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_______________________________________________________________________________________ Digby Wells and Associates (South Africa) (Pty) Ltd Co. Reg. No. 2010/008577/07. Turnberry Office Park, 48 Grosvenor Road, Bryanston, 2191. Private Bag X10046, Randburg, 2125, South Africa Tel: +27 11 789 9495, Fax: +27 11 069 6801, [email protected], www.digbywells.com _______________________________________________________________________________________ Directors: AJ Reynolds (Chairman) (British)*, GE Trusler (C.E.O), GB Beringer, LF Koeslag, J Leaver*, NA Mehlomakulu*, MJ Morifi*, DJ Otto *Non-Executive _______________________________________________________________________________________
Environmental Impact Assessment
for the Blyvoor Gold Mining
Project, West Rand, Gauteng
Groundwater Report
Project Number:
BVG4880
Prepared for:
Blyvoor Gold Capital (Pty) Ltd
October 2018
http://www.digbywells.com/
Digby Wells Environmental i
This document has been prepared by Digby Wells Environmental.
Report Type: Groundwater Report
Project Name: Environmental Impact Assessment for the Blyvoor Gold
Mining Project, West Rand, Gauteng
Project Code: BVG4880
Name Responsibility Signature Date
Ayabonga
Mpelwane Report writer
October 2018
André van Coller Review
October 2018
This report is provided solely for the purposes set out in it and may not, in whole or in part, be used for any other purpose
without Digby Wells Environmental prior written consent.
Groundwater Report
Environmental Impact Assessment for the Blyvoor Gold Mining Project, West Rand, Gauteng
BVG4880
Digby Wells Environmental ii
DECLARATION OF INDEPENDENCE
Digby Wells and Associates (South Africa) (Pty) Ltd
Contact person: Ayabonga Mpelwane
Digby Wells House
Turnberry Office Park
48 Grosvenor Road
Bryanston
2191
Tel: 011 789 9495
Fax: 011 789 9498
E-mail:
I, Ayabonga Mpelwane as duly authorised representative of Digby Wells and Associates
(South Africa) (Pty) Ltd., hereby confirm my independence (as well as that of Digby Wells and
Associates (South Africa) (Pty) Ltd.) and declare that neither I nor Digby Wells and Associates
(South Africa) (Pty) Ltd. have any interest, be it business, financial, personal or other, in any
proposed activity, application or appeal in respect of Blyvoor Gold Capital (Pty) Ltd, other than
fair remuneration for work performed, specifically in connection with the Environmental
Licensing Process at the Blyvoor Gold Mine, West Rand.
Full name: Ayabonga Mpelwane
Title/ Position: Hydrogeologist
Qualification(s): MSc Geohydrology
Experience (years): 4 years
Groundwater Report
Environmental Impact Assessment for the Blyvoor Gold Mining Project, West Rand, Gauteng
BVG4880
Digby Wells Environmental iii
EXECUTIVE SUMMARY
Digby Wells Environmental (hereinafter Digby Wells) was appointed in 2017 by Blyvoor Gold
Capital (Pty) Ltd (hereinafter Blyvoor Gold) to manage the Environmental Legal application
processes pertaining to the Blyvoor Gold Mining Project and the Section 93 Directive handed
down from the Department of Mineral Resources (DMR) regarding the review of the
Environmental Management Plan (EMP) and other documents submitted with the Section 11
Mining Right transfer application in terms of the Mineral Resources and Petroleum
Development Act, 2002 (Act No. 28 of 2002).
The scope includes the Environmental Authorisation process, a Water Use Licence
Application in terms of the National Water Act, 1998 (Act No. 36 of 1998) (NWA) as well as
address and incorporate comments raised by Interested and Affected Parties during the
2017 EMP process which were not previously included. An updated impact assessment for
the specialist’s studies is required to complete this task. The report within addresses
potential impacts to the groundwater environment by the Tailings Storage Facilities (TSFs).
There are limitations to the groundwater studies; neither groundwater samples nor water
levels were acquired from the project area as identified boreholes were either found to be
dry or destroyed. The groundwater impact assessment report should be updated within the
first year of project initiation in terms of; groundwater levels and groundwater quality. This
data will be obtained from the proposed monitoring boreholes within this report.
Water levels measured from three boreholes in 2003; ranged from 9.95 to 30.59 metres
below ground level (mbgl) and four boreholes were found to be dry. Due to limited
groundwater occurrence, impacts to the groundwater by the Tailings Storage Facilities
(TSFs) may be less.
The following outcomes were observed from the geochemical assessments:
■ All the tailings material mineralogy lack carbonates therefore showing a lack of
neutralizing potential. However, no sulphide bearing minerals (such as pyrite or
arsenopyrite) have been detected, therefore reducing the risk of acid generation;
■ Consistent with the absence of sulphide bearing minerals; sulphide content of the
samples shows that none of them exceed 0.3% S and therefore are unlikely to
generate acid due to the limited sulphide content. However, the acid generation can
be controlled by various factors and all results need to be taken into account;
■ The Net Acid Generating (NAG) and Paste pH of all the samples (with the exception
of TSF6) are acidic therefore the samples are potentially acid generating according to
their pH. TSF6 has a high pH; due to the extraction of the sulphides during the
retreatment process of the tailings contained at the TSF, additionally the higher pH is
attributed to the dolomite content (carbonate) countering any acid production;
■ According to the Net Neutralisation Potential (NNP) samples were observed to have
acid generating potential with the exception of TSF6;
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BVG4880
Digby Wells Environmental iv
■ According to the Neutralisation Potential Ratio (NPR) all samples are regarded as
potentially acid generating; with the exception of TSF6. Although the NPR shows an
acid generating potential these reactions will most likely be of short duration due to
the low sulphide content;
■ All samples fell within the Type 3 waste, requiring a Class C liner. However, it is
observed that the material at Blyvoor TSF No. 6 does not pose an environmental risk
based on the laboratory results yielding the following outcomes:
Acid-base-accounting results consistently show that the material at Blyvoor TSF
No. 6 does not show evidence of acid generation; and
The leachate quality is found to be inert.
All TSFs within the project area were constructed prior to the National Environmental
Management: Waste Act, 2008 (Act 59 of 2008). Therefore the type of material on each
cannot be deposited on the required liner due to the pre-existence of the facilities and
volumes of material already deposited at various TSFs.
Blyvoor TSFs No. 4 and 5 were not sampled and are assumed to be represented by the
majority of the tailings material sampled. Therefore, they are assumed to be potentially acid
generating and classified as Type 3 Waste requiring a Class C liner.
Blyvoor TSFs No. 6 and No. 7 will be re-mined during operation, risk to the groundwater
environment will reduce as a potential contamination source will be undergoing depletion
throughout this process, therefore this is a positive action with regards to impact to the
groundwater environment.
The following are management objectives defined for the operation phase:
■ Maintenance of the inactive TSFs is proposed to be conducted by developing an
effective return water system, where this does not exist, to manage excess water that
may accumulate at the tailings facilities;
■ Installation of a Class C liner on TSF4 when reclaimed and planned to operate post
reclamation;
■ Groundwater monitoring should be conducted to assess the time series water level
and water quality trends; and
■ Affected receptors (if proven through monitoring) should be compensated.
The following are management objectives defined for the decommissioning and post-closure
phase:
■ The TSFs should be rehabilitated;
■ Shaped to allow for free draining in order to reduce infiltration of rain water;
■ Groundwater monitoring should be conducted to assess the time series water level
and water quality trends; and
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Digby Wells Environmental v
■ Affected receptors (if proven through monitoring) should be compensated.
All samples fell within the Type 3 waste, requiring a Class C liner. TSF6 material is
recommended to be placed within a Class D liner facility as laboratory results show that it is
not expected to pose an environmental risk
All TSFs are pre-existing and are not lined, therefore operations at Blyvoor TSF No. 6 will
continue without a liner in place.
The area is known to have a limited shallow aquifer and the groundwater encountered by
Golder (2003) may potentially be drainage from the existing TSFs. This drainage is likely to
be contaminating leachate and it recommended that boreholes are drilled at the existing
TSFs for the acquisition of water samples from which the chemistry of the potential
contamination emanating from the facilities may be known.
It is proposed that a numerical groundwater flow and contaminant transport model be done
once updated data is available. This will serve as a predictive tool, identifying the future
impacts of the potential contamination plume associated with the TSFs, i.e. flow direction,
extent and to identify receptors that are at the highest risk as a result of the existence of the
TSFs (if any).
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TABLE OF CONTENTS
1 Introduction ....................................................................................................................... 1
1.1 Project Background ................................................................................................. 3
1.2 Terms of Reference ................................................................................................. 3
1.3 Description of the Activities to be Undertaken ......................................................... 3
1.3.1 Site Layout ....................................................................................................... 4
1.3.2 Tailings Retreatment Plant ............................................................................... 4
1.3.3 No. 5 Shaft Metallurgical Treatment Plant ........................................................ 4
1.3.4 Tailings Storage Facilities ................................................................................. 4
1.3.5 Support Infrastructure ....................................................................................... 9
2 Details of Specialist ......................................................................................................... 10
3 Aims and Objectives ....................................................................................................... 10
4 Methodology.................................................................................................................... 11
4.1 Desktop study ....................................................................................................... 11
4.2 Fieldwork ............................................................................................................... 11
4.3 Geochemical and Waste Assessment ................................................................... 13
4.3.1 Sample Collection ........................................................................................... 13
4.3.2 Laboratory Analysis ........................................................................................ 13
4.3.3 Waste Classification ....................................................................................... 17
4.4 Hydrogeological Conceptual Modelling .................................................................. 19
4.5 Impact Assessment ............................................................................................... 19
5 Assumptions and Limitations .......................................................................................... 19
6 Geochemical and Waste Assessment ............................................................................ 20
6.1 Rock Mineralogy.................................................................................................... 20
6.2 Acid-Base Accounting ........................................................................................... 21
6.2.1 Paste pH ........................................................................................................ 21
6.2.2 Net Acid Generating (NAG) pH ....................................................................... 21
6.2.3 Sulphur Speciation ......................................................................................... 21
6.2.4 Net Neutralisation Potential (NNP) ................................................................. 21
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6.2.5 Neutralisation Potential Ratio (NPR) ............................................................... 22
6.3 Waste Classification .............................................................................................. 22
6.3.1 Total Concentration Results ........................................................................... 22
6.3.2 Leachable Concentration Results ................................................................... 22
6.3.3 Classification .................................................................................................. 26
7 Baseline Environment ..................................................................................................... 27
7.1 Climate .................................................................................................................. 27
7.2 Topography and Drainage ..................................................................................... 27
7.3 Geology ................................................................................................................. 27
7.3.1 Quaternary ..................................................................................................... 27
7.3.2 Transvaal Sequence ....................................................................................... 27
7.3.3 Witwatersrand Supergroup ............................................................................. 28
7.3.4 Structural Geology .......................................................................................... 28
7.4 Local aquifers ........................................................................................................ 30
7.5 Groundwater Levels and Flow Direction ................................................................ 30
7.6 Potential Contaminant sources .............................................................................. 31
7.7 Potential Receptors ............................................................................................... 31
8 Screening Assessment ................................................................................................... 32
9 Sensitivity Analysis and No-Go Areas ............................................................................. 33
10 Impact Assessment ......................................................................................................... 33
10.1.1 Operational Phase .......................................................................................... 33
10.1.2 Management/ Mitigation Measures ................................................................. 34
10.2 Decommissioning and Post-Closure Phase ........................................................... 34
10.2.1 Project Activity Assessed ................................................................................ 34
10.2.2 Management/ Mitigation Measures ................................................................. 34
11 Cumulative Impacts ......................................................................................................... 35
12 Unplanned Events and Low Risks .................................................................................. 37
13 Environmental Management Plan ................................................................................... 37
13.1 Project Activities with Potentially Significant Impacts ............................................. 37
13.2 Summary of Mitigation and Management .............................................................. 38
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13.3 Monitoring Plan ..................................................................................................... 41
13.3.1 Water Sampling and Preservation .................................................................. 43
13.3.2 Sampling Frequency ....................................................................................... 43
13.3.3 Parameters to be Monitored ........................................................................... 43
13.3.4 Data Storage .................................................................................................. 43
14 Comments and Responses ............................................................................................. 43
15 Conclusion and Recommendation .................................................................................. 44
15.1 Conclusions ........................................................................................................... 44
15.2 Recommendations ................................................................................................ 45
16 Reference ........................................................................................................................ 46
LIST OF FIGURES
Figure 1-1: Local setting ........................................................................................................ 2
Figure 1-2: Site Layout .......................................................................................................... 8
Figure 4-1: Hydrocensus boreholes .................................................................................... 12
Figure 4-2: Tailings sample locations .................................................................................. 16
Figure 6-1: Class C Containment Barrier Requirements ...................................................... 26
Figure 7-1: Geology ............................................................................................................ 29
Figure 11-1: Mining activity with 10 km radius of project area ............................................. 36
Figure 13-1: Proposed monitoring network .......................................................................... 42
LIST OF TABLES
Table 1-1: Blyvoor TSFs ....................................................................................................... 5
Table 1-2: Doornfontein TSFs ............................................................................................... 6
Table 4-1: Hydrocensus boreholes...................................................................................... 11
Table 4-2: Rock samples collected for geochemical analysis .............................................. 13
Table 4-3: Criteria for interpreting ABA results (Price, 1997) ............................................... 15
Table 4-4: Waste Classification Criteria .............................................................................. 18
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Digby Wells Environmental ix
Table 4-5: Total and leachable concentration threshold limits ............................................. 18
Table 6-1: Mineralogical composition in weight percentage ................................................ 20
Table 6-2: ABA result summary .......................................................................................... 21
Table 6-3: TCT classification ............................................................................................... 24
Table 6-4: LCT classification ............................................................................................... 25
Table 7-1: Local .................................................................................................................. 30
Table 10-1: Description of Activities to be assessed ........................................................... 33
Table 12-1: Unplanned events, low risks and their management measures ........................ 37
Table 13-1: Potentially Significant Impacts of the New Stockpile ......................................... 38
Table 13-2: Identified Impacts ............................................................................................. 39
Table 13-3: Objectives and Outcomes of the EMP .............................................................. 39
Table 13-4: Mitigation.......................................................................................................... 40
Table 13-5: Prescribed Environmental Management Standards, Practice, Guideline, Policy
or Law ................................................................................................................................. 40
Table 13-6: Proposed monitoring boreholes ........................................................................ 41
LIST OF APPENDICES
Appendix A: Laboratory Certificates
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Environmental Impact Assessment for the Blyvoor Gold Mining Project, West Rand, Gauteng
BVG4880
Digby Wells Environmental 1
1 Introduction
Digby Wells Environmental (hereinafter Digby Wells) was appointed in 2017 by Blyvoor Gold
Capital (Pty) Ltd (hereinafter Blyvoor Gold) to manage the Environmental Legal application
processes pertaining to the Blyvoor Gold Mining Project and the Section 93 Directive handed
down from the Department of Mineral Resources (DMR) regarding the review of the
Environmental Management Plan (EMP) and other documents submitted with the Section 11
Mining Right transfer application in terms of the Mineral Resources and Petroleum
Development Act, 2002 (Act No. 28 of 2002).
Digby Wells initially proposed to undertake an amendment process to update the 2017 EMP
submitted with the Section 11 transfer, as well as address comments made by Interested
and Affected Parties (I&APs) during that process. To initiate the Project, Blyvoor Gold
provided the historical EMPs related to the mining operations which are dated 2000, 2002,
2007, 2012, and 2017. A review of information provided by Blyvoor Gold determined that,
inter alia, the application needed to follow a Scoping and Environmental Impact Assessment
(EIA) process in terms of the National Environmental Management Act, 1998 (Act No. 107 of
1998) and the EIA Regulations, dated 2014 (as amended in 2017) thereunder, and not the
initially proposed amendment process as the metallurgical plants require an Air Emissions
Licence. Also noted was the fact that very few Specialist investigations have ever been
undertaken for the former Blyvooruitzicht operation.
The Scoping Report was approved by the DMR in a letter dated 27 March 2018, which
disclosed/requested the following:
■ The 2017 EMP was not approved as part of the Section 11 transfer, and
■ All listed activities not previously authorised must be included in this application
process.
Digby Wells met with the DMR on 23 May 2018 to discuss the implications of the dated EMP
on the current application process, where it was confirmed that the current process can
continue without having to redo the Scoping Phase. The validity of the baseline and impact
assessment information contained in the 2000 EMP was also discussed and it was
determined that Specialist studies will be required to compensate for the lack of Specialist
investigations, to meet the legal requirements to complete the EIA Process, and facilitate a
thorough responses to the I&AP comments.
The Blyvoor Gold Mining Project is located directly south of Carletonville and Welverdiend in
the Gauteng Province, shown Figure 1-1.
Groundwater Report
Environmental Impact Assessment for the Blyvoor Gold Mining Project, West Rand, Gauteng
BVG4880
Digby Wells Environmental 2
Figure 1-1: Local setting
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Environmental Impact Assessment for the Blyvoor Gold Mining Project, West Rand, Gauteng
BVG4880
Digby Wells Environmental 3
1.1 Project Background
The scope of work includes the Environmental Authorisation (EA) process, a Water Use
Licence Application in terms of the National Water Act, 1998 (Act No. 36 of 1998) (NWA) as
well as address and incorporate comments raised by Interested and Affected Parties during
the 2017 EMP process which were not previously addressed. An updated impact
assessment for the specialist’s studies is required to complete this task. This report
addresses potential impacts to the groundwater environment by the Tailings Storage
Facilities (TSFs) according to the following plans:
■ Deposition operations on Blyvoor TSFs No. 6 and No. 7 throughout the duration of
the Project (15 years);
■ Re-mining of Blyvoor TSFs No. 6 and No. 7; and
■ Maintenance of the remaining inactive TSFs, namely:
Blyvoor TSF No. 1;
Blyvoor TSF No. 4;
Blyvoor TSF No. 5;
Doornfontein TSF No. 1;
Doornfontein TSF No. 2;
Doornfontein TSF No. 3; and
■ Also taking into consideration the potential for restarting deposition operations on
Blyvoor TSFs No. 4 and 5.
1.2 Terms of Reference
The existing TSFs pose a risk of groundwater quality deterioration. Due to this potential
impact regarding the facilities; hydrogeological assessments form part of the environmental
authorisation processes. The various contamination sources have been assessed for acid
generation potential and classified according to the National Environmental Management:
Waste Act 59 of 2008 (as amended by the National Environmental Management: Waste
Amendment Act 26 of 2014) (NEM: WA)
1.3 Description of the Activities to be Undertaken
The current Life of Mine (LOM) for the Blyvoor Gold operation exceeds 30 years, however
the Project is planned in detail for 15 years. Associated infrastructure and project activities to
be undertaken are described below.
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1.3.1 Site Layout
The mine consists of the infrastructure listed below (displayed in Figure 1-2):
■ TSFs;
■ Return water dams (RWDs);
■ Shaft; and
■ Plant area.
1.3.2 Tailings Retreatment Plant
The Tailings Retreatment Plant is located to the east of the former Blyvooruitzicht Golf Club.
This plant will require reconstruction to be returned to an operational status. The return water
pipelines for tailings monitoring which runs from the plant to both Blyvoor TSFs No. 6 and
No. 7 will need to be reconstructed due to these having been vandalised.
Reconstruction of surface infrastructure associated with the plant is not expected to have
any significant impacts to the groundwater environment and are therefore not assessed in
detail, a potential impact during reconstruction is hydrocarbon spillage which is address in
Unplanned Events and Low Risks, Section 12 of the report.
1.3.3 No. 5 Shaft Metallurgical Treatment Plant
The underground ore will be treated at the metallurgical treatment plant located at No. 5
Shaft (No. 5 Shaft Plant). The tailings from the treatment of underground ore will be
deposited on Blyvoor TSF No. 6. This plant will be constructed on the existing plant footprint
using the existing foundations.
1.3.4 Tailings Storage Facilities
A total of eight TSFs were included in the transfer and cession of the Mining Right to Blyvoor
Gold which comprises of the following TSFs: Blyvoor TSFs No. 1, 4, 5, 6 and 7, and
Doornfontein TSFs No. 1, 2 and 3.
Blyvoor Gold intends to continue deposition of tailings onto Blyvoor TSF No. 6 as this TSF
has sufficient capacity to store an additional 18 million tons of tailings.
Blyvoor TSF No. 7 is intended to be reclaimed first, followed by Blyvoor TSF No. 6 and the
remainder of the TSFs will remain in care and maintenance until reclamation. The method of
reclamation is hydraulic mining and re-processing at the Tailings Retreatment Plant. Once
reclaimed, the tailings will be gravity fed from Blyvoor TSF No. 7 to the plant for processing.
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1.3.4.1 Blyvoor TSFs
The TSFs associated with the Blyvooruitzicht operation namely; No.1, 4, 5, 6 and No.7 are detailed in Table 1-1.
Table 1-1: Blyvoor TSFs
TSF Description Footprint Height Volume Tonnes
Blyvoor TSF No.1
Blyvoor No. 1 was operated as an emergency dam and because of its
relatively small top surface area, deposition could only take place for a few
hours per day. This TSF is a paddock dam and has no under drainage
system.
29 ha 20 m 4,633,829 6,797,827
Blyvoor TSF No.4 and 5 The TSF was reclaimed prior to ownership by Blyvoor Gold, and has since
been inactive. - - - 435, 500
Blyvoor TSF No.6
Blyvoor No. 6 was used for tailings placement during the reclamation of
Blyvoor No.4 and 5 and tailings from the underground operations. This
ended in August 2013. Tailings were placed in a cyclone upstream
deposition method. Prior to the reclaiming of Blyvoor No. 4 and 5. Blyvoor
No. 6 was divided into two daywall operated compartments. Later the
cyclone placed material from Blyvoor No. 4 and 5 covered the total surface
area of Blyvoor No. 6, combining it into a single storage facility. The RWD
associated with the TSF is not lined. The total capacity of the existing RWD
is 71 500 m3, this excludes the volume which has been allowed for the
regulatory freeboard of 800 mm.
132 ha 26 m 2,9019,056 44,399,155
Blyvoor TSF No.7
Blyvoor No. 7 dam is a paddock dam with no under drainage system. The
dam is the highest TSF and, as indicated in the EMP, dated 2012, the TSF
started showing signs of depression on the western flank of the upper
compartment.
75 ha 48 m 26,741,680 40,460,161
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Digby Wells Environmental 6
1.3.4.2 The Doornfontein TSFs
Details of the three Doornfontein TSFs are provided in Table 1-2 below.
Table 1-2: Doornfontein TSFs
TSF Description Footprint Height Volume Tonnes
Doornfontein TSF No. 1
This TSF was mothballed when it attained its
maximum designed height. The dam is
characterised by steep side slopes with no step-
ins. There is no evident underdrainage system.
The dam was rehabilitated by the construction of
cross walls and perimeter walls on the top surface.
Catchment paddocks have been constructed
around the toe of the dam to prevent the migration
of eroded material. The dam is situated on gently
sloping ground and is not near to any
watercourses. The area is fenced. The dam is
situated on dolomite; as indicated in the EMP,
dated 2012, no sign of instability has been noted.
54 ha 36 m 15,546,000 22,479,516
Doornfontein TSF No. 2
This TSF is characterised by fairly steep side
slopes (1:2) with no step-ins. There is no
underdrainage system evident. The dam is
situated on gently sloping ground and is not
located in close proximity to any watercourses.
Catchment paddocks have been constructed
around the toe of the dam to contain eroded
material. Rehabilitation of the dam was
implemented by the construction of cross walls
37 ha 12 m 6,641,000 9,496,630
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TSF Description Footprint Height Volume Tonnes
and perimeter walls on the top surface. The area
is fenced. The dam is situated on dolomite; as
indicated in the EMP, dated 2012, no sign of
instability has been noted.
Doornfontein TSF No. 3
This TSF is situated on gently sloping ground and
consists of a toe paddock construction. There are
no underdrains and also no solution trenches
around the toe of the dam. Tailings were
delivered via an in-wall piping system into a day
wall operation. Surface water was decanted off
the top surfaces of the paddocks via a penstock
decant system. The penstock decant pipes
conveyed the water by gravity to two return water
dams approximately 500 m from TSF. Catchment
paddocks have been constructed around the toe
of the tailings dam to contain eroded material.
The area is fenced and there are no structures or
services nearby.
73 ha 32 m 11,487,000 17,127,117
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Figure 1-2: Site Layout
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1.3.5 Support Infrastructure
All support infrastructure was included in the 2017 application undertaken by Golder. These
included power supply, roads, water resources and management, as well as waste
management on site. This is discussed in more detail below.
1.3.5.1 Power supply
Electricity supply to the surface and underground infrastructure will be a 132 kV Eskom
supply ex the existing Doornfontein main substation, which will be refurbished. Electricity for
the TSF plant will be obtained from an existing 22kV supply.
1.3.5.2 Roads
All road infrastructure required for the operation is in place.
1.3.5.3 Water use and resources
Blyvoor Gold has a Water Use Licence No 08/C23E/AEFGJ/1000 and water for hydraulic
reclamation will be sourced from underground. Potable water will be supplied by the
Merafong City Local Municipality.
1.3.5.4 Stormwater Management
The polluted runoff from the plant area was collected in trenches and directed to a sump and
pumped back into the plant. Perimeter berms preventing clean stormwater runoff from
entering the site were also in place. Optimisation of the clean and dirty water separation
system at the plant area will take place during the refurbishing of the plant.
The stormwater management measures that will be required during the operation of Blyvoor
TSFs No. 6 and Blyvoor No. 7 are a berm and channel system around the perimeter of the
tailings dams to prevent clean water from entering the operational area and polluted runoff
from leaving the area. The stormwater runoff from Blyvoor TSF No 7 will be captured in a
pollution control dam and re-used in the re-mining process or managed in the control dam if
not possible to us in re-mining. The stormwater management system will be sized to comply
with Regulation 704 of the National Water Act, 1998 (Act 36 of 1998) (NWA). The clean
stormwater runoff diversion system constructed around the perimeter of the tailings dams
will be sized to convey the flood peak generated from a 50-year 24-hour storm on the clean
catchments.
The RWD at Blyvoor TSF No. 6 has the capacity to store the runoff from a 50-year 24-hour
storm event. The RWD capacity has been confirmed and the sediment in the RWD has been
removed. Similarly, the perimeter berm will be sized to prevent the flood peak from a 50-year
24-hour storm falling on the operational area from entering the clean water system. The
polluted runoff will be directed to the pollution control dam. The pollution control dam will be
sized so as to spill on average once in 50 years as per Regulation GN R 704 in terms of the
National Water Act, 1998 (Act No. 36 of 1998). Consideration must also be given to
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Digby Wells Environmental 10
integrating the clean water runoff system with the current diversion channel system
preventing runoff from reporting to the Wonderfonteinspruit.
1.3.5.5 Waste Management
General domestic waste (such as paper, plastic, organic matter, building rubble, wood, etc.)
will be collected in bins and skips on site and transported to the Merafong Municipal landfill
site. Hazardous waste, such as used oil and grease, and oil sludges from oil separators,
etc., will be temporarily stored in a central collection point (in a bunded area), such as at the
on-site salvage yard, for removal by a reputable company for recycling (such as Oilkol) or
disposal.
Domestic wastewater (sewage) will be managed using chemical toilets and existing sewage
plants (a plant designed to handle 1/Ml/day and using the activated sludge process is
located at No.5 Shaft – treated effluent is discharged to the Wonderfonteinspruit or used for
irrigation of vegetated areas on TSFs).
2 Details of Specialist
Ayabonga Mpelwane is a Hydrogeologist employed within the Water Geosciences
Department. She holds a BSc degree in Geology, BSc Honours degree in Hydrogeology and
MSc degree in Hydrogeology; all qualifications were attained from the University of the Free
State. She joined Digby Wells Environmental in 2014. She has been producing numerical
and analytical groundwater models which involve groundwater related impact assessments
and groundwater management plans. Project experience includes:
■ Hydrocensus and groundwater monitoring;
■ Geochemical assessment and waste classification;
■ Open pit and underground impact numerical groundwater modelling;
■ Wellfield impact numerical groundwater modelling;
■ Landfill and ash dump impact analytical and numerical groundwater modelling; and
■ Research: Underground coal gasification impacts on the Karoo aquifers, conducted
for the Water Research Commission.
3 Aims and Objectives
The aims and objectives of this study are to provide:
■ A description of the project area baseline hydrogeological conditions;
■ Predict the long-term impact of TSFs on groundwater quality;
■ Identify the impact of the existing mine infrastructure on potential receptors;
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■ Compile an impact assessment; rating the identified potential groundwater impacts
based on significance scoring before and after mitigation methods are implemented;
and
■ Recommend management measures to minimise impacts of the mine on the
groundwater environment.
4 Methodology
4.1 Desktop study
During this task, all available data was collected from the client and reviewed. This includes
geological, hydrogeological, monitoring, airborne survey data, and meteorological data
collected historically. A review was conducted and interpretations performed to establish a
conceptual idea of the hydrogeological nature of the area.
4.2 Fieldwork
A hydrocensus was conducted in and around the project area during July and August 2018.
During the hydrocensus, Digby Wells’ hydrogeologist visited the site over a period of three
days and obtained a conceptual understanding of the hydrogeological conditions and
surrounding environment. No water levels were obtained, as some boreholes were blocked,
dry and located in areas which had been excavated, details shown in Table 4-1.
Table 4-1: Hydrocensus boreholes
BH ID Latitude Longitude Comments
G1 -26.41999 27.3676 Located within Blyvoor TSF No. 6, most likely
destroyed during construction.
G2 -26.41649 27.355 Found to be dry.
G3 -26.42337 27.35257 Found to be dry.
G4 -26.41481 27.36168 Found to be dry.
G5 -26.41507 27.36237 Found to be dry.
G6 -26.42522 27.3583 Not found, land has been excavated at location.
G7 -26.42373 27.36374 Not found, land has been excavated at location.
Unknown BH1 -26.415745 27.375009 Found to be blocked just below the surface.
Unknown BH2 -26.416350 27.374639 Found to be blocked just below the surface.
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Figure 4-1: Hydrocensus boreholes
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4.3 Geochemical and Waste Assessment
4.3.1 Sample Collection
Digby Wells collected a total of six TSF samples at Blyvoor Gold Mine. Fresh samples were
collected from existing TSFs, by digging approximately a metre into the deposited material
and a sample weighing approximately 1 kg was acquired. The description of the samples is
shown in Table 4-2 and their positions illustrated in Figure 4-2.
Table 4-2: Rock samples collected for geochemical analysis
Sample ID Latitude Longitude Representative material
DTSF1 -26.385206° 27.335108° Doornfontein TSF No. 1
DTSF2 -26.385366° 27.333744° Doornfontein TSF No. 2
DTSF3 -26.379461° 27.324363° Doornfontein TSF No. 3
TSF1 -26.378221° 27.392572° Blyvoor TSF No. 1
Not Sampled - - Blyvoor TSF No. 4
Not Sampled - - Blyvoor TSF No. 5
TSF6 -26.417692° 27.370132° Blyvoor TSF No. 6
TSF7 -26.409800° 27.380838° Blyvoor TSF No. 7
4.3.2 Laboratory Analysis
The samples were submitted to M&L Laboratory Services (Pty) Ltd for the following analysis:
4.3.2.1 XRD
XRD (X-Ray Diffraction) allows for the measurement of the crystal structures within a sample
to determine the mineralogical composition of the material and assists in determining
whether any reactive solids will lead to environmental risks through the study of the various
minerals.
4.3.2.2 Acid-base Accounting
4.3.2.2.1 Paste pH
The paste pH is a type of ABA used to provide a preliminary and quick estimation on the
acid generation potential of rock samples. The samples are placed in a beaker and distilled
water is added to make a paste. From this a measure of the relative acid-generating (pH7) potential of the material can be evaluated.
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4.3.2.2.2 Net Acid Generating (NAG) pH
During NAG pH tests, the crashed samples are placed in a beaker and hydrogen peroxide is
added to make a paste for rapid oxidation. This is allowed to react for approximately 12
hours. The sample is boiled and cooled to room temperature.
The NAG pH is obtained from the paste. From that pH, acid-generating potential of the
samples can be deduced according to the following criteria (Institute for Groundwater
Studies, 2003):
■ > 5.5 is non-acid-generating
■ 3.5 to 5.5 has low acid-generation potential; and
■
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Table 4-3: Criteria for interpreting ABA results (Price, 1997)
Potential
for ARD Criterion Comments
Likely NPR
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Figure 4-2: Tailings sample locations
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4.3.3 Waste Classification
The samples were classified in accordance with the NEM: WA Regulations, by comparison
with Total Concentration Threshold (TCT) and Leachable Concentration Thresholds (LCT).
Leachable concentrations were determined using reagent water to simulate the metal and
anion leachate potential of the tailings under neutral conditions, with only neutral water
allowing leaching to occur. Total Concentrations were determined by aqua regia digestion to
provide a measure of the solid-phase levels of various mineral-forming cations that may be
of environmental concern. These levels allow for the calculation of metal depletion and can
be used as a screening tool to detect constituents which occur in anomalously high
concentrations under unfavourable geochemical conditions.
Total Concentration Threshold limits are subdivided into three categories as follows:
■ TCT0 limits based on screening values for the protection of water resources, as
contained in the Framework for the Management of Contaminated Land (DEA, March
2010);
■ TCT1 limits derived from land remediation values for commercial/industrial land
(DEA, March 2010); and
■ TCT2 limits derived by multiplying the TCT1 values by a factor of 4, as used by the
Environmental Protection Agency, Australian State of Victoria.
Leachable Concentration Threshold (LCT) limits are subdivided into four categories as
follows:
■ LCT0 limits derived from human health effect values for drinking water, as published
by the Department of Water and Sanitation (DWS) and South African National
Standards (SANS);
■ LCT1 limits derived by multiplying LCT0 values by a Dilution Attenuation Factor
(DAF) of 50, as proposed by the Australian State of Victoria;
■ LCT2 limits derived by multiplying LCT1 values by a factor of 2; and
■ LCT3 limits derived by multiplying the LCT2 values by a factor of 4.
GN R634 identifies waste classes (Waste Types 0 to 4) ranging from high risk to low risk,
based on comparison of the Total Concentration (TC) and Leachable Concentration (LC) of
individual constituents as shown in Table 4-4. Waste is assessed by comparison of the total
and leachable concentration of elements and chemical substances in the waste material to
TCT and LCT limits as per Table 4-5.
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Table 4-4: Waste Classification Criteria
Waste
Type Element or chemical substance concentration Disposal
0 LC > LCT3 OR TC > TCT2 Not allowed
1 LCT2 < LC ≤ LCT3 OR TCT1 < TC ≤ TCT2 Class A or Hh:HH
landfill
2 LCT1 < LC ≤ LCT2 AND TC ≤ TCT1 Class B or GLB+ landfill
3 LCT0 < LC ≤ LCT1 AND TC ≤ TCT1 Class C or GLB- landfill
4
LC ≤ LCT0 AND TC ≤ TCT0 for metal ions and inorganic
anions
AND all chemical substances are below the total
concentration limits provided for organics and pesticides
listed
Class D or GLB- landfill
Table 4-5: Total and leachable concentration threshold limits
Parameter Unit TCT0 TCT1 TCT2 Unit LCT0 LCT1 LCT2 LCT3
As, Arsenic mg/kg 5.8 500 2000 mg/l 0.01 0.5 1 4
B, Boron mg/kg 150 15000 60000 mg/l 0.5 25 50 200
Ba, Barium mg/kg 62.5 6250 25000 mg/l 0.7 35 70 280
Cd, Cadmium mg/kg 7.5 260 1040 mg/l 0.003 0.15 0.3 1.2
Co, Cobalt mg/kg 50 5000 20000 mg/l 0.5 25 50 200
Cr total mg/kg 46000 800000 N/A mg/l 0.1 5 10 40
Cr (IV), Chromium (IV) mg/kg 6.5 500 2000 mg/l 0.05 2.5 5 20
Cu, Copper mg/kg 16 19500 78000 mg/l 2 100 200 800
Hg, Mercury mg/kg 0.93 160 640 mg/l 0.006 0.3 0.6 2.4
Mn, Manganese mg/kg 1000 25000 100000 mg/l 0.5 25 50 200
Mo, Molybdenum mg/kg 40 1000 4000 mg/l 0.07 3.5 7 28
Ni, Nickel mg/kg 91 10600 42400 mg/l 0.07 3.5 7 28
Pb, Lead mg/kg 20 1900 7600 mg/l 0.01 0.5 1 4
Sb, Antimony mg/kg 10 75 300 mg/l 0.02 1 2 8
Se, Selenium mg/kg 10 50 200 mg/l 0.01 0.5 1 4
V, Vanadium mg/kg 150 2680 10720 mg/l 0.2 10 20 80
Zn, Zinc mg/kg 240 160000 640000 mg/l 5 250 500 2000
Chloride as Cl mg/kg n/a n/a n/a mg/l 300 15000 30000 120000
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Parameter Unit TCT0 TCT1 TCT2 Unit LCT0 LCT1 LCT2 LCT3
Sulfate as SO4 mg/kg n/a n/a n/a mg/l 250 12500 25000 100000
Nitrate as N mg/kg n/a n/a n/a mg/l 11 550 1100 4400
F, Fluoride mg/kg 100 10000 40000 mg/l 1.5 75 150 600
CN total, Cyanide total mg/kg 14 10500 42000 mg/l 0.07 3.5 7 28
Notes: n/a: no threshold values
4.4 Hydrogeological Conceptual Modelling
The hydrogeological conceptual model was defined based on findings obtained from
the desktop study and the site visit. The conceptual model describes the baseline
groundwater environment in terms of the following:
■ Contaminant sources: The TSFs’ potential to act as groundwater contamination
sources is described as part of the geochemical assessments which forms part of the
conceptual model; and
■ The local aquifer system: This is the saturated zone, which can be made up of
multiple aquifers. This is where potential contamination will migrate with groundwater,
the hydraulic properties within this zone govern the rate at which potential
groundwater contaminants from the identified sources will migrate once they reach
the aquifer; and
■ Groundwater receptors (i.e. the local groundwater users, streams and natural
ecosystem that depend on the groundwater) will be defined.
4.5 Impact Assessment
An impact assessment is provided based on the outcome of the conceptual model and
geochemical studies, with recommended mitigation measures that may be necessary to
address impacts associated with the TSFs.
The impact assessment uses a well-developed and tested numerical rating system that
takes into consideration the intensity, duration, spatial scale and probability of the impacts.
The final task of the study will be to recommend a groundwater monitoring network that
would satisfactorily monitor groundwater conditions (levels and quality).
5 Assumptions and Limitations
The limitation of the groundwater studies is that; neither groundwater samples nor water
levels were acquired from the project area as identified boreholes were either found to be
dry or destroyed. Therefore, the groundwater levels are defined according to the outcomes
of a drilling programme conducted in 2003; however, no groundwater quality data is
available to define the groundwater status from that study. Groundwater levels will be
updated, and the groundwater quality will be obtained from the monitoring boreholes
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recommended in Section 13.3 this report. The current groundwater quality conditions will
serve to define the presence or absence of contamination and provide a basis on which to
define future impacts.
A basic impact assessment is undertaken in this section considering the construction,
operational and closure phases. Not enough information is available to undertake a detailed
impact assessment that includes ratings i.e. water levels, water quality, groundwater flow
direction and predictive modelling to indicate the extent and intensity of the potential
contamination. The impact assessment however takes into consideration all the significant
potential impacts and provides mitigation measures to reduce all expected impacts.
Furthermore, no geochemical sampling was done on Blyvoor TSF No. 4 and 5. Material on
this TSF is assumed to be represented by the majority of the tailings material sampled and
analysed.
6 Geochemical and Waste Assessment
Geochemical samples were submitted to M&L Laboratory Services (Pty) Ltd for analysis.
This section provides an overview of the geochemical results and interpretation. The
laboratory certificates of the geochemical tests are available in Appendix A.
6.1 Rock Mineralogy
The mineralogy of the samples is shown in Table 6-1. Quartz is the primary mineral
composed within the samples; while muscovite, pyrophyllite and clinochlore are secondary.
Dolomite, calcite, bassanite and actinolite are trace minerals.
The mineralogy results show no or very low carbonate mineral content (only found in trace
minerals). Carbonates are beneficial as they have the potential to buffer acid. However no
sulphide bearing minerals (such as pyrite or arsenopyrite) have been detected, therefore
reducing the risk of acid generation.
Table 6-1: Mineralogical composition in weight percentage
Minerals Ideal Composition DTSF1 DTSF2 DTSF3 TSF1 TSF6 TSF7
Actinolite Ca2(Mg,Fe)5Si8O22(OH) - - - - 0.88 -
Bassanite CaSO40.67H20 - - - - 2.08 -
Calcite CaCO3 2.55 - - - - -
Clinochlore (Mg,Fe)5Al(AISi3O10)(OH)8 3.35 1.36 5.49 7.69 13.7 3.46
Dolomite CaMg(CO3)2 - - - - 7.52 -
Muscovite KAl2((OH)2A1Si3O10) 13.32 2.13 9.9 9.39 9.63 4.13
Pyrophyllite Al2Si4O10(OH)2 3.79 7.74 10.44 7.43 5.72 5.24
Quartz SiO2 76.99 88.77 74.17 75.49 60.47 87.17
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6.2 Acid-Base Accounting
The acid-base-accounting results are presented in the Table 6-2 and discussed below.
Table 6-2: ABA result summary
Sample
ID
Total
Sulph
ur S%
Sulphi
de S%
Past
e pH
NA
G
pH
AP (CaCO3
kg/t)
NP (CaCO3
kg/t)
NNP (CaCO3
kg/t) NPR
DTSF1 0.1 0.02 3.1 3.2 3.12 0 -3.12 0
DTSF2 0.17
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The remaining samples have a negative NNP and are therefore observed to have acid
generating potential (DTSF3 having the least potential and TSF7 having the most acid
generating potential).
6.2.5 Neutralisation Potential Ratio (NPR)
The NPR is zero for all samples with the exception of TSF6 (NPR=2.76). All samples are
regarded as potentially acid generating; except for TSF6 which has low acid generating
potential with a sulphide content that is below the detection limit. However, the sulphide
content in general is limited which reduces the likelihood of acid generation.
Although the NPR shows an acid generating potential these reactions will most likely be of
short duration due to the low sulphide content.
6.3 Waste Classification
Results of the TC and LC analysis are shown in Table 6-3 and Table 6-4, respectively. The
results are compared to threshold concentrations published in the NEM:WA Waste
Classification and Management Regulations.
6.3.1 Total Concentration Results
The analysis shows that:
■ TCT0 threshold values of As and Pb are exceeded in all samples from the tailings;
■ TCT0 threshold values of Cr are exceeded in all samples with the exception of
DTSF1;
■ TCT0 threshold values of Cu are exceeded in all samples with the exception of
DTSF1 and DTSF3; and
■ Based on the outcome of the TCT assessment; more than one element exceeds the
TCT0 limits for the tailings’ material therefore the material according to the
regulations is classified as Type 3 waste requiring a Class C liner.
6.3.2 Leachable Concentration Results
The analysis shows that:
■ Mn is in excess in samples DTSF2 and TSF1 for LCT0 threshold values;
■ Ni is in excess in all samples for LCT0 threshold values, with the exception of DTSF3
and TSF6;
■ Based on the outcome of the LCT assessment:
DTSF3 and TSF6 are classified as Type 4 waste requiring disposal in a facility
with a Class D liner; and
The remaining samples are classified as Type 3 waste requiring a Class C liner.
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Material from Blyvoor TSF No. 4 and 5 was not sampled and is assumed to be represented
by the majority of the tailings’ material sampled. Therefore, they are expected to be acid
generating and classified as Type 3 Waste requiring a Class C liner.
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Table 6-3: TCT classification
Constituents Total Concentration Thresholds (mg/kg) Total Concentrations (mg/kg)
TCT0 TCT1 TCT2 DTSF1 DTSF2 DTSF3 TSF1 TSF6 TSF7
Arsenic as As (mg/kg) 5.8 500 2000 57 8.77 41 26 9.51 27
Boron as B (mg/kg) 150 15000 60000
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Table 6-4: LCT classification
Constituents Leachable Concentration Thresholds (mg/l) Leachable Concentrations (mg/l)
LCT0 LCT1 LCT2 LCT3 DTSF1 DTSF2 DTSF3 TSF1 TSF6 TSF7
Arsenic as As (mg/L) 0.01 0.5 1 4
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6.3.3 Classification
Based on the classification method mentioned in the NEM: WA, the samples are classified
as Type 3 waste because the total concentration of more than one constituent of samples is
between the TCT0 and TCT1 threshold values. Additionally, the leachable concentration of
all constituents is between the LCT0 and LCT1 threshold values (with the exception of
DTSF3 and TSF6).
All samples fell within the Type 3 waste, requiring a Class C liner (Figure 6-1). However, it is
observed that the material at Blyvoor TSF No. 6 does not pose an environmental risk based
on the laboratory results yielding the following outcomes:
■ Acid-base-accounting results consistently show that the material at Blyvoor TSF No.
6 does not show evidence of acid generation; and
■ The leachate quality is found to be inert.
Figure 6-1: Class C Containment Barrier Requirements
All TSFs within the project area were constructed prior to the National Environmental
Management: Waste Act, 2008 (Act 59 of 2008). Therefore the type of material on each
cannot be deposited on the required liner due to the pre-existence of the facilities and
volumes of material already deposited at various TSFs (Table 1-1 and Table 1-2).
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7 Baseline Environment
7.1 Climate
Blyvoor Gold is situated in the Highveld climatic zone. The mean annual precipitation (MAP)
for this region ranges from 650 to 900 mm. The wet season is mostly in summer (October to
March), with most rainfall occurring in January and the dry season is experienced in winter.
Temperatures during summer range from 17 to 27°C with maximum of 38°C. Temperatures
in winter range from 0 to 13°C, occasionally reaching lows down to -13°C.
7.2 Topography and Drainage
The mine is located in the Vaal Water Management Area (WMA) as revised in 2016
(Republic of South Africa Government Gazette Vol. 615 no. 40279), previously subdivided
into the Lower Vaal, Middle Vaal and Upper Vaal WMA.
The project area is mainly located on a topographic high compared to the immediate
surroundings; it is located within quaternary catchment C23E, close to the boundary of
quaternary catchment C23G and C23J. Elevation at the project area ranges from 1,483 to
1677 metres above mean sea level (mamsl). Non-perennial streams occur within the project
area, draining towards the Mooiriverloop from a south-east to a north-west direction.
7.3 Geology
The regional geology is characteristic of the following stratigraphic succession from top to
bottom (also discussed below):
■ Quaternary;
■ Transvaal Sequence;
■ Witwatersrand Supergroup.
The local geology is found to be a stratigraphic succession of the Transvaal dolomite
overlain by the younger sedimentary rocks of the Pretoria Group of the Transvaal
Supergroup.
Figure 7-1 shows the surface geology expected in and around the project area.
7.3.1 Quaternary
This horizon is characterised by soil deposits from hillwash, alluvial and windblown origin.
7.3.2 Transvaal Sequence
The Transvaal Sequence occurs throughout the project area. These rocks consist of the
dolomite of the Malmani Subgroup which occurs over the north-western portion of the mine
property, overlain by the Pretoria Group which occurs predominantly in the south eastern
area. The Pretoria Group rocks consist mainly of chert breccia overlain by quartzites and
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shales. The chert breccia is extremely broken containing some cavities. The underlying
dolomite of the Malmani Subgroup varies in thickness from 850 m on the northern boundary
to 1,300 m on the southern boundary.
7.3.3 Witwatersrand Supergroup
The Witwatersrand Supergroup rocks occur at considerable depths beneath the mine
varying from 1 000 m on the northern boundary of the mine to 1 500 m on the southern
boundary. Two reef horizons of the Witwatersrand Supergroup are mined on Doornfontein
namely the Carbon Leader and the Middelvlei reefs (Main Reef). Both these reefs occur in
the Main Conglomerate Formation of the Johannesburg Subgroup. The Carbon Leader is
the principal economic horizon while the Middelvlei reef is not as economical to mine due to
the presence structures and as a result is mined in a scattered manner.
7.3.4 Structural Geology
The mine is divided into two main tectonic blocks. The eastern block is relatively undisturbed
and the western tectonic block hosts numerous faults. Numerous dykes are found in the
rocks of the Witwatersrand Supergroup. A number of these extend into the overlying
dolomite. The structural features that extend into the overlying dolomite and act as
preferential groundwater flow paths into the mine workings. The Eastern and Western
Oberholzer dykes are of Pilanesberg age and cut, in a northeast-southwest direction,
through the middle of the mining right area.
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Figure 7-1: Geology
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7.4 Local aquifers
Two main aquifers are identified within the project area; the shallow perched aquifer and the
unconfined/ semi-confined dolomite aquifers. The shallow perched aquifer is located in the
Pretoria Group sediments overlying the dolomite in areas underlain by clay horizons within
the group; unconfined/ semi-confined dolomite aquifers are located within the Transvaal
Sequence as well as some of the weathered zones of the Pretoria Group.
7.5 Groundwater Levels and Flow Direction
Golder (2003) conducted a drilling programme of seven boreholes (G1 – G7) within the
project area. Only three boreholes were found to have water, and these water levels ranged
from 9.95 to 30.59 metres below ground level (mbgl). The remaining four boreholes were dry
as detailed in Table 7-1. Due to limited groundwater occurrence, impacts to the groundwater
by the TSFs may be less. This is however applicable in the absence of preferential
groundwater flow paths (faults and dykes), that connect the potential contamination sources
and the local receptors. Additionally the nature of the local aquifer may either occur solely as
a perched or a shallow aquifer experiencing impacts of dewatering in some areas may be
present (with isolated areas where aquifer is depleted). Drilling by Golder was undertaken
within a limited are, relatively limited depth (ranging from 43 to 63 mbgl) and drilling may
have potentially been targeted in an area located within the radius of influence of a cone of
depression resulting from dewatering. Therefore, no conclusion may be drawn about the
nature of the local shallow aquifer from these investigations and more investigations would
have to be conducted to define its nature.
The baseline groundwater flow direction in the weathered zone is expected to follow the
local topography, therefore migrating in a north-westerly direction towards the Mooiriverloop.
Dewatering activities that have been taking place since the 1930s (Golder, 2017) have been
observed to have affected the shallow aquifer. This is shown by the numerous boreholes
having been found to be dry. There is also a presence of sinkholes on site due to mining
activities. Groundwater flow direction may differ depending on the hydraulic head gradient
present as a result of dewatering and presence of sinkholes.
Table 7-1: Local
BH ID Latitude Longitude Depth (m) Water Level
(mbgl)
G1 -26.41999 27.3676 43 Dry
G2 -26.41649 27.355 46 Dry
G3 -26.42337 27.35257 63 18.32
G4 -26.41481 27.36168 36 Dry
G5 -26.41507 27.36237 57 Dry
G6 -26.42522 27.3583 50 30.59
G7 -26.42373 27.36374 33 9.95
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7.6 Potential Contaminant sources
TSFs are potential contamination sources to the groundwater; namely:
■ Deposition operations on Blyvoor TSF No. 6 and No. 7 throughout the duration of the
Project (15 years);
■ Re-mining of Blyvoor TSF No. 6 and Blyvoor TSF No. 7; and
■ Maintenance of the remaining inactive TSFs, namely:
Blyvoor TSF No. ;
Blyvoor TSF No. 4
Blyvoor TSF No. 5;
Doornfontein TSF No. 1;
Doornfontein TSF No. 2;
Doornfontein TSF No. 3; and
■ Also taking into consideration the potential for restarting deposition operations on
Blyvoor TSF No. 4 and 5.
The material stored within these facilities are relatively fine in grain size, exposed to air and
moisture during deposition or as precipitation infiltrates. These conditions allow for chemical
reactions that potentially produce leachate. The severity of the chemical concentrations of
the leachate will then vary based on the extent of the leachate formation conditions
mentioned above and the constituents of the parent material. More detail regarding the
definition of the potential contamination source is found in Section 6.
As Blyvoor TSFs No. 6 and No. 7 are progressively mined during retreatment operations,
risk to the groundwater environment will reduce as a potential contamination source will be
undergoing depletion throughout this process.
7.7 Potential Receptors
Potential receptors are the parts of the system in and around the project area, which may be
impacted negatively if the groundwater quality deteriorates as a result of the TSFs. The
potential receptors are identified as humans that use groundwater for domestic use and
surface water bodies that receive baseflow.
No private boreholes were identified during the hydrocensus however there are settlements
(Carletonville, Welverdiend, Wedela and Khutsong) surrounding the mine which potentially
could have boreholes currently or in future, making use of the groundwater as source of the
water supply.
Dams and non-perennial streams (draining towards the Mooiriverloop), within the project
area may be affected should the groundwater be contaminated, and they receive baseflow.
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8 Screening Assessment
A total of eight TSFs were considered during this impact assessment. All TSFs are existing
disturbed areas on site and there are no greenfield areas associated with the Blyvoor Gold
operation. The proposed project activities are the following:
■ Deposition operations on Blyvoor TSFs No. 6 and No. 7 throughout the duration of
the Project (15 years);
■ Re-mining of TSFs Blyvoor No. 6 and No. 7; and
■ Maintenance of the remaining inactive TSFs, namely:
Blyvoor TSF No. 1;
Blyvoor TSF No. 4 ;
Blyvoor TSF No. 5 ;
Doornfontein TSF No. 1;
Doornfontein TSF No. 2;
Doornfontein TSF No. 3; and
■ Also taking into consideration the potential for restarting deposition operations on
Blyvoor TSF No. 4 and 5.
8.1 Alternatives for operation, and re-mining of Blyvoor TSFs No. 4
and 5
All TSFs are pre-existing facilities and are not lined. Therefore operations are planned to be
undertaken on Blyvoor TSF No. 6 and will continue without a liner in place. To rectify the
conditions of facilities that aren’t lined for future operations, deposition of tailings material
once the TSFs have been retreated should be onto a suitable liner in accordance with the
NEM: WA; on a Class C liner as recommended in Section 6.3
Alternative operation and reclamation of the Blyvoor TSF No. 4 and 5 is proposed to be
conducted in the following manner:
■ Blyvoor TSF No. 4 is proposed to be deposited on TSF No. 5;
■ Following the depletion of the material within TSF No. 4, a liner is will be placed;
■ Material deposited on TSF No. 4 during operation will then be placed on a Class C
liner; and
■ Material on TSF No. 5 will then be reclaimed.
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9 Sensitivity Analysis and No-Go Areas
No-go areas were not identified for this study as the assessment is based on existing tailings
facilities and currently there are no plans to construct any new facilities, although
consideration is being given to the area of the old golf course for possible use as a TSF.
10 Impact Assessment
A basic impact assessment is undertaken in this section considering the
construction, operation and closure phases. Not enough information is available to
undertake a detailed impact assessment that includes ratings. For example, water
levels, water quality, groundwater flow direction and predictive modelling to indicate the
extent and intensity of the potential contamination. The impact assessment however takes
into consideration all the significant potential impacts and provides mitigation measures to
reduce all expected impacts to the receptors discussed in Section 7.7. It should be taken into
consideration that the project area is expected to have deep water levels; consequently,
impact to the groundwater environment may be reduced as a result. This is however
applicable in the absence of preferential groundwater flow paths (faults and dykes), that may
connect the potential contamination sources and the local aquifers.
The existing TSFs have the potential to impact the groundwater quality environment
negatively due to leaching, resulting in deteriorating groundwater quality. The list of project
activities can be found in Table 10-1. Only project activities that are likely to result in a
groundwater impact are assessed below.
Table 10-1: Description of Activities to be assessed
Project Phase Project Activity Project Structures
Construction
TSFs under assessment are
existing and no new TSFs will
be constructed therefore this
phase is irrelevant
Not applicable
Operations Tailings generation and storage TSFs
Mine Decommissioning and
Closure Tailings storage TSFs
10.1.1 Operational Phase
The TSFs may generate contaminating leachate. As rainwater infiltrates through any of the
facilities, metals could be dissolved, and leachate may formed. The leachate could then
seep into the groundwater and potentially migrate, by advection, through the groundwater
environment. Material to be stored within the TSFs is classified as Type 3 waste.
Management measures need to be in place as to eliminate/ reduce any potential impact to
the groundwater environment.
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The tailings deposition material produced either through underground workings or TSF
reclamation is recommended to be underlain by a Class C liner on any reclaimed TSF that is
re-used for storage of tailings.
Reclamation of Blyvoor TSFs No , No. 6, and No. 4 and 5 and deposition of material on TSF
No. 4 which will be lined will reduce the risk to the groundwater environment as the potential
source of contamination will gradually be depleted throughout the reclamation process and
leachate that may be generated on TSF No. 4 will be prohibited from infiltrating into the
groundwater environment because of the liner in place. This is a positive action with regards
to impact to the groundwater environment.
10.1.2 Management/ Mitigation Measures
The following are management objectives defined for the operation phase:
■ Maintenance of the inactive TSFs is proposed to be conducted by developing an
effective return water system, where this does not exist, to manage excess water that
may accumulate at the tailings facilities;
■ Installation of a Class C liner on TSF4 when reclaimed and planned to operate post
reclamation;
■ Groundwater monitoring (as defined in Section 13.3) must be implemented to assess
the time series water level and water quality trends; and
■ Affected receptors (if proven through monitoring) should be compensated.
10.2 Decommissioning and Post-Closure Phase
10.2.1 Project Activity Assessed
Post closure, as during operation, potential leachate formation could result in groundwater
quality deterioration.
10.2.2 Management/ Mitigation Measures
The following are management objectives defined for the decommissioning and post-closure
phase:
■ The TSFs should be rehabilitated;
■ Shaped to allow for free draining to reduce infiltration of rain water;
■ A numerical groundwater model should be done once updated data is available to
complete a full risk and impact assessment;
■ Groundwater monitoring should be conducted to assess the time series water level
and water quality trends; and
■ Affected receptors (if proven through monitoring) should be compensated.
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11 Cumulative Impacts
The cumulative impacts are assessed considering the project area and its surroundings
(within a 10 km radius, presented in Figure 11-1). The area is in the Vaal WMA, located
within quaternary catchment C23E.
Mining related activities are observed to be prevalent within the immediate surroundings,
mostly saturated in the east and south in relation to the project area, however, mining
activities are observed to be limited north-east of the project area.
The TSFs at the project area are an expected source of contamination. Private borehole
users and surface water bodies (through baseflow) are potential receptors. The intensity of
the potential impact to the groundwater is reduced by an observed limited occurrence of
groundwater at the project area. This is assumed to be an impact of dewatering activities
originating from the project area and surrounding mines.
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Figure 11-1: Mining activity with 10 km radius of project area
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12 Unplanned Events and Low Risks
The unplanned events that may happen at the TSFs and the proposed mitigation plans are
listed in Table 12-1.
Table 12-1: Unplanned events, low risks and their management measures
Unplanned
event Potential impact Mitigation / Management / Monitoring
Hydrocarbon
spills from
vehicles and
heavy
machinery.
Hydrocarbon contamination of
the groundwater
Vehicles and heavy machinery should be
serviced and checked in a demarcated
area on a regular basis to prevent
leakages and spills;
Hydrocarbon spill kits must be available
on site at all locations where hydrocarbon
spills could take place;
Where possible; monitoring boreholes,
particularly those located within the
construction area, have to be monitored
for both water level and quality to detect
any changes; and
If a considerable amount of fuel is
accidentally spilled, the contaminated soil
should be removed and disposed of at an
acceptable dumping facility. The
excavated area should be backfilled with
soil of good quality.
Tailings Dam
Failure
Siltation and contamination
of surface water streams
Extended footprint covered
by tailings;
Possible loss of property
and human lives
Proper water management on top of TSF
to ensure stability of walls and base
layers;
Regular monitoring as well as
maintenance;
Ensure TSF operation and deposition is
in line with design criteria
13 Environmental Management Plan
The objective of an Environmental and Social Management Plan (ESMP) is to present
mitigation to manage undue or reasonably avoidable adverse impacts associated with the
development of a project and to enhance potential positive impacts.
13.1 Project Activities with Potentially Significant Impacts
TSFs are potentially contamination sources to the groundwater. The material stored within
these facilities is subject to chemical reactions that potentially produce leachate. Leachate
may be introduced into the groundwater environment; creating a contamination plume,
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deteriorating the groundwater quality and potentially affecting the potential receptors
discussion in Section 7.7.
Table 13-1: Potentially Significant Impacts of the New Stockpile
Aspects Potential Significant impacts
TSFs Groundwater quality deterioration
13.2 Summary of Mitigation and Management
Table 13-2 provides a description of the mitigation and management options for the
environmental impacts anticipated during the construction, operation and decommissioning
and closure phases. Table 13-2 to Table 13-4 provide a summary of the proposed project
activities, environmental aspects and impacts on the receiving environment. Information on
the frequency of mitigation, relevant legal requirements, recommended management plans,
timing of implementation, and roles / responsibilities of persons implementing the EMP are
also provided.
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Table 13-2: Identified Impacts
Activities Phase Mitigation Measures Compliance with standards Time period for implementation
TSFs Operational
Once Blyvoor TSFs No. 7 and 6 have been re-mined,
they should be fitted with a Class C liner if they are to be
re-used as deposition sites;
Maintenance of the inactive TSFs is proposed to be
conducted by developing an effective return water
system to manage excess water that may accumulate at
the tailings facilities;
Installation of a Class C liner on .Blyvoor TSF No.4 if
reclaimed and planned to operate post reclamation;
Groundwater monitoring should be conducted to assess
the time series water level and water quality trends; and
Affected receptors (if proven through monitoring) should
be addressed appropriately.
National Water Act, 1998 (Act No. 36 of 1998);
National Environmental Management: Waste Act,
2008 (Act 59 of 2008) (NEMWA) (as amended by
the National Environmental Management: Waste
Amendment Act 26 of 2014) and List of Waste
Management Activities requiring a Waste
Management Licence (WML) GN 718 of 2008;
DWS Best Practice Guideline G4: Impact
prediction; and
Department of Water and Sanitation (DWS)
(formerly DWAF). 2006. Best Practice Guideline
G3: Water Monitoring Systems.
Quarterly groundwater monitoring should be conducted during project
initiation, monitoring programme should commence as soon as
boreholes are drilled within the first year of operation; and
Affected receptors should be addressed appropriately as soon as
impact is proven through monitoring data.
TSFs Closure
The TSFs should be rehabilitated;
Shaped to allow for free draining to reduce infiltration of
rain water;
Groundwater monitoring should be conducted to assess
the time series water level and water quality trends; and
Affected receptors (if proven through monitoring) should
be addressed appropriately
National Water Act, 1998 (Act No. 36 of 1998);
Department of Water and Sanitation (DWS)
(formerly DWAF). 2006. Best Practice Guideline
G3: Water Monitoring Systems.
Quarterly monitoring should extend up to two years post closure and
based on the trends it can be