Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 1
IYANGA MINING (PTY) LIMITED (Welgelegen Colliery)
BRIEF APPLICATION REPORT Submitted as contemplated in Section 40 of the National Water Act, 1998 (Act No. 36 of 1998)
March 2020
Report No. 3333/2020
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 2
Report Type: Integrated Water Use License Application: Brief Application Report
Project Title: Welgelegen Colliery: Brief Application Report
Compiled for: Iyanga Mining (Pty) Limited
Compiled by: M.B Magagula, B.Sc. Hons. (Cand.Sci.Nat.)
Reviewed by: O.T. Shakwane, B.Sc. Hons. (Pr.Sci.Nat)
Geovicon Reference: 3333/2020
Version: Draft
Date: March 2020
Distribution List: Pamela Mqulwana
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 3
CONTENTS PAGE
EXECUTIVE SUMMARY ...... 9
1. INTRODUCTION ...... 11 1.1 Who is Developing the IWUL Application ...... 11 1.2 Who will Evaluate the IWULA? ...... 12 1.3 Legal Requirements ...... 12 1.4 Purpose of this IWUL Application ...... 13
2. PROJECT BACKGROUND AND CONTEXT ...... 15 2.1 The Applicant (Iyanga Mining (Pty) Ltd, Welgelegen Colliery) ...... 15 2.2 The Applicant’s Environmental Considerations...... 15 2.3 Overview of the Project ...... 15 2.3.1 Name of the Applicant ...... 15 2.3.2 Name of Mine ...... 15 2.3.3 Name of the Project...... 16 2.3.4 Address of the Applicant ...... 16 2.3.5 Contact Person ...... 16 2.4 Description of the Property ...... 16 2.4.3 Direction and Distance nearest Towns ...... 16 2.4.4 Location...... 16 2.4.5 Name of River Catchments ...... 19 2.4.6 Name and Address of Direct Land Owners ...... 20 2.5 Iyanga Mining (Pty) Ltd: Welgelegen Colliery Method Statement ...... 20 2.5.1 Construction Phase ...... 20 2.5.2 Operational Phase...... 20 2.5.3 Decommissioning/ Closure Phase ...... 20
3. LEGAL ASSESSMENT ...... 23 3.1 National Water Act ...... 23 3.1.1 Applicable sections ...... 23 3.1.2 Summary of Relevant Exemptions ...... 23 3.1.3 Compliance with Section 27 of the National Water Act ...... 23 3.2 Summary of water uses Applied for ...... 27
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 4
BASELINE ENVIRONMENTAL ASSESSMENT ...... 30 3.3 Climate ...... 30 3.3.1 Mean Monthly Rainfall...... 30 3.3.2 Mean Monthly Maximum and Minimum Temperatures ...... 30 3.3.3 Wind Direction and Speed at the Mine ...... 31 3.3.4 Extreme weather conditions ...... 31 3.4 Topography ...... 32 3.5 Soils ...... 32 3.6 Land uses ...... 32 3.7 Surface Water ...... 33 3.7.1 Regional and Local Setting ...... 33 3.7.2 Baseline Hydrology ...... 33 3.7.3 Surface Water Quality ...... 33 3.7.4 Water Quality Analysis ...... 33 3.8 Groundwater...... 35 3.8.1 Regional Geohydrology ...... 35 3.8.2 Aquifer Description ...... 35 3.8.3 Hydrocensus ...... 36 3.8.4 Water Quality ...... 36 3.9 Resource Class and River Health ...... 36 3.10 Sensitive Landscapes ...... 36 3.10.1 Wetland Delineation ...... 37 3.10.2 Wetland Classification ...... 39 3.11 Socio-economic Environment ...... 41 3.11.1 Population Density, Growth and Location ...... 41 3.11.2 Major Economic Activities and source of employment ...... 41 3.11.3 Housing ...... 41 3.11.4 Social Infrastructure...... 42 3.11.5 Water Supply ...... 42 3.11.6 Power Supply ...... 42
ANALYSES AND CHARACTERISATION OF ACTIVITY ...... 44 3.12 Risk Assessment ...... 44 3.12.1 Safety, Health, Environment and Quality Policy ...... 44 3.12.2 Objective and Strategies ...... 44
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 5
3.12.3 Key Performance Area and Indicators ...... 44 3.12.4 Methodology Followed ...... 45 3.12.5 Significance of Possible Impacts ...... 46
MONITORING SYSTEM ...... 51 3.13 Monitoring ...... 51 3.13.1 Surface Water Monitoring ...... 51 3.13.2 Groundwater Monitoring ...... 51 3.14 Environmental Management Performance Assessment and Reporting ...... 52
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 6
TABLES
# Table Page
Table 1: Direction and Distance to Nearest Towns 16
Table 2: Description of immediate and adjacent landowners and their property 20
Table 3: Water use activities applied for the IWULA. 27
Table 4: Mean monthly rainfall, rain days and evaporation data for the site 30
Table 5: Mean monthly temperature data for 0476762 (Springs) 31
Table 6: Average wind speed and direction 31
Table 7 : Land use categories present in the survey area. 32
Table 8: Key performance areas and indicators 44
Table 9: Criteria used for the environmental risk assessment 45
Table 10: Significance Rating 46
Table 11: Risk Assessment table for Welgelegen Colliery 47
FIGURES
Figure Figure Description Page
Figure 1: Welgelegen Colliery Locality Map 17
Figure 2: Location Map of Welgelegen Colliery 18
Figure 3: Quaternary Drainage Regions 19
Figure 4: Water sampling location 34
Figure 5: Delineated wetlands in study areas 38
Figure 6: Wetland classification within the study area 40
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 7
APPENDICES
Appendix No: Appendix Description
Appendix 1 Surface water Study (Update)
Appendix 2 Groundwater (Update)
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 8
LIST OF ABBREVIATIONS
Abbreviation Explanation BA Basic Assessment BOD Biochemical oxygen demand B-BBEE Broad Based Black Economic Empowerment Critical Biodiversity Area CBA
COD Chemical Oxygen Demand CSM Conceptual Site Model DWS Department of Water and Sanitation DEM Digital Elevation Model EC Electrical Conductivity EIA Environmental Impact Assessment EIR Environmental Assessment Report EIS Ecological Importance & Sensitivity GPT Geo Pollution Technologies GN704 Government Notice 704 HDPE High Density Polyethylene IWWMP Integrated Water and Waste Management Plan IWUL Integrated Water Use Licence IWULA Integrated Water Use Licence Application IWRS Integrated Water Resources Strategy MAP Mean Annual Precipitation MAR Mean Annual Runoff MBSP The Mpumalanga Biodiversity Sector Plan MTPA Mpumalanga MWP Mine Work Programme NEMWA National Environmental Management Waste Act NEMA National Environmental Management Act NWA National Water Act PCD Pollution Control Dam PES Present Ecological Status RSA Republic of South Africa RDM Resource Directed Measures WAR Wetland Assessment Report TDS Total Dissolve Solids R.O.M Run of Mine SR Scoping Report STRM Shuttle Radar Tomography Mission SHE Safety, Health and Environment
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 9
EXECUTIVE SUMMARY
Geovicon Environmental (Pty) Ltd has been appointed by Iyanga Mining (Pty) Limited to conduct an Integrated Water Use License Application for the water transfer pipeline that will cross over the wetland systems occurring between the Eastern and Northern section of the Welgelegen operations. The application will also include an extension of the opencast pit that will occur in a regulated area in of the Welgelegen Northern Section. Iyanga Mining (Pty) Limited was granted a mining right for the existing Welgelegen Colliery situated on a several portions of the farm Welgelegen 221 IR and portion 3 of the farm Vanggatfontein 250 IR, in terms of the Mineral and Petroleum Resources Development Act (MPRDA), 2002 (Act No. 28 of 2002), all situated within the Magisterial District of Delmas, Mpumalanga Province. The mining right areas held under Welgelegen Colliery are subdivided into three additional mining areas, the Southern mining section, Northern mining section and the extension of the Eastern mining section. This document concerns Welgelegen Colliery in its entirety. Currently the Welgelegen Colliery is operational, extracting coal from the North Section, through opencast mining method using the rollover technique. This report concerns the proposed opencast pit expansion to occur on the Northern Section and water transfer pipeline that pumps water from the pollution control dam on the Eastern Section to the pollution control dam at the Northern Section for reuse at the coal beneficiation plant. The report (Brief Application Report) provides a site specific, implementable, management plan, addressing all the identified issues relating to proposed activities at the Welgelegen Colliery. Iyanga Mining (Pty) Limited has also been authorised to conduct several activities that have been described under Section 21 of the National Water Act (NWA), 1998 (Act No. 36 of 1998) as water uses which include; taking water from a water resource; impeding or diverting the flow of water in a watercourse; disposing of waste in a manner which may detrimentally impact on a water resource; altering the bed, banks, course or characteristics of a watercourse; removing, discharging or disposing of water found underground if it is necessary for the efficient continuation of an activity or for the safety of people. These authorisations were issued under two integrated water use licences. However both licenses do not include extension of the opencast pit into the regulated area and the transferring of water using the pipeline and a new water use license had to be applied for to authorise the following water uses:
Section 21 (c): Impeding or diverting the flow of water in a watercourse; Section 21 (i): Altering the bed, banks, course or characteristics of a watercourse.
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 10
SECTION ONE
______
Introduction
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 11
1. INTRODUCTION
1.1 W H O I S D EVELOPING THE IWUL APPLICATION
Geovicon Environmental (Pty) Limited P.O. Box 4050 MIDDELBURG, 1050 Tel: (013) 243 5842 Fax: (013) 243 5843 Contact: Mr. O.T. Shakwane
Geovicon Environmental is a geological and environmental consulting company. The company was formed during 1996, and currently has twenty years’ experience in the geological and environmental consulting field. Geovicon Environmental has successfully completed consulting projects in the Mining sector (coal, gold, base metal and diamond), Quarrying sector (sand, aggregate and dimension stone), Industrial sector and Housing sector. Geovicon Environmental has undertaken contracts within all the provinces of South Africa, Swaziland, Botswana and Zambia. During 2001 Geovicon Environmental entered the field of mine environmental management and water monitoring.
Geovicon Environmental is a Black Economically Empowered Company with the BEE component owning 60% of the company. Geovicon Environmental has three members i.e. O.T Shakwane, J.M Bate and T.G Tefu.
Mr. O.T Shakwane obtained his BSc (Microbiology and Biochemistry) from the University of Durban Westville in 1994, and completed his honours degree in Microbiology in 1995. Mr O.T Shakwane has also completed short courses on environmental law and environmental impact assessment with the University of North West’s Centre for Environmental Management. He has worked with the three state departments tasked with mining and environmental management i.e. Department of Water and Sanitation (Gauteng and Mpumalanga Region), Department of Mineral Resources (Mpumalanga Region) and Department of Agriculture, Conservation and Environment (Gauteng Region). Mr. Shakwane has been in the consulting field since 2004 and has completed various projects similar to this project as an environmental assessment practitioner. Mr. O.T Shakwane is registered as a Professional Natural Scientist in terms of the section 20(3) of the Natural Scientific Professions Act, 2003 (Act 27 of 2003). He is also a member of the International Association for Impact Assessment, South Africa.
Mr. T.G. Tefu is a geologist. He obtained his BSc. in geology at the University of Witwatersrand. He worked with several mining companies and was also employed by the Department of Mineral Resources’ Environmental Management directorate. Mr. Bate, founder of Geovicon Environmental (Pty) Limited, is used by the company on an ad hoc (consultancy) basis. He is also a qualified geologist. He obtained his BSc (geology) from the
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 12
Potchefstroom University for CHE in 1993, and completed his honours degree (cum Laude) in geology in 1994. He obtained his MSC (cum Laude) in 1995.
Over the past years Geovicon Environmental has formalised working relationships with companies that offer expertise in the following fields i.e. Geohydrology, Hydrology, Civil and Geotechnical Engineering, Geotechnical Consultancy, Survey and Mine Planning, Wetland, Soil & Land Use Consultancy.
1.2 W H O W I L L E VALUATE THE IWULA?
In an effort by Iyanga Mining (Pty) Ltd to legally carry out the water use activities at the Welgelegen Colliery, a water use license application is submitted to the Department of Water and Sanitation (DWS). After the submission of the water use licence application, the Department of Water and Sanitation will evaluate the submitted information and based on the outcome of the evaluation Department of Water and Sanitation will decide whether or not to authorise the water use activities applied for by Iyanga Mining (Pty) Ltd.
1.3 L E G A L R EQUIREMENTS
Pro-active management of environmental impacts is required from the outset of mining activities. Internationally, principles of sustainable environmental management have developed rapidly in the past few years. Locally the Department of Water and Sanitation (DWS) and the mining industry have made major strides together in developing principles and approaches for the effective management of water within the industry. This has largely been achieved through the establishment of joint structures where problems have been discussed and addressed through co-operation.
The Bill of Rights in the Constitution of the Republic of South Africa, 1996 (Act 108 of 1996) enshrines the concept of sustainability; specifying rights regarding the environment, water, access to information and just administrative action. These rights and other requirements are further legislated through the National Water Act (NWA), 1998 (Act 36 of 1998). The NWA provides the DWS with the mandate to protect, use, develop, conserve, manage and control the country’s water resources in an integrated manner. The latter is the primary statute providing the legal basis the development of tools and means to ensure that the above-mentioned mandate is achieved, which will ultimately lead to water management in South Africa and ensuring ecological integrity, economic growth and social equity when managing and using water. One of these tools is the authorisation of water use as defined in Chapter 4 of the National Water Act, 1998 (Act 36 of 1998) (NWA). According to section 22 (1) of Chapter 4 of the National Water Act, 1998 (Act 36 of 1998), no person may use water without a proper authorisation from the responsible authority, which in this case is the DWS. Section 21 further describes activities that constitute water uses.
Further to the above, the NWA introduced the concept of Integrated Water Resource Management (IWRM), comprising all aspects of the water resource, including water quality, water quantity and the aquatic ecosystem quality (quality of the aquatic biota and in-stream and riparian habitat). The IWRM approach provides for both resource directed and source directed measures.
The integration of resource and source directed measures forms the basis of the hierarchy of decision- taking aimed at protecting the resource from waste impacts. Policies have been developed to assist mines in preparing reports that will ensure that their operations are compliant to the relevant requirements.
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 13
Operational policies and guidelines, which describe the rules applicable to different categories and aspects relating to waste discharge and disposal activities, are one of the instruments used by the DWS to prevent and manage impacts by mining activities on water resources, which are integrated in the water use authorisation processes.
In addition to the NWA, the following key legislation is also relevant to the IWULA processing:
The National Environmental Management Act (NEMA), No 107 of 1998 as amended
Minerals and Petroleum Resources Development Act, 2002 (Act 28 of 2002)
Mine Health and Safety Act (MHSA), No 29 of 1996, as amended
National Environmental Management Biodiversity Act (NEMBA), No 10 of 2004.
National Environmental Management Waste Act (NEMWA), No 59 of 2008.
National Environmental Management Air Quality Act (NEMAQA), No 39 of 2004.
1.4 P URPOSE OF THIS IWUL APPLICATION
This report addresses the requirements of the National Water Act, Act 36 of 1998. It is written to meet the technical requirements for the applied water uses in that it indicate in detail the intended water uses and the potential impacts the water uses applied for could have on the water resources. It outlines the measures that must be taken to avoid, minimise, rectify, reduce or offsets the effects of the negative impacts and to enhance effects of the positive impacts.
The aim of this Report is therefore to:
Provide information on the intended water uses;
Show how authorities and interested and affected parties have and will in future be afforded the opportunity to contribute to the project, and to indicate the issues raised and the responses to those issues;
Describe the baseline water and associated environment;
Describe water management measures that will be undertaken by the mine; and
Give a motivation for the water uses applied for.
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 14
SECTION TWO
______
Project Background & Context
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 15
2. PROJECT BACKGROUND AND CONTEXT
2.1 T H E AP P L I C A N T (IY A N G A M I N I N G (PTY) L TD, W E L G E L E G E N C OLLIERY )
Iyanga Mining (Pty) Ltd conducts mining at the Welgelegen Colliery situated on several portions of the farm Welgelegen 221 IR and portion 3 of the farm Vanggatfontein 250 IR. Iyanga Mining (Pty) Ltd was issued a mining right. (Ref. No: MP 30/5/1/2/2/443 MR) by the Department of Mineral Resources (DMR) (Mpumalanga Regional Office) in terms of section 102 of the MPRDA, 2002 (Act No. 28 of 2002). An amendment of the mining right was done which has resulted in Welgelegen Colliery being subdivided into three additional mining areas, the Southern mining section, Northern mining section and the Eastern mining section.
Iyanga Mining (Pty) Limited also obtained water use licences for its operations. The company has now lodged an application for a new water use license for a pipeline that will cross over the wetland systems occurring between the Eastern and Northern section as well as the extension of the current opencast pit into the regulated of the Welgelegen operations interms of the NWA, 1998 (Act No. 36 of 1998).
2.2 T H E A PPLICANT ’ S E NVIRONMENTAL C ONSIDERATIONS
Iyanga Mining (Pty) Limited environmental policy subscribes to best practice in environmental management. This target has been achieved and maintained for the Iyanga Mining (Pty) Limited. The following environmental considerations apply at the Welgelegen Colliery:
Conserve and protect environmental resources through, amongst others the efficient use of energy and water, minimising waste and reducing pollution.
Prevent or minimise adverse impacts arising from our operations.
Commit to open communication with employees, local contractors, suppliers, investors, business partners and other interested parties to encourage an environmentally responsible culture that reflects the intent of this policy.
Comply with environmental legislation and other requirements to which we subscribe and develop a culture of improvement.
2.3 O VERVIEW OF THE P ROJECT
2.3.1 Name of the Applicant Iyanga Mining (Pty) Limited
2.3.2 Name of Mine Welgelegen Colliery
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 16
2.3.3 Name of the Project Welgelegen Colliery Opencast pit extension and water transfer pipeline
2.3.4 Address of the Applicant P. O. Box 439 Witbank 1035
2.3.5 Contact Person Ms. Pamela Mqulwana
2.4 D ESCRIPTION OF THE P R O P E R T Y
2.4.1 Name of the Property
The Iyanga Mining (Pty) Limited water uses will fall on certain portions of Welgelegen 221 IR.
2.4.2 Magisterial District & Regional Services Council
District Municipality: Delmas District Municipality Local Municipality: Victor Khanye Municipality
2.4.3 Direction and Distance nearest Towns
Table 1: Direction and Distance to Nearest Towns
TOWN DIRECTION DISTANCE (KM)
Delmas West 17km Ogies East 22km
2.4.4 L o c a t i o n The Welgelegen Colliery is situated 17 kilometres west of Delmas in the Mpumalanga Province. The mine falls within the Victor Khanye Local Municipality, which forms part of the Delmas Municipality. See Figure 1 below:
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 17
Figure 1: Welgelegen Colliery Locality Map
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 18
Figure 2: Location Map of Welgelegen Colliery
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 19
2.4.5 Name of River Catchments The Welgelegen Colliery is located in the Olifants Water Management Area (WMA 2). Within the water management area, the proposed water transfer pipeline falls within the Wilge River catchment area, which is demarcated as tertiary drainage region B20. Welgelegen Colliery falls into quaternary drainage region B 20 E. Figure 2 depicts the location of the project area in relation to the quaternary drainage regions within the Wilge River catchment. The Wilge River eventually drains into the Olifants River upstream of the Loskop Dam.
Figure 3: Quaternary Drainage Regions
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 20
2.4.6 Name and Address of Direct Land Owners Table 2 below describes and depicts the properties on which the water uses applied for the Welgelegen Colliery falls under.
Table 2: Description of immediate and adjacent landowners and their property
Farm Portion Surface Right Owners Welgelegen 221 IR Portion 6 & 8 Farm House Holding (Pty) Ltd Portion 3 Copperzone 139 (Pty) Ltd Portion 12 Truter Boerdery Trust
2.5 I Y A N G A M I N I N G (PTY) L TD: W E L G E L E G E N C O L L I E R Y M E T H O D S TATEMENT
2.5.1 Construction Phase The following mine relate activities will be undertaken during the construction phase of the extension project, namely:
Topsoil, subsoil and overburden material from areas to be mined within the proposed expansion area will be stripped/removed and used for the rehabilitation of the preceding opencast pits. Note that the proposed opencast expansion will occur within an existing opencast and hence will be a continuation of the existing cuts. No initial box cut will be required for the proposed project. Access to the target coal seams within the first cut of the expansion area will be via the preceding cuts.
The construction phase of the pipeline system will cover as little space as possible complying with the relevant legal requirements. All necessary equipment will be assembled onsite and infrastructures will be placed for the duration of the mine.
2.5.2 Operational Phase The Welgelegen Colliery is currently operational mining coal using an opencast mining method, the extension will also be conducted as a continuation of the opencast mining method into the regulated area of portion 12 of the farm Welgelegen 221 IR. Following the removal of the extractable coal reserves, material from successive cuts will be used to backfill preceding cuts and each cut will be systematically filled with overburden first, subsoil second and topsoil lastly. Overburden from the next cut will be drilled, blasted and placed in the first cut, subsoil from the third cut will be used to cover the overburden placed in the first cut, and topsoil from the fourth cut will be placed over the subsoil in the first cut. The R.O.M from the opencast mining area will be transported by dump trucks along the existing haul roads, which connect to the existing coal stockpiling area.
The pipeline will be operated such that water is pumped in between the Welgelegen Operations without any negative impacts on the water resources. The pipeline system will be monitored on regular basis, to ensure that possible damages are repaired promptly after discovery.
2.5.3 Decommissioning/ Closure Phase Since concurrent rehabilitation will be undertaken during the operational phase, only the final voids will require rehabilitation. Rehabilitation of the voids will include the following i.e. the hards, subsoil and topsoil overburden stockpiled during the construction phase of the opencast project will be used to backfill the final voids. Method
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 21
of material placement will be placement of hards overburden first, followed by subsoil material and finally layer of topsoil. The final void will be filled to surface and shaped to ensure that the area is free draining. Infrastructures such as pumps and pipelines for the water transfer will be removed from the site during the decommissioning/closure phase.
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 22
SECTION THREE
______
Legal Assessment
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 23
3. LEGAL ASSESSMENT
This section of this report dwells much on the legal assessment associated with the water use application for the recommended water management system at the Welgelegen Colliery.
3.1 N A T I O N A L W A T E R A CT
According to the NWA, 1998 (Act No. 36 of 1998), the DWS has an overall responsibility over water resource management in the Republic of South Africa (RSA), which includes the allocation and use of water in the interest of the public. In view of the above, a person is only entitled to use water if the water use is permissible under the NWA.
3.1.1 Applicable sections Section 21: Water Use Section 21 of the NWA, 1998 (Act No. 36 of 1998) defines water use into eleven different uses which include: taking water from a water resource; storing water; impeding or diverting the flow of water; engaging in a stream flow reduction activity; engaging in a controlled activity; discharging of waste or water containing waste into a water resource; disposing of waste in a manner which may detrimentally impact on a water resource; disposing of water containing waste or which has been heated; altering the bed, banks, course or characteristics of a watercourse; removing of water found underground if it is necessary for efficient continuation of an activity and using water for recreational purposes.
Section 22: Permissible Water Uses Section 22 of the NWA, 1998 (Act No. 36 of 1998) gives conditions, limitations, restrictions, prohibitions, standards and practises that must be adhered to by any person who uses water in RSA. In view of this section of the act, Iyanga Mining (Pty) Limited is applying for a water use licence in order to undertake the water uses at their Welgelegen Colliery.
3.1.2 Summary of Relevant Exemptions Existing Lawful Water Uses In terms of Section 32 of the NWA, an Existing Lawful Water Use (ELWU) is defined as follows:
“Water use which has taken place at any time during a period of two years immediately before the date of commencement of the Act (1 October 1996 to 30 September 1998) and which was authorised by or under any law which was in force immediately before the date of commencement of this Act, or which has been declared an existing lawful water use in terms of Section 33 of the Act”. No existing lawful water use applicable at the proposed water activities at the Colliery.
3.1.3 Compliance with Section 27 of the National Water Act Section 27 of the National Water Act, Act 36 of 1998 sets out factors that should be considered by the Department of Water and Sanitation before issuing water use licenses. This section of the report will describe in detail the relevancy of the above-mentioned factors in relation to the water uses that are applied for and how the mine will comply with the requirements of section 27 of the National Water Act, Act 36 of 1998.
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 24
Section 27(1)(a): Existing lawful use Section 32(1)/(2) of the National Water Act, 1998 (Act 36 of 1998) gives a definition of an existing lawful water use. Based on the above section, any water use which has taken place at any time during the period of two years immediately before the date of commencement of the National Water Act, 1998 and which was authorised under any law which was in force immediately before the date of commencement of the National Water Act, 1998 (Act 36 of 1998) is an existing lawful water use.
Assessment of the Iyanga Mining (Pty) Ltd’s application, indicate that it will be constructed after the year 1998, hence there will be no existing lawful water use.
Section 27(1)(b): Redressing results of past discrimination A stable workforce, representing every aspect of South Africa’s demographics is currently under employment at the Iyanga Mining (Pty) Limited. The expansion of the pipeline and construction of the pipeline systems will create and sustain job opportunities at the mine since a contractor will be deployed for the duration of the project.
Section 27(1)(c): Efficient and beneficial use of water in the public interest Iyanga Mining (Pty) Limited commits to undertake its water uses in such a manner that the water resources in the vicinity where water will be discharged remains efficient and beneficial to the public. The public in this case will be the organisations that have been identified, the immediately adjacent land owners, the relevant state organs and the applicant.
Through the Water Use License, the water uses will be undertaken, managed and controlled in such a way to ensure that pollution and degradation of the water resources are minimised, hence protection of the water resource. This will further ensure that all water users within the sub catchment are not negatively impacted by the water uses applied for.
Section 27(1)(d): Socio-economic impact If water use is authorised: Iyanga Mining (Pty) Ltd believes in investing in communities beyond the workforce due to the following reasons i.e. it increases opportunities for outsourcing various activities, through increasing capacity of local business, it decreases the dependence of neighbouring communities on the mine; it increases the labour pool from which to secure local employees and it contributes towards a more stable community, particularly where development of human capital contributes to the increased quality of life and decreases poverty and associated ills. The successful implementation of the opencast expansion and water transfer pipeline will result in the mine having the ability to minimize the potential of contamination of water resources in the vicinity.
If water use is not authorised:
The authorization of the project will result in ensuring water resources are sustained without being negatively impacted for the duration of the mining activities at the Welgelegen Colliery. If the water uses
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 25
are not authorised the mine will not be able to continue with mining hence resulting in the early loss of job opportunities. This will not only affect the mine but the larger public.
Section 27 (1)(e): Applicable Catchment Management Strategy The Department of Water and Sanitation is responsible for the National Water Resource Strategy for South Africa. According to the National Water Act, 1998 (Act 36 of 1998), a Catchment Management Agency should be established for each water management area. The Catchment Management Agency will then be responsible for the Catchment Management Strategy for each water management area. The aim of the Catchment Management Strategy is to set principles for allocating water to existing and prospective water users, taking into account the protection, use, development, conservation, management and control of water resources.
Section 27(1)(f): Impact of mining activities on water resources and water users Iyanga Mining (Pty) Ltd is committed to managing impacts from their mining activities, to be within acceptable limits. An extensive monitoring programme including water monitoring has been specifically devised and is implemented for this project.
The monitoring data from this monitoring programme enables Iyanga Mining (Pty) Ltd to critically evaluate their water uses and make timely adjustments if and where necessary.
Section 27(1)(g): Class and resource quality objectives The South African Water Quality Guidelines are used for the Water Quality Objectives. The Minister of Department of Water and Sanitation is required to establish a classification system, and to determine the class and resource quality objectives for all or part of the resources considered to be significant. A determination of the preliminary class or resource quality objectives will be requested, which will include the water quality and quantity objectives for the reserve.
Section 27(1)(h): Investments already made and to be made The recommended changes in the water management system constitute an investment on behalf of Iyanga Mining (Pty) Ltd and is carried out in the interest of protecting the environment and to continue mining in an effective way.
Section 27(1)(i): Strategic importance of the water use to be authorised The commencement of the activities is of strategic importance and will ensure that there is no negative impacts on the environment and water resources in close proximity.
Section 27(1)(j): Water resource quality requirements for the reserve
Section 16 of the National Water Act, 1998 (Act 36 of 1998), requires that the Minister of the Department of Water and Sanitation to determine the Reserve for the river system before any license can be issued.
The Reserve consists of two parts: namely, the basic human need and the ecological reserve, which must be determined for all or part of any significant water resource. The Reserve is basically a specification of the amount of water that must be present in water resources as well as the quality of
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 26
the water for the water resource to remain ecologically healthy and to be able to provide water for basic human needs.
If a resource has not yet been classified, a preliminary determination of the Reserve may be made and later superseded by a new one. Once the Reserve is determined for a water resource, it is binding in the same way as the class and the resource quality objectives.
The determination of the reserve is the competency of the Department of Water and Sanitation, hence Iyanga Mining (Pty) Ltd will via the submission of this licence rely on DWS to determine the reserve for the mining area.
Section 27(1)(k): Duration of the water uses
The current estimated life of the proposed Welgelegen Colliery opencast expansion is one year. Note that this may results in the expansion of the life of mine of Welgelegen Colliery.
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 27
3.2 S U M M A R Y O F W A T E R U S E S APPLIED FOR
Table 3: Water use activities applied for the IWULA.
Water Use Property On Which Water Use Occurs Co-Ordinates
X Y
21 (c): Impeding or diverting the flow of water in a watercourse;
(i) The opencast pit expansion will be situated within a regulated area of a Portion 12 of the farm Welgelegen 221 IR. Start wetland in the vicinity. 26°07'15.31"S 28°50'11.67"E
End
26°07'0.13"S 28°50'36.09"S
(ii) Pipeline crossing at the Wilge River and associated wetlands. Portion 3, 6, 8 and 14 of the farm Welgelegen Start 221 IR. 26°06'45.93"S 28°52'07.25"E
End
26°07'54.11"S 28°51'11.21"S
21 (i): Altering the bed, banks, course or characteristics of a watercourse
(i) The opencast pit expansion will be situated within a regulated area of a Portion 12 of the farm Welgelegen 221 IR. Start wetland in the vicinity. 26°07'15.31"S 28°50'11.67"E
End
26°07'0.13"S 28°50'36.09"S
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 28
Water Use Property On Which Water Use Occurs Co-Ordinates
X Y
(ii) Pipeline crossing at the Wilge River and associated wetlands. Portion 3, 6, 8 and 14 of the farm Welgelegen Start 221 IR. 26°06'45.93"S 28°52'07.25"E
End
26°07'54.11"S 28°51'11.21"S
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 29
SECTION FOUR
______
Baseline Environmental Assessment
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 30
BASELINE ENVIRONMENTAL ASSESSMENT
This section of the report will give a description of the environment likely to be affected by the water use activities.
3.3 C LIMATE
The mean annual precipitation of the site is 669 mm. The mean annual evaporation of the site is 1677 mm (S-Pan). The monthly average rainfall, rainfall days, and evaporation are presented in Table 4. The Mpumalanga Highveld has distinct wet and dry seasons. 91% of the proposed Colliery’s mean annual rainfall falls between October and April inclusively. 68% of the area’s mean annual evaporation occurs in this period (Midgley et al., 1990).
3.3.1 Mean Monthly Rainfall No weather stations are located in close proximity to the proposed colliery. The closest weather stations are located in Witbank and Springs. Temperature data from the Springs weather station (Station number 0476762 A3) was analysed and a summary of the data is presented in Table 44 The temperature data spanned 2001 to 2010.
Table 4: Mean monthly rainfall, rain days and evaporation data for the site
Month Ave Rainfall (mm) Ave rain days Ave Evaporation (mm S-Pan) October 69.1 6.1 180.8 November 105.5 9 170.6 December 118.5 8.9 187.8 January 113.8 9.2 184.5 February 87 6.6 153.8 March 78.3 6 151.8 April 39.6 3.7 116.7 May 17.1 1.8 98.3 June 7.7 0.8 79.8 July 5.4 0.5 87.4 August 7.6 0.8 115.7 September 19.8 1.8 149.9
3.3.2 M ean Monthly Maximum and Minimum Temperatures No weather stations are located in close proximity to the proposed colliery. The closest weather stations are located in Witbank and Springs. Temperature data from the Springs weather station (Station number 0476762 A3) was analysed and a summary of the data is presented in Table 5. The temperature data spanned 2001 to 2010.
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 31
Table 5: Mean monthly temperature data for 0476762 (Springs)
Month Average daily minimum Average daily maximum temperature (ºC) temperature (ºC) January 15.2 26.5 February 14.5 26.3 March 12.3 25.0 April 8.8 23.2 May 3.7 20.8 June 1.1 18.4 July -0.1 18.7 August 3.5 21.6 September 7.8 25.5 October 11.3 26.4 November 13.6 25.3 December 14.8 26.9
3.3.3 Wind Direction and Speed at the Mine No data on the wind patterns is available for the proposed mining area. Owing to the location of the site, the gentle undulating topography and the non-existence of mountain ranges and ridges, no localised wind systems (topographically-induced) will be generated. Hence the wind patterns at the mine will conform to the regional wind patterns. The average wind speed and directions as recorded at the closest weather station are presented in Table 6.
Table 6: Average wind speed and direction
N NE E SE S SW W NW Month n v n v n v n V n v n v n v n v Jan 67 4.3 124 4.0 119 4.5 92 5.1 40 4.6 47 4.3 45 3.8 149 3.8 Feb 48 4.1 108 3.8 139 4.1 135 4.9 61 4.5 48 3.9 41 3.5 91 3.7 Mar 53 3.9 99 3.7 126 3.7 99 4.5 50 4.1 56 4.1 43 3.5 111 3.9 Apr 50 4.0 88 3.5 94 4.0 55 4.2 45 4.3 71 4.4 71 4.5 129 4.0 May 54 4.4 66 3.7 61 3.9 62 4.5 47 4.2 79 4.5 67 4.7 116 4.1 Jun 48 4.1 47 3.7 59 4.1 42 4.8 46 4.7 99 4.5 76 4.3 115 4.3 Jul 43 4.1 66 3.7 64 4.1 62 4.9 54 4.6 84 4.5 57 4.2 121 4.1 Aug 80 4.9 96 4.4 97 4.3 33 5.6 35 4.9 75 4.9 65 4.9 192 4.7 Sept 115 4.8 134 4.8 101 5.0 48 5.7 32 4.1 53 5.1 59 5.0 203 4.8 Oct 115 4.5 139 4.7 116 5.4 58 5.6 41 4.9 54 4.7 47 4.8 223 4.8 Nov 105 4.4 135 4.4 110 5.0 56 5.3 37 4.9 45 4.6 55 4.3 229 4.7 Dec 91 4.2 138 4.1 102 4.8 55 4.9 35 4.5 47 4.9 55 4.2 194 4.2 Avg 72 4.4 103 4.1 98 4.4 66 4.9 44 4.5 64 4.5 57 4.4 156 4.4
3.3.4 Extreme weather conditions Thunderstorms occur frequently during summer (rainy season) and are usually accompanied by lightning, heavy rain, strong winds and occasional hail. Storms are localised and rainfall can vary markedly over short distances. An average of six hail incidents per annum can be expected at a
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 32
particular site. Frost occurs in the winter months, peaking with an average occurrence of nine days in June.
3.4 T OPOGRAPHY
The topography can normally be used as a good first approximation of the hydraulic gradient in an unconfined aquifer. The area is characterised by a gentle undulating topography and in the area of the proposed mining site the slope is more or less in the order of 1:125 (0.008).
3.5 S OILS
Pedoplan International consultants were commissioned by Geovicon Environmental (Pty) Limited to conduct a soil-landform assessment. The purpose of the study was to supply soil-landform data and interpretations to inform an impact assessment process. The survey was conducted in accordance with standard procedures for detailed investigations. The objectives of the survey were as follows:
To conduct a detailed assessment of the soils-landform resources, comprising identification, description, classification and mapping of the soil-terrain types and assessing their attributes relating to agricultural potential, the potential for other land uses, susceptibility to erosion and topsoil quality.
To identify pre-mining land uses.
To assess the land capability of soil, terrain and climate combinations.
To identify and demarcate wetland zones from a soil-landform perspective.
To assess the impact of opencast coal mining on the soil-landform resources and propose mitigation measures.
3.6 L A N D U S E S
The cultivated fields were all planted to maize, some of it under centre pivot irrigation. Refer to Table 7 below for current land uses in and around the mining area.
Table 7 : Land use categories present in the survey area.
LAND USE AREA CURRENT LAND USE CODE ha % Cultivation (maize) (limited area under centre pivot A 1180.97 52.33 irrigation) B Grassed waterways 15.07 0.67 C Old lands; used for grazing 27.90 1.24 D Grazing of natural vegetation; some areas unused 913.25 40.46 E Previously mined area with incomplete rehabilitation 53.11 2.35 F Homestead or workers’ housing and facilities 21.40 0.94 G Unused (pans with water) 14.45 0.64 H Farm dams 15.64 0.70 I Gravel pits 3.40 0.15 J Public roads 11.82 0.52 Total 2257.01 100.0
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 33
3.7 S U R F A C E W ATER
Surface water study was conducted by specialists prior to the commencement of the mining activities at the Welgelegen Colliery. This report will be attached as Appendix 1 of this report.
3.7.1 Regional and Local Setting The Welgelegen Colliery is located in the Olifants Water Management Area (WMA 2). Welgelegen Colliery falls into quaternary drainage region B 20 E within the Wilge River catchment as show in Figure 2 above.
3.7.2 Baseline Hydrology Catchment Characterisation The Welgelegen Colliery falls in the Olifants Water Management area. The mining activities fall within the Wilge River catchment area, which is demarcated as tertiary drainage region B20. Welgelegen Colliery falls into quaternary drainage region B 20 E. The Wilge River eventually drains into the Olifants River upstream of the Loskop Dam.
3.7.3 Surface Water Quality Geovicon Environmental (Pty) Ltd conducts water quality monitoring at the Welgelegen Colliery at various sampling points. The location of all monitoring points are indicated in the Figure 3 below: The following variables are analysed i.e. Conductivity, pH, Nitrates, Chlorides, Sulphate, Fluoride, Sodium, Potassium, Calcium, Magnesium, Aluminium, Iron, Manganese and Nitrate.
3.7.4 Water Quality Analysis The water quality recorded, at all the monitoring points on Welgelegen Colliery indicate that the water management measures utilised on the mine are effective to prevent contamination of the natural water system. Based on the latest results (March 2020), it is evident that Welgelegen Colliery is not currently giving rise to large amounts of contamination of the Wilge River, or impacting on any potential downstream water user.
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 34
Figure 4: Water sampling location
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 35
3.8 G ROUNDWATER
If not properly maintained and managed, the proposed activities at the Welgelegen Colliery can potentially impact on the groundwater regime. An updated geohydrological study was conducted within and around the mining right area for the mining activities of Iyanga Mining (Pty) Ltd. The geohydrological assessment was compiled by Geo Pollution Technologies – Gauteng (Pty) Ltd (Appendix 2).
3.8.1 R egional Geohydrology The area is characterised by consolidated sedimentary layers of the Karoo Supergroup. It consists mainly of sandstone, shale and coal beds of the Vryheid Formation of the Ecca Group and is underlain by the Dwyka Formation of the Karoo Supergroup. Jurassic dolerite intrusions occur throughout the area in the form of sills and outcrops is found throughout the whole area. Small outcrops of the Daspoort (shale and quartzite) and Hekpoort (andesite) formations are also found on the farm Welgelegen. The proposed opencast mining areas falls within the Witbank Coalfield, which extends from Belfast in the north- east to Springs in the south- west covering a surface area of approximately 9000 km2.
3.8.2 Aquifer Description
3.8.2.1 Unsaturated - Shallow, Regolith Aquifer
The main source of recharge into the shallow aquifer is rainfall that infiltrates the aquifer through the unsaturated (vadose) zone. Vertical movement of water is faster than lateral movement in this system as water moves predominantly under the influence of gravity. This aquifer is comprised of transported alluvium and in-situ weathered sediments and is underlain by consolidated sedimentary rocks (sandstone, shale and coal). Based on literature the hydraulic conductivity of this aquifer likely ranges between 10-3 and 1 m.day-16.
3.8.2.2 S a t u r a t e d – Fractured, Bedrock Aquifer
The host geology of the area consists of consolidated sediments of the Karoo Supergroup and consists mainly of sandstone, shale and coal beds of the Ecca Group. Groundwater movement is predominantly associated with secondary structures in this aquifer (fractures, faults, dykes, etc.). The average water level depth in the area ranges between 5 and 25mbgl. Borehole yields in the Vryheid Formation and Dwyka aquifers are generally low and can be expected to be less than 2 l/s. Groundwater quality in the area is also expected to be intermediate to excellent with EC values ranging from 34 to 57mS/m. Both the porosity8 and the hydraulic conductivity9 of the Ecca Group fractured aquifers are known to be low. The commonly expected values of porosity and permeability for the rock types present in the site area, are 0 – 30% (porosity) and 10-7 – 1 m.d-1 (hydraulic conductivity) respectively (Kruseman & de Ridder, 1994). Movement of groundwater in this aquifer will be preferential in secondary structures such as joints, faults and fractures. Dolerite intrusions in the form of dykes and sills are often encountered in these aquifers. These intrusions can serve both as aquifers and aquifuges. Thick, unbroken dykes inhibit the flow of water perpendicular to the dykes, forming (leaky) compartments in most instances. In contrast, the baked and cracked contact zones is normally highly conductive parallel to the dykes and these effectively interconnect the strata of the sediments both vertically and horizontally into a single aquifer, though highly heterogeneous and anisotropic unit on the scale of mining. These structures thus tend to dominate the flow of
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 36
groundwater in fractured aquifers. Unfortunately, their location and properties are rather unpredictable and expensive to define in sufficient detail. Their influence on the flow of groundwater is thus incorporated by using higher than usual flow parameters for the sedimentary rocks of the aquifer.
3.8.3 Hydrocensus The hydrocensus was done as a site familiarisation exercise and the collection of data from the study area and surrounding environments. It comprised a census of key boreholes, wells, springs and any other groundwater related information. During the hydrocensus, 5 boreholes were available for groundwater level measurement.
3.8.4 Water Quality Water samples were collected from several surface and groundwater points around the site during the latest monitoring event. The water results are compared with the maximum recommended concentrations for domestic use as defined by the SANS 241-1: 2015 target water quality limits. The SANS 241-1: 2015 standard is applicable to all water services institutions and sets numerical limits for specific determinants to provide the minimum assurance necessary that the drinking water is deemed to present an acceptable health risk for lifetime consumption.
3.9 R E S O U R C E C L A S S A N D R I V E R H EALTH
Stream bio-monitoring is the monitoring of organisms that can be seen with the naked eye (macro- invertebrates) that live in different water habitats (biotopes). These organisms are seen as water users. Macro-invertebrate taxa have specific ranges of tolerance to water quality variables and/or water pollutants, thus the presence or absence of a specific taxon or group of taxa is indicative of the state of the stream and its ability to support aquatic life. Macro-invertebrates are further good indicators of synergistic effects, and have the added advantage of being relatively tolerant to chemical spikes. Iyanga Mining (Pty) Limited has appointed Ecotone Freshwater Consultants CC to undertake bio-monitoring at the receiving water bodies in the vicinity of the proposed mining areas i.e. the Wilge river, its tributaries and associated wetlands. Monitoring points were positioned within the above mentioned water resources for the bio-monitoring programme.The bio-monitoring programme involves the monitoring of the following indeces i.e. invertebrates habitat assessment system, in situ water quality, water testing and latest South African Scoring System (SASS). monitoring programme will be conducted once during the summer season and once during the winter season, upstream and downstream of the proposed mining areas.
3.10 S E N S I T I V E L ANDSCAPES
Iyanga Mining (Pty) Ltd recognises that all streams and associated wetlands occurring in the vicinity of the mining right area should be treated as sensitive landscapes. The application is for the expansion of the current opencast mining pit in to a regulated area, a wetland in the Northern Section and a pipeline that will cross over the wetland system to the North Section of the Colliery.
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 37
3.10.1 Wetland Delineation Wetland delineation was conducted according to the Guidelines set out by the DWS (DWS, 2005). Wetlands delineations are based on scientifically defensible criteria, thus providing a tool to facilitate the decision making process regarding the assessment of the significance of impacts on wetlands that may be associated with the proposed developments.
Wetland delineation was done in combination with the wet soils delineation. In order to cover a representative area of the wetlands in the study area, several transect surveys were necessary. Areas in between these transects were also traversed by foot and spot surveys contributed to a more complete survey. Delineated wetlands are shown on the Figure 5 below.
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 38
Figure 5: Delineated wetlands in study areas
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 39
3.10.2 Wetland Classification Wetlands are described in terms of their position in the landscape, and the classification was done according to the wetland hydro-geomorphic setting (Kotze D. C., Marneweck, Batchelor, Lindley, & Collins, 2004). Aerial photos, 1:50 000 topographic maps, satellite photos and GPS points are used to guide on-screen delineation of wetlands in ArcView GIS 3.2.
Palustrine wetland types identified in the study area are valley bottom wetlands without a channel, valley bottom wetlands with a channel, hill slope seepage wetlands feeding a water course, hill slope seepage not feeding a water course, depressions (pans) and a floodplain system. A visual of the wetland classification done prior to commencement of mining at Welgelegen Colliery can be seen in Figure 6.
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 40
Figure 6: Wetland classification within the study area
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 41
3.11 S OCIO - E C O N O M I C E NVIRONMENT
3.11.1 Population Density, Growth and Location The Victor Khanye Local Municipality (VKLM) is situated on the western Highveld of Mpumalanga Province, covering a geographic area of approximately 1 567 square kilometres. The prominent towns and settlements in the Municipality include Abor, Argent, Delmas, and Brakfontein. The municipality is strategically located close to the metropolitan areas of Tshwane and Ekurhuleni to the west. The headquarters of the municipality are in Delmas. VKLM is currently characterised by an increase in mining and related activities in the Leandra area. In addition to mining (concentrating on coal and silica), other important sectors in this area are agriculture (a major provider of food and an energy source, i.e. maize); finance and manufacturing (capitalising on the area’s proximity to Gauteng).
Natural resources make a significant and direct contribution to the Nkangala District economy, which is “resource based” (i.e. coal, water, land capacity, geographical features, climate, and conservation areas, ecosystems and natural features).
The population of VKLM has grown significantly since 2001 increasing from 56 335 to 75 452, which represent a growth of 33, 9 % (Census, 2011). The highest population density occurs in the core urban area of Delmas and Botleng, with the rural wards recording the lowest.
3.11.2 Major Economic Activities and source of employment The VKLM Gross Domestic Product (GDP) is forecast to grow by 3.4% per annum up to and including 2016, although this is lower that the District and Province projections. The forecast is very optimistic if we consider that the historic growth rate in the period 1996-2011 remained relatively low at 2.0% per annum.
Agriculture, transport, community services, finance and mining will be the main contributors to the VKLM economic growth in the period up to 2016. The municipality is a major maize producing area. Annual maize production is calculated at between 230 000 and 250 000 metric tons. Mining activities are concentrated on coal and silica. About 3 million metric tons of coal and 2 million metric tons of silica are mined annually in the municipal area. The employment prospect is expected to improve over the medium term with additional jobs expected in the mining sector.
3.11.3 H o u s i n g The municipality has recorded a significant growth in the number of households units from 13 409 in 2001 to 20 548 in 2011, representing an increase of 53 %, as a result of the population’s exponential growth. However, the VKLM comprises only 5, 8 % of the total households in the Nkangala District Municipality.
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 42
3.11.4 Social Infrastructure Road infrastructure at Victor Khanye area was originally designed for low volume traffic. The traffic volume has increased due to growth within the industrial and farming sector. Sundra, Eloff, Leeupoort, Rietkol, Botleng and Delpark have inadequate storm water drainage systems and as a result houses are flooded during raining seasons. The estimated kilometre of Municipal roads and Provincial roads around Victor Khanye is 245 km and 170 km (excluding 50 km National Roads) respectively. According to the 2011 Census 96 % of households receive a regular service from the municipality and 76 % of which are beneficiaries to weekly scheduled kerb side waste collection services.
3.11.5 Water Supply Approximately 17 100 households out of 20 548 households (83, 2 %) have access to potable water on their stands, excluding rural areas. The municipal council has provided the majority of the households in rural areas with borehole water, with the balance serviced by water tanker. The lack of provision of minimum standards of water negatively impacts on environmental issues associated with inadequate levels of sanitation infrastructure, as most households without potable water are still reliant on pit latrines or septic tanks. At least 2 432
Of the households (11, 8 %) in VKLM have not been provided with standard basic levels of sanitation. Water supply in Victor Khanye, Botleng, Delpark and other Extensions are supplied by means of boreholes.
3.11.6 Power Supply Approximately 85.1% of households in the Victor Khanye Municipal area use electricity for lighting. The balance, mainly residents of the rural areas and farm dwellers use candles as a means of lighting. The electricity network within Victor Khanye Local Municipality is ageing and has become inefficient. The main electricity substation is under severe pressure and needs to be upgraded since the electricity demand is increasing. (Extract from the Review -2014/15 Integrated Development Plan Victor Khanye Local Municipality)
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 43
SECTION FIVE
______
Environmental Impact Assessment Process
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 44
ANALYSES AND CHARACTERISATION OF ACTIVITY
3.12 R I S K ASSESSMENT
3.12.1 Safety, Health, Environment and Quality Policy Iyanga Mining (Pty) Limited is committed to operating in a responsible manner in order to minimise all potential environmental impacts at the Colliery. Furthermore, the company also aims to ensure the health and safety and well-being of the employees and the local community.
To ensure this Iyanga Mining (Pty) Limited will:
. Comply with all relevant laws, regulations and standards regarding, safety, health and the environment.
. Constantly monitor the effects of the operational activities in order to prevent pollution to the environment.
. Ensure that open communication exists between all employees and affected parties.
. Ensure that all employees are competent in their areas of responsibility regarding safety, health and the environment at the operation.
3.12.2 Objective and S t r a t e g i e s The primary objectives are to:
. Identify all pollution sources.
. Contain and manage all ground and surface water pollution.
. Minimise impacts through effective implementation of mitigation measures for possible contamination or pollution of water resources.
. Ensure sustainable utilisation of water resources (re-use of mine affected water).
. Monitor surface and groundwater quality.
3.12.3 Key Performance Area and Indicators The table 8 below lists all the key performance areas and indicators that supports the implementation of the water management plan for the mine.
Table 8: Key performance areas and indicators
Surface water Pollution prevention Containment of mine polluted water and waste. Limit the extent of dirty water areas. Pollution minimisation Re-use dirty water for dust suppression Removal of excess water from the opencast pits to the existing pollution control dam
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 45
Water quality Conduct water quality monitoring on a monthly basis Compile water quality monitoring reports on a quarterly basis Groundwater Pollution prevention Containment of mine polluted water and waste. Limit the extent of dirty water areas. Pollution minimisation Removal of excess mine water Re-use water from the opencast pits for dust suppression Water quality Conduct groundwater monitoring on a quarterly basis Compile water quality monitoring reports on quarterly basis
3.12.4 Methodology Followed The environment impact risk assessment addresses the actions of the operations for Iyanga Mining (Pty) Limited and assesses the significance of the impact on the environment. The impact will then be described using the parameters specified in the tables below.
Table 9: Criteria used for the environmental risk assessment
THE STATUS OF THE IMPACT
Positive: A benefit to the holistic environment Negative: A cost to the holistic environment Neutral: No cost or benefit The probability of the impact Score Severe / beneficial effect Description
0 None The impact will not occur
1 Improbable Less than 15% sure of an impact occurring Between 15% and 40% sure of an impact 2 Low (probability) occurring Between 40% and 60% sure that the impact 3 Medium (probability) will occur Between 60% and 85% sure that the impact 4 Highly Probable will occur 5 Definite Over 80% sure that the impact will occur The duration of the impact Score Severe / beneficial effect Description 1 Short term Less than 2 years 2 Short to medium term 2-5 years 3 Medium term 6-25 years 4 Long term 26-45 years 5 Permanent 46 years or more The scale of the impact Score Severe / beneficial effect Description
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 46
0 None 1 Site Within the site boundary 2 Local Affects immediate surrounding areas Extends substantially beyond the site boundary but only affects the region or 3 Regional province 4 National Affects country Affects is beyond the country and possibly the 5 International world The magnitude of the impact Score Severe / beneficial effect Description Effects observable – environmental impacts 2 Minor reversible with time without human intervention Effects observable – impacts reversible with 4 Low rehabilitation Effects observable – affected area restored to 6 Moderate acceptable environmental state Extensive effects – irreversible alteration to the 8 High environment Extensive permanent effects with irreversible 10 Very high/Don’t know alteration
3.12.5 Significance of Possible Impacts The significance of the impacts is calculated by multiplying the consequence of the impact by the probability of the impact. Table 1011 below illustrates the methodology used to calculate the significance of the impact.
Table 10: Significance Rating
The consequences of the impact Consequence = Magnitude + Duration + Scale The significance of the impact Significance = Consequence x Probability Significance Score out of 100 Low 1 to 30 Medium 30 to 60 High 60+
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 47
Table 11: Risk Assessment table for Welgelegen Colliery
Description of the Environmental Nature of the Impact (risk) of Environment and Human
Management Mitigation Measure facility aspect Health
Positive/Negative/ ImpactNeutral Probability Duration Scale Magnitude SIGNIFICANCE/ RISK Mitigation Required CONSTRUCTION PHASE
Expansion of opencast Surface Water Exposure of soils during construction by the stripping of Neg 3 1 2 6 27 Y Storm water upslope of the stripped areas should be diverted around these mining pit into a regulated areas to limit the amount of storm water flowing over these areas. This must vegetation and soils may cause erosion, which may lead to area of a wetland in the be conducted as per the approved civil designs. vicinity of the Northern increased silt loads in surface water runoff. This may result Section. in the contamination of the clean water environment watercourse (tributary of the Wilge River). If allowed, the above impacts may result in the watercourse (tributary of the Wilge River) being negatively impacted.
Groundwater Diesel, oil and chemical spills, if allowed to occur, will result Neg 3 2 2 5 27 Y Ensure that all mine machinery and vehicles are maintained on protected in the pollution of the surface water runoff and the ground. groundwater regime through runoff contamination and seepage. Installation of the Pipeline Surface Water The sedimentation, which will be emanating from the Neg 3 1 2 2 15 Y Measures must be put in place to control impacts from the sediments, which can system to transfer water construction site during the construction of the pipeline include berms, settling ponds etc. from the Eastern Section system, will have negative impacts on the stream and the to the Northern Section. wetland area. These sediments will result to an increase in the turbidity of the water in the stream, which will affect the aquatic habitat of the wetland; hence important habitats may be lost. Groundwater Hydrocarbon based fluids from the construction vehicles and Neg 3 1 2 2 15 Y Any repairs or maintenance of construction vehicles must be undertaken on power generators may spill and seep into the ground and areas covered by tarpaulins. Used oils and grease must be taken away and potentially affect the ground water quality. disposed of properly. Waste Management Waste will be generated from the crew campsite and the Neg 3 1 2 2 15 Y Proper waste management will be conducted at the construction and crew construction site. campsites. Waste will be stored separately according to their classes. Waste bins and containers with enough capacity to hold the waste will be placed at the crew camp and construction sites. Chemical toilets will be used at the crew camp and construction site for the collection of waste. OPERATIONAL PHASE Systematic removal of Surface Water Quality Storm and seepage water accumulating and generated from Neg 2 1 3 6 20 Y coal from the opencast All dirty water from the mine will be diverted and captured within the opencast the opencast pits will likely be contaminated and will have a pits pit and then pumped into the pollution control dam. detrimental effect on the water quality in the streams if released. The release of dirty water from the opencast pit Ensure that mined out areas are rehabilitated and seeded to have well may if not properly controlled, result in the downstream water established vegetation cover. users’ water quality requirements being affected. These Freshly rehabilitated areas will be installed with energy dissipaters that will impacts will be most acute during the dry season when reduce the amount of silt settling entering the streams from the rehabilitated stream flows are low. areas. Runoff from the upslope area may enter the rehabilitated Rehabilitated areas must be monitored and maintained to avoid areas with opencast workings giving rise to an increased silted water, which if discharged, will enter and affect the clean water bare patches and erosion. environment.
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 48
Description of the Environmental Nature of the Impact (risk) of Environment and Human
Management Mitigation Measure facility aspect Health
Positive/Negative/ ImpactNeutral Probability Duration Scale Magnitude SIGNIFICANCE/ RISK Mitigation Required Surface Water Quantity Formation of a void during mining will result in loss of MAR Neg 5 1 2 6 45 Y Ensure that the operational coal covers as little space as possible during within the catchments. mining; hence rehabilitation must be conducted concurrently with mining to ensure that the mined areas are returned to free draining surfaces. Rehabilitated areas may show areas of localised water ponding and impaired drainage. Ensure that the rehabilitated areas maintain safe slopes and the area is free draining. Runoff from the upslope area may enter the rehabilitated opencast workings giving rise to an increased loss of surface Construct contours to reduce the velocity of runoff storm water and establish water. vegetation as soon as possible after completion of the soil placement and profiling. Establish vegetation as soon as possible after completion of the soil placement and profiling. All clean water runoff diversion systems will be maintained and a push up berm will be constructed upslope of the pit. This berm will divert runoff water from the pit area.
Groundwater Quality Carbonaceous material remaining from the removal of run of Neg 3 4 5 5 42 Y Reduce the exposure of the carbonaceous material to free oxygen. This will mine coal may cause acid mine drainage after rehabilitation be achieved by placing the carbonaceous material at the bottom of the of the opencast pit. This may cause more harm on the already damaged groundwater regime. opencast pit and backfill as fast as possible.
Groundwater Quantity During the operational phase, it is expected that the main Neg 3 2 5 5 36 Y Boreholes surrounding the opencast area (used by the mine for domestic and impact on the groundwater quantity will be dewatering of the monitoring purposes) must be monitored on a quarterly basis. This will surrounding aquifer and loss of groundwater contribution to catchment base flow. Water entering the mining pit will have determine the extent of the dewatering cone from the opencast pit and any to be pumped out to enable mining activities to continue. user affected must be compensated by the mine. This may cause a lowering of the groundwater table in and around the mine and hence loss of groundwater to Mining must be undertaken concurrently with rehabilitation. The last box cut catchment base flow. may be operational during mining, which will reduce the cone of depression.
Water Transfer Pipeline Surface Water Quantity If pumped water from the Eastern section is allowed to enter Neg 3 3 3 6 36 Y A maintenance procedure should be designed to prevent accidental spillages pumping water from the the Wilge River through pipe leaks, its tributaries and or leakages from the pipeline system will be used during the maintenance of Eastern Section to the associated wetlands, it will have an impact on the quantity. Northern Section the water transfer pipeline. Surface Water Quality If the pipeline is not properly managed and maintained, Neg 3 3 1 4 24 Y Maintenance of the pipeline will be conducted regularly to ensure that there discharged mine water may deteriorate the Wilge River, its are no leakages. tributaries and associated wetlands. Continuous surface water monitoring should be conducted monthly, mostly downstream of the pipeline crossing. Groundwater quality If the pipe is not well assessed and maintained, leakages will Neg 3 3 2 8 39 Y Maintenance of the pipeline will be conducted regularly to ensure that there result into groundwater quality contamination. are no leakages. Groundwater quantity Seepages from leaks will gradually impact the groundwater Neg 3 3 1 4 24 Y Maintenance of the pipeline system will be conducted regularly to ensure that level. there are no leakages. DECOMMISSIONING PHASE
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 49
Description of the Environmental Nature of the Impact (risk) of Environment and Human
Management Mitigation Measure facility aspect Health
Positive/Negative/ ImpactNeutral Probability Duration Scale Magnitude SIGNIFICANCE/ RISK Mitigation Required Rehabilitation of the During the decommissioning phase, disturbed surface will Neg 4 1 2 4 28 Y Divert all runoff from any areas with loose material to pollution control Opencast Expansion final be removed of carbonaceous build-up material and structures. Note that the pollution control structure will remain until it can be voids rehabilitated. Thus run off from the removed carbonaceous proven that the area does not generate any polluted water. material could cause pollution of the nearby water Dirty water diversion trenches will be kept in place until all dirty areas are environment and may cause erosion. rehabilitated. All temporarily impacted areas must be rehabilitated and restored to the approved after mining land capability condition as per the mine’s Rehabilitation Plan; Only stockpiled and topsoil from the immediate area must be used for rehabilitation; A suitably qualified individual/botanist should conduct a closure audit to ensure rehabilitation has been undertaken in a satisfactory manner. Water transfer Pipeline Surface Water Quality/ Surface water run-off from the rehabilitation sites will Neg 4 1 2 6 36 Y No rehabilitation activities must be conducted outside these sites. and stream crossing Quantity generate excessive silts, and this may enter the clean water Any erosion channels developing must be repaired as soon as possible. environment. The contamination of the stream may results All rehabilitation areas must be profiled such that they are free draining. that will reduce the viability of the aquatic life in the stream Any repairs or maintenance of construction vehicles must be undertaken on and may render the stream not usable to the downstream areas covered by tarpaulins. users. The nearby stream and its wetland areas must be buffered from any of the rehabilitation activities. Continue with surface water monitoring.
Waste Management Waste will be generated at the rehabilitation sites and crew Neg 2 2 1 4 14 Y Proper waste management will be conducted at the rehabilitation sites and camp site. crew camp site. Waste will be stored separately according to their classes. Waste bins and containers with enough capacity to hold the waste will be placed at the crew camp and rehabilitation sites. Monitor illegal dumping and littering in the mine area. Groundwater quality Areas that have been used for the disposal facility for waste Neg 3 5 2 4 33 Y The mine must ensure that as much of the waste and fuel contaminated areas /quantity and hydrocarbon based fuels may have latent impacts on are removed and properly rehabilitated. the groundwater regime if the waste is not properly removed.
Potential hydrocarbon contamination of soils and ground Neg 3 5 2 4 33 Y Mine vehicles and machinery will be regularly serviced to reduce the risk of water. hydrocarbon leaks. Incidents should be reported and treated immediately in a reputable manner. AFTER CLOSURE PHASE (RESIDUAL IMPACTS)
Profiling of the area to Groundwater Quantity After closure, the water table will rise in the rehabilitated Neg 4 5 2 6 52 Y Remaining acid producing material should be placed as low in the pit as ensure free drainage and colliery to reinstate equilibrium with the surrounding Rehabilitation groundwater systems. However, the mined areas will have a possible to ensure fast flooding of the material. All mined areas should be large hydraulic conductive compared to the pre-mining flooded as soon as possible to bar oxygen from reacting with remaining pyrite. situation. This will result in a relative flattening of the groundwater table over the extent of the opencast mining The final backfilled colliery topography should be engineered such that runoff area, in contrast to the gradient that existed previously. is directed away from the colliery areas. The end result of this will be a permanent lowering of the The final layer (just below the topsoil cover) should be as clayey as possible groundwater level in the higher topographical area and a rise in lower lying areas. and compacted if feasible, to reduce recharge to the colliery.
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 50
Description of the Environmental Nature of the Impact (risk) of Environment and Human
Management Mitigation Measure facility aspect Health
Positive/Negative/ ImpactNeutral Probability Duration Scale Magnitude SIGNIFICANCE/ RISK Mitigation Required Quarterly groundwater sampling must be done to establish a database of plume movement trends, to aid eventual mine closure. Groundwater Quality Once the normal groundwater flow conditions have been re- Neg 4 5 2 8 60 Y Implement as many closure measures during the operational phase, while instated, polluted water can migrate away from the conducting appropriate monitoring programmes to demonstrate actual rehabilitated areas. As some coal and discards will remain performance of the various management actions during the life of mine. in the mine, this outflow will be contaminated as a result of acid or neutral mine drainage. As sulphate is normally a significant solute in such drainage, it has been modelled as Mining should remove all coal from the colliery and separate acid forming and a conservative (non-reacting) indicator of mine drainage non-acid forming material. Deposit acid forming material at the base of the pit. pollution.
Water transfer Pipeline Surface water quality Once the groundwater flow conditions have been re- Neg 2 2 2 6 36 Y Monitor area for erosion and pooling and rehabilitate if necessary. Continue and stream crossing /quantity instated, polluted water can migrate away from the with water monitoring. rehabilitated areas. As the water is regarded as dirty water, this outflow will be. As sulphate is normally a significant solute in such drainage, it has been modelled as a conservative (non-reacting) indicator of mine drainage pollution.
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 51
MONITORING SYSTEM
3.13 M ONITORING
3.13.1 Surface Water Monitoring Mining and associated activities have a potential to detrimentally impact on the surface water environment. This is mainly due to the pollution point sources, which include the dirty water storage areas at the mine. Surface water monitoring is undertaken by Geovicon Environmental (Pty) Ltd at the mine at various sampling points which were sited strategically to ensure that the surface water bodies that occur in the vicinity of the proposed pipeline are monitored. Any deterioration of the surface water quality will be detected through this monitoring programme and measures will be taken to address the possible source of such pollution.
3.13.2 Groundwater Monitoring A groundwater monitoring programme has been developed and the mine has to adhere to the criteria mentioned below. As a result the system should be developed accordingly.
Source, plume, impact and background monitoring
A groundwater monitoring network should contain monitoring positions which can assess the groundwater status at certain areas. The boreholes can be grouped classification according to the following purposes:
Source monitoring: Monitoring boreholes are placed close to or in the source of contamination to evaluate the impact thereof on the groundwater chemistry.
Plume monitoring: Monitoring boreholes are placed in the primary groundwater plume’s migration path to evaluate the migration rates and chemical changes along the pathway.
Impact monitoring: Monitoring of possible impacts of contaminated groundwater on sensitive ecosystems or other receptors. These monitoring points are also installed as early warning systems for contamination break-through at areas of concern.
Background monitoring: Background groundwater quality is essential to evaluate the impact of a specific action/pollution source on the groundwater chemistry.
System Response Monitoring Network
Groundwater levels: The responses of water levels to abstraction are monitored. Static water levels are also used to determine the flow direction and hydraulic gradient within an aquifer. Where possible all of the above mentioned borehole’s water levels need to be recorded during each monitoring event.
Monitoring Frequency
In the operational phase and closure phase, quarterly monitoring of groundwater quality and groundwater levels is recommended. Quality monitoring should take place before after and during the wet season, i.e. during September and March. It is important to note that a groundwater-monitoring network should also be dynamic. This means that the network should be extended over time to accommodate the migration of
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 52
potential contaminants through the aquifer as well as the expansion of infrastructure and/or addition of possible pollution sources.
Monitoring Parameters
The identification of the monitoring parameters is crucial and depends on the chemistry of possible pollution sources. They comprise a set of physical and/or chemical parameters (e.g. groundwater levels and predetermined organic and inorganic chemical constituents). Once a pollution indicator has been identified it can be used as a substitute to full analysis and therefore save costs. The use of pollution indicators should be validated on a regular basis in the different sample position. The parameters should be revised after each sampling event; some metals may be added to the analyses during the operational phase, especially if the pH drops.
Physical Parameters:
Groundwater levels
Chemical Parameters:
Field measurements:
pH, EC
Laboratory analyses:
Major anions and cations (Ca, Na, Cl, SO4) Other parameters (EC) Physical Parameters:
Groundwater levels Chemical Parameters: Field measurements: pH, EC Laboratory analyses:
Anions and cations (Ca, Mg, Na, K, NO3, Cl, SO4, F, Fe, Mn, Al, & Alkalinity) Other parameters (pH, EC, TDS) Petroleum hydrocarbon contaminants (where applicable, near workshops and petroleum handling facilities) Sewage related contaminants (E.coli, faecal coliforms) in borehole in proximity to septic tanks or sewage plants
3.14 E NVIRONMENTAL M A N A G E M E N T P ERFORMANCE ASSESSMENT AND R EPORTING
This section will describe how the Iyanga Mining (Pty) Limited intends to ensure that the mitigation measures for the reduced impacts are undertaken and that their effectiveness is proven.
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
Integrated Water Use Licence Application: Iyanga Mining (Pty) Limited, Welgelegen Colliery Page 53
As part of the general terms and conditions for a mining right, and in order to ensure compliance with the approved environmental management programme, issued water use licences and environmental authorisations and to comply with the NEMA EIA Regulations, 2014, Iyanga Mining (Pty) Limited will undertake the following:
Conduct monitoring on a continuous basis;
Compile and submit relevant audit reports to the minister in which compliance or non-compliance with the approved authorisations is demonstrated.
The audit reports will as a minimum contain the following:
o Information regarding the period applicable to the performance assessment/audit
o The scope of the assessment/audit
o The procedure used for the assessment/auditing
o The interpreted information gained from environmental monitoring
o The evaluation criteria used during the assessment/auditing
o The results of the assessment/auditing; and
Recommendations on how and when non-compliance and deficiencies will be rectified.
COMPILED BY GEOVICON ENVIRONMENTAL (PTY) LTD IYANGA MINING (PTY) LIMITED
APPENDICES
APPENDIX 1
Update Surface Water Study
iLanda Water Services CC Reg. No.: CK2011/077571/23
PO Box 44961 Linden 2104 Johannesburg, South Africa
Tel +27 (0)83 408 3241 Fax +27 (0)86 552 0407 [email protected] http://www.ilandawater.co.za
REPORT ON
HYDROLOGICAL EVALUATION FOR THE WELGELEGEN OPEN CAST MINING OPERATIONS ON THE FARM WELGELEGEN 221 IR
Report No : 0122-Rep-001 Rev4
Submitted to:
Geovicon (Pty) Ltd 42 AG Visser Street Middleburg 1050
DISTRIBUTION:
Geovicon (Pty) Ltd iLanda Water Services CC – Library
March 2019 0122
Member: B Randell BSc Eng (Civil), PhD, PrEng. www.ilandawater.co.za March 2019 i 0122-Rep-001 Rev4
TABLE OF CONTENTS
SECTION PAGE
1 INTRODUCTION ...... 1 1.1 Study Objectives ...... 1 1.2 Scope of work ...... 1 1.3 Battery Limits ...... 2 2 REGIONAL SETTING ...... 2 3 LOCAL SETTING ...... 3 4 CATCHMENT DESCRIPTION ...... 3 5 BASELINE RAINFALL, EVAPORATION, TEMPERATURE AND WIND ...... 4 5.1 Mean Annual Precipitation and Evaporation ...... 4 5.2 Average Temperature and Wind Data Analysis ...... 5 5.3 Sources of Rainfall Data ...... 8 5.4 Sources of Evaporation Data ...... 8 5.5 Peak Rainfall Data ...... 8 5.5.1 Maximum Monthly Rainfall Data ...... 8 5.5.2 Peak 24-hr Rainfall Data ...... 8 6 BASELINE HYDROLOGY ...... 9 6.1 Mean Annual Run-off ...... 9 6.2 Normal Dry Weather Flows ...... 9 6.3 Flood Flow Analysis ...... 10 7 FLOODLINES ...... 11 7.1 Backwater analysis ...... 11 8 BUFFER ZONES ...... 12 9 WATER QUALITY ...... 13 9.1 Surface Water Users ...... 13 9.2 Sample Locations ...... 14 9.3 Baseline Water Quality Analysis ...... 15 9.3.1 Northern Tributary ...... 15 9.3.2 Western Tributary ...... 15 9.3.3 Eastern Tributary...... 16 9.3.4 Wilge River...... 16 10 IMPACT ASSESSMENT ...... 25 10.1 Project Description ...... 25 10.2 Methodology for Impact Assessment ...... 25 10.3 Impacts During the Construction Period ...... 26 10.3.1 Impacts due to topsoil stripping ...... 26 10.3.2 Impacts due to construction related pollution ...... 28 10.4 Impacts During the Operational Phase ...... 29 10.4.1 Impacts due to contaminated water discharge ...... 29 10.4.2 Loss of catchment yield ...... 30 10.4.3 Impacts due to wash bays and workshops ...... 32 10.4.4 Impacts due to burst water pipes ...... 33 10.4.5 Impacts due to extreme flooding ...... 34 10.4.6 Impacts due to vehicle fleet-related pollution ...... 35 10.5 Impacts During the Decommissioning Phase of the Project ...... 36 10.5.1 Impacts due to the removal of surface infrastructure ...... 36 10.6 Impacts After the Closure Phase of the Project ...... 37 10.6.1 Impacts due to open cast workings decant ...... 37
Member: B Randell BSc Eng (Civil), PhD, PrEng. www.ilandawater.co.za
March 2019 ii 0122-Rep-001 Rev4
11 REFERENCES ...... 39
LIST OF FIGURES
Figure 1: Study battery limits 2
Figure 2: Wilge River within the mining rights area 4
Figure 3: Average wind rose data (throughout the year) 6
Figure 4: Monthly wind rose data 7
Figure 5: Log Pearson Type 3 statistical fit to the annual maximum series 9
Figure 6: Floodlines on Eastern Tributary 11
Figure 7: Floodlines on Western Tributary 12
Figure 8: Surface water buffer zones for the Western and Eastern tributaries 13
Figure 9: Water sampling locations (groundwater points are excluded from this study) 15
LIST OF TABLES
Table 1: Mean monthly rainfall, rain days and evaporation data for the mining rights area .... 5
Table 2: Mean monthly temperature data for 0476762 (Springs) ...... 5
Table 3: Maximum monthly rainfall data (mm) ...... 8
Table 4: Peak 24-hr rainfall depths for the mining rights area ...... 8
Table 5: Normal dry weather flows (highlighted in bold text)...... 10
Table 6: Peak flows in the Wilge River and the three tributaries ...... 10
Table 7: Summary of water quality analysis (WS-01) ...... 17
Table 8: Summary of water quality analysis (WS-02) ...... 18
Table 9: Summary of water quality analysis (WDS1) ...... 19
Member: B Randell BSc Eng (Civil), PhD, PrEng. www.ilandawater.co.za
March 2019 iii 0122-Rep-001 Rev4
Table 10: Summary of water quality analysis (WDS2) ...... 20
Table 11: Summary of water quality analysis (SWMS) ...... 21
Table 12: Summary of water quality analysis (SWUS) ...... 22
Table 13: Summary of water quality analysis (WUS) ...... 23
Table 14: Summary of water quality analysis (PCD) ...... 24
Table 15:Loss of catchment yield ...... 31
LIST OF APPENDICES
None
REVISION TRACKING
Rev 0: Original document.
Rev 1: Floodlines and buffer zones added, impact assessment updated.
Rev 2: Addressed the need for floodlines on the Wilge River
Rev 3: Impact assessment amended
Rev 4: Mine layout changes and additional water quality information included
Member: B Randell BSc Eng (Civil), PhD, PrEng. www.ilandawater.co.za
March 2019 1 0122-Rep-001 Rev4
1 INTRODUCTION
Geovicon (Pty) Ltd (Geovicon) commissioned iLanda Water Services CC to do a surface water specialist study for the colliery on the farm Welgelegen 221 IS. This report details the results of the study, as well as recommendations coming from the work done.
1.1 Study Objectives
The study objectives are as follows: • Baseline hydrological analysis • Surface water impact assessment • Review and comment on baseline water quality.
This report constitutes the outcome of the specialist studies undertaken by iLanda Water Services CC, on behalf of Geovicon, related to the environmental impact of the colliery on the farm Welgelegen 221 IS.
1.2 Scope of work
The scope of work is summarised as follows:
• Hydrological analysis o Catchment delineation based on the Surveyor General’s 5m contours o Catchment characterisation o Climate and mean annual and monthly precipitation analysis o Maximum rainfall intensities o Mean annual run-off analysis, based on the Water Resources of South Africa, 2005 Study (WRC Report No TT 382/08) o Normal dry weather flows, based on the Water Resources of South Africa, 2005 Study (WRC Report No TT 382/08) o Flood flow analysis – the 50-year and 100-year flood peaks will be calculated in the three streams that flow through the mining rights area. • Surface water quality o Baseline surface water quality analysis and interpretation • Surface water use o Possible downstream users will be identified in terms of the headings of the South African Water Quality Guidelines • Impact assessment • Reporting o Compilation of a hydrological report which can be used as input into the final Water Use Licence Application
Member: B Randell BSc Eng (Civil), PhD, PrEng. www.ilandawater.co.za
March 2019 2 0122-Rep-001 Rev4
1.3 Battery Limits
The study battery limits are the mining rights area, shown in purple in Figure 1. All work is confined to these battery limits unless otherwise specified.
Figure 1: Study battery limits 2 REGIONAL SETTING
The colliery is located in the Mpumalanga Province of South Africa. It is located approximately 45 km south west of Emalahleni (Witbank), in the upper reaches of the Wilge River catchment. The Wilge River is a tributary of the Olifants River. This section of the Olifants River catchment is adjacent to the Witbank Dam catchment and discharges into the Loskop and Flag Boshielo Dams.
The Loskop and Flag Boshielo dams are located downstream of Witbank Dam and are an important source of domestic, irrigation and industrial water to their surrounding areas. The Olifants River is an international river, flowing through the Kruger National Park and into Mozambique. With the Olifants River flowing through the Kruger National Park, provision for meeting ecological requirements is one of the controlling factors for managing water resources throughout the Olifants River catchment.
Member: B Randell BSc Eng (Civil), PhD, PrEng. www.ilandawater.co.za
March 2019 3 0122-Rep-001 Rev4
The Wilge River catchment measures 4 360 km 2. The mean annual precipitation in this catchment is generally uniform with an average precipitation of approximately 670 mm, varying between 650 mm and 700 mm.
The mean annual evaporation (S-Pan) varies between 1 677 mm in the south western regions of the catchment and 1 800 mm in the north western regions of the catchment.
The natural vegetation in the catchment is predominantly grassland. Extensive irrigated and dry-land agricultural activities are prevalent, along with various forms of livestock farming. Power stations and mining activities occur in the Wilge River catchment, as do a number of small towns. These include Delmas, Bronkhorstspruit, Lionelton, Kendal, and New Largo.
3 LOCAL SETTING
The mining rights area is located in quaternary catchment B20E. It is located approximately 13 km south west of Kendal and 17 km east of Delmas.
Two small tributaries of the Wilge River flow through the mining rights area (refer to Figure 1). The Western tributary is perennial and flows generally in a north easterly direction through the central part of the mining rights area. The Eastern tributary is non-perennial and flows through the northern regions of the mining rights area. The Northern tributary flows past the northern end of the mining rights area.
4 CATCHMENT DESCRIPTION
The Western tributary catchment is undeveloped and consists mostly of impacted grasslands and dry land agriculture. The Eastern catchment has a small open cast mine in it. Mixed stockpiles are present, as well as the open pit, a run of mine stockpile area and two small unlined pollution control dams. The Northern tributary catchment is rural but is impacted by mining activities.
The topography is relatively flat. Localised areas have steeper slopes, particularly in the vicinity of the streams. The three tributaries are dammed with multiple farm dams on each tributary. The water courses of the two tributaries in the mining rights area are heavily reeded in places, particularly downstream of the farm dams. The lower reaches of the tributaries have a defined water course that is generally free of reeds. The flood plains are not well developed.
The Wilge River has a deeply incised channel within the mining rights area. The sides of the channel are well vegetated with woody vegetation. The base of the channel is relatively free of vegetation. The floodplain is not well-developed.
Member: B Randell BSc Eng (Civil), PhD, PrEng. www.ilandawater.co.za
March 2019 4 0122-Rep-001 Rev4
Figure 2: Wilge River within the mining rights area
5 BASELINE RAINFALL, EVAPORATION, TEMPERATURE AND WIND
5.1 Mean Annual Precipitation and Evaporation
The mean annual precipitation of the mining rights area is 669 mm. The mean annual evaporation of the mining rights area is 1677 mm (S-Pan). The monthly average rainfall, rainfall days, and evaporation rates are presented in Table 1. The Mpumalanga Highveld has distinct wet and dry seasons. 91% of the colliery’s mean annual rainfall falls between October and April inclusively. 68% of the area’s mean annual evaporation occurs during this period (Midgley et al., 1990).
Member: B Randell BSc Eng (Civil), PhD, PrEng. www.ilandawater.co.za
March 2019 5 0122-Rep-001 Rev4
Table 1: Mean monthly rainfall, rain days and evaporation data for the mining rights area Month Ave Rainfall (mm) Ave Rain Days Ave Evaporation (mm S-Pan) October 69.1 6.1 180.8 November 105.5 9 170.6 December 118.5 8.9 187.8 January 113.8 9.2 184.5 February 87 6.6 153.8 March 78.3 6 151.8 April 39.6 3.7 116.7 May 17.1 1.8 98.3 June 7.7 0.8 79.8 July 5.4 0.5 87.4 August 7.6 0.8 115.7 September 19.8 1.8 149.9 Mean Annual 669* 1677 * Note: The sum of the mean monthly rainfall depths does not necessarily equal the mean annual precipitation.
5.2 Average Temperature and Wind Data Analysis
No weather stations are located in close proximity to the colliery. The closest weather stations are located in Witbank and Springs. Temperature data from the Springs weather station (Station number 0476762 A3) was analysed and a summary of the data is presented in Table 2. The temperature data spanned 2001 to 2010.
Table 2: Mean monthly temperature data for 0476762 (Springs) Month Average daily minimum Average daily maximum temperature (ºC) temperature (ºC) January 15.2 26.5 February 14.5 26.3 March 12.3 25.0 April 8.8 23.2 May 3.7 20.8 June 1.1 18.4 July -0.1 18.7 August 3.5 21.6 September 7.8 25.5 October 11.3 26.4 November 13.6 25.3 December 14.8 26.9
Member: B Randell BSc Eng (Civil), PhD, PrEng. www.ilandawater.co.za
March 2019 6 0122-Rep-001 Rev4
Wind data from the Springs weather station (Station number 0476762 A3) was analysed and a summary of average wind speeds and directions is presented in Figure 3. The monthly breakdown of average wind speeds and directions is presented in Figure 4.
Figure 3: Average wind rose data (throughout the year)
Member: B Randell BSc Eng (Civil), PhD, PrEng. www.ilandawater.co.za
March 2019 7 0122-Rep-001 Rev4
Figure 4: Monthly wind rose data
Member: B Randell BSc Eng (Civil), PhD, PrEng. www.ilandawater.co.za
March 2019 8 0122-Rep-001 Rev4
5.3 Sources of Rainfall Data
Daily rainfall data was sourced from the CCWR (Computing Centre for Water Research, Natal University) rainfall database (gauge number 0677762 – Strehla). The gauge is located approximately 12 km south east of the site. The data is a complete record between 1/1/1920 and 31/5/2000, or just over 80 years. The data contains 379 patched records out of 29372 records, or 1.29%. This data was augmented by data purchased from the South African Weather Service. The combined data set is a complete record of 91½ years. The data is considered representative of the site and is of good quality.
5.4 Sources of Evaporation Data
The mean annual evaporation was sourced from the average evaporation for quaternary catchment B20E, documented in the Water Resources of South Africa, 2005 Study (Middleton and Bailey, 2009). Its monthly distribution was sourced from the Water Resources of South Africa Study data set, zone 4A (Midgley et al., 1990). The data is considered representative of the site.
5.5 Peak Rainfall Data
5.5.1 Maximum Monthly Rainfall Data
The maximum monthly rainfall data was distilled from the daily rainfall record (discussed in section 5.3) and is presented in Table 3.
Table 3: Maximum monthly rainfall data (mm) Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep 219.6 235 296.4 286.7 301 268.5 166.8 167.6 77.1 62.4 50.4 165.2
5.5.2 Peak 24-hr Rainfall Data
The peak 24-hr rainfall depths are presented in Table 4.
Table 4: Peak 24-hr rainfall depths for the mining rights area Recurrence Interval (year) 24 Hour Rainfall Depth (mm) 2 54 10 83 20 94 50 109 100 121 200 133
Member: B Randell BSc Eng (Civil), PhD, PrEng. www.ilandawater.co.za
March 2019 9 0122-Rep-001 Rev4
The daily rainfall record, discussed in section 5.3, was analysed and the annual maximum series was extracted from the data. This annual maximum series was statistically analysed to determine various T-year recurrence interval 24-hour storm depths. A Log Pearson Type 3 fit was selected as the most appropriate statistical fit. This fit is shown in Figure 5. The rainfall record is long, consists of good data, is representative of the mining rights area, and is suitable to be used to calculate peak rainfall presented in Table 4.
Figure 5: Log Pearson Type 3 statistical fit to the annual maximum series
6 BASELINE HYDROLOGY
6.1 Mean Annual Run-off
The mean annual run-off for the Wilge River up to the point where it leaves the mining rights area is 13.76 Mm 3. The mean annual run-off for the Western tributary is 0.56 Mm3. The mean annual run-off for the Eastern tributary is 0.22 Mm 3. The mean annual run-off for the Northern tributary is 0.33 Mm 3.
The catchment characteristics of the four catchments are similar to those of quaternary catchment B20E, so the mean annual run-off was scaled from the quaternary catchment run- off, based on relative catchment size. The flows for the three tributaries were calculated at their confluence with the Wilge River.
6.2 Normal Dry Weather Flows
The Eastern tributary is marked as a non-perennial river on the 50 000 topographical sheets. Dry weather flows are likely to be very low and will often be limited to sub-surface flow only. Average dry weather flows appear high but these are influenced by storm flow from occasional winter rainfall events.
Member: B Randell BSc Eng (Civil), PhD, PrEng. www.ilandawater.co.za
March 2019 10 0122-Rep-001 Rev4
The normal dry weather flows are based on the average monthly flows documented in the Water Resources of South Africa, 2005 Study (Middleton and Bailey, 2009) for quaternary catchment B20E. The flows were scaled based on relative catchment size. The dry weather flows for the three tributaries and the Wilge River are presented in Table 5. The dry weather flows have been highlighted in bold text.
Table 5: Normal dry weather flows (highlighted in bold text) Month Wilge River Western Eastern Northern mean monthly tributary mean tributary mean tributary mean flows monthly flows monthly flows monthly flows (m 3/month) (m 3/month) (m 3/month) (m 3/month) October 537 512 21 815 8 715 13 040 November 898 399 36 462 14 566 21 795 December 1 299 665 52 747 21 073 31 530 January 1 971 828 80 028 31 971 47 837 February 2 547 116 103 376 41 299 61 793 March 2 367 134 96 071 38 380 57 427 April 1 363 969 55 357 22 115 33 090 May 834 012 33 849 13 523 20 233 June 616 590 25 025 9 997 14 959 July 513 755 20 851 8 330 12 464 August 437 027 17 737 7 086 10 602 September 373 983 15 178 6 064 9 073 Annual 13 760 991 558 496 223 118 333 843
6.3 Flood Flow Analysis
The 50-year and 100-year flood peaks were calculated for the Wilge River and the three tributaries. The Wilge River flood peaks were calculated where it leaves the mining rights area. The flood peaks for the Eastern and Western tributaries were calculated at their confluence with the Wilge River. The flood peak for the Northern tributary was calculated where is passes the open cast pit. The results are presented in Table 6.
Table 6: Peak flows in the Wilge River and the three tributaries Recurrence Wilge River Western Eastern Northern Interval Tributary Tributary Tributary 50-year 458 m 3/s 75 m 3/s 43 m 3/s 52 m 3/s 100-year 621 m 3/s 100 m 3/s 58 m 3/s 69 m 3/s
Member: B Randell BSc Eng (Civil), PhD, PrEng. www.ilandawater.co.za
March 2019 11 0122-Rep-001 Rev4
7 FLOODLINES
7.1 Backwater analysis
The backwater analysis was performed using HEC-RAS. Cross sections for the Eastern and Western tributaries were taken from 1 m contour data supplied by the client. No floodlines were done on the Wilge River as the infrastructure is located sufficiently far away from the Wilge River.
Both tributaries are small with defined channels in most areas. Some areas have incised channels. The tributaries are generally free of trees and woody vegetation. The channels mostly consist of grasses, sedges and reed beds. The banks are well vegetated, mainly with grasses. A Manning’s n of 0.035 was used outside and within the overbank stations.
No floodlines were required on the Northern tributary as the 100 m buffer is more conservative than the flood levels.
The flood peaks presented in Table 6 were used to calculate the floodlines. The 50-year and 100-year floodlines are shown in Figure 6 and Figure 7. The accuracy of the survey data cannot be verified. It is assumed that the survey data provided is a true reflection of the topography within the study area. The accuracy of the floodlines is dependent on the accuracy of the survey data.
Figure 6: Floodlines on Eastern Tributary
Member: B Randell BSc Eng (Civil), PhD, PrEng. www.ilandawater.co.za
March 2019 12 0122-Rep-001 Rev4
Figure 7: Floodlines on Western Tributary
8 BUFFER ZONES
Section 4a of Government Notice 704 (GN 704) of the South African National Water Act states the following: “ No person in control of a mine or activity may locate or place any residue deposit, dam, reservoir, together with any associated structure or any other facility within the 1:100 year flood-line or within a horizontal distance of 100 metres from any watercourse…”.
Section 4b of Government Notice 704 of the South African National Water Act states the following: “ No person in control of a mine or activity may … carry on any underground or opencast mining, prospecting or any other operation or activity under or within the 1:50 year flood-line or within a horizontal distance of 100 metres from any watercourse…”
Pollution control dams are required as part of the project so Section 4a of GN 704 will apply to these. The surface water buffer zone therefore is the greater of the 100-year floodline or 100 m from the water course. The buffer zones for the Eastern and Western tributaries are shown in Figure 8.
A conservative assessment of the flows and flow depth in the Northern tributary shows that GN 704 100 m buffer is more conservative than the 1:100 year flood level. The applicable buffer on the Northern tributary should be the 100 m distance from the water course. All infrastructure is located outside the 100 m buffer from the Wilge River as well as outside of where the 100-year floodline would be.
Member: B Randell BSc Eng (Civil), PhD, PrEng. www.ilandawater.co.za
March 2019 13 0122-Rep-001 Rev4
Figure 8: Surface water buffer zones for the Western and Eastern tributaries
9 WATER QUALITY
Baseline water quality samples at seven locations were taken on site by Geovicon in July 2014. These samples were analysed by Regen Waters, an accredited laboratory.
9.1 Surface Water Users
The water quality data was compared against the South African water quality guidelines (Department of Water Affairs and Forestry, 1996). In selecting which guidelines to compare the data against, the likely downstream users need to be considered.
The three tributaries are tributaries of the Wilge River, which is a tributary of the Olifants River. The flow in the three tributaries is small in comparison to the flow in the Wilge River. Water quality of the Olifants River is likely to dominate the water quality once the Wilge River
Member: B Randell BSc Eng (Civil), PhD, PrEng. www.ilandawater.co.za
March 2019 14 0122-Rep-001 Rev4
and the Olifants River converge. The downstream users were therefore considered in the Wilge River. The Premiermyndam is located on the Wilge River, downstream of the colliery and upstream of the confluence with the Olifants River. The downstream usage classes are evaluated below:
• Domestic users – limited drinking water, but farm labourers and local inhabitants may consume this river water and use it for laundry and cleaning. • Recreational users – it is likely that farm labourers and local inhabitants will swim in the Wilge River and the Premiermyndam and will use the water for washing. • Industrial users – there are no water quality sensitive industrial users on the Wilge River downstream of the mining rights area. • Aquatic users – the catchments are impacted by agriculture and mining and sensitive aquatic users are unlikely to be present. • Irrigation users – the river water is likely to be used for irrigation. • Livestock watering – the river water is likely to be used for livestock watering.
The water quality guidelines considered are therefore the Domestic, Irrigation, Livestock watering and Recreational water quality guidelines. The water quality at the sampling points was compared to these guidelines.
9.2 Sample Locations
Two samples are taken on the Wilge River - upstream and downstream of the mining activities. Two samples are taken on the Western tributary within the mining rights area. Two samples are taken on the Eastern tributary upstream and downstream of the existing works. One sample is taken on the Northern tributary, to the north of the mining rights area. A sample is also taken in the PCD. The upstream samples provide an indication of baseline water quality upstream of the colliery and current land use. The downstream samples provide an indication of the effects of the current land use and must be used in the future to determine the impacts of the colliery. The sample locations are shown in Figure 9.
Member: B Randell BSc Eng (Civil), PhD, PrEng. www.ilandawater.co.za
March 2019 15 0122-Rep-001 Rev4
Figure 9: Water sampling locations (groundwater points are excluded from this study)
9.3 Baseline Water Quality Analysis
Monthly water quality data was made available for analysis for each of the sample locations. Up to 18 months’ data was analysed where available. The findings are discussed below and summarised in Table 7 to Table 14.
9.3.1 Northern Tributary
The Northern tributary shows some mining-related impacts, particularly in 2019. However, other impacts that are not common to agriculture or mining are also present. The suspended solids are very high at the beginning of 2019. This could mean that the river flows were very low and pollutants were being concentrated up, with high suspended solids caused by cattle drinking. The pH is generally neutral throughout so it is unlikely that disturbed sediments have released metals into the water. However, elevated manganese could be explained by disturbed sediments.
9.3.2 Western Tributary
The Western Tributary shows a significant reduction in pH from upstream to downstream. This is consistent with coal mining related pollution. Elevated sulphates support this theory. However, TDS and EC improve from upstream to downstream which are not consistent with mining-related impacts. The sulphate impacts are not large though. This ambiguity in the results indicates unclear evidence of mining-related impacts. Further sampling is recommended to remove this ambiguity and determine if there are any surface water impacts caused by the mining activities.
Member: B Randell BSc Eng (Civil), PhD, PrEng. www.ilandawater.co.za
March 2019 16 0122-Rep-001 Rev4
9.3.3 Eastern Tributary
There is clear evidence of significant mining-related impacts on the Eastern Tributary. The salinity impacts are more acute in the wet season. This indicated poor storm water management. pH impacts are more acute in the dry season, indicated shallow seepage impacts.
9.3.4 Wilge River
The Wilge River shows indications of mining related impacts between the upstream (WS1) and downstream (WS2) sample locations. The impacts are small but are definitive. The majority of the impacts are likely to come from the Eastern Tributary.
PCD
The water quality in the PCD is poor and consistent with coal mining activities. This water must be in a properly designed lined facility.
Member: B Randell BSc Eng (Civil), PhD, PrEng. www.ilandawater.co.za
March 2019 17 0122-Rep-001 Rev4
Table 7: Summary of water quality analysis (WS-01)
WS-01 DWWWWWWWDDDDDWWWWW 7 7 8 8 8 8 8 8 8 9 1 1 1 1 1 1 1 1 1 1 9/ 1/ 1/ 2/ 3/18 4/ 6/ 8/ 0/ 2/ 2/ /0 /1 /0 0 /0 0 /05/18 /0 /07/18 /0 /1 /1 /0 Parameter 19 17/10/17 14 12/12/17 22 13/ 20 17/ 17 19 17 23 26/09/18 17 15/11/18 10 23/01/19 21 Comments
Total Dissolved Solids 202 216 246 262 208 246 238 212 218 196 210 200 236 224 276 204 The water quality exceeds the Irrigation guideline value of (260mg/l) on 12/12/2017,15/11/2018. Suspended Solids 202.0 334.0 The water quality exceeds the Irrigation guideline value of (50mg/l) on 23/01/2019,21/02/2019. Nitrate & Nitrite as N 0.10 0.10 0.14 0.10 0.10 0.10 0.10 Chlorides as Cl 18.70 27.9 27.50 18.60 13.50 15.40 17.00 15.20 15.70 20.00 20.10 18.60 21.60 22.40 22.80 15.70 16.30 16.60 Total Alkalinity as CaCO3 124 152 110 119 145 Fluoride as F 0.32 0.38 0.44 0.37 0.33 0.39 0.46 0.29 0.30 0.28 0.28 0.28 0.36 0.39 0.41 0.61 0.49 0.53 Sulphate as SO4 29.00 20.4 23.50 83.60 33.70 42.30 33.30 44.30 38.90 38.70 39.50 38.40 33.70 22.20 20.90 31.30 38.50 117.00 The water quality exceeds the Domestic guideline value - Class O (100mgCaCO3/l) on Total Hardness as CaCO3 108 128 139 132 125 141 136 115 105 199 19/09/2017,17/10/2017,14/11/2017,12/12/2017,22/01/2018,20/03/2018,26/09/2018,10/12/2018,23/01/2019,21/02/2019. Calcium as Ca 20 23 25 23 24 27 26 22 22 22 22 21 28 26 28 22 20 98 The water quality exceeds the Domestic guideline value - Class I (80mg/l) on 21/02/2019. Magnesium as Mg 14 17 19 18 16 19 19 16 15 15 15 14 16 18 19 15 13 39 Sodium as Na 26.6 28.1 31.3 25.0 21.8 26.1 28.7 21.1 22.6 26.0 25.3 21.8 25.1 29.1 36.9 25.3 24.6 28.7 Potassium as K 3.07 5.6 4.96 6.00 4.30 4.75 4.59 4.92 4.76 5.12 4.19 3.27 4.01 4.59 4.47 8.11 7.09 7.96
Iron as Fe 0.02 0.1 0.03 1.32 0.03 2.12 0.01 0.07 0.12 0.15 0.07 0.08 0.09 0.09 0.01 0.25 0.49 0.06 The water quality exceeds the Domestic guideline value - Class I (1mg/l) on 12/12/2017,13/02/2018.
Manganese as Mn 0.01 0.01 0.01 0.01 0.01 0.02 0.01 0.01 0.01 0.01 0.06 0.05 0.01 0.01 0.01 0.01 0.01 0.01 The water quality exceeds the Irrigation guideline value of (0.02mg/l) on 17/07/2018,23/08/2018. Conductivity at 25° C in mS/m 32.80 35.40 38.10 39.10 32.00 41.10 42.60 34.30 34.10 35.60 35.10 36.20 40.10 36.90 43.70 32.70 29.70 51.50 The water quality exceeds the Irrigation guideline value of (40mS/m) on 13/02/2018,20/03/2018,26/09/2018,15/11/2018,21/02/2019. pH-Value at 25 ° C 7.3 7.93 7.6 7.5 6.6 7.7 7.0 7.5 6.9 7.7 7.6 8.1 7.9 6.6 8.2 7.8 7.6 7.8
Aluminium as Al 0.0 0.0 0.0 2.4 0.0 0.0 0.0 0.0 0.1 0.0 0.0 0.0 0.0 0.0 0.0 0.3 0.7 0.0 The water quality exceeds the Domestic guideline value - Class O (0.15mg/l) on 10/12/2018, Class I (0.5mg/l) on 12/12/2017,23/01/2019. LEGEND RECREATION WATER GUIDELINE EXCEEDANCES Value DOMESTIC WATER GUIDELINE EXCEEDANCES Class O Class I Class II Class III IRRIGATION WATER GUIDELINE EXCEEDANCES Value LIVESTOCK WATER GUIDELINE EXCEEDANCES Value
Member: B Randell BSc Eng (Civil), PhD, PrEng. www.ilandawater.co.za
March 2019 18 0122-Rep-001 Rev4
Table 8: Summary of water quality analysis (WS-02) WS-02 DWWWWWWWDDDDDWWWWW 17 18 18 18 18 18 18 18 19 1/ 1/ 2/ 4/ 5/ 7/ 0/ 2/ 1/ /10/17 /1 /0 /0 /0 0 /0 /09/18 /1 /1 /0 Parameter 19/09/17 17 14 12/12/17 22 13 20/03/18 17 17/ 19/06/18 17 23/08/18 26 17 15/11/18 10 23 21/02/19 Comments
Total Dissolved Solids 276 316 242 260 252 228 230 244 288 270 264 260 284 294 The water quality exceeds the Irrigation guideline value of (260mg/l) on 19/09/2017,17/10/2017,17/05/2018,19/06/2018,17/07/2018,26/09/2018,17/10/2018. Suspended Solids 7.2 13.2 14.8 17.2 Nitrate & Nitrite as N 0.10 0.25 0.13 0.10 0.10 0.10 0.10 0.10 0.10 Chlorides as Cl 18.90 22.4 21.00 18.40 13.30 15.60 15.10 15.00 16.30 18.40 20.30 20.90 22.70 25.10 27.20 21.80 17.60 20.70 Total Alkalinity as CaCO3 155 149 130 141 186 153 175 150 Fluoride as F 0.38 0.86 0.47 0.34 0.38 0.41 0.44 0.29 0.34 0.30 0.33 0.34 0.42 0.46 0.45 0.53 0.54 0.63 The water quality exceeds the Domestic guideline value - Class O (0.7mg/l) on 17/10/2017. Sulphate as SO4 58.90 67.0 29.50 75.50 44.40 34.20 28.10 81.40 54.70 65.20 63.90 53.30 50.70 42.00 34.10 43.70 36.90 65.70 Total Hardness as CaCO3 155 174 136 131 143 141 161 The water quality exceeds the Domestic guideline value - Class O (100mgCaCO3/l) on 19/09/2017,17/10/2017,14/11/2017,12/12/2017,22/01/2018,20/03/2018,26/09/2018. Calcium as Ca 31 35 26 23 28 25 27 26 30 29 31 32 31 33 29 32 30 2 8 The water quality exceeds the Domestic guideline value - Class O (32mg/l) on 17/10/2017,17/10/2018. Magnesium as Mg 19 21 17 18 18 17 18 18 20 20 19 19 21 21 19 21 18 20 Sodium as Na 33.8 37.3 31.6 23.7 25.8 24.0 27.6 22.8 28.9 31.4 30.3 31.6 32.8 35.7 35.9 36.9 27.9 32.2 Potassium as K 2.96 3.2 3.20 5.50 4.09 4.16 3.71 4.37 3.71 4.31 3.55 3.22 3.14 3.31 3.79 6.22 7.22 8.57
Iron as Fe 0.01 0.0 0.07 0.62 0.06 0.16 0.70 0.25 0.09 0.09 0.05 0.05 0.21 0.19 0.11 0.12 0.05 0.09 The water quality exceeds the Domestic guideline value - Class O (0.5mg/l) on 12/12/2017,20/03/2018. Manganese as Mn 0.01 0.01 0.01 0.01 0.02 0.01 0.02 0.01 0.01 0.02 0.01 0.01 0.01 0.02 0.01 0.01 0.01 0.02 The water quality exceeds the Irrigation guideline value of (40mS/m) on Conductivity at 25° C in mS/m 44.00 48.00 37.20 37.30 37.40 38.70 39.10 38.90 39.40 43.50 43.60 44.00 46.60 45.00 45.90 42.40 39.00 43.80 19/09/2017,17/10/2017,19/06/2018,17/07/2018,23/08/2018,26/09/2018,17/10/2018,15/11/2018,10/12/2018,21/02/2019. pH-Value at 25 ° C 7.6 8.18 7.7 7.3 6.9 7.9 7.4 7.7 7.1 7.9 8.3 8.3 8.3 7.7 8.1 8.2 8.1 7.9 Boron as B 0.0 0.0 0.0 0.0 Ammonia as N 0.20 Phosphate as PO4 0.10 0.10 0.10 0.01
Aluminium as Al 0.02 0.01 0.01 1.07 0.02 0.01 0.10 0.19 0.07 0.07 0.03 0.01 0.05 0.05 0.01 0.04 0.02 0.06 The water quality exceeds the Domestic guideline value - Class O (0.15mg/l) on 17/04/2018, Class I (0.5mg/l) on 12/12/2017. LEGEND RECREATION WATER GUIDELINE EXCEEDANCES Value DOMESTIC WATER GUIDELINE EXCEEDANCES Class O Class I Class II Class III IRRIGATION WATER GUIDELINE EXCEEDANCES Value LIVESTOCK WATER GUIDELINE EXCEEDANCES Value
Member: B Randell BSc Eng (Civil), PhD, PrEng. www.ilandawater.co.za
March 2019 19 0122-Rep-001 Rev4
Table 9: Summary of water quality analysis (WDS1) WDS1 WWWWW 18 18 19 / 1/18 / / 10 12 02 Parameter / 5/1 / / Comments 17 1 10 23/01/19 21 Total Dissolved Solids 216 Dry Dry 178
Suspended Solids 136.0 44.4 The water quality exceeds the Irrigation guideline value of (50mg/l) on 23/01/2019.
Nitrate & Nitrite as N 0.10 0.10 Chlorides as Cl 36.30 23.70 42.00
Total Alkalinity as CaCO3 17 Fluoride as F 0.25 0.21 0.20
Sulphate as SO4 32.20 58.00 55.30 Total Hardness as CaCO3 42 56
Calcium as Ca 23 8 12 Magnesium as Mg 16 5 7
Sodium as Na 24.9 24.6 40.4 Potassium as K 5.12 0.71 2.44
Iron as Fe 0.07 0.71 0.12 The water quality exceeds the Domestic guideline value - Class O (0.5mg/l) on 23/01/2019. The water quality exceeds the Domestic guideline value - Class O (0.1mg/l) on 23/01/2019. The water quality exceeds the Irrigation guideline value of (0.02mg/l) on Manganese as Mn 0.01 0.12 0.07 23/01/2019,21/02/2019.
Conductivity at 25° C in mS/m 32.90 20.70 26.20 The water quality exceeds the Recreation guideline value of (5) on 23/01/2019,21/02/2019. The water quality exceeds the Domestic guideline value - Class O (70) on pH-Value at 25 ° C 7.6 4.9 5.3 23/01/2019,21/02/2019. The water quality exceeds the Irrigation guideline value of (40) on 23/01/2019,21/02/2019. Aluminium as Al 0.0 0.2 0.1 LEGEND RECREATION WATER GUIDELINE EXCEEDANCES Value DOMESTIC WATER GUIDELINE EXCEEDANCES Class O Class I Class II Class III IRRIGATION WATER GUIDELINE EXCEEDANCES Value LIVESTOCK WATER GUIDELINE EXCEEDANCES Value
Member: B Randell BSc Eng (Civil), PhD, PrEng. www.ilandawater.co.za
March 2019 20 0122-Rep-001 Rev4
Table 10: Summary of water quality analysis (WDS2) WDS2 WWWWW 8 8 /1 /1 /18 10 02/19 7/ 5/11 Parameter 1 1 10/12 23/01/19 21/ Comments The water quality exceeds the Domestic guideline value - Class O (450mg/l) on 10/12/2018,21/02/2019. The water quality exceeds the Irrigation guideline value of (260mg/l) on Total Dissolved Solids 378 342 502 620 17/10/2018,15/11/2018,10/12/2018,21/02/2019.
Suspended Solids 1040.0 206.0 The water quality exceeds the Irrigation guideline value of (50mg/l) on 23/01/2019,21/02/2019.
Nitrate & Nitrite as N 0.10 0.17 Chlorides as Cl 31.40 18.7 29.60 36.70 24.20
Total Alkalinity as CaCO3 303
Fluoride as F 0.52 0.49 0.68 0.31 0.79 The water quality exceeds the Domestic guideline value - Class O (0.7mg/l) on 21/02/2019.
Sulphate as SO4 58.30 3.4 106.00 516.00 188.00 The water quality exceeds the Domestic guideline value - Class I (400mg/l) on 23/01/2019.
Total Hardness as CaCO3 364 598 299 The water quality exceeds the Domestic guideline value - Class I (200mgCaCO3/l) on 21/02/2019, Class II (300mgCaCO3/l) on 10/12/2018,23/01/2019.
Calcium as Ca 34 34 64 127 51 The water quality exceeds the Domestic guideline value - Class O (32mg/l) on 17/10/2018,15/11/2018,10/12/2018,21/02/2019, Class I (80mg/l) on 23/01/2019. Magnesium as Mg 32 33 49 68 42
Sodium as Na 41.0 23.5 31.3 57.1 75.5 The water quality exceeds the Irrigation guideline value of (70mg/l) on 21/02/2019. Potassium as K 3.88 3.1 6.18 10.80 4.87 The water quality exceeds the Domestic guideline value - Class I (1mg/l) on 17/10/2018, Class II (5mg/l) on 10/12/2018,21/02/2019, Class III (10mg/l) on 15/11/2018,23/01/2019. The Iron as Fe 3.77 10.1 9.81 32.30 9.41 water quality exceeds the Irrigation guideline value of (5mg/l) on 15/11/2018,10/12/2018,23/01/2019,21/02/2019. The water quality exceeds the Livestock guideline value of The water quality exceeds the Domestic guideline value - Class I (0.4mg/l) on 17/10/2018,15/11/2018,21/02/2019, Class II (4mg/l) on 10/12/2018, Class III (10mg/l) on 23/01/2019. Manganese as Mn 1.60 3.93 6.59 11.40 1.00 The water quality exceeds the Irrigation guideline value of (0.02mg/l) on 17/10/2018,15/11/2018,10/12/2018,23/01/2019,21/02/2019. The water quality exceeds the Livestock The water quality exceeds the Domestic guideline value - Class O (70mS/m) on 23/01/2019,21/02/2019. The water quality exceeds the Irrigation guideline value of (40mS/m) on Conductivity at 25° C in mS/m 52.90 55.40 68.40 107.00 87.50 17/10/2018,15/11/2018,10/12/2018,23/01/2019,21/02/2019. pH-Value at 25 ° C 7.9 7.33 7.9 7.3 7.4
Aluminium as Al 2.2 0.0 0.9 2.7 2.5 The water quality exceeds the Domestic guideline value - Class I (0.5mg/l) on 17/10/2018,10/12/2018,23/01/2019,21/02/2019. LEGEND RECREATION WATER GUIDELINE EXCEEDANCES Value DOMESTIC WATER GUIDELINE EXCEEDANCES Class O Class I Class II Class III IRRIGATION WATER GUIDELINE EXCEEDANCES Value LIVESTOCK WATER GUIDELINE EXCEEDANCES Value
Member: B Randell BSc Eng (Civil), PhD, PrEng. www.ilandawater.co.za
March 2019 21 0122-Rep-001 Rev4
Table 11: Summary of water quality analysis (SWMS)
SWMS DWWWWWWWDDDDDWWWWW 7 7 7 7 8 8 8 8 8 8 /1 /1 /1 /1 /1 /1 /1 /1 9 0 1 2 1 2 3 4 /0 /1 /1 /1 /0 /0 Parameter 19 17 14 12 22 13 20/0 17/0 17/05/1 19/06/1 17/07/18 23/08/18 26/09/18 17/10/18 15/11/18 10/12/18 23/01/19 21/02/19 Comments The water quality exceeds the Domestic guideline value - Class O (450mg/l) on 17/10/2017,22/01/2018,13/02/2018,20/03/2018,17/04/2018,17/05/2018,19/06/2018,26/09/2018. Total Dissolved Solids 420 766 128 234 636 962 998 770 766 570 360 390 628 442 The water quality exceeds the Irrigation guideline value of (260mg/l) on Suspended Solids 4.8 40.4 74.0 35.2 The water quality exceeds the Irrigation guideline value of (50mg/l) on 23/01/2019. Nitrate & Nitrite as N 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 Chlorides as Cl 12.20 14.4 15.10 8.65 9.34 9.08 10.80 10.10 10.70 11.10 9.23 10.30 13.70 10.60 17.60 21.20 29.30 23.70 Total Alkalinity as CaCO3 28 67 24 16 49 46 102 32 Fluoride as F 0.20 0.25 0.51 0.20 0.20 0.20 0.37 0.29 0.21 0.20 0.20 0.20 0.20 0.20 0.33 0.42 0.61 0.51 The water quality exceeds the Domestic guideline value - Class O (200mg/l) on 19/09/2017,22/01/2018,19/06/2018,17/07/2018,23/08/2018,17/10/2018, Class I (400mg/l) on Sulphate as SO4 264.00 470.0 16.40 149.00 391.00 723.00 667.00 500.00 473.00 375.00 228.00 253.00 422.00 276.00 706.00 806.00 1026.00 833.00 17/10/2017,17/04/2018,17/05/2018,26/09/2018, Class II (600mg/l) on 13/02/2018,20/03/2018,15/11/2018,10/12/2018,21/02/2019, Class III (1000mg/l) on 23/01/2019. The water The water quality exceeds the Domestic guideline value - Class O (100mgCaCO3/l) on 12/12/2017, Class I (200mgCaCO3/l) on 19/09/2017, Class II (300mgCaCO3/l) on Total Hardness as CaCO3 260 569 52 132 424 714 402 17/10/2017,22/01/2018,26/09/2018, Class III (600mgCaCO3/l) on 20/03/2018. The water quality exceeds the Domestic guideline value - Class O (32mg/l) on Calcium as Ca 40 86 10 21 66 110 108 79 77 65 36 38 65 46 113 142 186 135 19/09/2017,22/01/2018,17/04/2018,17/05/2018,19/06/2018,17/07/2018,23/08/2018,26/09/2018,17/10/2018, Class I (80mg/l) on The water quality exceeds the Domestic guideline value - Class O (70mg/l) on 17/10/2017,17/04/2018,17/05/2018, Class I (100mg/l) on Magnesium as Mg 39 86 7 19 63 109 108 77 72 64 34 33 58 41 102 140 174 123 13/02/2018,20/03/2018,15/11/2018,10/12/2018,23/01/2019,21/02/2019. Sodium as Na 17.3 22.6 21.6 13.7 17.2 23.7 21.2 18.0 19.3 21.1 15.0 16.3 18.4 14.7 25.4 31.6 44.6 32.2 Potassium as K 2.42 2.9 3.85 2.28 2.16 1.10 3.36 2.32 2.97 3.15 0.95 2.50 2.30 1.06 2.91 4.21 6.71 5.64 Iron as Fe 0.23 0.0 0.01 0.01 0.06 0.39 0.20 0.02 0.03 0.03 0.02 0.70 0.22 0.09 0.09 0.14 0.03 0.09 The water quality exceeds the Domestic guideline value - Class O (0.5mg/l) on 23/08/2018. The water quality exceeds the Domestic guideline value - Class O (0.1mg/l) on 19/09/2017,13/02/2018,20/03/2018,17/07/2018,10/12/2018,23/01/2019, Class I (0.4mg/l) on Manganese as Mn 0.20 0.01 0.01 0.03 0.01 0.26 0.14 0.01 0.03 0.01 0.11 0.06 0.05 0.77 0.02 0.16 0.16 0.03 17/10/2018. The water quality exceeds the Irrigation guideline value of (0.02mg/l) on The water quality exceeds the Domestic guideline value - Class O (70mS/m) on Conductivity at 25° C in mS/m 58.10 101.00 19.60 36.90 81.20 125.00 113.00 99.00 94.10 79.30 51.70 53.40 88.60 57.20 133.00 151.00 183.00 149.00 17/10/2017,22/01/2018,13/02/2018,20/03/2018,17/04/2018,17/05/2018,19/06/2018,26/09/2018,15/11/2018,21/02/2019, Class I (150mS/m) on 10/12/2018,23/01/2019. The The water quality exceeds the Recreation guideline value of (0) on 12/12/2017,13/02/2018,17/05/2018,17/07/2018,23/08/2018,26/09/2018. The water quality exceeds the Domestic pH-Value at 25 ° C 6.6 7.61 7.3 6.0 6.9 6.0 6.7 6.9 6.4 6.7 5.9 6.3 6.2 7.4 8.0 7.6 7.6 8.2 guideline value - Class O (70) on 13/02/2018,17/07/2018. The water quality exceeds the Irrigation guideline value of (40) on Boron as B 0.0 0.0 0.0 0.0 Ammonia as N 0.20 Phosphate as PO4 0.10 0.10 0.10 0.10 Aluminium as Al 0.05 0.02 0.03 0.08 0.02 0.03 0.02 0.03 0.04 0.05 0.01 0.02 0.03 0.02 0.03 0.04 0.02 0.05 LEGEND RECREATION WATER GUIDELINE EXCEEDANCES Value DOMESTIC WATER GUIDELINE EXCEEDANCES Class O Class I Class II Class III IRRIGATION WATER GUIDELINE EXCEEDANCES Value LIVESTOCK WATER GUIDELINE EXCEEDANCES Value
Member: B Randell BSc Eng (Civil), PhD, PrEng. www.ilandawater.co.za
March 2019 22 0122-Rep-001 Rev4
Table 12: Summary of water quality analysis (SWUS)
SWUS DWWWWWWWDDDDDWWWWW
7 7 18 18 18 8 8 8 8 8 9 9 /1 /1 /1 /1 /1 /1 /1 /1 /1 9 0 4/18 5/ 6/ 7/ 8 9 0 1 2 1 2 /0 0 0 0 0 /0 /0 /1 /1 /1 /0 /0 Parameter 19 17/1 14/11/17 12/12/17 22/01/18 13/02/18 20/03/18 17/ 17/ 19/ 17/ 23 26 17 15 10 23 21 Comments
Total Dissolved Solids 108 104 940 114 94 96 104 96 102 94 108 114 144 132 The water quality exceeds the Domestic guideline value - Class O (450mg/l) on 14/11/2017. The water quality exceeds the Irrigation guideline value of (260mg/l) on 14/11/2017. Suspended Solids 28.4 34.0 123.0 254.0 The water quality exceeds the Irrigation guideline value of (50mg/l) on 23/01/2019,21/02/2019. Nitrate & Nitrite as N 0.10 0.10 0.14 0.11 0.10 0.10 0.10 0.10 0.10 Chlorides as Cl 13.90 15.1 15.00 12.00 9.30 10.80 10.60 11.50 11.90 14.40 16.80 17.50 21.60 22.00 22.40 24.00 27.50 25.20 Total Alkalinity as CaCO3 53 43 38 43 68 69 94 63
Fluoride as F 0.40 0.48 0.27 0.50 0.41 0.44 0.44 0.37 0.33 0.28 0.30 0.30 0.41 0.46 0.56 0.60 0.75 0.65 The water quality exceeds the Domestic guideline value - Class O (0.7mg/l) on 23/01/2019.
Sulphate as SO4 16.50 16.5 636.00 18.10 16.30 15.40 15.40 14.90 15.70 20.50 23.60 26.30 28.50 27.30 28.50 33.50 39.40 51.90 The water quality exceeds the Domestic guideline value - Class II (600mg/l) on 14/11/2017.
Total Hardness as CaCO3 40 49 633 50 42 49 42 The water quality exceeds the Domestic guideline value - Class III (600mgCaCO3/l) on 14/11/2017. Calcium as Ca 8 10 94 11 8 9 10 8 6 5 6 7 8 9 10 12 13 12 The water quality exceeds the Domestic guideline value - Class I (80mg/l) on 14/11/2017. Magnesium as Mg 5 6 97 6 5 6 6 5 4 4 4 5 5 6 6 8 9 8 The water quality exceeds the Domestic guideline value - Class O (70mg/l) on 14/11/2017. Sodium as Na 18.7 21.9 22.7 20.2 15.0 16.7 17.4 15.5 17.0 18.6 20.5 20.8 22.5 26.2 26.2 30.3 37.1 32.8 Potassium as K 4.12 3.8 3.04 3.03 2.08 2.27 2.03 2.06 2.09 2.87 2.62 2.89 3.54 3.19 3.41 4.28 4.37 4.00 The water quality exceeds the Domestic guideline value - Class O (0.5mg/l) on 12/12/2017,13/02/2018,19/06/2018,17/07/2018,17/10/2018, Class I (1mg/l) on Iron as Fe 3.50 0.1 0.04 0.56 0.05 0.74 0.11 0.04 0.50 0.79 0.86 1.05 2.03 0.90 0.26 0.24 0.31 0.49 19/09/2017,23/08/2018,26/09/2018. The water quality exceeds the Domestic guideline value - Class O (0.1mg/l) on 10/12/2018. The water quality exceeds the Irrigation guideline value of (0.02mg/l) on Manganese as Mn 0.02 0.02 0.01 0.10 0.01 0.01 0.02 0.01 0.01 0.06 0.01 0.01 0.10 0.01 0.01 0.11 0.01 0.01 12/12/2017,19/06/2018,26/09/2018,10/12/2018.
Conductivity at 25° C in mS/m 17.30 19.90 110.00 17.40 14.40 14.80 17.40 14.90 15.50 16.00 18.10 20.00 21.90 20.20 23.90 27.20 30.00 29.00 The water quality exceeds the Domestic guideline value - Class O (70mS/m) on 14/11/2017. The water quality exceeds the Irrigation guideline value of (40mS/m) on 14/11/2017. The water quality exceeds the Recreation guideline value of (5) on 12/12/2017,22/01/2018. The water quality exceeds the Domestic guideline value - Class O (70) on 22/01/2018, Class pH-Value at 25 ° C 7.0 7.27 7.4 4.5 6.0 7.6 7.2 7.2 7.1 7.3 7.6 7.7 6.7 7.3 7.6 7.7 7.7 7.3 I (70) on 12/12/2017. The water quality exceeds the Irrigation guideline value of (40) on 12/12/2017,22/01/2018. Boron as B 0.0 0.0 0.0 0.0 Ammonia as N 0.20 Phosphate as PO4 0.10 0.10 0.10 0.10 The water quality exceeds the Domestic guideline value - Class O (0.15mg/l) on 12/12/2017,19/06/2018,23/01/2019, Class I (0.5mg/l) on Aluminium as Al 0.87 0.07 0.01 0.24 0.02 0.10 0.06 0.03 0.76 0.44 1.55 0.92 3.10 1.19 0.10 0.10 0.21 0.64 19/09/2017,17/05/2018,17/07/2018,23/08/2018,26/09/2018,17/10/2018,21/02/2019. LEGEND RECREATION WATER GUIDELINE EXCEEDANCES Value DOMESTIC WATER GUIDELINE EXCEEDANCES Class O Class I Class II Class III IRRIGATION WATER GUIDELINE EXCEEDANCES Value LIVESTOCK WATER GUIDELINE EXCEEDANCES Value
Member: B Randell BSc Eng (Civil), PhD, PrEng. www.ilandawater.co.za
March 2019 23 0122-Rep-001 Rev4
Table 13: Summary of water quality analysis (WUS) WUS WWWWW 8 9 /18 /18 1 1 0 1 2/19 1 /1 /12/ 0 Parameter 17/ 15 10 23/01/ 21/ Comments
Total Dissolved Solids 244 258 240 240
Suspended Solids 270.0 68.8 The water quality exceeds the Irrigation guideline value of (50mg/l) on 23/01/2019,21/02/2019. Nitrate & Nitrite as N 0.11 0.15 Chlorides as Cl 13.50 9.9 8.64 15.10 13.50 Total Alkalinity as CaCO3 182 Fluoride as F 0.27 0.26 0.28 0.41 0.29 Sulphate as SO4 18.90 13.7 9.22 15.30 15.50
Total Hardness as CaCO3 181 187 157 The water quality exceeds the Domestic guideline value - Class O (100mgCaCO3/l) on 10/12/2018,23/01/2019,21/02/2019. Calcium as Ca 34 35 35 35 30 The water quality exceeds the Domestic guideline value - Class O (32mg/l) on 17/10/2018,15/11/2018,10/12/2018,23/01/2019. Magnesium as Mg 21 20 23 24 20 Sodium as Na 21.9 20.2 20.8 26.7 21.7 Potassium as K 2.19 1.3 2.02 2.50 2.24 Iron as Fe 0.09 0.2 0.18 0.20 0.18
Manganese as Mn 0.04 0.01 0.01 0.07 0.01 The water quality exceeds the Irrigation guideline value of (0.02mg/l) on 17/10/2018,23/01/2019.
Conductivity at 25° C in mS/m 37.10 40.80 37.40 41.90 38.30 The water quality exceeds the Irrigation guideline value of (40mS/m) on 15/11/2018,23/01/2019. pH-Value at 25 ° C 8.2 7.96 8.1 7.9 8.0 Aluminium as Al 0.0 0.0 0.0 0.0 0.0 LEGEND RECREATION WATER GUIDELINE EXCEEDANCES Value DOMESTIC WATER GUIDELINE EXCEEDANCES Class O Class I Class II Class III IRRIGATION WATER GUIDELINE EXCEEDANCES Value LIVESTOCK WATER GUIDELINE EXCEEDANCES Value
Member: B Randell BSc Eng (Civil), PhD, PrEng. www.ilandawater.co.za
March 2019 24 0122-Rep-001 Rev4
Table 14: Summary of water quality analysis (PCD)
PCD DWWWWWWWDDDDDWWWWW
8 8 8 /17 /17 /17 /17 /1 /18 /18 /18 /18 /1 /1 /18 /19 /19 3 0 /09 /10 /11 /02/18 /0 /04 /05 /06 /07 /09/18 /1 /11 /12 /01 /02 Parameter 19 17 14 12/12 22/01/18 18 20 17 17 19 17 23/08/18 26 17 15 10 23 21 Comments The water quality exceeds the Domestic guideline value - Class O (450mg/l) on 14/11/2017,12/12/2017, Class I (1000mg/l) on Total Dissolved Solids Dry Dry 606 680 2264 1326 1876 1598 1718 2116 2178 2918 6514 3514 Dry Dry Dry 448 22/01/2018,18/02/2018,20/03/2018,17/04/2018,17/05/2018,19/06/2018,17/07/2018, Class II (2400mg/l) on 23/08/2018, Class III (3400mg/l) on 26/09/2018,17/10/2018. The water Nitrate & Nitrite as N 0.1 0.1 0.1 0.1 Chlorides as Cl 9.70 3.42 2.45 2.90 2.60 4.96 10.00 2.60 3.26 2.83 12.70 20.50 10.80 Total Alkalinity as CaCO3 5.00 0.00 0.00 50.00 Fluoride as F 0.2 0.2 0.2 0.2 0.44 0.27 0.33 0.29 0.22 0.2 0.65 0.33 0.37 The water quality exceeds the Domestic guideline value - Class O (200mg/l) on 21/02/2019, Class I (400mg/l) on 14/11/2017,12/12/2017, Class II (600mg/l) on 18/02/2018, Class III Sulphate as SO4 427.00 474.00 1,461.00 903.00 1,267.00 1,102.00 1,219.00 1,439.00 1,514.00 2,030.00 4,534.00 2,376.00 270.00 (1000mg/l) on 22/01/2018,20/03/2018,17/04/2018,17/05/2018,19/06/2018,17/07/2018,23/08/2018,26/09/2018,17/10/2018. The water quality exceeds the Livestock guideline The water quality exceeds the Domestic guideline value - Class I (200mgCaCO3/l) on 21/02/2019, Class II (300mgCaCO3/l) on 14/11/2017,12/12/2017, Class III (600mgCaCO3/l) on Total Hardness as CaCO3 366.00 429.00 1558.00 1275.00 4053.00 276.00 22/01/2018,20/03/2018,26/09/2018. The water quality exceeds the Domestic guideline value - Class O (32mg/l) on 14/11/2017,21/02/2019, Class I (80mg/l) on 12/12/2017, Class II (150mg/l) on Calcium as Ca 80 83 306 186 250 196 231 309 285 369 649 424 71 18/02/2018,20/03/2018,17/04/2018,17/05/2018,17/07/2018, Class III (300mg/l) on 22/01/2018,19/06/2018,23/08/2018,26/09/2018,17/10/2018. The water quality exceeds the Domestic guideline value - Class I (100mg/l) on 22/01/2018,18/02/2018,20/03/2018,17/04/2018,17/05/2018,19/06/2018,17/07/2018, Class II Magnesium as Mg 40 54 193 116 158 129 151 183 190 237 591 307 24 (200mg/l) on 23/08/2018,17/10/2018, Class III (400mg/l) on 26/09/2018. The water quality exceeds the Livestock guideline value of (500mg/l) on 26/09/2018. Sodium as Na 8 7 13 8 5 12 16 19 17 21 48 39 8
Potassium as K 24.4 6.4 8.1 6.4 5.0 18.3 33.1 30.0 22.3 26.9 80.0 82.9 25.9 The water quality exceeds the Domestic guideline value - Class O (25mg/l) on 17/05/2018,19/06/2018,23/08/2018,21/02/2019, Class I (50mg/l) on 26/09/2018,17/10/2018. The water quality exceeds the Domestic guideline value - Class O (0.5mg/l) on 17/10/2018, Class I (1mg/l) on 17/07/2018,21/02/2019, Class III (10mg/l) on 23/08/2018,26/09/2018. Iron as Fe 0.03 0.01 0.21 0.22 0.31 0.06 0.15 0.14 1.89 19.10 21.30 0.97 1.23 The water quality exceeds the Irrigation guideline value of (5mg/l) on 23/08/2018,26/09/2018. The water quality exceeds the Livestock guideline value of (10mg/l) on The water quality exceeds the Domestic guideline value - Class I (0.4mg/l) on 21/02/2019, Class II (4mg/l) on 14/11/2017,12/12/2017, Class III (10mg/l) on Manganese as Mn 7.73 4.03 16.40 10.30 15.80 10.20 12.60 17.20 17.50 21.20 43.70 27.80 3.15 22/01/2018,18/02/2018,20/03/2018,17/04/2018,17/05/2018,19/06/2018,17/07/2018,23/08/2018,26/09/2018,17/10/2018. The water quality exceeds the Irrigation guideline value The water quality exceeds the Domestic guideline value - Class O (70mS/m) on 14/11/2017,12/12/2017, Class I (150mS/m) on Conductivity at 25° C in mS/m 77.70 85.90 216.00 162.00 171.00 178.00 191.00 229.00 245.00 285.00 565.00 310.00 65.40 22/01/2018,18/02/2018,20/03/2018,17/04/2018,17/05/2018,19/06/2018,17/07/2018,23/08/2018,17/10/2018, Class III (520mS/m) on 26/09/2018. The water quality exceeds the The water quality exceeds the Recreation guideline value of (0) on pH-Value at 25 ° C 4.71 4.74 3.76 3.77 3.83 4.49 4.71 4.27 3.86 5.68 6.10 4.04 6.53 14/11/2017,12/12/2017,22/01/2018,18/02/2018,20/03/2018,17/04/2018,17/05/2018,19/06/2018,17/07/2018,23/08/2018,26/09/2018,17/10/2018. The water quality exceeds the The water quality exceeds the Domestic guideline value - Class O (0.15mg/l) on 14/11/2017,12/12/2017,17/04/2018,23/08/2018, Class I (0.5mg/l) on Aluminium as Al 0.2 0.4 3.3 1.8 3.1 0.3 1.1 1.7 2.9 0.2 0.0 0.7 0.0 22/01/2018,18/02/2018,20/03/2018,17/05/2018,19/06/2018,17/07/2018,17/10/2018. LEGEND RECREATION WATER GUIDELINE EXCEEDANCES Value DOMESTIC WATER GUIDELINE EXCEEDANCES Class O Class I Class II Class III IRRIGATION WATER GUIDELINE EXCEEDANCES Value LIVESTOCK WATER GUIDELINE EXCEEDANCES Value
Member: B Randell BSc Eng (Civil), PhD, PrEng. www.ilandawater.co.za
March 2019 25 0122-Rep-001 Rev4
10 IMPACT ASSESSMENT
10.1 Project Description
The project involves the construction of the following infrastructure: • Dedicated ROM stockpiles to temporarily store run of mine and product • A washing, screening, and crushing plant will be constructed on mining rights area • Slurry ponds to dry the slurry before being sold • A discard dump • Topsoil and overburden stockpiles • Haul roads where coal will be transported • Contaminated storm water is assumed to be collected in dedicated pollution control dams.
10.2 Methodology for Impact Assessment
Activities on the colliery have been taken through an impact assessment prior to and post mitigation measures. The recommended mitigation measures have been included in the impact assessments. Impacts are assessed for the construction, operational and closure phases of the project. The methodology used for the impact assessments is presented below:
Occurrence • Probability of occurrence (how likely it is that the impact will occur) • Duration of occurrence (how long impacts will last)
Severity • Magnitude of impact (the severity of the impact) • Scale of impact (the extent of the impact).
Member: B Randell BSc Eng (Civil), PhD, PrEng. www.ilandawater.co.za
March 2019 26 0122-Rep-001 Rev4
The following ranking scales were used:
Probability (P) Duration (D) 5: Definite/don’t know 5: Permanent 4: Highly probable 4: Long term (ceases with the operational life) 3: Medium probability 3: Medium term (5-15 years) 2: Low probability 2: Short term (0-5 years) 1: Improbable 1: Immediate 0: None Scale (S) Magnitude (M) 5: International 10: Very high/don’t know 4: National 8: High 3: Regional (within a 100 km radius) 6: Moderate 2: Local (within a 5 km radius) 4: Low 1: Site only 2: Minor 0: None
The impact is calculated as: Impact score = (M + D + S) x P. The maximum impact score is 100. The impact ratings were based on the Impact score and are rated as follows: • High environmental impact: Impact score between 60 and 100. • Moderate environmental impact: Impact score between 30 and 59. • Low environmental impact: Impact score between 0 and 29.
10.3 Impacts During the Construction Period
A distinction needs to be made between the construction of infrastructure and the open cast mining. Both will require heavy earthmoving machinery. The impacts described in this section relate to the construction of pre-mining infrastructure around the open cast workings and the pre-deposition works on the various stockpiles. Mining and stockpiling of materials falls within the operational period. Impacts relating to the operational period are discussed in Section 10.4.
10.3.1 Impacts due to topsoil stripping
Impact assessment
During the construction phase, topsoil from all facility footprints will be stripped and stockpiled for future use. This may result in the following impacts: • Areas that have been stripped of vegetation and topsoil will be prone to erosion. This could lead to increased suspended solids being deposited into the three tributaries and the Wilge River.
Member: B Randell BSc Eng (Civil), PhD, PrEng. www.ilandawater.co.za
March 2019 27 0122-Rep-001 Rev4
• The topsoil stockpiles will be prone to erosion prior to being vegetated. Natural re- vegetation will likely take more than one season to completely cover the stockpiles. The resultant erosion could lead to increased suspended solids being deposited into the three tributaries and the Wilge River.
The affected areas will be relatively small. Erosion impacts will be short term and will cease once the facilities are constructed and the topsoil stockpile is vegetated.
Mitigation
Mitigation of the impacts should include the following: • Areas that are stripped should be optimised to limit unnecessary stripping. • Storm water from upslope of the stripped areas should be diverted around these areas to limit the amount of storm water flowing over these areas. • The timing of the topsoil stripping should be optimised to limit the time between stripping and construction/deposition. Where practical constraints exist and areas need to be left stripped for long periods, contour ploughing or ripping could reduce run-off and hence reduce erosion. • Dry season construction is preferable. • Hydro seeding of topsoil stockpiles is recommended to speed up vegetation cover. An appropriate seed mix should be designed by a vegetation specialist.
Residual impact
The residual impacts will probably be very low due to the temporary nature of the impact. Large storm flows in the Wilge River will wash the excess sediment into downstream river systems. These sediment loads are likely to be very small in relation to the sediment loads in the Wilge River. This sediment may ultimately reach the Loskop Dam.
Cumulative impact
Topsoil stripping will add to sediment loads produced by erosion from upstream agricultural activities. While it occurs, the impact will be significant compared to upstream impacts of a similar nature. The impact will be temporary and will cease shortly after construction commences and the topsoil stockpile is vegetated.
Impact rating table
Construction Impact: Topsoil stripping Prior to mitigation Probability Duration Scale Magnitude Impact score Impact 5 2 2 6 50 Moderate Post mitigation Probability Duration Scale Magnitude Impact score Impact 5 2 2 2 30 Low
Member: B Randell BSc Eng (Civil), PhD, PrEng. www.ilandawater.co.za
March 2019 28 0122-Rep-001 Rev4
10.3.2 Impacts due to construction related pollution
Impact assessment
During the construction phase, a significant number of vehicles will be driving around the site. In addition to this, fuels are stored on site and chemicals are used during normal construction activities. This may result in the following impacts: • If the construction vehicles are poorly maintained, oil spills could cause pollution if washed off roads by storm water. • Vehicle wash bays are a common source of hydrocarbon pollutants. • Leaks from fuel depots could result in surface water pollution. • Spillage and unsafe storage of chemicals could result in surface water contamination.
The affected areas will be the entire construction site. Spillage impacts will be short term and will cease after the completion of construction. If soils have become contaminated, this will leach out over a prolonged period.
Mitigation
Mitigation of the impacts should include the following: • All construction vehicles should be well maintained and inspected for hydrocarbon leaks weekly. • Wash bay discharge water should flow through an oil separator. • Fuel depots and refuelling areas should be bunded. • Chemicals should be stored in a central secure area. • Regular toolbox talks on the responsible handling of chemicals should be undertaken.
Residual impact
If limited soil contamination occurs, the residual impacts will probably be very low.
Cumulative impact
There are no known significant upstream sources of hydrocarbon pollutants, although farming activities and urban settlements in the catchment could result in hydrocarbon pollution. Hydrocarbons are currently not measured in the three tributaries and the Wilge River and it is unlikely that significant amounts of hydrocarbon pollution exist in these rivers.
Member: B Randell BSc Eng (Civil), PhD, PrEng. www.ilandawater.co.za
March 2019 29 0122-Rep-001 Rev4
Impact rating table
Construction Impact: Construction related pollution Prior to mitigation Probability Duration Scale Magnitude Impact score Impact 3 2 2 4 24 Low Post mitigation Probability Duration Scale Magnitude Impact score Impact 2 2 2 4 16 Low
10.4 Impacts During the Operational Phase
10.4.1 Impacts due to contaminated water discharge
Impact assessment
Some areas of the colliery should be considered as dirty areas. These areas typically include the product and discard stockpiles, the hards stockpiles, the slurry ponds, the open cast workings, workshops and haul roads. Storm water and seepage generated from these areas will likely be contaminated and have a detrimental effect on the water quality in the three tributaries and the Wilge River. These impacts will be most acute during the dry season when stream flows are low.
Mitigation
The colliery must have an undertaking to comply with Government Notice 704 of the South African National Water Act. This act limits discharges of contaminated water from mining related activities to less than once in 50 years on average. Contaminated water should be reused or treated to adequate discharge standards prior to release.
Should a legal discharge occur as a result of extreme rainfall conditions, the three tributaries and the Wilge River should have sufficient capacity to dilute poor quality spillage water. The impacts from extreme rainfall conditions should be low and will last for a short duration. Impacts resulting from negligence or mismanagement could be more severe. The severity of the impacts would be related to the volume and quality of water that is spilled. Impacts relating to small spillages would probably be relatively low to moderate and would be short in duration. Impacts relating to large spillages would be high. The effects would be short to medium term.
Mitigation of the impacts must include the following: • Shallow seepage and contaminated storm water run-off must be collected and routed to lined pollution control dams. The pollution control dams must be sized in accordance with Government Notice 704 of the South African National Water Act.
Member: B Randell BSc Eng (Civil), PhD, PrEng. www.ilandawater.co.za
March 2019 30 0122-Rep-001 Rev4
• Pollution control dam water levels must be constantly monitored. Steps and procedures must be put in place to manage situations where excess water builds up in the pollution control dams. • Pollution control dams must be operated empty as far as practicable and cannot fulfil the same role as water storage dams, unless specifically designed to fulfil both purposes. • Water reuse from the pollution control dams should be maximised.
Residual impact
Proper water management, along with adequately designed infrastructure should result in no accidental spillages, other than those resulting from extreme rainfall and discharges within the ambit of the law. Based on the assumption that proper management will take place and that infrastructure is adequately sized, the residual impacts will be low. Impacts could occur during the life of the mine.
Cumulative impact
The impacts resulting from contaminated water discharges will result in short term water quality deterioration in the three tributaries and the Wilge River provided the discharges are isolated events. The impacts resulting from contaminated water discharges are likely to result in water quality deterioration in the three tributaries and the Wilge River.
Impact rating table
Operational Phase Impact: Contaminated water discharge Prior to mitigation Probability Duration Scale Magnitude Impact score Impact 5 4 3 6 65 High Post mitigation Probability Duration Scale Magnitude Impact score Impact 1 1 3 6 10 Low
10.4.2 Loss of catchment yield
Impact assessment
During the operational phase, storm water generated from the open pits, overburden stockpiles and surrounding areas considered as dirty, will be collected in the dirty water system. This water would have contributed to the flow in the three tributaries and the Wilge River. The loss of catchment yield will result in a small reduction in flow in the catchment of the three tributaries and the Wilge River. This loss is quantified in Table 15.
Member: B Randell BSc Eng (Civil), PhD, PrEng. www.ilandawater.co.za
March 2019 31 0122-Rep-001 Rev4
Table 15:Loss of catchment yield Parameter North block impact North block impact East block impact on Northern on Western tributary tributary
Dirty catchment MAR* 0 m3 13 165 m3 25 173 m3 (Volume lost) Impact on the Wilge N/A 0.1% of MAR 0.2% of MAR River (0.03 mm) (0.06 mm) Impact on the Western N/A 2.4% of MAR N/A tributary (0.7 mm) Impact on the Eastern N/A N/A 11% of MAR tributary (3.5 mm) Impact on the Northern N/A N/A N/A tributary * Note: Assuming maximum pit extent Note: MAR is mean annual runoff Refer to Figure 1 on page 2 for stream locations.
Mitigation
As is best practice, dirty areas should be minimised. This will have the dual benefit of smaller dirty water management systems and reduction in catchment yield loss. This must include the separation of overburden stockpiles into topsoil, softs (uncontaminated) and hards (contaminated).
The open cast operations should be rehabilitated to return as much storm water to the environment as possible.
Residual impact
Once open cast mining ceases and effective rehabilitation is completed, the area will once again contribute to the catchment yield. Run-off from rehabilitated spoils will be negligibly reduced due to slightly higher infiltration but this impact is insignificant.
Cumulative impact
The impacts on the three tributaries and the Wilge River will be small.
Member: B Randell BSc Eng (Civil), PhD, PrEng. www.ilandawater.co.za
March 2019 32 0122-Rep-001 Rev4
Impact rating table
Operational Phase Impact: Loss of catchment yield Prior to mitigation Probability Duration Scale Magnitude Impact score Impact 5 4 2 6 60 High Post mitigation Probability Duration Scale Magnitude Impact score Impact 5 4 0 1 25 Low
10.4.3 Impacts due to wash bays and workshops
Impact assessment
Organic and nutrient pollution may result from the wash bays and workshop areas. These areas should be bunded and all water should be contained, collected and routed to an appropriate treatment facility. Impacts are likely to be low and will last during the life of the mine.
Mitigation
Mitigation of the impacts should include the following: • All drains that collect the wash water and storm water must be maintained regularly. These should be free of debris and silt. • All diversion canals, trenches and conduits must be designed to convey run-off from a 50-year design storm. • The wash bays and workshops must be equipped with oil separators to remove hydrocarbons from wash down water.
Residual impact
The residual impacts of the wash bays and workshops will probably be low. The impacts will occur for the life of the mine.
Cumulative impact
There are no known significant upstream sources of hydrocarbon pollutants apart from farming activities. These impacts will have a small detrimental effect on the water quality in the receiving waters.
Member: B Randell BSc Eng (Civil), PhD, PrEng. www.ilandawater.co.za
March 2019 33 0122-Rep-001 Rev4
Impact rating table
Operational Phase Impact: Wash bays and workshops Prior to mitigation Probability Duration Scale Magnitude Impact score Impact 2 1 3 4 16 Low Post mitigation Probability Duration Scale Magnitude Impact score Impact 1 1 3 4 8 Low
10.4.4 Impacts due to burst water pipes
Impact assessment
Water pipes will transport polluted water between the pollution control dams and the washing plant as well as between other facilities on the colliery. Dirty water will also be pumped from the Northern workings to the Eastern workings. If any of these pipes burst, significant quantities of poor quality water could be pumped into the environment. Mitigation
Mitigation of the impacts should include the following: • Pipe lines should be subjected to frequent patrols. An efficient system of reporting should be available to allow the immediate tripping of pumps. • Where practical, pipelines should be installed within dirty areas.
Residual impact
The residual impacts of a pipe line burst could be the contamination of the soil in the location of the burst. Salts will be introduced into the upper soil strata.
Cumulative impact
The impacts resulting from burst dirty water pipes will result in short term water quality deterioration in the three tributaries and the Wilge River, provided the discharges are isolated events. The impacts resulting from contaminated water discharges are likely to result in water quality deterioration in the three tributaries and the Wilge River.
Member: B Randell BSc Eng (Civil), PhD, PrEng. www.ilandawater.co.za
March 2019 34 0122-Rep-001 Rev4
Impact rating table
Operational Phase Impact: Burst water pipes Prior to mitigation Probability Duration Scale Magnitude Impact score Impact 4 2 3 6 44 Moderate Post mitigation Probability Duration Scale Magnitude Impact score Impact 3 2 2 4 24 Low
10.4.5 Impacts due to extreme flooding
Impact assessment
Various infrastructures on the colliery will be in close proximity to rivers. All facilities that make up the colliery should be constructed outside the 50-year and 100-year floodline by law. If the flooding is more severe than the 50-year or 100-year event, infrastructure may be damaged, and pollutants may be washed out. During such events, the three tributaries and the Wilge River will have large assimilative capacity and resultant impacts will be relatively small. Mitigation
If facilities have to be located within the floodlines, they should be protected by appropriate levees and flood diversion berms. There are no further mitigation measures necessary to cater for such extreme rainfall events.
Residual impact
The residual impacts in the three tributaries and the Wilge River will depend on what is washed into the river systems. If water is washed into the river systems, the residual impacts will be small as all pollutants will be washed into the downstream river systems and diluted. The large flow volumes will ensure that low concentrations of pollutants are transported downstream and residual impacts are likely to be small. If solids such as discards are washed into the river systems, the residual impacts could be significant.
Cumulative impact
The impacts resulting from extreme flooding are likely to be negligible in the short term. If solids are washed into the river systems, the cumulative impacts will be negative and water quality deterioration will occur.
Member: B Randell BSc Eng (Civil), PhD, PrEng. www.ilandawater.co.za
March 2019 35 0122-Rep-001 Rev4
Impact rating table
Operational Phase Impact: Extreme flooding Prior to mitigation Probability Duration Scale Magnitude Impact score Impact 1 1 3 4 8 Low Post mitigation Probability Duration Scale Magnitude Impact score Impact 1 1 3 4 8 Low
10.4.6 Impacts due to vehicle fleet-related pollution
Impact assessment
During the operational phase a significant number of vehicles will be driving around the site. In addition to this, fuels are stored on site and chemicals are used during normal operational activities. This may result in the following impacts: • If the mining vehicles are poorly maintained hydrocarbon spills could cause pollution if washed off roads by storm water. • Vehicle wash bays are a common source of hydrocarbon pollutants. • Leaks from fuel depots could result in surface water pollution. • Spillage and unsafe storage of chemicals could result in surface water contamination.
The affected areas will be the entire mining area. Impacts will be medium term and will cease after the cessation of mining. If soils have become contaminated, this will leach out over a prolonged period.
Mitigation
Mitigation of the impacts should include the following: • All mining vehicles should be well maintained and inspected for hydrocarbon leaks weekly. • Wash bay discharge water should flow through an oil separator. • Fuel depots and refuelling areas should be bunded. • Chemicals should be stored in a central secure area. Regular training on the responsible handling of chemicals should be undertaken. If contract mining is being used, responsible handling of chemicals and vehicle maintenance should be a key performance objective of the mining contractor.
Residual impact
If limited soil contamination occurs, the residual impacts will probably be very low.
Member: B Randell BSc Eng (Civil), PhD, PrEng. www.ilandawater.co.za
March 2019 36 0122-Rep-001 Rev4
Cumulative impact
There are no known significant upstream sources of hydrocarbon pollutants, although farming activities in the catchment could result in hydrocarbon pollution. Hydrocarbons are currently not measured in the Wilge River and it is unlikely that significant amounts of hydrocarbon pollution exist in the three tributaries and the Wilge River.
Impact rating table
Operational Phase Impact: Vehicle fleet related pollution Prior to mitigation Probability Duration Scale Magnitude Impact score Impact 3 2 2 4 24 Low Post mitigation Probability Duration Scale Magnitude Impact score Impact 2 2 2 4 16 Low
10.5 Impacts During the Decommissioning Phase of the Project
10.5.1 Impacts due to the removal of surface infrastructure
Impact assessment
During the decommissioning phase, most impacts will be associated with the removal of surface infrastructure, final closure of the open cast workings and removal and rehabilitation of the ROM stockpile and slurry pond footprints, the discard dump and other dirty areas. Haul roads will be removed, as will berms and diversion trenches. During this process, short term impacts will be moderate, as heavy earth-moving machinery will disturb large areas. Previously vegetated areas may be disturbed which will increase erosion potential. These short term impacts will give way to long term benefits. Mitigation
Apart from due diligence care while performing decommissioning tasks, no mitigation is necessary. Due diligence care includes the following: • Plant should be well maintained to ensure that hydrocarbon spills are minimised. • Existing roads should be used where possible. • New disturbed areas should be minimised.
Residual impact
The residual impacts will probably be very low due to the temporary nature of the impact. Large storm flows in the three tributaries and the Wilge River will wash the excess sediment
Member: B Randell BSc Eng (Civil), PhD, PrEng. www.ilandawater.co.za
March 2019 37 0122-Rep-001 Rev4
into downstream river systems. These sediment loads are likely to be very small in relation to the sediment loads in the three tributaries and the Wilge River.
Cumulative impact
The newly disturbed areas will add to sediment loads produced by erosion from upstream agricultural activities. While it occurs, the impact will be significant compared to upstream impacts of a similar nature. The impact will be temporary and will cease once the affected areas are vegetated.
Impact rating table
Decommissioning Phase Impact: Removal of surface infrastructure Prior to mitigation Probability Duration Scale Magnitude Impact score Impact 5 2 2 6 50 Moderate Post mitigation Probability Duration Scale Magnitude Impact score Impact 5 2 2 2 30 Low
10.6 Impacts After the Closure Phase of the Project
10.6.1 Impacts due to open cast workings decant
Impact assessment
The groundwater study has not been completed at the time of writing. Whether or not the rehabilitated open cast workings will decant, still needs to be determined. For the surface water impact assessment, a conservative approach is followed and it is assumed that decant may occur from the rehabilitated open cast workings. Should the groundwater study prove that decant will not occur from the rehabilitated open cast workings, this impact assessment will become irrelevant.
After the colliery is closed, contaminated water management becomes passive. Groundwater inflows and recharge through the rehabilitated spoils may create decant from the open cast workings. This decant will be driven by rainfall recharge through the surface and groundwater inflows. The decant water quality is likely to be poor and will contaminate the three tributaries and the Wilge River. Decant flows will likely be seasonal and volumes will be dependent on the quality of rehabilitation done and the degree of surface subsidence. Poor rehabilitation will increase the decant volumes. The water quality is likely to remain poor in the long term (>20 years). Eventually as pollutants are leached out of the workings, the seepage water quality will improve.
Member: B Randell BSc Eng (Civil), PhD, PrEng. www.ilandawater.co.za
March 2019 38 0122-Rep-001 Rev4
Mitigation
Mitigation of the impacts should include the following: • Surface subsidence that creates ponding should be avoided. • During the rollover mining, contaminated spoils should be placed at the base of the open cast pit where they can be permanently flooded. The uncontaminated spoils should be placed in the top horizons of the rehabilitated backfill. • Should passive mitigation measures not be suitable, active alternatives can be considered such as some form of treatment, prior to release.
Residual impact
The residual impacts will be dependent on the quality of rehabilitation and whether decant occurs. If decant is able to be prevented, impacts are expected to be negligible. If the rehabilitation quality is poor and/or groundwater contributions cause decant, impacts could be significant, particularly during the dry season when there is little assimilative capacity in the three tributaries and the Wilge River.
Cumulative impact
If decant is able to be prevented, the cumulative impacts will be negligible. Should decant occur, the impacts resulting from decant will result in long term water quality deterioration in the three tributaries and the Wilge River.
Impact rating table
If mitigation prevents decant, the following table applies:
Closure Phase Impact: Mine water decant Prior to mitigation Probability Duration Scale Magnitude Impact score Impact 5 5 3 6 70 High Post mitigation Probability Duration Scale Magnitude Impact score Impact 0 0 0 0 0 Low
Should mitigation be unsuccessful and decant occurs, the following table applies:
Member: B Randell BSc Eng (Civil), PhD, PrEng. www.ilandawater.co.za
March 2019 39 0122-Rep-001 Rev4
Closure Phase Impact: Mine water decant Prior to mitigation Probability Duration Scale Magnitude Impact score Impact 5 5 3 6 70 High Post mitigation Probability Duration Scale Magnitude Impact score Impact 5 5 3 4 60 High
11 REFERENCES
Adamson, P.T., Southern African Storm Rainfall, Department of Environment Affairs, Technical Report TR102, Pretoria, 1981.
Middleton, B.J. and Bailey, A.K., Water Resources of South Africa, 2005 study (WR2005), 2009. WRC Report No TT 382/08.
Midgley, D.C., Pitman, W.V., Middleton, B.J. Surface Water Resources of South Africa, 1990. WRC Report No 298/2.1/94, Volume 2.
Department of Water Affairs and Forestry, 1996. South African Water Quality Guidelines (second edition), Volume 1 : Domestic water Use.
Department of Water Affairs and Forestry, 1996. South African Water Quality Guidelines (second edition), Volume 2 : Recreational Water Use.
Department of Water Affairs and Forestry, 1996. South African Water Quality Guidelines (second edition), Volume 3 : Industrial Water Use.
Department of Water Affairs and Forestry, 1996. South African Water Quality Guidelines (second edition), Volume 4 : Agricultural Water Use: Irrigation.
Department of Water Affairs and Forestry, 1996. South African Water Quality Guidelines (second edition), Volume 5 : Agricultural Water Use: Livestock Watering.
Department of Water Affairs and Forestry, 1996. South African Water Quality Guidelines (second edition), Volume 7 : Aquatic Ecosystems.
ILANDA WATER SERVICES CC
BN Randell C:\ILANDA\ILANDA 2019 ONWARDS\GEOVICON\WELGELEGEN\122-REP-001 REV 4\0122-REP-001 REV4 WELGELEGEN HYDROLOGICAL EVALUATION.DOCX
Member: B Randell BSc Eng (Civil), PhD, PrEng. www.ilandawater.co.za
Member: B Randell BSc Eng (Civil), PhD, PrEng. www.ilandawater.co.za
APPENDIX 2
Updated Groundwater Study
Years of Water & Environmental Science
MODEL UPDATE
FOR
WELGELEGEN COLLIERY
GPT Reference Number: GEWEL-18-3633 Client Reference Number: N/A Version: Draft ver. 1 Date: December 2018
Compiled for:
GEOVICON ENVIRONMENTAL (PTY) LIMITED
Geo Pollution Technologies – Gauteng (Pty) Ltd 81 Rauch Avenue Georgeville 0184
P.O. Box 38384 Garsfontein East 0060
Tel: +27 (0)12 804 8120 Fax: +27 (0)12 804 8140
Geo Pollution Technologies – Gauteng (Pty) Ltd
Report Type: Hydrogeological Study Report for Water Use License Application Project Title: Hydrogeological Study for Welgelegen Colliery Compiled For: Geovicon Environmental (Pty) Limited Compiled By: V. Naidoo, M.Sc. Pr.Sci.Nat, G. J. du Toit, D.Sc., Pr.Sci.Nat. Reviewed By: M. Burger; M.Sc., Pr.Sci.Nat. GPT Reference: GEWEL-18-3633 Version: Draft ver.1. Date: December 2018 Distribution List (Current Version): • Geovicon Environmental (Pty) Limited
Disclaimer: The results and conclusions of this report are limited to the Scope of Work agreed between GPT and the Client for whom this investigation has been conducted. All assumptions made and all information contained within this report and its attachments depend on the accessibility to and reliability of relevant information, including maps, previous reports and word-of-mouth, from the Client and Contractors. All work conducted by GPT is done in accordance with the GPT Standard Operating Procedures. GPT is an ISO 9001 accredited Company.
Copyright: The copyright in all text and other matter (including the manner of presentation) is the exclusive property of Geo Pollution Technologies – Gauteng (Pty) Ltd, unless where referenced to external parties. It is a criminal offence to reproduce and/or use, without written consent, any matter, technical procedure and/or technique contained in this document. This document must be referenced if any information contained in it is used in any other document or presentation.
Declaration: I hereby declare: 1. I have no vested interest (present or prospective) in the project that is the subject of this report as well as its attachments. I have no personal interest with respect to the parties involved in this project. 2. I have no bias with regard to this project or towards the various stakeholders involved in this project. 3. I have not received, nor have I been offered, any significant form of inappropriate reward for compiling this report.
(electronic signature) (electronic signature) V. Naidoo, M.Sc. Pr.Sci.Nat G.J. du Toit; D.Sc.,Pr.Sci.Nat Professional Natural Scientist (No 117153) Professional Natural Scientist (No 400043/86) Geo Pollution Technologies – Gauteng (Pty) Ltd Geo Pollution Technologies – Gauteng (Pty) Ltd This report was reviewed by:
(electronic signature) M. Burger; M.Sc., Pr.Sci.Nat Professional Natural Scientist (No 400296/12) Customer Satisfaction: Feedback regarding the technical quality of this report (i.e. methodology used, results discussed and recommendations made), as well as other aspects, such as timeous completion of project and value of services rendered, can be posted onto GPT’s website at address: http://www.gptglobal.com/feedback.htm.
Model Update Report for Welgelegen Colliery- October 2018 i Geo Pollution Technologies – Gauteng (Pty) Ltd
EXECUTIVE SUMMARY
Geo Pollution Technologies (Pty) Ltd (GPT) was appointed by Geovicon Environmental (Pty) Limited (Geovicon) to update the numerical groundwater model and assess the in-pit storage at Welgelen Colliery. The loss of wetland flow contribution as a result of mining should also be quantified.
The following scope of work was addressed by the study:
• Impact Predictions
• Groundwater Risk Assessment
• Groundwater Management Options and Mitigation Measures
The following was concluded from the actions performed to address the scope of work:
The site is located on the farm Welgelegen 221 IR which is located approximately 20 km east of Delmas in the Mpumalanga Province.
The area is characterised by a gently undulating topography and in the area of the site the slope is more or less in the order of 1:125 (0.008).
Locally drainage is towards the tributary of the Wilge River that flows approximately 2 km west of the proposed mining site in a northerly direction, through the farm Welgelegen. On larger scale, drainage occurs in a northerly direction towards the generalised flow of the Wilge River.
Climatic data was obtained from the DWS weather station Bronkhorstspruit dam (rainfall data and evaporation data) for the Delmas area. The mine is located in the summer rainfall region of Southern Africa with precipitation usually occurring in the form of convectional thunderstorms. The average annual rainfall (measured over a period of 51 years) is approximately 733 mm, with the high rainfall months between October and March.
The area is characterised by consolidated sedimentary layers of the Karoo Supergroup. It consists mainly of sandstone, shale and coal beds of the Vryheid Formation of the Ecca Group and is underlain by the Dwyka Formation of the Karoo Supergroup. Jurassic dolerite intrusions occur throughout the area in the form of sills and outcrops is found throughout the whole area.
According to the 1:500 000 General Hydrogeological Map1 the Karoo Supergroup typically act as secondary aquifers (intergranular and fractured rock aquifers). However, the multi-layered weathering system present on these rocks could prove to have up to two aquifer systems present in the form of a shallow, regolith aquifer with a weathered, intergranular soft rock base associated with the contact of fresh bedrock and the weathering zone; and a fractured bedrock aquifer. These aquifer systems are discussed below.
During the hydrocensus, 5 boreholes were available for groundwater level measurement. The groundwater levels varied between a minimum of 4.63 m and a maximum of 10.7 m below ground level.
Water samples were collected from 1 borehole and 5 surface water points. The water results are compared with the maximum recommended concentrations for domestic use as defined by the SANS 241-1: 2015 target water quality limits.
1 Haupt, C.J., (1995). An explanation of the 1:500 000 General Hydrogeological Map. Rustenburg 2526. DWAF.
Model Update Report for Welgelegen Colliery- October 2018 ii Geo Pollution Technologies – Gauteng (Pty) Ltd
• TDS, Sulphate, Manganese and Aluminium were found to be above the SANS 241 limits in the PCD sample. pH was also found to be outside the SANS limits in the PCD sample.
• Iron and aluminium were found to be above the SANS limits in SWUS.
• Sulphate was found to be above the SANS limits in SWMS.
• Manganese exceeds the SANS limits in the onsite in use borehole B1.
• The elevated concentrations of sulphate, manganese and iron on site are likely a result of the coal mining activities in the area.
The GDT calculated a vulnerability value of 55% for the aquifer which is classified as medium. Based on information collected during the hydrocensus it can be concluded that the aquifer system in the study area can be classified as a “Major Aquifer System”, based on the fact that the local population is dependent on groundwater. A Groundwater Quality Management Index of 8 was estimated for the study area from the ratings for the Aquifer System Management Classification. According to this estimate a high level groundwater protection is required for the aquifer.
Geochemical assessment
GPT collected 3 geochemical samples at the Welgelegen Colliery on the 16th of October 2018. Two samples were collected at discard positions and one overburden sample was collected in pit.
The samples were sent to SANAS accredited laboratory (UIS Organic Laboratory (Pty) Ltd) for analysis. All three samples were analysed by quantitative X-ray diffraction, ICP-MS and a leach test.
In summary the report indicates the following regarding the geochemical samples:
The main characteristic of a hypothetical coal mine has been sketched using the chemical analyses of discard material, XRD analyses of those sample, as well as the leachate emanating from these rocks under a controlled leachate test. The result stipulate that rocks stored above the water table (saturated zone) would be more prone to the generation of AMD, compared to rocks underneath the water table (saturated zone).
Hydrogeological Impacts
Based on the numerical flow and transport modelling performed, the following hydrogeological impacts were identified:
During Mining
• The Western Opencast is expected to receive 1 000 m3/d from groundwater seepage. The drawdown from this mine is expected to influence water levels in the North-western Tributary of the Wilge River. Expected water level decline at these receptors is expected to be approximately 10 m.
• The Eastern Opencast is expected to receive groundwater inflows of 500 m3/d. The drawdown from this mine is expected to influence water levels in the Eastern Tributary of the Wilge River. Expected water level decline at these receptors is expected to be 5 m.
Post-Mining
• Contamination from Western Opencast is expected to affect North-western Tributary of the Wilge River with expected concentration increases of 1000 mg/l with regards to sulphate. The Western Opencast is expected to rebound within 20 years.
Model Update Report for Welgelegen Colliery- October 2018 iii Geo Pollution Technologies – Gauteng (Pty) Ltd
• Contamination from the Eastern Opencast is expected to affect Eastern Tributary of the Wilge River with expected concentration increases of 2000 mg/l with regards to sulphate. The Eastern is expected to rebound within 30 years.
• However, should the mine discard be placed under water, the contamination to the North- western Tributary reduce to about 100 mg/l, and those at the Eastern Tributary reduce to about 50 mg/l. There is thus a big environmental advantage of placing discard below the groundwater level.
• With regard to the post mining impacts, the following also needs to be pointed out: o Although no decant is predicted by the model, the groundwater level is predicted to rise to very close to surface in the north-east of the western opencast and in the south- west of the eastern opencast. Should there be occasional seepage to surface, it will be to these areas. o Plume movement from the opencasts will be mostly towards the streams at a low speed of about 10 m/y maximum, depending mainly on slope of the groundwater table. o The contours of plume movement indicate that contamination might reach the Wilge River and its northwester tributary in about 30 to 50 years in the worst case scenario. However, the contamination is unlikely to have a lasting effect on the water courses as they are normally lined with a natural clay layer and thus poorly connected to the groundwater. o Furthermore, the streams are also normally dry and only carry water after rainfall events. This mass of water will wash down any contaminated seepage and dilute it to unmeasurable concentrations. o However, if the mine discard is placed underneath the groundwater level (as is being done right now), Figure 20 indicates that the sulphate reaching the water courses will be of low concentration. o It is also noticeable that the contamination from the plant area will move eastwards and eventually flow into the defunct western opencast at low concentrations. No impact on any stream is thus anticipated resulting from the plant contamination.
With regards to the wetlands the following can be seen:
• Wetlands along the Wilge River will not be affected at all during mining at Welgelegen. • However, the wetlands surrounding the tributaries could experience less flow during dry winter months.
Summer rainfall volumes are at least an order of magnitude more than deep groundwater flow and interflow combined, and the rainwater should replenish the wetlands seasonally. Thus, little impact is expected on the wetlands.
Recommendations
The following actions are recommended:
• The practice of depositing discard below the groundwater level is very promising from a groundwater environmental view, and should be maintained meticulously during future mining.
• The monitoring as recommended in the report should be established as soon as possible. Especially the Eastern Opencast does not have adequate monitoring boreholes at present.
Model Update Report for Welgelegen Colliery- October 2018 iv Geo Pollution Technologies – Gauteng (Pty) Ltd
• Regularly update the groundwater impact status report and numerical model against monitored data during operations, at least once more before closure.
• Water quantity and quality data should be collected on a regular, ongoing basis during mine operations. These data will be used to recalibrate and update the mine water management model, to prepare monitoring and audit reports, to report to the regulatory authorities against the requirements of the IWMP and other authorisations and as feedback to stakeholders in the catchment, perhaps via the CMA.
• The hydrocensus and risk assessment should at least be repeated once before closure to evaluate any impacts
Model Update Report for Welgelegen Colliery- October 2018 v Geo Pollution Technologies – Gauteng (Pty) Ltd
TABLE OF CONTENTS
Page
1 INTRODUCTION ...... 1
2 GEOGRAPHICAL SETTING ...... 1
2.1 SITE LOCATION, TOPOGRAPHY AND DRAINAGE ...... 1
2.2 CLIMATE ...... 4
3 SCOPE OF WORK ...... 5
3.1 PROJECT OBJECTIVES ...... 5
4 METHODOLOGY ...... 5
4.1 DESK STUDY ...... 5
4.2 FIELDWORK ...... 5
4.3 SAMPLING AND CHEMICAL ANALYSES ...... 5
4.3.1 Geochemical sampling ...... 5
4.3.2 Geochemical analysis ...... 6
4.4 GROUNDWATER RECHARGE CALCULATIONS ...... 6
4.5 GROUNDWATER MODELLING ...... 7
4.5.1 Numerical modelling ...... 7
4.5.2 Transport modelling ...... 7
5 PREVAILING GROUNDWATER CONDITIONS ...... 7
5.1 GEOLOGY ...... 7
5.1.1 Regional Geology ...... 7
5.2 HYDROGEOLOGY ...... 10
5.2.1 Unsaturated Zone - Shallow, regolith aquifer ...... 10
Model Update Report for Welgelegen Colliery- October 2018 vi Geo Pollution Technologies – Gauteng (Pty) Ltd
5.2.2 Saturated Zone - Fractured, bedrock aquifer ...... 10
5.3 GROUNDWATER LEVELS ...... 11
5.4 GROUNDWATER QUALITY ...... 15
5.4.1 Groundwater and surface water quality vs SANS standards ...... 15
5.4.2 Spatial analysis of groundwater and surface water quality ...... 15
6 AQUIFER CHARACTERISATION ...... 20
6.1 AQUIFER VULNERABILITY ...... 20
6.2 AQUIFER CLASSIFICATION ...... 21
6.3 AQUIFER PROTECTION CLASSIFICATION ...... 23
7 GEOCHEMICAL ASSESSMENT ...... 24
8 GROUNDWATER FLOW AND TRANSPORT MODELLING ...... 25
8.1 SOFTWARE MODEL CHOICE ...... 26
8.2 MODEL SET-UP AND BOUNDARIES ...... 26
8.3 GROUNDWATER ELEVATION AND GRADIENT ...... 26
8.4 GEOMETRIC STRUCTURE OF THE MODEL ...... 26
8.5 GROUNDWATER SOURCE AND SINKS ...... 27
8.6 CONCEPTUAL MODEL INPUT ...... 27
8.7 CALIBRATION OF THE NUMERICAL MODEL ...... 28
8.8 MODEL RUNS ...... 31
8.8.1 Pre-Mining ...... 31
8.8.2 During-Mining ...... 31
8.8.3 Post-Mining ...... 31
9 HYDROGEOLOGICAL IMPACTS ...... 33
Model Update Report for Welgelegen Colliery- October 2018 vii Geo Pollution Technologies – Gauteng (Pty) Ltd
9.1 OPERATIONAL PHASE IMPACTS ...... 33
9.1.1 Impacts on groundwater quantity ...... 33
9.1.2 Impacts on surface water ...... 34
9.1.3 Impacts on groundwater quality ...... 34
9.1.4 Groundwater management ...... 36
9.2 DECOMMISSIONING AND POST-CLOSURE PHASE IMPACTS ...... 39
9.2.1 Impacts on groundwater quantity ...... 39
9.2.2 Impacts on groundwater quality ...... 40
9.2.3 Cumulative effects ...... 43
9.2.4 Groundwater management ...... 43
10 IMPACT ON THE WETLANDS ...... 51
10.1 METHODOLOGY...... 51
10.2 CONCEPTUAL MODEL ...... 51
10.3 NUMERICAL MODEL ...... 51
10.3.1 Interflow ...... 52
10.3.2 Deep Groundwater Aquifer ...... 53
11 GROUNDWATER MONITORING SYSTEM ...... 57
11.1 GROUNDWATER MONITORING NETWORK ...... 57
11.1.1 Source, plume, impact and background monitoring ...... 57
11.1.2 System Response Monitoring Network ...... 57
11.1.3 Monitoring Frequency ...... 57
11.2 MONITORING PARAMETERS ...... 57
11.2.1 Abbreviated analysis (pollution indicators) ...... 58
Model Update Report for Welgelegen Colliery- October 2018 viii Geo Pollution Technologies – Gauteng (Pty) Ltd
11.2.2 Full analysis ...... 58
11.3 MONITORING BOREHOLES ...... 58
12 GROUNDWATER ENVIRONMENTAL MANAGEMENT PROGRAMME ...... 61
12.1 CURRENT GROUNDWATER CONDITIONS ...... 61
12.2 PREDICTED IMPACTS OF MINING ...... 61
12.3 RISK ASSESSMENT ...... 61
12.4 IMPACT ASSESSMENT ...... 62
12.4.1 Assessment Criteria ...... 62
12.4.2 Nature and Status ...... 65
12.4.3 Extent ...... 65
12.4.4 Duration ...... 65
12.4.5 Intensity ...... 65
12.4.6 Probability ...... 65
12.4.7 Level of Significance ...... 65
12.4.8 Identifying Potential Impacts with Mitigation Measures ...... 65
12.4.9 Impact Assessment ...... 66
12.5 MITIGATION MEASURES ...... 72
12.6 LOWERING OF GROUNDWATER LEVELS DURING OPERATIONS ...... 72
12.7 SPREAD OF GROUNDWATER POLLUTION POST-OPERATIONS ...... 73
13 POST-CLOSURE MANAGEMENT PLAN ...... 74
13.1 REMEDIATION OF PHYSICAL ACTIVITY ...... 74
13.2 REMEDIATION OF STORAGE FACILITIES...... 75
13.3 REMEDIATION OF ENVIRONMENTAL IMPACTS ...... 75
Model Update Report for Welgelegen Colliery- October 2018 ix Geo Pollution Technologies – Gauteng (Pty) Ltd
13.4 REMEDIATION OF WATER RESOURCE IMPACTS ...... 76
13.5 BACKFILL OF PITS ...... 77
14 CONCLUSIONS AND RECOMMENDATIONS ...... 78
14.1 RECOMMENDATIONS ...... 81
Model Update Report for Welgelegen Colliery- October 2018 x Geo Pollution Technologies – Gauteng (Pty) Ltd
LIST OF FIGURES
Page FIGURE 1: SITE LOCATION AND QUATERNARY CATCHMENT BOUNDARIES ...... 2 FIGURE 2: SITE TOPOGRAPHY ...... 3 FIGURE 3: CLIMATIC DATA REPRESENTATION ...... 4 FIGURE 4: REGIONAL GEOLOGY MAP (1:250 000 GEOLOGY SERIES MAP) ...... 9 FIGURE 5: CORRELATION GRAPH OF TOPOGRAPHY VS AVAILABLE GROUNDWATER LEVELS...... 13 FIGURE 6: CONTOURED WATER LEVELS OF THE WATER TABLE AQUIFER (UNCONFINED AQUIFER) 14 FIGURE 7: PIE DIAGRAMS FOR GROUNDWATER SAMPLES ...... 17 FIGURE 8: EXPLANATION OF THE HYDROCHEMICAL FACIES IN THE PIPER DIAGRAM ...... 18 FIGURE 9: PIPER DIAGRAM ...... 19 FIGURE 10: WATER LEVEL CALIBRATION GRAPH ...... 30 FIGURE 11: CALIBRATION OF THE NUMERICAL MODEL (5 M HEAD INTERVAL) ...... 45 FIGURE 12: CONE OF DEPRESSION DURING MINING ...... 46 FIGURE 13: REBOUND STAGE CURVE ...... 47 FIGURE 14: PREDICTED SPREAD OF POLLUTION POST-CLOSURE OF MINING – DISCARD ABOVE GROUNDWATER ...... 48 FIGURE 15: PREDICTED SPREAD OF POLLUTION POST-CLOSURE OF MINING – DISCARD BELOW GROUNDWATER ...... 49 FIGURE 16: PREDICTED SPREAD OF POLLUTION POST-CLOSURE OF MINING – PLANT AREA REHABILITATED ...... 50 FIGURE 17: INTERFLOW CONCEPTUAL MODEL ...... 54 FIGURE 18: 2D DESIGNATION OF OPENCASTS AND WETLANDS ...... 55 FIGURE 19: PROPOSED MONITORING POSITIONS ...... 60 FIGURE 20: ELEVATION DATA ...... 85 FIGURE 21: MODEL BOUNDARIES ...... 86 FIGURE 22: LATERAL DELINEATION OF THE REGIONAL MODEL ...... 87 FIGURE 23: LATERAL DELINEATION IN THE MINING AREA ...... 88 FIGURE 24: VERTICAL DELINEATION OF THE MODELLED AREA ...... 89
Model Update Report for Welgelegen Colliery- October 2018 xi Geo Pollution Technologies – Gauteng (Pty) Ltd
LIST OF TABLES
Page TABLE 1: CLIMATIC DATA ...... 4 TABLE 2: RECHARGE CALCULATION FOR THE SHALLOW UNCONFINED AQUIFER ...... 6 TABLE 3: AVAILABLE GROUNDWATER LEVEL STATISTICS ...... 12 TABLE 4: WATER QUALITIES COMPARED TO SANS 241-1:2015 GUIDELINES FOR HUMAN CONSUMPTION ...... 16 TABLE 5: RATINGS – AQUIFER SYSTEM MANAGEMENT AND SECOND VARIABLE CLASSIFICATIONS.. 21 TABLE 6: RATINGS - GROUNDWATER QUALITY MANAGEMENT (GQM) CLASSIFICATION SYSTEM ... 22 TABLE 7: GQM INDEX FOR THE STUDY AREA ...... 23 TABLE 8: LOCATION OF GEOCHEMICAL SAMPLES ...... 24 TABLE 9: XRD DATA GENERATED ON THE THREE COAL DISCARD SAMPLES COLLECTED...... 25 TABLE 10: TRACE ELEMENT ANALYSES ON DISCARD MATERIAL ...... 25 TABLE 11: MAJOR ELEMENT ANALYSES ON DISCARD MATERIAL ...... 25 TABLE 12: MAJOR AND TRACE ELEMENT ANALYSES ON LEACHATE FROM DISCARD MATERIAL ...... 25 TABLE 13: INPUT PARAMETERS TO THE NUMERICAL FLOW MODEL ...... 27 TABLE 14: OPTIMAL CALIBRATED AQUIFER PARAMETERS ...... 29 TABLE 15: CALIBRATION STATISTICS ...... 29 TABLE 16: SUMMARY OF POTENTIAL IMPACTS DURING OPERATION – DEWATERING ...... 35 TABLE 17: WATER RECHARGE-CHARACTERISTICS FOR OPENCAST MINING IN THE MPUMALANGA AREA (HODGSON AND KRANTZ, 1998) ...... 40 TABLE 18: SUMMARY OF POTENTIAL IMPACTS POST OPERATIONS ...... 42 TABLE 19: RESULTS OF DEEP GROUNDWATER FLOW (GD) AND INTERFLOW (GS) ON THE WETLANDS 56 TABLE 20: PROPOSED MONITORING POSITIONS (NEW BOREHOLES TO BE SITED BY GEOPHYSICS) . 59 TABLE 21: EFFECTS OF SULPHATE ON HUMAN HEALTH ...... 62 TABLE 22: EXPLANATION OF THE EIA CRITERIA ...... 64 TABLE 23: IMPACT EXTENT ...... 67 TABLE 24: IMPACT DURATION ...... 68 TABLE 25: IMPACT INTENSITY ...... 69 TABLE 26: IMPACT PROBABILITY ...... 70 TABLE 27: IMPACT SIGNIFICANCE ...... 71 TABLE 28: MITIGATION MEASURES FOR THE MANAGEMENT OF GROUNDWATER LEVEL LOWERING 72 TABLE 29: MITIGATION MEASURES FOR THE MANAGEMENT OF THE SPREAD OF GROUNDWATER CONTAMINATION ...... 73
Model Update Report for Welgelegen Colliery- October 2018 xii Geo Pollution Technologies – Gauteng (Pty) Ltd
LIST OF APPENDICES
Page APPENDIX I: HYDROCENSUS INFORMATION 82 APPENDIX II: GEOCHEMICAL DATA DESCRIPTION 83 APPENDIX III: NUMERICAL MODEL METHODOLOGY AND SETUP 84
Model Update Report for Welgelegen Colliery- October 2018 xiii Geo Pollution Technologies – Gauteng (Pty) Ltd
LIST OF ABBREVIATIONS
Abbreviation Explanation
ARD Acid Rock Drainage BPG Best Practice Guidelines CMS Catchment Management Strategy CSM Conceptual Site Model EC Electrical Conductivity EIA Environmental Impact Assessment EMP Environmental Management Plan IWRMP Integrated Water Resources Management Plan IWRM Integrated Water Resources Management Km2 Square Kilometre L/s Litres per second mamsl Metres above mean sea level Ml/d Megalitres per day m meter mm Millimetre mm/a Millimetres per annum mS/m Millisiemens per metre m3 Cubic metre MAP Mean Annual Precipitation MPRDA Mining and Petroleum Resources Development Act (Act No. 73 of 2002) 1989) NEMA National Environmental Management Act (Act No. 107 of 1998) NWA National Water Act (Act No. 36 of 1998) ppm Parts per million RDM Resource Directed Measures RQO Resource Quality Objective RWQO Resource Water Quality Objective TDS Total Dissolved Solids WMA Water Management Area WMP Water Management Plan
Model Update Report for Welgelegen Colliery- October 2018 xiv Geo Pollution Technologies – Gauteng (Pty) Ltd
DEFINITIONS
Definition Explanation
Aquiclude A geologic formation, group of formations, or part of formation through which virtually no water moves Aquifer A geological formation which has structures or textures that hold water or permit appreciable water movement through them. Source: National Water Act (Act No. 36 of 1998). Borehole Includes a well, excavation, or any other artificially constructed or improved underground cavity which can be used for the purpose of intercepting, collecting or storing water in or removing water from an aquifer; observing and collecting data and information on water in an aquifer; or recharging an aquifer. Source: National Water Act (Act No. 36 of 1998). Boundary An aquifer-system boundary represented by a rock mass (e.g. an intruding dolerite dyke) that is not a source of water, and resulting in the formation of compartments in aquifers.
Cone of Depression The depression of hydraulic head around a pumping borehole caused by the withdrawal of water. Confining Layer A body of material of low hydraulic conductivity that is stratigraphically adjacent to one or more aquifers; it may lie above or below the aquifer. Dolomite Aquifer See “Karst” Aquifer Drawdown The distance between the static water level and the surface of the cone of depression. Fractured Aquifer An aquifer that owes its water-bearing properties to fracturing. Groundwater Water found in the subsurface in the saturated zone below the water table. Groundwater Divide or The boundary between two groundwater basins which is represented Groundwater Watershed by a high point in the water table or piezometric surface. Groundwater Flow The movement of water through openings in sediment and rock; occurs in the zone of saturation in the direction of the hydraulic gradient. Hydraulic Conductivity Measure of the ease with which water will pass through the earth's material; defined as the rate of flow through a cross-section of one square metre under a unit hydraulic gradient at right angles to the direction of flow (m/d). Hydraulic Gradient The rate of change in the total hydraulic head per unit distance of flow in a given direction. Infiltration The downward movement of water from the atmosphere into the ground. Intergranular Aquifer A term used in the South African map series referring to aquifers in which groundwater flows in openings and void spaces between grains and weathered rock. Karst (Karstic) The type of geomorphological terrain underlain by carbonate rocks where significant solution of the rock has occurred due to flowing groundwater.
Model Update Report for Welgelegen Colliery- October 2018 xv Geo Pollution Technologies – Gauteng (Pty) Ltd
Definition Explanation Karst (Karstic) Aquifer A body of soluble rock that conducts water principally via enhanced (conduit or tertiary) porosity formed by the dissolution of the rock. The aquifers are commonly structured as a branching network of tributary conduits, which connect together to drain a groundwater basin and discharge to a perennial spring. Monitoring The regular or routine collection of groundwater data (e.g. water levels, water quality and water use) to provide a record of the aquifer response over time. Observation Borehole A borehole used to measure the response of the groundwater system to an aquifer test. Phreatic Surface The surface at which the water level is in contact with the atmosphere: the water table. Piezometric Surface An imaginary or hypothetical surface of the piezometric pressure or hydraulic head throughout all or part of a confined or semi-confined aquifer; analogous to the water table of an unconfined aquifer. Porosity Porosity is the ratio of the volume of void space to the total volume of the rock or earth material. Production Borehole A borehole specifically designed to be pumped as a source of water supply. Recharge The addition of water to the saturated zone, either by the downward percolation of precipitation or surface water and/or the lateral migration of groundwater from adjacent aquifers. Recharge Borehole A borehole specifically designed so that water can be pumped into an aquifer in order to recharge the ground-water reservoir. Saturated Zone The subsurface zone below the water table where interstices are filled with water under pressure greater than that of the atmosphere. Specific Capacity The rate of discharge from a borehole per unit of drawdown, usually expressed as m3/d•m. Specific Yield The ratio of the volume of water that drains by gravity to that of the total volume of the saturated porous medium. Storativity The volume of water an aquifer releases from or takes into storage per unit surface area of the aquifer per unit change in head. Transmissivity Transmissivity is the rate at which water is transmitted through a unit width of an aquifer under a unit hydraulic gradient. It is expressed as the product of the average hydraulic conductivity and thickness of the saturated portion of an aquifer. Unsaturated Zone (Also That part of the geological stratum above the water table where Termed Vadose Zone) interstices and voids contain a combination of air and water. Watershed (Also Termed Catchment in relation to watercourse or watercourses or part of a Catchment) watercourse means the area from which any rainfall will drain into the watercourses or part of a watercourse through surface flow to a common point or points. Source: National Water Act (Act No. 36 of 1998). Water Table The upper surface of the saturated zone of an unconfined aquifer at which pore pressure is equal to that of the atmosphere.
Model Update Report for Welgelegen Colliery- October 2018 xvi Geo Pollution Technologies – Gauteng (Pty) Ltd
1 INTRODUCTION
Geo Pollution Technologies (Pty) Ltd (GPT) was appointed by Geovicon Environmental (Pty) Limited (Geovicon) to update the numerical groundwater model and assess the in-pit storage at Welgelen Colliery.
The report is structured according to the requirements of the National Water Act, 1998 Regulations regarding the procedural requirements for water use licence applications and appeals 24 March 2017, Act N0. R. 267.
2 GEOGRAPHICAL SETTING
2.1 Site Location, Topography and Drainage
The site is located on the farm Welgelegen 221 IR which is located approximately 20 km east of Delmas in the Mpumalanga Province (Figure 1).
The topography (shown in Figure 2) can normally be used as a good first approximation of the hydraulic gradient in the unconfined aquifer. This discussion will focus on the slope and direction of fall of the area under investigation, features that are important from a groundwater point of view.
The area is characterised by a gently undulating topography and in the area of the site the slope is more or less in the order of 1:125 (0.008).
Locally drainage is towards the tributary of the Wilge River that flows approximately 2 km west of the proposed mining site in a northerly direction, through the farm Welgelegen. A non-perennial tributary of the Wilge River flows along the most southern border of the site and then change direction to flow, approximately 2 km north-west of the proposed mining site, into the Wilge River. There are a number of dams on the farm, as well as two perennial pans and two small non- perennial pans. On larger scale, drainage occurs in a northerly direction towards the generalised flow of the Wilge River.
Model Update Report for Welgelegen Colliery- October 2018 1 Geo Pollution Technologies – Gauteng (Pty) Ltd
Figure 1: Site Location and Quaternary Catchment Boundaries
Model Update Report for Welgelegen Colliery- October 2018 2 Geo Pollution Technologies – Gauteng (Pty) Ltd
Figure 2: Site Topography
Model Update Report for Welgelegen Colliery- October 2018 3 Geo Pollution Technologies – Gauteng (Pty) Ltd
2.2 Climate
Climatic data was obtained from the DWA weather station at the Bronkhorstspruit dam (rainfall data and evaporation data) for the Delmas area (Table 1)2. The mine is located in the summer rainfall region of Southern Africa with precipitation usually occurring in the form of convectional thunderstorms. The average annual rainfall (measured over a period of 51 years) is approximately 733 mm, with the high rainfall months between October and March.
Table 1: Climatic Data
Average monthly Mean monthly Month rainfall (mm) evaporation
January 138.5 168 February 85.8 145 March 92.4 136.4 April 43.1 105.5 May 14.9 85.3 June 6.8 67.1 July 2.6 74.5 August 7.2 103.6 September 22.5 141.6 October 75.2 165.3 November 110.9 163.6 December 122.5 176.2 Annual 732.7 1523.8
200 1600 180 1400 160 1200 140 120 1000 Rainfall 100 800 80 600 Evaporation 60
Averages Averages mm in 400 MAP 40 20 200 MAE 0 0
Figure 3: Climatic data representation
2 Department of Water Affairs (DWA): www.dwa.gov.za
Model Update Report for Welgelegen Colliery- October 2018 4 Geo Pollution Technologies – Gauteng (Pty) Ltd
3 SCOPE OF WORK
Update the previous groundwater model to predict and quantify the potential impacts of the in pit residue disposal and the additional opencast mining to the east of the site. The loss of wetland flow contribution as a result of mining should also be quantified.
3.1 Project Objectives
Within the scope of work the groundwater study aimed to address the following:
• Impact Predictions
• Groundwater Risk Assessment
• Groundwater Management Options and Mitigation Measures
4 METHODOLOGY
4.1 Desk Study
This entailed the gathering of information through the collation, scrutiny and evaluation of available and relevant meteorological, geographical, geological, hydrogeological and water quality data.
4.2 Fieldwork
The hydrocensus was done as a site familiarisation exercise and the collection of data from the study area and surrounding environments. It comprised a census of key boreholes, wells, springs and any other groundwater related information.
4.3 Sampling and Chemical Analyses
The sampling and analyses conducted for the study are discussed in the following paragraphs.
4.3.1 Geochemical sampling
The generation, release, mobility, and attenuation of acid rock drainage (ARD) is a complex process governed by a combination of physical, chemical, and biological factors. Neutral mine drainage (NMD) and saline drainage (SD) are governed by similar factors but may or may not involve the oxidation of sulphides. Whether ARD, NMD, or SD enters the environment depends largely on the characteristics of the sources and pathways. Characterization of these features is therefore key to the prediction, prevention, and management of drainage impacted by the products of sulphide oxidation.
The geochemical sampling was done within the scope of work to collect sufficient data to answer the following questions:
• Is ARD likely to occur and what are the potential sources?
• What type of chemistry is expected? • When is likely to start and how much will be generated?
• What are the significant pathways that transport contaminants to the receiving environment and can those contaminants be attenuated along those pathways?
• What are the anticipated environmental impacts?
Model Update Report for Welgelegen Colliery- October 2018 5 Geo Pollution Technologies – Gauteng (Pty) Ltd
• What can be done to prevent or mitigate/manage ARD?
The geochemical sampling was guided by the Global Acid Rock Drainage Guide as developed by the International Network for Acid Prevention.3
4.3.2 Geochemical analysis
4.3.2.1 Liquid extraction
Major cations, anions and trace elements were determined in rock or soil samples after liquid extractions were performed
4.3.2.2 Solid extraction
Solid extractions was done through Distilled Water, Acid Rain, TCLP, Peroxide, Acid (Aqua Regia), etc.
4.3.2.3 Metals
Total metals in solids were determined after extractions by either AAS, ICP-OES or ICP-MS.
4.3.2.4 X-Ray Diffraction Spectroscopy
X-Ray Powder Diffraction (XRD) is an analytical technique primarily used for phase identification of a crystalline material and can provide information on unit cell dimensions. The analysed material is finely ground, homogenised, and average bulk composition is determined.
Therefore, XRD provides the composition of a rock material sample in terms of the crystalline minerals present. However, it is important to note that XRD can only report the crystalline phases present above an abundance of 1 weight%.
4.4 Groundwater Recharge Calculations
Recharge to the shallow, unconfined aquifer was calculated using the RECHARGE program developed by the Institute for Groundwater Studies at the University of the Free State, South Africa. The calculated recharge percentage equates to approximately 3.7%.
Table 2: Recharge calculation for the shallow unconfined aquifer
Recharge Estimation
Certainty (Very High = 5; Method mm/a % of rainfall Low = 1)
Various schematic maps Soil 44.3 6.0 3 Geology 24.0 3.3 3 Vegter 32.0 4.4 3 Acru 10.0 1.4 3 Harvest Potential 25.0 3.4 3
3 http://www.gardguide.com
Model Update Report for Welgelegen Colliery- October 2018 6 Geo Pollution Technologies – Gauteng (Pty) Ltd
4.5 Groundwater Modelling
Modelling was performed as a representation of a groundwater flow system and/or geochemical system that attempts to mimic the natural processes. It is therefore a simplified version of the natural system, compiled with geological, hydrogeological, hydrological and meteorological data, which utilises governing equations to incorporate all this data and simulates the hydraulic properties or geochemical properties of the system.
These models were utilised to provide a quantitative understanding of a groundwater system in terms of existing conditions as well as induced stresses, which inherently aids in the identification of cost-effective and efficient solutions to groundwater contamination and management challenges.
4.5.1 Numerical modelling
Numerical groundwater modelling is considered to be the most reliable method of anticipating and quantifying the likely impacts on the groundwater regime.
The finite difference numerical model was created using AquaVeo’s Groundwater Modelling System (GMS10.0) as Graphical User Interface (GUI) for the well-established Modflow and MT3DMS numerical codes.
MODFLOW is a 3D, cell-centred, finite difference, saturated flow model developed by the United States Geological Survey. MODFLOW can perform both steady state and transient analyses and has a wide variety of boundary conditions and input options. It was developed by McDonald and Harbaugh of the US Geological Survey in 1984 and underwent eight overall updates since. The latest update (MODFLOW NWT) incorporates several improvements extending its capabilities considerably, the most important being the introduction of the new Newton formulation and solver, vastly improving the handling of dry cells which has proven to be problematic in the past.
4.5.2 Transport modelling
Transport modelling was performed using MT3DMS. MT3DMS is a 3-D model for the simulation of advection, dispersion, and chemical reactions of dissolved constituents in groundwater systems. MT3DMS uses a modular structure similar to the structure utilized by MODFLOW, and is used in conjunction with MODFLOW in a two-step flow and transport simulation. Heads are computed by MODFLOW during the flow simulation and utilized by MT3DMS as the flow field for the transport portion of the simulation.
5 PREVAILING GROUNDWATER CONDITIONS
5.1 Geology
5.1.1 Regional Geology
The investigated area falls within the 2628 East Rand1:250 000 geology series maps. An extract of these maps is shown in Figure 4.
The area is characterised by consolidated sedimentary layers of the Karoo Supergroup. It consists mainly of sandstone, shale and coal beds of the Vryheid Formation of the Ecca Group and is underlain by the Dwyka Formation of the Karoo Supergroup. Jurassic dolerite intrusions occur throughout the area in the form of sills and outcrops is found throughout the whole area. Small outcrops of the Daspoort (shale and quartzite) and Hekpoort (andesite) formations are also found
Model Update Report for Welgelegen Colliery- October 2018 7 Geo Pollution Technologies – Gauteng (Pty) Ltd on the farm Welgelegen. The proposed opencast mining areas falls within the Witbank Coalfield, which extends from Belfast in the north- east to Springs in the south- west covering a surface area of approximately 9000 km2.
A detailed description of the regional and local geology can be found in the 2013 hydrogeological report compiled by GPT4
4 Available on request from mailto:[email protected].
Model Update Report for Welgelegen Colliery- October 2018 8 Geo Pollution Technologies – Gauteng (Pty) Ltd
Figure 4: Regional Geology Map (1:250 000 geology series map)
Model Update Report for Welgelegen Colliery- October 2018 9 Geo Pollution Technologies – Gauteng (Pty) Ltd
5.2 Hydrogeology
According to the 1:500 000 General Hydrogeological Map5 the rocks of the Karoo Supergroup typically act as secondary aquifers (intergranular and fractured rock aquifers). However, the multi- layered weathering system present on these rocks could prove to have up to two aquifer systems present in the form of a shallow, regolith aquifer with a weathered, intergranular soft rock base associated with the contact of fresh bedrock and the weathering zone; and a fractured bedrock aquifer. These aquifer systems are discussed below.
5.2.1 Unsaturated Zone - Shallow, regolith aquifer
The main source of recharge into the shallow aquifer is rainfall that infiltrates the aquifer through the unsaturated (vadose) zone. Vertical movement of water is faster than lateral movement in this system as water moves predominantly under the influence of gravity. This aquifer is comprised of transported alluvium and in-situ weathered sediments and is underlain by consolidated sedimentary rocks (sandstone, shale and coal). Based on literature the hydraulic conductivity of this aquifer likely ranges between 10-3 and 1 m.day-16.
5.2.2 Saturated Zone - Fractured, bedrock aquifer
The host geology of the area consists of consolidated sediments of the Karoo Supergroup and consists mainly of sandstone, shale and coal beds of the Ecca Group. Groundwater movement is predominantly associated with secondary structures in this aquifer (fractures, faults, dykes, etc.). The average water level depth in the area ranges between 5 and 25mbgl. Borehole yields in the Vryheid Formation and Dwyka aquifers are generally low and can be expected to be less than 2 l/s. Groundwater quality in the area is also expected to be intermediate to excellent with EC values ranging from 34 to 57mS/m.6
Both the porosity8 and the hydraulic conductivity9 of the Ecca Group fractured aquifers are known to be low. The commonly expected values of porosity and permeability for the rock types present in the site area, are 0 – 30% (porosity) and 10-7 – 1 m.d-1 (hydraulic conductivity) respectively (Kruseman & de Ridder, 1994). Movement of groundwater in this aquifer will be preferential in secondary structures such as joints, faults and fractures.
Dolerite intrusions in the form of dykes and sills are often encountered in these aquifers. These intrusions can serve both as aquifers and aquifuges. Thick, unbroken dykes inhibit the flow of water perpendicular to the dykes, forming (leaky) compartments in most instances. In contrast, the baked and cracked contact zones is normally highly conductive parallel to the dykes and these effectively interconnect the strata of the sediments both vertically and horizontally into a single aquifer, though highly heterogeneous and anisotropic unit on the scale of mining. These structures thus tend to dominate the flow of groundwater in fractured aquifers. Unfortunately, their location and properties are rather unpredictable and expensive to define in sufficient detail. Their influence on the flow of groundwater is thus incorporated by using higher than usual flow parameters for the sedimentary rocks of the aquifer.
5 Haupt, C.J., (1995). An explanation of the 1:500 000 General Hydrogeological Map. Johannesburg 2526. DWAF. 6 Kruseman, G.P. and de Ridder N. A. (1994). Analysis and Evaluation of Pumping Test Data. Second Edition (Completely Revised).
Model Update Report for Welgelegen Colliery- October 2018 10 Geo Pollution Technologies – Gauteng (Pty) Ltd
5.3 Groundwater Levels
During the 2013 hydrocensus, 5 boreholes were available for groundwater level measurement. The groundwater levels varied between a minimum of 4.63 m and a maximum of 10.7 m below ground level (Table 3). The relationship, using the boreholes from the hydrocensus, is shown in Correlation Graph- Water Levels
1595 1590 1585 y = 0.9079x + 138.73 1580 R² = 0.9899 1575 1570 Static Water Level 1565 Linear (Static Water 1560 Level)
Static Water Static Level (mamsl) 1555 1550 1545 1550 1560 1570 1580 1590 1600 1610 Elevation (mamsl)
Figure 5 below.
This general relationship is useful to make a quick calculation of expected groundwater levels at selected elevations, or to calculate the depth of to the groundwater level (unsaturated zone):
Groundwater level = Elevation x gradient + intercept
Groundwater depth = Elevation – Calculated Groundwater Level
In general a good relationship should exist between topography and static groundwater level. This relationship can be used to distinguish between boreholes with water levels at rest, and boreholes with anomalous groundwater levels due to disturbances such as pumping or local hydrogeological heterogeneities.
However, due to the heterogeneity of the subsurface, these relationships should not be expected to hold everywhere under all circumstances, and deviations could thus be expected.
Model Update Report for Welgelegen Colliery- October 2018 11 Geo Pollution Technologies – Gauteng (Pty) Ltd
Table 3: Available groundwater level statistics
Groundwater level statistics Number of boreholes available 5 Number of boreholes with 0 anomalous water levels Min water level (mbgl) 4.63 Max water level (mbgl) 10.7 Mean water level (mbgl) 6.7
Model Update Report for Welgelegen Colliery- October 2018 12 Geo Pollution Technologies – Gauteng (Pty) Ltd
Correlation Graph- Water Levels
1595 1590 1585 y = 0.9079x + 138.73 1580 R² = 0.9899 1575 1570 Static Water Level 1565 Linear (Static Water 1560 Level)
Static Water Static Level (mamsl) 1555 1550 1545 1550 1560 1570 1580 1590 1600 1610 Elevation (mamsl)
Figure 5: Correlation Graph of topography vs available groundwater levels
Model Update Report for Welgelegen Colliery- October 2018 13 Geo Pollution Technologies – Gauteng (Pty) Ltd
Figure 6: Contoured water levels of the water table aquifer (unconfined aquifer)
Model Update Report for Welgelegen Colliery- October 2018 14 Geo Pollution Technologies – Gauteng (Pty) Ltd
5.4 Groundwater Quality
Water samples were collected from 1 borehole and 5 surface water points around the site during the latest monitoring event. The water results are compared with the maximum recommended concentrations for domestic use as defined by the SANS 241-1: 2015 target water quality limits. The SANS 241-1: 2015 standard is applicable to all water services institutions and sets numerical limits for specific determinants to provide the minimum assurance necessary that the drinking water is deemed to present an acceptable health risk for lifetime consumption. Colours of individual cells refer to the drinking water classification of the specific groundwater sample.
The results of the screening for groundwater are presented in Table 4 and discussed in the sections below:
5.4.1 Groundwater and surface water quality vs SANS standards • TDS, Sulphate, Manganese and Aluminium were found to be above the SANS 241 limits in the PCD sample. pH was also found to be outside the SANS limits in the PCD sample.
• Iron and aluminium were found to be above the SANS limits in SWUS.
• Sulphate was found to be above the SANS limits in SWMS.
• Manganese exceeds the SANS limits in the on-site in use borehole B1.
• The elevated concentrations of sulphate, manganese and iron on site are likely a result of the coal mining activities in the area.
5.4.2 Spatial analysis of groundwater and surface water quality
The pie diagrams (Figure 7) show both the individual ions present in a water sample and the total ion concentrations in meq/ℓ or mg/ℓ. The scale for the radius of the circle represents the total ion concentrations, while the subdivisions represent the individual ions. It is very useful in making quick comparisons between waters from different sources and presents the data in a convenient manner for visual inspection. From the tables and figures the following can be deduced:
• The onsite borehole B1 has high proportions of HCO3 and Ca. • The upstream and downstream samples of the Wilge River and the upstream sample of the non-
perennial tributary of the Wilge River have high proportions of HCO3, SO4 and Na. • PCD and downstream sample of the non-perennial tributary of the Wilge River have high
proportions of HCO3, Ca and Mg. • Based on the piper diagram it can be seen that B1, WS1 and WS2 have a water type associated with fresh uncontaminated water while PCD, SWMS and SWUS have a water type associated with water contaminated by mining related activities.
Model Update Report for Welgelegen Colliery- October 2018 15 Geo Pollution Technologies – Gauteng (Pty) Ltd
Table 4: Water qualities compared to SANS 241-1:2015 guidelines for human consumption
SANS 241: Results 2015 Parameter Unit Risk Recommended WS 01 WS 02 PCD SWUS SWMS B-1 Limits 2018/06/19 2018/06/19 2018/06/19 2018/06/19 2018/06/19 2018/05/17 Physical & Aesthetic determinants Total Dissolved TDS mg/liter ≤ 1200 Aesthetic 196 270 2116 94 570 132 Solids pH at 250C pH units ≥ 5 to ≤9.7 Aesthetic 7.72 7.9 4.27 7.28 6.66 6.61 Chemical Determinants - Macro determinants
Nitrate as N NO3 mg/liter ≤ 11 Acute Health 0.1 0.1 0.1 0.11 0.1 0.1 Acute Health Acute Sulphate SO mg/liter ≤500; 38.7 65.2 1439 20.5 375 1.4 4 Health/Aesthetic Aesthetic ≤250 Fluoride F µg/liter ≤1500 Chronic Health 0.28 0.3 0.29 0.28 0.2 0.2 Chloride Cl mg/liter ≤ 300 Aesthetic 20 18.4 2.6 14.4 11.1 21.6 Sodium Na mg/liter ≤ 200 Aesthetic 26 31.4 18.9 18.6 21.1 10.3 Zinc Zn µg/liter ≤5000 Aesthetic Chemical Determinants - Micro determinants Acute Health ≤ Total Iron Fe mg/liter 2.0; Aesthetic Acute/Aesthetic 0.15 0.09 0.14 0.79 0.03 0.11 ≤0.3 Lead Pb µg/liter ≤ 10 Chronic Health Acute Health Total Mn mg/liter ≤0.4; Acute/Aesthetic 0.01 0.02 17.2 0.06 0.01 0.81 manganese Aesthetic ≤0.1 Aluminium Al µg/liter ≤ 300 Operational 40 70 1670 440 50 20
Model Update Report for Welgelegen Colliery- October 2018 16 Geo Pollution Technologies – Gauteng (Pty) Ltd
Figure 7: Pie diagrams for groundwater samples
Model Update Report for Welgelegen Colliery- October 2018 17 Geo Pollution Technologies – Gauteng (Pty) Ltd
Figure 8: Explanation of the hydrochemical facies in the Piper Diagram
Model Update Report for Welgelegen Colliery- October 2018 18 Geo Pollution Technologies – Gauteng (Pty) Ltd
Figure 9: Piper Diagram
Model Update Report for Welgelegen Colliery- October 2018 19 Geo Pollution Technologies – Gauteng (Pty) Ltd
6 AQUIFER CHARACTERISATION
The term aquifer refers to a strata or group of interconnected strata comprising of saturated earth material capable of conducting groundwater and of yielding usable quantities of groundwater to boreholes and /or springs (Vegter, 1994). In the light of South Africa’s limited water resources it is important to discuss the aquifer sensitivity in terms of the boundaries of the aquifer, its vulnerability, classification and finally protection classification, as this will help to provide a framework in the groundwater management process.
6.1 Aquifer Vulnerability
Aquifer vulnerability assessment indicates the tendency or likelihood for contamination to reach a specified position in the groundwater system after introduction at some location above the uppermost aquifer. Stated in another way, it is a measure of the degree of insulation that the natural and manmade factors provide to keep contamination away from groundwater.
• Vulnerability is high if natural factors provide little protection to shield groundwater from contaminating activities at the land surface.
• Vulnerability is low if natural factors provide relatively good protection and if there is little likelihood that contaminating activities will result in groundwater degradation.
The following factors have an effect on groundwater vulnerability:
• Depth to groundwater: Indicates the distance and time required for pollutants to move through the unsaturated zone to the aquifer.
• Recharge: The primary source of groundwater is precipitation, which aids the movement of a pollutant to the aquifer.
• Aquifer media: The rock matrices and fractures which serve as water bearing units.
• Soil media: The soil media (consisting of the upper portion of the vadose zone) affects the rate at which the pollutants migrate to groundwater.
• Topography: Indicates whether pollutants will run off or remain on the surface allowing for infiltration to groundwater to occur.
• Impact of the vadose zone: The part of the geological profile beneath the earth’s surface and above the first principal water-bearing aquifer. The vadose zone can retard the progress of the contaminants.
The Groundwater Decision Tool (GDT) was used to quantify the vulnerability of the aquifer underlying the site using the below assumptions.
• Depth to groundwater below the site was estimated from water levels measured during the 2013 hydrocensus inferred to be at mean of ~6.7 mbgl.
• Groundwater recharge of ~32 mm/a (4% recharge),
• Sandy clay loam soil vadose zone
• Gradient of 1% were assumed and used in the estimation.
The aquifer vulnerability for a contaminant released from surface to a specified position in the groundwater system after introduction at some location above the uppermost aquifer was determined using the criteria described below and assuming a worst case scenario:
Model Update Report for Welgelegen Colliery- October 2018 20 Geo Pollution Technologies – Gauteng (Pty) Ltd
• Highly vulnerable (> 60), the natural factors provide little protection to shield groundwater from contaminating activities at the land surface.
• Medium Vulnerable = 30 to 60%, the natural factors provide some protection to shield groundwater from contaminating activities at the land surface, however based on the contaminant toxicity mitigation measures will be required to prevent any surface contamination from reaching the groundwater table.
• Low Vulnerability (< 30 %), natural factors provide relatively good protection and if there is little likelihood that contaminating activities will result in groundwater degradation
• The GDT calculated a vulnerability value of 55%, which is medium.
6.2 Aquifer Classification
The aquifer(s) underlying the subject area were classified in accordance with “A South African Aquifer System Management Classification, December 1995.”
The main aquifers underlying the area were classified in accordance with the Aquifer System Management Classification document7. The aquifers were classified by using the following definitions:
• Sole Aquifer System: An aquifer which is used to supply 50% or more of domestic water for a given area, and for which there is no reasonably available alternative sources should the aquifer be impacted upon or depleted. Aquifer yields and natural water quality are immaterial.
• Major Aquifer System: Highly permeable formations, usually with a known or probable presence of significant fracturing. They may be highly productive and able to support large abstractions for public supply and other purposes. Water quality is generally very good (Electrical Conductivity of less than 150 mS/m).
• Minor Aquifer System: These can be fractured or potentially fractured rocks which do not have a high primary permeability, or other formations of variable permeability. Aquifer extent may be limited and water quality variable. Although these aquifers seldom produce large quantities of water, they are important for local supplies and in supplying base flow for rivers.
• Non-Aquifer System: These are formations with negligible permeability that are regarded as not containing groundwater in exploitable quantities. Water quality may also be such that it renders the aquifer unusable. However, groundwater flow through such rocks, although imperceptible, does take place, and needs to be considered when assessing the risk associated with persistent pollutants.
Based on information collected during the hydrocensus it can be concluded that the aquifer system in the study area can be classified as a “Major Aquifer System”, based on the fact that the local population is dependent on groundwater.
In order to achieve the Aquifer System Management and Second Variable Classifications, as well as the Groundwater Quality Management Index, a points scoring system as presented in Table 5 and Table 6 was used.
Table 5: Ratings – Aquifer System Management and Second Variable Classifications
7 Department of Water Affairs and Forestry & Water Research Commission (1995). A South African Aquifer System Management Classification. WRC Report No. KV77/95.
Model Update Report for Welgelegen Colliery- October 2018 21 Geo Pollution Technologies – Gauteng (Pty) Ltd
Aquifer System Management Classification Class Points Study area Sole Source Aquifer System: 6 Major Aquifer System: 4 4 Minor Aquifer System: 2 Non-Aquifer System: 0 Special Aquifer System: 0 – 6 Second Variable Classification (Weathering/Fracturing) Class Points Study area High: 3 Medium: 2 2 Low: 1
Table 6: Ratings - Groundwater Quality Management (GQM) Classification System
Aquifer System Management Classification Class Points Study area Sole Source Aquifer System: 6 Major Aquifer System: 4 4 Minor Aquifer System: 2 Non-Aquifer System: 0 Special Aquifer System: 0 – 6 Aquifer Vulnerability Classification Class Points Study area High: 3 Medium: 2 2 Low: 1
As part of the aquifer classification, a Groundwater Quality Management (GQM) Index is used to define the level of groundwater protection required. The GQM Index is obtained by multiplying the rating of the aquifer system management and the aquifer vulnerability. The GQM index for the study area is presented in Table 7.
The vulnerability, or the tendency or likelihood for contamination to reach a specified position in the groundwater system after introduction at some location above the uppermost aquifer, in terms of the above, is classified as medium.
The level of groundwater protection based on the Groundwater Quality Management Classification:
GQM Index = Aquifer System Management x Aquifer Vulnerability = 4 x 2 = 8
Model Update Report for Welgelegen Colliery- October 2018 22 Geo Pollution Technologies – Gauteng (Pty) Ltd
Table 7: GQM Index for the Study Area
GQM Index Level of Protection Study Area <1 Limited 1 – 3 Low Level 3 – 6 Medium Level 6 – 10 High Level 8 >10 Strictly Non-Degradation
6.3 Aquifer Protection Classification
A Groundwater Quality Management Index of 8 was estimated for the study area from the ratings for the Aquifer System Management Classification. According to this estimate a medium level groundwater protection is required for the aquifer. Reasonable and sound groundwater protection measures based on the modelling will therefore be recommended to ensure that no cumulative pollution affects the aquifer, even in the long term.
DWA’s water quality management objectives are to protect human health and the environment. Therefore, the significance of this aquifer classification is that measures must be taken to limit the risk to the following environments.
• The protection of the underlying aquifer.
• The Wilge River and its tributaries as well as the wetlands around the mining area.
Model Update Report for Welgelegen Colliery- October 2018 23 Geo Pollution Technologies – Gauteng (Pty) Ltd
7 GEOCHEMICAL ASSESSMENT
GPT collected 3 geochemical samples at the Welgelegen Colliery on the 16th of October 2018. Two samples were collected at discard positions and one overburden sample was collected in pit.
Table 8: Location of geochemical samples
ID LONGITUDE LATITUDE Sample Description Photo
WGLDiscard1 28.838778 -26.128414 Fresh discard after processing
WGLDiscard2 28.852825 -26.130809 Older discard on discard dump
WGLDiscard3 28.848969 -26.125074 Over burden material
The samples were sent to SANAS accredited laboratory (UIS Organic Laboratory (Pty) Ltd) for analysis. All three samples were analysed by quantitative X-ray diffraction, ICP-MS and a leach test. The results of the analyses can be seen in Table 9, Table 10, Table 11 and Table 12 below:
Model Update Report for Welgelegen Colliery- October 2018 24 Geo Pollution Technologies – Gauteng (Pty) Ltd
Table 9: XRD data generated on the three coal discard samples collected.
Table 10: Trace element analyses on discard material
Table 11: Major element analyses on discard material
Table 12: Major and trace element analyses on leachate from discard material
A geochemical assessment was compiled by Aquatox Consulting (Pty) Ltd based on the results of the analyses above. The report can be found in Appendix II. In summary the report indicates the following regarding the geochemical samples:
The main characteristic of a hypothetical coal mine has been sketched using the chemical analyses of discard material, XRD analyses of those sample, as well as the leachate emanating from these rocks under a controlled leachate test. The result stipulate that rocks stored above the water table (saturated zone) would more prone to the generation of AMD, compared to rocks underneath the water table (saturated zone).
8 GROUNDWATER FLOW AND TRANSPORT MODELLING
The numerical groundwater flow model is constructed and simulated to aid in decision making processes and environmental management.
The groundwater regime of the study area is highly heterogeneous due to complex faulting and intrusions, which ultimately influence the groundwater flow patterns. Constructing a groundwater flow model with all the detail is close to impossible; however, assumptions are made based on data
Model Update Report for Welgelegen Colliery- October 2018 25 Geo Pollution Technologies – Gauteng (Pty) Ltd gathered in the field and used to simulate different scenarios to conclude with management protocol.
Therefore the purpose of the numerical model is to develop a tool than can be used to assess the impact of the colliery during the operational phase taking into account existing operations. Together with this, simulate the impacts associated with potential pollution sources.
8.1 Software Model Choice
The finite difference numerical model was created using AquaVeo’s Groundwater Modelling System (GMS10) as Graphical User Interface (GUI) for the well-established Modflow and MT3DMS numerical codes.
MODFLOW is a 3D, cell-centred, finite difference, saturated flow model developed by the United States Geological Survey. MODFLOW can perform both steady state and transient analyses and has a wide variety of boundary conditions and input options. It was developed by McDonald and Harbaugh of the US Geological Survey in 1984 and underwent eight overall updates since. The latest update (Modflow-NWT) incorporates several improvements extending its capabilities considerably, the most important being the introduction of the Newton formulation of Modflow. This dramatically improved the handling of dry cells that has been a problematic issue in Modflow in the past.
MT3DMS is a 3-D model for the simulation of advection, dispersion, and chemical reactions of dissolved constituents in groundwater systems. MT3DMS uses a modular structure similar to the structure utilized by MODFLOW, and is used in conjunction with MODFLOW in a two-step flow and transport simulation. Heads are computed by MODFLOW during the flow simulation and utilized by MT3DMS as the flow field for the transport portion of the simulation.
8.2 Model Set-up and Boundaries
Boundaries were chosen to include the area where the groundwater pollution plume could reasonably be expected to spread and simultaneously be far enough removed from site boundaries not to be affected by groundwater abstraction. These boundaries are described in Table 13.
These boundaries resulted in an area of about 5 to 13 km around the current and proposed mining aeeas, which is considered far enough for the expected groundwater effects not to be influenced by boundaries.
8.3 Groundwater Elevation and Gradient
The calibrated static water levels as modelled have been contoured (Figure 6). Groundwater flow direction should be perpendicular to these contours and inversely proportional to the distance between contours. As can be expected, the groundwater flow is mainly from topographical high to low areas, eventually draining to the local streams.
8.4 Geometric Structure of the Model
The geometric structure of the model is discussed in Appendix G, with only the conceptual model input and fixed aquifer parameters discussed below.
Model Update Report for Welgelegen Colliery- October 2018 26 Geo Pollution Technologies – Gauteng (Pty) Ltd
8.5 Groundwater source and sinks
Although the most relevant aquifer parameters are optimised by the calibration of the model, many parameters are calculated and/or judged by conventional means. The fixed assumptions and input parameters were used for the numerical model of this area.
Table 13: Input parameters to the numerical flow model
Model Parameter Value Unit Reason Recharge to the 0.0001 m/d Calculated aquifer Recharge to the backfilled opencast 0.0004 m/d Hodgson and Krantz (1998) mine Evapotranspiration 0.004 m/d Calculated Existing boundary conditions present at the Topographic water Boundaries - site that would potentially include divides modelled impacts Refinement 20 m Based on the scale of the mining area Cell Grid dimensions 400 x 450 Product of the grid refinement count Hydraulic 0.115 m/d Calibrated conductivity Hydraulic anisotropy 10 - Anderson et al. (2015) (vertical) 5 declining to 3 Effective porosity with depth in each % Wang et al. (2009) layer Layers 4 Count Mining depth is 30m Longitudinal 50 m Schulze-Makuch (2005) dispersion Calculated as 10% of the difference Head error range 10 m between the maximum and minimum calculated head elevations
8.6 Conceptual model input
For the purpose of this study, the subsurface was envisaged to consist of the following hydrogeological units.
• The upper few meters below surface consist of completely weathered material. This layer is anticipated to have a reasonable high hydraulic conductivity, but in general unsaturated. However, a seasonal aquifer perched on the bedrock probably does form in this layer, especially after high rainfall events. Flow in this perched aquifer is expected to follow the surface contours closely and emerge as fountains or seepage at lower elevations.
• The next few tens of meters are weathered, highly fractured shale/sandstone bedrock with a low hydraulic conductivity. The permanent groundwater level resides in this unit and is about 1
Model Update Report for Welgelegen Colliery- October 2018 27 Geo Pollution Technologies – Gauteng (Pty) Ltd
to 10 meters below ground level. The groundwater flow direction in this unit is influenced by regional topography and for the site flow would be in general from high lying areas to the Wilge River.
• Below a few tens of meters the fracturing of the aquifer is less frequent and fractures less significant due to increased pressure. This results in an aquifer of lower hydraulic conductivity and very slow groundwater flow velocities. The flow direction is expected to be mostly northerly. This trend was confirmed by modelling.
8.7 Calibration of the Numerical Model
Water level and quality data obtained during the hydrocensus was used to calibrate the steady state numerical groundwater flow model. The results obtained during the steady state scenarios were used as initial conditions to simulate dewatering and contaminant transport impacts. A good fit was obtained for the measured groundwater levels and concentrations (Figure 10 to Figure 11).
All other parameters were unchanged, with values as listed in the paragraphs above. The calibration error statistics can be seen in Table 15. The mean head error was 0.22 metre, which can be regarded as good for the purpose.
Model Update Report for Welgelegen Colliery- October 2018 28 Geo Pollution Technologies – Gauteng (Pty) Ltd
Table 14: Optimal Calibrated Aquifer Parameters
Layer thickness Porosity Hydraulic conductivity Aquifer Model layer (m) (%) (m/d) Regolith (top soil Layer 1 5 0.3 1.0 +softs) Shallow Highly Layer 2 40 0.05 0.115 Fractured Aquifer Deeper Moderately Layer 3 50 0.04 0.0115 Fractured Aquifer Deepest Slightly Layer 4 50 0.03 0.00115 Fractured Aquifer
Table 15: Calibration Statistics
Description Value Mean Residual (Head) 0.22 Mean Absolute Residual (Head) 5.62 Root Mean Squared Residual (Head) 6.80
Model Update Report for Welgelegen Colliery- October 2018 29 Geo Pollution Technologies – Gauteng (Pty) Ltd
Computed vs. Observed Groundwater Levels Head (mamsl)
1580
1560
1540 Computed
1520
1500 1500 1520 1540 1560 1580 Observed
Figure 10: Water level Calibration Graph
Model Update Report for Welgelegen Colliery- October 2018 30 Geo Pollution Technologies – Gauteng (Pty) Ltd
8.8 Model Runs
8.8.1 Pre-Mining
This model represents the pre-mining scenario and is used for calibration purposes. The model is representative of steady-state natural conditions prior to the application of stresses to the aquifer and provides a baseline from which all following calculations are performed. All required hydraulic parameters are defined and calibrated in this model as a simplified mathematical representation of the hydrogeological scenario on and around the site.
8.8.2 During-Mining
This model represents the groundwater situation during operation of the mine. For the purposes of this model a worst-case scenario was assumed, namely that all the opencasts will be dewatered during the mining period. A drain was thus imposed under the mining area at mining depth. The modelling included the following transport and dewatering scenarios:
Dewatering
• Current eastern opencasts
• Planned western opencasts
Transport
• Current eastern opencasts
• Planned western opencasts • Plant area
• Return Water Dams
The numerical groundwater flow model indicates the associated flow directions and velocities and simulated inflow rates towards the mining activities.
8.8.3 Post-Mining
This models the post-mining scenario, assuming that the most likely recharge over the rehabilitated opencasts will be 0.0004 m/d. This amounts to a recharge of about 20% of rainfall, which is probably a realistic if not worst case scenario8. The modelling included the following transport and dewatering scenarios:
Discharge
• Current eastern opencasts
• Planned western opencasts
Transport
• Current eastern opencasts
• Planned western opencasts
8 Grobbelaar, R et al: Long-Term Impact of Intermine Flow from Collieries in the Mpumalanga Coalfields, Sept 2004. Institute for Groundwater Studies, University of the Free State, Bloemfontein RSA.
Model Update Report for Welgelegen Colliery- October 2018 31 Geo Pollution Technologies – Gauteng (Pty) Ltd
• Plant area
• Return Water Dams
Model Update Report for Welgelegen Colliery- October 2018 32 Geo Pollution Technologies – Gauteng (Pty) Ltd
9 HYDROGEOLOGICAL IMPACTS
It is the aim of this chapter to assess the likely hydrogeological impact that the mining might have on the receiving environment. The typical operational stages that will be considered in this section are:
• Operational Phase: The conditions expected to prevail during the operation of the site.
• Decommissioning Phase: The closing of operations as well as site clean-up and rehabilitation.
• Post-mining Phase: This relates to the steady-state conditions following site-closure. A period will be considered after which it is assumed that impacts will steadily decrease and the system will commence its return to the natural state
9.1 Operational Phase Impacts
The operational phase is interpreted as the active mining of the two opencasts at the site. It is inevitable that these effects will impact on the groundwater regime. The potential impacts that will be considered are the groundwater quantity and quality. A summary of the potential impacts during operation can be seen in Table 16.
9.1.1 Impacts on groundwater quantity
During the operational phase, it is expected that the main impact on the groundwater environment will be de-watering of the surrounding aquifer. Water entering the mining areas will have to be pumped out to enable mining activities. This will cause a lowering in the groundwater table in- and adjacent to the mine.
The dewatering of the aquifer has been calculated for the opencasts using the calibrated numerical model as described above. A worst-case scenario has been modelled, assuming that all opencasts would be dewatered simultaneously. This will obviously not be the case, and the actual drawdown could thus be less. However, as the recovery of groundwater is expected to be very slow, it could well be that the first boxcut is still in an early stage of recovery. Thus, the worst case scenario could also be close to the actual scenario. The calculated drawdown of the worst case scenario is depicted in Figure 12 below, as contours of drawdown for the opencasts being dewatered simultaneously.
Despite the modelled predictions, it must again be stressed that structures of preferred groundwater flow have not been modelled. It is known by experience that dolerite will most likely transgress the area, but details are limited and not adequate to model this structure(s). If such a structure is dewatered, any boreholes drilled into the structure might be seriously affected. These effects cannot be predicted with the current knowledge, and can only be established through continuous groundwater level monitoring.
The computed total inflow into each mine, assuming that all areas in the mine are dewatered simultaneously, was calculated as tabled below in Table 16.
However, these figures are overestimations and probably reflect worst-case scenarios. The actual inflow will depend on the area being mined at any one moment in time. However, at the last cut, the inflow from the backfilled portion of the mine could be substantial and the above inflows can be approached.
It is important to view these numbers for the water make of the mine in relation to natural evaporation, as listed in the table. Illustrative volumes are included in the table as if the
Model Update Report for Welgelegen Colliery- October 2018 33 Geo Pollution Technologies – Gauteng (Pty) Ltd evaporation will take place over the whole opencast, for comparative purposes. As the whole opencast will not be open at any one time, this is obviously an overestimate. Nevertheless, it is illustrative that evaporation can contribute considerably to the removal of groundwater seepage into the opencast.
Furthermore, it should be realised that evaporation is a seasonal effect. Direct recharge from rainfall will in turn add to these volumes. The amount of direct recharge will depend on the season as well as the mining layout and storm water management. It is suggested that this is calculated as part of the surface water study.
It must be cautioned that these calculations have been performed using simplified assumptions of homogeneous aquifer conditions. The reality could deviate substantially from this and the model should thus be updated as more information becomes available.
9.1.2 Impacts on surface water
Although surface water as such is not part of this study, the impact of the mining on streams in the area can be estimated qualitatively from the model in so far as the groundwater component (base flow) of the stream is concerned. Such an impact assessment will not include possible surface runoff influences caused by mining, but merely addresses the base flow component due to gaining (or losing) of groundwater by the stream.
It can be deduced from the calculated figures that the cumulative groundwater drawdown at the streams close to the mine could be impacted (Table 16). In particular, the north-western tributary of the Wilge River is undercut by the cone of depression and the cumulative drawdown could affect the stream’s baseflow. However, these local streams are mostly underlain by a clay layer, isolating the stream from the groundwater. These streams are also non-perennial and serve as storm water drains during high rainfall events. The impact on the flow of the steam is thus not predicted to be impacted.
9.1.3 Impacts on groundwater quality
The flow in the aquifer will be directed towards the mine at this stage and very little groundwater pollution is thus expected.
Model Update Report for Welgelegen Colliery- October 2018 34 Geo Pollution Technologies – Gauteng (Pty) Ltd
Table 16: Summary of potential impacts during operation – dewatering
Mining Cone of depression from Estimated Inflow for the Evaporation Potential Impacted Expected Water Area (ha) Area edge of pit (m) Total Area (m3/day) (m3/day) Receptor Level Decline (m)
Western North-western 110 800 1 000 4 400 10 Opencast Tributary Eastern 70 800 500 2 800 Eastern Tributary 5 Opencast
Model Update Report for Welgelegen Colliery- October 2018 35 Geo Pollution Technologies – Gauteng (Pty) Ltd
9.1.4 Groundwater management
9.1.4.1 General
• Identify and where possible, maximise areas of the mine that will result in clean storm water runoff (for example open veld areas) as well as infrastructure associated with the mine (for example office areas) and ensure that runoff from these areas is routed directly to natural watercourses and not contained or contaminated.
• Ensure that clean storm water is only contained if the volume of the runoff poses a risk, if the water cannot be discharged to watercourses by gravitation, for attenuation purposes, or when the clean area is small and located within a large dirty area. This contained clean water should then be released into natural watercourses under controlled conditions.
• Ensure the minimisation of contaminated areas, reuse of dirty water wherever possible and planning to ensure that clean areas are not lost to the catchment unnecessarily.
• Ensure that seepage losses from storage facilities (such as polluted dams) are minimised and overflows are prevented.
• Ensure that all possible sources of dirty water have been identified and that appropriate collection and containment systems have been implemented and that these do not result in further unnecessary water quality deterioration.
• Ensure that less polluted water or that: moderately polluted water is not further polluted. Where possible less and more polluted water should be separated. This will assist in the reuse water strategy and improve possibilities for reuse based on different water quality requirements by different mine water uses.
• Where contaminants are transported along construction roads, emergency containment and mitigation measures must be developed to minimize impacts should accidental spillages occur along the transport routes.
• Store all potential sources of contamination in secure facilities with appropriate Storm Water management systems in place to ensure that contaminants are not released to the water resource through Storm Water runoff.
• Separate and collect all storm water that has a quality potentially poorer than the water quality specified and negotiated for the specific catchment into dirty water storage facilities for reuse within the mining operations.
• Ensure that all storm water structures that are designed to keep dirty and clean water separate can accommodate a defined precipitation event. (The magnitude of the precipitation event used in such an objective statement must, as a minimum, adhere to the relevant legal requirements.)
• Route all clean storm water directly to natural watercourses without increasing the risk of a negative impact on safety and infrastructure, e.g. loss of life or damage to property due to an increase in the peak runoff flow.
• Ensure that the maximum volume of clean water runoff is diverted directly to watercourses and the minimum amount of storm water reports to the pit floor of an open cast mine.
• Develop and implement proper environmental management and auditing systems to ensure that pollution prevention and impact minimisation plans and measures developed in the design and feasibility stages are fully implemented.
Model Update Report for Welgelegen Colliery- October 2018 36 Geo Pollution Technologies – Gauteng (Pty) Ltd
• The size of unrehabilitated areas (pit, spoils, unvegetated areas) that produce contaminated runoff should be minimised.
• Rehabilitation should be planned to promote free drainage and to minimise or eliminate ponding of storm water. On-going rehabilitation as mining operations progress is required.
• The clean and dirty water flow areas on a mine site should be identified.
• Every effort should be made to maximise the clean area and minimise the dirty area when locating the diversion berms, channels and dams. In the case of a new mine, the maximisation of the clean areas should have an influence in overall mine planning and the location of the mine infrastructure
• The mine planning should consider concurrent rehabilitation of mine workings and waste management facilities, to maximise the areas of clean runoff that can be discharged to the natural watercourses
9.1.4.2 Waste rock deposits and pollution control dams
• Monitoring of water storage facilities, particularly pollution control dams, is imperative to manage the risk of spillage from the dams. Stage-storage (elevation-capacity) curves are useful tools to monitor the remaining capacity within a water storage facility.
• Prevent the erosion or leaching of materials from any residue deposit or stockpile from any area and contain material or substances so eroded or leached in such area by providing suitable barrier dams, evaporation dams or any other effective measures to prevent this material or substance from entering and polluting any water resources.
• Water quantity and quality data should be collected on a regular, ongoing basis during mine operations. These data will be used to recalibrate and update the mine water management model, to prepare monitoring and audit reports, to report to the regulatory authorities against the requirements of the IWMP and other authorisations and as feedback to stakeholders in the catchment, perhaps via the CMA.
• Water that has been in contact with residue, and must therefore be considered polluted, must be kept within the confines of the MRD until evaporated, treated to rendered acceptable for release, or re-used in some other way.
• All water that falls within the catchment area of the MRD must be retained within that area. For most MRDs the catchment can be divided into component catchments, as follows: o The top area of the MRD together with any return water storage dams which have been connected to the top area of the MRD by means of an outfall penstock, and o The faces of the MRD together with the catchment paddocks provided to receive run-off from the faces and any additional catchment dams associated with the faces and catchment paddocks.
• The design, operation and closure of MRDs should incorporate consideration of the risk of changes in the mining and plant operations, and hence the mine water balance, through the life cycle of the mine.
• A system of storm water drains must be designed and constructed to ensure that all water that falls outside the area of the MRD is diverted clear of the deposit. Provision must be made for the maximum precipitation to be expected over a period of 24 hours with a probability of once in one hundred years. A freeboard of at least 0.5 m must be provided throughout the system above the predicted maximum water level. This requirement applies to all MRDs, both fine and coarse-grained MRDs.
Model Update Report for Welgelegen Colliery- October 2018 37 Geo Pollution Technologies – Gauteng (Pty) Ltd
• Ensure that the water use practices on and around the MRD do not result in unnecessary water quality deterioration, e.g. use of the return water dam for storage of poorer quality water.
Should the above be insufficient to capture polluted surface and groundwater moving towards the tributaries of the Wilge River an interception trench can be designed as follows:
• The depth of the trench should be at least 4 mbgl (or 2 m below the groundwater level) to intercept polluted seepage that resulted from the WRD;
• The design of the trench gradient must be such that the water is free-flowing without eroding the channel;
• The water from the trench must be captured, retained and managed within the mine water systems.
9.1.4.3 Opencast pits
• Mining should aim to remove as much of the coal seam (acid generating material) as possible.
• Should any boreholes decrease in yield as a result of the mines dewatering activities the mine should supply the owners with a volume of water as agreed upon between the parties involved.
• The capacity to rapidly pump water out of the pit into storage dams should be maintained. This will assist in minimising water quality deterioration due to long-term retention of storm water in contact with materials that may cause water quality deterioration.
• Berms should be constructed around the opencast pits to minimise the flow of any surface water or floodwater into mine workings. These berms should be constructed to allow free drainage away from the pits.
• Separate acid generating material and non-acid generating material, as characterised by geochemical sampling and analyses, should be separated during mining
• Concurrent rehabilitation should take place during the operational phase, where applicable, to: o Meet the post-mining topography requirements. o Minimise the post-closure water management requirements, by maximising free- draining areas and minimising contamination of clean water. o The above water management principles should play a key and decisive role when evaluating and deciding on rehabilitation and closure strategies. o Additionally, adding lime to backfill material could be considered to minimise the generation of acidity.
• Water quantity and quality data should be collected on a regular, ongoing basis during mine operations. These data will be used to recalibrate and update the mine water management model, to prepare monitoring and audit reports, to report to the regulatory authorities against the requirements of the IWMP and other authorisations and as feedback to stakeholders in the catchment, perhaps via the CMA. See the Monitoring Network section.
• If excessive groundwater recharge and rainfall is encountered other than the predicted volumes the water could be managed as follows: o Manage in-pit seepage and rainfall through a collection and storage system. Water stored in pit should be utilised locally for dust suppression, as far as possible. Excess pit water should be pumped to surface to be incorporated into the mine water balance, o Maximise the abstraction and discharge of clean groundwater ahead of the pit development, through installation of dewatering boreholes surrounding the pit.
Model Update Report for Welgelegen Colliery- October 2018 38 Geo Pollution Technologies – Gauteng (Pty) Ltd
Please note that further investigation will be required for the above especially the siting and pumping rate of the dewatering boreholes.
9.2 Decommissioning and Post-closure Phase Impacts
During this phase it is assumed that dewatering of the opencasts will be ceased, and it will be allowed to flood. The groundwater regime will return to a state of equilibrium once mining has stopped and the removal of water from the mining void has been discontinued.
The rise in groundwater level is predicted to be relatively slow and the water levels are expected to recover only in about 20 - 30 years. The slow recovery is ascribed to the low hydraulic conductivity of the surrounding bedrock. The following possible impacts were identified at this stage:
• Following closure of the mine, the groundwater level will rise to an equilibrium that will differ from the pre-mining level due to the disturbance of the bedrock. However, this change is likely to be minimal.
• Groundwater within the mined areas is expected to deteriorate due to chemical interactions between the geological material and the groundwater. The resulting groundwater pollution plume is expected to commence with downstream movement.
• Continued groundwater contamination is likely to be released from the plant facility if it is not cleaned up.
A summary of the potential impacts during the closure of the mine is shown in Table 18.
9.2.1 Impacts on groundwater quantity
After closure, the water table will rise in the mine to reinstate equilibrium with the surrounding groundwater systems. However, the mined areas will have a large hydraulic conductivity compared to the pre-mining situation.
9.2.1.1 Rebound and Potential Decant
Following the closure of the opencasts and the cessation of the dewatering it is assumed to lead to groundwater rebound. This estimated rebound time in years for each individual opencast after cessation of pumping is shown in Table 18.
After rebound has reached equilibrium or water in the pit equal to surrounding host rock, decant has the potential to occur due to excessive rainfall and surface water run-off water entering the pit. The percentage of the rainfall/run-off that is recharged into the rehabilitated opencast and potential decant depends on:
• The slope of the rehabilitated pit and its direct surroundings. • The thickness and composition of the topsoil. i.e. clay content and compaction.
• The vegetation of the rehabilitation and its direct surroundings.
• The amount rainfall and intensity of the rainfall events.
• The size of the ramps and the final voids.
No decant is predicted by the numerical model, although groundwater will rise to very close to ground level in the north-eastern corner of the western opencast, and the south-western corner of the eastern opencast.
Model Update Report for Welgelegen Colliery- October 2018 39 Geo Pollution Technologies – Gauteng (Pty) Ltd
Table 17: Water recharge-characteristics for opencast mining in the Mpumalanga area (Hodgson and Krantz, 1998)9
Water into opencast Suggested Mean value Water Source (% rainfall) (% rainfall) Rain onto ramps and voids 20–100 70 Rain onto not rehabilitated spoils 30–80 60 Rain onto levelled spoils (run-off) 3-7 5 Rain onto levelled spoils (Seepage) 15-30 20 Rain onto rehabilitated spoils (run-off) 5-15 10 Rain onto rehabilitated spoils (seepage) 5-10 8 (% of total pit water) (% of total pit water) Surface run-off from pit surroundings 5-15 6 Groundwater seepage 2-15 10
9.2.2 Impacts on groundwater quality
Once the normal groundwater flow conditions have been re-instated, polluted water could potentially migrate away from the mining areas.
9.2.2.1 Spread of pollution
As some discards and exposed reactive mineral surfaces will remain in the mine, this outflow could be contaminated as a result of mine drainage. As sulphate is normally a significant solute in drainage from mines, sulphate concentration from the mine has been modelled as a conservative (non-reacting) indicator of mine drainage pollution.
A starting concentration of 2 000 mg/litre has been assumed as a worst case scenario should waste material be deposited in the pits above the groundwater level. For the scenario where waste is stored below the water level (as is done currently at the mine), a starting concentration of 1 000 mg/l, decreasing annually by 5%, has been assumed. The rational is that waste has been exposed to the atmosphere for a while before deposition and some oxidation has inevitably take place. This will result in a reasonable high initial concentration, estimated at 50% of the above water scenario, followed by a rapid solution and dilution of sulphates as represented by the 5% annual reduction in concentration.
The migration of contaminated water from the mining area has been modelled as described, and the results are presented in Figure 14, Figure 15 and Figure 16 in terms of the extent of the pollution plume 10, 25, 50 and 100 years after the operations have ceased. As stated previously, the results must be viewed with caution as a homogeneous aquifer has been assumed. Heterogeneities in the aquifer are unknown and the effect of this cannot be predicted. Furthermore, no chemical interaction of the leachate with the minerals in the surrounding bedrock has been assumed. As there must be some interaction and retardation of the plume, this calculation will represent a worst-case scenario.
9 Hodgson, F.D.I.; Krantz, R.M., (1998), "Groundwater Quality Deterioration in the Olifants River Catchment above the Loskop Dam with Specialised Investigations in the Witbank Dam Sub-Catchment", WRC Report no. 291/1/98.
Model Update Report for Welgelegen Colliery- October 2018 40 Geo Pollution Technologies – Gauteng (Pty) Ltd
Within the limitations of the abovementioned assumptions, impacts have been estimated as listed in Table 18. The following needs to be pointed out:
• Although no decant is predicted by the model, the groundwater level is predicted to rise to very close to surface in the north-east of the western opencast and in the south-west of the eastern opencast. Should there be occasional seepage to surface, it will be to these areas.
• Plume movement from the opencasts will be mostly towards the streams at a low speed of about 10 m/y maximum, depending mainly on slope of the groundwater table.
• The contours of plume movement indicate that contamination might reach the Wilge River and its northwester tributary in about 30 to 50 years in the worst case scenario. However, the contamination is unlikely to have a lasting effect on the water courses as they are normally lined with a natural clay layer and thus poorly connected to the groundwater.
• Furthermore, the streams are also normally dry and only carry water after rainfall events. This mass of water will wash down any contaminated seepage and dilute it to unmeasurable concentrations.
• However, if the mine discard is placed underneath the groundwater level (as is being done right now), Figure 20 indicates that the sulphate reaching the water courses will be of low concentration.
• It is also noticeable that the contamination from the plant area will move eastwards and eventually flow into the defunct western opencast at low concentrations. No impact on any stream is thus anticipated resulting from the plant contamination.
Model Update Report for Welgelegen Colliery- October 2018 41 Geo Pollution Technologies – Gauteng (Pty) Ltd
Table 18: Summary of potential impacts post operations
Estimated increase Area Potential impacted in concentrations Rebound time Potential decant Mining Area Potential decant area (ha) receptor during closure (Years) (Yes/No) (mg/ℓ)
North-western Western Opencast 110 1 000 20 No N/A Tributary
Eastern Opencast 70 Eastern Tributary 2 000 30 No N/A
Model Update Report for Welgelegen Colliery- October 2018 42 Geo Pollution Technologies – Gauteng (Pty) Ltd
9.2.3 Cumulative effects
The cumulative pollution impacts of all current and historic mining in addition to the planned opencasts could not be calculated as any data on surrounding mines is not available. However it is highly recommended that a regional study be undertaken to quantify impacts on at least a quaternary scale or a data sharing agreement should be reached with neighbouring mines.
9.2.4 Groundwater management
9.2.4.1 Waste rock deposits
• Update the numerical and geochemical model against monitored data
• After proper geochemical investigation the ARD can be dealt with as follows; o Cover and capping research studies and design to reduce water and oxygen reactions o Use as waste backfill in open pits or underground o Neutralisation (e.g. lime) and treatment (stimulation of sulphate reducing bacteria) o Segregation/isolation/encapsulation o Passive leachate management and treatment
• Polluted groundwater can be treated as follows: o Reduce hydraulic head by water shedding o Integrate capture store-release systems o Utilise evapotranspiration o Cap and cover with capillary break o Drainage diversions o Neutralisation and detoxification of tails seepage o Wetland filtration
9.2.4.2 Opencast pits
The post-closure groundwater management of the opencast should be done in two phases:
• Phase 1: Immediately after closure
• Phase 2: After Rapid Flooding
Please note that the numerical and geochemical model needs to be updated against monitored data during the post-closure phase.
Phase 1: Immediately after closure
During mining the acid generating material and non-acid generating material should have been separated.
• The acid producing material should be placed as low in the pits as possible, followed by the non-acid generating material.
• Rapid flooding should be done by diverting storm water channels and pumping of available groundwater into the pit until the acid producing material is inundated by the water.
Model Update Report for Welgelegen Colliery- October 2018 43 Geo Pollution Technologies – Gauteng (Pty) Ltd
Phase 2: After Rapid Flooding
After the acid producing material is inundated by the water:
• The final backfilled opencast topography should be engineered such that runoff is directed away from the opencast areas.
• The final layer (just below the topsoil cover) should be as clayey as possible and compacted if feasible, to reduce recharge to the opencasts.
• Natural berms should then be constructed to allow free drainage of surface water around the rehabilitated pit.
9.2.4.3 Assumptions and Limitations
The modelling was done within the limitations of the scope of work of this study and the amount of data available. Although all efforts have been made to base the model on sound assumptions and has been calibrated to observed data, the results obtained from this exercise should be considered in accordance with the assumptions made. Especially the assumption that a fractured aquifer will behave as a homogeneous porous medium can lead to error. However, on a large enough scale (bigger than the REV, Representative Elemental Volume) this assumption should hold reasonably well.
Model Update Report for Welgelegen Colliery- October 2018 44 Geo Pollution Technologies – Gauteng (Pty) Ltd
Figure 11: Calibration of the numerical model (5 m head interval)
Model Update Report for Welgelegen Colliery- October 2018 45 Geo Pollution Technologies – Gauteng (Pty) Ltd
Figure 12: Cone of depression during mining
Model Update Report for Welgelegen Colliery- October 2018 46 Geo Pollution Technologies – Gauteng (Pty) Ltd
Rebound of Groundwater Levels 1535
1530
1525
1520
Groundwater1515Level (mamsl)
0 10000 20000 30000 Time (days after mining)
Figure 13: Rebound stage curve
Model Update Report for Welgelegen Colliery- October 2018 47 Geo Pollution Technologies – Gauteng (Pty) Ltd
Figure 14: Predicted spread of pollution post-closure of mining – discard above groundwater
Model Update Report for Welgelegen Colliery- October 2018 48 Geo Pollution Technologies – Gauteng (Pty) Ltd
Figure 15: Predicted spread of pollution post-closure of mining – discard below groundwater
Model Update Report for Welgelegen Colliery- October 2018 49 Geo Pollution Technologies – Gauteng (Pty) Ltd
Figure 16: Predicted spread of pollution post-closure of mining – plant area rehabilitated
Model Update Report for Welgelegen Colliery- October 2018 50 Geo Pollution Technologies – Gauteng (Pty) Ltd
10 IMPACT ON THE WETLANDS
10.1 Methodology
Interflow, which is normally not considered as part of the permanent groundwater system, could also be an important contributor of groundwater feed to the wetlands. Interflow is defined as that component of groundwater flow that perched on low hydraulic conductive. Any low conductance stratum in the subsurface can serve as a perching medium, but the most common of these are clay layers, calcrete and ferricrete banks, and finally also the bedrock. This part of the subsurface water flow is less regularly modelled, as most groundwater models handle two distinct water tables with difficulty. This problem was simplified by modelling only the regolith (soil) layer on top of the bedrock, with the assumption that perching is on bedrock. The input to this 2D model was obtained from the calibrated 3D model, with the exception of the recharge to the layer. To allow perching, the recharge to the regolith layer has to be considerably higher than the seepage to the deeper perched aquifer. This will be described in the paragraph covering the conceptual site model.
10.2 Conceptual Model
The 2D interflow conceptual model is shown in . In the latter figure, the most important features to the perched aquifer are indicated. This includes a highly permeable regolith (soil or softs) layer, underlain by bedrock with much lower permeability. This contrast in permeability results in a higher volume of water infiltrating in the regolith, which cannot be absorbed by the bedrock. This surplus water will perch on the bedrock interface and flow down-gradient under the force of gravity. The higher recharge to the upper aquifer is illustrated as 0.0005 m/d, with the recharge to the deep fractured aquifer estimated at 0.0001 m/d, This difference must either be removed by evapotranspiration or move downstream as a perched water table.
The impact of a nearby opencast is also illustrated in this figure. Where the flow upstream would normally be directed to the wetland, an opencast can intercept a portion of that flow, leaving the wetland with a decrease in flow and possible degradation. Not all opencasts will be affected, and as a rule of thumb the closest wetlands will be most affected. But then the orientation of the wetland in relation to the opencast is also an important variable that is not always intuitively apparent. In the conceptual model, a lowering of the groundwater table is illustrated that will reverse the flow direction of the interflow. This is illustrative only, and no such prominent effects would be encountered in a real world scenario. Nevertheless, it illustrates what the numerical model aim to achieve.
It is the aim of this model to estimate which wetlands might be impacted and to provide an estimate of the resultant flow decrease. As the model is a simplification of the complexity of nature, the model can only provide approximations. However, these approximations should be adequate to separate those wetlands in potential danger from the apparent unaffected ones, as well as a flow estimate that can be compared in magnitude and importance to surface water in and out flows.
10.3 Numerical Model
A numerical mode was used to estimate the groundwater inputs (GD + GS see below) into the wetland water balance which is deemed10 to consist of the following:
10 Handbook 11: Managing groundwater, RAMSAR Handbooks for the wise use of wetlands 4th edition, 2010
Model Update Report for Welgelegen Colliery- October 2018 51 Geo Pollution Technologies – Gauteng (Pty) Ltd
• P: precipitation (rainfall, snow, dew etc) directly on the wetland +
• R: surface and shallow subsurface inflow to the wetland +
• L: lateral inflow + • OB: over-bank inflow +
• PUi: water pumped into the wetland +
• S: spring flow +
• GD: groundwater discharge into the wetland +
• GS: groundwater seepage into the wetland
GD and GS are the components determined through groundwater modelling. The other components are in the domain of surface water.
10.3.1 Interflow
For the purpose of this study, a 2D model representing the upper regolith layer was constructed. The purpose for this was to create a layer on which infiltrated rainwater can perch. The thickness of the layer was set at 5 meters, the average of the known regolith (soil/softs) thickness.
As stated previously, the 2D numerical model of the regolith is based on the output and calibrated parameters of the 3D model. It is thus not a stand-alone model, but should be considered an indirect coupled model. This renders the model more reliable and the results more trustworthy than a stand-alone model. The thickness of this layer was taken as the average of the available data in the area, while recognising that the conditions in the field will be more complex. However, the exact depth of perching is relatively unimportant considering the size of the horizontal extent within the model. Furthermore, it is impossible to obtain detail information of the regolith layer on such a large scale, and the approximation is considered appropriate for the purpose. The calibrated 3D model hydraulic characteristics were used for permeability.
The designation of the opencasts and wetlands are depicted in Figure 18, while the results are listed in Table 19. It follows from this table that most of the wetlands are not markedly affected. Especially the last column (Loss in mm/a) indicate that all the loss in interflow predicted for the wetlands are noticeably less than the annual rainfall of about 750 mm/a. If the runoff from rainfall is added to this, these numbers become even less important. The following is noteworthy:
• The wetlands surrounding the Wilge River is basically unaffected. The permanent wetlands are not affected at all, while the flow to the seasonal wetlands could be reduced by 10% at most. If this is compared to typical surface water flow volumes of the river, this reduction in flow is insignificant.
• Flow to the permanent wetlands of the tributaries is reduced by typical 10% or less. From a total water flow perspective this is small and unimportant.
• All the seasonal wetlands of the tributaries are predicted to experience a loss on interflow of less than 30%.
• Similarly, the permanent portion of the pans are unaffected by the opencast mining, while the seasonal sections are reduced by 30% at most.
Model Update Report for Welgelegen Colliery- October 2018 52 Geo Pollution Technologies – Gauteng (Pty) Ltd
10.3.2 Deep Groundwater Aquifer
To determine the impact of the deeper permanent groundwater aquifer, an analogous approach has been implemented, but using the full 3D numerical groundwater model. The results are also listed in Table 19.
It also follows from this table that similar trends are obtained than for interflow, but that flow is reduced more, up to 50% in cases. Specifically:
• Base flow to the wetlands surrounding the Wilge River might be reduced by 10%. Compared to typical surface water flow volumes of the river, this reduction in flow is insignificant.
• Flow to the permanent wetlands of the tributaries is reduced by typical 50% or less.
• All the seasonal wetlands of the tributaries are predicted to experience a loss on interflow of up to 70%.
• However, the pans are unaffected by the opencast mining.
In conclusion thus:
• Wetlands along the Wilge River will not be affected at all during mining at Welgelegen.
• However, the wetlands surrounding the tributaries could experience less flow during dry winter months.
• Summer rainfall volumes are at least an order of magnitude more than deep groundwater flow and interflow combined, and should replenish the wetlands seasonally.
Model Update Report for Welgelegen Colliery- October 2018 53 Geo Pollution Technologies – Gauteng (Pty) Ltd
Figure 17: Interflow Conceptual Model
Model Update Report for Welgelegen Colliery- October 2018 54 Geo Pollution Technologies – Gauteng (Pty) Ltd
Figure 18: 2D Designation of Opencasts and Wetlands
Model Update Report for Welgelegen Colliery- October 2018 55 Geo Pollution Technologies – Gauteng (Pty) Ltd
Table 19: Results of Deep Groundwater Flow (GD) and Interflow (GS) on the Wetlands
Flow to Wetland Natural Flow to Wetland During Mining Reduction in Flow (m3/d) Reduction in Flow (%) (m3/d) (m3/d) Wetland Interflo Groundwate Interflo Groundwater Interflow Groundwater Interflow Groundwater w r w Wilge Permanent 688 1449 617 1444 -70 -5 -10% 0%
Wilge Seasonal 442 2047 373 1889 -69 -158 -16% -8%
SW Tributary Permanent 470 768 223 716 -246 -52 -52% -7%
SW Tributary Seasonal 327 801 123 566 -204 -235 -62% -29%
E Tributary Permanent 101 288 64 251 -38 -37 -37% -13%
E Tributary Seasonal 242 853 68 734 -174 -119 -72% -14% NW Tributary 468 687 264 687 -204 0 -44% 0% Permanent NW Tributary Seasonal 381 801 161 696 -220 -104 -58% -13%
W Pan Permanent 0 23 0 31 0 7 0% 32%
W Pan Seasonal 0 85 0 69 0 -15 0% -18%
E Pan Permanent 0 35 0 34 0 -1 0% -2%
E Pan Seasonal 15 139 14 100 -1 -39 -5% -28%
Model Update Report for Welgelegen Colliery- October 2018 56 Geo Pollution Technologies – Gauteng (Pty) Ltd
11 GROUNDWATER MONITORING SYSTEM
11.1 Groundwater Monitoring Network
A groundwater monitoring system has to adhere to the criteria mentioned below. As a result the system should be developed accordingly.
11.1.1 Source, plume, impact and background monitoring
A groundwater monitoring network should contain monitoring positions which can assess the groundwater status at certain areas. The boreholes can be grouped classification according to the following purposes:
• Source monitoring: Monitoring boreholes are placed close to or in the source of contamination to evaluate the impact thereof on the groundwater chemistry.
• Plume monitoring: Monitoring boreholes are placed in the primary groundwater plume’s migration path to evaluate the migration rates and chemical changes along the pathway.
• Impact monitoring: Monitoring of possible impacts of contaminated groundwater on sensitive ecosystems or other receptors. These monitoring points are also installed as early warning systems for contamination break-through at areas of concern.
• Background monitoring: Background groundwater quality is essential to evaluate the impact of a specific action/pollution source on the groundwater chemistry.
11.1.2 System Response Monitoring Network
Groundwater levels: The response of water levels to abstraction is monitored. Static water levels are also used to determine the flow direction and hydraulic gradient within an aquifer. Where possible all of the above mentioned borehole’s water levels need to be recorded during each monitoring event.
11.1.3 Monitoring Frequency
In the operational phase and closure phase, quarterly monitoring of groundwater quality and groundwater levels is recommended. Quality monitoring should take place before after and during the wet season, i.e. during September and March. It is important to note that a groundwater- monitoring network should also be dynamic. This means that the network should be extended over time to accommodate the migration of potential contaminants through the aquifer as well as the expansion of infrastructure and/or addition of possible pollution sources.
11.2 Monitoring Parameters
The identification of the monitoring parameters is crucial and depends on the chemistry of possible pollution sources. They comprise a set of physical and/or chemical parameters (e.g. groundwater levels and predetermined organic and inorganic chemical constituents). Once a pollution indicator has been identified it can be used as a substitute to full analysis and therefore save costs. The use of pollution indicators should be validated on a regular basis in the different sampling positions. The parameters should be revised after each sampling event; some metals may be added to the analyses during the operational phase, especially if the pH drops.
Model Update Report for Welgelegen Colliery- October 2018 57 Geo Pollution Technologies – Gauteng (Pty) Ltd
11.2.1 Abbreviated analysis (pollution indicators)
Physical Parameters:
• Groundwater levels
Chemical Parameters:
• Field measurements: o pH, EC
• Laboratory analyses: o Major anions and cations (Ca, Na, Cl, SO4) o Other parameters (EC)
11.2.2 Full analysis
Physical Parameters:
• Groundwater levels
Chemical Parameters:
• Field measurements: o pH, EC
• Laboratory analyses: o Anions and cations (Ca, Mg, Na, K, NO3, Cl, SO4, F, Fe, Mn, Al, & Alkalinity) o Other parameters (pH, EC, TDS) o Petroleum hydrocarbon contaminants (where applicable, near workshops and petroleum handling facilities) o Sewage related contaminants (E.Coli, faecal coliforms) in borehole in proximity to septic tanks or sewage plants.
11.3 Monitoring Boreholes
DWAF (1998) states that “A monitoring hole must be such that the section of the groundwater most likely to be polluted first, is suitably penetrated to ensure the most realistic monitoring result.”11
The recommended boreholes are listed in Table 20 and the areas to site these monitoring boreholes are shown in Figure 19. These boreholes can be utilised for water level monitoring during operations, as well as groundwater quality monitoring after decommissioning of the site.
However, a monitoring network should be dynamic. This means that the network should be extended over time to accommodate the migration of contaminants through the aquifer as well as the expansion of infrastructure and/or addition of possible pollution sources. An audit on the monitoring network should be conducted annually.
11 Department of Water Affairs and Forestry (DWAF). (1998). Minimum Requirements for the Water Monitoring at Waste Management Facilities. CTP Book Printers. Cape Town.
Model Update Report for Welgelegen Colliery- October 2018 58 Geo Pollution Technologies – Gauteng (Pty) Ltd
Table 20: Proposed Monitoring Positions (New boreholes to be sited by geophysics)
Borehole Depth ID Latitude (South) Longitude (East) Reasoning Frequency Existing/New (mbgl)
Source/Plume MONWEL1 28.86957 -26.1106 30 Quarterly New Monitoring Source/Plume MONWEL2 28.87031 -26.115 30 Quarterly New Monitoring Source/Plume MONWEL3 28.88664 -26.1024 30 Quarterly New Monitoring Source/Plume MONWEL4 28.85619 -26.1337 30 Quarterly New Monitoring Source/Plume MONWEL5 28.83408 -26.1217 30 Quarterly New Monitoring Source/Plume MONWEL6 28.851 -26.1207 30 Quarterly New Monitoring Source/Plume MONWEL7 28.84493 -26.1134 30 Quarterly New Monitoring
Model Update Report for Welgelegen Colliery- October 2018 59 Geo Pollution Technologies – Gauteng (Pty) Ltd
Figure 19: Proposed monitoring positions
Model Update Report for Welgelegen Colliery- October 2018 60 Geo Pollution Technologies – Gauteng (Pty) Ltd
12 GROUNDWATER ENVIRONMENTAL MANAGEMENT PROGRAMME
The groundwater risk assessment methodology is based on defining and understanding the three basic components of the risk, i.e. the source of the risk (source term), the pathway along which the risk propagates, and finally the target that experiences the risk (receptor). The risk assessment approach is therefore aimed at describing and defining the relationship between cause and effect. In the absence of any one of the three components, it is possible to conclude that groundwater risk does not exist.
12.1 Current Groundwater Conditions
The current groundwater conditions at the site are described in sections 5.2, 5.3 and 5.4.
12.2 Predicted Impacts of Mining
The predicted impacts of mining can be summarised as follows:
During Mining
• The Western Opencast is expected to receive 1 000 m3/d. The drawdown from this mine is expected to influence water levels in the North-western Tributary of the Wilge River. Expected water level decline at these receptors is expected to be approximately 35 m.
• The Eastern Opencast is expected to receive inflows of 500 m3/d. The drawdown from this mine is expected to influence water levels in the Eastern Tributary of the Wilge River. Expected water level decline at these receptors is expected to be 30m.
Post-Mining
• Contamination from Western Opencast is expected to affect North-western Tributary of the Wilge River with expected concentration increases of 1000 mg/l with regards to sulphate. The Western Opencast is expected to rebound within 20 years.
• Contamination from the Eastern Opencast is expected to affect Eastern Tributary of the Wilge River with expected concentration increases of 1000 mg/l with regards to sulphate. The Eastern is expected to rebound within 30 years.
12.3 Risk Assessment
A risk assessment was carried out in order to assess the impact of the predicted spread of contamination post mining.
Based on Section 9 it can be seen that none of the privately owned hydrocensus boreholes are predicted to be impacted by the sulphate contamination plumes emanating from the mine. However, the north western and eastern tributaries of the Wilge River are predicted to be impacted on. The predicted SO4 concentrations at these tributaries 100 years post mining 1000 mg/l in both tributaries. According to information gathered during the 2013 study, the water in the area is mostly used for domestic purposes.
If the predicted concentrations are compared with the Department of Water Affairs and Forestry, 1996. South African Water Quality Guidelines (second edition). Volume 1: Domestic Use (Table 21), it can be seen that at a concentration of 1000 mg/l diarrhoea occurs in most individuals and user- adaptation does not occur. The water has a pronounced salty or bitter taste.
Model Update Report for Welgelegen Colliery- October 2018 61 Geo Pollution Technologies – Gauteng (Pty) Ltd
However, as the impacted tributaries are non-perennial the contamination is unlikely to have a lasting effect on the water courses as water will wash down any contaminated seepage and dilute it to unmeasurable concentrations during high rainfall rates.
Therefore, a moderate risk is associated with the cl contamination plume emanating from the mine.
Table 21: Effects of Sulphate on Human Health
Sulphate effects Range Effects (as mg/) 0 - 200 No adverse health effects Tendency to develop diarrhoea in sensitive and some non-adapted 200 - 400 individuals. Slight taste noticeable.
400 - 600 Diarrhoea in most non-adapted individuals. Definite salty or bitter taste.
Diarrhoea in most individuals. User-adaptation does not occur. Pronounced 600 - 1 000 salty or bitter taste. Diarrhoea in all individuals. User-adaptation does not occur. Very strong > 1 000 salty and bitter taste
12.4 Impact Assessment
12.4.1 Assessment Criteria
The criteria for the description and assessment of groundwater impacts were drawn from the EIA Regulations, published by the Department of Environmental Affairs and Tourism (April 1998) in terms of the NEMA12.
In order to determine the significance of an impact, the following criteria would be used: extent, duration, intensity and probability. The extent and probability criteria have five parameters, with a scaling of 1 to 5. Intensity also has five parameters, but with a weighted scaling.
The assessment of the intensity of the impact is a relative evaluation within the context of all the activities and other impacts within the framework of the project. The intensity rating is weighted as 2 since this is the critical issue in terms of the overall risk and impact assessment (thus the scaling of 2 to 10, with intervals of 2). The intensity is thus measured as the degree to which the project affects or changes the environment.
The level of detail as depicted in the EIA regulations was fine-tuned by assigning specific values to each impact. In order to establish a coherent framework within which all impacts could be objectively assessed, it was necessary to establish a rating system, which was applied consistently to all the criteria. For such purposes, each aspect was assigned a value, ranging from one (1) to five
12 Guideline document EIA regulations (April 1998): Implementation of sections 21, 22 and 26 of the environment conservation act.
Model Update Report for Welgelegen Colliery- October 2018 62 Geo Pollution Technologies – Gauteng (Pty) Ltd
(5), depending on its definition. This assessment is a relative evaluation within the context of all the activities and the other impacts within the framework of the project. An explanation of the impact assessment criteria is defined below in Table 22.
Model Update Report for Welgelegen Colliery- October 2018 63 Geo Pollution Technologies – Gauteng (Pty) Ltd
Table 22: Explanation of the EIA criteria
Criteria Description
Nature Includes a description of what causes the effect, what will be affected and how it will be affected.
Extent The physical and spatial scale of the impact.
Duration The lifetime of the impact is measured in relation to the lifetime of the proposed development.
Examining whether the impact is destructive or benign, whether it destroys the impacted Intensity environment, alters its functioning, or slightly alters the environment itself. This describes the likelihood of the impacts actually occurring. The impact may occur for any Probability length of time during the lifecycle of the activity, and not at any given time. Status Description of the impact as positive, negative or neutral.
A synthesis of the characteristics described above and assessed as low, medium or high. A Significance distinction will be made for the significance rating without the implementation of mitigation measures and with the implementation of mitigation measures.
This is the level of knowledge/information that the environmental impact practitioner or a Confidence specialist had in his/her judgement. Examining whether the impacted environment can be returned to its pre-impacted state once the Reversibility cause of the impact has been removed. Replaceability Examining if an irreplaceable resource is impacted upon Cumulative Synthesis of different impacts in concert, considering the knock-on impacts thereof.
Model Update Report for Welgelegen Colliery- October 2018 64 Geo Pollution Technologies – Gauteng (Pty) Ltd
12.4.2 Nature and Status
The nature of the impact is the consideration of what the impact will be and how it will be affected. This description is qualitative and gives an overview of what is specifically being considered. That is, the nature considers ‘what is the cause, what is affected, and how is it affected. The status is thus given as being positive, negative or neutral, and is deemed to be either direct or indirect in impact.
12.4.3 Extent
The physical and spatial scale of the impact is classified in Table 23.
12.4.4 Duration
The lifetime of the impact is measured in relation to the lifetime of the project, as per Table 24.
12.4.5 Intensity
This will be a relative evaluation within the context of all the activities and the other impacts within the framework of the project, as per Table 25.
12.4.6 Probability
This describes the likelihood of the impacts actually occurring. The impact may occur for any length of time during the lifecycle of the activity, and not at any given time. The probability classes are rated in Table 26.
12.4.7 Level of Significance
The level of significance is expressed as the sum of the area exposed to the risk (extent), the length of time that exposure may occur over in total (duration), the severity of the exposure (intensity) and the likelihood of the event occurring (probability). This leads to a range of significance values running from ‘no impact’ to ‘extreme’.
The significance of the impacts has been determined as the consequence of the impact occurring (reflection of chance of occurring, what will be affected (extent), how long will it be affected, and how intense is the impact) as affected by the probability of it occurring, this translates to the following formula:
Significance value = (Extent + Duration + Intensity) x Probability
Each impact is considered in turn and assigned a rating calculated using the results of this formula, and presented as a final rating classification according to Table 16. A distinction will be made for the significance rating of (a) without the implementation of mitigation measures, and, (b) with the implementation of mitigation measures.
12.4.8 Identifying Potential Impacts with Mitigation Measures
In order to gain a comprehensive understanding of the overall significance of the impact, after implementation of the mitigation measures, it will be necessary to re-evaluate the impact. Significance with mitigation is rated on the following scale as contemplated in Table 27 below.
Low (L): The impact is mitigated to the point where it is of limited importance.
Model Update Report for Welgelegen Colliery- October 2018 65 Geo Pollution Technologies – Gauteng (Pty) Ltd
Medium (M): Notwithstanding the successful implementation of the mitigation measures, to reduce the negative impacts to acceptable levels, the negative impact will remain of significance. However, taken within the overall context of the project, the persistent impact does not constitute a fatal flaw.
High (H): The impact is of major importance. Mitigation of the impact is not possible on a cost- effective basis. The impact is regarded as high importance and taken within the overall context of the project, is regarded as a fatal flaw. An impact regarded as high significance, after mitigation could render the entire development option or entire project proposal unacceptable.
12.4.9 Impact Assessment
Based on the impact assessment criteria as detailed in the preceding paragraph an impact rating is given in Table 25. The table also summarises all the groundwater related EMP’s and should be implemented during the operation of the facility.
Model Update Report for Welgelegen Colliery- October 2018 66 Geo Pollution Technologies – Gauteng (Pty) Ltd
Table 23: Impact Extent
Lowering of groundwater Spread of contamination Criteria Description Scoring levels (During mining) (Post mining)
Without Mitigation (WOM)
Footprint The impacted area extends only as far as the activity, such as footprint occurring within the total site area. 1 Site The impact could affect the whole, or a significant portion of the site. 2 Local Impact could affect the adjacent landowners. 3
Regional Impact could affect the wider area around the site, that is, from a few kilometres, up to the wider Council region 4 3 4
Impact could have an effect that expands throughout a significant portion of South Africa – that is, as a minimum National 5 has an impact across provincial borders.
Without Mitigation (WM) Footprint The impacted area extends only as far as the activity, such as footprint occurring within the total site area. 1 Site The impact could affect the whole, or a significant portion of the site. 2 Local Impact could affect the adjacent landowners. 3 3 3 Regional Impact could affect the wider area around the site, that is, from a few kilometres, up to the wider Council region 4
Impact could have an effect that expands throughout a significant portion of South Africa – that is, as a minimum National 5 has an impact across provincial borders.
Model Update Report for Welgelegen Colliery- October 2018 67 Geo Pollution Technologies – Gauteng (Pty) Ltd
Table 24: Impact Duration
Lowering of groundwater Spread of contamination (Post Criteria Description Scoring levels (During mining) mining)
Without Mitigation (WOM)
The impact will either disappear with mitigation or will be mitigated through a natural process in a period shorter Short term 1 than any of the development phases (i.e. less than 2 years). Short to Medium term The impact will be relevant through to the end of the construction phase (i.e. less than 5 years). 2 Impact will last up to the end of the development phases, where after it will be entirely negated (i.e. related to Medium term 3 each phase development thus less than 10 years). The impact will continue or last for the entire operational lifetime of the development, but will be mitigated by 2 4 Long term direct human action or by natural processes thereafter (i.e. during decommissioning) (i.e. more than 10 years, or a 4 maximum of 60 years). This is the only class of impact that will be non-transitory. Mitigation either by man or natural process will not Permanent occur in such a way or in such a time span that the impact can be considered transient (i.e. will remain once the 5 site is closed). With Mitigation (WM) The impact will either disappear with mitigation or will be mitigated through a natural process in a period shorter Short term 1 than any of the development phases (i.e. less than 2 years). Short to Medium term The impact will be relevant through to the end of the construction phase (i.e. less than 5 years). 2 Impact will last up to the end of the development phases, where after it will be entirely negated (i.e. related to Medium term 3 each phase development thus less than 10 years). The impact will continue or last for the entire operational lifetime of the development, but will be mitigated by 2 3 Long term direct human action or by natural processes thereafter (i.e. during decommissioning) (i.e. more than 10 years, or a 4 maximum of 60 years). This is the only class of impact that will be non-transitory. Mitigation either by man or natural process will not Permanent occur in such a way or in such a time span that the impact can be considered transient (i.e. will remain once the 5 site is closed).
Model Update Report for Welgelegen Colliery- October 2018 68 Geo Pollution Technologies – Gauteng (Pty) Ltd
Table 25: Impact Intensity
Lowering of groundwater levels Spread of contamination (Post Criteria Description Scoring (During mining) mining)
Without Mitigation (WOM)
Low The impact alters the affected environment in such a way that the natural processes or functions are not affected. 2
The impact alters the affected environment in such a way that the natural processes or functions are slightly Low-Medium 4 affected. 2 8 Medium The affected environment is altered, but functions and processes continue, albeit in a modified way. 6 Medium-High The affected environment is altered, and the functions and processes are modified immensely. 8 Function or process of the affected environment is disturbed to the extent where the function or process High 10 temporarily or permanently ceases. With Mitigation (WM)
Low The impact alters the affected environment in such a way that the natural processes or functions are not affected. 2
The impact alters the affected environment in such a way that the natural processes or functions are slightly Low-Medium 4 affected. 2 6 Medium The affected environment is altered, but functions and processes continue, albeit in a modified way. 6 Medium-High The affected environment is altered, and the functions and processes are modified immensely. 8 Function or process of the affected environment is disturbed to the extent where the function or process High 10 temporarily or permanently ceases.
Model Update Report for Welgelegen Colliery- October 2018 69 Geo Pollution Technologies – Gauteng (Pty) Ltd
Table 26: Impact Probability
Spread of Lowering of groundwater levels Criteria Description Scoring contamination (Post (During mining) mining)
Without Mitigation (WOM) The possibility of the impact occurring is none, due either to the circumstances, design or experience (less than Improbable 1 24% chance of occurring). The possibility of the impact occurring is very low, either due to the circumstances, design or experience (25 – Possible 2 49%).
Likely There is a possibility that the impact will occur to the extent that provisions must therefore be made (50 – 69%). 3 3 4
It is most likely that the impacts will occur at some stage of the Development. Plans must be drawn up before Highly likely 4 carrying out the activity (70 – 89%). The impact will take place regardless of any prevention plans, and only mitigation actions or contingency plans to Definite 5 contain the effect can be relied upon (90 – 100%). With Mitigation (WM) The possibility of the impact occurring is none, due either to the circumstances, design or experience (less than Improbable 1 24% chance of occurring). The possibility of the impact occurring is very low, either due to the circumstances, design or experience (25 – Possible 2 49%).
Likely There is a possibility that the impact will occur to the extent that provisions must therefore be made (50 – 69%). 3 3 3
It is most likely that the impacts will occur at some stage of the Development. Plans must be drawn up before Highly likely 4 carrying out the activity (70 – 89%). The impact will take place regardless of any prevention plans, and only mitigation actions or contingency plans to Definite 5 contain the effect can be relied upon (90 – 100%).
Model Update Report for Welgelegen Colliery- October 2018 70 Geo Pollution Technologies – Gauteng (Pty) Ltd
Table 27: Impact Significance
Lowering of groundwater levels Spread of contamination (Post Criteria Description Scoring (During mining) mining)
Without Mitigation (WOM)
No Impact There is no impact. 0-9 Low The impacts are less important, but some mitigation is required to reduce the negative impacts. 10 - 24 Medium The impacts are important and require attention; mitigation is required to reduce the negative impacts. 30 - 49
Medium to High The impacts are of medium to high importance; mitigation is necessary to reduce negative impacts. 50 - 74 21 64
High The impacts are of high importance and mitigation is essential to reduce the negative impacts 75 - 89
Extreme The impacts present a fatal flaw, and alternatives must be considered. 90 - 100 With Mitigation (WM) No Impact There is no impact. 0-9
Low The impacts are less important, but some mitigation is required to reduce the negative impacts. 10 - 24
21 36
Medium The impacts are important and require attention; mitigation is required to reduce the negative impacts. 30 -49 Medium to High The impacts are of medium to high importance; mitigation is necessary to reduce negative impacts. 50 - 74 High The impacts are of high importance and mitigation is essential to reduce the negative impacts 75 - 89 Extreme The impacts present a fatal flaw, and alternatives must be considered. 90 - 100
Model Update Report for Welgelegen Colliery- October 2018 71 Geo Pollution Technologies – Gauteng (Pty) Ltd
12.5 Mitigation Measures
The suggested mitigation measures for the operation are summarised in the following paragraphs based on the risk assessment performed.
12.6 Lowering of Groundwater Levels during Operations
The mitigation measures/management measures applicable to the lowering of groundwater levels during operations are listed in Table 28.
Table 28: Mitigation Measures for the Management of Groundwater Level Lowering
Lowering of groundwater levels (During mining) Significance Rating Impact Management Options Significance Rating (WM) (WOM)
Clean and dirty water systems should be separated as planned.
Ensure that the appropriate design facilities (berms, storm water channels etc.) are constructed to ensure clean and dirty water is seperated at the coal handling facilities.
Implement the EMP’s of other environmental related aspects, including pollution prevention and impact minimisation.
Groundwater monitoring boreholes should be sited at designated positions based on infrastructure layout, to comply with the design requirements of a groundwater monitoring system, as recommended. Groundwater monitoring boreholes should be installed to comply with the minimum requirements as set by governmental guidelines.
Monitor static groundwater levels on a quarterly basis in all boreholes within a zone of one kilometre surrounding the mines to ensure that any deviation of the groundwater flow from the idealised predictions is detected in time and can be reacted on appropriately. If it can be proven that the mine is indeed affecting the quantity of groundwater available to certain users, the affected parties should be compensated. This may be done through the installation of additional boreholes for water 21 21 supply purposes, or an alternative water supply. If surface water monitoring shows that the any surface water bodies are affected by mine dewatering, discharge of clean water into theses bodies should be considered. Timing and volumes should be determined by a surface water
Drawdown of water table water of Drawdown specialist. This may be achieved through dewatering boreholes around the mine to extract clean water and ensure dry Groundwater quality must be monitored on a quarterly basis.
The monitoring results must be interpreted annually by a qualified hydrogeologist and the monitoring network should be audited annually to ensure compliance with regulations.
Model Update Report for Welgelegen Colliery- October 2018 72 Geo Pollution Technologies – Gauteng (Pty) Ltd
12.7 Spread of Groundwater Pollution Post-Operations
The mitigation measures/management measures applicable to the spread of groundwater contamination after operations are listed in Table 28.
Table 29: Mitigation Measures for the Management of the Spread of Groundwater Contamination
Spread of contamination (Post mining) Significance Rating Significance Rating Management Options (WOM) (WM) Surface hydrology design should include surface drainage and storm water diversion drains, to meet the requirements of the Water Act. This includes the separation of unpolluted from polluted surface water and the containment of polluted water on site in impoundments. Also, where leachate is generated, it must be contained separately from water which is only slightly polluted through contact with the waste. The DWS requires a Water Quality Monitoring Plan as part of the permitting requirements. This involves background analyses, detection monitoring, investigative monitoring and post-closure monitoring. The Water Quality Monitoring Plan ensures that the water quality in the vicinity of a mine is regularly monitored and reported upon throughout its life,
Surface and groundwater quality and quality monitoring should be continued until a steady state is reached.
64 36 Leaching/Seeping of contaminants into sub-surface into contaminants Leaching/Seeping of
Model Update Report for Welgelegen Colliery- October 2018 73 Geo Pollution Technologies – Gauteng (Pty) Ltd
13 POST-CLOSURE MANAGEMENT PLAN
The groundwater risk assessment methodology is based on defining and understanding the three basic components of the risk, i.e. the source of the risk (source term), the pathway along which the risk propagates, and finally the target that experiences the risk (receptor). The risk assessment approach is therefore aimed at describing and defining the relationship between cause and effect. In the absence of any one of the three components, it is possible to conclude that groundwater risk does not exist.
13.1 Remediation of Physical Activity
The following measures are relevant for remediation of physical activities at the mine:
• Roads that will no longer be used shall be ripped or ploughed and if necessary, appropriately prepared to ensure the re-growth of vegetation. This will include placing back the stored topsoil and planting/seeding.
• Materials, which may hamper re-growth of vegetation, must be removed prior to rehabilitation and disposed of in an approved manner.
• The goal of rehabilitation, with respect to the area from which the product has been extracted, is to leave the area level and even, containing no foreign debris or other materials.
• All scrap, and other foreign materials shall be removed from the bed of neighbouring streams and rivers and disposed of as per other refuse whether these accrue from the mining operation or are washed on to the site from upstream.
• Removal of these materials shall be on a continuous basis while the mine is operating and not only at the start of rehabilitation.
• Tailings in the form of boulders, rocks or oversized gravel screened out during mining will be spread over as wide a portion of the mined river bed as possible or, if buried, shall be covered by a minimum of 500 mm of sand, if at all practically possible.
• Where reeds or other riverine vegetation has been removed from areas for mining, these shall be systematically re-established in the approximate areas they occurred before mining.
• An effective control programme for the eradication of invader species and other alien plants may be required.
• On completion of mining, all buildings, structures or objects on the camp/office sites, shall be completely removed (unless DME requests that the buildings be left) and the site should be fully rehabilitated.
• On completion of mining, the campsite/office site will be rehabilitated through the removal of all facilities, waste and any other feature constructed or established during use of the campsite.
• All areas, devoid of vegetation/grass or where soils have been compacted due to traffic, shall be ploughed or ripped and, if necessary appropriately ensure the re-growth of vegetation (plant or seed).
• French drains shall be compacted and covered with a final layer of topsoil to a height of 10 cm above the surrounding ground surface.
• On completion of mining, the surface of the stockpile and processing areas outside riverbeds shall be ploughed/ripped to a depth of at least 500 mm, graded even and the topsoil previously stored adjacent to the site in a bund wall returned to its original depth over the area.
Model Update Report for Welgelegen Colliery- October 2018 74 Geo Pollution Technologies – Gauteng (Pty) Ltd
• The area shall be appropriately prepared, if necessary, (e.g. fertilized and seeded), to ensure the re-growth of vegetation.
• Settling ponds will be rehabilitated after first spreading tailings from the tailings dump evenly over the floor of the ponds, should this be the method chosen to rehabilitate tailings.
• The tailings will then be covered through spreading the previously excavated material from the pond’s wall evenly over the area.
• The topsoil previously stored adjacent to the site shall then be returned to its original depth over the area.
• The area shall be appropriately prepared, if necessary, to ensure the re-growth of indigenous vegetation.
13.2 Remediation of Storage Facilities
For ROM sites and PCD’s the following measures are applicable:
• AMD can be dealt with as follows; o Completely remove all remaining coal from the site o Use remaining material as backfill in open pits o Recover the RWD and remove polluted soil, if any. o Cover and capping these facilities to reduce water and oxygen reactions o If unsuccessful, consider neutralisation of acidic material o Alternatively, use passive leachate water management and treatment
• Polluted groundwater can be treated as follows: o Reduce hydraulic head by water shedding o Integrate capture-store-release systems o Utilise evapotranspiration o Cap and cover with capillary break o Use drainage diversions o Consider wetland filtration
13.3 Remediation of Environmental Impacts
In the case of permanent cessation of mining, i.e. closure, the mine management team must:
• Ensure that the required rehabilitation of pollution control measures is undertaken in accordance with the closure objectives and the mine closure plan (developed in terms of the Minerals and Petroleum Resources Development Act and the Mining Environmental Series (MEM) and guidelines on closure prepared by the Department of Water Affairs and Forestry. Additional information on closure of pollution control measures is provided in BPG A4: Pollution Control Dams,
• Identify temporary conveyances that will not be required for closure,
o Update the temporary conveyances that are required for closure to permanent structures and,
Model Update Report for Welgelegen Colliery- October 2018 75 Geo Pollution Technologies – Gauteng (Pty) Ltd
o Add any additional conveyances that are required for the closure conditions.
In terms of regulation 9, section 2, the mine management must ensure that:
• All existing impacts from the water management infrastructure are remediated, • Stream diversions systems are managed according to closure plan and closure objectives,
• The potential future impacts, for example, decant from the mine, have been identified and are covered in the closure plan and the closure financial provisions, and
• A procedure is in place in the closure plan for the closure of the final voids, if applicable.
Other practical implications in terms of water management measures for mine closure are as follows:
• All water management infrastructure should be designed and managed to facilitate mine closure. This includes the following considerations:
o The durability and longevity of water management designs, e.g. provision of erosion protection for long-term control of erosion,
o The critical role that water modelling must play in the design process for long-term water quality impact prediction and the design of adequate impact mitigation measures
o The consideration of active versus passive care of the water management infrastructure post-closure,
o And the consideration of the final land use and final land forms should be incorporated into the design of the water management measures for closure
13.4 Remediation of Water Resource Impacts • The post-closure water use should be considered in the design process • The final mine topography should be planned, as far as possible, to be free-draining
• The post-closure water management plan should take cognisance of the likelihood that the water table will rebound in the rehabilitated pits. Modelling of the post-closure groundwater situation will be required to determine:
o The long-term water level in the pit.
o The long-term management of the pit lake.
o The likelihood and position of future decant and/or seepage points, and the impact of these on the receiving water.
o The mine management will need to consider the use of the water post-closure. This water can be used for irrigation purposes if of suitable quality. If the water is not of suitable quality, it will need to be treated prior to re-use or discharge. For further information on treatment of contaminated water the following document can be consulted: Department of Water Affairs and Forestry, 2007. Best Practice Guideline H4: Water Treatment.
Model Update Report for Welgelegen Colliery- October 2018 76 Geo Pollution Technologies – Gauteng (Pty) Ltd
o The institutional arrangement for water re-use in the closure phase will need to be considered and planned.
13.5 Backfill of Pits
The post-closure groundwater management of the opencast should be done in two phases:
• Phase 1: Immediately after closure
• Phase 2: After Rapid Flooding
Please note that the numerical and geochemical model needs to be updated against monitored data during the post-closure phase.
Phase 1: Immediately after closure
During mining the acid generating material and non-acid generating material should have been separated.
• The acid producing material should be placed as low in the pits as possible, followed by the non-acid generating material.
• Rapid flooding should be done by diverting storm water channels and pumping of available groundwater into the pit until the acid producing material is inundated by the water.
Phase 2: After Rapid Flooding
After the acid producing material is inundated by the water:
• The final backfilled opencast topography should be engineered such that runoff is directed away from the opencast areas.
• The final layer (just below the topsoil cover) should be as clayey as possible and compacted if feasible, to reduce recharge to the opencasts.
• Natural berms should then be constructed to allow free drainage of surface water around the rehabilitated pit.
Underground mines
• All openings to the mine need to be sealed or have adequate berms surrounding the openings to prevent surface water entering.
• All boreholes should be sealed from the bottom to the top to prevent groundwater entering the hole and feeding into the mine workings.
• Should depressions created by mining not be able to be filled, then the areas need to be surrounded by berms to prevent surface water ingress to the mine workings.
• Where significant water ingress cannot be prevented, measures should be put in place to intercept ingress water as close as possible to the source in order that it can be pumped out of the mine before its quality can deteriorate through contact with sulphide minerals.
• Properly seal all major water ingress points and ensure that the details of the sealing operation are recorded.
• Institute appropriate water level and water quality monitoring programmes to confirm rate of water rise and water quality as the mine floods. Maintain an ability to access the underground workings until long term discharge and quality predictions have been confirmed.
Model Update Report for Welgelegen Colliery- October 2018 77 Geo Pollution Technologies – Gauteng (Pty) Ltd
• Water quantity and quality data should be collected on a regular, ongoing basis during mine operations. These data will be used to recalibrate and update the mine water management model, to prepare monitoring and audit reports, to report to the regulatory authorities against the requirements of the IWMP and other authorisations and as feedback to stakeholders in the catchment, perhaps via the CMA. See the Monitoring Network section.
• Areas that may have subsided or areas of depressions and/or sinkholes should be filled to create free draining surfaces.
The post-closure groundwater management of underground mines is discussed below:
• Institute water level and water quality monitoring programmes to confirm rate of water rise and water quality as the mine floods.
• Service boreholes need to be plugged from the bottom where they intersect the workings and then grouted through to surface. It would be advantageous if the bord can be backfilled (e.g. with ash) to give further support to the roof to reduce the risk of bord failure which could destroy the plug and grouting thus allowing water to ingress into the workings.
• Shafts should be sealed
14 CONCLUSIONS AND RECOMMENDATIONS
Geo Pollution Technologies (Pty) Ltd (GPT) was appointed by Geovicon Environmental (Pty) Limited (Geovicon) to update the numerical groundwater model and assess the in-pit storage at Welgelen Colliery.
The site is located on the farm Welgelegen 221 IR which is located approximately 20 km east of Delmas in the Mpumalanga Province.
The area is characterised by a gently undulating topography and in the area of the site the slope is more or less in the order of 1:125 (0.008).
Locally drainage is towards the tributary of the Wilge River that flows approximately 2 km west of the proposed mining site in a northerly direction, through the farm Welgelegen. On larger scale, drainage occurs in a northerly direction towards the generalised flow of the Wilge River.
Climatic data was obtained from the DWS weather station Bronkhorstspruit dam (rainfall data and evaporation data) for the Delmas area. The mine is located in the summer rainfall region of Southern Africa with precipitation usually occurring in the form of convectional thunderstorms. The average annual rainfall (measured over a period of 51 years) is approximately 733 mm, with the high rainfall months between October and March.
The area is characterised by consolidated sedimentary layers of the Karoo Supergroup. It consists mainly of sandstone, shale and coal beds of the Vryheid Formation of the Ecca Group and is underlain by the Dwyka Formation of the Karoo Supergroup. Jurassic dolerite intrusions occur throughout the area in the form of sills and outcrops is found throughout the whole area.
According to the 1:500 000 General Hydrogeological Map13 the Karoo Supergroup typically act as secondary aquifers (intergranular and fractured rock aquifers). However, the multi-layered weathering system present on these rocks could prove to have up to two aquifer systems present in the form of a shallow, regolith aquifer with a weathered, intergranular soft rock base associated
13 Haupt, C.J., (1995). An explanation of the 1:500 000 General Hydrogeological Map. Rustenburg 2526. DWAF.
Model Update Report for Welgelegen Colliery- October 2018 78 Geo Pollution Technologies – Gauteng (Pty) Ltd with the contact of fresh bedrock and the weathering zone; and a fractured bedrock aquifer. These aquifer systems are discussed below.
During the hydrocensus, 5 boreholes were available for groundwater level measurement. The groundwater levels varied between a minimum of 4.63 m and a maximum of 10.7 m below ground level.
Water samples were collected from 1 borehole and 5 surface water points. The water results are compared with the maximum recommended concentrations for domestic use as defined by the SANS 241-1: 2015 target water quality limits.
• TDS, Sulphate, Manganese and Aluminium were found to be above the SANS 241 limits in the PCD sample. pH was also found to be outside the SANS limits in the PCD sample.
• Iron and aluminium were found to be above the SANS limits in SWUS.
• Sulphate was found to be above the SANS limits in SWMS.
• Manganese exceeds the SANS limits in the on site in use borehole B1.
• The elevated concentrations of sulphate, manganese and iron on site are likely a result of the coal mining activities in the area.
The GDT calculated a vulnerability value of 55% for the aquifer which is classified as medium. Based on information collected during the hydrocensus it can be concluded that the aquifer system in the study area can be classified as a “Major Aquifer System”, based on the fact that the local population is dependent on groundwater. A Groundwater Quality Management Index of 8 was estimated for the study area from the ratings for the Aquifer System Management Classification. According to this estimate a high level groundwater protection is required for the aquifer.
Geochemical assessment
GPT collected 3 geochemical samples at the Welgelegen Colliery on the 16th of October 2018. Two samples were collected at discard positions and one overburden sample was collected in pit.
The samples were sent to SANAS accredited laboratory (UIS Organic Laboratory (Pty) Ltd) for analysis. All three samples were analysed by quantitative X-ray diffraction, ICP-MS and a leach test.
In summary the report indicates the following regarding the geochemical samples:
The main characteristic of a hypothetical coal mine has been sketched using the chemical analyses of discard material, XRD analyses of those sample, as well as the leachate emanating from these rocks under a controlled leachate test. The result stipulate that rocks stored above the water table (saturated zone) would more prone to the generation of AMD, compared to rocks underneath the water table (saturated zone).
Hydrogeological Impacts
Based on the numerical flow and transport modelling performed, the following hydrogeological impacts were identified:
During Mining
• The Western Opencast is expected to receive 1 000 m3/d. The drawdown from this mine is expected to influence water levels in the North-western Tributary of the Wilge River. Expected water level decline at these receptors is expected to be approximately 10 m.
Model Update Report for Welgelegen Colliery- October 2018 79 Geo Pollution Technologies – Gauteng (Pty) Ltd
• The Eastern Opencast is expected to receive inflows of 500 m3/d. The drawdown from this mine is expected to influence water levels in the Eastern Tributary of the Wilge River. Expected water level decline at these receptors is expected to be 5 m.
Post-Mining
• Contamination from Western Opencast is expected to affect North-western Tributary of the Wilge River with expected concentration increases of 2000 mg/l with regards to sulphate. The Western Opencast is expected to rebound within 20 years.
• Contamination from the Eastern Opencast is expected to affect Eastern Tributary of the Wilge River with expected concentration increases of 1000 mg/l with regards to sulphate. The Eastern is expected to rebound within 30 years.
• However, should the mine discard be placed under water, the contamination to the North- western Tributary reduce to about 100 mg/l, and those at the Eastern Tributary reduce to about 50 mg/l. There is thus a big environmental advantage of placing discard below the groundwater level.
• With regard to the post mining contamination, the following needs to be pointed out: o Although no decant is predicted by the model, the groundwater level is predicted to rise to very close to surface in the north-east of the western opencast and in the south- west of the eastern opencast. Should there be occasional seepage to surface, it will be to these areas. o Plume movement from the opencasts will be mostly towards the streams at a low speed of about 10 m/y maximum, depending mainly on slope of the groundwater table. o The contours of plume movement indicate that contamination might reach the Wilge River and its northwester tributary in about 30 to 50 years in the worst case scenario. However, the contamination is unlikely to have a lasting effect on the water courses as they are normally lined with a natural clay layer and thus poorly connected to the groundwater. o Furthermore, the streams are also normally dry and only carry water after rainfall events. This mass of water will wash down any contaminated seepage and dilute it to unmeasurable concentrations. o However, if the mine discard is placed underneath the groundwater level (as is being done right now), Figure 20 indicates that the sulphate reaching the water courses will be of low concentration. o It is also noticeable that the contamination from the plant area will move eastwards and eventually flow into the defunct western opencast at low concentrations. No impact on any stream is thus anticipated resulting from the plant contamination.
With regards to the wetlands the following can be seen:
• Wetlands along the Wilge River will not be affected at all during mining at Welgelegen. • However, the wetlands surrounding the tributaries could experience less flow during dry winter months.
• Summer rainfall volumes are at least an order of magnitude more than deep groundwater flow and interflow combined, and should replenish the wetlands seasonally.
Model Update Report for Welgelegen Colliery- October 2018 80 Geo Pollution Technologies – Gauteng (Pty) Ltd
14.1 Recommendations
The following actions are recommended:
• The practice of depositing discard below the groundwater level is very promising from a groundwater environmental view, and should be maintained meticulously during future mining.
• The monitoring as recommended in the report should be established as soon as possible. Especially the Eastern Opencast does not have adequate monitoring boreholes at present.
• Regularly update the groundwater impact status report and numerical model against monitored data during operations, at least once more before closure.
• Water quantity and quality data should be collected on a regular, ongoing basis during mine operations. These data will be used to recalibrate and update the mine water management model, to prepare monitoring and audit reports, to report to the regulatory authorities against the requirements of the IWMP and other authorisations and as feedback to stakeholders in the catchment, perhaps via the CMA.
• The hydrocensus and risk assessment should at least be repeated once before closure to evaluate any impacts
Model Update Report for Welgelegen Colliery- October 2018 81 Geo Pollution Technologies – Gauteng (Pty) Ltd
APPENDIX I: HYDROCENSUS INFORMATION
Model Update Report for Welgelegen Colliery- October 2018 82 Geo Pollution Technologies – Gauteng (Pty) Ltd
APPENDIX II: GEOCHEMICAL DATA DESCRIPTION
Model Update Report for Welgelegen Colliery- October 2018 83 Geo Pollution Technologies – Gauteng (Pty) Ltd
APPENDIX III: NUMERICAL MODEL METHODOLOGY AND SETUP
In this paragraph the setup of the flow model will be discussed in terms of the conceptual model as envisaged for the numerical model, elevation data used, boundaries of the numerical model and assumed initial conditions.
ELEVATION DATA
Elevation data is crucial for developing a credible numerical model, as the groundwater table in its natural state tend to follow topography.
The best currently available elevation data is derived from the STRM (Shuttle Radar Tomography Mission) DEM (Digital Elevation Model) data. The SRTM consisted of a specially modified radar system that flew on board the Space Shuttle Endeavour during an 11-day mission in February of 2000, during which elevation data was obtained on a near-global scale to generate the most complete high-resolution digital topographic database of Earth14. Data is available on a grid of 30 metres in the USA and 90 metres in all other areas.
Several studies have been conducted to establish the accuracy of the data, and found that the data is accurate within an absolute error of less than five metres and the random error between 2 and 4 metres for Southern Africa15. Over a small area as in this study, the relative error compared to neighbouring point is expected to be less than one metre. This is very good for the purpose of a numerical groundwater model, especially if compared to other uncertainties; and with the wealth of data this results in a much improved model.
14 http://www2.jpl.nasa.gov/srtm/ 15 Rodriguez, E., et al, 2005. An assessment of the SRTM topographic products. Technical Report JPL D-31639, Jet Propulsion Laboratory, Pasadena, California.
Model Update Report for Welgelegen Colliery- October 2018 84 Geo Pollution Technologies – Gauteng (Pty) Ltd
Figure 20: Elevation Data
Model Update Report for Welgelegen Colliery- October 2018 85 Geo Pollution Technologies – Gauteng (Pty) Ltd
Figure 21: Model Boundaries
Model Update Report for Welgelegen Colliery- October 2018 86 Geo Pollution Technologies – Gauteng (Pty) Ltd
Figure 22: Lateral Delineation of The Regional Model
Model Update Report for Welgelegen Colliery- October 2018 87 Geo Pollution Technologies – Gauteng (Pty) Ltd
Figure 23: Lateral Delineation In The Mining Area
Model Update Report for Welgelegen Colliery- October 2018 88 Geo Pollution Technologies – Gauteng (Pty) Ltd
Figure 24: Vertical Delineation Of The Modelled Area
Model Update Report for Welgelegen Colliery- October 2018 89