environmental impact assessment for the blyvoor gold ... · digby wells and associates (south...

_______________________________________________________________________________________ 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:

[email protected]

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


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;

Groundwater Report


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 Report


BVG4880

Digby Wells Environmental v


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).

Groundwater Report


BVG4880

Digby Wells Environmental vi

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

Groundwater Report


BVG4880

Digby Wells Environmental vii

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

Groundwater Report


BVG4880

Digby Wells Environmental viii

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

Groundwater Report


BVG4880

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

Groundwater Report


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


BVG4880


Figure 1-1: Local setting

Groundwater Report


BVG4880


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. 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.

Groundwater Report


BVG4880


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.

Groundwater Report


BVG4880


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

Groundwater Report


BVG4880


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


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


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

Groundwater Report


BVG4880



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.


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

Groundwater Report


BVG4880


Figure 1-2: Site Layout

Groundwater Report


BVG4880


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

Groundwater Report


BVG4880


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;

Groundwater Report


BVG4880


■ 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.

Groundwater Report


BVG4880


Figure 4-1: Hydrocensus boreholes

Groundwater Report


BVG4880


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



TSF1 -26.378221° 27.392572° Blyvoor TSF No. 1

Not Sampled - - Blyvoor TSF No. 4

Not Sampled - - Blyvoor TSF No. 5



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.

Groundwater Report


BVG4880


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

■

Groundwater Report


BVG4880


Table 4-3: Criteria for interpreting ABA results (Price, 1997)

Potential

for ARD Criterion Comments

Likely NPR

Groundwater Report


BVG4880


Figure 4-2: Tailings sample locations

Groundwater Report


BVG4880


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.

Groundwater Report


BVG4880


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

Groundwater Report


BVG4880


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

Groundwater Report


BVG4880


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

Groundwater Report


BVG4880


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

Groundwater Report


BVG4880


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.

Groundwater Report


BVG4880


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.

Groundwater Report


BVG4880


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

Groundwater Report


BVG4880


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

Groundwater Report


BVG4880


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).

Groundwater Report


BVG4880


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

Groundwater Report


BVG4880


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.

Groundwater Report


BVG4880


Figure 7-1: Geology

Groundwater Report


BVG4880


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

Groundwater Report


BVG4880


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


Blyvoor TSF No. ;

Blyvoor TSF No. 4

Blyvoor TSF No. 5;





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.

Groundwater Report


BVG4880


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


Blyvoor TSF No. 1;

Blyvoor TSF No. 4 ;

Blyvoor TSF No. 5 ;





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.

Groundwater Report


BVG4880


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.

Groundwater Report


BVG4880


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


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 Report


BVG4880


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.

Groundwater Report


BVG4880


Figure 11-1: Mining activity with 10 km radius of project area

Groundwater Report


BVG4880


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,

Groundwater Report


BVG4880


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.

Groundwater Report


BVG4880


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


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


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

environmental impact assessment for the blyvoor gold ... · digby wells and associates (south...

Documents