailings storage facilities, in Gauteng Province, generate dust that can be blown over several kilometres. During the dry months the dust is overpowering, and that local people are forced to take up their windows and doors in an effort to keep it out (MMSD, 2002).
The overview of water use and waste production by different sectors needs to be interpreted for the effect sectors can be expected to have on receiving water quality. The mining industry is, for example, reportedly responsible for about 80% of the waste production (salts) and is furthermore, the source of acid mine drainage that is threatening the water quality of several important catchments in the country. However, other industries that produce much smaller quantities of waste may actually present an equal or even more serious threat to water quality in the catchments where they operate, especially if they have waste discard facilities that can be sources of Non-Point pollution after rain or wind events. It would thus be necessary to categorise waste types according to their effect on water quality and synthesise the data to obtain an estimate of the threat that different sectors and sub-sectors pose to receiving water quality.
4.8 Non-Point Source Pollution Assessment
Further benefit could be added by an analysis and categorisation of the available data into environmental life cycle assessment categories such as global warming, ozone depletion, nitrification, acidification, human toxicity, aquatic toxicity, aquatic toxicity, terrestrial toxicity, salinisation, energy use, resource use, etc.
It is important that an overview such as envisaged with this project produces credible results. It is therefore necessary to verify the findings of the study with practitioners in the field. Presenting and discussing the results at one or more workshops can achieve this, for example. In conducting this investigation, it is important to bear in mind that striving for maximum accuracy is neither necessary nor desirable.
4.5 South African mining industry
As indicated in section 4.1 the mining industry in South Africa is one of the major world forces especially with regards to platinum based metals, manganese, chromium, vanadium, coal and gold. There is a vast array of literature on the production per commodity but there is a scarcity of information on the Non-Point Source Pollution impacts of mines. Due to the voluminous reports on the different commodities mined in South Africa the literature reviews have been included in separate Appendices. The Appendices are as follows and can be found on the enclosed CD:
Appendix A: Gold
Appendix B: Coal
Appendix C: Platinum
Appendix D: Diamonds
Appendix E: Iron
Appendix F: Titanium
Appendix G:Sand
Appendix H: Manganese
Appendix I: Radioactivity
Appendix J: Organics
Appendix K: Base metals
Appendix L: Chromium
Appendix M: Vanadium
Water and air pollution are both serious problems associated with the mining and processing. The environmental impact of mining and processing operations is dependent on the type of commodity mine, type of mining method, grade of ore and the processes used. Typical gold mining impacts are indicated in Table 4.1. Non-Point sources are usually difficult to measure because they are highly variable as a result of hydrological processes that vary over time. Mine water waste typically enters the water resource due to seepage, leaching and run-off (DWAF, 2003). Principal Non-Point sources according to DWAF (2003) are:
Dumps (waste rock, slimes dams,
Excavations (surface and groundwater)
4.9 Non-Point Source Pollution Assessment
Dams and water impoundments
Landfill sites
Irrigation of waste
Spills from pollution control dams, pipelines. slimes dams
The potential pollutants and where to look while investigating on gold pollution are summarised in Table 4.1 (Pulles et al., 1995). The typical sources on the mine and the areas that are affected by the contaminated effluents are also given. The difficulties associated with Non-Point Source Pollution are in the quantification – how much pollution and when?
Table 4.1: Gold associated pollutants (Pulles et al., 1995; Pulles et al., 1996)
CONTAMINANTS TYPICAL SOURCE AREAS AFFECTED
Metals: Iron, arsenic, Pyrite oxidation in underground Sediments, groundwater, surface manganese, zinc, lead, stopes & surface rock and sand waters, macrophytes, biota copper dumps & slimes dams with dissolution of metals
Sulphate Pyrite oxidation in underground Sediments, groundwater, surface stopes and surface rock and waters sand dumps & slimes dams to produce sulphates
Cyanide Spillage from: plant areas, Sediments, groundwater, surface ruptured slimes delivery water, macrophytes, biota pipelines and slimes dams
Suspended solids Inadequate underground Sediments, groundwater, surface settling, runoff from surface waters, biota rock, sand dump &slimes dams
Sodium Fissure water, addition of Sediments, groundwater, surface sodium based neutralisation waters, macrophytes, biota chemicals
Chlorides Fissure water Sediments, groundwater, surface waters, macrophytes, biota
Nitrogen compounds Wastes explosives, gas by- Groundwater, surface waters products from explosives, sewage and contaminated runoff from hostels
Phosphates Sewage and contaminated Groundwater, surface waters runoff from hostels
Acidity Pyrite oxidation underground, Groundwater, surface waters, surface dumps(rock, sand, macrophytes, biota slimes), spillage from plant areas
Radionuclides Pyrite oxidation in underground Sediments, groundwater, surface stopes &surface rock and sand waters, macrophytes, biota
4.10 Non-Point Source Pollution Assessment
CONTAMINANTS TYPICAL SOURCE AREAS AFFECTED
dumps &slimes dams with dissolution of radionuclides
Microbes: Faecal coliforms Faecal contamination of u/g Sediments, groundwater, surface coliphages mine service water, poorly waters, macrophytes, biota treated sewage, runoff from hostel areas, livestock grazing
4.6 Classification of Non-Pollution Types Associates Mining Industry
4.6.1 Risk analysis
Typical contaminants were identified which could potentially have an impact on Non-Point Source Pollution, e.g. metal concentration and a risk factor given to each ranging between 0 (not ranked) and 4 (high risk). Typical sources of pollution were then identified, e.g. waste rock dumps, slimes dams, etc. A risk factor was given to each source type of pollution. The risks relate to the potential of the contaminant that originates from a specific source to pollute either the surface, atmosphere or groundwater.
The risk factor allocated to each contaminant was then multiplied by the risk factor given to the source type of pollution and the individual results totalled to give a contaminant risk factor (Tables 4.2-4.8). It must be noted that the amount of information available on the contaminants for a certain mining commodity influences the contaminant risk factor and may skew the results. Therefore, the contaminant risk factor was corrected for the amount of contaminants identified to be present by dividing the contaminant risk factor by the amount of contaminants identified.
Thereafter the amount of ore milled/run of mill had to be incorporated into the risk analysis. Table 4.2 summarises the risk factors allocated per run of mill/ore milled. Table 4.3 summarises the risk factors allocated to each mining commodity investigated based on the run of mill/ore milled for the period 2000-2004 (DME, 2005).
Table 4.2: Risk factor associated with run of mill/ore milled
RUN OF MILL/ORE MILLED RISK FACTOR
<100,000,000 25
100,000,001-499,000,000 50
500,000,000-999,000,000 75
>1,000,000,000 100
It must be noted that the above risk factor assessment table might work for the run of mill/ore milled for large commodities mined but coal mining, even at a low volumes, will always have a high risk factor due to its potential the generation of acid mine drainage.
The risk factor associated with the run of mill/ore milled was then multiplied by the (typical contaminants risk factor divided by the contaminants present) associated with each mining commodity (Table 4.3-4.7)
4.11 Non-Point Source Pollution Assessment to determine the potential magnitude each mining commodity has on Non-Point Source Pollution (Table 4.9).
Table 4.3: Apportionment of Non-Point Source Pollution in the mining industry
SOURCE OF RISK AREAS OF POLLUTION POLLUTANTS FACTOR MINING TYPICAL SECTOR CONTAMINANTS Surface Ground Air water water
Gold Waste rock 1 √ √ √ sulphate, dumps metals (Al, As, Cr, Co, Sand dumps 2 √ √ √ Cu, Mn, Ni, Pb, Zn)
Slimes dams 3 √ √ √ cyanide
Evaporation 3 √ √ suspended solids dams sodium
chlorides
nitrogen compounds
acidity (often neutralised)
radio nuclides
salinity
dust
Coal Waste rock 1 √ √ √ sulfate dumps
acidity/HCO3 Sand dumps 2 √ √ √ metals (Fe, Mn, As, Slimes dams 3 √ √ √ Al, Co, Cu, Ni)
Evaporation 3 √ √ suspended solids dams sodium
chlorides
fluorides
dust
salinity
4.12 Non-Point Source Pollution Assessment
SOURCE OF RISK AREAS OF POLLUTION POLLUTANTS FACTOR MINING TYPICAL SECTOR CONTAMINANTS Surface Ground Air water water
Waste rock 1 √ √ √ sulphates dumps Platinum metals (from Tailings dams 3 √ √ associated sulfides, e.g. Co, Cu, Cr, Ni)
chlorides
sodium
salinity
dust
Smelters 3 √ oxides of sulphur
Diamonds Waste rock 1 √ √ √ sulphates dumps sodium Tailings residues 2 √ √ salinity Sediment 2 √ √ discharge turbidity
iron
aluminium
dust
Iron Waste dumps 2 √ √ √ acidity
Tailings dams 2 √ √ √ Hydrocarbons
Nitrogen compounds
dust
Manganese 2 √ √ √ Dust
Metals (Al, Cd, Mn, Zn, Cu)
Manganese oxides
Selenium
4.13 Non-Point Source Pollution Assessment
SOURCE OF RISK AREAS OF POLLUTION POLLUTANTS FACTOR MINING TYPICAL SECTOR CONTAMINANTS Surface Ground Air water water
Titanium 2 √ √ √ There is no significant water/environmental Stock pile pollution and no toxic leachates produced Tailings dam (see Appendix F on the enclosed CD). Effluent discharge
Chrome Waste rock In SA, chrome is mined alongside the Stock piles platinum group elements, thus the Tailings dams contaminants would be the same as for these products.
Platinum Stock pile √ √ √ Sulphur dioxide
Dust
Tailings dam √ √ √ CFCs
√ √ √ chlorides
Effluent sodium discharge salinity
dust
Sand 1 √ √ dust
Base metals Waste rock 1 √ √ √ sulfates
Stock piles 3 √ √ √ metals (As, Cd, Cr, Co, Cu, Fe, Pb, Mn, Tailings dams 2 √ √ Ni, Zn)
acidity
dust
Activities in the mining environment which pose a threat of groundwater contamination include the following:
Disposal of mining and mineral processing wastes (e.g. tailings, slimes, waste rock dumps
Mine wastewater ponds
Mine de-watering and mine drainage
4.14 Non-Point Source Pollution Assessment
Disposal of waste in unused or abandoned mines
Uncontrolled dumping
Disturbance or damage to aquifers by quarrying, opencast or underground mining
Activities which may result in the alteration of recharge (IGS, 2004).
Activities are specific for different types of mines and hence the pollution type and severity will vary depending on the activity and the type of mine. Mines also produce a variety of potential contaminants, depending on the ore deposit type, mining processes and mineral processing activities at specific sites (IGS, 2004).
By-products from gold mines, include uranium and acid/pyrite, which are potential sources of groundwater pollution and acid mine drainage. Coal mining’s impact on the water resources varies according to the life cycle of the mine and coal mines may produce large quantities of acid or saline mine drainage.
The associated environmental impacts are generally less severe with diamond mining and the potential for groundwater contamination lower than those in gold and coal tailings (IGS, 2004). However, it must be noted that alluvial diamond mining can destroy the natural grading of aquifers.
The magnitude of the threat from mining activities is dependent on whether precautionary measures are taken to prevent contamination, but in many cases, the scale of mining operations is such that groundwater pollution cannot be completely avoided (IGS, 2004).
Abandoned mines pose a potentially even larger threat to groundwater resources, since most were operated for decades without any environmental controls. Recorded polluting incidents from mines have occurred primarily in Gauteng and Mpumalanga Provinces, where gold and coal mines produce AMD, causing contamination of groundwater systems following infiltration (IGS, 2004).
Coal and gold mines, especially closed and abandoned mining operations, appear to be the most significant threats in terms of potential groundwater contamination from the mining sector in South Africa (IGS, 2004). Acid generation and decreasing groundwater pH has been noted in some gold and coal mining areas in South Africa, but in many cases, AMD is neutralised by reaction with the country rock to produce saline drainage instead (IGS, 2004).
Contamination of groundwater sources from contaminated surface water is possible where there is a direct connection between the resources. The connection to these surface water bodies, contributing to this type of groundwater contamination, can either be natural or man-made (IGS, 2004). Some examples of such interaction in South Africa with regards to mining are noted below:
Pumpage from mines into surface water. An example of this is the Stilfontein Gold Mine water which is pumped from Margaret shaft into the Koekemoerspruit (IGS, 2004). Pumping influences the flow, temperature, and hydrochemical interactions and consequent contaminant transport within this spruit. It was illustrated that in times of higher surface water flow and groundwater abstraction, flow reversals could occur. One of the major issues here is that the pumping of Margaret Shaft water costs several millions of Rand per month – who is responsible for these pumping costs?
Decant from coal and gold mines. Several of the gold mines on the West Rand (Gauteng) and coal mines in Mpumalanga Province will decant poor quality post-closure (IGS, 2004).
Localised salination of alluvial aquifers can occur adjacent to the Vaal River as a result from the high salt load contributed by effects from mining activities in the river.
4.15 Non-Point Source Pollution Assessment
Re-circulation of water from sources such as slimes dams, evaporation dams, etc. at the mines overlain by dolomite can lead to heightened salination and increase in the dissolution of subsurface dolomites and subsequent sinkhole formation (GIS, 2004).
4.7 Quantification of Non-Point Pollution from SA mining Industry
Based on literature (Appendix A-M on the enclosed CD) Non-Point sources and receptors of Non-Point source pollutants associated with the major mining sectors were identified (Table 4.3). Each receptor was given a risk factor as listed in Table 4.2.
Tables 4.4-4.8 summarises the typical contaminants associated with different mining commodities as well as the typical contaminants risk factor. The national prioritisation of contaminants table (IGS, 2004) was used as basis to categorise different contaminants in terms of risk factor (Tables 4.4-4.8). Thus Tables 4.4-4.8 were derived by:
Ranking contaminants between 1 and 4 according to the risk associated with the different contaminants (e.g. 1 = low to 4 = high risk)
Ranking the source of pollutants (based on the literature search, see deliverable 1) based on the risk involved between 1 and 3 where 1 is a low risk and 3 is a high risk.
A typical risk contaminants factor was then derived for each pollutant by multiplying the contaminant risk factor with the risk factor involved with each of the sources of pollution and adding the individual risk factor involved with each source of pollution, e.g.:
For aluminium:
Contaminant – Ranking for aluminium = 1
Source – Ranking for waste rock dump = 1, sand dumps = 2, slimes dams = 3, evaporation dams = 3 and smelting and processing = 3
Aluminium could potentially be present in all of the sources except the smelting and processing category thus:
Contaminant risk factor for aluminium =
(contaminant(Al) x source(waste rock dump) + contaminant(Al) x source(sand dumps) + contaminant(Al) x
source(slimes dams) + contaminant(Al) x source(evaporation dams) + contaminant(Al) x source(smelting and
processing)
Contaminant risk factor for aluminium =
(1x1) + (1x 2) + (1x3) + (1x3) + (0x3)
Contaminant risk factor for aluminium = 9
This was repeated for each of the contaminants and the total contaminant risk factor derived from the sum of the individual risk factors.
The total risk contaminant factor was then divided by the amount of contaminants positively identified for each mining commodity (details described in paragraph below) to determine a risk factor corrected for the amount of contaminants involved.
4.16 Non-Point Source Pollution Assessment
Detailed information is available on certain mining commodities whereas others only have limited information available. This could lead to mining commodities of which more details are available to have the highest risk factor in terms of contaminants. This is not to say that other mining commodities do not have as great a potential of pollution based on the risk factor associated with the contaminants, just because the information is not readily available. Therefore, the total risk factor associated with the different contaminants (Tables 4.4-4.8) was divided by the amount of contaminants identified (or of which information was available) to normalise the data.
4.17 Non-Point Source Pollution Assessment
Table 4.4: Typical contaminants risk factor associated with gold mining
WASTE EVAPORA- SMELTING TYPICAL SAND SLIMES ROCK TION / PROCES- CONTAMINANTS DUMPS DAMS DUMPS DAMS SING RISK FACTOR (RF) Ranking 1 2 3 3 3 Al 1 Yes Yes Yes Yes No 9 As 4 Yes Yes Yes Yes Yes 48 Cd 3 No No No No Yes 9 Co 2 Yes Yes Yes Yes No 18 Cr 4 Yes Yes Yes Yes Yes 48 Cu 2 Yes Yes Yes Yes Yes 24 Trace Fe 2 Yes Yes Yes Yes Yes 24 Metals Hg 3 No No No No Yes 9 Mn 2 Yes Yes Yes Yes No 18 Ni 2 Yes Yes Yes Yes Yes 24 Pb 3 Yes Yes Yes Yes Yes 36 Se 1 No No No No Yes 3 Sn 1 No No No No Yes 3 V 2 No No No No Yes 6 Zn 2 Yes Yes Yes Yes Yes 24 Salinity / Salinity 2 Yes Yes Yes Yes Yes 24 Acidity Acidity 4 Yes Yes Yes Yes No 36 Radio-nucleotides 4 Yes Yes Yes Yes No 36 Na 2 Yes Yes Yes Yes Yes 24 2- SO4 2 Yes Yes Yes Yes Yes 24 Other F 2 Yes Yes Yes Yes no 18 Organics Cl 1 Yes Yes Yes Yes Yes 12 Cyanide 4 Yes Yes Yes Yes Yes 48 Be 3 No No No No Yes 9 B 1 No No No No Yes 3 Hydrocarbon 2 Yes Yes Yes Yes No 18 Chlorinated 2 No No No No Yes 6 Organics solvents Nitrogen 2 Yes Yes Yes Yes No 18 Mineral Oils 2 No No No No Yes 6 Suspended 2 Yes Yes Yes Yes No 18 Other Solids Dust 2 Yes Yes No No Yes 12 53 106 153 153 150 Total contaminant risk factor 615 Risk factor corrected for amount of contaminants 19.84
4.18 Non-Point Source Pollution Assessment
Table 4.5: Typical contaminant risk factor associated with coal mining
WASTE TYPICAL SAND SLIMES EVAPORATION ROCK CONTAMINANTS DUMPS DAMS DAMS DUMPS RISK FACTOR (RF) Ranking 1 2 3 3 Al 1 Yes Yes Yes Yes 9 As 4 Yes Yes Yes Yes 36 Cd 3 No No No No 0 Co 2 Yes Yes Yes Yes 18 Cr 4 No No No No 0 Cu 2 Yes Yes Yes Yes 18 Trace Fe 2 Yes Yes Yes Yes 18 Metals Hg 3 No No No No 0 Mn 2 Yes Yes Yes Yes 18 Ni 2 Yes Yes Yes Yes 18 Pb 3 No No No No 0 Se 1 No No No No 0 Sn 1 No No No No 0 V 2 No No No No 0 Zn 2 No No No No 0 Salinity / Salinity 2 No No No No 0 Acidity Acidity 4 Yes Yes Yes Yes 36 Radio-nucleotides 4 No No No No 0 Na 2 Yes Yes Yes Yes 18 2- SO4 2 Yes Yes Yes Yes 18 Other F 2 No No No No 0 Organics Cl 1 Yes Yes Yes Yes 9 Cyanide 4 No No No No 0 Be 3 No No No No 0 B 1 No No No No 0 Hydrocarbon 2 Yes Yes Yes Yes 18 Chlorinated 2 No No No No 0 Organics solvents Nitrogen 2 No No No No 0 Mineral Oils 2 No No No No 0 Suspended 2 Yes Yes Yes Yes 18 Other Solids Dust 2 Yes Yes 6 30 60 84 Total contaminant risk factor 258 Risk factor corrected for amount of contaminants 18.43
4.19 Non-Point Source Pollution Assessment
Table 4.6: Typical contaminant risk factor associated with platinum mining
TYPICAL SMEL- CONTAMI- WASTE EVAPO- SAND TAILINGS SLIMES TING / NANTS ROCK RATION DUMPS DAMS DAMS PROCES RISK DUMPS DAMS -SING FACTOR (RF)
Ranking 1 2 3 3 3 3 Al 1 No No No No No No 0 As 4 No No No No No No 0 Cd 3 Yes No Yes No No Yes 0 Co 2 Yes No Yes No No Yes 14 Cr 4 Yes No Yes No No Yes 28 Cu 2 No No No No No No 14 Trace Fe 2 No No No No No No 0 Metals Hg 3 No No No No No No 0 Mn 2 Yes No Yes No No Yes 0 Ni 2 No No No No No No 14 Pb 3 No No No No No No 0 Se 1 No No No No No No 0 Sn 1 No No No No No No 0 V 2 No No No No No No 0 Zn 2 Yes No Yes No No Yes 14 Salinity / Salinity 2 No No No No No No 0 Acidity Acidity 4 No No No No No No 0 Radio-nucleotides 4 Yes No Yes No No Yes 14 Na 2 Yes No Yes No No Yes 14 2- SO4 2 Yes No Yes No No Yes 14 Other F 2 Yes No Yes No No Yes 7 Organics Cl 1 No No No No No No 0 Cyanide 4 No No No No No No 0 Be 3 No No No No No No 0 B 1 No No No No No No 0 Hydrocarbons 2 No No No No No No 0 Chlorinated 2 No No No No No No 0 Organics solvents Nitrogen 2 No No No No No No Mineral Oils 2 No No No No No No 0 Suspended 2 No No No No No No 0 Other Solids Dust 2 Yes No No No No Yes 8 53 57 63 Total contaminant risk factor 141 Risk Factor corrected for amount of contaminants 14.10
4.20 Non-Point Source Pollution Assessment
Table 4.7: Typical contaminant risk factor associated with diamond mining
SMEL- TYPICAL WASTE EVAPO- SEDIMENT SAND TAILINGS SLIMES TING / CONTAMI- ROCK RATION DIS- DUMPS DAMS DAMS PROCES- NANTS RISK DUMPS DAMS CHARGE SING FACTOR (RF)
Ran- 1 2 3 3 3 3 2 king Al 1 Yes No Yes No No No Yes 6 As 4 No No No No No No No 0 Cd 3 No No No No No No No 0 Co 2 No No No No No No No 0 Cr 4 No No No No No No No 0 Cu 2 No No No No No No No 0 Trace Fe 2 Yes No Yes No No No Yes 12 Metals Hg 3 No No No No No No No 0 Mn 2 No No No No No No No 0 Ni 2 No No No No No No No 0 Pb 3 No No No No No No No 0 Se 1 No No No No No No No 0 Sn 1 No No No No No No No 0 V 2 No No No No No No No 0 Zn 2 No No No No No No No 0 Salinity / Salinity 2 Yes No Yes No No No Yes 12 Acidity Acidity 4 No No No No No No No 0 Radio-nucleotides 4 No No No No 0 Na 2 Yes No Yes No No No Yes 12 2- SO4 2 Yes No Yes No No No Yes 12 Other F 2 No No No No No No No 0 Organics Cl 1 No No No No No No No 0 Cyanide 4 No No No No No No No 0 Be 3 No No No No No No No 0 B 1 No No No No No No No 0 Hydrocarbons 2 Yes No Yes No No No Yes 12 Chlorinated 2 No No No No No No No 0 Organics solvents Nitrogen 2 No No No No No No No 0 Mineral Oils 2 No No No No No No No 0 Suspended 2 No No No No No No No 0 Other Solids Dust 2 Yes No Yes No No Yes 12 13 39 26 Total contaminant risk factor 78 Risk Factor corrected for amount of contaminants 11.14
4.21 Non-Point Source Pollution Assessment
Table 4.8: Typical contaminant risk factor associated with base metal mining
TYPICAL WASTE EVAPO- SMELTING SAND TAILING SLIMES STOCK CONTAMI- ROCK RATION / PROCES- DUMPS S DAMS DAMS PILED NANTS RISK DUMPS DAMS SING FACTOR (RF)
Ran- 1 2 3 3 3 3 2 king Al 1 Yes No Yes No No Yes Yes 10 As 4 Yes No Yes No No Yes Yes 40 Cd 3 No No No No No No No 0 Co 2 Yes No Yes No No Yes Yes 20 Cr 4 Yes No Yes No No Yes Yes 40 Cu 2 Yes No Yes No No Yes Yes 20 Trace Fe 2 Yes No Yes No No Yes Yes 20 Metals Hg 3 Yes No Yes No No Yes Yes 30 Mn 2 Yes No Yes No No Yes Yes 20 Ni 2 Yes No Yes No No Yes Yes 20 Pb 3 Yes No Yes No No Yes Yes 30 Se 1 Yes No Yes No No Yes Yes 10 Sn 1 Yes No Yes No No Yes Yes 10 V 2 Yes No Yes No No Yes Yes 20 Zn 2 Yes No Yes No No Yes Yes 20 Salinity / Salinity 2 Yes No Yes No No Yes Yes 20 Acidity Acidity 4 No No No No No No No 0 Radio-nucleotides 4 No No No No No No No 0 Na 2 Yes No Yes No No Yes Yes 20 2- SO4 2 Yes No Yes No No Yes Yes 20 Other F 2 No No No No No No No 0 Organics Cl 1 Yes No Yes No No Yes Yes 10 Cyanide 4 Yes No Yes No No Yes Yes 40 Be 3 Yes No Yes No No Yes Yes 30 B 1 Yes No Yes No No Yes Yes 10 Hydrocarbons 2 No No No No No No No 0 Chlorinated 2 Yes No Yes No No Yes Yes 20 Organics solvents Nitrogen 2 Yes No Yes No No Yes Yes 20 Mineral Oils 2 Yes No Yes No No Yes Yes 20 Suspended 2 No No No No No No No 0 Other Solids Dust 2 Yes No Yes No No Yes Yes 20 54 162 162 162 Total contaminant risk factor 540 Risk Factor corrected for amount of contaminants 21.60
4.22 Non-Point Source Pollution Assessment
Table 4.9 summarises the risk factor associated with the run of mill/ore milled per mining commodity expressed as a percentage of the total run of mill.
Table 4.9: Run of mill/ore milled risk factor allocated to each mining commodity
MINING RUN OF MILL/ORE RUN OF MILL/ORE MILLED RISK COMMODITY MILLED (2000-2004) FACTOR
Gold 612,157,775 23
Coal 1,461,786,485 55
Platinum 321,484,513 12
Diamonds 169,065,000 6
Chrome 39,102,521 1.5
Manganese 26,444,686 1
Zinc 11,832,694 0.5
Table 4.10 lists the total risk factor associated with the different mining commodities.
Table 4.10: Total risk factor associated with the different mining commodities
RUN OF MILL/ORE TYPICAL MINING COMMODITY MILLED RISK CONTAMINANTS TOTAL RISK FACTOR FACTOR RISK FACTOR
Gold 23 19.84 456
Coal 55 18.43 1014
Platinum 12 14.10 169
Diamonds 6 11.14 67
Chrome 1.5 21.60 32
Manganese 1 21.60 22
Zinc 0.5 21.60 11
Gold and coal mining were identified as the mining commodities having the highest potential to contribute to Non-Point Source Pollution (Figure 4.1). This could mainly be attributed to the magnitude at which gold and coal are currently and was historically mined. Although the base metals have a wider range with regards to the type of contaminants produced, the scale of production lowers the risk of contributing to Non-Point Source Pollution.
4.23 Non-Point Source Pollution Assessment
1200
1000
800
600 Total risk factor
400
200
0 Gold Coal Platinum Diamonds Chrome Manganese Zinc
Figure 4.1: Total risk factor allocated to the different mining sectors
Unfortunately, due to the lack of detailed information, the following factors could not been incorporated into this risk assessment:
The differentiation between the impact of the different receptors (e.g. waste rock dumps) between the different mining commodities.
The age of the receptors. Age plays a major role on the impact as older mining activities did not include good housekeeping and pollution control measures were not put in place. The chemical characterisation of waste receptors also changes over time. A WRC project is currently being finalised to determine if the age and characteristics of tailings dams make a difference to the runoff potential and hence their pollution contribution.
The role of gas emissions from the different mining commodities.
4.8 Waste Discharge Charge System (WDCS)
Another component, which needs to be incorporated into the risk assessment, is the waste discharge charge system (WDCS) as is currently being developed by DWAF. This will however only be possible if more detailed information on the different waste type facilities is obtained from the different mines.
The development of a WDCS in South Africa has been proposed to promote waste reduction and water conservation (Von der Heyden et al., 2005). The WDCS is based on the polluter-pays principle and is designed such that the management of waste discharges achieves resource quality objectives (RQOs) at the minimum total cost to the catchment. Two charges are distinguished: i) a charge for optimising use of the resource (Incentive Charge) and
4.24 Non-Point Source Pollution Assessment ii) a charge for development and operation of mitigation measures in the resource (Mitigation Charge) (Von der Heyden et al., 2005).
The WDCS will be applied to both point sources and Non-Point Source (NPS) contamination. In the inclusion of NPS, the charge system distinguishes between authorised and non-authorised NPS, with the charge applied to the former group only, in the first instance.
The incorporation of NPS into the WDCS requires that the load of contaminants entering the resource be quantified (Von der Heyden et al., 2005). In addition, the Incentive Charge requires the calculation of the cost of reducing discharge load from the NPS through various technical, operational or management interventions. Once these data are available, the NPS are incorporated into the WDCS as per the point sources, with a common methodology for charge calculation.
Figure 4.2 shows the approach followed in estimating NPS discharge. It is recognised that two pathways exist through which NPS pollution enters the resource: – i) overland run-off and ii) subsurface seepage.
In calculating the discharge estimated from each type of authorised NPS, the WDCS deploys the equation articulated in the diagram (the sum of surface run-off and sub-surface flow) (Von der Heyden et al., 2005). In using this approach, the WDCS assumes that surface run-off only occurs under poor management conditions, and therefore surface run-off was imputed as zero for facilities meeting the standard requirements (Von der Heyden et al., 2005).
Calculating the NPS load to the resource
Load = A (tons)
Facility receiving effluent or waste Run-off = X (%)
Seepage = Y (%)
Discharges to surface water resources = W (%) Surface water resource (SWR)
Movement into the deep aquifer = Z (%) NPS load to SWR =
(A x X%) + (A x (Y x W)%)
Figure 4.2: Schematic showing approach to estimating NPS discharge to the surface water resource (Von der Heyden et al., 2005)
The WDCS estimates groundwater seepage based on the amount of seepage from the facility (Y), and the amount of this seepage that discharge to the surface water resource (W). The seepage from the facility that enters the deep aquifer (Z) is allocated a zero charge in the current version of the WDCS, as it does not discharge to the surface water resource (Von der Heyden et al., 2005). This might be true for this model but we know from experiences in the Central and Western Witwatersrand Basins that mine 4.25 Non-Point Source Pollution Assessment water pollution that enters the deep aquifer can become a problem and eventually end up decanting into the surface water many miles from the original source. The million rand question is who takes responsibility for the treatment and management of this decant water?
Seepage from the facility(Y) is dependent on the type of facility and the design, construction, management and maintenance of the facility. Therefore, there is significant variation in the extent of seepage from the various facilities. This is one of the major challengers that will need to be addressed in this project as it will differ from minerals mined, type of mining, age of deposit, locality of waste deposit, manner of deposition, etc.
Regarding seepage from a facility that enters the surface water resource (W), there was a marked difference in the sectors’ estimation of the proportion of groundwater that discharge to the resource (Von der Heyden et al., 2005). The range in estimates (15-70%) is driven by geology, with seepage predominantly moving into the deep aquifer over porous geology (e.g. dolomite) while over crystalline geology (e.g. granite) most seepage would follow shallow sub-surface pathways and discharge rapidly into the surface water resource (Von der Heyden et al., 2005). These estimates will need to be presented to the mining industry and some scientific evidence attached to them before they are accepted.
The Department of Water Affairs and Forestry (DWAF) convened sector task-teams to initiate the process whereby the water quality impact of various NPSs are quantified. The first step in this process was to develop generic estimates of the proportion of load applied to a facility that enters the resource as NPS. Three groupings of management practice are described – BATZI, standard practice and poor practice. (It is acknowledged that these estimates may be refined before formal inclusion in the WDCS).
4.9 Case studies of Potential Non-Point Mining Impacts
In order to attempt to apportion the contribution of Non-Point pollution to the surface and ground waters it is suggested that prior in depth catchment studies be used that have apportioned the Non-Point Source Pollution on a catchment basis. It is suggested that the following studies be used:
Gold
Vaal River Barrage Gold mining impacts (case study 1)
Lower Vet River (case study 2)
Schoonspruit and Koekemoerspruit catchment management strategy (case study 3 )
Coal
Development of an Integrated Water Resource model of the upper Olifants catchment (Base conditions) DWAF 1999 report No.: PB 100/00/0598. This model has some 15 coal mines as well as 5 power generation plants incorporated into its data base (case study 4)
Platinum
Case studies on the platinum mining industry. See case study 5.
Further discussions were held with Mr William Pulles, Mr Trevor Coleman and Dr Chris Herold with regards to available Non-Point water quality data originating from mines. These discussions concurred with the approach suggested by the representatives of the mining industry.
4.26 Non-Point Source Pollution Assessment
The above studies will enable us to apportion a typical Non-Point pollution load to rivers from gold and coal mines. The water and salt balances as well as models calibrated for these catchments will be used for this apportionment. Using expert knowledge the findings of these studies will be used to make assumptions for the rest of the country and possibly for the other major commodities mined in South Africa.
4.9.1 Gold: Case Study 1: Vaal Barrage Catchment
4.9.1.1 Background
The Vaal Barrage Catchment lies between the Vaal Dam and the Vaal Barrage. While the Catchment relies heavily on return flows from domestic and industrial users, it is uniquely characterised by a large number of gold mines (more than 60) situated in a band running south of Johannesburg from Randfontein Gold estates gold mine in the west through to Nigel in the east. These mines have an impact both as point source and non-pint source polluters of this Catchment. A study was undertaken by Pulles Howard and de Lange in 1995 on behalf of the Department of Water Affairs and Forestry (DWAF) on the preliminary situational analysis of this Catchment in order to develop a practical water quality management plan to address problems relating to the gold mines in the Catchment. A report from this study served as reference to this case study (DWAF, 1995).
This study undertook to evaluate the data available on the preliminary situational analysis report in order to:
Quantify Non-Point pollution from these mines into the catchment with respect to:
Salt balance and
Water balance
The Vaal Barrage catchment has five sub-catchments namely:
Blesbok/ Suikerbosrand
Klipriver/ Natalspruit/ Rietspruit
Upper Taaibos
Groot Rietspruit
Vaal river system
Gold mines in the catchment (DWAF, 1995):
Mpumalanga: 36 mines many are inactive and lie between Gravelotte and Barberton.
Evander goldfield: 4 active mines draining to waterval situated upstream of the Vaal dam.
East central and West Witwatersrand from Heidelberg to Randfontein: 6 active mines, tailings reprocessing operations draining to the Vaal.
West rand: 13 Gold mines situated in a dolomitic area draining to the Vaal via the Mooi River.
4.27 Non-Point Source Pollution Assessment
4.9.1.2 Pollution (DWAF, 1995):
The underground water is mainly affected by sulphur (1 to 9% Sulphur) as pyrite FeS2 and arsenopyrite. These contribute to sulphuric acid formation resulting in corrosion and blockages of pipes.
The tailings and slimes dams are permeable allowing for the oxidation of pyrite resulting in up to 25% sulphuric acid and ferric sulphate leachate.
It is estimated that mining activities contributes between 40 and 60% of the Non-Point salt load, thus the total contribution of mining to Catchment salt load will be in the order of 30 to 45%.Although the figure of 40-60% is arbitrary, it is not unreasonable as there is a lot of mining activity which collectively contribute 291 993 t/a or 735 of the total Non-Point salt load in the Catchment. The arbitrary figure was reached from considering removal of all (point source and Non-Point) mining activities in the Catchment which, resulted in a 60% increase in in-stream water quality.
With the gold mines being are responsible for 8% of volume of point source discharge and 34% of salt load, the estimated Non-Point pollution associated with the gold mines from the tailings and slimes dams, sand dumps and waste rock dumps comes to 12 to 15%. However this has not been accurately quantified as there is no data on polluters and individual pollution loads. The complexity of land ownership further exacerbates the problem.
Data collection from the different mines is summarised as follows: (DWAF, 1995):
DRD (now Simmer and Jack): There is monthly monitoring of water quality and therefore good information on surface water. There is little information on ground water and the slimes dams are not monitored.
Marievale: Dry mine, no pumping therefore the only source of Non-Point pollution results from runoff from the slimes dams and surface. However, there are toe paddocks on the slimes dams.
Primrose: There is no water quality monitoring, no information on surface water. There is a water balance model and there are toe paddocks on the slimes dams.
Grootvlei: There is monthly water quality data upstream, downstream and at Marievale. There are slimes dams with toe paddocks collecting runoff from the slimes dams. There might be possible groundwater seepage from the slimes dams.
ERPM: There is water quality analysis, the slimes dams have toe paddocks and top perimeter walls thus no surface runoff is expected.
RM3: There is good water quality data and a water balance model. The slimes dams have toe paddocks and perimeter walls.
Doornkop: There is no routine analysis but a water balance report exists. The groundwater quality monitoring for seepage from the slimes dams is carried out at a number of boreholes. There is a small runoff expected from the pan between Doornkop slimes dam and South Roodepoort.
EGO: There is a groundwater monitoring system at a number of boreholes around the tailings dams. Water quality is monitored upstream and downstream the tailings dams as well as a Marievale bird sanctuary. There is no information on surface runoff and possible pipe blockages might lead to spillage from the slimes dams.
4.28 Non-Point Source Pollution Assessment
Kloof: There is monitoring of water quality of the effluent discharged into the Leeuspruit. Groundwater quality is monitored at boreholes but there is no water balance model and lack of information on the slimes dams.
WAGM: There are 7 monitoring sites but no information on the slimes dams and no water balance.
Benoni Gold: There are six monitoring points, no water balance information on slimes dams.
Rand leases: There are 10 sampling site but no information on slimes dams and no water balance.
Knights: There is quarterly water quality analysis on tailings dams using boreholes, return and transfer water on a stream around the dam. No water balance and a couple of the slimes dams are not monitored.
The water and salt balance between 1991 and 1992 are indicated in Figures 4.3 and 4.4.
Figure 4.3: The water balance between 1991 and 1992 in the Vaal Barrage catchment.
Figure 4.4: Salt balance between 1991 and 1992 in the Vaal Barrage catchment
4.9.1.3 Results:
Table 4.11 and Table 4.12 indicate the water and salt balance for the Vaal Barrage (DWAF 1995).
4.29 Non-Point Source Pollution Assessment
Table 4.11: A summary of the water balance in the Vaal Barrage catchment (DWAF, 1995).
Vaal Barrage catchment
Total Point source Non-Point/Agric Runoff
Blesbokspruit
94577 33737 0 60840
% of total 35.7 0 64.3
Non-Point @13% 0
Suikerbosrand
11401 0 0 11401
% of total 0 0 100
Non-Point @13% 0
Klipriver
200688 126908 0 73780
% of total 63.2 0 36.8
Non-Point @13% 0
Natalspruit
143854 54084 36844 0
% of total 37.6 25.6 0
Non-Point @ 13% 4789
Rietspruit
47390 0 0 47390
% of total 0 0 100
Non-Point @ 13% 0
Taaibosspruit
71290 0 0 71290
% of total 0 0 100
Non-Point @ 13% 0
Groot Rietspruit
38303 35913 0 2390
% of total 93.8 0 6.24
4.30 Non-Point Source Pollution Assessment
Vaal Barrage catchment
Total Point source Non-Point/Agric Runoff
Non-Point @ 13% 0
Vaal River system
816557 4528 0 812029
% of total 0.55 0 99.5
Non-Point @ 13% 0
Table 4.12: Summary of the salt balance of the Vaal Barrage catchment (DWAF, 1995).
Vaal Barrage catchment
Total Point source Non-Point/Agric Runoff
Blesbokspruit
91961 25092 55098 11771
% of total 27.29 59.91 12.80
Non-Point load @13% 7162
Suikerbosrand
1778 0 0 1778
% of total 0.00 0 100
Non-Point load @13% 0
Klipriver
122949 69540 39465 13944
% of total 56.6 32.1 11.4
Non-Point load @13% 5130
Natalspruit
107699 52941 36844 17914
% of total 49.2 34.2 16.6
Non-Point load @13% 4789
Rietspruit
13804 0 4722 9082
4.31 Non-Point Source Pollution Assessment
Vaal Barrage catchment
Total Point source Non-Point/Agric Runoff
% of total 0 34.2 65.8
Non-Point load @13% 61386
Taaibosspruit
11620 0 0 11620
% of total 0 0 100
Non-Point load @13% 0
Groot Rietspruit
27684 28262 -968 390
% of total 102.1 Added 1.41
Non-Point load @13% 0
Vaal River System
275718 2220 39174 234324
% of total 0.81 14.2 84.9
Non-Point load @13% 5092
From this study the contribution from the gold mining industry to the surface water salt load was estimated to be 13%.
4.9.2 Case Study 2: Lower Vet River Catchment
4.9.2.1 Introduction:
A study was conducted in 1992 for the Department of Water Affairs and Forestry (DWAF,) investigated the development of the Lower Vet River Catchment Water Management Strategy (DWAF, 1992). The study area comprised of the Sand River sub-Catchment which, transverses the Free State Goldfields region as well as Lower Vet River Catchment. Key balance contaminants measured were salt and flow/ water balance.
The lower vet river study was divided in to the following sub-catchments:
Doring River/ Theronspruit system
Bosluisspruit/ Doring River system
Sand River – upstream of the Sand River canal
Sand River canal
Sand River – downstream of the Sand River canal
4.32 Non-Point Source Pollution Assessment
Due to lack a central database data was collected from 11 sources including the different mines, DWAF and local authorities. There was a further four site visits by the team where water quality (pH and EC) and flow of the rivers and streams was measured. Effluent samples were collected from different sites including mines, industry, irrigation return flow canals, slimes dams, rock dumps, evaporation pans, return water dams and solid waste disposal sites and the water measured the water level of dams.
4.9.2.2 Mining activities:
Free gold: 6 mines (President Brand, President Steyn, FS Geduld, Freddies, Saaiplaas and Western Holdings).
Gen gold: 4 mines (Orynx, St Helena, Unisel and Beatrix).
JCI: 1 mine (HG Joel)
Randgold: 2 mines (Harmony and Harmony freegold)
4.9.2.3 Data status:
There was no groundwater data, inadequate surface water flow data but a flow and contaminant water balance was available. Thus the team utilised the available data and that of the site visits to extrapolate their findings. Although each mine had its own data there was lack of accuracy as the different mines used different methods.
4.9.2.4 Flow balance:
Since the rivers were dry, the transport system for Non-Point contaminants seemed to be provided b the discharged sewage treatment works effluent. The flow balance in this study was assumed to be relative contributions of the individual streams, rivers and point sources.
4.9.2.5 Non-Point pollution:
Non-Point pollution is expected at Doring/ Theronspruit due to the surrounding mines and at Bosluisspruit / Doring River.
No Non-Point pollution expected at Sand River canal.
4.9.2.6 Non-Point flow:
Beatrix dams: = 0.09 ML.d-1
Joel dams: = 0.02 ML.d-1
Convent dams (spillage seldom): = 0.11 ML.d-1
4.9.2.7 Salt balance:
Since there is no flow data it was difficult to quantify Non-Point salt load as there is no means of transport for it. Thus the calculated values might be an underestimation of the real scenario.
The total salt load (Non-Point and point source) into the surface system = 48 559 Kg.d-1
Total mine related Non-Point pollution = 13 875 Kg.d-1
4.33 Non-Point Source Pollution Assessment
Thus the mine related Non-Point pollution accounts for 57% of the total Non-Point pollution (DWAF, 1996).
4.9.2.8 Sulphate balance:
Since average data was used, it is not expected to balance. The major contributor of sulphate is point source. Sulphate load apportionment and the subsequent extrapolation to other seasonal conditions were complicated by the poor relationship between Electrical Conductivity and sulphate data.
4.9.2.9 Water balance:
A total of 220 618 m3d-1 mine water is disposed off in various evaporation areas daily from an average daily supply of 341 939 m3d-1.Thus the total water balance needs to account for the evaporation losses from slimes dams, dams and evaporation ponds.
4.9.3 Case Study 3: Koekemoerspruit (Middle Vaal)
4.9.3.1 Background
This case study deals with the water and salt balance for the Koekemoerspruit catchments. The water quality and flows for the Koekemoerspruit catchments are dealt with in the Catchment Management Strategy (DWAF 2006a).
Margaret Shaft water from DRD mine has in the past had a major influence on water and salt balance in the Koekemoerspruit. This influence has been reduced due to the Margaret Shaft water being re-routed to Mine Waste Solutions (MWS).
Within the constraints of the available data as adequate as possible water and salt balance for the study area will be established by:
Establishing an understanding of the interaction between groundwater and surface water. Decanting into surface waters as well as groundwater contributions to base flow will be required.
Quantifying the contribution of various pollution sources / discharges. During a previous study the main pollution sources were identified as:
- Mining pollution (point decants, especially into the Koekemoerspruit, and Non-Point Source Pollution from the various mines and their slimes dams). - Treated sewage effluent (from the various sewage works in the area). - Urban runoff (mainly from Stilfontein). - Irrigation return-flow (from lands irrigated with mine water and from riparian irrigation farmers).
The determination of the water and salt balance addressed the following criteria:
Quantifying volumes of ground water abstraction from and surface water recharge/leaching towards the ground water regime
Determining flow patterns within the area.
Assessing the quality of each component and calculating the salt load of each component.
4.34 Non-Point Source Pollution Assessment
The study area exhibits certain regions where there is pronounced interaction between surface and groundwater. Areas that need to be focused on include:
Pumpage from mines into surface water. The most pronounced of these is probably the Stilfontein mine water, which is pumped from Margaret shaft into the Koekemoerspruit and more recently to Mine Wastes Solutions (WMS).
Re-circulation of water in the mines overlain by dolomite.
Eye flows. This includes the contribution of the eyes, which emanate in the KOSH area adjacent to the Vaal River.
Seepages into the streams.
4.9.3.2 Methods
The DWAF (2002 and 2006) studies in the Klerksdorp-Orkney-Stilfontein-Hartebeesfontein (KOSH) area provided valuable input into the water and salt balance. Dewatering of the mines is an important influence on the geohydrological regime.
A wet period and a dry period will be used as examples for both the flow and load calculations.
The study area exhibits certain regions where there is pronounced interaction between surface and groundwater. Areas that need to be focused on include:
Pumpage from mines into surface water. The most pronounced of these is probably the Stilfontein mine water, which is pumped from Margaret shaft into the Koekemoerspruit and more recently to Mine Wastes Solutions (WMS).
Re-circulation of water in the mines overlain by dolomite.
The limitations of the water balance relate to limitations in the database. The inflows and outflows for each calculation point are listed in
Table 4.13: Inflows and outflows listed for each calculation point in the water balance
UNKNOWNS TO BE AREA INFLOWS OUTFLOWS CALCULATED
Vaal upstream of Schoemansdrift (C2H018) Sum of inflows - Koekemoerspruit Mooi River (C5H085)
Koekemoerspruit Stilfontein WWTW Buffelsfontein weir Losses to underground (C2H139) Buffelsfontein WWTW Mine Waste Solutions Excess of Margaret Shaft pumping
Vaal @ Upper Vaal Abstraction by Midvaal Inflow from Vierfontein water company Spruit Pilgrims Estate Koekemoerspruit Anglo abstracts Midvaal WWTW
4.35 Non-Point Source Pollution Assessment
UNKNOWNS TO BE AREA INFLOWS OUTFLOWS CALCULATED
Pilgrim's Estate weir (C2H007)
The following components were considered for the surface water balance: (as indicated in Figures 4.5 and 4.6).
IN:
Flows from upstream
Additional inflows from known sources
Surface runoff (rainfall)
OUT:
Losses to downstream
Evaporation from rivers
Abstractions
Unknown abstractions
The following assumptions were made in the water/salt balance:
Losses and gains from rivers to groundwater shall be quantified by the groundwater study, but were ignored at this stage.
Evaporation losses occur from rivers only and rivers contribute to 5% of the catchment surface area.
TDS concentration of surface runoff is 200 mg/ℓ.
TDS concentration of evaporated water is zero.
Irrigation return flows and loads were assumed to be 10% of the irrigation water.
Rainfall was included as surface runoff, but direct rainfall on the rivers was ignored.
Surface runoff and evaporation values were obtained from Midgley et al. (1994). The surface runoff depth ranges from 5 to 10 mm/yr and the evaporation ranges between 1600 and 2000 mm/yr.
Mining Waste Solutions (MWS) will not use more than 400 Mℓ of water a month that is currently pumped from the Margaret Shaft as process water to Chemwes.
No flow data for the Stilfontein WWTW was available for the month of June 2002. Thus the average monthly flow for the dry period April-September 2002 was calculated over five months.
4.36 Non-Point Source Pollution Assessment
EYE Ventersdorp MONITORING POINTS
V.dorp WWTW Ri etsprui t DWAF HO flow & quality Taaibosspruit MWS DWAF HO quality only
Other Excess from Irrigation Buisfontein Margaret Shaf t spruit SC HO pumping ON SP Stilfontein Mine RUI
T New Machvi e Mi ne Stilfontein
DAM Stilf . WWTW Khuma KOEKEMOERSPRUIT Klerksdorp
K.dorp WWTW Hartbeesfontein WWTW Buffelsfontein 7Ml/d Mi ne Buffelsfontein Mi ne Buffels . WWTW AngloGold JAGSPRUIT
Orkney Mooi Ri ver Ysterspruit MIDVAAL Orkney WWTW
VAAL RIVER
Vierfonteinspruit
Figure 4.5: Diagram to illustrate all the inflows and outflows of the catchment river system
4.9.3.3 Groundwater Component
An overview of new data obtained from sources is as follows (DWAF 2006):
AngloGold Ashanti Vaal River Operations
Has an extensive groundwater monitoring network for the AngloGold Ashanti Vaal River Operations. All data from 2001 has been added to the WISH data base:
113 sites with data attached.
98 have some chemistry data of which more than 5 records, 81 have water levels, 70 have more than 3 water level records and 58 have more than 5 water level records.
Data dates up to May 2005.
Simmer and Jack Mine Limited (formerly DRD)
4.37 Non-Point Source Pollution Assessment
Has a groundwater monitoring network for the Simmer and Jack Mine, Buffelsfontein Gold Mine. All data from November 2001 has been added to the existing data base that has:
17 sites with co-ordinates.
14 sites with some chemistry data.
15 sites with water levels.
4 new sites for which there are chemistry data and 15 sites with water levels (no co-ordinates available).
IN OUT
Inflows from upstream
Surface runoff Losses to downstream
Rainfall Evaporation SURFACE WATER RESOURCE Point and diffuse Abstraction effluents
Eye seepage Bedloss from streams
INTERACTION
Bedloss from streams Eye seepage
Recharge GROUNDWATER RESOURCE Abstraction Point and diffuse effluents Evapotranspiration
Figure 4.6: Water balance components to be considered for a complete water balance study
4.9.3.4 Results of water balance
Using the method described above, the water balance is calculated for each sub-catchment separately. This has been done for a wet period (Oct 2001 to Mar 2002) and a dry period (April-Sep 2002). In all cases mean values for the period were used. For some of the inputs a general value has been used, since specific data for the relevant time period was not available. All these uncertain values are very small compared to the other flows and therefore the error introduced in this way is considered negligible.
The flows in the Koekemoerspruit are compared in Figures 4.7 to 4.8 to indicate the following:
During the winter months (April 2002 to September 2002) the flows recorded (average daily) indicated that the flow released to the Koekemoerspruit from the Margaret Shaft was 20% higher than that recorded at the C2H139 weir. This could be as a result of the weir’s inaccuracies or due to river bed losses (Figure 4.7)
During the winter months (April 2003 to September 2003) the average daily flows for the C2H139 weir was very similar to the releases from the Margaret Shaft. This indicates that there are not river bed losses or that the weir reading is adequate. 4.38 Non-Point Source Pollution Assessment
During the wet months (Oct to March) the general trend is that the flows recorded at the C2H139 weir in the Koekemoerspruit are higher than the volumes of water released from Margaret Shaft
The flows in the Koekemoerspruit have changed as result of the reallocation of the Margaret Shaft water to MWS (Figure 4.8). Since April 2003 the volumes allocated to MWS have increased with a resultant reduction in the volumes pumped to the Koekemoerspruit as well as a reduced flow recorded at the C2H139 weir (Figure 4.8). The load from the Koekemoerspruit to the Vaal River will be reduced accordingly.
Figure 4.7: Comparison of the contribution of Margaret Shaft to the flow at the C2H139 Weir in the Koekemoerspruit during the 2002 and 2003 winter months
Figure 4.8: Comparison of the contribution of Margaret Shaft to the flow at the C2H139 Weir in the Koekemoerspruit during the 2001/2, 2002/3 and 2003/4 summer months
4.39 Non-Point Source Pollution Assessment
Figure 4.9: Mean average volumes of underground water from DRD, volume of water directed to MWS, volume of water discharged from Margaret Shaft to the Koekemoerspruit and the volume of water measures at the C2H139 weir in the Koekemoerspruit.
The current pumping of 400 ML of the available groundwater from Margaret shaft to new operations at MWS were included in the water balance for the dry period April-Sept 2002, since it is the period for which such a flow reduction would have the greatest impact on return flows to the Koekemoerspruit catchment.
According to Stilfontein Mine water use records obtained from DRD (now Simmer and Jack), only 57 ML of water is then still available for discharge into the Koekemoerspruit. According to DRD, MWS might even exceed the current abstraction volume, with the result that no water will be discharged into the Koekemoerspruit from Margaret Shaft (as indicated in Figure 6).
The pumping of 35% of the available groundwater from Margaret shaft to new operations at Mine Waste Solutions was calculated for a dry period (Table 4.12). The impact on the reduction in TDS load values were investigated indicating that a 35% flow reduction from the Margaret shaft will also yield a 35% reduction in TDS load (from 406 tons/month to 264 tons/month). The impact of the quantity of TDS on the Koekemoerspruit inflow into the Vaal River will be from 1139 tons/month to 996.2 tons/month.
4.40 Non-Point Source Pollution Assessment
Table 4.14: Summary of Margaret Shaft influence regarding flow (ML/month) and TDS values (tons/month) for wet and dry periods
FLOW: TDS: FLOW: TDS: Margaret Margaret Koekemoerspruit Koekemoerspruit Shaft Shaft into Vaal into Vaal (ML/month) (Tons/month) (ML/month) (Tons/month)
Wet period (10/01-03/02) 1019 367 1277 1656
Dry Period with 100% 1137 406 759 915 Margaret Shaft contribution (04/02-09/02)
Dry Period with 35% 400 143 359 996.2 Margaret Shaft contribution towards MWS (04/02-09/02)
From this study in the Koekemoerspruit the Non-Point source contribution to the salt load was estimated to range from 24 to 31% in the winter months and from 49 to 52% in the summer months.
4.9.4 Case Study 4: Upper Olifants River (Loskop Dam) Catchment
4.9.4.1 Introduction
As a result of the extensive coal mining activity in the Upper Olifants River catchment the water quality situation has deteriorated to such an extent that certain users in the catchment have found it necessary to use alternative sources of water. This led to the commissioning of various water quality studies by the Department of Water Affairs and Forestry to develop water quality management plans for selected areas of the Olifants River catchment (Calibration report, 2002). During these studies the WITSIM model was developed to simulate the production and conveyance of pollutant in the form of sulphates from the various mining related activities in the catchments (Calibration report, 2002).
4.9.4.2 Purpose of the Study
The purpose of the study is to compile an integrated water quality and quantity management model that can be used for the development and operational planning of the catchment. The model will be designed to simulate possible development and management options and future activities planned within the study area.
4.9.4.3 Description of the Study Area
The Upper Olifants River catchment comprises the drainage areas of the Olifants River, Klein Olifants River and Wilge River with tributaries down to the Loskop Dam. The headwaters of these rivers are located along the Highveld Ridge in the Secunda-Bethal area and the rivers then flow in a northerly direction towards Loskop Dam. The total catchment area is 12 285 km
The natural rivers and streams have been extensively dammed with the result the stream flow is now highly regulated. The major impoundments upstream of Loskop Dam include Witbank Dam, Middelburg Dam, Bronkhorstspruit Dam and Premiere Mine Dam. Many smaller farm dams and water supply structures associated with the mining operations have also been constructed in the catchment.
4.41 Non-Point Source Pollution Assessment
Several larger metropolitan areas and towns are located in the catchment. The Witbank and Middelburg metropolitan industrial corridor forms the major urban development. Several other towns and residential settlements include Bronkhorstspruit, Kriel, Hendrina, Kinross and Trichardt. Satellite townships are also associated with most of the mining operations and power stations.
Extensive coal mining takes place in the catchment, most of which occurs in the Witbank Coalfields and Highveld Coalfields. The landscape in the southern and central part of the catchment is dominated by mining operations and mining-related infrastructure. Coal mining is mainly conducted by opencast techniques, high extraction underground operations and conventional bord-and-pillar underground operations. The coal mines provide essential fuel to the local power stations as well as to the domestic and international markets. Numerous abandoned mining operations are located in the central part of the catchment, mainly towards the west and north-west of Witbank.
Several large coal-fired power stations are also located in the catchment including Arnot, Hendrina, Komati, Duhva, Matla, Kriel and Kendal. These stations are all supplied from local feeder mines in the catchment. Cooling water for the power stations has to be imported across several watersheds from other catchments where excess high quality water is available. Large ash disposal operations are associated with each power station.
Agriculture, both dryland and irrigated, is another important land use in the catchment with many areas in the southern and central portions producing high yields of maize. Irrigation farming of diverse crops takes place in various parts of the catchment the largest of which is the Loskop Dam Irrigation Scheme. Intensive farming in the form of piggeries and cattle feed lots are also scattered throughout the catchment.
The Upper Olifants River basin water resources are under constant pressure from both a supply/demand perspective as well as from a water quality perspective.
4.9.4.4 Water quality database
The main source of water quality data that was used to calibrate the model was obtained from the Department of Water Affairs and Forestry databases. This data was supplemented by data made available from the mines, industries and local authorities. The data from the mines was generally from a database of information used for compliance monitoring and did not include flow information. The grab samples are often collected on a monthly basis. This data was used to serve as a check on the calibration.
The water quality and flow data collected by the Department was used to produce a time series of monthly averaged sulphate concentration for calibration of the model. The time period used for the calibration of the model was from 1986 to 1996. This period was chosen as there is a sufficient number of grab samples of water quality data available to produce reasonably accurate monthly average sulphate concentrations.
4.9.4.5 Manipulation of water quality data
The approach used in creating the time series of monthly average sulphate concentrations is described below :
At many of the stations there were more frequent readings of electrical conductivity (EC) than sulphate concentrations. Regression relationships were developed between EC and sulphate concentration. The measured EC was then used to estimate sulphate concentrations;
Once the sulphate concentrations had been filled in using the EC, a regression analysis between the average daily flow rate and the sulphate load was undertaken. Due to the non-stationarity of the 4.42 Non-Point Source Pollution Assessment
sulphate concentration at many of the gauges, a moving regression analysis had to be undertaken. The results of the regression analysis were then used together with the daily flow record to fill in the missing sulphate concentrations at the gauges;
The total sulphate load was then calculated for each month and the measured monthly runoff volume was used to generate an average sulphate concentration for the month.
4.9.4.6 Atmospheric deposition used in calibrating model
The salt washoff module of the WQT model is driven by the build up of sulphate on the catchment surfaces and in the soils. The model input parameter is a monthly unit build-up rate (t/km2) for each catchment represented as a salt washoff module.
Given that 8 coal fired power stations have been active in the Loskop Dam catchment, the contribution of atmospheric deposition to the sulphate build-up rate is significant in this catchment. The accurate determination of this input is difficult as there are a number of sources, which contribute to the build up rate. Atmospheric deposition is one of the sources. Herold and Görgens (1991) and Herold et al. (1997) found by applying a catchment model, that atmospheric deposition and in particular power station emissions will have a significant impact on the water quality in the Vaal River catchment in the long term.
Coal fired power stations are a significant contributor to the sulphate mass on the catchment surfaces through the emission of SO2. Herold and Görgens (1991) give a summary of the sulphur dioxide emission sources in the Mpumalanga Highveld region. Currently 6 power stations are operational in the Loskop Dam catchment
The sulphate concentration measured in the rainfall and the rainfall depths for the Palmer and Middelburg sites showed that rainfall concentrations are variable and are inversely correlated to the rainfall depths. The model does not allow for a relationship between rainfall and the deposition rate. A single value representing all the deposition modes as well as the generation of pollutant mass from the catchment soils and geology is used in the model. The wet deposition rates were calculated using the measured rainfall depths at the sites and the sulphate concentration measured in the rainfall and totalled for the year.
The results give 1.5 t/km2/a for the Palmer station and 1.0 t/km2/a for the Middelburg station.
The median sulphate concentration values were used to determine a representative wet deposition rate for the management units for the current state of the catchment. The MAP for the management units is about 680 mm.
This gives a wet deposition rate of 1.1 t/km2/a for the Palmer site and 2.8 t/km2/a for the Middelburg site.
These deposition rates are representative of the current emission and atmospheric conditions. The calibration period covers the period from 1986 to 1997. A growth in deposition rate over this period was developed using the growth in installed capacity over time.
4.9.4.7 Calibration of Washoff module
The Washoff module has been enhanced as part of this project to include an absorption/desorption algorithm. This was included based on a report by Herold et al. (1997) and experience in modelling sulphate in the Witbank Dam catchment. A sink term had to be used in the WITSIM model to lose sulphate mass to reduce the rapid growth in the sulphate concentration in the groundwater stores of the model.
4.43 Non-Point Source Pollution Assessment
4.9.4.8 Conclusions and recommendations
The following conclusions and recommendations can be made as a result of the study:
In general, reasonable calibrations of sulphate concentrations were achieved for the background stations and for the dams. However, in impacted catchments such as the Klipspruit, Spookspruit, Steenkoolspruit and the Koringspruit, the calibration against concentration was less successful. For these catchments, the simulated and observed sulphate loads compare more favourably than the concentrations. The results of the modelling will therefore be most accurate for the bulk supply dams but not as accurate in assessing local impacts at the Management Unit level.
The water quality in the Witbank and Middelburg Dam catchments is impacted on by coal mining activities including decants and seeps from opencast pits, discard dumps situated on the banks of the rivers, spills from pollution control dams, Non-Point sources as well as the discharge of excess water to the river system. The measured water quality records in the impacted catchments were often punctuated by uncharacteristic periods of high sulphate concentrations. This made calibration of the WQT model in these management units difficult without knowing the cause of these elevated concentrations.
Data on the storage volumes in the underground workings is inaccurate. This should be updated with the results of the Water Research Commission study on intermine flow.
Additional monitoring information on the inflow to Loskop Dam, the upper Wilge catchment and on the Kromdraaispruit should be considered.
The atmospheric deposition database is expanding and data on the different fallout mechanisms is being collected or generated. The methods of representing the build-up due to deposition should be revised.
The WITSIM model needs to be run per sub-catchment in order to calculate the Non-Point Pollution. This rerun will be undertaken in early 2007.
4.9.5 Case Study 5: Platinum Industry
The following is a personal communication with Peter Sheppard (2006) from SRK who has extensive experience in water balances from platinum mining. “I do not have a report other than those submitted to the mine but my feelings on Non-Point pollution are as follows:
Seepage is about 5-10% of the slurry water deposited onto the tailings dam (This means about 50 000-100 000 m3/month) for a large mine.
Shaft/plant losses to seepage are minimal as most of the polluted areas are concreted (settling dams on the surface are the biggest polluters)
The smelters/refineries have had severe contamination in the past and in this case very poor water qualities were released to the environment
The contribution to catchment salt balances is about 20%
4.10 Mining industry Non-Point Source Pollution contribution
Water and air pollution are both serious problems associated with the mining and processing. The environmental impact of mining and processing operations is dependent on the type of commodity mine, type of mining method, grade of ore and the processes used. Non-Point sources are usually difficult to 4.44 Non-Point Source Pollution Assessment measure because they are highly variable as a result of hydrological processes that vary over time. Mine water waste typically enters the water resource due to seepage, leaching and run-off. Principal Non-Point sources of pollution in the mining industry are:
Dumps (waste rock, slimes dams,
Excavations (surface and groundwater)
Dams and water impoundments
Landfill sites
Irrigation of waste
Spills from pollution control dams, pipelines. Slimes dams
Activities in the mining environment which pose a threat of groundwater contamination include the following:
Disposal of mining and mineral processing wastes (e.g. tailings, slimes, waste rock dumps
Mine wastewater ponds
Mine de-watering and mine drainage
Disposal of waste in unused or abandoned mines
Uncontrolled dumping
Disturbance or damage to aquifers by quarrying, opencast or underground mining
Activities which may result in the alteration of recharge (IGS, 2004).
Activities are specific for different types of mines and hence the pollution type and severity varies depending on the activity and the type of mine. Mines also produce a variety of potential contaminants, depending on the ore deposit type, mining processes and mineral processing activities at specific sites.
By-products from gold mines, include uranium and acid/pyrite, which are potential sources of groundwater pollution and acid mine drainage. Coal mining’s impact on the water resources varies according to the life cycle of the mine and coal mines may produce large quantities of acid or saline mine drainage.
Due to the lack of detailed information on the Non-Point sources of pollution from the South African mining industry, the following factors could not been incorporated into this risk assessment:
The differentiation between the impact of the different receptors (e.g. waste rock dumps) between the different mining commodities.
The age of the receptors. Age plays a major role on the impact as older mining activities did not include good housekeeping and pollution control measures were not put in place. The chemical characterisation of waste receptors also changes over time
The role of gas emissions from the different mining commodities.
The magnitude of the threat from mining activities is dependent on whether precautionary measures are taken to prevent contamination, but in many cases, the scale of mining operations is such that Non-Point sources of pollution cannot be completely avoided
4.45 Non-Point Source Pollution Assessment
Coal and gold mines, especially closed and abandoned mining operations, appear to be the most significant threats in terms of potential groundwater contamination from the mining sector in South Africa. Acid generation and decreasing groundwater pH has been noted in some gold and coal mining areas in South Africa, but in many cases, AMD is neutralised by reaction with the country rock to produce saline drainage instead.
Contamination of groundwater sources from contaminated surface water is possible where there is a direct connection between the resources. The connection to these surface water bodies, contributing to this type of groundwater contamination, can either be natural or man-made.
The range (13 to 51%) of potential Non-Point Source Pollution contributions to salts balances at a catchment scale varied considerably from study to study, commodity mined and season. Despite the uncertainties in the accuracy of these studies the overall contribution of Non-Point Source Pollution originating from the mining industry in South Africa is significant. Detailed catchment modelling would be required to refine the catchment specific contribution of Non-Point Source Pollution originating from the mining industry in South Africa.
4.46 Non-Point Source Pollution Assessment
5 NON-POINT WATER POLLUTION: INDUSTRIES
5.1 INTRODUCTION
This chapter deals with water pollution caused by Non-Point (Non-Point) industrial sources of contamination. Although it is generally recognised that industrial pollution is a significant source of Non- Point pollution, there is not much specific quantitative information in the literature on the actual contribution of industries to Non-Point water pollution. There is a large amount of literature available on potential pollutants from various industries and it is assumed that these contaminants can also occur in Non-Point sources of industrial pollution. These potential contaminants have been included in Table 5.1 where the different categories of industries with potential pollutants are given together with a risk rating. It must however, be emphasised that the risk rating given in the table is a theoretical risk and that each situation must be evaluated on its own merits to arrive at a more realistic risk rating.
5.2 Methodologies
The objective of this part of the project was to gather first order data on Non-Point pollution caused by industries in South Africa. The first task was to do a literature review in order to obtain background data on the situation in South Africa and worldwide. Although a very large number of references containing key words of Non-Point pollution and industry were obtained, few of them actually contained useful information for the purpose of this study. Very little information on industrial Non-Point pollution in South Africa could be found in the literature. A brief summary is given in the literature review section.
In order to obtain more relevant information on the South African situation, a number of personal interviews were conducted with representatives of some industries and other individuals from DWAF and other institutions. A list of people consulted and who commented on reports is given in the last section of this chapter. From this information and from other reports and the literature a categorisation of industries was compiled together with a list of potential pollutants. This was further developed to include a theoretical risk factor for the different categories. It must be pointed out that although there is a large amount of information available in the form of reports on special investigations conducted for individual industries, this data is not readily available because industry in general feel uncertain about how this type of information could affect their situation with regard to future applications for water use or wastewater discharge.
In an attempt to validate the information on the lists and more specifically the approach to assign a risk factor to the different categories, a workshop was arranged as part of the WISA conference in Durban in 2006. A number of presentations were made at the workshop and some useful discussions took place. However, most of the workshop contributions were in the form of general remarks and general discussions and not much specific information was obtained.
As a follow-up to the workshop, the list containing industry categories with potential pollutants and risk factors was distributed to all the members of the WISA Industrial Water Specialist Group with the request to comment and to provide and/or correct information on the list. A relatively small number of comments (13) were received and the feedback was incorporated into Table 5.1.
At this stage a fair amount of information was obtained but most of this was of a general nature and did not contribute to the specific information that was hoped for to establish the fist-order assessment which is the objective of the project.
5.1 Non-Point Source Pollution Assessment
Realising that the only source of quantitative information would be through direct consultation with specific industries a decision was made to select a number of industries that could be approached directly for information. Based on discussions with the project management, four industries were selected for follow-up investigations in an attempt to obtain information that could possibly be used as indicator of the situation in industries in South Africa. The four industries selected are Sasol, SAPPI, NCP Chloorkop and Columbus Steel. Excellent cooperation was received from these industries and a large amount of information was made available to the project team. The time and cooperation by representatives of these companies is highly appreciated.
However, even though some of the information is in the public domain, the industry representatives are hesitant to give permission for the information to be presented in a WRC report. The reasons for this are obvious and understandable since the information is of such a nature that it could reflect negatively on the industries if it is used in a malevolent manner.
The end result of all these factors is that the first-order assessment of Non-Point pollution by industry can only be given in general terms. However, the nature of the assessment is such that it provides a good basis for follow-up studies on specific areas with the greatest potential for Non-Point pollution from industries.
5.3 Main environmental regulatory tools currently available in South Africa to manage industrial activities
The section below deals briefly with the main environmental regulatory tools currently available in South Africa to manage industrial activities with special emphasis on management of Non-Point pollution.
5.3.1 Constitution of the Republic of South Africa Act (Constitution) (Act 108 of 1996)
Certain of the fundamental rights contained in the Constitution are aimed at protection of the environment against degradation and pollution (Heath and Eksteen, 2005). These include in particular section 24 (“Environment”) and section 33 (“Just Administrative Action”). Section 24 of the Constitution provides that “everyone has the right … to an environment that is not harmful to their health or well-being; and … to have the environment protected for the benefit of present and future generations through reasonable legislative and other measures that – (i) prevent pollution and ecological degradation; (ii) promote conservation; and (iii) secure ecologically sustainable development and use of natural resources while promoting justifiable economic and social development”. Section 33 of the Constitution entitles everyone to administrative action that is lawful, reasonable and procedurally fair and, if one’s rights have been adversely affected by administrative action, to be given written reasons for the decision.
5.3.2 National Environmental Management Act (NEMA) (Act 107 OF 1998)
The National Environmental Management Act (NEMA) stipulates certain environmental management principles that apply throughout the country to the actions of all organs of state that may significantly affect the environment (Heath and Eksteen, 2005). These include, amongst others:
Sustainable development
Risk aversion and precaution
Integrated environmental management
Environmental justice
5.2 Non-Point Source Pollution Assessment
Equitable access (redressing issues of the past)
Cradle to grave (life cycle)
Public participation and consultation
Internalisation of costs (polluter pays)
Beneficial use of natural resources
NEMA establishes a general duty of care on every person who causes, has caused or may cause significant pollution or degradation of the environment to take reasonable measures to prevent such pollution or degradation from occurring, continuing or recurring, or, in so far as such harm to the environment is authorised by law or cannot reasonably be avoided or stopped, to minimise and rectify such pollution or degradation of the environment (Heath and Eksteen, 2005).
5.3.3 National Water Act (NWA) (Act 36 of 1998)
The National Water Act (NWA) iterates the general duty of care on persons who own, control, use or occupy land on which any activity or process is or was performed or undertaken, or any other situation exists which causes, has caused or is likely to cause pollution of a water resource, to take all reasonable measures to prevent any such pollution from occurring, continuing or recurring (Heath and Eksteen, 2005).
5.3.4 Cooperative Governance
The spirit of the applications of the various Acts and regulations in South Africa is one of co-operative governance (Heath and Eksteen, 2005). As can be seen above no single Act or government department has total control over the mining and environmental issues. Consequently it is important that the government department co-operate and share the application of applying the legislation in a sustainable manner (Heath and Eksteen, 2005).
5.3.5 Other forms of Regulatory Assistance
A number of other environmental tools/instruments are currently employed (or in certain cases being developed) in South Africa to assist with the day-to-day management of mining activities (Heath and Eksteen, 2005). These include:
Command and control instruments
- Waste discharge standards (water, air quality) - Licensing (water use and waste disposal)
- Monitoring and auditing requirements
Best practice guidelines
- Guidelines on financial provision – DME
- Best practice guidelines for water quality management in the SA mining industry – DWAF
Market-based instruments
5.3 Non-Point Source Pollution Assessment
- Pollution taxes (waste discharge charges) - Tradable permits (water use) - Triple bottom-line accounting
- International pressure for green products (eco-labelling)
Social instruments
- Performance reporting - Public participation and consultation
- General duty of care
Industry co-regulation / self-regulation
- Environmental Management Systems (ISO 14001)
- Internal HSEC reporting and performance requirements (waste minimisation, reduction in use of natural resources)
- International norms and pressures (multinational companies mining in South Africa and trading partners)
5.4 Literature review and industry survey
5.4.1 Introduction
Non-Point pollution (or Non-Point Source Pollution) is the subject of a very large number of research reports in literature. By far the largest part of literature reports deal with Non-Point pollution in agriculture, in particular with Non-Point pollution by nitrogen and phosphorous. A number of reports deal with Non- Point pollution from mining activities, from petrochemical industries, in urban runoff, by heavy metals and from atmospheric sources. A further category deals with Non-Point pollution modelling and strategies to control or minimise Non-Point pollution. Very few literature articles of substances are available specifically on Non-Point pollution from industries.
Literature on the South African situation with respect to Non-Point pollution is limited to a number of reports on assessment methods and management methods in a number of Water Research Commission (WRC) reports, as well as some general reports on the contribution of Non-Point pollution to water quality problems in some catchments. Virtually no publications specifically on Non-Point pollution emanating from industry are available in the open literature. However, this does not mean that no information is available on industrial Non-Point pollution. It is clear from discussions with a number of officials in the Department of Water Affairs and Forestry (DWAF) as well as consultants and people in industry that contract reports and other classified reports exist but that they could not be accessed without approval from the specific companies. Furthermore, that information on industrial contribution to Non-Point pollution could also be extracted from catchment studies and catchment management models.
The polluted runoff (Non-Point Source Pollution) problem in the USA is described in a number of USEPA articles but again no report specifically on industrial Non-Point sources:
5.4 Non-Point Source Pollution Assessment
Non-Point Source Pollution: The Nation's Largest Water Quality Problem (EPA 841 – F – 96 – 004A).
Opportunities for Public Involvement in Non-Point Source Control (EPA 841 – F – 96 – 004B).
Programs for Non-Point Source Control (EPA 841 – F – 96 – 004C).
The Non-Point Source Management Program (EPA 841 – F – 96 – 004D).
Managing Non-Point Source Pollution from Agriculture (EPA 841 – F – 96 – 004F).
Managing Urban Runoff (EPA 841 – F – 96 – 004G).
Managing Non-Point Source Pollution from Forestry (EPA 841 – F – 96 – 004H).
Managing Non-Point Source Pollution from Boating and Marinas (EPA 841 – F – 96 – 004I).
Managing Non-Point Source Pollution from Households (EPA 841 – F – 96 – 004J).
Managing Wetlands to Control Non-Point Source Pollution (EPA 841 – F – 96 – 004K).
In view of the lack of specific information on Non-Point industrial pollution in the literature, this review includes information gathered through personal discussions with people from DWAF and industry and also from the personal experience of the authors. An initial assessment is also made of industries and areas where the biggest impact from Non-Point pollution might be expected.
5.4.2 Industrial wastes
Wastes generated by industries can be liquid, gaseous or solid. These three forms in which wastes are generated can all contribute to Non-Point water pollution. Treatment and discharge of liquid wastes are normally well controlled by DWAF requirements. However, illegal or non-controlled discharge of liquid waste can significantly contribute to water pollution and such discharges would normally not be recorded as point discharges. Major Non-Point or Non-Point sources of industrial origin appear to be solid industrial wastes and gaseous emissions. The sources of Non-Point pollution from industrial sources can be categorised as follows: Surface runoff contaminated by onsite solid waste depositions
Groundwater contamination by seepage from onsite waste depositions
Onsite disposal of effluents
Surface water and groundwater pollution from waste disposal sites
Atmospheric emissions depositing on water surfaces and soil and contaminating runoff
Illegal discharges of contaminated water
Illegal disposal of solid wastes or residues
Any (or all) of these sources might be relevant for any industry and there may be significant differences between members of the same industry. This means that it will require a major effort to try and quantify Non-Point pollution from any particular industry. It will therefore be necessary to identify industries that could have the largest effects as potential Non-Point sources of pollution and focus efforts on them.
5.5 Non-Point Source Pollution Assessment
5.4.3 Potential sources of Non-Point industrial pollution
5.4.3.1 Storm water runoff contaminated by onsite storage of material and waste
Industrial sites vary in size from small sites within the boundaries of a local authority to very large sites covering many square kilometres, such as Sasol, ISCOR, Foskor, etc. A common feature of all industrial sites is that many different materials are stored on these sites, including raw materials, intermediates, final products, various wastes, etc. Such sites are therefore potential sources of pollution due to the possibility of leakages, spillages, or generally poor housekeeping. This may result in contamination of stormwater, which has to be properly controlled to prevent pollution of water sources.
Management of surface runoff from industrial sites must comply with DWAF requirements or requirements in terms of bylaws from local authorities. These requirements include measures such as monitoring, collection and treatment of runoff or disposal of contaminated runoff into the sewer system (DWAF, Bylaws). However, in most cases only large industries have systems in place that enable them to comply with these requirements. It can also be assumed that within municipal areas only larger local authorities will be able to enforce such requirements. Currently the situation in most small and medium size local authorities is such that they have difficulty to provide basic services and control of Non-Point pollution would not be high on their priority list.
It could therefore be assumed that storm water pollution from industrial sites within municipal areas would be a major source of industrial contaminants contributing to Non-Point pollution in these areas. However, virtually no information on South African conditions is available in the literature to substantiate this. The heavy metal content of storm water runoff could be used as one indicator of Non-Point industrial pollution.
5.4.3.2 Groundwater contamination by infiltration of contaminated water
Infiltration of contaminated storm water can potentially pollute groundwater below an industrial site. DWAF guidelines include requirements about collection of contaminated surface water to prevent infiltration and potential pollution of groundwater.
5.4.3.3 Onsite disposal of effluents
In some cases industries dispose of certain effluents onsite. These could be effluents that are difficult or expensive to treat such as brines or concentrates that are stored (disposed of) in evaporation dams. This practice is controlled by DWAF but it remains a source of potential groundwater pollution.
5.4.3.4 Surface water and groundwater pollution from waste disposal sites
Industrial wastes emanating from production processes or water treatment processes that cannot be recycled or reused are disposed of in landfill sites or hazardous waste disposal sites. These sites could be managed by the industry, e.g. ash disposal, or by a private company. In all such cases the sites must comply with the minimum requirements for waste disposal sites administered by DWAF. Leakages and seepage from such sites contribute to Non-Point pollution, mainly of groundwater.
5.4.3.5 Atmospheric emissions depositing on water surfaces or soil and contaminating runoff
Atmospheric emissions from industries include gasses such as CO2, SO2, CH4, NOx, other volatile substances such as chlorinated hydrocarbons as well as particulate matter such as fly ash, soot, etc. An estimate can be made of the mass of combustion products emitted by industries, but it is rather difficult to
5.6 Non-Point Source Pollution Assessment calculate the actual mass of material deposited and the mass ending up and contaminating water sources.
5.4.3.6 Illegal discharge of wastes and contaminated water
Illegal discharge of contaminated water contributes to Non-Point pollution since it is not recorded as a point discharge. Illegal disposal of solid wastes and residues typically involves simply dumping of the unwanted material and therefore is simply washed into the nearest watercourse with the first rainstorm.
5.4.4 Industry categories based on type of waste /effect on water resources
Industries can be categorised in a number of ways depending on the objective of the exercise. This categorisation aims to group different industries together that produce similar wastes or wastes that have similar effects on the quality of water sources. As starting point wastes can be distinguished as either organic or inorganic in nature. Further categories can include whether organic wastes are natural or synthetic, biodegradable or non-biodegradable, suspended or dissolved, volatile or non-volatile. Further categories for inorganic wastes can include whether they are suspended or dissolved, metallic or non- metallic, toxic or non-toxic. Most industries produce different types of wastes and may therefore fall in more than one category.
The following is a suggested categorisation of South Africa industries based on the types of wastes they produce.
5.4.4.1 Industries producing organic wastes
Natural readily-biodegradable wastes
Abattoirs
Malting, brewing, yeast manufacturing
Wineries
Food processing and packaging
Dairy industries
Catering
Laundry
Chemical industry (fatty acids)
Detergents, health care, cosmetics
Natural non / slowly biodegradable wastes
Textile industries
Wool industries
Leather and hides
Pulp and paper
5.7 Non-Point Source Pollution Assessment
Petroleum
Cleaning, health care and cosmetics
Synthetic organic chemical wastes
Chemical industries
Plastics
Paint
Textiles
Petrochemical industries
Detergents and health care
5.4.4.2 Industries producing inorganic wastes
Heavy chemicals wastes
Acid-base manufacturing wastes
Chlor-alkali manufacturing
Fine chemicals
Fertilizers
Cement manufacture
Ceramics, bricks, sanitary ware
Metallic wastes
Metal manufacturing and processing
Metal finishing and plating
5.4.5 Priority industries with biggest potential for Non-Point pollution
The following discussion is based on personal discussions with DWAF officials and consultants involved in water quality management and control and on the authors’ personal experience in this field.
When considering the contribution of industries to Non-Point pollution, a distinction must be made between industries within municipal boundaries and those in industrial complexes (whether a single industry or group of industries).
Industries within municipal boundaries fall under control of municipal bylaws and mostly discharge effluents to the municipal sewer. Control of storm water pollution from industrial sites is also controlled by municipal bylaws. Local authorities have responsibility for collection, drainage and disposal of urban storm water, including storm water from industries within their boundaries and must therefore control
5.8 Non-Point Source Pollution Assessment pollution of storm water by industries. However, there is a big concern about the capacity of local authorities to control storm water contamination by Non-Point pollution from industries.
Most of the Non-Point pollution emanating from industries in municipal areas would be very difficult to account for since it is actually ‘hidden’ in urban storm water. Non-Point pollution from these industries is mostly related to runoff resulting from rain events, making it even more difficult to quantify. There are however, also continuous sources of Non-Point pollution that should be easier to identify and quantify such as streams leaving premises during dry spells. Possible causes of these include leakage from storage tanks, seepage from wet material, etc.
The priority industries suspected of causing the largest Non-Point pollution include the following for the country as a whole and for some of the DWAF regions:
The large industrial complexes such as Sasol, ISCOR, Foskor, Sappi, refineries, AECI, Saldana Steel, etc. In most of these cases reports exist containing information on Non-Point pollution compiled for individual companies or the complexes as a whole. These are normally classified and not available without permission from the industry or consultant. These companies could be contacted and information on Non-Point pollution requested. Alternatively, it might be possible to obtain access to the information through DWAF. The groundwater pollution from Non-Point sources from the ISCOR complex in Vanderbijlpark is an outstanding example but perhaps not typical of most of these complexes.
Feedlots, piggeries, broiler raising and similar undertakings where large numbers of animals are raised, kept, slaughtered and the products processed and packaged. It is not clear whether these are covered under agriculture or should be included in this study on industries. The same question also pertains to dairy farms and processing of milk and other dairy products.
Wineries and fruit processing are considered to be the major contributory industries to Non-Point pollution in the Western Cape. The main problem is related to the storage, processing and application to soil of the solid residues from these industries. The residues are stored and composted before application to soil and there is a large potential for pollution during this process that continues for a few months during the year.
The Non-Point pollution potential from breweries and other food processing industries is also related to the disposal of solid residues as well as from storage and washing of raw materials, equipment, bottles and containers.
In the Eastern Cape the wool washing and processing industry has a large Non-Point pollution potential.
In the KwaZulu-Natal region the textile industry and sugar processing industry are considered to be major Non-Point pollution sources.
The leather processing industry a major Non-Point pollution problem. Especially the storage and processing of the different types of hides has a large pollution potential.
In the Mpumalanga and KwaZulu-Natal regions the pulp and paper industry is considered to constitute a major Non-Point pollution problem.
All industries for the manufacturing, storage, processing and packaging of chemical compounds and products have the potential for Non-Point pollution. The smaller members of these industries are normally located within municipal boundaries of industrial townships and therefore fall under the control of the local authority. The larger industries such as those manufacturing fertilizers, cement, paints, personal care products, etc. have a large potential for Non-Point pollution.
5.9 Non-Point Source Pollution Assessment
Metals and minerals processing industries are also potential sources of Non-Point pollution. These range from small ‘backyard’ operations to very large industries such as Columbus Steel and vehicle manufacturers. An example of these industries is Manganese Metals Company that has large highly contaminated evaporation dams with very high Non-Point pollution potential.
Many industries have boilers for steam generation and process heating and therefore produce ash and other wastes that have to be disposed of. Although at a much smaller scale than Eskom’s power plants their situation is similar and if large quantities of ash are produced this could be a source of Non-Point pollution.
Many large service industries such as the transport industry also have a potential for Non-Point pollution. For example washing of buses, lorries, containers and rail trucks is a potential source of Non-Point pollution.
5.4.6 Literature on Non-Point pollution in specific industries
5.4.6.1 Petroleum refineries
Meso-scale transport and diffusion modelling of industrial air pollution data from the Fos-Berre l'Etang area, France, show very high values of deposition for Zn and Ti over the western Mediterranean Sea 40 and 130 km downwind (Gomes et al. 1985). The model was used to quantify emissions to estimate the relative importance of particulate heavy metals from industry. High values of Cadmium are attributed to the large number of petroleum refineries in the area. Sulfur dioxide contributes 4,5-9% to the pollution. Emissions from this industrial complex contribute 2-10% of the trace element air pollution in France.
5.4.6.2 Petrochemical industries
Measurement and control of Non-Point pollution at the BASF company in Germany is reported on in detail by Herrmann and Siegle (1998). This report (in German) contains a large amount of data and they define Non-Point emissions as the ‘unavoidable leakages from armatures, flanges, and pump shafts. According to their studies since 1968 the total emissions reduced drastically over this period while the contribution of Non-Point sources remained at between 1,5% and 2%. However, when only organic substances are included the contribution of Non-Point sources increased from 5% to 17% of the total releases while the mass of releases decreased from 3200 to 1800 t/a.
The Southern part of Romania is a highly industrialized region, including petroleum refining, ferrous, non- ferrous, and chemical industries as well as power generation constituting point sources. The results on monitoring of oil pollution around the town of Ploiesti (South Romania), known for its petrochemical and chemical industry complexes and crude oil activity, are reported on by Oprea and Mihul (2003). The distribution of heavy metals, rare earth and other microelements along the wind rose profile (the oil complex at 20 km distance) was examined through the analysis of soil samples. Mosses were chosen as biomonitors of local atmospheric pollution with heavy metals and other toxic elements. The trace element content of vegetation growing near the plant was compared with that of background vegetation. The contamination of the river flowing in the vicinity of the plant was examined. Comparison of the spatial trends of different pollutants shows the influence of the same atmospheric transport phases on the uptake of trace elements by vegetation. A comparative evaluation of the results was carried out to indicate to what extent the amount. of pollutants in the atmospheric or the amount deposited in the soil or transported by sediments contributes to pollution of the local ecosystem in the vicinity of a petrochemical center.
5.10 Non-Point Source Pollution Assessment
5.4.6.3 Heavy metal industries
The amount of discharge into German waters of the heavy metals As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn were estimated for the first time for Germany as a whole (Boehm et al. 2001). The discharges were distinguished according to direct industrial and municipal point sources as well as Non-Point pollutant sources and classified according to areas of origin (sectors) and emission paths as well as the large river basins of the Danube, Rhine, Ems, Weser, Elbe, Oder, the North and the Baltic Seas. The reference time period was 1993-1997 and 1997 for the industrial direct emitters. For the inventory, very different individual and aggregated data were used such as Federal state monitoring data, international reports, environmental reports of companies, reports from industrial associations and the results of different research projects. The quality of the available data was very varied, and they therefore had to be checked for compatibility. The share of Non-Point heavy metal sources was on average about 75%. The most important input paths for Non-Point emissions are urban areas (mainly the volume of water which is diverted directly into water bodies when it rains via the separated or combined systems) and erosion with both 31% on average, as well as the input via groundwater with about 20%. An important source for cadmium and zinc emissions is also drainage with 15% of the total Non-Point emissions. The point sources can be divided into municipal and industrial discharges with the share of municipal emissions for heavy metals about 77% (between 62% for lead and almost 93% for mercury). The most important industrial branch is the chemical industry with 40% of the total industrial discharge.
Mercury as a pollutant is emerging as a significant issue in the southeastern United States due to recent emphasis by the U.S. EPA on the Total Maximum Daily Load (TMDL) provisions of the Clean Water Act (Dean et al. 2000). Several additional factors have heightened the concerns of industry with regard to mercury. Recently proposed changes to the TMDL regulations specifically name air deposition as a Non- Point source of pollution that must be considered in TMDL analyses. Therefore, many waste incinerators and fossil fuel-fired industrial boilers will come under added scrutiny. The net effect of these new developments is that many facilities previously immune to this issue may find themselves embroiled in mercury TMDLs. This paper discusses sources of mercury in the southeastern U.S., both natural and anthropogenic, specific situations under which mercury can become methylated and bio-accumulate in fish, and review the current status of mercury fish consumption advisories and TMDLs. It concludes with a discussion of the potential impacts of mercury TMDLs on the pulp and paper industry.
5.4.7 Environmental issues associated with specific industrial sectors
The U.S. Environmental Protection Agency (EPA) has published a series of volumes to provide information of general interest regarding environmental issues associated with specific industrial sectors (www.epa.gov/oeca/sector)
These volumes deal with issues like:
Industrial process description (raw materials inputs and pollution outputs; management of chemicals in waste streams), chemical release and transfer profile (EPA toxic release inventory), and pollution prevention opportunities.
The specific industries are listed at the end of this document together with the EPA document numbers.
5.4.8 Identification and prioritisation of groundwater contaminants and sources in South Africa’s urban catchments
A comprehensive study was recently conducted (WRC 2004) with the aims to: a) identify and prioritise the
5.11 Non-Point Source Pollution Assessment type of contaminants and their associated sources (industry, agriculture, mining and others) which present a threat to groundwater, the environment and health in South Africa’s urban catchments; b) formulate strategies for better understanding the impacts of polluting activities on groundwater resources in urban catchments; c) establish a data information system on South Africa’s contaminants.
The products resulting from the research are: a. A tiered risk based prioritisation tool with which both sources and contaminants can be rated. b. An excel-based data information system in which contaminants, associated sources and contaminant properties are stored.
Contaminants found in the urban environment can be prioritised on a national, regional and local scale. These priority lists are based on a national inventory, together with inventories for regional and local sectors.
The types of industrial sources include: a. Urban settlement (domestics/commercial): railroad yards; hazardous waste sites; petrol service stations; photographic manufacture and uses; printing industry, dry cleaning activities, etc. b. Non-metallurgical industries: adhesives and sealants; leather manufacturing; pharmaceuticals and cosmetics manufacturing; non-metallic mineral products; paper/pulp industry; textiles manufacturing; manufacturing chemicals, solvents; etc. c. Metallurgical and metal products manufacturing: metallurgical; automotive manufacturing, other metal products manufacturing; etc.
Case studies were reported showing Non-Point pollution occurring in the metal plating industry, certain industrial complexes, wood treatment, oil refining, chemical manufacturing, underground storage tanks (petroleum products) and from waste disposal sites.
5.5 Industry categorisation and risk factor assessment
There are many approaches and systems available to assess or evaluate risk of different sources and / or contaminants to water pollution. A number of these are discussed in the WRC Report 1326/1/04. However these methods were not found suitable for the purpose of assigning risk to the industry categories in this report.
The following simple system provides an easy possible way of ranking industries according to potential impacts due to Non-Point water pollution. The approach is to evaluate 3 factors and assign a rating to each. By assuming equal weights initially of these factors they can be multiplied to give an overall potential pollution rating. It is recognised that this ranking system could be improved and refined by including more factors or can be refined by being more specific. Such improvements can be included for use in follow-up projects if required.
The factors as indicated in Table 5.1 are:
Size of industry – mass/volume of raw materials/products/waste produced (M in Table 5.1). Rating 1-5: 1 for very small operations, 2 small, 3 medium, 4 large, 5 very large. At this stage a qualitative judgement is used that could be improved by collecting actual data.
Potential health implications of contaminants in wastes (H in Table 5.1). Rating 1-4: 1 for minimal impact, 2 for low toxicity levels of some compounds used, 3 for high intermediate toxic levels and 4
5.12 Non-Point Source Pollution Assessment
for high toxic levels. The problem here is that in many industries some hazardous products are used and it is almost impossible to separately classify and rank each product as part of an industry categorisation.
General (non-health) impact on water quality related to cost of treatment or cost of quality deterioration of receiving water (TDS, SS, etc.) (G in Table 5.1). Rating 1-5.
A logarithmic scale was considered to increase the scale/range of effects, but it was decided to use the simpler linear system. If equal weight is assigned to these factors, multiplication yields 1*1*1 = 1 for no impact, while maximum impact is 5*4*5 = 100. This gives a range of 1-100 which makes it easy to rank industries according to pollution potential.
The initial ratings are based on information in the literature and on personal assessment by the authors. The objective is to distribute this document to different industries to get their input on ratings (and possibly weighting factors) in order to improve the data and ranking.
5.13 Non-Point Source Pollution Assessment
Table 5.1: Classification and risk associated with Non-Point pollution from industry
POTENTIAL POLLUTION INDUSTRY SOURCES PATHWAYS MHGTOTNOTES CONTAMINANTS RISK Some large industrial Risk of premises, variety Surface runoff, polluted runoff of base and more Very large range of Storage of liquid and solid seepage/leaching and storm complex chemicals Chemical potential pollutants waste, poor housekeeping, from waste water pollution. (used and manufacturing depending on products, leaking seals and glands, 5 4 5 100 storage and Risk of produced), often industries raw materials and nature improper/illegal disposal of disposal sites, air seepage and own waste of processes wastes, air emissions emissions groundwater disposal pollution areas/ponds. Also some small facilities
Risk of polluted runoff Acids and alkalis, variety Storage of liquid and solid Surface runoff, and storm of base and heavy metals, waste, poor housekeeping, seepage/leaching Acids, alkalis, water pollution. brine solutions, leaking seals and glands, from waste 5 3 4 60 inorganic chemicals Risk of suspended solids, improper/illegal disposal of storage and seepage and chlorine, ammonia wastes disposal sites groundwater pollution
5.14 Non-Point Source Pollution Assessment
POTENTIAL POLLUTION INDUSTRY SOURCES PATHWAYS MHGTOTNOTES CONTAMINANTS RISK Risk of polluted runoff Surface runoff, and storm Storage of liquid and solid seepage/leaching Acrylonitrile, butadiene, water pollution. waste, poor housekeeping, from solid and chloroform, DCE, phenols, Risk of Rubber and Plastic leaking seals and glands, liquid waste 4 4 4 64 phthalates, styrene, vinyl seepage and improper/illegal disposal of storage and chloride groundwater wastes disposal sites, air pollution emissions
Carbon tetrachloride, Risk of chlorofluoroethanes, DCE, polluted runoff methylene chloride, PCE, and storm Surface runoff, TCE, vinyl chloride, water pollution. Storage of liquid and solid seepage/leaching alcohols, acetates, Risk of waste, poor housekeeping, from solid and Solvents, adhesives ketones, chlorinated seepage and leaking seals and glands, liquid waste 3 4 4 48 and detergents solvents, formaldehyde, groundwater improper/illegal disposal of storage and isocyanates naphthalene, pollution wastes, air emissions disposal sites, air mineral spirits, phenol, emissions phthalates, organophosphates, surfactants
5.15 Non-Point Source Pollution Assessment
POTENTIAL POLLUTION INDUSTRY SOURCES PATHWAYS MHGTOTNOTES CONTAMINANTS RISK Risk of Ammonia, arsenic, polluted runoff chlorides, lead, and storm phosphates, potassium, Surface runoff, water pollution. nitrates, sulphur, arsenic, Storage of liquid and solid seepage/leaching Risk of carbamates, chlorinated Fertilizers and waste, poor housekeeping, from solid and seepage and insecticides, cyanides, agricultural leaking seals and glands, liquid waste groundwater 5 3 4 60 ethylbenzene, lead, chemicals improper/illegal disposal of storage and pollution naphthalene, wastes disposal sites, air organophosphates, emissions phenols, phthalates, toluene, xylene, dioxin, metals, herbicides
Risk of polluted runoff Alcohols, benzoates, Surface runoff, and storm dyes, glycols, mineral Storage of liquid and solid seepage/leaching Pharmaceuticals and water pollution. spirits As Cd Cr Cu Pb Hg waste, improper/illegal from waste 3 4 3 36 cosmetics Risk of dichlorobenzene, disposal of wastes storage and seepage and methylene chloride, nitrate disposal groundwater pollution
5.16 Non-Point Source Pollution Assessment
POTENTIAL POLLUTION INDUSTRY SOURCES PATHWAYS MHGTOTNOTES CONTAMINANTS RISK
Silver bromide, methylene Surface runoff, Storage of liquid and solid chloride, solvents, seepage/leaching Photographic and waste, poor housekeeping, photographic products from waste 2 4 3 24 printing improper/illegal disposal of waste oils, toluene, MEK, storage and wastes xylene, TCE disposal
Risk of NH NO Ethyl acetate, Surface runoff, 4 3 polluted runoff HMX, methanol, seepage/leaching Storage of liquid and solid and storm nitrobenzenes, from solid and waste, poor housekeeping, water pollution. Explosives nitroglycerine, liquid waste 3 4 5 60 improper/illegal disposal of Risk of nitrotoluenes, PETN, storage and wastes seepage and RDX, tetrazene, tetryl, 1,3- disposal sites, air groundwater DNB emissions pollution
Risk of Surface runoff, polluted runoff Acetic acid, acetone, Storage of liquid and solid seepage/leaching and storm acrylates, chlorinated waste, poor housekeeping, from solid and water pollution. Textiles solvents, formaldehyde, leaking seals and glands, liquid waste 3 3 4 36 Risk of naphthalene, phenols, improper/illegal disposal of storage and seepage and phthalates wastes disposal sites, air groundwater emissions pollution
5.17 Non-Point Source Pollution Assessment
POTENTIAL POLLUTION INDUSTRY SOURCES PATHWAYS MHGTOTNOTES CONTAMINANTS RISK Risk of Surface runoff, polluted runoff Typically large seepage/leaching Dioxins, Storage of liquid and solid and storm areas with high from solid and pentachlorophenol, waste, poor housekeeping, water pollution. potential for Timber treatment liquid waste 3 4 3 36 phenol, tri-n-butyl tin oxide improper/illegal disposal of Risk of pollution from storage and Creosote, PAH, As Cr Cu wastes seepage and noxious and toxic disposal sites, air groundwater chemicals used emissions pollution
5.18 Non-Point Source Pollution Assessment
POTENTIAL POLLUTION INDUSTRY SOURCES PATHWAYS MHGTOTNOTES CONTAMINANTS RISK
Petroleum Industries Risk of Surface runoff, Alkanes polluted runoff Storage of liquid and solid seepage/leaching Large complexes and storm waste, poor housekeeping, from solid and with complex BTEX PAH Oily wastes water pollution. Refineries leaking seals and glands, liquid waste 4 4 3 48 treatment and Solvent residues Organic Risk of improper/illegal disposal of storage and disposal systems. acids & alcohols, seepage and wastes disposal sites, air Difficult control hydrocarbons groundwater emissions pollution
Risk of Variety of chemicals and Surface runoff, polluted runoff hydrocarbons, alkanes Storage of liquid and solid seepage/leaching Large complexes and storm waste, poor housekeeping, from solid and with complex Petro-chemical water pollution. BTEX PAH, oily wastes, leaking seals and glands, liquid waste 5 4 4 80 treatment and industries Risk of solvent residues, organic improper/illegal disposal of storage and disposal systems. seepage and acids & alcohols, wastes disposal sites, air Difficult control groundwater hydrocarbons emissions pollution
Benzene, toluene, xylenes Hydrocarbons (BTEX), Risk of Large numbers of Petroleum Petrol service oxygenates (alcohols, Leaking underground seepage and underground tanks products leaking 4 4 4 64 stations MTBE), metals (lead, storage tanks groundwater are old and from tanks nickel), sulphur, alkanes, pollution corroded TPH, PAH
5.19 Non-Point Source Pollution Assessment
POTENTIAL POLLUTION INDUSTRY SOURCES PATHWAYS MHGTOTNOTES CONTAMINANTS RISK Acids, mineral oils, sulphur, cyanide, metals (including aluminium, Usually large beryllium, cadmium, Storage of liquid and solid Risk for industrial chromium, cobalt, iron, Overflow of waste, poor housekeeping, groundwater, premises, variety Metallurgical strontium, tin, titanium, storage ponds, leaking seals and glands, storm water 4 3 4 48 of chemicals used, Industries vanadium, lead, copper, seepage, leaching, improper/illegal disposal of pollution, air often have own mercury, nickel, zinc and air emissions wastes pollution waste disposal arsenic), dioxins and areas/ponds furans, organic solvents, chlorobenzenes, PCBs, asbestos, fluoride
Various metals such as Many small, few cadmium, beryllium large factories. chromium, cyanide, Risk of storm Small ones mostly copper, silver, tin, zinc and Surface runoff, water pollution in urban areas Waste electroplating metals Electroplating nickel, benzene, improper/illegal where poor 3 4 4 48 and chemicals trichloroethane and disposal housekeeping trichloroethylene, VOCs, and control
dioxin, degreasing agents, waste oils
5.20 Non-Point Source Pollution Assessment
POTENTIAL POLLUTION INDUSTRY SOURCES PATHWAYS MHGTOTNOTES CONTAMINANTS RISK Various metals such as cadmium, beryllium chromium, cyanide, Polluted storm Spillages, copper, silver, tin, zinc and water, seepage, accidents, illegal Automotive Waste chemicals, solid Limited nickel, benzene, leaching from 3 3 3 27 disposal may manufacturing waste, vapour emissions pollution risk trichloroethane and yards and waste occur but trichloroethylene, VOCs, sites likelihood is small dioxin, degreasing agents, waste oils, waste paints
Metals, asbestos, PCBs, Pollution risk hydraulic fluids and from illegal lubricating oils, fuels and Polluted storm disposal of solvents, waste oils, Repair shops water, seepage, waste oils and Auto salvage/repair toluene, acetone, Waste oils, chemicals, solid mostly in urban leaching from chemicals. 2 3 2 12 metal recyclers perchloroethylene, xylene, waste areas, scrap yards yards and waste Storm water gasoline and diesel fuel, on town fringes sites pollution risk carbon tetrachloride and from scrap hydrochloric and yards phosphoric acid
5.21 Non-Point Source Pollution Assessment
POTENTIAL POLLUTION INDUSTRY SOURCES PATHWAYS MHGTOTNOTES CONTAMINANTS RISK
Agricultural Industries Risk of polluted runoff Storage of liquid and solid Polluted storm and storm SS, solid wastes, fats, waste, poor housekeeping, water, seepage, water pollution. Abattoirs blood, pathogens, lairage 4 3 4 48 improper/illegal disposal of leaching from Risk of wastes, brines, nutrients wastes waste sites seepage and groundwater pollution
Risk of polluted runoff Storage of liquid and solid Polluted storm and storm Fats, waste milk, whey, waste, poor housekeeping, water, seepage, water pollution. Dairies 4 2 2 32 wash water improper/illegal disposal of leaching from Risk of wastes waste sites seepage and groundwater pollution
Risk of Storage of liquid and solid Polluted storm polluted runoff DOC, nutrients (organic Feedlots & poultry waste, poor housekeeping, water, seepage, . Risk of nitrate), bacterial 4 3 4 48 farms improper/illegal disposal of leaching from seepage and pathogens wastes waste sites groundwater pollution
5.22 Non-Point Source Pollution Assessment
POTENTIAL POLLUTION INDUSTRY SOURCES PATHWAYS MHGTOTNOTES CONTAMINANTS RISK Risk of Storage of liquid and solid Polluted storm polluted runoff SS, solid waste, organic Food processing & waste, poor housekeeping, water, seepage, . Risk of waste products, effluent, 3 2 4 24 packaging improper/ illegal disposal of leaching from seepage and herbicides, pesticides wastes waste sites groundwater pollution
Risk of Polluted storm polluted runoff SS, steep water, spent Storage of liquid and solid water, seepage, . Risk of Breweries grain, filter cake, wash waste, improper/ illegal 3 2 3 18 leaching from seepage and water disposal of wastes waste sites groundwater pollution
Risk of Storage of liquid and solid Polluted storm polluted runoff SS, solid wastes, liquid waste, poor housekeeping, water, seepage, . Risk of Wineries 3 2 3 18 wastes, acids, bases improper/ illegal disposal of leaching from seepage and wastes waste sites groundwater pollution
Risk of Storage of liquid and solid Polluted storm polluted runoff Edible oil waste, poor housekeeping, water, seepage, . Risk of SS, meal, oil, solvent 2 2 2 8 manufacturing improper/illegal disposal of leaching from seepage and wastes waste sites groundwater pollution
5.23 Non-Point Source Pollution Assessment
POTENTIAL POLLUTION INDUSTRY SOURCES PATHWAYS MHGTOTNOTES CONTAMINANTS RISK Risk of Fats, SS, brines, Storage of liquid and solid Polluted storm polluted runoff chromium, dyes, toluene, Wool, leather & waste, poor housekeeping, water, seepage, . Risk of benzene, arsenic, 2 2 4 16 textiles improper/illegal disposal of leaching from seepage and chromium, cadmium, wastes waste sites groundwater sulphate pollution
5.24 Non-Point Source Pollution Assessment
POTENTIAL POLLUTION INDUSTRY SOURCES PATHWAYS MHGTOTNOTES CONTAMINANTS RISK
Pulp, Paper & Printing Industries SS, TDS, carbohydrates, Risk of lignin acrylates, polluted runoff chlorinated solvents, Overflow of and storm Typically large Pulp and paper dioxine, mercury, phenols, Variety of waste streams storage ponds, water pollution. operations with 4 3 4 48 manufacture styrene, sulphur, furans, and solid wastes seepage, leaching, Risk of own treatment and chloroform, mercury, air emissions seepage and disposal facilities sulphate, potassium groundwater dichromate pollution
SS, TDS, carbohydrates, Risk of chlorinated solvents, Waste chemicals and solid Illegal/ improper seepage and Paper recycling dioxine, mercury, phenols, 2 2 3 12 wastes waste disposal groundwater styrene, mercury, pollution potassium dichromate
5.25 Non-Point Source Pollution Assessment
POTENTIAL POLLUTION INDUSTRY SOURCES PATHWAYS MHGTOTNOTES CONTAMINANTS RISK
Commercial & Personal Services Waste detergent, oil and Waste disposed to sewer/ Laundries & Dry Illegal/ improper Mostly within grease, organic wastes, waste collectors, air Pollution risk 2 2 2 8 Cleaning waste disposal municipal areas solvents, SS emissions
Petroleum hydrocarbons, Pollution risk Typical very large VOCs, BTEX, solvents, Improper/illegal disposal of Surface runoff/ Railway yards where poor 2 2 4 16 poor controlled fuels, oil and grease, lead, liquid & solid wastes seepage control areas PCBs
Car wash facilities Pollution risk mostly at filling Vehicle washing Waste detergent, oil, Improper/illegal disposal of Surface runoff/ where poor 1 1 3 3 stations. Depots centres, depots grease, solvents, SS liquid & solid wastes seepage control outside metro areas
Formaldehyde, radioactive material, Health risk photographic chemicals, Wash off, Health care Illegal dumping of wastes where poor 2 4 4 32 solvents, mercury, seepage, leaching control ethylene oxide, chemotherapy chemicals
5.26 Non-Point Source Pollution Assessment
POTENTIAL POLLUTION INDUSTRY SOURCES PATHWAYS MHGTOTNOTES CONTAMINANTS RISK Untreated overflow into Pollution risk, SS, nutrients, BOD, Untreated overflow, storm water, Wastewater health risk when micro-organisms, heavy improper/illegal sludge runoff/leaching 5 3 3 45 treatment operation/control metals disposal, digester gas from sludge is poor disposal, digester emissions
Pollution risk, TDS, nutrients, BOD, Poor control in Non-hazardous Seepage/leaching/ health risk when micro-organisms, heavy Waste material 2 2 4 16 many smaller waste disposal sites runoff operation/control metals operations is poor
Pollution risk, Hazardous waste Variety of disposed Waste containing ponds Seepage/leaching/ health risk when Normally well 2 4 3 24 disposal sites hazardous materials and disposal areas runoff operation/control controlled is poor
5.27 Non-Point Source Pollution Assessment
5.6 Discussion, evaluation and assessment
It was realised from the onset of the project that it would be very difficult to obtain quantitative data on Non-Point or Non-Point pollution arising from industries. The reasons are firstly that many industries are not aware of their contribution to Non-Point pollution, and secondly that industrialists in general would be hesitant to provide such information for fear that it might give rise to pressures from controlling bodies.
Our initial view was that the best way in which quantitative data on Non-Point industrial pollution could be obtained, would be from catchment studies where data could be derived from mass balances on pollution loads. In discussions with the project team, it was however, decided to follow a different approach by investigating individual industries and potential pollutants from these industries together with a risk assessment of Non-Point pollution. In hindsight it appears that the initial approach would have provided better information.
It is also our view that it would not serve much of a purpose to obtain detailed information from individual industries other than providing another list of potential pollutants. Almost all the industries that we had discussions with feel that the overall contribution to Non-Point pollution from current practices is much smaller than problems associated with treatment and disposal of effluents constituting point sources. The main concern over Non-Point pollution relates to accumulated waste materials. Industries as well as DWAF are aware of these problem areas and studies and monitoring programs are underway in many instances to remediate these problems. Examples include monitoring of boreholes in the vicinity of waste disposal sites, studies on in situ remediation of ground water, soil remediation studies, etc.
The most serious Non-Point pollution problems that industries have to deal with are of an historic nature. This means that the older the site the more and bigger are the problems. Previous waste disposal or storage practices resulted in larger or smaller quantities of waste material on site, which may have caused soil contamination and ground water pollution. Many of these are in different stages of investigation or active remediation.
Important factors that determine whether an industry could manage and control pollution, including Non- Point pollution include the following:
There must be an understanding by individual industries of the life cycle of contaminants generated during all activities. This includes understanding of:
- The sources of potential pollutants - Pathways of potential contaminants during all stages of transport / processing / manufacturing / waste management, etc. to determine movement and routes (precipitation, dissolution, evaporation, leaching, final fate, etc.) - Mass balances of potential contaminants to determine what and how much go where and what cannot be accounted for in order to identify Non-Point / Non-Point sources of pollution
- Pollution potential of substances that can end up in the environment
There must be active monitoring of processes and streams in the plant and during treatment in order to keep track of potential pollutants
When considering the contribution of industries to Non-Point Source Pollution, a distinction must be made between industries within municipal boundaries and those in industrial complexes (whether a single industry or group of industries).
5.28 Non-Point Source Pollution Assessment
Industries within municipal boundaries fall under control of municipal bylaws and mostly discharge effluents to the municipal sewer. Control of storm water pollution from industrial sites is also controlled by municipal bylaws. Local authorities have responsibility for collection, drainage and disposal of urban storm water, including storm water from industries within their boundaries and must therefore control pollution of storm water by industries. However, there is a big concern about the capacity of local authorities to control storm water contamination by Non-Point sources pollution from industries.
Most of the Non-Point sources pollution emanating from industries in municipal areas would be very difficult to account for since it is actually ‘hidden’ in urban storm water. Non-Point Source Pollution from these industries is mostly related to runoff resulting from rain events, making it even more difficult to quantify. There are however, also continuous sources of Non-Point Source Pollution that should be easier to identify and quantify such as streams leaving premises during dry spells. Possible causes of these include leakage from storage tanks, seepage, etc.
5.6.1 Onsite storage of material and solid waste
Industrial sites vary in size from small sites within the boundaries of a local authority to very large sites. A common feature of all industrial sites is that many different materials are stored on these sites, including raw materials, intermediates, final products, various wastes, etc. Such sites are therefore potential sources of pollution due to the possibility of leakages, spillages, or generally poor housekeeping. This may result in contamination of storm water through surface runoff and of groundwater through infiltration and seepage.
First order evaluation
Water and air pollution from onsite storage of materials and wastes on industrial sites cannot be prevented. There will always be some degree of leaking or spilling from liquid conveyance and storage systems. Rain or storm water can also be contaminated by stored materials and wastes if not properly covered or isolated. These leaks, spillages and contaminations enter storm water or infiltrate and contaminate ground water and in this way act as sources of Non-Point pollution. The extent of this form of Non-Point industrial pollution depends on a number of factors:
The mass of material or wastes stored on site. Obviously the larger the amounts, the larger the potential for pollution and the greater the demands for measures to prevent pollution..
The nature of material and wastes. The more reactive (volatile, degradable, leachable, etc.) the material is, the greater the pollution potential.
The level of housekeeping and control to minimise contamination. Most industries practise sound control and housekeeping measures which can prevent pollution by onsite storage to a large extent. However, there are also many industries where there is a lack of control and where contamination of storm water and soil is apparent and where Non-Point pollution occurs. This is not a problem of the nature or the size of the industry but a management problem.
The age and history of activities of the site. From discussions it appears that industries are to a large extent aware of the pollution potential of material and wastes stored on site and that they apply measures to minimise contamination. However, the pollution potential of ‘old’ deposits is a major cause for concern. The cost to clean up such old sites could be very high and for this reason some industries are hesitant to make information available on these types of deposits.
5.29 Non-Point Source Pollution Assessment
First order assessment
Onsite storage and disposal of material and solid waste is one of the main sources of Non-Point industrial pollution. Non-Point pollution arising from storage of materials is relatively small but the potential pollution from storage (disposal) of solid waste is very high. The large industries from which information was obtained, are well aware and conscious of this problem and all of them are to some extent implementing, or at least planning remediation measures to control pollution from these sources.
In our opinion the most reliable information on the actual contribution to surface water pollution by industrial complexes would be obtained from catchment studies in which upstream and downstream water quality can be monitored and correlated with point discharges. In the case of groundwater pollution water quality data from monitoring boreholes could provide data on the pollution level in the vicinity of the site compared to water quality further away.
The level of Non-Point pollution from industrial sites within municipal areas is very difficult to ascertain. A possible approach would be to monitor the heavy metal content of stormwater runoff and use that as an indicator of Non-Point industrial pollution.
5.6.2 Onsite disposal of effluents
In some cases industries store or dispose of effluents onsite. These could be effluents that are difficult or expensive to treat such as brines or concentrates that are stored (disposed of) in evaporation dams. This practice is controlled by DWAF but it remains a source of potential groundwater pollution.
First order evaluation
Water and air pollution from onsite disposal of effluents cannot be prevented but can be minimised through sound practises. The main problems relate to infiltration and ground water contamination from evaporation dams that are not properly designed or maintained and from overflows and spills from evaporation dams that are too small to contain discharges and rainfall.
The extent of this form of Non-Point industrial pollution depends on a number of factors:
The volume of effluents stored on site. Obviously the larger the volumes and the more dams/ponds, the larger the potential for pollution and the greater the demands for measures to prevent pollution..
The nature of material and wastes. Typically these effluents have a large pollution potential since they contain contaminants at high concentration.
The design of the holding facilities. Where the ponds are lined with impermeable linings and the capacity is large enough to prevent spilling. The pollution potential is relatively small.
The level of control and maintenance to minimise contamination. Most industries practise sound control and maintenance measures which can prevent pollution from onsite storage to a large extent
First order assessment
Onsite storage and disposal of effluent is an important source of Non-Point industrial pollution. The large industries, from which information was obtained, are well aware and conscious of this problem and all of them are to some extent implementing, or at least planning remediation measures to control pollution from these sources.
5.30 Non-Point Source Pollution Assessment
In our opinion the most reliable information on the actual contribution to surface water pollution by industrial complexes would be obtained from catchment studies in which upstream and downstream water quality can be monitored and correlated with point discharges. In the case of groundwater pollution water quality data from monitoring boreholes could provide data on the pollution level in the vicinity of the site compared to water quality further away.
5.6.3 Waste disposal sites
Industrial wastes emanating from production processes or from effluent treatment processes that cannot be recycled or reused are disposed of in landfill sites or in hazardous waste disposal sites. These sites could be managed by the industry (e.g. ash disposal) or by a private company. In all such cases the sites must comply with the minimum requirements for waste disposal sites administered by DWAF. Leakages and seepage from such sites can contribute to Non-Point pollution, mainly of groundwater.
Management of surface runoff and seepage from waste disposal sites must comply with DWAF requirements. These requirements include measures such as monitoring, collection and treatment of runoff and seepage and monitoring of water quality in monitoring boreholes in the vicinity of the site.
First order evaluation
Water and air pollution from waste disposal sites cannot be prevented but can be minimised by sound design, operation, control and maintenance. The main problem at waste disposal sites is to prevent leaching that can infiltrate and contaminate ground water and containment of contaminated runoff. Waste disposal sites that are properly designed and well managed and maintained have relatively small potential for pollution. However, older sites and those that are not well managed have a very serious potential for pollution because the material disposed of in such sites has a high pollution potential. A serious pollution threat comes from unregistered (illegal) disposal sites which are normally small facilities where limited control is exercised and into which a variety of wastes can be dumped.
First order assessment
The Non-Point pollution arising from well designed and operated waste disposal facilities is relatively small. There is however, potential pollution from disposal of solid and hazardous wastes into disposal sites that are older and not well controlled and maintained.
5.6.4 Atmospheric emissions depositing on water surfaces or soil and contaminating runoff
Atmospheric emissions from industries include gasses such as CO2, SO2, CH4, NOx, other volatile substances such as chlorinated hydrocarbons as well as particulate matter such as fly ash, soot, etc. An estimate can be made of the mass of combustion products emitted by industries, but it is rather difficult to calculate the actual mass of material deposited and the mass ending up and contaminating water sources.
5.7 Conclusions
The collection of Non-Point pollution data from industry has been difficult even though very good cooperation was given by most industry representatives. The overall impression is that the majority of larger industries are well aware of the potential problems associated with Non-Point pollution and that in most cases measures have already been implemented or are being developed to combat this problem. The main ‘hot spots’ in terms of Non-Point sources are the ‘historical’ sites where wastes had been disposed off over long periods of time into inadequately designed facilities and where adequate control
5.31 Non-Point Source Pollution Assessment was not exercised. These sites are very difficult and extremely costly to rehabilitate since the pollution effects have spread over large areas with contamination of groundwater the most serious problem. The extent of the pollution could not be quantified but from available information the pollution in some historic areas appears to be extensive.
5.8 Recommendations
In view of the fact that the main sources of potential Non-Point pollution are industrial complexes, it is recommended:
That a follow-up project be developed in cooperation with a selected industrial complex where catchment studies have been done and that the extent of Non-Point pollution from the complex be determined from such a study.
That further projects be developed in collaboration with selected priority industries to identify the main sources of Non-Point pollution within that industry and that further research be conducted to remediate such sites in the most cost-effective manner. Priority industries from Table 5.1 that could be considered include the chemicals manufacturing industry, petrochemical industry and fertilizer and agricultural chemicals industry. .
5.32 Non-Point Source Pollution Assessment
6 FIRST ORDER ASSESSMENT OF THE QUANTITY AND QUALITY OF NON-POINT SOURCES OF POLLUTION ASSOCIATED WITH THE POWER GENERATION SECTOR
6.1 Introduction
Degradation of quality of the environment results from contamination by Point as well as Non-Point or Diffused sources of pollution. Point source pollution refers to pollutants which enter the environment from a stationary location and sources are easily identifiable. Although point source discharges still produce some pollution, most of them are managed by imposing specific permit conditions.
Non-Point Source (NPS) pollution however, cannot be traced to a specific spot. Sources are diffuse and far more difficult to monitor and control. Non-Point sources are less visible sources of pollution, more widespread and introduce vast quantities of pollutants into the environment in a dispersed manner. Non- Point sources include
Atmospheric deposition
Contaminated sediments
Polluted run-off
Leaching from onsite waste disposal and
In-place contamination (such as leakages and spills).
In terms of pollutant loads, number of sources, aerial extent and number of contributors, Non-Point Source Pollution is a much larger and complex problem than point source pollution (DENR, 2005).
In order to manage and mitigate Non-Point Source Pollution an integrated approach is required, involving watershed management, land use planning, air pollution control and a variety of best management practices.
6.2 Scope of work
The electricity sector plays a central role in South Africa’s economy – as the supplier of a key input to the industrial, mining and commercial sectors, as an employer and as a service provider for households. The amount of electricity produced is driven by three primary factors: the increasing production of goods; an ever expanding population and a growing economy (DEAT, 2002).
Internationally it has become recognised that the contribution from Non-Point sources of pollution should also be addressed in order to achieve proper management of water quality. Uncertainty exists about the extent to which South Africa’s electricity sector is responsible for adverse impacts which are unaccounted or under-accounted for in the current regulatory regimes (Van Horen, 1996).
Although much is already known internationally, information published on Non-Point Source Pollution associated with power generation in the South African context is limited. Furthermore, synergy don’t exist with regards to available information since investigations they are based upon, were done at different times, under different circumstances, to different levels of detail and using different approaches.
The objectives of this chapter of the study are:
6.1 Non-Point Source Pollution Assessment
to compile the limited available information on Non-Point Source Pollution associated with power generation in South Africa into a consolidated overview that presents the current status of research in South Africa related to this topic
to use international information in an attempt to determine whether the present investment in research reflects the need in this regard, and
to make recommendations concerning sectors and topics that require research investment.
6.3 Main Environmental Regulatory Bodies overseeing the energy sector in South Africa
The Department of Minerals and Energy is the main regulatory body overseeing the energy sector in South Africa. Under the jurisdiction of this Ministry are several important entities which carry out the government's oversight role, including the National Electricity Regulator (NER), which is the regulatory authority over the electricity supply industry in South Africa, and the National Nuclear Regulator and the Council for Nuclear Safety, which are the regulatory agencies for the nuclear industry.
The monitoring and implementation of pollution control and waste management are the responsibility of The Departments of Environmental Affairs and Tourism; Water Affairs and Forestry; Health and Agriculture. Air quality in South Africa is controlled under legislation enacted in 1965. In terms of the local Act, a licence to operate a power generating plant is granted by the Chief Air Pollution Control Officer (CAPCO) of the Department of Environmental Affairs and Tourism (DEAT). CAPCO sets emission standards for power station particulate emissions on an individual basis. Similarly, before granting a licence for a new station, CAPCO must be satisfied that certain basic ambient air quality criteria will be met. Thus, DEAT has adopted certain air quality guideline values that are considered reasonable. These values are largely based on overseas experience with some modification for local conditions (Eskom Generation Communication GFS0026, 2003).
South Africa signed the United Nations Framework Convention on Climate Change (UNFCCC) in 1993, ratified it in August 1997, and acceded to the Kyoto Protocol in June 2001, ratified in 2005. Developed countries and economies in transition agreed to reduce their combined greenhouse gas emissions by an average of 5.2% compared with 1990 levels. The Kyoto Protocol allows any participating party with an emissions target to transfer units of emissions to another party if its 2008-12 emission levels are lower than its initially allocated amount. As a non-Annex I country, South Africa has no commitment to reducing emissions under the Kyoto Protocol.
The Department of Minerals and Energy (DME) White Paper on Energy Policy, issued in December 1998 (DME, 1998b), established the following priorities for the electricity supply sector:
to continue the electrification programme,
to restructure the sector to introduce greater competition,
to move to more cost-reflective tariffs, and
to promote energy efficiency through an integrated planning approach.
6.4 Overview of the power generating sector in South Africa
Electricity is a basic necessity for the economic development of a country. The survival of industrial undertakings and social structures depend heavily upon low cost and uninterrupted supply of electrical energy. Figure 6.1 below reflects a breakdown of the sources used for generation of electricity in South Africa (as of 2000).
6.2 Non-Point Source Pollution Assessment
Figure 6.1: Energy sources used for generation of electricity in South Africa (MWE, as of 2000, Energy overview of South Africa, 2005)
There are three main role players responsible for Power Generation in South Africa, namely
Eskom,
the Government (Municipal Power Stations) and
Public Private Partnerships (Independent Power Producers).
A summary of South Africa’s electricity generating plants is shown in Table 6.1.
Table 6.1: South Africa's Licensed Power Stations (as of 2000) (Energy overview of South Africa, 2005)
LICENSED EFFECTIVE* LOAD POWER PLANT LOCATION CAPACITY CAPACITY FACTORS (MWE) (MWE) (%)
Eskom Coal-fuelled Power Plants
Arnot Middelburg 1,980 1,858 56.1
Camden Ermelo 1,520 NonOp
Duvha Witbank 3,450 3,483 77.1
Grootvlei Balfour 1,130 NonOp
Hendrina Hendrina 1,900 1,884 75.9
Kendal Witbank 3,840 4,063 71.0
Komati Middelburg 906 NonOp
6.3 Non-Point Source Pollution Assessment
LICENSED EFFECTIVE* LOAD POWER PLANT LOCATION CAPACITY CAPACITY FACTORS (MWE) (MWE) (%)
Kriel Bethal 2,850 2,402 77.9
Lethabo Sasolburg 3,558 3,592 70.9
Majuba Volksrust 3,843 2,465 19.8
Matimba Ellisras 3,690 3,772 71.8
Matla Bethal 3,450 3,518 81.4
Tutuka Standerton 3,510 2,240 51.4
Total 35,627 29,277 67.2
Eskom Gas Turbine Power Plants
Acacia Cape Town 171 7 0.1
Port Rex East London 171 165 0.1
Total 342 172 0.1
Eskom Nuclear Power Plants
Koeberg Cape Town 1,840 1,810 82.1
Total 1,840 1,810 82.1
Eskom Hydroelectric Power Plants
Gariep Norvalspont 360 365 19.7
Vanderkloof Petrusville 240 245 33.1
Colleywobbles Mbashe River 42 42 36.2
First Falls Umtata River 6 6 35.5
Second Falls Umtata River 11 NonOp
Ncora Ncora River 2 2 49.6
Total 661 660 26.6
Eskom Pumped Storage Power Plants
Drakensberg Bergville 1,000 1,116 18.1
Palmiet Grabouw 400 426 22.0
Total 1,400 1,542 19.2
Municipal/IPP Coal-fuelled Power Plants
6.4 Non-Point Source Pollution Assessment
LICENSED EFFECTIVE* LOAD POWER PLANT LOCATION CAPACITY CAPACITY FACTORS (MWE) (MWE) (%)
Athlone Athlone 180 90 8.3
Kroonstad Kroonstad 30 NonOp
Swartkops Swartkops 240 NonOp
Bloemfontein Bloemfontein 102 30 8.1
AES Kelvin 'A' Johannesburg 180 90 50.3
AES Kelvin 'B' Johannesburg 420 260 55.2
Orlando Soweto 300 NonOp
Rooiwal Rooiwal 300 120 50.7
Pretoria West Pretoria 180 56 7.6
Total 1,932 646 40.9
Municipal Gas Turbine Power Plants
Athlone Athlone 40 29 0.2
Johannesburg Johannesburg 176 102 0.5
Port Elizabeth Port Elizabeth 40 21 0.0
Pretoria West Pretoria West 24 NonOp
Roggebaai Roggebaai 40 36 0.0
Total 320 188 0.3
Municipal Hydroelectric Power Plants
Ceres Ceres 1 <1 5.1
Lydenburg Lydenburg 2 2 34.2
Piet Retief Piet Retief 1 1 68.5
Total 4 3 36.9
Municipal Pumped Storage Power Plants
Steenbras Gordon's Bay 180 176 15.5
Total 180 176 15.5
Industrial Bagasse/Coal-fuelled Power
Plants
Tongaat-Hulett Amatikulu Amatikulu 12 10 52.3
6.5 Non-Point Source Pollution Assessment
LICENSED EFFECTIVE* LOAD POWER PLANT LOCATION CAPACITY CAPACITY FACTORS (MWE) (MWE) (%)
Tongaat-Hulett Damali Damali 13 7 48.0
Tongaat-Hulett Felixton Felixton 32 24 42.5
Tongaat-Hulett Maidstone Mill Maidstone 29 20 37.7
Transvaal Suiker Ltd. Malelane 20 19 46.6
Total 105 80 43.9
Industrial Coal-Fueled Power Plants
Sasol Synthetic Fuels Secunda 600 629 92.8
Sasol Chem Ind. Sasolburg 128 140 57.7
Total 728 768 86.4
Industrial Hydroelectric Power Plants
Friedenham Friedenham 3 2 73.0
Total 3 2 73.0
* Effective Capacity differs from Licensed Capacity due to deratings, improvements, and/or usage trends ** based on Effective Capacity. n/a – not available;
IPP – Independent Power Provider
NonOp – non-operational (shut down or in stand-by mode)
Generation and transmission of electricity in South Africa are dominated by the parastatal utility, Eskom, which owns and operates 92 per cent of generation capacity, with municipalities and private generators owning six and two per cent, respectively (Spalding-Fecher and Matibe, 2003).
The nominal generating capacity for Eskom is 42 011 MW, with a generating capacity of 4201 MW in reserve and under construction. Eskom’s generation mix is shown in Figure 6.2 below:
6.6 Non-Point Source Pollution Assessment
Figure 6.2: Percentage make up of Eskom Electricity Production (2003 Van der Riet M et al., 2004)
The coal-fired and nuclear power stations are the only power stations that are fully operated at all times. These stations are referred to as ‘base-load’ power stations, which operate on a 24-hour basis to ensure a constant supply of energy for normal daily consumption.
Hydroelectric and pumped storage schemes are only used during South Africa’s peak periods, such as the early hours of the morning and evenings. Gas-turbine power stations are only used during extreme emergencies due to their very high operating costs.
During this study, it was found that most of the power stations operated by municipalities are no longer profitable as municipally run entities due to existing technology as well as lack of capital. Most of these stations, which could in the past generate up to 180 MW, are at present only re-fired in winter times to generate approximately 90 MW.
The Kelvin Power Station in Johannesburg was recently successfully converted to a Public Private Partnership. A decision has also been taken by the City of Cape Town to convert the Athlone power station to either an Independent Power Producer or a Public Private Partnership which will only produce peak power and will have a long term purchase agreement with Cape Town.
6.5 Electricity demand forecast
The White Paper on Renewable Energy (2003) set a target of 4% of projected electricity demand for 2013 (DME 2003b). Figure 6.3 depicts a forecast of the expansion of electricity generation capacity, grouped by plant type (Davidson et al., 2006). The current development trends show that existing power stations will continue to provide a substantial part of capacity up to 2025. Investment in new capacity is directed towards the recommissioning (‘de-mothballing’) of three coal-fired power stations (Camden, Grootvlei en Komati Power Stations), building new pulverised coal stations, open cycle gas turbines (diesel-fuelled) as well as combined cycle gas, and some new pumped storage (Davidson et al., 2006).
6.7 Non-Point Source Pollution Assessment
70
60
50
40 GW 30
20
10
0 2005 2007 2009 2011 1013 2015 2017 2019 2021 2023 2025
Existing coal Nuclear PWR Bagasse Diesel gas turbines Hydro Pumped storage Imported electricity Mothballed coal New Coal New OCGT diesel New CCGT New FBC
Where: PWR =Pressurized Water Reactor; OCGT = open cycle gas turbine;
CCGT = combined cycle gas turbine; FBC = fluidised bed combustion
Figure 6.3: Long-term electricity demand forecast for South Africa (Giga Watts)
At present, the commercial exploitation of South Africa’s renewable energy sources is limited, but it is clear that the cost of renewable energy will continue to decline as the technologies mature.
6.6 Coal fired power generation
South Africa’s generating technology is based largely on coal-fired power stations. Eight of the ten operational coal-fired power stations in South Africa are situated in Mpumalanga (Figure 6.4).
6.8 Non-Point Source Pollution Assessment
Figure 6.4: Power Stations and their locations in South Africa
6.9 Non-Point Source Pollution Assessment
The process of coal-fired power generation can be presented by the block diagram shown in Figure 6.5.
Evaporation & drift loss
COOLING WATER TreatmentC EFFLUENT hemicals SYSTEM
BOILERS, TURBINES, Chemicals Potable Water CONDENSORS
RAW CLARIFIERS DEMIN Raw WATER AND FILTERS WATER Ion Exchange & PRODUCTION Regen Effluent Water
Clarifier Sludge Stack Gases
COAL BOILER EMISSION STOCKPILE FURNACE CONTROL Effluent: Ash
Bottom Fly Conditioning
ASH DISPOSAL
Surface Runoff
EFFLUENT Leachate MANAGMENT
Figure 6.5: Process for coal-fired power generation.
A summary of the inputs and outputs of coal fired power generation is shown in Figure 6.6
Coal Electricity
Chemicals/ COAL COMBUSTION Emissions Materials to AIR
Water Emissions
to WATER
Energy COAL COMBUSTION PRODUCT and Fuel Emissions to LAND
Figure 6.6: Inputs and outputs of coal fired power generation
6.10 Non-Point Source Pollution Assessment
6.6.1 Coal Mining and Preparation
Coal has been, and currently still is, the cornerstone of the South African energy economy (Mangena and Brent, 2006).
South Africa has 19 official coal fields. The Mpumalanga province accounts for 83% of South African coal production, while Free State (9%) Limpopo (7%) and KwaZulu-Natal (1%) also house production facilities (www.eia.doe.gov/emeu/cabs/safrica.html).
Anglo American’s Anglo Coal (Anglo), BHP Billington’s Ingwe Coal (Ingwe), domestic mining firms Eyesizwe Coal (Eyesizwe), Kumba Resources (Kumba), Sasol Mining (Sasol), and Swiss-based Xstrata Coal South Africa (XCSA) are responsible for the majority of South Africa’s coal production (Figure 6.7).
Figure 6.7: Coal Production in South Africa in 2003 (Source: Minerals Bureau) Suppliers of coal (i.e. coalmines or collieries) sell various grades to a variety of consumers. Local petrochemical and energy industries rely heavily on low-grade coal as feedstock. High-grade coal, in turn, is exported to developed countries (Mangena and Brent, 2006). The various sectors of the South African coal market are shown in Figure 6.8.
6.11 Non-Point Source Pollution Assessment
Figure 6.8: Sectors of the South African coal market in 2003 (Source: Minerals Bureau)
The inputs and outputs of coal mining and preparation can be presented by the block diagram shown in
Figure 6.9.
Coal Reserves Water Fuel
Coal Mining : Underground /
Surface Mining Coal Cleaning
Dust & Waste Rock / Leachate (Acid Mine Coal Combustion Water Overburden Drainage – Low pH, Discard
Products high concentration of lt d t l )
Figure 6.9: Inputs and Outputs of Coal Mining and Preparation
6.12 Non-Point Source Pollution Assessment
The environmental impacts associated with coal mining and preparation is variable, as the mining methods used to extract coal, opencast of underground techniques, result in different environmental impacts (Mangena and Brent, 2006). Environmental impacts associated with coal mining and preparation are discussed in the section addressing Non-Point Source Pollution associated with the mining industry.
6.6.1.1 Composition of South African coals
South Africa's coal reserves are mainly bituminous, with a moderate to high ash content (20- 30%) and low sulphur content (average 0.6-1.2%). Practically all the elements of the Chemical Periodic Table are present in coal. According to their different contents, these elements can be divided into three groups:
major elements (C, H, O, N, S), whose amounts are above 1000 ppm;
minor elements, which include coal mineral matters (Si, Al, Ca, Mg, K, Na, Fe, Mn, Ti) and halogens (F,Cl, Br, I), present in concentrations between 100 and 1000 ppm; and
trace elements, which are the constituents with concentration below 100 ppm.
Chemical Properties of South African coal presented in Table 6.2 were reported by Stuart et al. (1997).
Trace elements present in different South African coals (Table 6.3) were reported in a newsletter by
Australian Coal Research Ltd in August (1996) as well as by Wagner and Hlatswayo (2005)
The classification of trace elements by level of concern (Table 6.3) is based on the potential hazards of these elements to biological systems (Clarke and Sloss, 1992), and does not imply that their presence in coal constitutes a health risk. It rather takes into account the potential for these elements to impact the environment through their distribution in waste products from combustion (Australian Coal Research
Ltd., 1996).
The radioactivities of all coals were similar and the low levels of uranium, thorium and natural radionuclides are not significantly greater than the average levels in the earth's crust (Australian Coal
Research Ltd., 1996).
Table 6.2: Chemical Properties of Coal (Stuart et al., 1997)
COAL PROPERTY UNDERGROUND (%) OPENCAST(%)
Inherent Moisture 2.69-3.86 3.37-3.90
Ash 23.30-25.34 27.98-30.52
Carbon 57.03-59.22 51.22-53.64
Hydrogen 2.73-3.21 2.55-3.04
Nitrogen 1.23-1.43 1.13-1.33
Total Sulphur 0.77-1.00 0.64-1.15
Carbonate(as CO2) 2.01-2.53 1.65-2.24
Oxygen 6.13-7.73 6.39-8.55
6.13 Non-Point Source Pollution Assessment
Gross Calorific Value 22.24-22.82 19.87-20.79 (MJ/Kg)
Table 6.3: Trace elements present in different types of South African Coal (Australian Coal Research Ltd., 1996 ; Wagner and Hlatshwayo, 2005)
SOURCE : AUSTRALIAN COAL RESEARCH LTD. 1996 SOURCE : WAGNER &
(HIGH GRADE SOUTH AFRICAN COALS)) HLATSHWAYO, 2005
Coal 1 Coal 2 Coal 3 Coal 4 Coal 5 Coal 6 Coal 7 Coal 8 Coal 9
Trace Elements of MAJOR concern (mg/kg)
As * 1.2 1.4 3.0 2.2 1.8 2.1 3.74 2.84 2.36
B** 35 27 60 34 50 30
Cd*** 0.10 0.08 0.19 0.06 0.12 0.14 0.29 0.47 0.16
Hg 0.089 0.11 0.10 0.13 0.061 0.10 0.22 0.16 0.18
Mo*** 1.3 0.95 1.5 1.1 1.1 1.1 1.16 1.27 1.1
Pb*** 10 7.6 12 7.6 9.5 12 7.44 6.61 5.92
Se* 0.8 0.38 1.3 0.50 1.1 0.50 0.98 0.61 1.0
S(%)** 0.43 0.58 0.59 0.66 0.51 0.61 0.96 0.87 1.0
Trace Elements of MODERATE concern (mg/kg)
Cr ** 22 22 34 28 24 26 53.8 59.8 46.5
Cu** 7.8 9.5 18 11 7.2 11 13.0 12.8 14.3
Ni*** 10 6.5 15 13 21 6.5 20.0 23.5 16.0
V** 18 16 35 32 25 23 35.0 34.0 33.0
Zn** 5 12 29 10 12 16 10.1 13.3 15.5
F 135 185 270 240 305 240
Cl 30 35 90 40 50 30
Trace Elements of MINOR concern (mg/kg)
Ba** 318 336 377 381 291 325
Co** 4.3 3.5 7.3 5.5 7.8 6.7 7.12 7.3 7.2
Mn** 47 51 93 58 74 47 106.2 112.1 106.6
Sb*** 0.17 0.18 0.80 0.23 0.26 0.19 0.2 0.2 0.2
6.14 Non-Point Source Pollution Assessment
SOURCE : AUSTRALIAN COAL RESEARCH LTD. 1996 SOURCE : WAGNER &
(HIGH GRADE SOUTH AFRICAN COALS)) HLATSHWAYO, 2005
Coal 1 Coal 2 Coal 3 Coal 4 Coal 5 Coal 6 Coal 7 Coal 8 Coal 9
Sr** 267 355 347 412 320 403
6.15 Non-Point Source Pollution Assessment
Radioactive Elements
U (mg/kg) 1.7 2.3 1.8 2.0 1.8 2.1
Th (mg/kg) 7.3 6.7 5.4 6.6 6.6 7.7
Th-230 (bq/kg) 46 19 62
Po-210(bq/kg) 42 16 55
Rn-222(bq/kg) 42 18 56
Total radio 986 740 1325 activity(bq/kg)
Where: COALS 1-6 : * Hydride Generation – atomic fluorescence spectrometry ** Inductively coupled plasma atomic emission spectrometry ***Inductively coupled mass spectrometry Mercury was determined by Atomic absorption spectrometry COALS 7-9: Analysis conducted by USGS. JH Bullock Jnr, RB Finkelman (2002-2003)
6.6.2 Coal Combustion
Combustion is defined as the rapid chemical combination of oxygen (O2) with the combustible elements of the coal, which are the organic components or organic associated components. Figure 6.10 presents the inputs and outputs of coal combustion.
Leachate
Coal COAL STOCKPILE Surface Runoff
Coal
Fly Ash Pre-heated COAL Bottom Ash Air COMBUSTION Boiler Blowdowns /BOILERS/ Demin EMISSIONS Stack gases(SO2, CONTROL NOx,CO2,Particulates, Metals)
Figure 6.10: Inputs and outputs of Coal Combustion
Coal is crushed, pulverized and injected into a combustion chamber where it is mixed with pre-heated air and ignited (Eskom Generation Communication GFS 0011, 2006). The chemical and physical processes
6.16 Non-Point Source Pollution Assessment occurring during the combustion (and gasification) of coal are complex. The inorganic fraction of the coal is converted to fly ash or bottom ash. In addition, the sulphur in the source coal is oxidized to SO2 and the nitrogen to nitrogen oxides (NOx). Trace elements are neither created nor destroyed during combustion, but the environment they are subjected to can cause trace elements to be distributed among different particle sizes and species. The trace elements introduced into a combustion system as part of the coal feeds can only exit the combustion system through a finite number of pathways: (1) bottom ash, (2) fly ash and (3) flue gas.
Many of the trace elements present in the feed coal are partially or completely vaporized during combustion. (Figure 6.10).
120
100
80 Hg Pb 60 Cu Vapour % 40 As
20
0 550 750 950 1150 Temperature (C)
Figure 6.11: Percent Vapour Phase as a Function of Temperature for Selected Trace Elements (Martinez-Colon,2003)
Although most elements are volatilised in the furnace they are adsorbed onto ash particles as the flue gases cool in the rear portion of the boiler. The degree of volatility of each element and the compounds it forms determines how they are partitioned between the various solid residues in the flue gas (fly ash) and whether any is emitted in the vapour phase (DTI Report, 2003). As volatility is so important in determining trace element behaviour, many researchers have proposed grouping elements based on their relative volatility and subsequent partitioning during combustion and gasification (Figure 6.12). These groupings are largely consistent, but partitioning behaviour can vary between different combustion systems and different operating systems (DTI Report, 2003).
6.17 Non-Point Source Pollution Assessment
BOILING PTS, ºC INCREASING
VOLATILITY
F -188.1 CLASS III
Cl -34.1 Volatized and Emitted fully in the Vapour- Se 217 phase. Not enriched on the fly ash
SeO2 317
Hg 357
As2O3 465 CLASS II As 613 Enriched in the fly ash
MoO3 795 and depleted in the bottom ash Zn 907
Sb2O3 1155
B2O3 1800 CLASS I CoO 1800 Equally Distributed
Mn 1960 between bottom ash and fly ash Cu 2570
Ni 2730
Co 2870
Cr2O3 3000-4000
Mo 4660
Figure 6.12: Categorization of trace elements based on volatility behaviour (Xu et al., 2003)
Based on volatility behaviour, the majority of trace elements released are generally associated with particulate material. As such, the vast majority of trace elements can be captured efficiently by particulate control equipment (DTI Report, 2003). More volatile elements however, such as selenium and mercury, can be emitted partially in the vapour phase and might not be captured by particulate control devices.
6.18 Non-Point Source Pollution Assessment
It is important to appreciate that physical processes related to furnace design, temperature profiles and other factors such as coal and flue gas composition, particulate size, composition and loadings affect the overall distribution of trace elements.
Emission Control Emission Control systems have a significant effect on the quality and quantity of combustion emissions. Prior to leaving the stack, fly ash can be removed from flue gas by electrostatic precipitators, baghouses or other collection systems, such as mechanical dust collectors. In addition to these, electric generators can be equipped with flue gas desulfurization (FGD) units or wet scrubbers for sulphur control.
All of Eskom's coal-fired power stations are fitted with electrostatic precipitators to remove dust and particulates. One of the municipal power stations, the Rooiwal Power Station, was fitted with bagfilters in 2005.
6.6.2.1 Non-Point Source Pollution associated with Coal Combustion Air Pollution Air pollution is categorised as a diffuse source of water pollution. In this section particular attention was paid to atmospheric emissions which often settle out onto land surfaces and are washed into nearby watercourses during rain events.
The impact of air pollution on water quality is an issue of concern for all water users since any degradation in water quality affects the water’s suitability for use (DWAF, 1996). Pollutants are moved around the world by air and water, as well as by living organisms. Air quality impacts are governed by the distribution of air pollutants, with impacts being sometimes experienced some distance from the pollution source depending on air movements as well as climatic and meteorological conditions. The possibility of negative impacts of air pollution on the environment in South Africa was first highlighted at a workshop in Pretoria in October 1987 (Walmsley and Olbrich, 1989). The workshop addressed "the air pollution situation and its implications in the Eastern Transvaal Highveld". This workshop was followed by a second workshop in Pretoria in August 1988. The second workshop focused on reviewing research and identifying future research. One of the identified research needs was to determine the impact of air pollution on surface water quality.
Pollutants emitted into the atmosphere (such as particulates) can have a significant impact on ground- level objects and surface water sources, since they are eventually deposited to the surface through processes of wet (precipitation) and dry (as particles) deposition (Piketh and Annegarn,1994) as shown in Figure 6.13.
6.19 Non-Point Source Pollution Assessment
Figure 6.13: Conceptual Model of Atmospheric Deposition (Piketh and Annegarn,1994)
Two basic physical forms of air pollution exist (Eskom Generation Communication GFS 0025, 2005):
Particles
Particles include small, discrete masses of solid or liquid matter such as dust, smoke, mist and fly ash which float in the air or settle very slowly
Gases
Gases are widely separated molecules in rapid motion such as sulphur dioxide, etc.
Air pollutants can be classified as primary or secondary pollutants (Eskom Generation Communication GFS 0025, 2005):
Primary pollutants are pollutants emitted into the atmosphere, directly from identifiable sources and are found in the atmosphere in the same chemical form as when emitted from source.
Secondary Pollutants are formed as a result of chemical reactions involving primary pollutants in the atmosphere.
Table 6.4 presents a summary of major air pollutants generated during coal-fired power generation operations and the effect on the environment. These are also called criteria pollutants (pollutants which are widespread, common pollutants which have been shown to be harmful to human health and welfare).
6.20 Non-Point Source Pollution Assessment
Table 6.4: Air pollutants emitted to the atmosphere during coal-fired power generation operations.
EFFECT POLLUTANT SYMBOL FORM TYPE PROPERTIES SOURCES ENVIRONMENT / HEALTH
Coal and oil combustion (contribute to 30% of emissions in the world) Causes acid rain, Colourless Sulphur Primary and corrosion and SO Gaseous compounds x Secondary Iron and copper respiratory Irritating odour smelting problems
Motor vehicles and Domestic combustion
Includes Combustion several gases processes with various Nitrogen Primary and Photochemical NO Gaseous properties Natural sources, compounds x Secondary smog e.g. forest and Nitrogen veld fires, rivers dioxide is toxic and lightning
Combustion processes Enhances global Carbon dioxide CO2 Gaseous Primary Colourless Natural sources, warming. e.g. forest and Odourless veld fires, rivers and lightning
Open cast mining operations Introduces toxins, heavy metals, Steel e.g. mercury, manufacturing TSP (Total Small pieces of lead, arsenic to Particulate Primary and suspended Particulate liquid or solid the environment matter Secondary Power Stations particulates) matter Contributes to Agricultural health problems processes and lung damage Milling plants
Industrial Mostly derived Activities Accumulates in from ore- aquatic food bearing Mining Mercury, Lead Hg, Pb Particulate Primary chains exposing minerals Operations humans to health effects. Power Generation
6.21 Non-Point Source Pollution Assessment
In order to protect human health and wellbeing, and prevent undesirable impacts on the environment, National Ambient Air Quality Guidelines have been set for these pollutants (Eskom Generation Communication GFS 0025, 2005).
The industrialised Highveld region 1400-1700 m above sea level in the Mpumalanga Province is one of the major source areas for industrially related atmospheric emissions since the province is the main coal producing region of South Africa and houses the majority of coal fired power plants, major petrochemical plants, smaller industries and smoldering discard coal dumps.
Eskom has been operating an ambient air quality monitoring network since the 1980s. This network (Figure 6.14) includes strategic sites and sites in the immediate vicinity of certain power stations. The network provides strategic information on long-term trends in air quality from various sources on a national and regional scale.
Figure 6.14: Eskom ambient air quality monitoring network (Zunckel et al., 2004).
All sites, with the exception of two, are equipped to monitor SO2, NOx, ozone (O3), fine particulate matter (FPM) and the relevant meteorological parameters comprising wind speed, wind direction and ambient temperature. The remaining two are equipped to monitor SO2, FPM and meteorological parameters (Eskom Annual Report, 2005). All monitoring equipment is calibrated against National Meteorological Laboratory standards in a South African National Accreditation Systems (SANAS) accredited laboratory (Eskom Annual Report, 2005).
Atmospheric emissions of Particulate Matter (TSP), SO2 and NOx (expressed as kg/MWh generated) related to coal fired power plants are presented in Figure 6.15.
6.22 Non-Point Source Pollution Assessment
20
18
16
14 Eskom 12 Kelvin 10 Rooiwal
kg/MWh 8 Pta West Athlone 6
4
2
0 TSP Emissions NOx Emissions SO2 Emissions
Figure 6.15: Particulate (TSP), SO2 and NOx Emissions: Municipal (Data for 1994) and Eskom (Data for 2005) Coal Fired Power Plants
(More recent data for municipal power stations could not be obtained.)
Results for global anthropogenic emissions of mercury (Pacyna and Munthe, 2004) are presented in Figures 6.16 and 6.17.
Although mercury (Hg) concentration in coal is usually extremely low, significant attention is internationally focused on its emission because its capture by treatment systems is problematic, and moreover, it is highly toxic to human health and it bioaccumulates.
Mercury shows extremely complex behaviour on combustion .The boiling point of mercury is 360°C and therefore at typical combustion temperatures of around 1500°C it is completely volatilised. The amount of mercury remaining in the vapour phase at the stack can vary widely, depending on flue gas temperatures, cooling rates, coal type and combustion conditions. Whatever the form of mercury in the coal, elemental mercury is assumed to be formed immediately on combustion, whilst subsequent reactions with various flue gas species can result in some of the elemental mercury being oxidised to Hg 2+ (DTI Report, 2003).
The fate of mercury emissions depends on various factors, including the form (species) emitted, stack height, topography and meteorology (DTI Report, 2003):
elemental mercury is believed to remain in the atmosphere up to one year. It can travel globally before undergoing transformation (although some deposits locally/regionally);
particle-bound mercury can deposit over a range of distances; and
oxidized mercury (also called ionic or reactive gaseous mercury (RGM)), predominantly in water soluble forms, may deposit from the atmosphere quickly and locally.
6.23 Non-Point Source Pollution Assessment
Figure 6.16: Global Anthropogenic Emissions of Mercury (metric tonnes/year) (Pacyna and Munthe, 2004)
Figure 6.17: Anthropogenic Emissions of Mercury : Distribution by Industrial Sector (Pacyna and Munthe, 2004)
Atmospheric Deposition Research (Wells et al., 1996; Held and Mphepya, 2000) indicate that the Mpumalanga Province accounts for 91% of SA’s NOx emissions (1 million tons/year) and is one of the major source areas for industrially related sulphur and particulate (0.3 million tons/year) emissions (Zunckel et al., 1991). Emission densities are among the highest in the world.
Research (Wells et al., 1996; Held and Mphepya, 2000) further indicate that more than 60% of the NOx emissions in the Highveld region occur from stacks taller than 200 m, and, in fact, most of these
6.24 Non-Point Source Pollution Assessment emissions originate from 8 large coal fired power plants and a synthetic fuel (from coal) processing complex (Held et al., 1999).
The meteorological situation over SA is typically dominated by a subtropical high associated with weak pressure gradients, leading to an accumulation and re-circulation of pollutants (Held et al., 1994 ; Garstang et al., 1996), as well as to the formation of several inversion layers that limit the vertical dilution of air pollution (Zunckel et al., 2000).
Dry and wet deposition of nitrogen and sulphur was examined using air and precipitation chemistry observations at four monitoring points: Amersfoort, Louis Trichardt, Palmer and Elandsfontein (Figure 6.18). These sites represent industrial (Amersfoort & Elandsfontein) and background (Louis Trichardt & Palmer) environments.
Figure 6.18: Indication of the relative position of monitoring sites Amersfoort, Louis Trichardt, Elandsfontein and Palmer (Zunckel et al., 2004).
Nitrogen deposition
The atmosphere is a critical environment for the nitrogen (N) cycle. N is converted from N2 to reactive N
(e.g., NOx, NH3) through worldwide energy and food production. A large portion of N is emitted into the atmosphere as NOx and NH3. NOx and NH3 are deposited to the earth’s surface by means of wet and dry deposition resulting in environmental impacts as N cascades along its biogeochemical pathway. In sequence, an atom of N mobilized as NO in the atmosphere can first increase ozone concentrations, then decrease atmospheric visibility and increase concentrations of small particles, and finally increase precipitation acidity. Following deposition to terrestrial ecosystems, that same N atom can increase soil acidity, decrease biodiversity, and either increase or decrease ecosystem productivity
Figure 6.19 shows that the total annual deposition of nitrogen varies from 15 kg N/ha.yr at Amersfoort (industrial area), to 9 kg N/ha.yr at Louis Trichardt (rural dry savannah) (Galy-Lacaux C et al., 2003). These values correspond well with that of Lowman and Scholes (2002) who estimated a deposition rate of 13.1 kg N/ha.yr for grasslands.
6.25 Non-Point Source Pollution Assessment
Figure 6.19: Wet and dry atmospheric nitrogen deposition in Africa (Galy-Lacaux et al., 2003).
At Amersfoort, situated close to major industrial emissions on the South African Plateau, wet deposition accounts for 63% of the total deposition of nitrogen and dry deposition accounts for 37% of the total deposition of nitrogen (Galy-Lacaux et al., 2003). At Louis Trichardt, 41% of the total nitrogen deposition is being delivered with the rain (Galy-Lacaux et al., 2003). The large difference in total deposition load clearly illustrates the influence of industrial activities on the central Mpumalanga Highveld.
Sulphur Deposition Annual mean sulphur dioxide concentrations reported at various Eskom monitoring points is shown in Figure 6.20.
Figure 6.20: Sulphur emission rates in kton S/a for the Mpumalanga Province (Zunckel et al., 1991)
6.26 Non-Point Source Pollution Assessment
2- Zunckel et al. (2002) measured sulphur dioxide (SO2) and sulphate (SO4 concentrations at two deposition monitoring sites (Palmer and Elandsfontein). Zunckel et al. (2002) reported that the maximum
SO2 dry deposition flux occurs on the central highveld in both summer and winter and decreases rapidly with increasing distance from the source region in correspondence with decreasing SO2 concentrations
(Zunckel et al., 2002). In the 150 km between Elandsfontein and Palmer the SO2 deposition flux decreased by 65% in winter and 86% in summer. Total annual dry deposition flux at two monitoring sites, Palmer (background site) and Elandsfontein (industrial site), measured over the period of one year are presented in 6.21.
Background Site (3.28 kg S/ha.yr) Industrial Area (23 kg S/ha.yr)
Dry Deposition 9% Wet Deposition 43%
Dry Wet Deposition Deposition 57% 91%
Figure 6.21: Wet and dry sulphur deposition in South Africa (Zunckel et al., 2002).
The proportional contribution of different sources to sulphur dioxide pollution in the Mpumalanga Highveld is shown in Figure 6.22.
Figure 6.22: Proportional contribution of different sources to sulphur dioxidepollution in Mpumalanga (Whyte et al., 1995).
Scorgie et al. (2002) reported a total sulphur deposition rate of 8500 tons per annum attributed to Eskom for the Grootdraai Dam catchment based on 1999 emission rates. The potential sulphate contribution as
6.27 Non-Point Source Pollution Assessment result of Eskom emissions could be quantified as 47.7 mg/kg. Sulphate concentrations for the Grootdraai 2- Dam are presented in Figure 6.23 below. The 2004 sulphate concentration of 26.11 mg/kg as SO4 is well below what is estimated to be the potential. The reason why these elevated concentrations don’t show in surface water concentrations is well documented in the theory of sulphate reduction in an anaerobic environment.
GROOTDRAAI DAM Water Quality - Sulphate (mg/kg)
40
y = 0.4969x - 967.51 R2 = 0.4974
30
20 Sulphate (mg/kg) Sulphate
10
0 1980 1985 1990 1995 2000 2005 Date
Figure 6.23: Sulphate concentrations for the Grootdraai Dam (Data supplied by Eskom)
Fine Particulate matter Fine particulate matter (very fine fly ash) emitted represent ±1% of the ash of which only 2% is soluble. Approximately 5000 tons particulates are emitted to the atmosphere per annum. The bulk soluble contaminant of particulates (fly ash) is essentially calcium oxide which hydrolyses to form calcium hydroxide. Calcium hydroxide will react with inorganic acids to form a salt plus water or in the absence of acids with bicarbonates to form carbonates. Carbonate, chloride, sulphate, nitrate, sodium, potassium, calcium and magnesium are contributing ions to total dissolved salts (TDS) (Bothma, 1998). Increased total dissolved salts (TDS) and electrical conductivity (EC) concentrations in water reflect salinity. It should be noted that salinisation is commonly the result of a combination of point and diffuse source input.
Molebatsi (2002) investigated the impact of atmospheric emissions from the Majuba power station on salinity and acidity of surface water. The study investigated the possibility of occurrence of salinity and acidity problems in waters within a 31 km radius of the Majuba power station. The study was conducted over a period of three years and the physical, chemical and biological quality of surface water was assessed at six sampling sites (4.7 km, 7.5 km, 9.2 km, 18 km, 24 km and 30.8 km away from power station). Results showed that emissions due to coal-fired power generation affect the quality of surface waters only to a minor extent. Two of the six sampling sites closest to the power station showed salinity problems which were indicated by acidity levels as well as total dissolved salt concentrations (Molebatsi, 2002). Water quality at the four remaining sampling sites were of acceptable quality.
6.28 Non-Point Source Pollution Assessment
Acidity in Rain Acid rain, or more accurately, the modification of rainfall chemistry by pollution, is a regional phenomenon. Rains in the South African interior seem to be naturally acidic. However, the acidity balance is altered to some extent by contaminants. Carbon dioxide, sulphur dioxide, nitrous oxides and chlorine may be converted through a series of complex chemical reactions, into carbonic acid, sulphuric acid, nitric acid or hydrochloric acid, increasing the acidity of the rain or other type of precipitation onto surfaces such as land and water. This process is referred to as acidic deposition or acid rain, which causes surface waters and soils to become more acidic (Walmsey and Olbrich, 1989). Acidity of surface water is indicated by a number of chemical water quality parameters. These parameters include pH, sulphate and aluminium concentrations (DWAF, 1997). A low pH value (i.e. less than 6 pH units) indicates acidification. The severity of acidification rises with a decrease in pH value.
Rainfall chemistry parameters are measured as mean ion concentrations of seven anions and six cations (Table 6.5).
Table 6.5: Rainfall chemistry parameters
ANIONS CATIONS
2- Sulphate (SO4 ) + Ammonium (NH4 ) - Nitrate (NO3 ) Calcium (Ca2+) Chloride (Cl-) Sodium (Na+) 3- Phosphate (PO4 ) Potassium (K+) Fluoride (F-) Hydrogen (H+) - Acetate (CH3COO ) Magnesium (Mg+) Formate (HCOO-)
Acidity in rain was monitored as part of the Kiepersol project. Rain event data up to 1999 were captured at various monitoring sites (Figure 6.24) including Amersfoort, Ermelo, Ladysmith, Louis Trichard, Piet Retief, Vryheid and Warden.
6.29 Non-Point Source Pollution Assessment
Figure 6.24: Acid rain monitoring sites
Eskom, as of 1995, has supported the International Global Atmospheric Chemistry (IGAC) programme DEBITS (Deposition of Biogeochemically Important Trace Species) for Africa IDAF (IGAC DEBITS AFRICA). Experimental data on the precipitation chemistry focussing on 2 locations in the semi-arid savanna of South Africa, i.e. Amersfoort and Louis Trichardt, is presented by Mpheya et al. (2004).
Table 6.6 presents the volume-weighted mean chemical composition, the annual wet deposition and the averaged pH calculated from the volume weighted mean concentration of H+ for Amersfoort and Louis 2− + 3- + Trichardt . The most abundant ions in precipitation at Amersfoort is the SO4 ion, H , NO , NH4 , and Ca2+, respectively (Table 6.6). These five ions represent 79% of the ionic content of the rainwater samples. At Louis Trichardt, the most abundant ions present in precipitation is also SO42−, H+, Ca2+ , + 3- NH4 and NO , respectively (Mpheya et al., 2004).
6.30 Non-Point Source Pollution Assessment
Table 6.6: Volume-weighted mean chemical composition of precipitation and deposition at Amersfoort and Louis Trichardt during 1986-1999(Mpheya et al., 2004).
IONS AMERSFOOT LOUIS TRICHARDT
b b Volume Weighted Wet Deposition Volume Weighted Wet Deposition
Mean(µeq/L) (mmol/m2.yr) Mean(µeq/L) (mmol/m2.yr)
pH 4.35 329.0 4.91 H+ 44.9 68.2 12.2 73.1 Na+ 9.3 163.4 9.3 56.1 + NH4 22.3 34.1 9.7 58.0 K+ 4.7 68.6 3.8 22.8 Ca2+ 18.7 24.5 12.0 36.0 Mg2+ 6.7 183.0 4.1 12.2 - NO3 25.0 71.6 8.0 48.2 Cl- 9.8 216.0 10.0 60.1 2- SO4 59.1 55.3 14.5 43.6 HCOO- 7.5 (6.0)a 44.8 12.9 (11.5)a 77.6
- a a CH3COO 6.1 (2.0) 329.0 8.2 (4.3) 49.3
No of Events 437.0 223.0
Total (mm) 7321.3 6012.2
Annual 563.2 462.5 Mean
The average acidity at Amersfoort (44.9 μeq.ℓ−1) is high compared to that at Louis Trichardt (12.2 μeq.ℓ−1; Table 6.6). A pH below 5.6 was recorded for 98% of samples at Amersfoort and 94% of samples at Louis Trichardt (average pH of 4.4 and 4.9, respectively). Most of the acidity is neutralised by the base cations, 2+ 2+ + Mg , Ca and NH4 (Mpheya et al., 2004).
It was estimated from the average chemical composition, that acidity originates from a mixture of inorganic and organic acids. At Amersfoort, 90% of the acidity originates from inorganic sources, of which 60% is in the form of sulphuric acids, while at Louis Trichardt 50% is derived from organic acids, with nitric and sulphuric acids contributing equal amounts (Table 6.7).
6.31 Non-Point Source Pollution Assessment
Table 6.7: Origin of acidity at Amersfoort and Louis Trichardt (Mpheya et al., 2004)
AMERSFOORT LOUIS TRICHARDT ACIDITY MEQ/L % MEQ/L %
Sulphuric acid 49.2 60 7.8 25
Nitric acid 25.0 30 8.0 25
Organic acids 8.0 10 15.8 50
Total H+, estimated 82.2 31.6
H+ measured 44.9 12.2
Both Amersfoort and Louis Trichardt sites do not have a high population density, or numerous vehicles.
However, Amersfoort is downwind of the industrial region where NOx emissions are high. At both sites, 3- + 2− NO , NH4 and SO4 all of which can be attributed to anthropogenic pollution, are highly correlated to each other.
Rainwater is controlled by five sources: (1) marine, (2) terrigenous, (3) nitrogenous, (4) biomass burning and (5) anthropogenic sources. Table 6.8 shows the estimates of the relative contribution from the different sources to the chemical composition of precipitation at Louis Trichardt and Amersfoort. These estimates suggest that the fossil fuel sources were the highest contributor to the total precipitation content at Amersfoort. At Louis Trichardt, marine, terrigenous and biomass sources contribute more or less equal amounts to the total precipitation content (Mpheya et al., 2004)
Table 6.8: Relative contribution from different sources to the chemical composition of precipitation at Louis Trichardt and Amersfoort (Mpheya et al., 2004).
SOURCE AMERSFOORT(%) LOUIS TRICHARDT(%)
Marine 11 23
Terrigenous 19 27
Fossil Fuel 35 15
Biomass 9 24
+ + Other(H and NH4 ) 26 11
Chemical data for precipitation at Amersfoort and Louis Trichardt were analysed in greater detail for + possible seasonal patterns. The highest concentration of NH4 was recorded at Amersfoort in 1998/1999. + + The NH4 ion is biologically converted to nitric acid after deposition, which ultimately makes NH4 an 2− + 3- + acidifying substance (Mpheya et al., 2004). SO4 , H , NO and NH4 show a strong seasonal variability
6.32 Non-Point Source Pollution Assessment at Louis Trichardt. At Amersfoort ions did not exhibit a seasonal pattern due to the dominance of relatively constant industrial emissions.
Visibility In 1994, Eskom undertook a study investigating a quantitative analysis of visibility in the Mpumalanga Highveld (Turner, 1994). Results from this analysis showed that the mean visibility range of 76 km, with a seasonal high of about 105 km and a low of 60 km. Whilst the range was over 100 km on 10% of the days measured, it was as low as 40 km on almost half the days and as low as 30 km on over 20% of the days (Turner, 1994). The common view is that air quality is degraded in parts of the Mpumalanga province and that a visibility problem exists. However, it is extremely difficult to quantify the contributing factors. Visibility can be impaired by naturally occurring phenomena such as high levels of water vapour and natural dust as well as human induced phenomena (including emissions from industrial activity, household fuels, motor vehicles, vegetation fires, mining, agriculture and waste production). To a greater or lesser extent all of these sources are present in Mpumalanga. The study conducted concludes that emissions of particulates and gases by power stations “do not play a major role in regional visibility impairment” (Turner, 1994). Eskom attributes poor visibility mainly to smoke from biomass burning, smouldering coal dumps and surface dust.
6.6.3 Ash Disposal
The Power Generating Industry produces large tonnages (25 million tons) of solid waste (combustion fly ashes) each year, most of which is consigned to land disposal (ash dams or ash dumps). Depending on coal quality, large coal fired power stations can produce as much as 70 Mt of ash per day. Approximately 1.2 million tons of ash per year is sold to amongst others, the cement industry where the ash is used as a cement extender. A summary of the inputs and outputs of ash disposal is shown in Figure 6.25.
Fly Ash Dust (Air Bottom Ash WET/ DRY Pollution TSP) ASH Rain water DISPOSAL Leachate Effluent: conditioning and dust suppression (brine, blowdowns) Surface Ash Water Return Runoff (WET ASHING)
Effluent Discharge
EFFLUENT (ZLED POLICY) Rain water TREATMENT
Figure 6.25: Ash Disposal
Coal combustion products, referred to as ash, are the resultant solid residues generated by coal-burning utilities in the production of electricity. The inorganic impurities, known as coal ash, either remain in the combustion chamber or are carried away by the flue gas stream. Larger particles of ash, coarse ash (also referred to as bottom ash or boiler slag) settle at the bottom of the combustion chamber, and the fine portion (fly ash) remains suspended in the flue gas stream. The fly ash to coarse ash ratio is a function of
6.33 Non-Point Source Pollution Assessment the type mill used to pulverise the coal. Boilers equipped with tube mills generally produce approximately 10% coarse ash (90% fly ash) whereas boilers equipped with ball mills generally produces 20% coarse ash (80% fly ash).
The fly ash is removed from the flue gas stream (exhaust gases from the boiler) by means of electrostatic precipitators or bag filter systems. Coarse ash drops down from the furnace and collects at the bottom in the ash hopper of the boiler (Eskom Generation Communication GFS 0011, 2003). After being removed from the collecting hoppers, the fly ash and coarse ash is stacked on huge ash dumps or ash dams (slurry dams) where ash settles out and the water is recycled (Figure 6.26, Eskom Generation Communication GFS 0011, 2003).
Eskom implements a Zero Liquid Effluent Discharge (ZLED) water policy, which means that the quality of the water it returns to rivers and dams must be at least as good as the water it draws from these sources.
Figure 6.26: Aqueous input and output streams: coal fired power generation
Two waste management systems are encountered at coal fired power plants, i.e.
Wet ash disposal
Ash is dumped on wet ash dams in shallow paddocks formed through the construction of day walls on top of the ash dam / dump. Ash is slurried with effluent water and hydraulically transported to the ash dam where the ash particles settle and the effluent is pumped back to the power station for reuse. The water is continuously re-used and is referred to as ash water. Losses as a result of evaporation
6.34 Non-Point Source Pollution Assessment
and absorption (interstitial hold) are replenished by the controlled disposal of effluents. Wet ashing systems are designed to cope with 1 in 100 year rainfall events
Dry ash disposal.
Dry ash disposal is on ash dumps. The ash is transported to these dumps via a conveyer belt. In order to prevent dust blow off and blockage of transfer chutes the ash is moistened with waste water to approximately 15% (wet basis) moisture content.
There are three methods of handling ash (1) Above-ground ash dumping: Ash is conveyed to an ash dump, within the power station precinct, where it would be stacked and spread. The dump would be continuously rehabilitated with topsoil and re-vegetated as it develops; (2) Back ashing: This refers to dumping ash within the open-cast coal mine, after all the usable coal has been excavated. The ash would then be stacked, spread, rehabilitated with topsoil and re-vegetated; and (3) In-pit ashing: The difference between this method and back ashing is that the ash would be placed directly into the existing excavation and the overburden and topsoil would be placed on top of the ash. Thereafter the dump would be re-vegetated.
Table 6.9 depicts effluent resulting from the two waste management systems encountered.
Table 6.9: Effluent resulting from dry ashing and wet ashing disposal systems (Hansen et al., 2002)
DRY ASHING SYSTEM WET ASHING SYSTEM
% moisture retained in ash 15% % moisture retained in ash 35%
Dust suppression effluent Slurrying effluent
Ash conditioning effluent % water to ash water return dam
6.6.3.1 Composition of Coal Combustion Products
The characteristics of fly ash differ depending on the composition of the parent coal, combustion conditions and type of emissions control.
In general, the fly ash produced from South African coal is a highly alkaline aluminosilicate fly ash composed primarily of aluminosilicate glass, mullite and quartz. Fly ash is a fine, silt-sized material with a specific gravity of 2.2. With destruction of the organic matter in coal, the concentrations of trace elements in fly ash are higher than the equivalent concentrations in the source coal. Enrichment associated with combustion may concentrate elements by factors of 4-10 times (Jankowski et al., 2006). The trace metal composition of raw coal, coarse ash and fly ash generated at a power station in Mpumalanga is shown in Table 6.10. The chemical composition of fly ash collected from electrostatic precipitators at a power plant in the Mpumalanga Region as reported by Surender and Petrik is shown in Table 6.11.
6.35 Non-Point Source Pollution Assessment
Table 6.10: Trace metal composition of raw coal, fly ash and coarse ash (Scorgie and Thomas, 2006)
RAW COAL COARSE ASH FLY ASH TRACE ELEMENT (MG/KG) (MG/KG) (MG/KG)
Arsenic (As) 2.95 3.64 13.95
Barium (Ba) 505.28 1133.37 962.36
Bismuth (Bi) 1.49 4.00 3.38
Cobalt (Co) 4.82 9.49 7.25
Chromium (Cr) 57.02 356.39 275.94
Copper (Cu) 16.76 23.26 25.72
Gallium (Ga) 16.89 18.64 24.31
Germanium (Ge) 1.98 3.18 4.34
Lead (Pb) 20.38 44.39 52.61
Mercury (Hg) 0.44 0.02 0.13
Nickel (Ni) 25.69 77.95 77.95
Niobium (Nb) 17.61 14.85 13.02
Rhiobium (Rb) 14.67 30.52 33.73
Selenium (Se) 498.27 1121.11 1154.84
Thorium (Th) 3.90 39.74 49.89
Tin (Sn) 3.59 6.36 10.64
Tungsten (W) 2.55 9.06 11.88
Uranium (U) 2.97 10.25 10.96
Vanadium (V) 41.71 80.09 78.54
Yiddium (Y) 24.36 44.18 45.32
Zinc (Zn) 18.64 110.23 26.06
Zirconium (Zr) 143.67 184.26 179.80
6.36 Non-Point Source Pollution Assessment
Table 6.11: Chemical composition of fly ash produced at a power station in Mpumalanga (Surender and Petrik)
FLY ASH COLLECTED FROM ELECTROSTATIC PRECIPITATOR
(XRF ANALYSIS) MAJOR SAMPLE 1(%) SAMPLE 2(%) SAMPLE 3(%) ELEMENTS
SiO2 53.390
TiO2 1.342 50.9 Al2O3 23.402 47.2-54.4 1.40 Fe2O3 4.721 1.5-1.8 25.60 MnO 0.059 23.4-24.9 5.20 MgO 2.698 3.1-4.8 0.05 CaO 8.434 0.02-0.05 2.70 Na2O 0.351 1.5-2.2 6.90 K2O 0.493 10.4-11.6 0.01 P2O5 0.348 0.1-0.4 0.40 SO3 0.033 0.5-0.8 0.33 Cr2O3 0.011 0.06 NiO 0.0189
V2O5 0.0516 TRACE MG/KG ELEMENTS Cu 47.34 Mo 5.229 Ni 93.41 Pb 56.35 Sr 1463.9 Zn 57.33 Zr 488.1 Co 18.25 Cr 179.2 V 147.4 Ba 928.0
6.6.3.2 Non-Point Source Pollution associated with Ash Disposal
The major potential hazard associated with the combustion residues (solid and slurry) in disposal of coal ash is the leaching of potentially toxic substances such as heavy metals and salts into the terrestrial ecosystem if they remain mobile and bio-available. These substances may accumulate and become a concern in the environment. The term “leachate” refers to liquids that migrate from ash dumps/dams
6.37 Non-Point Source Pollution Assessment carrying dissolved contaminants. Leachate results from precipitation entering the ash dam/dump or from moisture that exists in the ash when it is disposed.
Fly ash is a very heterogeneous material. A number of metals and metalloids is present as carbonates, oxides, hydroxides and sulphates. Different elements in various concentrations and forms can be adsorbed or directly attached to solid particles.
In general, the major environmental impacts are usually associated with changes in water chemistry through interactions between the ash and an aqueous solution. The hydrodynamic behaviour in ash deposits is complex and is further complicated through pozzolanic or cementation reactions (Hodgson and Krantz, 1998).
Fly ash has very low permeability, which means that there is very little passage of water. When a residue is wetted with environmental fluids such as rain, groundwater or acid mine drainage, the fluid infiltrate the residue and various components may start to dissolve. The principal processes affecting the leaching process are dissolution of primary solids, precipitation of secondary solids as well as redox, sorption and hydrolysis reactions (Jankowski et al., 2006). Due to very low flow, the mobilisation of trace elements from fly ashes is a very slow process. Non-toxic soluble elements will dissolve first in water, but long term leaching of toxic trace elements is associated with slow mobility. Interaction of groundwater and surface water in fly ash emplacements will thus take a long time to remove mobile trace elements from the solid phase. Depending on the hydrogeochemical environment in which the ash is emplaced, this may result in elevated concentrations over long periods of time, creating potential contamination of associated groundwater and surface water systems (Jankowski et al., 2006).
The release of trace elements from fly ash is related to the leachant solution, but is not a simple function of pH. Numerous studies (for example results presented in Figure 6.27) have been aimed at identifying likely precipitation/dissolution reactions and solid species formed, including the likely solubility.
Data from various studies strongly indicate that the release of each trace element is controlled by a unique set of chemical, thermodynamic and kinetic factors. It is also apparent that these trace element factors are not the same in all fly ash samples. Factors that may contribute to the solubility of a particular element are the pH, ionic activity of the solution, and the mineralogy of various compounds in the fly ash.
6.38 Non-Point Source Pollution Assessment
50
45
40
35
30
25 kg/t
20
15
10
5 pH 3 0 Kendal (pH 8) pH 3
n Duvha (pH 8) iniumoro e B lciumpper pH Ca Co Zinc n Alum ium Ti d m c Arnot(pH 8) Magnesium denum ManganesChromium ylliu eni Vana yb Mercury s er Iron B Ar rontiumNickel Mol um St Cobalt i ar B Cadmium
Figure 6.27: Release of trace elements from South African fly ash when exposed to leachants with pH values 3 and 8. (Hodgson and Krantz, 1998) Stuart et al. (1997) investigated the effects of Ash Dam Leachates on groundwater at a Thermal Power Station in Mpumalanga. The characteristics of ash waters from the power station are shown in Table 6.12.
Table 6.12: Characteristics of ash waters at a thermal power station in Mpumalanga
pH HIGH (>11),
Conductivity > 700 mS/m
Alkalinity >1300 mg/l CaCO3
Calcium >900 mg/l
Sulphate >800 mg/l
Fluoride 1.2 mg/l
Boron 1.14 mg/l
hexavalent chromium 0.2 mg/l
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The high pH of the ash water is related to the hydration of calcium oxide present on the ash particle surfaces (Stuart et al., 1997):
CaO + H2O – Ca(OH)2
The increased pH in the ash water, which contains alkalinity and hardness, results from the following (Stuart et al. (1997)):
+2 - Ca(HCO3)2 → Ca + 2HCO3 - 2- + HCO3 → CO3 + H 2- - - CO3 + H2O → HCO3 + OH The water thus percolating through the ash dam (leachate) can be regarded as an alkaline solution of calcium sulphate, lime and calcite. The leachate plume which infiltrates into the subsurface will be characterised by a high pH (>11) and elevated sulphate and calcium concentrations (Stuart et al., 1997).
Results from groundwater monitoring boreholes sampled quarterly for a period of seven years indicated that calcium and sulphate concentrations are highly variable in the groundwater in ash disposal areas and that calcium concentrations (typically 20-60 mg/l) are consistently higher than sulphate concentrations (typically 10-30 mg/l). The pH levels are near neutral (7-8) and alkalinity typically varies from 50 mg/l to
200 mg/l CaCO3. These monitoring results indicated that seepage from the ash dam is occurring but is not excessive (Stuart et al., 1997).
6.6.4 Overall Impact on Water Sources
The Mpumalanga provincial boundary runs through four of South Africa’s Water Management Areas (WMA) as shown in Figure 6.26. Nearly half of Mpumalanga (53%) is drained by the Olifants River System, the Orange River System (Vaal River), Inkomati River System (Crocodile, Sabie, Sand and Komati Rivers) and the Pongola River System (Usutu River) (DACE, 1999). The Olifants River from the steenkoolspruit continues to the inflow into the Witbank Dam. It is often extremely difficult to assign specific proportions of environmental impact to different industrial sectors where these occur on close proximity to one another.
Water quality in Mpumalanga is impacted on by: Mining,
Electricity generation,
Manufacturing,
Agriculture (fertilizers and pesticides)
Municipal Sewage systems and
Forestry.
Other activities which impact on water resources in the Little Olifants-Riet sub-catchment include:
Landfills and solid waste disposal sites at all towns;
Disposal of liquid (domestic, light and heavy industrial) effluent at all towns;
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Moderate volumes of runoff from towns, as well as all other urbanized areas;
Non-Point domestic effluent from numerous small settlements and farms;
Minor Non-Point impact from non-intensive commercial or subsistence agriculture;
Non-Point impact of agricultural return flows from intensive irrigation areas; and
Litter and domestic garbage discarded alongside the many roads and highways that traverse the sub- catchment.
Eight Eskom power stations are located within the larger Olifants Catchment in the Mpumalanga province. Their localities are shown in Figure 6.28.
Figure 6.28: Water Management Areas in Mpumalanga
All towns (7 towns), mines (37 coal, 6 brick, 17 sand, 4 felsite and 7 clay mines), power stations (8 coal fired power stations) and industries in the Little Olifants-Riet sub-catchment rely on water supplied from water supply reservoirs. Additional water is brought into the sub-catchment via inter-basin transfer schemes from the Komati, Usutu and Vaal systems, principally to meet the large volumes requirements of the eight power stations located in this sub-catchment. The Komati-, Hendrina-, Arnot- and Duhva Power Stations receive water from the Komati system, the Kriel Power Station from the Usutu system and the Matla Power Station receive water from the Vaal System and a small portion of its make-up water (<2%)
6.41 Non-Point Source Pollution Assessment from the Usutu System. Irrigation is a major water use sector in the upper catchment and at the time of the study, 4760 ha of land was irrigated.
The South African Department of Water Affairs and Forestry (DWAF) is responsible for the management of all aspects of water supply and water use in the sub-catchment. Each coalmine and thermal power station also collaborates in the management of their water supplies and in the disposal of their wastes and effluents. In addition, DWAF also regulate the quantity and quality of all effluent discharges through a system of effluent discharge permits or licences. Each licensed effluent discharger is required to carry out a routine monitoring programme of the flow and quality of their effluent and supply this to DWAF. The Department then conducts a randomised series of audit samples to check the veracity of the effluent returns submitted by each discharger.
Several studies have been conducted to investigate the influence of atmospheric deposition and leaching on water and soil quality in the Mpumalanga Region. Salinity and acidity are the major water quality problems associated with atmospheric pollution. Water is furthermore an excellent solvent and transport medium for particulates.
Salinisation refers to the process whereby the concentration of dissolved salts (salinity) increases (Williams, 1987). Salinisation is depicted by total dissolved salts (TDS) levels (DWAF, 1996). The TDS concentration is related to the Electrical Conductivity (EC) of the water.
During a monitoring program that was initiated in 1996 with the objective of detecting changes in soil chemistry that may be related to acidic deposition, soil samples were collected in a number of profiles at depth intervals of 10 cm along a 20 km transect downwind of a coal-fired power station in Mpumalanga (Abanda et al., 2001). The soils were characterized both physically and chemically in the field and laboratory. Soils in the region are deep, highly buffered, well drained and generally acidic. The average base saturation is 78%, pH (KCl) ranges between 4.5 and 5.0, clay content ranges between 5 and 20% and the organic carbon content ranges between 0.4 and 2.0% (Abanda et al., 2001). Saturated paste 2- 2+ extracts of the soils showed that SO4 and Ca are the dominant anion and cation species, respectively. The determination of pH, exchangeable acidity and S content of the soils confirmed earlier results indicating that there is no significant gradient in these parameters with distance from the power station and failed to provide any indication of a trend towards increasing acidification and sulphur enrichment with time(Abanda et al., 2001). Leaching of sulfate, the buffer capacity of the soils and the possible co- deposition of fly ash emissions are suggested as possible explanations for the absence of detectable changes in soil chemical properties with either distance or time.
Skoroszweski, (2000) did a study on the Suikerbosrand catchment, a small undisturbed catchment in the Vaal catchment, to determine the relationship between atmospheric deposition and water quality. The study indicated that sulphate was the most common chemical variable in terms of salinity. Sulphate contributed 30% to 44% of the total salt load in the catchment. Bosman (1990) found similar results. A study conducted in the Vaal Dam catchment indicated that increased runoff causes atmospherically deposited sulphate to be washed out of the soil and released into surface waters (Bosman, 1990). It was found that during dry periods atmospherically deposited sulphate is retained in the soil (Bosman, 1990). A four-year study indicated that only 36% of the atmospherically deposited sulphate was exported during dry years, but that 92% was exported during wet years (Bosman, 1990). As South Africa has more “dry years" than “wet years”, this would suggest a considerable accumulation of sulphate soils. Dry years refer to periods of low rainfall and wet years refer to periods of high rainfall.
The 2003 Mpumalanga State of the Environment Report state that surface water nutrients are routinely checked. Water quality indicators have shown a general decrease in water quality over the past 6 years.
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Median levels of surface water nutrients have increased and indicate a potential for enrichment. The consequences of these elevated levels are:
A greater potential for algal blooms;
An impact on riverine ecosystems; and
Impairment of human health.
High (and increasing) Total Dissolved Salt levels in the Olifants and Usutu WMAs have the potential for decreasing the aesthetic value of the water. Consumption of the water (if not treated) may produce adverse health effects over the long-term if ingested by sensitive individuals (DWAF,2002a).
At the WMA scale, high exceedances from water quality guidelines exist for pH levels in the province. These deviations can result from conditions being either too acidic or too alkaline. Actual pH levels at particular sites need to be determined before effects of activities such as mining (through acid mine drainage) or power generation can be determined and activities held accountable for such impacts on water quality. High levels of aluminium, iron and manganese also exist in surface waters in the Mpumalanga Province (DACE, 2003). Barta, 2005 reported that the main water quality problem in the Vaal River System is salinity which has been rising in recent years (Herold and Rademeyer, 2000). The increase in total dissolved salts concentrations are caused by
Deposition of atmospheric pollutants
Unabated pollution from underground mining operations
Irrigation and
Urban Run-off.
Evidence of increases in groundwater nutrient concentrations can be seen in 6 other regions in Mpumalanga. The 2001 concentrations are still within acceptable levels for domestic purposes (i.e. below 10 mg/l) and do not pose a threat to human health if ingested. These groundwater regions are the Eastern Bushveld, Eastern Bankenveld, Lowveld, NorthEast Middelveld, Central Highveld and Eastern Highveld groundwater regions (DACE,2003). Barta (2005) estimates that almost half of the total salt load originates from Non-Point pollution sources.
6.7 Nuclear power generation
There is only one nuclear power generating plant in South Africa, which is situated in the Western Cape. Nuclear reactors utilise energy released when heavy elements such as Uranium (U235) or Thorium (Th232) are subjected to nuclear fission (splitting if atoms). This process takes place in the nuclear reactor core and occurs when the U-235 / Th-232 nuclei are bombarded with thermal (slow) neutrons. The fission process generates heat energy, which is carried away by means of a circulating coolant (purified water, which is kept at a high pressure) and is used to raise steam through tubes in the steam generator which drives the turbines to produce electricity. Once the steam has driven the turbines, it flows to condensers where another water system is used to cool and condense steam back to water, which is circulated back to the steam generator. Figure 6.29 shows a schematic diagram of the nuclear power generating process.
6.43 Non-Point Source Pollution Assessment
To grid
Transformer Steam Generator Exciter
Steam Nuclear Turbine Reactor Valve Alternator Coolant pump
Feed water pump
Condenser
Circulating water pump Cooling Tower
River
Figure 6.29: Schematic diagram of the nuclear power generating process.
6.7.1 Nuclear power generation waste disposal
As a result of operating a nuclear power station or facility, a wide variety of radio-isotopes will be produced. These are basically unstable nuclei which emit hazardous radiations. The most penetrating of these is the gamme (γ) radiation, which is a short wavelength electromagnetic emission. Because it is so penetrating, gamma radiation can give rise to significant exposure hazards even at appreciable distances from the source (Probert and Tarrant, 1989). The other types, β and α radiation are particulate in character and these particles will do most damage to humans and animals if they are inhaled or ingested.
Some important isotopes and their half-life are shown in table 6.13 below. The half-life indicates to some extent how long a particular isotope will remain a hazard in the environment.
Table 6.13: Important Isotopes resulting from nuclear power production
RADIO-ISOTOPE TYPE OF EMISSION HALF-LIFE
Hydrogen-3 β 12 y
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RADIO-ISOTOPE TYPE OF EMISSION HALF-LIFE
Carbon-14 β 5600 y
Argon-41 β,γ 1.8 h
Potassium-40 β,γ 1.3 x 109 y
Krypton-85 β,γ 11 y
Strontium-90 β 28 y
Yttrium-91 β 64 h
Ruthenium-106 β,γ 1 y
Iodine-131 β,γ 8 d
Xenon-133 β,γ 5.3 d
Caesium-137 β,γ 30 y
Uranium-235 α 7.1 x 108 y
Plutonium-239 α 24360 y
At nuclear power stations the initial build-up of radioactivity occurs in the fuel rods in the core of the reactor and most of the radioactivity will remain in the rods until they are removed and sent for further processing.
There are three types of nuclear waste: low, intermediate and high level.
Low-Level waste (LLW) consists of day-to-day refuse such as paper, gloves, glassware, plastic containers, disposable overalls and overshoes, most of which have low traces of radioactive contamination. LLW is compressed into steel drums, sealed and transported for disposal.
Intermediate-level waste (ILW) consists of radioactive resins and sludges, spent filter cartridges and scrap metal pieces from normal maintenance work. ILW is solidified by combining it with a sand/cement mix which is poured into concrete drums. The drums have a design life of hundreds of years, although the waste they contain will reach natural radiation levels after 50 years.
High-level waste is the residue left over when the spent fuel has been chemically processed to remove usable plutonium and uranium. Initially, the spent fuel assemblies are stored under water, which cools the fuel rods and serves as an effective shield to protect workers in the fuel storage building from radiation.
Radiation starts decreasing immediately and within about ten years has decreased by more than 95%. On removal from the pool, the spent fuel is placed in dry storage flasks which are about six metres high by two-and-a-half metres wide and weigh approximately 120 tons. After transport to the storage site the flasks are kept in suitably designed buildings on the surface. They will be removed only when uranium recovery becomes economically viable. Then the spent fuel may be sent to a reprocessing plant.
Nuclear waste storage sites are situated in remote, geologically stable areas where little seismic activity has been recorded for millions of years. South Africa’s site for the disposal of nuclear waste, belonging to
6.45 Non-Point Source Pollution Assessment the NECSA, is situated at Vaalputs – 600 km north of Cape Town – where the annual evaporation exceeds the annual rainfall. In this way, even if radioactivity should escape, it theoretically could not contaminate ground water which may find its way to the surface. The area allocated for burial of metal drums and concrete containers measures 700 m x 300 m. This area is sufficient for storing the nuclear waste of three power stations the size of Koeberg for 40 years. The waste is stored in trenches 10 m deep. Radiation at the surface is at almost natural levels and constitutes no health hazard. However, for safety reasons, the area is fenced off and monitored.
Koeberg produces some 500 drums of LLW per year and 300 drums of ILW per year. By comparison, a similarly sized coal-fired station produces about 1,5 million tons of ash each year. Effluent by nuclear plants which are discharged to the sea include:
sewage Effluent
treated Radiological Effluent
conventional Liquid Effluent and
cooling water.
6.7.2 Non-Point Source Pollution associated with Nuclear Power Generation
The treated radiological effluent that is released to the environment constitutes the main pathway and associated risks. The main pathway of interest is the marine.
The marine pathways (Figure 6.30) arise from treated radiological effluent that is discharged into the sea. Typically, the waste will contain very low levels of radioactivity. Some isotopes can remain mobile for long periods in seawater and eventually enter the food chain after being adsorbed or ingested by marine flora and fish (Probert and Tarrant, 1989). Radio-nuclides become concentrated in edible parts of sea-foods.
MARINE DISCHARGE FROM NUCLEAR FACILITY
SILT SEAWATER
DISPERSION RESUSPENSION DEPOSITION DISPERSION RESUSPENSION Air External Irradiation Air
Figure 6.30: Environmental pathways associated with discharge of treated Radiological Effluent into the sea
6.8 Hydro electric power generation
Conventional hydro-electric schemes operate on the principle of converting the potential energy of water stored in a dam into electrical energy. Figure 6.31 shows a schematic diagram of the hydro-electric generating process.
6.46 Non-Point Source Pollution Assessment
Figure 6.31: Schematic diagram of the hydro-electric power generating process.
Water is conveyed through pressure tunnels to a hydraulic turbine driving a generator coupled to it. Energy generated is fed into the transmission lines linked up to the national grid. The water exiting the turbines is discharged below the power station to run back into the river and continues its course. Hydro- electric schemes use the water only once.
In pumped storage schemes energy is used to pump water into an elevated dam from which it is released to generate energy when it is needed. A pumped storage scheme consists of a lower and an upper reservoir with a power station between the two. Energy is used during periods of low demand to pump water from the lower to the upper reservoir. This water is then allowed to run back into the lower reservoir through the turbines to generate electricity at peak demand periods.
Pumped storage schemes and hydro-electric power generation plants serve as emergency- or peaking power stations. The country’s potential for hydropower is limited due to seasonal flow of the country’s rivers and frequent droughts.
6.8.1 Non-Point Source Pollution associated with Hydro-Electric Power Generation
The most important Non-Point source of pollution related to hydroelectric power generation is bacterial decomposition of organic matter in hydroelectric reservoirs which produce greenhouse gases.
Bacterial decomposition (both aerobic and anaerobic) of organic matter in water reservoirs produces mainly carbon dioxide (CO2) and methane(CH4.) Each additional kilogram of CH4 introduced to the atmosphere blocks more of the earth’s transmitted heat than one kg of CO2 (Rosa and dos Santos, 2000).
This is because the absorption of infrared radiation by CH4 is higher than by CO2.
The pattern of gas emissions from a Carbon Dioxie reservoir differs completely from the pattern of emissions from a fossil-fuel power plant. CO2 emissions from the combustion of coal for power generation are released uniformly over the entire period of operation of the plant whereas the production of both CO2 and CH4 from the bacterial decomposition of organic matter in a hydroelectric reservoir can be concentrated in time and can decay over a period much shorter than the lifespan of the reservoir. Ion addition there will be long term emissions due to the decomposition of residual stored biomass remaining in the reservoir after an initial intense degradation, as well as from new biomass produced over time inside the reservoir and from organic matter from the watershed (Rosa and dos Santos, 2000). The
6.47 Non-Point Source Pollution Assessment magnitude and pattern of emissions will vary depending on factors such as the soil type, biomass density and physico-chemical parameters of the water.
Rosa and dos Santos (2000) reported the following elements that need to be calculated to compare emissions from hydro and coal power (Table 6.14).
Table 6.14: Elements used to compare emissions from hydro and coal power
HYDRO COAL COMBUSTION
Rated capacity and energy generation
Flooded area of reservoir Rated capacity and energy Biomass density and type generation Soil type and basin drain Technology and energy efficiency Depth of flooding Coal properties Carbon content of biomass Coefficient of carbon emissions Rate of decomposition
Anaerobic decomposition percentage
Due to the size and application of hydroelectric power plants in South Africa it is assumed that emissions are predominantly low intensity emissions and that data are not available to quantify greenhouse gas emissions from hydroelectric power plants.
6.9 Risk Assessment
The emissions and effluents arising from the various processes of power production possess the potential to contaminate the environment and directly influence humans. The environmental risk assessment is based on the potential for pollutants to impact the environment through their distribution in waste products from combustion (Australian Coal Research Ltd. 1996).
The risk matrix has four components Environmental Area
Unit activities
Risk impact and
Risk rating
With this knowledge an attempt was made to quantify risks and identify problem areas.
6.9.1 Environmental Areas
The risk assessment matrix assesses risk in three environmental areas. These areas are
6.48 Non-Point Source Pollution Assessment
air pollution,
water pollution, and
land pollution.
Emissions resulting from coal combustion releases (1) greenhouse gases, (2) acid gases and metals to air as well as water and land through processes of wet and dry deposition. Leaching from coal combustion product disposal result in releases of (1)metals and (2)salts to water as well as land.
6.9.2 Unit Activities
The risk assessment matrix used considers two lifecycle stages. These are Material Processing : Coal Combustion and
Coal Combustion Product Disposal
Various configurations for similar unit operations are applied in the power generating industry. These are listed in the Table 6.15.
Table 6.15: Unit Operations : Coal Fired Power Generation
MATERIAL PROCESSING COAL COAL COMBUSTION PRODUCT COMBUSTION DISPOSAL
Coal Combustion : NO emissions control Effluent
Coal Combustion : Particulate Matter Control Dry Ashing System (Electrostatic Precipitators / Bagfilters)
Coal Combustion : Particulate Matter control Wet Ashing System (ESP / BF) & Desulphurization
Emission Control systems have a significant effect on the pollutants entering the atmosphere and water/land. Average trace element removal efficiency for different emission control devices is shown in Table 6.16.
Table 6.16: Average Trace Element Removal Efficiency (%) for control devices
FGD COMPOUND ESP ESP/SCRUBBER SCRUBBER
Arsenic 87.5 96.9
Beryllium 91.9 94.3
Cadmium 74.6 94.4
Chromium 71.5 91.8 92.9
6.49 Non-Point Source Pollution Assessment
FGD COMPOUND ESP ESP/SCRUBBER SCRUBBER
Manganese 78.1 89.1 97.7
Nickel 79.1 96.4 97.2
6.9.3 Toxicity and Pollution Rating
To evaluate overall risk the stream content of toxic substances and pollutants must be considered. Based on a toxicity and pollution scale, obtained from a model that includes damages produced to biotic and abiotic resources by substances generated from fossil fuel combustion, risks were calculated for substances emitted in combustion gases and leachate.
Montero (2006) developed a model to score and rank pollutants emitted to the environment taking into account the toxicity and pollution of these chemicals. His model is based on a detailed review of the physical and chemical properties of the chemicals as well as parameters used in environmental studies based on the behaviour expected from each of the components in the environment.
The model evaluates produced impacts by substances to biotic and abiotic resources by nine functions (Table 6.17) that allowed calculating a toxicity and pollution factor (TPF) as shown in Table 6.18. All functions take values from 0 to 100.
Table 6.17: Functions used to evaluate Toxicity and Pollution Factor (TPF)
FUNCTION RISK EVALUATED
FCH Cancer in human beings
FTINH Toxicity by inhalation in human beings
FTING Toxicity by ingestion in human beings
FTBF Toxicity by biocancentration in fish
FTAEF Toxicity by acute exposition in fish
FTCEF Toxicity by chronic exposition in fish
FTS Toxicity by adsorption in soil
FGW Global warming impact
FAR Acid Rain impact
6.50 Non-Point Source Pollution Assessment
Table 6.18: Toxicity and Pollution Factors (TPF) for various chemical compounds
Based on the data published by Montero (Table 6.19) and hazard values (also on a scale 0-100) for contaminants obtained from the “Chemical Hazard Evaluation for Management Strategies : A method for ranking and scoring chemicals by potential human health and environmental impacts” published by the EPA, toxicity and pollution ratings on a scale 0 (not hazardous) to 10 (extremely hazardous) was assigned to each contaminant inventoried as part of power production processes.
The above risk parameters were used to weight emissions inventoried as part of a life-cycle assessment.
6.9.4 Risk Rating
The risk rating value estimates the probability of a specific contaminant to be released to the environment taking into account (1) the probability to be released and (2) the amount of contaminant released. The risk impact value is simply a judgment based on literature findings. Using a scale of 0 (no probability of being released to the environment) to 5 (extremely high probability of being released to the environment) specific contaminants and the probability to be released from a specific unit operation are rated taking into account the conditions under which units operate.
The criteria shown in Table 6.19 was used to evaluate the probability of occurrence.
6.51 Non-Point Source Pollution Assessment
Table 6.19: Probability of occurrence
Contaminant has a extremely high probability of being released to the 5 environment
4 Contaminant has a high probability of being released to the environment
3 Contaminant has a probability of being released to the environment
2 Contaminant has a small probability of being released to the environment
Contaminant has a extremely small probability of being released to the 1 environment
0 Contaminant has no probability of being released to the environment
The risk impact value (0-5) was multiplied with a value ranging from 0 (not present) to 15 (present in extremely large amounts) to determine an overall risk rating for each contaminant present in each source. Control measures impact on the probability of contaminants to enter the environment.
6.9.5 Overall Risk Factor
An overall risk factor for each configuration was determined by multiplying the toxicity and pollution rating for each contaminant with the risk rating assigned to each source configuration and added to give an overall risk factor. The Overall Risk Factor for various coal fired process configurations is shown in Figure 6.32.
9000
8000
7000
6000
5000 <50MW 4000 300-1000MW RISK RATING >2000MW 3000
2000
1000
0 No Emission No Emission ESP & Wet ESP & Dry ESP, FGD & ESP, FGD & Control & Wet control & Dry Ashing Ashing Wet Ashing Dry Ashing Ashing Ashing
Figure 6.32: Overall Risk Factors for various coal fired process configurations
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6.10 Summary
The power generation industries, especially the coal-based power plants, implement procedures to improve its environmental performance.
Available evidence suggests that the primary causes of environmental impacts are:
Resource depletion. Coal fired power plants are significant consumptive users of water, and
Resource (air, water and land) pollution resulting from
- Pollutants emitted to the atmosphere - Atmospheric wet and dry deposition - Acid rain - Leaching of potentially toxic substance into the eco system - Spillages Quantitative data collected indicate/suggest that:
The Mpumalanga Province accounts for 91% of SA’s NOx emissions (Held and Mphepya, 2000),
More than 60% of the NOx emissions in the Highveld occur from stacks taller than 200 m and originate mostly from 8 large coal fired power plants and a synthetic fuel processing complex (Held et al., 1999),
The total annual deposition rate of nitrogen at Amersfoort (representing the industrial area in Mpumalanga including 8 coal fired power stations) is 15 kg N/ha.yr compared to 9 kg N/ha.yr at background sites,
Wet deposition accounts for 63% and dry deposition accounts for 37% of the total deposition of nitrogen at the Amersfoort site,
The total annual deposition rate of sulphur dioxide at Amersfoort (representing the industrial area in Mpumalanga including 8 coal fired power stations) is 23 kg S/ha.yr compared to 3.28 kg S/ha.yr at background sites,
A large proportion of precipitation at Amersfoort is acidic with an average pH of 4.35,
2- Precipitation at Amersfoort is dominated by the SO4 ion,
90% of precipitation acidity at Amersfoort originates from inorganic sources, of which 60% is in the form of sulphuric acids,
Fossil fuel sources might be the highest contributor to precipitation acidity at Amersfoort,
Fly ash has very low permeability, which means that there is little passage of water,
Mobilisation of trace elements in ash dumps/dams is a very slow process,
Elevated concentrations of trace elements may create contamination over long periods of time depending on the hydrogeochemical environment in which ash is placed,
Due to the size and application of hydroelectric power plants in South Africa, emissions are predominantly low intensity emissions and
6.53 Non-Point Source Pollution Assessment
Emissions from release of very low level radiological waste into the sea at the Koeberg nuclear power plant are predominantly of insignificant low intensity.
Studies focusing on water and soil quality in Mpumalanga indicate that:
Salinity and acidity are the major water quality problems,
Sulphate is the most common variable in terms of salinity,
Atmospherically deposited sulphate is retained in the soil during dry periods and wash out of soil during wet periods.
High levels of aluminium, iron and manganese exist in surface waters in the Mpumalanga Province.
Almost half of the salt load originates from Non-Point sources.
6.11 Conclusions and directions for future work
Based on the information collected through personal interviews, assessment of available information and stakeholder participation, the following has been concluded :
It is extremely difficult to assign specific proportions of environmental impact to different industrial sectors where these occur on close proximity to one another.
Synergy doesn’t exist with regards to available information since investigations they are based upon, were done at different times, under different circumstances, to different levels of detail and using different approaches.
Available knowledge of the quantitative atmospheric release and fate of mercury is limited and requires further research investment.
Information on the partitioning of trace elements between the various solid residues in the flue gas (fly ash) and whether any is emitted in the vapour phase is not available for South African power generating processes/plants.
Data for the release of trace elements from fly ash report mainly on laboratory experiments. Information within public domain on samples from actual monitoring boreholes presenting different hydrogeochemical environments is limited.
Information on dust from coal stockpiles and the associated impact on the environment is not available.
Although ZLED policies are implemented, little information is available on the quality and quantity of liquid wastes released to the environment to confirm that these policies are adhered to.
The general enforcement of regulations governing emissions and waste disposal is lacking.
Common principles and harmonized approaches for risk methodologies related to power generation processes needs to be established.
The lack of sufficient, accessible and user-friendly information is perhaps one of the most significant obstacles to perform a proper environmental risk assessment. This includes industry not disclosing the
6.54 Non-Point Source Pollution Assessment full details of their emissions and waste disposal (and problems related to these), and Government Departments reporting information in a co-ordinated and integrated manner.
There appears to be agreement amongst the role-players in the power generating industry about the problems and issues identified. However, there are still significant obstacles to overcoming these challenges, most importantly co-ordination between the different role players, additional financial resources and a substantial improvement in the information and data on waste and emission management.
In order to gain a full understanding of the impact of Non-Point Source Pollution associated with the power generating industry in South Africa further research should be conducted as to establish independent references regarding the matter in a South African context.
6.55 Non-Point Source Pollution Assessment
7 GENERAL DISCUSSION AND RECOMMENDATIONS
The same general conclusions can be drawn from the mining, industrial and power generation sectors. These being:
There is a lack or readily available Non-Point source pollution data in South Africa
There is a lack of willingness to share information
The current legislation does not enforce Non-Point source pollution management of water resources
Consequently this first order assessment indicates that there needs to be research into quantifying the real impacts of Non-Point Source Pollution.
The polluters as well as regulators need to be educated as to the potential impacts of this mainly unquantified source of pollution.
7.1 Mining
From the verification discussions held with members of the mining industry, prominent mine water researchers and available literature the following conclusions can be drawn with regards to Non-Point pollution:
The available literature is sketchy
The mining houses are not forthcoming with data which could be as a result of the current legislation not specifically targeting Non-Point pollution as yet
Literature on a catchment scale is limited
Mine specific data if it is available is highly variable
The range of values related to Non-Point pollution and mines varies from mine to mine as well as from type of mine.
Detailed water balances and catchment specific models are required to accurately determine the impacts of Non-Point pollution as a result of mining activities.
Activities are specific for different types of mines and hence the pollution type and severity varies depending on the activity and the type of mine. Mines also produce a variety of potential contaminants, depending on the ore deposit type, mining processes and mineral processing activities at specific sites.
By-products from gold mines, include uranium and acid/pyrite, which are potential sources of groundwater pollution and acid mine drainage. Coal mining’s impact on the water resources varies according to the life cycle of the mine and coal mines may produce large quantities of acid or saline mine drainage.
Due to the lack of detailed information on the Non-Point sources of pollution from the South African mining industry, the following factors could not been incorporated into this risk assessment:
the differentiation between the impact of the different receptors (e.g. waste rock dumps) between the different mining commodities.
7.1 Non-Point Source Pollution Assessment
the age of the receptors. Age plays a major role on the impact as older mining activities did not include good housekeeping and pollution control measures were not put in place. The chemical characterisation of waste receptors also changes over time
The role of gas emissions from the different mining commodities.
The magnitude of the threat from mining activities is dependent on whether precautionary measures are taken to prevent contamination, but in many cases, the scale of mining operations is such that Non-Point sources of pollution cannot be completely avoided.
Coal and gold mines, especially closed and abandoned mining operations, appear to be the most significant threats in terms of potential groundwater contamination from the mining sector in South Africa. Acid generation and decreasing groundwater pH has been noted in some gold and coal mining areas in South Africa, but in many cases, AMD is neutralised by reaction with the country rock to produce saline drainage instead.
Contamination of groundwater sources from contaminated surface water is possible where there is a direct connection between the resources. The connection to these surface water bodies, contributing to this type of groundwater contamination, can either be natural or man-made.
The range (13 to 51%) of potential Non-Point Source Pollution contributions to salts balances at a catchment scale varied considerably from study to study, commodity mined and season. Despite the uncertainties in the accuracy of these studies the overall contribution of Non-Point Source Pollution originating from the mining industry in South Africa is significant. Detailed catchment modelling would be required to refine the catchment specific contribution of Non-Point Source Pollution originating from the mining industry in South Africa.
7.2 Industries
The collection of Non-Point pollution data from industry has been difficult even though very good cooperation was given by most industry representatives. The overall impression is that the majority of larger industries are well aware of the potential problems associated with Non-Point pollution and that in most cases measures have already been implemented or are being developed to combat this problem. The main ‘hot spots’ in terms of Non-Point sources are the ‘historical’ sites where wastes had been disposed off over long periods of time into inadequately designed facilities and where adequate control was not exercised. These sites are very difficult and extremely costly to rehabilitate and the pollution effects have spread over large areas with contamination of groundwater the most serious problem. The extent of the pollution could not be quantified but from available information the pollution in some historic areas appear to be extensive.
7.3 Power generation
In South Africa, water quality data from individual power stations is not openly available to the general public. Data is considered to be ‘commercial in confidence’ and access is restricted. As a result, the findings of this study could only be achieved and verified based on literature and international results as well as input and verification of results by various role-players
The lack of sufficient, accessible and user-friendly information is perhaps one of the most significant obstacles to perform a proper environmental risk assessment. This includes industry not disclosing the full details of their processes, emissions and disposal (and problems related to these), and Government Departments reporting information in a co-ordinated and integrated manner.
7.2 Non-Point Source Pollution Assessment
There appears to be agreement amongst the role-players in the power generating industry about the problems and issues identified. However, there are still significant obstacles to overcoming these challenges, most importantly co-ordination between the different role players, additional financial resources and a substantial improvement in the information and data on waste and emission management.
Based on the information collected through personal interviews, assessment of available information and stakeholder participation, the following has been concluded :
It is extremely difficult to assign specific proportions of environmental impact to different industrial sectors where these occur on close proximity to one another.
Synergy don’t exist with regards to available information since investigations they are based upon, were done at different times, under different circumstances, to different levels of detail and using different approaches.
Available knowledge of the quantitative atmospheric release and fate of mercury is limited and requires further research investment.
Information on the partitioning of trace elements between the various solid residues in the flue gas (fly ash) and whether any is emitted in the vapour phase is not available for South African power generating processes/plants.
Data for the release of trace elements from fly ash report mainly on laboratory experiments. Information within public domain on samples from actual monitoring boreholes presenting different hydrogeochemical environments is limited.
Information on dust from coal stockpiles and the associated impact on the environment is not available.
Although ZLED policies are implemented, little information is available on the quality and quantity of liquid wastes released to the environment to confirm that these policies are adhered to.
The general enforcement of regulations governing emissions and waste disposal is lacking.
Common principles and harmonized approaches for risk methodologies related to power generation processes needs to be established.
In order to gain a full understanding of the impact of Non-Point Source Pollution associated with the power generating industry in South Africa further research should be conducted as to establish independent references regarding the matter in a South African context.
7.4 Recommendations
The current legislation does not enforce Non-Point Source Pollution management of water resources. The polluters as well as regulators need to be educated as to the potential impacts of these mainly not quantified sources of pollution. General information brochures should be developed as well as educational talks presented to educated and inform about the potential current and long terms impacts of Non-Point source pollution.
7.3 Non-Point Source Pollution Assessment
7.4.1 Mining
It is recommended that the detailed water and salt balances that are set up for mines are revisited to determine and apportion the impacts of Non-Point sources of pollution. Much of this information exists but the mining houses will not readily make this information available.
Catchment models (also using salts) should be set up for say the Upper and Middle Vaal River system to determine the cumulative impacts of the mining industry on the water resources.
Research should be undertaken to determine a set of default values (such as percentage contribution to the salt balance) for Non-Point sources of pollution in the South African mining sector (for both surface and groundwater). This research would need to take into account seasonal variations, mine specific values, source of pollution, etc.
The quantification of the impacts of dust that originates from mine waste dumps needs to be determined. Not only has this impact an effect on human health but it also impacts surface water ecosystems.
7.4.2 Industry
In view of the fact that the main sources of potential Non-Point pollution are industrial complexes, it is recommended
that follow-up projects be developed in cooperation with a selected complex where catchment studies have been done and that the Non-Point pollution be determined from such a study.
that further projects be developed in collaboration with a selected industry to identify the main sources of Non-Point pollution within an industrial complex and that further research be conducted to remediate such sites in the most cost-effective manner.
7.4.3 Power generation
In order to gain a full understanding of the impact of Non-Point Source Pollution associated with the power generating industry in South Africa further research should be conducted as to establish independent references regarding the matter in a South African context.
Common principles and harmonized approaches for risk methodologies related to power generation processes needs to be established.
7.4 Non-Point Source Pollution Assessment
The following Appendices can be found on the enclosed CD:
Appendix A Gold Mining
Appendix B Coal Mining
Appendix C Platinum Group Metals (PGMS)
Appendix D Profile of the Diamond Industry
Appendix E The Iron and Steel Industry
Appendix F Titanium Mining
Appendix G Sand Mining and its Environmental Impacts
Appendix H Manganese Mining
Appendix I Radionuclides in the Mining Industry
Appendix J Organic Contaminants in Mines
Appendix K Base Metals selected in this study
Appendix L Chromium Mining
Appendix M Vanadium Mining