hydrogeological assessment for the ......2 709 420 1 129 13.07 3 860 428 1 288 14.91 4 639 1 164 1...

_________________________________________________ Digby Wells & Associates (Pty) Ltd. Co. Reg. No. 1999/05985/07. Fern Isle, Section 10, 359 Pretoria Ave Randburg Private Bag

X10046, Randburg, 2125, South Africa Tel: +27 11 789 9495, Fax: +27 11 789 9498, [email protected], www.digbywells.com

_________________________________________________ Directors: AR Wilke, LF Koeslag, PD Tanner (British)*, AJ Reynolds (Chairman) (Br itish)*, J Leaver*, GE Trusler (C.E.O)

*Non-Executive _________________________________________________

p:\projects l to z\universal coal plc\brakfontein\specialists\eia - specialists\groundwater\6 report\final report\hydrogeological assessment_ver3.docx

HYDROGEOLOGICAL ASSESSMENT

FOR THE BRAKFONTEIN EIA

UNIVERSAL COAL (PTY) LTD

SEPTEMBER 2012

Hydrogeological Assessment for the Brakfontein EIA

UNI 1292

ii

This document has been prepared by Digby Wells Environmental.

Report Title: Hydrogeological Assessment for the Brakfontein EIA

Project Number: UNI 1292

Name Responsibility Signature Date

Megan Edwards Report Writer

August 2012

Hesma Cockrell Numerical Modelling H Cockrell September 2012

Lucas Smith Technical Review

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.


UNI 1292

iii

EXECUTIVE SUMMARY

Introduction

The proposed Brakfontein project will be mined in two phases. Opencast activities will define phase 1 of the project with a potential of four seams available for mining. During this phase continued exploration of the underground resource will take place. Opencast mining will focus on extracting seams No. 1 and 2 at an average stripping ratio of 2.48:1.

The overall objective of the groundwater study was to assess the potential impacts of the proposed Brakfontein Mine on the groundwater regime, specifically with regard to:

Mine inflow (and dewatering) rates;

Local changes in groundwater levels during mining and after mine closure; and

Local changes in groundwater quality during and after mine closure.

Methodology

The project consisted of two phases; a fieldwork and a reporting phase. The fieldwork phases consisted of:

An initial site visit, hydro-census and groundwater sampling;

Ground geophysical survey;

Drilling of groundwater characterisation and monitoring boreholes;

Aquifer testing of drilled boreholes; and

Acid base accounting sampling.

The reporting phase consisted of:

A hydrogeological baseline description (conceptual model);

Description of the potential for acid mine drainage;

Numerical modelling;

Impact identification and risk assessment;

Proposed groundwater management measures; and

Groundwater sampling and monitoring.

Groundwater baseline information

Four aquifers have been identified for the project area, a minor shallow weathered aquifer, a minor fractured Karoo aquifer, a Dwyka non-aquifer and a major pre-Karoo dolomitic aquifer. Aquifer tests confirmed the classification of the aquifers (as minor or major) with boreholes intersecting the Karoo Supergroup lithologies achieving water strikes with weak yields ranging from dry to transmissivity of 1.7m2/d whilst the pre-Karoo dolomitic aquifer borehole achieved a yield of 36 1.7m2/d. The testing of


UNI 1292

iv

the pre-Karoo borehole was limited by the 127mm inner diameter size of the borehole casing which restricted the pump size.

Water levels observed at the Brakfontein site varies between 1535 mamsl (BRABH02) and 1586 mamsl (UNI04).However, localised variations may occur as a result of mining activities and groundwater abstraction for agricultural irrigation purposes in some areas.

The Flow direction of the groundwater in the study area correlates fairly well with the surface topography. The Bayesian correlations for pre mining conditions are shown in Figure 4. The water levels observed at the mining area shows a correlation of 79.13% leading to the conclusion that the groundwater flow direction generally mimics the surface topography.

Based on the underlying hydrogeology of the project area, and the corresponding aquifer test results and analyses, the aquifers have been classified according to

Weathered Aquifer Minor Aquifer

Fractured Karoo Aquifer Minor Aquifer

Dwyka Tillite Aquifer Non Aquifer

Basement Karst Aquifer Major Aquifer

Groundwater quality varies with majority of the samples and sample constituents indicating acceptable concentrations compared against the South African National Standard (SANS) 241: 2005 guidelines for drinking water. Samples not complying to acceptable standards are described as follows:

UNI 04 contains elevated to Class II maximum allowable concentrations of nitrate (17.48 mg/l). Nitrates are common in soils and the aquatic environment due to the breakdown of organic matter and tend to increase in shallow groundwater systems associated with agriculture;

UNI07 contains excessive (above Class II maximum allowable) concentrations of fluoride (1.56 mg/l). Presence of fluoride can be found naturally in groundwater or present from anthropogenic contamination. This is the only borehole located on the left of both the faults, which can suggest that the source of fluoride is localised to this area by the fault. Whether the source of fluoride is natural or anthropogenic is undermined;

BRABH 01 contains elevated to Class II (maximum allowable) concentrations of aluminium (0.48 mg/l). The elevated concentrations of aluminium can be attributed to the slightly acidic pH of this borehole; and

BRABH 05 contains elevated to Class II (maximum allowable) concentrations of manganese (0.21 mg/l). The background manganese concentrations are very low for the area as determined by the other groundwater samples indicating an additional source of manganese is present for this borehole. The source can be


UNI 1292

v

natural (intersections with coal layers) or as contamination from historical mine workings.

In general the groundwater has a slightly acidic to slightly alkaline pH range (5.5 to 8.6), with low salinity concentrations (below 550mg/l). Water type for the project area as defined by the Piper diagram indicates a sodium-potassium bicarbonate to calcium-magnesium bicarbonate with a range in sulphate from 5% to 55%. BRABH 01 and BRABH 03 indicate a calcium-magnesium chloride water type. Variability of sulphate and water type is dependent on individual boreholes and no regional distribution trend could be identified.

The acid-base accounting geochemical results indicates all samples are potentially acid generating with negative net neutralising potentials. The average neutralising potential is 0.67 kg/t (CaCO3) and average acid potential is 23.37 kg/t (CaCO3) resulting in an average net neutralising potential of -22.70 kg/t (CaCO3). In general the upper seams (seam 1 and seam 2) indicate the worst results with the lower seam 4 and interburden samples indicating better net neutralising potential results.

Groundwater Numerical Modelling

The potential impact of the proposed mining activities on the groundwater environment has to be qualified, using the baseline geohydrological information and calibrated numerical flow and transport model. The numerical model has been used to simulate the impacts of the open cast areas, underground mine and groundwater receptors. The scenarios modelled include:

Mine dewatering cone of influence after 10 and 20 years of operation (at end of LOM); and

Groundwater contaminant plumes at end of life of mine (20 years) and 20 years post closure.

The predicted inflow rates for the opencast pits and underground mining over the LoM are shown in the table below. Total predicted inflow rates at the proposed Brakfontein mine will range from a minimum of 6.39 l/s calculated for Year 12 to a maximum of 23.16 l/.s calculated for Year 6.

Year OC1 OC2 OC3 OC4 OC5 Total L/s

1 1 272 1 272 14.72

2 709 420 1 129 13.07

3 860 428 1 288 14.91

4 639 1 164 1 803 20.87

5 663 1 172 1 835 21.23


UNI 1292

vi


6 637 1364 2 001 23.16

7 522 1285 1 807 20.91

8 542 798 1 340 15.51

9 1741.5 1 742 20.16

10 749 749 8.67

11 765.5 766 8.86

12 552 552 6.39

13 556.5 557 6.44

14 589 589 6.82

15 825 825 9.55

16 618 618 7.15

17 854.5 855 9.89

18 921.5 922 10.67

19 938.5 939 10.86

20 1245 1 245 14.41

The model qualified and delineated the groundwater drawdown cone (zone in which the groundwater level is lowered as a result of abstraction) during mine dewatering over time. During the operational phase the cone of depression extends approximately 1100m to the south, 300 m to the west and 500m to the north and east of OC 3, 4 and 5, and approximately 400 500m in all directions from OC 1 and 2 (Figure 20).

Seepage from the discard dumps is likely to have elevated salt load consisting predominantly of high TDS, SO4 and Ca concentrations. The results from the acid base accounting tests suggest that the waste rock material is likely to have a net potential to generate acid mine drainage. Groundwater numerical modelling predict that seepage water quality diluted to 5% of the input concentration of 100% is likely to migrate up to between 150m and 300m


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Impact Assessment

The most significant impacts will occur during the operational and decommissioning phase of mining. These are listed below and the impact ratings are given in section 5.

Removal of overburden and backfilling: Rainwater infiltrating through the overburden stockpiles and/or backfilled material and the underlying soils into the groundwater environment could pollute the aquifers, by means of an increased salt load and metals. Acid base accounting tests completed during this investigation indicate a net acid potential in all samples analysed.

Removal of coal (mining process) and ROM coal Stockpile: The removal of coal will lead to a decrease in water level as water flows into the opencast pit.The impact of the proposed mine on regional groundwater resources and users have been qualified using the numerical groundwater model. The model qualified and delineated the groundwater drawdown cone (zone in which the groundwater level is lowered as a result of abstraction) during mine dewatering over time. During the operational phase the cone of depression extends approximately 1100m to the south, 300 m to the west and 500m to the north and east of OC 3, 4 and 5, and approximately 400 500m in all directions from OC 1 and 2 (Figure 20)

Storage, handling and treatment of hazardous products (fuel, explosives, oil) and waste activities (Mine waste discard, sewage): The storage of hazardous products and mine waste material such as sewage may have a potential negative effect on ground-water quality should there be a spillage/leaks that could infiltrate through the soils to reach the groundwater table. Seepage from the discard dumps is likely to have elevated salt load consisting predominantly of high TDS, SO4 and Ca concentrations. The results from the acid base accounting tests suggest that the waste rock material is likely to have a net potential to generate acid mine drainage. Groundwater numerical modelling predict that seepage water quality diluted to 5% of the input concentration of 100% is likely to migrate up to between 100m and 150m


UNI 1292

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TABLE OF CONTENTS

1 INTRODUCTION ............................................................................................................ 13

1.1 PROJECT DESCRIPTION .......................................................................................... 13

1.2 OBJECTIVES ........................................................................................................... 13

1.3 SCOPE OF WORK .................................................................................................... 16

1.4 REPORT STRUCTURE .............................................................................................. 16

2 METHODOLOGY............................................................................................................ 16

2.1 PREAMBLE ............................................................................................................. 16

2.2 INITIAL FIELD VISIT, HYDRO-CENSUS AND SAMPLING ................................................. 17

2.3 SURFACE GEOPHYSICAL INVESTIGATION .................................................................. 21

2.4 DRILLING OF MONITORING BOREHOLES.................................................................... 22

2.5 ACID BASE ACCOUNTING SAMPLING ........................................................................ 24

2.6 AQUIFER TESTS ...................................................................................................... 26

2.7 GROUNDWATER SAMPLING...................................................................................... 27

2.8 FORMULATION OF CONCEPTUAL MODEL ................................................................... 27

2.9 NUMERICAL MODELLING .......................................................................................... 27

2.9.1 Model Objectives ........................................................................................... 28

2.9.2 Software Selection ......................................................................................... 28

2.9.3 Model Limitations ........................................................................................... 28

2.10 IMPACT ASSESSMENT METHODOLOGY ..................................................................... 29

3 CONCEPTUAL MODEL ................................................................................................. 33

3.1 RAINFALL AND EVAPORATION .................................................................................. 34

3.2 TOPOGRAPHY AND DRAINAGE ................................................................................. 34

3.3 GEOLOGY .............................................................................................................. 35

3.3.1 Coal Seams ................................................................................................... 36

3.4 AQUIFERS .............................................................................................................. 40

3.4.1 Shallow Weathered Aquifer ............................................................................ 40

3.4.2 Fractured Aquifer ........................................................................................... 40

3.4.3 Dwyka Tillite................................................................................................... 40

3.4.4 Malmani Dolomite Aquifer .............................................................................. 40


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3.5 GROUNDWATER LEVELS, GROUNDWATER FLOW AND GRADIENT ............................... 41

3.5.1 Groundwater levels ........................................................................................ 41

3.6 RECHARGE ............................................................................................................. 44

3.7 GROUNDWATER QUALITY ........................................................................................ 44

3.8 ACID BASE ACCOUNTING ........................................................................................ 51

3.9 AQUIFER CLASSIFICATION ....................................................................................... 54

3.10 GROUNDWATER USE .............................................................................................. 55

3.10.1 Baseflow to Streams Ecological Receptors ................................................. 56

3.11 MINE PLAN ............................................................................................................. 56

4 NUMERICAL MODELLING............................................................................................. 57

4.1 STEADY STATE MODEL ............................................................................................ 57

4.1.1 Model setup ................................................................................................... 57

4.1.2 Selecting a Model domain and Defining Model Boundary Conditions ............. 57

4.1.3 Top/bottom of aquifer ..................................................................................... 58

4.1.4 Model Mesh ................................................................................................... 59

4.1.5 Layer type ...................................................................................................... 59

4.1.6 Hydraulic Properties applied for the flow model ............................................. 59

4.1.7 Steady state model calibration ....................................................................... 63

4.1.8 Observation boreholes ................................................................................... 63

4.1.9 Sensitivity analysis ......................................................................................... 65

4.2 TRANSIENT GROUNDWATER FLOW MODEL ................................................................ 65

4.2.1 Mine dewatering ............................................................................................ 65

4.2.2 Stress Periods and Time Steps ...................................................................... 65

4.2.3 Transient model ............................................................................................. 66

4.3 GROUNDWATER MODELLING SCENARIOS .................................................................. 68

4.4 SUMMARY OF MODELLING RESULTS ......................................................................... 69

4.4.1 Groundwater balance ..................................................................................... 69

4.4.2 Dewatering cone of influence ......................................................................... 70

4.4.3 Groundwater quality ....................................................................................... 75

5 IMPACT ASSESSMENT ................................................................................................. 78

5.1 CONSTRUCTION PHASE ........................................................................................... 78

5.2 OPERATIONAL PHASE ............................................................................................. 80


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5.3 DECOMMISSIONING PHASE ...................................................................................... 84

6 CUMULATIVE IMPACTS ................................................................................................ 87

7 MITIGATION MEASURES AND MANAGEMENT OPTIONS ......................................... 87

8 MONITORING PROGRAMME ....................................................................................... 95

8.1 MONITORING BOREHOLES ....................................................................................... 95

8.2 GROUNDWATER LEVELS .......................................................................................... 95

8.3 WATER SAMPLING AND PRESERVATION ................................................................... 95

8.3.1 Sample Frequency ......................................................................................... 95

8.3.2 Sample Analysis ............................................................................................ 96

8.4 REPORTING ............................................................................................................ 96

8.5 RESPONSIBILITIES .................................................................................................. 97

9 CONCLUSION ................................................................................................................ 97

9.1 GROUNDWATER BASELINE INFORMATION ................................................................. 97

9.2 GROUNDWATER NUMERICAL MODELLING ................................................................. 99

9.3 IMPACT ASSESSMENT ........................................................................................... 100

10 REFERENCES ............................................................................................................. 102

LIST OF FIGURES

Figure 1: Mean Monthly Rainfall and Evaporation ................................................................................ 34

Figure 2: Stratigraphic Column for the Vryheid Formation in the Delmas Area .................................... 37

Figure 3: Groundwater level elevation .................................................................................................. 42

Figure 4: Bayesian correlation pre-mining ............................................................................................ 43

Figure 5: Groundwater contours ........................................................................................................... 44

Figure 6: Piper Diagram for Groundwater Results ................................................................................ 47

Figure 7: Schoeller Diagram for Groundwater ...................................................................................... 49

Figure 8: Schoeller Diagram for Surface Water .................................................................................... 50

Figure 9: NPR vs pH ............................................................................................................................. 53

Figure 10: Numerical model domain ..................................................................................................... 58

Figure 11: Recharge zones ................................................................................................................... 60

Figure 12: Transmissivity zones calibrated: Layer 1 ............................................................................. 61

Figure 13: Transmissivity zones calibrated: Layer 2 ............................................................................. 62


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Figure 14: Correlation between the observed and simulated heads .................................................... 64

Figure 15: Line chart of observed and simulated heads ....................................................................... 64

Figure 16: Model sensitivity to recharge and transmissivity ................................................................. 65

Figure 18: Location of Modelled Contaminant Sources ........................................................................ 68

Figure 18: Mine dewatering cone of influence year 5 ........................................................................... 72

Figure 19: Mine dewatering cone of influence year 10 ......................................................................... 73

Figure 20: Mine dewatering cone of influence year 20 ......................................................................... 74

................................... 76

................................ 77

LIST OF TABLES

Table 1: Summary of Hydro-census Results ........................................................................................ 18

Table 2: Target Location Summary ....................................................................................................... 21

Table 3: Summary of Newly Drilled Boreholes ..................................................................................... 24

Table 4: Aquifer Test Summary ............................................................................................................ 26

Table 5: Constituents Analysed ............................................................................................................ 27

Table 6: Impact Rating .......................................................................................................................... 30

Table 7: Significance Threshold Limits ................................................................................................. 32

Table 8: Table of Listed Activities ......................................................................................................... 33

Table 9: Regional Chemical Results (all values in mg/l unless otherwise indicated) ........................... 46

Table 10: Summary of ABA results ....................................................................................................... 51

Table 11: ABA Duplicates ..................................................................................................................... 52

Table 12: Aquifer Classification Scheme .............................................................................................. 54

Table 13: Baseflow to Streams ............................................................................................................. 56

Table 14: Boundary coordinates of the model domain ..................................................................... 57

Table 15: Recharge zones .................................................................................................................... 59

Table 16: Transmissivity values: Layer 1 .............................................................................................. 61

Table 17: Transmissivity values: Layer 2 .............................................................................................. 62

Table 18: Boreholes used for steady state model calibration ............................................................... 63

Table 19: Aquifer storage values .......................................................................................................... 66

Table 20: Contaminant Sources and Begin of Contamination as Implemented in Solute Transport Model ..................................................................................................................................................... 67

Table 21: Groundwater inflow rates to mining areas (m3/d) ................................................................. 69


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Table 22: Privately owned boreholes that could potentially be impacted by dewatering...................... 71

Table 24: Mitigation and management measures ................................................................................. 88

LIST OF PLANS

Plan 1: Regional Setting ........................................................................................................................ 14

Plan 2: Mine Layout .............................................................................................................................. 15

Plan 3: Hydro-census Borehole Locality ............................................................................................... 20

Plan 4: Newly Drilled Borehole Locality ................................................................................................ 23

Plan 5: ABA Borehole Locality .............................................................................................................. 25

Plan 6: Surface Catchments ................................................................................................................. 38

Plan 7: Brakfontein Surface Geology .................................................................................................... 39

LIST OF APPENDICES

Appendix A: Geophysical survey results

Appendix B: Borehole Logs

Appendix C: Laboratory results certificates


UNI 1292

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1 INTRODUCTION

Digby Wells Environmental was appointed to conduct a hydrogeological specialist study as

Brakfontein farm. The proposed Brakfontein mining site is located approximately 90km east of Johannesburg, 16km south-east of Delmas and 17km north-west of Leandra, within the Victor Kanye Local and Nkangala District Municipalities of the Mpumalanga Province of South Africa (Plan 1). The Mining Right Application is proposed for the farm portions 6, 8, 9, 10, 20, 26, 30 and the Remaining Extent of the Brakfontein 264 IR farm, which is positioned on the western extent of the Witbank Coalfields.

A groundwater study, including a groundwater flow and transport model had to be developed. The model addresses issues that are relevant to EIA/EMP, focusing in particular on impacts of different mining methods on mine inflow rates over the life of the mine. This report documents the findings obtained from the study.

1.1 Project Description

The proposed Brakfontein project will be mined in two phases. Opencast activities will define phase 1 of the project with a potential of four seams available for mining. During this phase continued exploration of the underground resource will take place. Opencast mining will focus on extracting seams No. 1 and 2 at an average stripping ratio of 2.48:1.

An opencast mining contractor is the preferred option for the opencast mining operations. An initial boxcut will be established during the construction phase of the project with stockpiling of the topsoil and overburden at positions indicated on the plan. Opencast mining will take place using a conventional truck and shovel operation, assisted by roll-over dozing, to allow for continuous backfilling and rehabilitation. The final void will be back filled with overburden from the initial boxcut. Five opencast sections are planned for Brakfontein with an estimated life-of-mine (LoM) of 22 years.

Phase 2 entails underground mining methods of which two seams have been identified for extraction. One underground section has been identified for mining with an estimated LoM of 8 years for this phase.

1.2 Objectives

The overall objective of the groundwater study was to assess the potential impacts of the proposed Brakfontein Mine on the groundwater regime, specifically with regard to:




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UNI 1292

16

1.3 Scope of Work

The full scope of work included the following:

Phase 1 Fieldwork:

Task 1: An initial site visit, hydro-census and groundwater sampling;

Task 2: Ground geophysical survey;

Task 3: Drilling of groundwater characterisation and monitoring boreholes;

Task 4: Acid base accounting sampling; and

Task 5: Aquifer testing and sampling.

Phase 2 Reporting:

Task 1: Hydrogeological baseline description;

Task 2: Potential for acid mine drainage;

Task 3: Numerical modelling;

Task 4: Impact identification and risk assessment;

Task 5: Proposed groundwater management measures; and

Task 6: Groundwater monitoring program.

1.4 Report Structure

The remainder of this report is structured as follows:

Section 2: Site Description

Section 3: Methodology

Section 4: Conceptual Model

Section 5: Numerical Model

Section 6: Impact Assessment

Section 7: Conclusion and Recommendation

2 METHODOLOGY

2.1 Preamble

The project consisted of two phases; a fieldwork and a reporting phase. The fieldwork phases consisted of:

An initial site visit, hydro-census and groundwater sampling;

Ground geophysical survey;

Drilling of groundwater characterisation and monitoring boreholes;


UNI 1292

17

Aquifer testing of drilled boreholes; and

Acid base accounting sampling.

The reporting phase consisted of:

A hydrogeological baseline description (conceptual model);

Description of the potential for acid mine drainage;

Numerical modelling;

Impact identification and risk assessment;

Proposed groundwater management measures; and

Groundwater monitoring program.

2.2 Initial Field Visit, Hydro-census and Sampling

The hydro-census was conducted on farm portions within a 5km radius of the Brakfontein 264 project farms. Farm portions of the farms, Brakfontein 264 IR, Dieplaagte 262 IR, Straffontein 252 IR, Vanggatfontein 251 IR, Rietkruil 249 IR, Rietkruil 278 IR, Middelburg Alias Matjesgoedkruil 266 IR, Havenglen 269 IR, Haverklip 265 IR and Kromdraai 263 IR were investigated during the hydro-census.

In order to locate and access all known boreholes in the area, Digby Wells contacted and

employees to locate the boreholes and other water resources. The following tasks were completed for each borehole:

The co-ordinates were recorded on a handheld Garmin GPS and their locations plotted on Plan 3;

The status of the borehole and equipment installed were recorded;

Access for the piezometer was determined and the water level was measured if possible;

The borehole water was recorded after interviewing the land owners. Water uses identified were domestic and garden use and livestock watering.

This information will be used to help determine the groundwater baseline and will be compared to monitoring data in future. A summary of gathered information is provided in Table 1.

Nine groundwater and two surface water samples (UNI 02, UNI 04, UNI 07, UNI 09, UNI 011, UNI 012, UNI 014, UNI 015, UNI 016, WILGE 01 and WILGE 02) were obtained for chemical analysis. Samples were taken using a single valve, decontaminated bailers or where boreholes were equipped and in use, from the fitted pumps or taps. Standard 1l sample bottles were used and filled to the top. Samples were delivered to Clean Stream Laboratories in Pretoria on the 22nd May 2012.

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UNI 1292

21

2.3 Surface Geophysical Investigation

A surface resistivity geophysical survey was conducted between the 16th and 19th of May and infilling with magnetic geophysics was conducted on the 11th June. During the geophysical investigation, the following actions were taken:

The interim mine plan was studied to identify areas requiring investigation;

Topographic and local drainage maps were studied to investigate areas downstream and upstream of underground and opencast mining areas;

Ground resistivity method was selected due to the presence of dolomite in the area;

The magnetic method was chosen for an infill survey as the method is cost effective and can be utilised to identify dolerite present in the project area;

Resistivity data were recorded in the areas identified during the desktop study;

Magnetic data were recorded as a result of mine plan changes and took place at the start of the drilling programme;

The geophysical data recorded was interpreted in terms of the local geological and hydrogeological conditions;

Based on the interpretation of the geophysical data, sixteen potential targets for the drilling of characterisation boreholes were identified (six from the magnetic survey and ten from the resistivity survey).

The resistivity report and inverse modelled sections as well as the magnetic line graphs are appended to Appendix A. A summary of the target locations is provided below.

Table 2: Target Location Summary

Target ID Y Coord X Coord Method Comments

Target01 -26.2093 28.8768 Resistivity Not Drilled Target02 -26.2084 28.8758 Resistivity Not Drilled Target03 -26.2074 28.8745 Resistivity Drilled Target04 -26.1954 28.8654 Resistivity Not Drilled Target05 -26.1943 28.8666 Resistivity Drilled Target06 -26.1927 28.8684 Resistivity Not Drilled Target07 -26.1990 28.8627 Resistivity Not Drilled Target08 -26.1987 28.8646 Resistivity Not Drilled Target09 -26.2229 28.8340 Resistivity Not Drilled Target010 -26.2234 28.8299 Resistivity Not Drilled Target011 -26.2048 28.8620 Magnetometer Not Drilled Target012 -26.2049 28.8597 Magnetometer Drilled Target013 -26.2073 28.8478 Magnetometer Not Drilled Target014 -26.2082 28.8462 Magnetometer Drilled Target015 -26.2163 28.8503 Magnetometer Drilled Target016 -26.2163 28.8514 Magnetometer Not Drilled


UNI 1292

22

2.4 Drilling of Monitoring Boreholes

A percussion drilling programme was initiated to provide an indication of the groundwater storage and flow characteristics of the structural zones. The borehole localities were sited based on the interpretation of the geophysical survey data.

The drilling commenced from the 11th to 15th of June 2012. Five of the sixteen targeted borehole sites were selected for drilling (Plan 4). The drilling was undertaken by Geosphere Drilling, with an Air Rotary Percussion drilling machine. Drilling supervision was conducted by a geo-technician employed at Digby Wells.

The five boreholes were drilled to a depth of 60 mbgl and the following information was obtained during drilling:

Site co-ordinates;

Colour, drilling chip size at 1 m intervals;

Vertical geological succession and degree of weathering;

Depth of drilling and borehole construction; and

Depth of water strikes, individual water strike yield, final (accumulative) blow yield and rest water level after completion.

A summary of the borehole localities and decision record details are given in Table 3.

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UNI 1292

24

Table 3: Summary of Newly Drilled Boreholes

Borehole ID BRABH01 BRABH02 BRABH03 BRABH04 BRABH05

Date Completed 11/06/2012 12/06/2012 13/06/2012 13/06/2012 14/06/2012

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X coordinate 28.8745 28.8666 28.85973 28.84621 28.85005 Y coordinate -26.20741 -26.19428 -26.20492 -26.20814 -26.21631

Elevation (mamsl) 1549 1542 1554 1563 1577

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(m) 60 60 60 60 60

Blow Yield (l/s) Dry Weak 6.0 Weak 1.8 Water Strike depth

(m) Dry No Strike 15, 27 No Strike 37

Casing Height (m) Buried 1 mbgl 0.27 0.3 0.24 0.43

Static Water Level

(mbgl) 6.402 5.525 5.61 17.16 23.2

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Solid Casing Steel

(Diameter - ID mm) 165 165 165 165 165

Depth from - to (m)

0-6 0-6 0-6 0-6 0-6

Solid Casing

uPVC (Diameter -

ID mm) 127 127 127 127 127

Depth from - to

(m) 0-4, 43-57

0-7, 9-15, 18-37, 43-48, 54-57

0-6, 9-12, 20-26, 29-37, 40-57

0-12, 15-23, 29-34, 40-54

0-34, 43-48

Perforated Casing

uPVC (Diameter -

ID mm) 127 127 127 127 127

Depth from - (m) 4-43, 57-60

7-9, 15-18, 37-43, 48-54, 57-60

6-9, 12-20, 26-29, 37-40, 57-60

12-15, 23-29, 34-40, 54-60

34-43, 48-60

2.5 Acid Base Accounting Sampling

The geochemical sampling of the core was undertaken on the 12th of June 2012 and involved sampling of available core from the proposed opencast area of the project. A total of 20 samples were collected from the opencast area (Plan 5). Of the 20 samples two were selected for quality control checks. All samples were submitted to Waterlab Laboratory in Pretoria for standard ABA analysis including sulphur speciation. The results of the sampling are discussed in Section 3.8.

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2.6 Aquifer Tests

Aquifer tests were conducted at the newly drilled boreholes. Digby Wells Hydrogeologists and In-Situ Groundwater Services conducted the aquifer tests from 25th June to 1st July 2012.

Prior to all aquifer tests, static groundwater levels were measured in the pumping borehole to enable drawdown calculations;

Initially, a step drawdown test (SDT) was conducted, consisting of four steps (60 minutes each) at progressively higher discharge rates for each step;

Constant discharge tests (CDT) were conducted as follow:

24 hours on the BRABH 03, a high yielding borehole of 6 L/s; and

8 hours on BRABH 05, an intermediate yielding borehole of 1.8 L/s;

During the constant discharge test, discharged water was released via a pipe at least 250 m from the tested borehole in order to avoid artificial recharge;

Recovery tests (RT) followed directly after pump shut down at the end of the SDT and CDT. The water level recovery over time was measured in the pumping borehole until at least 90% recovery was reached;

In addition slug tests were conducted on the low yielding boreholes (BRABH 02 and BRABH 04);

The aquifer test data (pumping and slug tests) were interpreted using a number of analytical methods, i.e. Flow Characteristic; Cooper Jacob and Theis. The aquifer test results are summarised in Table 4.

Table 4: Aquifer Test Summary

Borehole

ID

Blow

Yield Test Duration Yield Drawdown

T Value

(Cooper

Jacob)

K- Value

BRABH 02 Weak Slug Test (Out) 20mins 0.051 m/d

BRABH 03 6.0 L/s

Step Drawdown and Recovery 4hrs

1L/s, 2L/s,

3.2L/s, 5.4L/s

1.25m, 2.10m, 3.86m, 6.89m 36m2/d

Constant Discharge and Recovery

24hrs 5.23L/s 8.64m

BRABH 04 Weak Slug Test (In

and Out) 20mins Inconclusive

BRABH 05 1.8 L/s

Step Drawdown and Recovery 2hrs 0.63L/s,

1L/s 11.56m, 32.50m

1.7m2/d

Constant Discharge and Recovery

8hrs 0.57L/s 16.00m


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The high yielding BRABH 03 borehole aquifer test was limited by the 127mm inner diameter casing size, which restricted the pump size and therefore the pumping rate. Thus, only a low total drawdown was achieved.

2.7 Groundwater Sampling

A total of five groundwater samples were collected from the newly drilled boreholes to assess the baseline water quality. Samples were taken using a single valve decontaminated bailer where slug tests were conducted otherwise samples were collected during the aquifer testing programme whilst boreholes were equipped with testing pumps. Standard 1l sample bottles were used and filled to the top. Samples were cooled and transported in a cooler box to be delivered to Clean Stream Laboratory for analysis. Clean Stream holds ISO 17025 accreditation, granted by the South African National Accreditation System (SANAS). The water quality analyses were compared to the SANS 241:2005 drinking water quality standards as a reference. The chemical constituents analysed are listed in Table 5.

Table 5: Constituents Analysed

Analyses Units Analyses Units pH Electrical Conductivity mS/m Aluminium (Al) mg/l Total Alkalinity mg/l Iron (Fe) mg/l Chloride (Cl) mg/l Manganese (Mn) mg/l Sulphate (SO4) mg/l Total Chromium (Cr) mg/l Nitrate (NO3) as N mg/l Copper (Cu) mg/l Ammonium (NH4) as N mg/l Nickel (Ni) mg/l Orthophosphate (PO4) as P mg/l Zinc (Zn) mg/l Fluoride (F) mg/l Cobalt (Co) mg/l Calcium (Ca) mg/l Cadmium (Cd) mg/l Magnesium (Mg) mg/l Lead (Pb) mg/l Sodium (Na) mg/l Total Hardness mg/l Potassium (K) mg/l - -

2.8 Formulation of Conceptual Model

Following the site investigation and data interpretation, a conceptual hydrogeological model for the project area was developed. The conceptual model describes the dynamics of groundwater flow in the pre-mining environment.

2.9 Numerical Modelling

The conceptual model was translated into a numerical model. The MODFLOW and MT3DMS numerical modelling codes were used for this task. The numerical model was calibrated using the data collected during the field investigation phase of this project. Following model calibration several scenarios were simulated to assess the impacts relevant to the EIA/EMP.


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2.9.1 Model Objectives

The objectives of modelling are to predict:




The modelling approach has been as follows:

A steady state regional groundwater flow model has firstly been calibrated using baseline groundwater monitoring data followed by;

Transient model calibration, using time variant information to simulate mine dewatering and contaminant transport; and

Forward modelling which incorporates the stress exerted by mining activities.

2.9.2 Software Selection

The simulation package Processing Modflow Pro (PMWIN Pro), Version 7.0 (Chiang, 2005) was used to simulate groundwater flow. MODFLOW is a modular three-dimensional finite-difference groundwater model published by the U. S. Geological Survey.

MT3D is a modular three-dimensional transport model for the simulation of advection, dispersion, and chemical reactions of dissolved constituents in groundwater systems.

2.9.3 Model Limitations

All numerical modelling simulations require assumptions to be made during the translation of the numerical code into a site-specific model. These assumptions, which reflect data gaps in the conceptual model regarding the aquifer distribution and the aquifer parameters, can result in areas of uncertainty in the model output and predictions. During the development of the site specific hydrogeological conceptual model for the proposed Brakfontein mine, the following data gaps and/or uncertainties were identified:

It is impossible to include all the local complexity of the secondary aquifers. The model assumes average flow conditions across the site;

The spatial distribution and amount of natural and artificial recharge is uncertain; and

In order to accurately calculate dewatering of aquifer storage, daily to monthly mine pushback plans are required. One year mine plans were available for the project and calculated daily groundwater inflow volumes are averaged over the period. Initial, potentially high influx volumes from aquifer storage are therefore also averaged over a period of 1year.

A model sensitivity analysis was carried out to give an indication of which assumptions in model input parameters are most likely to affect the model output. Scenario modelling will address the possible impacts that changes in input parameters will have on the model output (groundwater quality and levels over temporal and spatial distribution).


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2.10 Impact Assessment Methodology

The impact rating process is designed to provide a numerical rating of the various environmental impacts identified for various project activities. The significance rating process follows the established impact/risk assessment formula:

The weight assigned to the various parameters for positive and negative impacts in the formula is presented in Table 6.

Significance = Consequence x Probability

Consequence = Severity + Spatial Scale + Duration Probability = Likelihood of an impact occurring

Hyd

roge

olog

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Ass

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or th

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rakf

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in E

IA

UN

I 129

2

30

Ta

ble

6:

Imp

act

Ra

tin

g

Rati

ng

Se

ve

rity

Sp

ati

al S

cale

D

ura

tio

n

Pro

bab

ilit

y

En

vir

on

men

tal

So

cia

l, C

ult

ura

l an

d

Heri

tag

e

Leg

al

7

Ver

y si

gnifi

cant

impa

ct

on th

e en

viro

nmen

t. Irr

epar

able

dam

age

to

high

ly v

alue

d sp

ecie

s,

habi

tat o

r eco

syst

em.

Per

sist

ent s

ever

e da

mag

e.

Irrep

arab

le d

amag

e to

hi

ghly

val

ued

item

s of

gr

eat c

ultu

ral s

igni

fican

ce

or c

ompl

ete

brea

kdow

n of

so

cial

ord

er.

Pot

entia

l jai

l ter

ms

for

exec

utiv

es a

nd/o

r ver

y hi

gh fi

nes

for t

he

com

pany

. Pro

long

ed,

mul

tiple

litig

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n.

With

draw

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f per

mit

/ cl

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Inte

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iona

l P

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o M

itiga

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6 S

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t im

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on

high

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amag

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ghly

val

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item

s of

cu

ltura

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nific

ance

or

brea

kdow

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soc

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.

Ver

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cant

fine

s an

d pr

osec

utio

ns. M

ultip

le

litig

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n.

Nat

iona

l P

erm

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t M

itiga

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Alm

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Cer

tain

/ H

igh

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abilit

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5

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rious

, lon

g-te

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envi

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l im

pairm

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f ec

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func

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that

m

ay ta

ke s

ever

al y

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to

reha

bilit

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Ver

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wid

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repa

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mag

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hig

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item

s.

Sig

nific

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rose

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d fin

es. V

ery

serio

us

litig

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clud

ing

clas

s ac

tions

.

Pro

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Reg

ion

Pro

ject

Life

Li

kely

4

Ser

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med

ium

term

en

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ffect

s.

Env

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age

can

be re

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ed in

less

th

an a

yea

r

On-

goin

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rious

soc

ial

issu

es. S

igni

fican

t dam

age

to s

truct

ures

/ ite

ms

of

cultu

ral s

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ce.

Maj

or b

reac

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regu

latio

n.

Maj

or li

tigat

ion.

M

unic

ipal

Are

a Lo

ng T

erm

Pr

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le

Hyd

roge

olog

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Ass

essm

ent f

or th

e B

rakf

onte

in E

IA

UN

I 129

2

31

Rati

ng

Se

ve

rity

Sp

ati

al S

cale

D

ura

tio

n

Pro

bab

ilit

y

En

vir

on

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cia

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3

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hort-

term

ef

fect

s bu

t not

affe

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func

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Reh

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quire

s in

terv

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ext

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l sp

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and

can

be

done

in le

ss th

an a

m

onth

.

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goin

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cial

issu

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age

to it

ems

of

cultu

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bre

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of

regu

latio

n w

ith

inve

stig

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n or

repo

rt to

au

thor

ity w

ith p

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cutio

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d/or

mod

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Unl

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or e

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bi

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or p

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cal

envi

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enta

l dam

age

can

be re

habi

litat

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inte

rnal

ly w

ith /

with

out

help

of e

xter

nal

cons

ulta

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ediu

m-te

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pact

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loca

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tion.

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tly

repa

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e. C

ultu

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func

tions

and

pro

cess

es

not a

ffect

ed.

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or le

gal i

ssue

s, n

on-

com

plia

nces

and

bre

ache

s of

regu

latio

n.

Lim

ited

Shor

t Ter

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Lim

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dam

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to

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imal

are

a of

low

si

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canc

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.g. a

d ho

c sp

ills w

ithin

pla

nt a

rea)

. W

ill ha

ve n

o im

pact

on

the

envi

ronm

ent.

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-leve

l rep

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dam

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to c

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ikel

y /

Non

e


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Impacts are rated prior to mitigation and again after consideration of the mitigation measure proposed in the Environmental Management Programme (EMP). The significance of an impact is then determined and categorised into one of four categories, as indicated in Error!

Not a valid bookmark self-reference..

Table 7: Significance Threshold Limits

Score Description Rating

< 35

An acceptable impact for which mitigation is desirable but not essential. The impact by itself is insufficient even in combination with other low impacts to prevent the development being approved. These impacts will result in either positive or negative short term effects on the social and/or natural environment.

Negligible

36 72

An important impact which requires mitigation. The impact is insufficient by itself to prevent the implementation of the project but which in conjunction with other impacts may prevent its implementation. These impacts will usually result in either a positive or negative medium to long-term effect on the social and/or natural environment.

Minor

73 108

A serious impact, if not mitigated, may prevent the implementation of the project (if it is a negative impact). These impacts would be considered by society as constituting a major and usually long-term change to the (natural and/or social) environment and result in severe effects or beneficial effects.

Moderate

> 108

A serious impact, which if negative, may be sufficient by itself to prevent implementation of the project. The impact may result in permanent change. Very often these impacts are immitigable and usually result in very severe effects or very beneficial effects.

Major


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The impact assessment methodology is applied for the four phases of mining (construction, operation, decommissioning and closure) for the identified mining activities. The listed activities are presented in Table 8.

Table 8: Table of Listed Activities

Phase Activity Number Activity

Construction

1 Site Clearing: Removal of topsoil & vegetation

2 Construction of any surface infrastructure e.g. haul roads, pipes, storm water diversion berms (including transportation of materials & stockpiling)

3 Blasting and development of initial box cut for mining (incl. stockpiling from initial cuts).

4 Temporary storage of hazardous product (fuel, explosives) and waste or sewage.

Operation

5 Removal of overburden and backfilling when possible (including drilling/blasting hard overburden & stockpiling)

6 Use and maintenance of haul roads (incl. transportation of coal to washing plant)

7 Removal of coal ( mining process ) and ROM coal Stockpile

8 Water use & storage on site (incl. screening & washing, PCD)

9 Storage, handling and treatment of hazardous products (fuel, explosives, oil) and waste activities (waste, sewage, discard, PCD)

10 Concurrent replacement of overburden, topsoil and re-vegetation

Decommissioning

11 Demolition & Removal of all infrastructure (incl. transportation off site)

12 Rehabilitation (spreading of soil, re-vegetation & profiling/contouring)

13 Installation of post-closure water management infrastructure 14 Environmental monitoring of decommissioning activities

15 Storage, handling and treatment of hazardous products (fuel, explosives, oil) and waste activities (waste, sewage, discard)

Post-closure 16 Post-closure monitoring and rehabilitation

3 CONCEPTUAL MODEL

In every model, the system under investigation is represented by a conceptual model. A conceptual model includes designing and constructing equivalent but simplified conditions for real world problems that are acceptable in terms of the objectives of the modelling and the associated management problems. The conceptual site model for Brakfontein was characterised by incorporating several environmental components, geological and hydrogeological features and characteristics of the area, the static groundwater levels, groundwater flow directions, groundwater flow boundaries, aquifer definitions and taking into


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account the source-pathway-receptor linkage. The Brakfontein site conceptual model is described in the sections below.

3.1 Rainfall and Evaporation

The area falls under the central Mpumalanga/Highveld climatic zone. Precipitation typically occurs as convectional thunderstorms during the warm summer months (October to March). The winter months are characterised by mild to warm days with cold nights and sharp frosts.

Weather stations are located at Middelburg and Bethal and have been used to estimate the precipitation and climatic conditions for the project area. The mean annual precipitation from both the stations averages at 740 mm of which 90 % falls within the summer months. The highest rainfall periods occur between November, December and January accounting for 50 % of the annual rainfall, whilst 3 % of the annual rainfall occurs during June, July and August (Figure 1).

The mean monthly evaporation varies from 101 mm (June) to 209 mm (December), with mean annual evaporation at 1945 mm for the Witbank region (Figure 1).

Figure 1: Mean Monthly Rainfall and Evaporation

3.2 Topography and Drainage

The topography of the site has a low relief with level to slightly undulating plains. The majority of the project site is located on the eastern side of the watershed separating the Wilge and Bronkhorstspruit Rivers. The western section of the project delineation is located on the highest point of the watershed with an elevation of approximately 1580 mamsl. The lowest elevation (approximately 1540 mamsl) of the project site occurs along the southern


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and eastern boundary where tributaries to the Wilge River cross the project site. Land use on the project site is dominated by cultivated and livestock farming. Historical and current coal mining activities have or are occurring on neighbouring farm portions to the project area.

The main surface drainage direction from the project site will be towards the Wilge River. The Wilge River and associated tributaries are perennial streams which flow in an overall northerly direction. Minor surface drainage from the western extent of the project area will flow towards the non-perennial Bronkhorstspruit tributary which drains in a northerly direction. This is located within the B20 Drainage Catchment of the Olifants Water Management Area (WMA 02). The quaternary catchment of the site is B20E. The quaternary catchment has been divided into sub-catchments as indicated on Plan 6.

3.3 Geology

The Brakfontein Project is located on the western extent of the Witbank Coalfield, located within the Ecca Group of the Karoo Supergroup.

The Pre-Karoo geology underlying the Witbank Coalfield comprises of the Transvaal Supergroup lithologies and Rooiberg Group felsite. Within the Brakfontein project area, dolomite of the Malmani Subgroup (Transvaal Supergroup) was intersected below the Karoo Supergroup sequence. The Malmani Subgroup carbonate sequence developed under a tidal range of paleo-environments ranging from supra-tidal through intertidal to sub-tidal which results in a variety in chert content, intercalated shales and erosional surfaces (Johnson et al, 2006).

The coal containing Vryheid Formation was deposited directly on the uneven pre-Karoo and Dwyka Group lithologies resulting in variations in thickness of the deposit and pinching out of the formation against paleo-highs. The Dwyka Group sedimentary rocks were deposited in glacial environments and comprise predominantly of tillite. The Vryheid Formation was deposited during deltaic to fluvial events with general upward coarsening cycles comprising of shales, siltstones and sandstones. Northern sequences of the Vryheid Formation contain very coarse grained sandstone deposited by fluvial events. Coal swamps formed in sheltered environments created by the pre-Karoo topography and glacial deposits (Johnson et al, 2006).

The Karoo Supergroup contains extensive dolerite intrusions, which represent the shallow feeder system for the flood basalt eruptions and occur as interconnected networks of dykes and sills (Duncan and Marsh, 2006). These intrusions are important geological structures for diverting and impeding groundwater flow. Sediments in contact with the intrusions become altered by contact metamorphism and are significant for their water bearing properties.

Borehole logs of the newly drilled boreholes are presented in Appendix B. A surface geology map is shown as Plan 7. It is not the intention of the exploration and mining operations to penetrate the pre-Karoo basement during the relative activities but to cease penetration beneath the coal seam of interest.


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3.3.1 Coal Seams

The coal seams within the proposed Brakfontein project prospecting right area are contained within a 100 metre thick succession of the Vryheid formation (Karoo Supergroup) (Figure 2). Four seams (namely, Seam No. 5, 2U and 4L) have been investigated for opencast mining methods whilst two seams (namely Seam No. 2 and 4) are defined as underground mining targets.

Seam No. 5 has a thickness varying between 0.5 to 2 metres, averaging at approximately 1.8 metres.

Seam No. 4 varies from 2.5 to 6.5 metres thick however the seam continuity can be divided into three zones, No. 4 Lower, No. 4 Upper and No. 4 A which are separated by siltstone to mudstone partings. The mining horizon is restricted to the No. 4 Lower Seam where the coal has a quality suitable for power station feedstock. Poor quality coal is attributed to the remaining seams not included in the mining horizon.

Seam No. 2 varies in thickness from 3 to 6.5 metres and contains some of the best quality coal, suitable for the local Eskom market.


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Figure 2: Stratigraphic Column for the Vryheid Formation in the Delmas Area

(Cairncross and Cadle, 1988)

! R

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1

4

2

5

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UNI 1292

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3.4 Aquifers

The natural hydrogeological system within the Witbank Coalfield consists of three superimposed aquifers, namely an upper weathered aquifer, a fractured Karoo aquifer and a fractured basement (pre-Karoo) aquifer (Hodgson and Krantz, 1998).

The aquifers at Brakfontein are simplified and conceptualised to be composed of four units, namely the shallow weathered aquifer, the intermediate fractured Karoo comprising of sandstones, siltstones, shale and coal, the Dwyka tillite and the Malmani dolomite aquifers.

3.4.1 Shallow Weathered Aquifer

The weathered material in the shallow weathered aquifer consists mostly of decomposed and highly weathered coarse grained sandstones, with shales and siltstone. The sustainability of the shallow weathered aquifer is dependent on seasonal recharge from rainfall. The rainwater infiltrates the soil and a portion of it eventually reaches the saturated zone (effective recharge). From the five boreholes drilled around the Brakfontein project the weathered aquifer ranges from 6 to 12 mbgl, averaging at 9 mbgl. The aquifer transmissivity of the weathered material is estimated between 0.5 and 1.5 m²/day (Hodgson and Krantz, 1998).

3.4.2 Fractured Aquifer

The fractured aquifer consists of un-weathered sequences of sandstone, siltstone, shale, carbonaceous shale and coal. The pores within these sediments are too well cemented to allow any significant permeation of water. All groundwater movement is therefore along secondary structures such as fractures, cracks and joints within the sediments. However, not all secondary structures within the fractured aquifer are water-bearing. In general the apertures of water-bearing structures open to flow are very small and have characteristic low hydraulic conductivities.

Of all un-weathered sediments in the fractured aquifer, the coal seam often has the highest hydraulic conductivity.

3.4.3 Dwyka Tillite

The Dwyka tillite forms a hydraulic barrier between the overlying mining activities and the basement aquifer, due to its low hydraulic conductivity. The aquifer permeability of the Dwyka tillite is estimated to be between 0.0002 and 0.0148 m/d (Hodgson and Krantz, 1998). The thickness of this aquifer varies from 0.5 to 30 m thick averaging at 8 m.

3.4.4 Malmani Dolomite Aquifer

The basement aquifer comprises of Malmani dolomites, characterised as part of the chert bearing to chert poor chemically derived sediments of the Chuniespoort Group. The Chuniespoort Group dolomites represent the most important aquifer in South Africa due to the high storage and permeability characteristics of the rock type. The continuity of the dolomite aquifer is interrupted by vertical to sub-vertical geological structures such as dykes


UNI 1292

41

which create low permeability to impermeable compartmental barriers. Dolomitic areas can have high recharge and significant groundwater flow characteristics (Hodgson and Krantz, 1998; and Barnard, 2000).

Unlike most other formations, the groundwater level in dolomitic aquifers does not necessarily follow the topography. More often than not, it occurs as nearly horizontal surface indicative of a low hydraulic gradient and permeable formations (Barnard, 2000).

3.5 Groundwater Levels, Groundwater Flow and Gradient

3.5.1 Groundwater levels

Water levels observed at the Brakfontein site varies between 1535 mamsl (BRABH02) and 1586 mamsl (UNI04). The distribution of the water levels is represented in Figure 3, with the bigger circles indicating highest water level elevation and smaller circles indicating lower water level elevations.

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UNI 1292

43

The Flow direction of the groundwater in the study area correlates fairly well with the surface topography. The Bayesian correlations for pre mining conditions are shown in Figure 4. The water levels observed at the mining area shows a correlation of 79.13% leading to the conclusion that the groundwater flow direction generally mimics the surface topography. However, localised variations may occur as a result of mining activities and groundwater abstraction for agricultural irrigation purposes in some areas.

Figure 4: Bayesian correlation pre-mining

Figure 5 shows the groundwater flow directions as derived from the groundwater level elevation distribution interpolated with the topography.

R² = 0.7913

1530

1540

1550

1560

1570

1580

1590

1530.00 1540.00 1550.00 1560.00 1570.00 1580.00 1590.00 1600.00

To

po

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ma

ms

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Water level elevation (mamsl)

Bayesian correlation


UNI 1292

44

Figure 5: Groundwater contours

3.6 Recharge

Recharge is defined as the process by which water is added from external sources to the zone of saturation of an aquifer, either directly into a formation or indirectly by way of another formation. The percentage recharge to the Karoo aquifer is estimated to be in the order of 1 to 3 % of rainfall (Hodgson and Krantz, 1998). The average rainfall in the area is approximately 740 mm/a which implies that approximately 7.4 to 22.2 mm/a of precipitation contributes to recharge to the groundwater system within the Karoo Supergroup.

The GRDM software data indicates a recharge potential of 41.6 mm/a for the B20E catchment and 43.8 mm/a for the B20A catchment which incorporates the Brakfontein project area. The Malmani dolomites which are present in the area contribute to the increased recharge potential of the catchments.

3.7 Groundwater Quality

Groundwater and surface water samples collected during the hydro-census and from the newly drilled boreholes were submitted to Clean Stream Laboratories for chemical analysis. The results of the chemical analyses are referenced against the South African National


UNI 1292

45

Standards for drinking water (SANS 241:2005) and are given in Table 9. The positions of the boreholes are shown on Plan 3 for the hydro-census results and Plan 4 for the newly drilled boreholes. Laboratory certificates are presented in Appendix C.

Entries in Table 9 colour coded red, exceed the maximum allowable limits, while those in yellow are within the maximum allowable limits. Water quality with constituents exceeding the maximum allowable limits is not recommended for human consumption. The following conclusions can be drawn:

The groundwater and surface water in the area ranges from slightly acidic to slightly alkaline, with low salinity levels;

Water Quality is of acceptable standards for all sites except WILGE 1, UNI 04, UNI 07, BRABH 01 and BRABH 05;

WILGE 1 contains elevated to Class II maximum allowable concentrations of manganese (0.11 mg/l). WILGE 1 is an upstream location from the project area indicating water quality entering the project site. WILGE 1 can indicate contamination from historical and current mines operating south of the Brakfontein project;


UNI07 contains excessive (above Class II maximum allowable) concentrations of fluoride (1.56 mg/l). Presence of fluoride can be found naturally in groundwater or present from anthropogenic contamination. This is the only borehole located on the left of both the faults which can suggest that the source of fluoride is localised to this area by the fault. Whether the source of fluoride is natural or anthropogenic is undermined;


BRABH 05 contains elevated to Class II (maximum allowable) concentrations of manganese (0.21 mg/l). The background manganese concentrations are very low for the area as determined by the other groundwater samples indicating an additional source of manganese is present for this borehole. The source can be natural (intersections with coal layers) or as contamination from historical mine workings.

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pH-Value at 25° C

Conductivity at 25° C in mS/m

Total Dissolved Solids

Calcium as Ca

Magnesium as Mg

Sodium as Na

Potassium as K

Total Alkalinity as CaCO3

Chlorides as Cl

Sulphate as SO4

Nitrate NO3 as N

Fluoride as F

Aluminium as Al

Iron as Fe

Manganese as Mn

Free and Saline Ammonia as N

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5-9

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0 <1

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<50

N/S

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0 70

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0 20

0-40

0 50

-10

0 N

/S

200-

600

400-

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0 1-

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1-1

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1

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1 8.

20

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42.9

7 61

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3.50

25

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186.

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0.

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17

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8.18

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0 19

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56

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1 -0

.01

0.00

0.

33

UN

I09

7.93

53

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00

40.7

5 28

.89

14.2

6 5.

00

159.

00

21.5

0 64

.49

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0.02

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0.

34

UN

I11

8.17

50

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545.

00

25.0

5 14

.53

138.

64

2.87

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0.00

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0.

21

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8.31

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18.1

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130.

44

2.03

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0.

32

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7.59

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00

40.7

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100.

18

1.14

28

1.10

29

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00

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UN

I15

7.17

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12

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2.59

66

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8.70

4.

76

3.93

0.

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09

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7.92

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0.

46

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Fig

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20%

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80%

20%

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60%

80%

20%

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60%

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20%

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BRA

BH 0

1 B

RABH

02

BRA

BH 0

3 B

RABH

04

BRA

BH 0

5 U

NI02

UNI

04 U

NI07

UNI

09 U

NI11

UNI

12 U

NI14

UNI

15 U

NI16

Chl

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Sulphate

Total Alkalinity

Sodium & Potassium

Magnesium

Cal

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Anio

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atio

ns

Pipe

r Dia

gram


UNI 1292

48

Classification diagrams such as Piper diagrams, Durovs or Expanded Durov diagrams, where the relative concentration of species are displayed are useful in understanding the hydro-chemical character of aquifers. The Piper diagram (Figure 6) indicates the regional water type varies from sodium-potassium bicarbonate to calcium-magnesium bicarbonate with a range in sulphate from 5% to 55%. Variability of sulphate and water type is dependent on individual boreholes and no regional distribution trend could be identified.

Two boreholes BRABH 01 and BRABH 03 indicate a calcium-magnesium chloride water type. Furthermore it also suggests a sulphate dominant groundwater however the sulphate anion contribution is below 10%. The chloride percentage controls the placement of these boreholes in the diagram;

Samples UNI 02, UNI 04, UNI 09, UNI 015, UNI 016, BRABH 02, BRABH 04 and BRABH 05 typically indicate freshly recharged (calcium-magnesium bicarbonate) groundwater;

Samples UNI 07, UNI 012 and UNI 014 indicate dynamic groundwater flow (sodium bicarbonate type); and

Sample UNI 011 could indicate dynamic groundwater flow however the contribution of sulphate alters the location on the Piper diagram to indicate a sodium chloride water type.

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Fig

ure

7:

Sc

ho

ell

er

Dia

gra

m f

or

Gro

un

dw

ate

r

0.00

1

0.010.1110100

1000

0.00

1

0.01

0.1

110100

1000

0.1110100

1000

1000

0

0.1110100

1000

1000

0

0.1110100

1000

1000

0

0.1110100

1000

1000

0

0.1110100

1000

1000

0

0.1110100

1000

1000

0

mEq

/lm

g/l

mg/

lm

g/l

mg/

lm

g/l

mg/

lm

Eq/l

BRA

BH 0

1 B

RABH

02

BRA

BH 0

3 B

RABH

04

BRA

BH 0

5 U

NI02

UNI

04 U

NI07

UNI

09 U

NI11

UNI

12 U

NI14

UNI

15 U

NI16

10

T.Al

kS

O4-

-C

l-N

a+M

g++

Ca+

+

Scho

elle

r Dia

gram

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Fig

ure

8:

Sc

ho

ell

er

Dia

gra

m f

or

Su

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ce W

ate

r

0.00

1

0.010.1110100

1000

0.00

1

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0.1

110100

1000

0.1110100

1000

1000

0

0.1110100

1000

1000

0

0.1110100

1000

1000

0

0.1110100

1000

1000

0

0.1110100

1000

1000

0

0.1110100

1000

1000

0

mEq

/lm

g/l

mg/

lm

g/l

mg/

lm

g/l

mg/

lm

Eq/l

WIL

GE1

WIL

GE2

T.Al

kS

O4-

-C

l-N

a+M

g++

Ca+

+

Scho

elle

r Dia

gram


UNI 1292

51

The Schoeller Diagrams given as Figure 7 for groundwater and Figure 8 for surface water results indicates a variety of water quality trends.

The groundwater results indicate no clear trends for the surrounding project area. However, calcium, magnesium and alkalinity appear to be relatively stable showing the least amount of variation between samples and sodium and sulphate indicating the greatest variability.

The surface water results indicates the upstream and downstream samples have almost identical trends with WILGE1 (the upstream sample) showing a more pronounced dip in chloride and peak for sulphate. As WILGE 1 is located immediately downstream of historical mine workings it could indicate a more contaminated trend compared to WILGE 2, which is located further downstream.

3.8 Acid Base Accounting

Geochemical sampling of the available core was undertaken on the 12th June 2012. Core samples were available from exploration boreholes drilled around the project site (Plan 5). The results of twenty samples and two duplicates analysed by Waterlab Laboratory are summarised in Table 10. The Neutralisation Potential Ratio (NPR) versus paste pH for the Brakfontein samples is presented in Figure 9.

Table 10: Summary of ABA results

Core Sample Paste pH

Total

Sulphur (%)

Sulphate

Sulphur (%)

Sulphide

Sulphur (%)

AP

(CaCO3) (kg/t)

NP

(CaCO3) (kg/t)

NNP

(CaCO3) (kg/t) NPR

BN4 S2 4.60 1.43 0.51 0.88 44.69 -1.78 -46.46 0.04 BN4 S4 6.20 1.00 0.42 0.58 31.25 20.11 -11.14 0.64 BN8 S1/S2 6.50 2.26 <0.01 2.26 70.63 4.86 -65.77 0.07 BN8 S4 5.30 0.30 0.06 0.20 9.38 -1.27 -10.64 0.13 BN8 SST 5.20 0.17 0.06 0.11 5.31 -5.35 -10.66 1.01 BN9 S2 6.60 0.91 0.30 0.60 28.44 22.71 -5.73 0.80 BN9 S4 7.30 0.14 0.08 0.05 4.38 -1.11 -5.49 0.25 BN9 SST 6.00 0.99 0.04 0.85 30.94 3.33 -27.61 0.11 BN11 S4 4.10 1.30 0.09 1.10 40.63 -2.80 -43.42 0.07 BN11 SST 5.30 0.14 0.13 <0.01 4.38 0.78 -3.60 0.18 BN11 SST D 5.90 0.14 - - 4.38 -0.76 -5.13 0.17 BN14 S2 4.90 1.75 0.67 1.08 54.69 -2.03 -56.72 0.04 BN14 S4 4.70 0.11 0.05 0.04 3.44 -1.78 -5.21 0.52 BN14 SST 4.00 0.36 0.08 0.28 11.25 -2.80 -14.05 0.25 BN18 S4 5.40 0.16 0.11 0.05 5.00 -3.31 -8.31 0.66 BN18 SST 6.60 <0.01 <0.01 <0.01 0.31 -4.07 -4.38 13.02 BN22 SST 5.40 0.27 <0.01 0.27 8.44 -2.54 -10.98 0.30 BN23 S1/S2 6.10 0.47 0.04 0.43 14.69 -0.50 -15.19 0.03 BN26 S1/S2 6.30 3.84 <0.01 3.23 120.00 0.27 -119.74 0.00 BN26 S4 4.40 0.13 0.10 0.01 4.06 -0.25 -4.31 0.06 BN26 SST 6.20 0.06 0.01 0.01 1.88 -1.01 -2.88 0.54


UNI 1292

52

Core Sample

Paste

pH

Total Sulphur

(%)

Sulphate Sulphur

(%)

Sulphide Sulphur

(%)

AP (CaCO3)

(kg/t)

NP (CaCO3)

(kg/t)

NNP (CaCO3)

(kg/t) NPR

BN26 SST D 6.30 0.06 - - 1.88 0.01 -1.87 0.01 BN29 S4 4.00 1.35 0.54 0.78 42.19 -2.54 -44.73 0.06 BN29 SST 5.30 0.60 0.37 0.19 18.75 -2.03 -20.78 0.11

BN11 SST D and BN26 SST D are laboratory selected duplicates. An additional two samples, selected randomly, were sent to the laboratory as duplicates. The duplicate identities are BN4 S2 (for sample BN29 S4) and BN4 S4 (for sample BN9 S2) and the results are isolated in Table 11.

The laboratory selected duplicates indicate similar results as sample was processed prior to analyses. The submitted duplicates show a greater degree of variation as sample was split after crushing.

Table 11: ABA Duplicates

Core Sample Paste pH

Total Sulphur

Sulphate Sulphur

Sulphide Sulphur

AP (CaCO3)

NP (CaCO3)

NNP (CaCO3) NPR

BN4 S2 4.60 1.43 0.51 0.88 44.69 -1.78 -46.46 0.04

BN29 SST 5.30 0.60 0.37 0.19 18.75 -2.03 -20.78 0.11

BN4 S4 6.20 1.00 0.42 0.58 31.25 20.11 -11.14 0.64

BN9 S2 6.60 0.91 0.30 0.60 28.44 22.71 -5.73 0.80

BN11 SST 5.30 0.14 0.13 <0.01 4.38 0.78 -3.60 0.18

BN11 SST D 5.90 0.14 - - 4.38 -0.76 -5.13 0.17

BN26 SST 6.20 0.06 0.01 0.01 1.88 -1.01 -2.88 0.54

BN26 SST D 6.30 0.06 - - 1.88 0.01 -1.87 0.01

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Fig

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NP

R v

s p

H


UNI 1292

54

The following conclusions are drawn for the ABA characterisation:

The average paste pH for all samples is slightly acidic (pH 5.5) with the range varying from pH 4 to 7.3;

All samples are potentially acid generating with negative Net Neutralising Potentials (NNP);

In general the S1/S2 sample taken from contacts of the upper coal seams (seams 1 and 2) are more acid generating than the lower coal seam (seam 4) and the interburden (identified by SST);

The sulphur species determination is broken down into total sulphur, sulphate and sulphide;

The average Neutralising Potential (NP) is 0.67 kg/t (CaCO3)

The average Acid Potential (AP) is 23.37 kg/t (CaCO3)

The average NNP is -22.70 kg/t (CaCO3)

ABA is based solely on the static tests and does not indicate the long term acid generation potential of the materials. Activities which change the weathering conditions of the material or relative surface area exposure (finer particles will have a higher exposure surface) of acid generating and neutralising minerals, can alter the results in either a positive or negative manner.

The resultant impact of acid drainage is the leaching of heavy metals and salts into the surrounding surface and groundwater environments.

3.9 Aquifer Classification

The classification scheme (Parsons and Conrad, 1998) was created for strategic purposes as it allows the grouping of aquifer areas into types according to their associated supply potential, water quality and local importance as a resource (Table 12).

The term vulnerability as used in the Parsons and Conrad, 1998 classification is defined as the tendency or likelihood for contamination to reach a specified position in the groundwater after introduction at some location above the upper most aquifer. The susceptibility of an aquifer is defined as a qualitative measure of the relative ease with which a groundwater body can be potentially contaminated by anthropogenic activities and includes both aquifer vulnerability and the relative importance of the aquifer in terms of its classification.

Table 12: Aquifer Classification Scheme

Aquifer

System

Defined by Parsons and Conrad (1998) Defined by DWAF Min Requirements

(1998)

Sole Source Aquifer

An aquifer which is used to supply 50 % or more of domestic water for a given area, and for which there are no reasonably available alternative sources should the aquifer be impacted upon or depleted. Aquifer yields and natural water quality are immaterial.

An aquifer, which is used to supply 50% or more of urban domestic water for a given area for which there are no reasonably available alternative sources should this aquifer be impacted upon or depleted.


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Major Aquifer

High permeable formations usually with a known or probable presence of significant fracturing. They may be highly productive and able to support large abstractions for public supply and other purposes. Water quality is generally very good (<150 mS/m).

High yielding aquifer (5-20 L/s) of acceptable water quality.

Minor Aquifer

These can be fractured or potentially fractured rocks, which do not have a high primary permeability or other formations of variable permeability. Aquifer extent may be limited and water quality variable. Although these aquifers seldom produce large quantities of water, they are important both for local supplies and in supplying baseflow for rivers.

Moderately yielding aquifer (1-5 L/s) of acceptable quality or high yielding aquifer (5-20 L/s) of poor quality water.

Non-Aquifer

These are formations with negligible permeability that are generally regarded as not containing groundwater in exploitable quantities. Water quality may also be such that it renders the aquifer as unusable. However, groundwater flow through such rocks, although imperceptible, does take place, and need to be considered when assessing the risk associated with persistent pollutants.

Insignificantly yielding aquifer (< 1 L/s) of good quality water or moderately yielding aquifer (1-5 L/s) of poor quality or aquifer which will never be utilised for water supply and which will not contaminate other aquifers.

Special Aquifer

An aquifer designated as such by the Minister of Water Affairs, after due process.

An aquifer designated as such by the Minister of Water Affairs, after due process.

According to the regional aquifer classification map of South Africa, the dolomite aquifer located at Delmas has been identified as a sole source aquifer system with good quality (<300 mg/L TDS) with a high vulnerability and high susceptibility to contamination. The surrounding Karoo aquifer has been identified as a minor aquifer also with good quality (<300 mg/L TDS) with a moderate vulnerability and a medium susceptibility to contamination.

Based on the underlying hydrogeology of the project area, and the corresponding aquifer test results and analyses, the aquifers have been classified according to Parsons and

system as follows:

Weathered Aquifer Minor Aquifer Fractured Karoo Aquifer Minor Aquifer Dwyka Tillite Aquifer Non Aquifer Basement Karst Aquifer Major Aquifer

3.10 Groundwater Use

Groundwater use in and around the project area is predominantly for livestock watering, crop irrigation and domestic purposes. There are operational mining projects currently neighbouring the Brakfontein project which could be dewatering their opencast and underground workings.


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The harvest potential map of South Africa indicates that 15 000 25 000 m3/km2/annum can be abstracted sustainably from the Karoo aquifers and 25 000 50 000 m3/km2/annum sustainably abstracted from the Malmani dolomites around the Delmas area.

The factor restricting the harvest potential of the Karoo aquifers around the Delmas area is the effective storage volume. Recharge occurs regularly but low storage of the aquifer prevents absorption of the recharge into the aquifer. The limiting factor is related to how much groundwater can be stored during the wet season to accommodate abstraction in the dry season.

The factor restricting the harvest potential of the Malmani dolomite aquifer is the volume of annual recharge. The dolomite aquifer storage capabilities therefore exceed the annual volume of recharge supplied to it.

The GRDM software data indicates that the current groundwater use is 1.52 million m3/a for the B20A catchment and 0.51 million m3/a for the B20E catchment in which the project area falls. The exploitation potential is set at 12 million m3/a (B20A) and 7 million m3/a (B20E), which indicates that the groundwater resource is under-utilized.

3.10.1 Baseflow to Streams Ecological Receptors

Baseflow is the part of stream that is derived from groundwater and shallow subsurface storage. During the dry season, the stream flow is typically composed entirely of baseflow. Groundwater dependant ecosystems (GDEs) are ecosystems which have their species composition and their natural ecological processes determined by groundwater.

Data sourced from the GRDM software (Table 13) indicates that the streams are constantly flowing with approximately 0.3 % of groundwater recharge contributing to baseflow in rivers per annum. Both catchments indicate that approximately 6.8 million m3 of groundwater is contributed to streams per year.

Table 13: Baseflow to Streams

Resource Unit

Area (km2)

Mean Annual Rainfall (mm/a)

Mean Annual Runoff (mm/a)

No flow (%)

Recharge (mm/a)

Baseflow1 (mm/a)

Baseflow2 (million m3/a)

B20A 574.3 661 38 0 43.83 12 6.89 B20E 619.9 657 34 0 41.67 11 6.81

3.11 Mine Plan

It is proposed that Brakfontein reserves will be accessed through five opencast pits and one underground section. The planned life-of-mine makes allowance for one year for the construction phase followed by a 29 year operational phase broken down as follows:

1 Baseflow (mm/a) indicates groundwater contribution to stream flow 2 Baseflow (million m3/a) indicates groundwater contribution to stream flow for the entire catchment


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Opencast mineable resource (31.4 Mt ROM)/1.44 Mtpa ROM = 21.8 years

Underground mineable resource (5.6 Mt ROM)/0.72 Mtpa ROM = 7.8 years

Resulting in a total life-of-mine of 29.6 years

4 NUMERICAL MODELLING

4.1 Steady state model

Prior to considering and implementing mining and dewatering activities, a pre-mining steady state groundwater flow model was set-up and calibrated. The objective of the steady state model was to simulate the current groundwater system in the region prior to commencement of mining activities. Mining impacts on the groundwater level is then determined by comparing the transient state results with the steady state water levels.

The steady state model is calibrated with the current groundwater level measurements obtained from the Digby Wells field investigation during April, May and June 2012.

4.1.1 Model setup

During model setup, the conceptual model is translated into a numerical model. This stage entails selecting the model domain, definition of model boundary conditions, discretizing the data spatially and over time, defining the initial conditions, selecting the aquifer type, and preparing the model input data. The above conditions together with the input data are used to simulate the groundwater flow in the model domain for pre-mining impact conditions, i.e. steady state conditions.

4.1.2 Selecting a Model domain and Defining Model Boundary Conditions

The model domain is specifically selected to assess the regional groundwater flow conditions on a catchment scale and incorporates the local groundwater flow conditions in and around the proposed mining area. The model domain (Figure 10) is irregularly shaped defined by the minimum and maximum coordinates listed in Table 14. The model domain is defined by the natural water divide (local catchment boundaries).

Table 14: Boundary coordinates of the model domain

X minimum X Maximum Y Minimum Y Maximum

-2680 -20080 -2890350 -2907950

The boundaries and conditions assigned to the model domain are illustrated in Figure 10 and described as follow:

The perennial Wilge River and the major tributaries is simulated using the River Package of PMWIN;


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The non-perennial rivers tributaries is simulated using the Drain Package of PMWIN;

Farm dams simulated using the reservoir package of PMWIN; and

No flow boundaries are assigned to west and the east of the model domain representing the water divide of the greater catchment.

Figure 10: Numerical model domain

4.1.3 Top/bottom of aquifer

The elevation data was interpolated into the finite difference cells using the Field Interpolator package in PMWIN and the Kriging method. This was then imported as top of the model


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domain. The following assumptions have been made with regard to the aquifer thickness in the area of interest:

The bottom of the top weathered aquifer was set 14 m below the surface elevation;

The bottom of the fractured aquifer was set 36 m below the weathered aquifer; and

The bottom of the third layer (Dwyka tillite) was set at 10 m below this elevation, resulting in a total model thickness of 60 m.

4.1.4 Model Mesh

A rectangular mesh is generated over the model domain, consisting of 88 rows and 88 columns (Figure 10). The mesh is refined in the vicinity of the proposed new mining area (cell size is 50 x 50 m in length). Although a smaller grid size may results in prolonged running time, it is important to refine the model over the investigation site, so that the groundwater gradient can be calculated more accurately. Cell dimensions of the outside part of the model domain are set at 200 x 200 m.

4.1.5 Layer type

The layer types applied in the model are as follow:

The weathered aquifer is modelled as layer type 2: Confined/unconfined, transmissivity stay constant;

The fractured aquifer is modelled as layer type 2: Confined/unconfined, transmissivity stay constant; and

The bottom aquifer is modelled as layer type 2: Confined/unconfined, transmissivity stay constant.

4.1.6 Hydraulic Properties applied for the flow model

The parameters described below were applied to the model domain:

4.1.6.1 Recharge

The natural recharge (the portion of rainfall that infiltrates the ground and eventually replenishes the groundwater reservoir) is not expected to be uniform across the model domain. A lower recharge is assigned to the higher lying topographical areas, where water is more likely to run off to lower lying areas, than to infiltrate into the subsurface.

The percentage recharge to this aquifer is estimated to be in the order of 1-3% of rainfall (Hodgson & Krantz, 1988). The average rainfall in the area is approximately 740 mm/a. This implies that approximately 7.4 mm/a to 22.2 mm/a of precipitation recharges the groundwater system. The model calibration was used to estimate a recharge value of 0.5% of MAP in the higher lying areas, where run-off drains most of the rainfall that fall on the surface and 1.2% of MAP in the lower lying areas as indicated in Table 15 and Figure 11 below.

Table 15: Recharge zones


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Recharge Zone Recharge in m Recharge as % of MAP

Z1 1.0137E-05 0.5

Z2 2.43288E-05 1.2

Figure 11: Recharge zones

4.1.6.2 Transmissivity

The transmissivity values (T-value) obtained from the aquifer tests and existing information from research in the Witbank Coal fields were applied in the model domain (Figure 12 - Figure 13 and Tables 5 - 6) to simulate the regional groundwater flow system. The final T-value utilised could reasonably differ from the data obtained from aquifer test data as part of the model calibration so that the observed and simulated water heads can be correlated.

Z1

Z2


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An assumption is made that the Ogies dyke has a low transmissivity, but this has not been confirmed with drilling and aquifer testing during this investigation.

Figure 12: Transmissivity zones calibrated: Layer 1

Table 16: Transmissivity values: Layer 1

Transmissivity Zone Transmissivity value m2/d Description

T1 2.5 Weathered Karoo aquifer

T2 29 Dolomite pocket

T3 0.1 Ogies dyke

T2

T1

T3


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Figure 13: Transmissivity zones calibrated: Layer 2

Table 17: Transmissivity values: Layer 2

Transmissivity Zone Transmissivity value m2/d Description

T1 1.7 Fractured Karoo Aquifer

T2 21 Dolomite pocket

T3 0.1 Ogies dyke

Only one transmissivity value of 0.2 m2/d was assigned to Layer 3 which represents the Dwyka tillite underlying the Karoo aquifers.

T1

T2

T3


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4.1.7 Steady state model calibration

The model is calibrated by varying model input data over realistic ranges of values until a satisfactory match between simulated and observed data is reproduced. In this modelling exercise, the most uncertain parameters are assumed to be:

The spatial distribution and volume of annual natural recharge;

Transmissivity of the Ogies dyke; and

Regional inflow/outflow of groundwater into/out of the model domain.

Since the recharge and transmissivity are dependent on each other via the measured heads, the model was not calibrated by changing the T-value and recharge simultaneously. The T-value was calibrated based on the aquifer test data first, while the recharge value was adjusted after applying calculated T-values observed from aquifer test data.

4.1.8 Observation boreholes

A total number of eight observation boreholes (Table 18) are used for the steady state model calibration (Figure 10). All of the water level measurements were made during the Digby Wells field investigation conducted from April to June 2012. These boreholes are relatively uniformly distributed over the proposed mining area and sub-catchment, assisting calibration. On a more regional level, up to date water level measurements were lacking to assist model calibration.

Table 18: Boreholes used for steady state model calibration

Site Name Y coordinate3

X coordinate

Z coordinate

Water level (mbgl)

WL-Elevation

BRABH 02 -26.194300 28.866600 1542.00 5.53 1536.48

BRABH 01 -26.207400 28.874500 1549.00 6.40 1542.60

BRABH 04 -26.208100 28.846210 1563.00 17.16 1545.84

BRABH 03 -26.204900 28.859730 1554.00 5.61 1548.39

UNI17 -26.201426 28.842785 1556.00 2.44 1553.56

BRABH 05 -26.216300 28.850050 1577.00 23.20 1553.80

UNI12 -26.238239 28.876364 1565.00 5.83 1559.18

UNI13 -26.235361 28.873974 1562.00 2.73 1559.27

After the hydraulic properties of the various geological units were adjusted within a reasonable range, a correlation of 93.96% was obtained between the simulated and observed groundwater elevation (Figure 14).

3 Coordinates in Geographic degrees, WGS 84 projection


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In Figure 15 a graph of the differences between observed and calculated head values (residuals) is plotted. The residuals (difference between calculated and observed groundwater level) are calculated between -3.095 m (UNI13) and 3.089 m (BRABH2). On average the calculated groundwater levels are 0.15 m above the levels measured in the field. The overall simulated heads coincide very well with the actual heads, confirming the model as a suitable predictive tool to simulate the aquifer system in the project area.

Figure 14: Correlation between the observed and simulated heads

Figure 15: Line chart of observed and simulated heads

R² = 0.9396

1535

1540

1545

1550

1555

1560

1565

1535 1540 1545 1550 1555 1560 1565

1530

1535

1540

1545

1550

1555

1560

1565

BRABH 02 BRABH 01 BRABH 03 UNI17 BRABH 05 UNI12 UNI13

Observed Simulated


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4.1.9 Sensitivity analysis

The sensitivity of the model was evaluated tweaking the calibrated recharge and transmissivity values by factors between 0.1 and 10. As depicted in Figure 16, the model is more sensitive to transmissivity in layer one (T value L1) than recharge and transmissivity in layer two (T value L2).

Figure 16: Model sensitivity to recharge and transmissivity

4.2 Transient groundwater flow model

The impact of mine dewatering is computed in a transient model containing different stress periods in order to simulate changes related to model parameters with time.

4.2.1 Mine dewatering

Mine dewatering is simulated by applying drains to the mining areas. These drain cells pecified elevation, representing the pit floor elevation. The

drain cell elevations were incrementally changed, representing the open development over time. A one year mine increment plan was made available to Digby Wells.

4.2.2 Stress Periods and Time Steps

The time increments for the mine operational period, 20 year life of mine were divided into 20 periods with a period length of 360 days consisting of 12 time steps each.

0

50

100

150

200

250

300

0.1 1 10Abso

lute

val

ue o

f mea

n re

sidu

al G

roun

dwat

er le

vel

(m)

Transmissivit and recharge factor

Sensitivity analysis

T value L1

T value L2

Recharge


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4.2.3 Transient model

4.2.3.1 Aquifer Storage

The storativity S represents the amount of water being released from or stored in storage per unit of volume in an aquifer, per unit change in head (Kruseman & de Ridder, 1994). Under confined conditions, water is stored or released due to the compressibility of water and the aquifer matrix. In unconfined conditions, specific yield is the term used for storage and is defined as the water released from a water bearing material by gravity drainage (Schwartz & Zang, 2003). Specific yield releases more water per aquifer unit and drawdown, compared to the specific storage coefficient. Aquifer storage values implemented in the model were derived from literature and are listed in Table 19.

Table 19: Aquifer storage values

Parameter Value

Specific storage 0.0001

Specific yield 0.25

4.2.3.2 Solute Transport Model

The primary mechanisms that control the transport of solutes (contaminants) in porous aquifers are advection and dispersion. Advection is mass transport due to the flow of groundwater in which the mass is dissolved. Groundwater and dissolved solid mass will move at the same rate and in the same direction (Schwarz & Zuang, 2003). Dispersion is a process of mixing that causes a zone of mixing to develop between a fluid in one composition that is adjacent to or being displaced by a fluid with a different composition.

Solute Transport Advection and Dispersion

Sulphate was chosen as the contaminant to be modelled and is transported via advection and dispersion. It represents the maximum advance rate of contamination from the sources.

Dispersivity and Diffusion

No field measurements are available on site for the dispersivity. Generally, the longitudinal dispersivity is about 0.1 of the travel distance of the plume and the transversal dispersivity is about 0.1 of the longitudinal dispersivity. The higher the dispersivity, the smaller the maximum concentration of the contaminant since dispersion causes a spreading of the plume over a larger area.

Effective Porosity

The effective porosity of a sediment or rock is the ratio of volume of the interconnected pores/fractures to the total volume of the soil or rock. Effective porosity is more closely related to the flow of groundwater in a medium than total porosity.


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4.2.3.3 Source location and input concentration

Transport modelling requires an input source concentration and the period during which the source contributed to the groundwater contamination in order to accurately simulate contaminant transport over time.

In Table 20 the contaminant sources and the anticipated start of contamination is listed. A constant input concentration of 100% was assumed for all the discard dumps from the beginning of contamination until year 20, the end of life of mine. The location of the contaminant sources are shown in Figure 17.

Table 20: Contaminant Sources and Begin of Contamination as Implemented in Solute

Transport Model

Feature Input Concentration

Discard OC 1 and 2 100%

Discard OC 3 100%

Discard OC 4 100%

Discard OC 5 100%


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Figure 17: Location of Modelled Contaminant Sources

4.3 Groundwater modelling scenarios

The potential impact of the proposed mining activities on the groundwater environment has to be qualified, using the baseline geohydrological information and calibrated numerical flow and transport model.

The numerical model has been used to simulate the impacts of the open cast areas, underground mine and on groundwater receptors. The scenarios modelled include:



Discard

OC 1 & 2

Discard

OC 5

Discard

OC 5


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4.4 Summary of modelling results

4.4.1 Groundwater balance

Mine dewatering will have an impact on the groundwater volumes available in the aquifers surrounding the proposed mine area.

As the opencast pit and underground mining areas develop, the zone of influence of the groundwater level drawdown will migrate and expand as the groundwater system attempts to retain a state of equilibrium that is continuously disturbed by the on-going mine dewatering.

Initially, groundwater levels within the opencast pit areas will be drawn down to the pit floor elevation causing groundwater flow directions to be centred towards the pit area. The groundwater flow gradients towards the pit area will increase, thereby increasing the groundwater flow velocities. With the development of the additional opencast pits and underground region, and concurrent rehabilitation, groundwater flow will be directed toward the next opencast pits to be mined and the proposed underground mining area. Finally all groundwater flow will be directed towards the underground area due to on-going dewatering, and rehabilitation of opencast pits. This will continue until the final year of the life of mine.

Due to the disturbed nature of the material used for rehabilitation the transmissivity of the rehabilitated areas will be higher than that of the surrounding un-mined rock material. This will allow for increased recharge into the recently rehabilitated material compared to the surrounding un-mined areas which will increase the rate of rise of the groundwater level in the rehabilitated material. This artificially increased recharge rate can also lead to increased dewatering requirements as the recharged water seeps from the rehabilitated zone into the active mine voids.

The predicted inflow rates for the opencast pits and underground mining over the LoM are shown in Table 21. The calculations are influenced by the storage coefficients and specific yields used in the simulations. Best estimates of storage as calculated from the aquifer test data, as well as values obtained from literature in similar environments were used. However, it has to be cautioned that there is some level of uncertainty around the storage values used which could impact the level of confidence of the calculations. Total predicted inflow rates at the proposed Brakfontein mine will range from a minimum of 6.39 m3/d calculated for Year 12 to a maximum of 23.16 m3/d calculated for Year 6.

Table 21: Groundwater inflow rates to mining areas (m3/d)


1 1 272 1 272 14.72

2 709 420 1 129 13.07

3 860 428 1 288 14.91

4 639 1 164 1 803 20.87


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5 663 1 172 1 835 21.23

6 637 1364 2 001 23.16

7 522 1285 1 807 20.91

8 542 798 1 340 15.51

9 1741.5 1 742 20.16

10 749 749 8.67

11 765.5 766 8.86

12 552 552 6.39

13 556.5 557 6.44

14 589 589 6.82

15 825 825 9.55

16 618 618 7.15

17 854.5 855 9.89

18 921.5 922 10.67

19 938.5 939 10.86

20 1245 1 245 14.41

4.4.2 Dewatering cone of influence

On-going dewatering inevitably causes lowering of groundwater levels surrounding the mining area. The extent of the dewatering cone was modelled for the period of life of mine and is displayed after 5 and then 10 year intervals in Figure 18 to Figure 20 below. Privately owned boreholes that potentially could be impacted on are listed in Table 22.

The model qualified and delineated the groundwater drawdown cone (zone in which the groundwater level is lowered as a result of abstraction) during mine dewatering over time. During the operational phase the cone of depression extends approximately 1100m to the south, 300 m to the west and 500m to the north and east of OC 3, 4 and 5, and approximately 400 500m in all directions from OC 1 and 2. Upon mine closure, pumping of


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water from the mining pit will cease and water levels will recover to pre mining levels over time. No decant from the pit is expected after closure.

Table 22: Privately owned boreholes that could potentially be impacted by dewatering

Borehole Name Owner Use

UNI 01 Contact was not made with Owner Uknown

UNI 10 Pieter Combrink Domestic and stock watering

UNI 11 Pieter Combrink Domestic and stock watering

UNI15 FA Venter Domestic and stock watering

UNI 16 FA Venter Domestic and stock watering


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Figure 18: Mine dewatering cone of influence year 5


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4.4.3 Groundwater quality

Groundwater flowing into the mine workings (opencast pits) will be contaminated due to the mining activities during operation of the mine and post closure groundwater recharging into the pit lake may result in contamination of the surrounding aquifer.

The potential of ARD leachate from the plant, workshop areas and ore stock piles and storm water runoff from dirty areas could lead to groundwater contamination if not contained and managed properly in the pollution control and storm water dams. It is preferred that these dams should be lined in order to prevent seepage of polluted water into the underlying aquifer.

Leachate with elevated salt and metal concentration is likely to leach from the proposed Discard dumps and infiltrate into the groundwater system, resulting in groundwater contamination. Figure 21 displays the predicted contaminant plumes at the end of LoM. Engineering design and storm water management measures can have a minimising effect on the impacts.

Some of the groundwater quality impacts such as leachate from the WRD will remain negative for a period after mining ceased, before the improvement in water quality will start to improve and return to pre mining conditions. Figure 22 displays the predicted contaminant plumes 20 years post closure.

Seepage from the discard dumps is likely to have elevated salt load consisting predominantly of high TDS, SO4 and Ca concentrations. The results from the acid base accounting tests suggest that the waste rock material is likely to have a net potential to generate acid mine drainage.

Groundwater numerical modelling predict that seepage water quality diluted to 5% of the input concentration of 100% is likely to migrate up to between 150m and 300m from the

Groundwater users in the vicinity of the Discard dumps are the farmers as listed in Table 1. No private boreholes are likely to be impacted.


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% Concentration 100 % 5 %

Figure 21: Groundwater pollution plume from the discard dumps at end of life of mine


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% Concentration 100 % 5 %

Figure 22: Groundwater pollution plume from the discard dumps 20 years after

closure


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5 IMPACT ASSESSMENT

Activities which might potentially have an impact on the groundwater regime are discussed in the following sub sections. A description of the impacts of each activity is given and rated based on previous experience in similar circumstances and the results of the groundwater investigation.

5.1 Construction Phase

Activity 1: Site Clearing, Removal of topsoil & vegetation

Description:

Site clearing and removal of topsoil, may lead to ponding of surface water in the cleared areas during the wet season and potentially lead to increased infiltration to the aquifers.

Oil and lubricants used in machinery during the construction may accidentally spill and pose a possible threat to groundwater. Due to the short exposure and small scale of these possible spills, the impacts will be negligible during the construction phase.

Impact assessment:

Parameter Description Rating

Duration Immediate 1

Extent Very limited 1

Severity Low level 1

Probability Probable 4

Significance Negligible 12

Activity 2: Construction of any surface infrastructure e.g. haul roads, pipes, storm water diversion berms (including transportation of materials & stockpiling)

Description:

Oil or fuel spillages from construction machinery may collect in the soils. During rainfall events, hydrocarbon compounds from oils and fuel in the soils may migrate to the subsurface water bodies with water infiltrating through these polluted areas. Due to the short exposure and small scale of these possible spills, the impacts will be negligible during the construction phase.


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Impact assessment:


Duration Short term 2


Severity Low level 1



Activity 3: Blasting and development of initial box-cut for mining (incl. stockpiling from initial cuts).

Description:

Blasting activities may impact negatively on the groundwater quality if significant amounts of explosive are spilled or incompletely detonated. The chemical residues in the form of NH4 and NO3 may potentially leach to the groundwater table. Due to the short exposure and small scale of these possible spills, the impacts will be negligible during the construction phase.

Impact assessment:


Duration Short term 2

Extent Limited 2

Severity Moderate 3

Probability Low Probability 3


Activity 4: Temporary storage of hazardous product (fuel, explosives) and waste or sewage.

Description:

The storage of hazardous products may have potential negative effects on ground-water quality should there be a spillage/leaks that could infiltrate through the soils to reach the groundwater table. Due to the short exposure and small scale of these possible spills, the impacts will be negligible during the construction phase.


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Impact assessment:




Severity Moderate 3

Probability Rare 2


5.2 Operational Phase

Activity 5: Removal of overburden and backfilling when possible (including drilling/blasting hard overburden & stockpiling)

Description:

Rainwater infiltrating through the overburden stockpiles and/or backfilled material and the underlying soils into the groundwater environment could pollute the aquifers, by means of an increased salt load and metals. Acid base accounting tests completed during this investigation indicate a net acid potential in all samples analysed.

Impact assessment:


Duration Permanent Mitigated 6

Extent Local 3

Severity Very serious/Long term 5

Probability High probability 6

Significance Moderate 84

Activity 6: Use and maintenance of haul roads (incl. transportation of coal to washing plant)

Description:

Oil/fuel spillages or coal residue originating from mining machinery and vehicles may collect in the soils. During rainfall events, hydrocarbon compounds from oils and fuel in the soils may migrate to the subsurface water bodies with water infiltrating through these polluted areas.


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Impact assessment:


Duration Project life 5

Extent Municipal area 4

Severity Moderate/short term 3

Probability Likely 5

Significance Minor 60

Activity 7: Removal of coal (mining process) and ROM coal Stockpile

Description:

The removal of coal will lead to a decrease in water level as water flows into the opencast pit. The impact of the proposed mine on regional groundwater resources and users have been qualified using the numerical groundwater model. The model qualified and delineated the groundwater drawdown cone (zone in which the groundwater level is lowered as a result of abstraction) during mine dewatering over time. During the operational phase the cone of depression extends approximately 1100m to the south, 300 m to the west and 500m to the north and east of OC 3, 4 and 5, and approximately 400 500m in all directions from OC 1 and 2 (Figure 20)

Impact assessment:


Duration Permanent mitigated 6

Extent Local 3

Severity Very Serious/Long terms 5




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Activity 8: Water use & storage on site (incl. screening & washing, PCD)

Description:

Storage of water in unlined dams or facilities will lead to an increased infiltration to the underground aquifers and thereby increasing the aquifer recharge. Should this water be polluted water from e.g. the PCD it is likely to recharge the aquifer with polluted water.

Impact assessment:



Extent Local 3

Severity Very serious/Long term 5



Activity 9: Storage, handling and treatment of hazardous products (fuel, explosives, oil) and waste activities (Mine waste discard, sewage)

Description:

The storage of hazardous products and mine waste material such as sewage may have a potential negative effect on ground-water quality should there be a spillage/leaks that could infiltrate through the soils to reach the groundwater table.

Seepage from the discard dumps is likely to have elevated salt load consisting predominantly of high TDS, SO4 and Ca concentrations. The results from the acid base accounting tests suggest that the waste rock material is likely to have a net potential to generate acid mine drainage.

Groundwater numerical modelling predict that seepage water quality diluted to 5% of the input concentration of 100% is likely to migrate up to between 100m and 150m from the discard dump footprint.


UNI 1292

83

Impact assessment:



Extent Local 3

Severity Very serious/long term 5

Probability Certain 7


Activity 10: Concurrent replacement of overburden, topsoil and re-vegetation

Description:

Replacement of overburden in the opencast mining areas will lead to an increase in infiltration and subsequently to aquifer recharge. This will occur even after topsoil placement and re-vegetation, due to an increase in porosity that occurred compared to baseline conditions.

Rainwater infiltrating through the overburden material associated with an increase in the availability of oxygen may increase the potential for acid generation and pollution of the aquifers; however it is still better to replace overburden and topsoil and establish new vegetation than not doing it. The on-going backfilling and rehabilitation result in a lower environmental impact than not implementing such measures. During the operational phase the water flow will be towards the opencast mining pit, from where the water will be pumped and reused in the coal wash plant.

Impact assessment:


Duration Permanent/mitigated 6

Extent Local 3

Severity Very serious/long term 5

Probability Certain 7



UNI 1292

84

5.3 Decommissioning Phase

Activity 11: Demolition & Removal of all infrastructures (incl. transportation off site)

Description:

Oil or fuel spillages from demolition machinery may collect in the soils. During rainfall events, hydrocarbon compounds from oils and fuel in the soils may migrate to the subsurface water bodies with water infiltrating through these polluted areas.

Impact assessment:



Extent Local 3

Severity Minor 2

Probability Low probability 3


Activity 12: Rehabilitation (spreading soil, re-vegetation and contouring/profiling)

Description:

Rehabilitation should reduce the potential for acid mine drainage formation from mining activities and have a positive impact on the recovery of the groundwater quality.

Impact assessment:


Duration Permanent/Mitigated 6

Extent Local 3

Severity Moderate +/ medium term 4




UNI 1292

85

Activity 13: Installation of post closure water management infrastructure

Description:

Oil or fuel spillages from construction machinery may collect in the soils. During rainfall events, hydrocarbon compounds from oils and fuel in the soils may migrate to the subsurface water bodies with water infiltrating through these polluted areas.

Impact assessment:



Extent Limited 2

Severity Minor 2

Probability Rare/Improbable 2


Activity 14: Monitoring and decommissioning

Description:

Deteriorating negative impacts on the groundwater environment could be detected and additional mitigation measures can be implemented to reduce the severity of the impact or even prevent it from re-occurring.

Impact assessment:



Extent Local 3

Severity Limited/Low significance 1




UNI 1292

86

Activity 15: Storage, handling and treatment of hazardous material

Description:

The storage and handling of hazardous products may have potential negative effects on ground-water quality should there be a spillage/leaks that could infiltrate through the soils to reach the groundwater table.

Impact assessment:




Severity Moderate 3

Probability Highly unlikely 1


Activity 16: Post closure monitoring and rehabilitation

Description:

Deteriorating negative impacts on the groundwater environment could be detected and additional mitigation measures can be implemented to reduce the severity of the impact or even prevent it from re-occurring.

Rehabilitation should reduce the potential for acid mine drainage formation from mining activities and have a positive impact on the recovery of the groundwater quality.

Impact assessment:


Duration Permanent/Mitigated 6

Extent Local 3

Severity Moderate +/ medium term 4




UNI 1292

87

6 CUMULATIVE IMPACTS

The proposed project area is located close to existing mines and commercial agricultural activities. In the long term, the cumulative impacts of the proposed and existing activities could result in increased negative effects on the groundwater regime.

The following cumulative impacts of concern could include:

Further deterioration of groundwater quality; and

An increase in acid mine drainage and associated decant post closure.

7 MITIGATION MEASURES AND MANAGEMENT OPTIONS

The Environmental Management Plan (EMP) has been described according to the project activities in order to provide an understanding of what objectives and recommended management measures are required to minimise the environmental impacts arising from these activities. The management measures are described in Table 23 below.

Hyd

roge

olog

ical

Ass

essm

ent f

or th

e B

rakf

onte

in E

IA

UN

I 129

2

88

Ta

ble

23

: M

itig

ati

on

an

d m

an

ag

em

en

t m

ea

su

res

Ac

tivit

y

As

pect

Ob

jecti

ve

s

Mit

igati

on

/ M

an

ag

em

en

t

measu

re

Fre

qu

en

cy

of

mit

igati

on

Le

ga

l

req

uir

em

en

ts

Reco

mm

en

ded

acti

on

pla

ns

Tim

ing

of

imp

lem

en

tati

on

Esti

mate

d

Co

st

Resp

on

sib

le

pers

on

1.

Rem

oval

of

tops

oil

Gro

und-

wat

er

Pre

vent

/con

tain

po

ssib

le

hydr

ocar

bon

spilla

ges

A

dher

e to

traf

fic ru

les

M

aint

ain

vehi

cles

on

a re

gula

r bas

is

M

ake

use

of o

il pa

ns

in/u

nder

veh

icle

s

Con

tinuo

usly

Im

plem

ent t

raffi

c ru

les

and

train

dr

iver

s to

und

erst

and

the

rule

s

Im

plem

ent v

ehic

le m

aint

enan

ce

sche

dule

In

stal

l oil

colle

ctio

n pa

ns

in/u

nder

veh

icle

s

Con

stru

ctio

n,

En

viro

nmen

tal

coor

dina

tor

2.

Con

stru

ctio

n of

su

rface

in

frast

ruct

ure

Gro

und-

wat

er

Pre

vent

/con

tain

po

ssib

le

hydr

ocar

bon

spilla

ges

A

dher

e to

traf

fic ru

les

M

aint

ain

vehi

cles

on

a re

gula

r bas

is

M

ake

use

of o

il pa

ns

in/u

nder

veh

icle

s

Con

tinuo

usly

Im

plem

ent t

raffi

c ru

les

and

train

dr

iver

s to

und

erst

and

the

rule

s

Im

plem

ent v

ehic

le m

aint

enan

ce

sche

dule

In

stal

l oil

colle

ctio

n pa

ns

in/u

nder

veh

icle

s

Con

stru

ctio

n,

Envi

ronm

enta

l co

ordi

nato

r

M

inin

g co

ntra

ctor

3.

Blas

ting

and

deve

lopm

ent o

f in

itial

box

cut

fo

r min

ing

Gro

und-

wat

er

Pre

vent

/con

tain

co

ntam

inat

ion

from

bla

stin

g m

ater

ial

H

andl

e an

d st

ore

blas

ting

mat

eria

l acc

ordi

ng to

m

anuf

actu

ring

requ

irem

ents

Con

tinuo

usly

Tr

ain

staf

f and

impl

emen

t co

rrec

t pro

cedu

res

for t

he

hand

ling

of b

last

ing

mat

eria

l

O

nly

qual

ified

sta

ff sh

ould

ha

ndle

thes

e m

ater

ials

Con

stru

ctio

n an

d

Envi

ronm

enta

l co

ordi

nato

r

M

inin

g co

ntra

ctor

4.

Tem

pora

ry

stor

age

of

haza

rdou

s pr

oduc

ts w

aste

or

sew

age

Gro

und-

wat

er

Pre

vent

/con

tain

sp

illage

s of

ha

zard

ous

mat

eria

l

S

tore

haz

ardo

us m

ater

ial

acco

rdin

g to

m

anuf

actu

ring

spec

ifica

tions

S

tore

haz

ardo

us m

ater

ial

on c

emen

ted/

conc

rete

flo

or in

a b

unde

d ar

ea

Con

tinuo

usly

Ta

ke m

anuf

actu

rer

reco

mm

enda

tions

into

acc

ount

w

hen

desi

gnin

g an

d co

nstru

ctin

g ha

zard

ous

mat

eria

l sto

rage

spa

ce.

S

tore

haz

ardo

us m

ater

ial i

n th

e co

rrec

t des

igna

ted

area

s,

spec

ially

des

igne

d an

d co

nstru

cted

for t

hat p

urpo

se

Con

stru

ctio

n

En

viro

nmen

tal

coor

dina

tor

M

inin

g co

ntra

ctor

R

isk

asse

ssor

5.

Rem

oval

of

over

burd

en a

nd

back

fillin

g of

th

e pi

t whe

re

poss

ible

Gro

und-

wat

er

Pre

vent

/con

tain

po

ssib

le

hydr

ocar

bon

spilla

ges

A

dher

e to

traf

fic ru

les

M

aint

ain

vehi

cles

on

a re

gula

r bas

is

M

ake

use

of o

il pa

ns

in/u

nder

veh

icle

s

Con

tinuo

usly

Im

plem

ent t

raffi

c ru

les

and

train

dr

iver

s to

und

erst

and

the

rule

s

Im

plem

ent v

ehic

le m

aint

enan

ce

sche

dule

In

stal

l oil

colle

ctio

n pa

ns

in/u

nder

veh

icle

s

Con

stru

ctio

n

Env

ironm

enta

l co

ordi

nato

r

Min

ing

cont

ract

or

Hyd

roge

olog

ical

Ass

essm

ent f

or th

e B

rakf

onte

in E

IA

UN

I 129

2

89

6.

Use

and

M

aint

enan

ce o

f ha

ul ro

ads

(Incl

udin

g tra

nspo

rtatio

n of

coa

l to

was

h pl

ant)

Gro

und-

wat

er

Pre

vent

/con

tain

po

ssib

le

hydr

ocar

bon

spilla

ges

A

dher

e to

traf

fic ru

les

M

aint

ain

vehi

cles

on

a re

gula

r bas

is

M

ake

use

of o

il pa

ns

in/u

nder

veh

icle

s

Con

tinuo

usly

Im

plem

ent t

raffi

c ru

les

and

train

dr

iver

s to

und

erst

and

the

rule

s

Im

plem

ent v

ehic

le m

aint

enan

ce

sche

dule

In

stal

l oil

colle

ctio

n pa

ns

in/u

nder

veh

icle

s

Ope

ratio

nal

En

viro

nmen

tal

coor

dina

tor

Min

ing

cont

ract

or

7.

Min

ing

proc

ess

rem

oval

of c

oal

(ben

ch m

inin

g)

and

RO

M c

oal

stoc

kpile

Gro

und-

wat

er

Pre

vent

/con

tain

gr

ound

wat

er

pollu

tion

as fa

r as

prac

tical

pos

sibl

e

D

iver

t sur

face

flow

s aw

ay

from

the

open

pit

and

stoc

kpile

are

as th

roug

h ch

anne

ls, d

rain

s, c

ulve

rts

and

dyke

s

In

-pit

drai

nage

& s

umps

(th

ese

shou

ld b

e au

tom

ated

whe

re

poss

ible

to p

reve

nt

issu

es w

hen

pers

onne

l ca

nnot

acc

ess

the

site

du

e to

saf

ety

or o

ther

re

ason

s)

In

terc

eptio

n dr

aina

ge

arou

nd th

e pi

t an

d st

ockp

ile a

reas

(Key

to

mak

ing

this

wor

k is

to

min

imiz

e th

e su

rface

ar

ea w

here

ope

ratio

ns

wou

ld c

onta

min

ate

wat

er

smal

ler d

istu

rbed

are

as

mea

n sm

alle

r vol

umes

to

man

age)

From

op

erat

iona

l ph

ase

onw

ards

on

a co

ntin

uous

ba

sis

Con

stru

ct a

nd m

aint

ain

wat

er

man

agem

ent i

nfra

stru

ctur

e

M

onito

r and

com

pare

m

onito

red

data

to b

asel

ine

data

to

det

erm

ine

the

effe

ctiv

enes

s of

miti

gatio

n

Ope

ratio

nal

En

viro

nmen

tal

coor

dina

tor

Min

ing

cont

ract

or

Hyd

roge

olog

ical

Ass

essm

ent f

or th

e B

rakf

onte

in E

IA

UN

I 129

2

90

8.

Wat

er u

se a

nd

stor

age

on s

ite

Gro

und-

wat

er

Man

age

seep

age

from

the

PCD

S

eepa

ge m

ay b

e co

ntro

lled

to s

ome

exte

nt b

y:

im

perm

eabl

e so

ils o

r ge

ofab

ric li

ners

to

cont

ain

seep

age

flow

; an

d

Mon

itorin

g of

see

page

flow

sh

ould

occ

ur a

nd is

nor

mal

ly

acco

mpl

ishe

d by

:

In

stal

ling

piez

omet

ers

to

dete

rmin

e th

e gr

ound

wat

er le

vel

chan

ges

dow

nstre

am;

and

Dur

ing

cons

truct

ion

and

mon

itorin

g on

a

mon

thly

ba

sis

Con

stru

ct P

CD

with

a li

ner

In

stal

l mon

itorin

g bo

reho

les

dow

nstre

am o

f the

PC

D

Im

plem

ent m

onito

ring

and

sam

plin

g pr

oced

ures

Ope

ratio

nal

Hyd

roge

olog

ical

Ass

essm

ent f

or th

e B

rakf

onte

in E

IA

UN

I 129

2

91

9.

Sto

rage

and

ha

ndlin

g of

ha

zard

ous

prod

ucts

was

te

or s

ewag

e

Gro

und-

wat

er

Pre

vent

/con

tain

sp

illage

s of

ha

zard

ous

mat

eria

l

Bu

ndin

g b

est p

ract

ice

thou

ght w

ould

be

to p

ut

up s

ome

roof

ing

and

dire

ct th

e w

ater

out

of t

he

bund

ed a

rea,

Bun

d w

alls

ne

ed to

be

impe

rvio

us to

le

akag

e of

hyd

roca

rbon

s!

Bun

ded

area

s m

ust h

ave

a m

echa

nism

whe

reby

th

e co

ntam

inan

t or

addi

tiona

l rai

n w

ater

is

tapp

ed o

ff an

d m

anag

ed

corr

ectly

;

R

egul

ar in

spec

tions

of

the

stor

age

tank

s an

d pi

ping

for c

orro

sion

and

le

aks;

R

emem

ber t

o m

ake

sure

th

e bu

nd v

alve

s ar

e cl

osed

and

that

the

bund

ed a

rea

is

mai

ntai

ned

dry;

D

iver

ting

oil

cont

amin

ated

wat

er fr

om

the

bund

ed a

rea

durin

g ra

in e

vent

s to

an

inte

rcep

tion

or o

il w

ater

se

para

tion

faci

lity.

Con

tinuo

usly

Ta

ke m

anuf

actu

rer

reco

mm

enda

tions

into

acc

ount

w

hen

desi

gnin

g an

d co

nstru

ctin

g ha

zard

ous

mat

eria

l sto

rage

spa

ce.

S

tore

haz

ardo

us m

ater

ial i

n th

e co

rrec

t des

igna

ted

area

s,

spec

ially

des

igne

d an

d co

nstru

cted

for t

hat p

urpo

se

Tr

ain

staf

f and

impl

emen

t co

rrec

t pro

cedu

res

for t

he

hand

ling

of h

azar

dous

mat

eria

l

D

o re

gula

r ins

pect

ions

of

stor

age

area

s

In

stal

l and

mai

ntai

n an

d oi

l tra

p at

fuel

sto

rage

are

as

Ope

ratio

nal

Hyd

roge

olog

ical

Ass

essm

ent f

or th

e B

rakf

onte

in E

IA

UN

I 129

2

92

10. C

oncu

rren

t re

plac

emen

t of

over

burd

en,

tops

oil a

nd re

-ve

geta

tion

Gro

und-

wat

er

Pre

vent

/ con

tain

po

llutio

n as

far a

s pr

actic

al p

ossi

ble

Pol

lutio

n co

ntro

l mea

sure

s co

uld

incl

ude:

In

terc

eptio

n dr

aina

ge

arou

nd th

e pi

t (K

ey to

m

akin

g th

is w

ork

is to

m

inim

ize

the

surfa

ce

area

whe

re o

pera

tions

w

ould

con

tam

inat

e w

ater

sm

alle

r dis

turb

ed a

reas

m

ean

smal

ler v

olum

es to

m

anag

e;

In

term

s of

gro

undw

ater

th

e in

filtra

tion

to

grou

ndw

ater

sho

uld

be

cont

rolle

d an

d ca

n be

ac

hiev

ed th

roug

h in

stal

latio

n of

line

rs,

suffi

cien

t sur

face

dr

aina

ge a

nd s

urfa

ce

capp

ing

to in

sula

te

agai

nst i

nfilt

ratio

n.

At

tenu

atio

n of

gr

ound

wat

er

cont

amin

atio

n m

ay b

e ac

hiev

ed b

y in

stal

ling

slur

ry w

alls

, gro

ut

curta

ins

or s

heet

pilin

g.

Thes

e m

etho

ds s

houl

d on

ly b

e em

ploy

ed a

fter

sour

ce c

ontro

l met

hods

ha

ve fa

iled

Dur

ing

cons

truct

ion

and

cont

inuo

usly

du

ring

Ope

ratio

nal

phas

e

Impl

emen

t and

mai

ntai

n pr

oper

st

orm

wat

er m

anag

emen

t in

frast

ruct

ure

Im

plem

ent r

ehab

ilitat

ion

plan

un

der s

uper

visi

on o

f sui

tabl

y qu

alifi

ed p

erso

n

Ope

ratio

nal,

Dec

omm

issi

onin

g

11. D

emol

ition

and

re

mov

al o

f all

infra

stru

ctur

e

Gro

und-

wat

er

Pre

vent

/con

tain

po

ssib

le

hydr

ocar

bon

spilla

ges

A

dher

e to

traf

fic ru

les

M

aint

ain

vehi

cles

on

a re

gula

r bas

is

M

ake

use

of o

il pa

ns

in/u

nder

veh

icle

s

Con

tinuo

usly

Im

plem

ent t

raffi

c ru

les

and

train

dr

iver

s to

und

erst

and

the

rule

s

Im

plem

ent v

ehic

le m

aint

enan

ce

sche

dule

In

stal

l oil

colle

ctio

n pa

ns

in/u

nder

veh

icle

s

Dec

omm

issi

onin

g

Hyd

roge

olog

ical

Ass

essm

ent f

or th

e B

rakf

onte

in E

IA

UN

I 129

2

93

12. R

ehab

ilitat

ion

G

roun

d-w

ater

M

inim

ise

infil

tratio

n of

le

acha

te fr

om

min

e w

aste

fa

cilit

ies

and

min

ed a

reas

C

onta

min

ated

runo

ff or

le

acha

te d

eriv

ed fr

om

was

te d

umps

can

be

inte

rcep

ted

by d

rain

s an

d ve

geta

tion

filte

rs b

etw

een

the

disc

ard

dum

p an

d th

e dr

ains

and

dire

cted

to

stor

age

pond

s.

th

e in

filtra

tion

to

grou

ndw

ater

sho

uld

be

cont

rolle

d an

d ca

n be

ac

hiev

ed th

roug

h in

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UNI 1292

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8 MONITORING PROGRAMME

8.1 Monitoring Boreholes

The main objective in positioning monitoring boreholes is to intersect groundwater prior to and moving away from a pollution source and to intercept water levels at select intervals away from a well field used for water supply.

Depending on the final mine plan it is recommended that monitoring boreholes be selected by a qualified hydrogeologist in order to intercept preferential flow paths and select monitoring boreholes within the expected perimeter of the modelled impact zones.

8.2 Groundwater Levels

Groundwater levels must be recorded on a monthly basis to within accuracy of 0.1 m, using an electrical contact tape, float mechanism or pressure transducer to detect any changes or trends in groundwater levels.

8.3 Water Sampling and Preservation

The following procedures are proposed for sampling:

1 l plastic bottles, with a plastic cap and no liner within the cap are required for most sampling exercises. Glass bottles are required if organic constituents are to be tested for. Sample bottles should be marked clearly with the borehole name, date of

Water levels should be measured prior to taking the sample, using a dip meter (m mbgl);

Each borehole to be sampled should be purged (to ensure sampling of the aquifer and not stagnant water in the casing) using a submersible pump or in the event of an obstruction in a borehole, a clean disposable polyethylene bailer. At least three borehole volumes of water should be removed through purging; or through continuous water quality monitoring, until the electrical conductivity value stabilizes;

Metal samples must be filtered in the field to remove clay suspensions;

Samples should be kept cool in a cooler box in the field and kept cool prior to being submitted to the laboratory; and

The pH and EC meter used for field measurements should be calibrated daily using standard solutions obtained from the instrument supplier.

8.3.1 Sample Frequency

A quarterly sampling frequency is recommended for groundwater quality.


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8.3.2 Sample Analysis

Water samples must be analysed by an accredited analytical laboratory that uses approved analytical procedures. The following process is recommended for constituent analyses:

8.3.2.1 Comprehensive Analysis

For all new sites and first time monitoring at existing sites, a comprehensive analysis is required. It is essential that accurate background levels, for as wide a range of constituents as possible, be established at the outset. This will usually include a complete macro analysis as well as an analysis for the trace elements that could reasonably be expected to be present within the environment tested.

8.3.2.2 Indicator analysis

Indicator analysis may be performed once comprehensive analyses have been completed. The process may continue until undesirable trends are uncovered. This will keep analytical costs to a minimum, but still provide enough information upon which further actions can be initiated, if necessary. Depending on the type of waste handled, so-

This should be reviewed on an annual basis to assess whether it is needed to monitor for additional variables.

Monitoring results will be captured in an electronic database as soon as results become available allowing:

Data presentation in tabular format;

Time-series graphs for comparison;

Statistical analysis (minimum, maximum, average) in tabular/whisker box plot format;

Linear trend determination;

Performance analysis in tabular format;

Presentation of data, statistics and performance on diagrams and maps; and

Comparison and compliance to legal or best practice water quality standards.

8.4 Reporting

The contents of the report should include the quarterly results at groundwater monitoring positions as well as comments on the effectiveness of the mitigation measures and monitoring program.

Reporting to the authorities, if required should be as specified in the permitting/licensing conditions.

Any accidental release of pollutants or potential polluting substances should be reported to the relevant authorities as specified in the permitting/licensing conditions.


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8.5 Responsibilities

Responsibility for water management should lie with an environmental party which will ensure that all water management actions are undertaken and implemented. The environmental party will ensure that the monitoring, management and reporting of water management conclusions are according to the water management plan.

Responsibility for analysis of water samples will lie with an appointed laboratory.

9 CONCLUSION

9.1 Groundwater Baseline Information

A field work assessment comprising of site visits for hydro-census, geophysics, drilling, aquifer testing and geochemical sampling programmes where conducted since May 2012 until July 2012 to establish the background (baseline) groundwater condition of the proposed Brakfontein Project site. Universal Coal plans to develop five opencast pits and an underground mine section to extract coal for local and international demand.

Seventeen borehole locations where identified during the hydro-census. The hydro-census identified the project area as agricultural and pastoral farming communities with historical and current coal mining occurring on neighbouring farms to the project area. Operating boreholes are utilised for domestic, stock watering and irrigation purposes.

To supplement the results of the desktop study and hydro-census geophysics was utilised to establish five additional boreholes within the Brakfontein Project site. These additional boreholes assisted with defining hydrogeological and geological parameters for the project area conceptual and numerical model.

Four aquifers have been identified for the project area, a minor shallow weathered aquifer, a minor fractured Karoo aquifer, a Dwyka non-aquifer and a major pre-Karoo dolomitic aquifer. Aquifer tests confirmed the classification of the aquifers (as minor or major) with boreholes intersecting the Karoo Supergroup lithologies achieving water strikes with weak yields ranging from dry to transmissivity of 1.7m2/d whilst the pre-Karoo dolomitic aquifer borehole achieved a yield of 36 1.7m2/d. The testing of the pre-Karoo borehole was limited by the 127mm inner diameter size of the borehole casing which restricted the pump size.

Water levels observed at the Brakfontein site varies between 1535 mamsl (BRABH02) and 1586 mamsl (UNI04).However, localised variations may occur as a result of mining activities and groundwater abstraction for agricultural irrigation purposes in some areas.

The Flow direction of the groundwater in the study area correlates fairly well with the surface topography. The Bayesian correlations for pre mining conditions are shown in Figure 4. The water levels observed at the mining area shows a correlation of


UNI 1292

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79.13% leading to the conclusion that the groundwater flow direction generally mimics the surface topography.

Based on the underlying hydrogeology of the project area, and the corresponding aquifer test results and analyses, the aquifers have been classified according to

Weathered Aquifer Minor Aquifer

Fractured Karoo Aquifer Minor Aquifer

Dwyka Tillite Aquifer Non Aquifer

Basement Karst Aquifer Major Aquifer

Groundwater quality varies with majority of the samples and sample constituents indicating acceptable concentrations compared against the South African National Standard (SANS) 241: 2005 guidelines for drinking water. Samples not complying to acceptable standards are described as follows:


UNI07 contains excessive (above Class II maximum allowable) concentrations of fluoride (1.56 mg/l). Presence of fluoride can be found naturally in groundwater or present from anthropogenic contamination. This is the only borehole located on the left of both the faults, which can suggest that the source of fluoride is localised to this area by the fault. Whether the source of fluoride is natural or anthropogenic is undermined;


BRABH 05 contains elevated to Class II (maximum allowable) concentrations of manganese (0.21 mg/l). The background manganese concentrations are very low for the area as determined by the other groundwater samples indicating an additional source of manganese is present for this borehole. The source can be natural (intersections with coal layers) or as contamination from historical mine workings.

In general the groundwater has a slightly acidic to slightly alkaline pH range (5.5 to 8.6), with low salinity concentrations (below 550mg/l). Water type for the project area as defined by the Piper diagram indicates a sodium-potassium bicarbonate to calcium-magnesium bicarbonate with a range in sulphate from 5% to 55%. BRABH 01 and BRABH 03 indicate a calcium-magnesium chloride water type. Variability of sulphate and water type is dependent on individual boreholes and no regional distribution trend could be identified.


UNI 1292

99

The acid-base accounting geochemical results indicates all samples are potentially acid generating with negative net neutralising potentials. The average neutralising potential is 0.67 kg/t (CaCO3) and average acid potential is 23.37 kg/t (CaCO3) resulting in an average net neutralising potential of -22.70 kg/t (CaCO3). In general the upper seams (seam 1 and seam 2) indicate the worst results with the lower seam 4 and interburden samples indicating better net neutralising potential results.

9.2 Groundwater Numerical Modelling

The potential impact of the proposed mining activities on the groundwater environment has to be qualified, using the baseline geohydrological information and calibrated numerical flow and transport model. The numerical model has been used to simulate the impacts of the open cast areas, undegroundwater receptors. The scenarios modelled include:



The predicted inflow rates for the opencast pits and underground mining over the LoM are shown in the table below. Total predicted inflow rates at the proposed Brakfontein mine will range from a minimum of 6.39 l/s calculated for Year 12 to a maximum of 23.16 l/.s calculated for Year 6.


1 1 272 1 272 14.72

2 709 420 1 129 13.07

3 860 428 1 288 14.91

4 639 1 164 1 803 20.87

5 663 1 172 1 835 21.23

6 637 1364 2 001 23.16

7 522 1285 1 807 20.91

8 542 798 1 340 15.51

9 1741.5 1 742 20.16

10 749 749 8.67


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100


11 765.5 766 8.86

12 552 552 6.39

13 556.5 557 6.44

14 589 589 6.82

15 825 825 9.55

16 618 618 7.15

17 854.5 855 9.89

18 921.5 922 10.67

19 938.5 939 10.86

20 1245 1 245 14.41

The model qualified and delineated the groundwater drawdown cone (zone in which the groundwater level is lowered as a result of abstraction) during mine dewatering over time. During the operational phase the cone of depression extends approximately 1100m to the south, 300 m to the west and 500m to the north and east of OC 3, 4 and 5, and approximately 400 500m in all directions from OC 1 and 2 (Figure 20).

Seepage from the discard dumps is likely to have elevated salt load consisting predominantly of high TDS, SO4 and Ca concentrations. The results from the acid base accounting tests suggest that the waste rock material is likely to have a net potential to generate acid mine drainage. Groundwater numerical modelling predict that seepage water quality diluted to 5% of the input concentration of 100% is likely to migrate up to between 150m and 300m

9.3 Impact Assessment

The most significant impacts will occur during the operational and decommissioning phase of mining. These are listed below and the impact ratings are given in section 5.

Removal of overburden and backfilling: Rainwater infiltrating through the overburden stockpiles and/or backfilled material and the underlying soils into the groundwater environment could pollute the aquifers, by means of an increased salt load and metals. Acid base accounting tests completed during this investigation indicate a net acid potential in all samples analysed.


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Removal of coal (mining process) and ROM coal Stockpile: The removal of coal will lead to a decrease in water level as water flows into the opencast pit. The impact of the proposed mine on regional groundwater resources and users have been qualified using the numerical groundwater model. The model qualified and delineated the groundwater drawdown cone (zone in which the groundwater level is lowered as a result of abstraction) during mine dewatering over time. During the operational phase the cone of depression extends approximately 1100m to the south, 300 m to the west and 500m to the north and east of OC 3, 4 and 5, and approximately 400 500m in all directions from OC 1 and 2 (Figure 20).

Storage, handling and treatment of hazardous products (fuel, explosives, oil) and waste activities (Mine waste discard, sewage): The storage of hazardous products and mine waste material such as sewage may have a potential negative effect on ground-water quality should there be a spillage/leaks that could infiltrate through the soils to reach the groundwater table. Seepage from the discard dumps is likely to have elevated salt load consisting predominantly of high TDS, SO4 and Ca concentrations. The results from the acid base accounting tests suggest that the waste rock material is likely to have a net potential to generate acid mine drainage. Groundwater numerical modelling predict that seepage water quality diluted to 5% of the input concentration of 100% is likely to migrate up to between 100m and 150m


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10 REFERENCES

Barnard, H.C. (2000). An explanation of the 1:500 000 General Hydrogeological Map,

Johannesburg 2526. Department of Water Affairs and Forestry.

Chiang, W.-H. and Kinzelbach, W. 2000. 3D-Groundwater Modeling with PMWIN A

Simulation System for Modeling Groundwater Flow and Pollution. Springer-Verlag Berlin Heidelberg New York, S.346.

Department of Water Affairs and Forestry (1996). South African Water Quality Guidelines

(second edition). Volume 1: Domestic Use.

Duncan, A.R. and Marsh, J.S. (2006). The Karoo Igneous Province. In: Johnson, M.R., Anhaeusser, C.R. and Thomas, R.J. (Eds.), The Geology of South Africa. Geological Society of South Africa, Johannesburg/Council for Geoscience, Pretoria, 501-520.

Hodgson, F.D.I. and Krantz, R.M. (1998). Groundwater quality deterioration in the

Olifants River Catchment above the Loskop Dam with specialised investigation in the

Witbank Dam sub-catchment. Report to the Water Research Commission by the Institute for Groundwater Studies, University of the Free State. WRC Report No 291/1/98.

Johnson, M.R., van Vuuren, C.J., Visser, J.N.J, Cole, D.I., de V. Wickens, H., Christie, A.D.M., Roberts, D.L. and Brandl, G. (2006). Sedimentary Rocks of the Karoo

Supergroup. In: Johnson, M.R., Anhaeusser, C.R. and Thomas, R.J. (Eds.), The Geology of South Africa. Geological Society of South Africa, Johannesburg/Council for Geoscience, Pretoria, 461-500.

Kruseman G P, De Ridder N A (1994) Analysis and Evaluation of Pumping Test Data. International Institute for Land Reclamation and Improvement (IRLI).

Parsons, R. and Conrad. J. (1998). Explanatory notes for the Aquifer Classification Map

of South Africa. Report to the Water Research Commission by the Division of Water Environment and Forestry Technology, CSIR. WRC Report No KV 116/98.

Schwartz F W, Zhang H (2003) Fundamentals of Groundwater. John Wiley & Sons Inc.


UNI 1292

Appendix A: [Geophysical survey]

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UNI 1292

Appendix B: [Borehole logs]

��

��

��

�

��

��

PROJECT: UNI 1292 BOREHOLE ID: BRABH 01

CLIENT: UNIVERSAL COAL GOEPHYSICS TARGETS ID: TARGET 03

LOCATION: BRAKFONTEIN X-COORDINATE: 28.8745

DRILLING SUBCONTRACTOR: GEOSPHERE Y-COORDINATE: -26.20741

LOGGED BY: MEGAN Z-COORDINATE (MAMSL): 1549

NEARBY OTHER BH: BRABH 02 and BRABH 03 FINAL DEPTH: 60 m

NEARBY RIVER/STREAM: WILGE RIVER FINAL BLOW OUT YIELD: DRY

DRILLING METHODE: PERCUSSION DATE COMPLETED: 11/06/2012

COORDINATE SYSTEM: DECIMAL DEGREES, WGS 84 DATE WATER LEVEL MEASURED: 15/06/2012

Stand Pipe =

Cement Block -

Red iron rich Overburden

Solid steel casing: Light brown

165mm internal diameter

5 Solid uPVC casing: 5 Weathered, light brown, incompetent with minor calcite Karoo Supergroup 5

127mm internal diameter 6.4 becomes finer grained with depth

Perforated uPVC casing:

10 127mm internal diameter 10 Finer grained 10

Fresh, dull

15 15 Bright 15

Dark grey, incompetent

20 20 20

25 25 25

Bright

30 30 30

Light grey with minor coal

Light grey brown, incompetent

35 35 35

40 40 40

45 45 45

Shale becomes competent

Light blue competent

50 50 50

55 55 55

60 60 60

COAL

SHALE

Bo

reh

ole

inte

rsec

ted

no

wat

er s

trik

es

SANDSTONE

WATER STRIKES (l/hr)

GEOLOGICAL DESCRIPTIONDEPTH m

SILTSTONE

COAL

DEPTH mHOLE

DIAMETER CONSTRUCTION

STATIC WATER LEVEL (m bgl)

CARBONACEOUS SHALE and COAL

SOIL

DEPTH m

Penetration Rates Time Per

rod minGeology Description Lithostratigraphy

CARBONACEOUS SHALE

PERCUSSION BOREHOLE LOG

Environmental Solutions Provider







NEARBY RIVER/STREAM: WILGE RIVER FINAL BLOW OUT YIELD: WEAK, NOT ENOUGH WATER FOR A BLOW YIELD



Stand Pipe =

Cement Block -

Red brown, coarse grained OVERBURDEN

Solid steel casing: Light brown, seepage

5 165mm internal diameter 5 5

5.5

Perforated uPVC casing: Peat like texture to bright incompetent coal, fresh KAROO SUPERGROUP


10 10 10

Solid uPVC casing:


Grey, incompetent, becomes finer with depth

15 15 15

20 20 20

25 25 25

30 30 30

35 35 35

Weathered material indicates possible fracture

40 40 Minor coal present 40

Bright, incompetent

45 45 45

Dark brown grey, fine grained, incompetent

Becomes more competent with depth as well as lighter grey

50 50 50

55 55 55

60 60 60

No

Sig

nif

ican

t W

ater

Str

ike

SOIL and CLAY

CLAY

CLAY and COAL

COAL


GEOLOGICAL DESCRIPTIONDEPTH mDEPTH mHOLE



SOIL and GRAVEL

SANDSTONE and SILTSTONE

DEPTH m



SHALE


COAL

SHALE and SILTSTONE








NEARBY RIVER/STREAM: WILGE RIVER FINAL BLOW OUT YIELD: 6 l/s



Stand Pipe =

Cement Block -

Red brown, Iron rich with ferricrete nodules OVERBURDEN

Solid steel casing:


5.6 Light brown, iron deplete with calcrete



Fresh, dark blue, fractured with iron oxidation, chert rich (silicious TRANSVAAL

10 10 texture throughout) SUPERGROUP 10

Solid uPVC casing:


15 15 Strong oxidation with water strike 15

Dark grey, strongly weathered with brown clay (fracture)

20 20 20

25 25 25

Dark grey, oxidised on fractures (?)

30 30 30

35 35 35

40 40 40

45 45 45

50 50 50

55 55 55

60 6.0 60 60




DOLOMITE

DEPTH mHOLE



SOIL

DEPTH m








LOGGED BY: DANIEL Z-COORDINATE (MAMSL): 1563

NEARBY OTHER BH: BRABH 05 FINAL DEPTH: 60 m

NEARBY RIVER/STREAM: WILGE RIVER FINAL BLOW OUT YIELD: WEAK, NOT ENOUGH WATER FOR A BLOW YIELD


COORDINATE SYSTEM: DECIMAL DEGREES, WGS 84 DATE WATER LEVEL MEASURED:

Stand Pipe =

Cement Block -

Red brown, coarse grained OVERBURDEN

Light brown, seepage

5 5 5

Solid steel casing: Light grey, fine grained, seepage KAROO SUPERGROUP


10 10 10

Perforated uPVC casing: Light brown to yellowish, fine to coarse grains, fresh


15 15 15

Solid uPVC casing:


20 20 Interlaminated sequence of shale and sandstone 20

Dark grey, fine grains

25 25 25

Dark grey to black, fine grained

30 30 30

35 35 35

Quartz vein intrusion

Dark grey to black, fine grained

40 40 40

45 45 45

50 50 50

55 55 Grey, very fine grained, fresh 55

60 60 60

DOLERITE

QUARTZ


No

Sig

nif

ican

t W

ater

Str

ike

SANDSTONE and SILTSTONE

DWYKA TILLITE

DEPTH m



DEPTH mHOLE



SOIL



SILTSTONE

DOLERITE

CLAY

SHALE and SANDSTONE

SHALE






LOGGED BY: DANIEL Z-COORDINATE (MAMSL): 1577

NEARBY OTHER BH: BRABH 04 FINAL DEPTH: 60 m

NEARBY RIVER/STREAM: WILGE RIVER FINAL BLOW OUT YIELD: 1.8 l/s



Stand Pipe =

Cement Block

Red brown, top soil ,coarse grained OVERBURDEN

Light brown to yellow, coarse grain, weathered, mica KAROO SUPERGROUP

Solid steel casing: Light brown, seepage


Light yellow, fine grained, seepage

Solid uPVC casing:


10 10 10

15 15 15



25 25 25

Light orange, coarse grained

Grey to black, interlaminated sequence of coal and sandstone

Black

30 30 30

35 35 35

1.8l/s

Light grey, coarse grained

40 40 40

Grey to black, interlaminated sequence of coal and sandstone

45 45 45

Black

50 50 50

Grey, fresh

55 55 55

60 60 60

COAL

SANDSTONE

SANDSTONE and COAL


DOLERITE

DEPTH m



DEPTH mHOLE



SOIL



SANDSTONE and COAL

SILTSTONE

SANDSTONE

SANDSTONE

COAL



UNI 1292

Appendix C: [Laboratory results certificates]

T0374

29 May 2012

Test ReportClient:

Address:

Report No:

Date of certificate:

Date accepted:

Date completed:

Page: 1 of 2

Digby Wells & Associates 29 May 2012

22 May 2012359 Pretoria Ave, Fern Isle, Section 5, Ferndale, Randburg

8291 Project: Digby Wells & Associates

Lab no:

Date sampled:

Sample type:

Locality description

Analyses: Method

A = Accredited (Included in the SANAS Schedule of Accreditation); N = Not accredited (Excluded from the SANAS Schedule of Accreditation)OSD = Outsourced; S = Sub-contracted; NR = Not requested; RTF = Results to follow; TNTC = To numerous to count; ND = Not detectedNATD = Not able to determine

Clean Stream Scientific Services does not accept responsibility for any matters arising from the further use of these results. This certificate shallnot be reproduced without written approval by the Managing Director. Measurement of uncertainty available on request for all methods includedin the SANAS Schedule of Accreditation. This report only relates to the above samples and variables analysed.

Report checked by: H. Holtzhausen (Laboratory Manager)

89257

17 May 2012

Water

WILGE 01

89258

18 May 2012

Water

WILGE 02

89259

16 May 2012

Water

UNI 02

89260

17 May 2012

Water

UNI 07

89261

17 May 2012

Water

UNI 09

89262

17 May 2012

Water

UNI 011

89263

17 May 2012

Water

UNI 012

A pH CSM 20 8.20 7.67 7.61 8.18 7.93 8.17 8.31A Electrical conductivity (EC) mS/m CSM 20 62.20 41.60 20.20 48.70 53.60 50.30 60.20A Total dissolved solids (TDS) mg/l CSM 06 531 276 176 298 278 545 465A Total alkalinity mg/l CSM 01 257.7 173.5 95.5 202.9 159.0 140.0 204.5A Chloride (Cl) mg/l CSM 02 26.4 20.5 19.1 39.8 21.5 56.3 35.0A Sulphate (SO4) mg/l CSM 03 186.79 61.02 36.36 19.24 64.49 221.96 140.55A Nitrate (NO3) mg/l as N CSM 06 <0.057 <0.057 1.465 <0.057 7.826 1.483 1.112A Ammonium(NH4) mg/l as N CSM 05 0.550 0.117 0.167 0.326 0.342 0.208 0.320A Orthophosphate (PO4) mg/l as P CSM 04 0.028 <0.025 0.037 <0.025 0.080 0.081 0.128A Fluoride (F) mg/l CSM 11 0.361 0.338 <0.183 1.558 <0.183 <0.183 0.461A Calcium (Ca) mg/l CSM 30 54.503 31.711 19.508 9.767 40.752 25.053 18.134A Magnesium (Mg) mg/l CSM 30 42.972 23.359 10.382 6.394 28.886 14.527 15.239A Sodium (Na) mg/l CSM 30 61.89 32.08 28.52 99.98 14.26 138.64 130.44A Potassium (K) mg/l CSM 30 3.499 3.636 3.565 1.122 4.996 2.869 2.033A Aluminium (Al) mg/l CSM 31 0.138 <0.006 0.211 <0.006 0.022 0.038 0.030A Iron (Fe) mg/l CSM 31 0.053 <0.006 <0.006 <0.006 <0.006 <0.006 <0.006A Manganese (Mn) mg/l CSM 31 0.107 <0.001 <0.001 <0.001 <0.001 <0.001 0.005A Total chromium (Cr) mg/l CSM 31 <0.002 <0.002 <0.002 <0.002 <0.002 <0.002 <0.002A Copper (Cu) mg/l CSM 31 <0.001 <0.001 <0.001 <0.001 0.002 <0.001 0.020A Nickel (Ni) mg/l CSM 31 <0.003 <0.003 <0.003 <0.003 <0.003 <0.003 0.011A Zinc (Zn) mg/l CSM 31 <0.004 <0.004 0.039 0.015 <0.004 <0.004 <0.004A Cobalt (Co) mg/l CSM 31 <0.002 <0.002 <0.002 <0.002 <0.002 <0.002 <0.002A Cadmium (Cd) mg/l CSM 31 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001A Lead (Pb) mg/l CSM 31 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001A Total hardness mg/l CSM 26 313 175 91 51 221 122 108

T0374

29 May 2012

Test ReportClient:

Address:

Report No:


Date accepted:

Date completed:

Page: 2 of 2

Digby Wells & Associates 29 May 2012

22 May 2012359 Pretoria Ave, Fern Isle, Section 5, Ferndale, Randburg


Lab no:

Date sampled:

Sample type:


Analyses: Method




89264

17 May 2012

Water

UNI 014

89265

18 May 2012

Water

UNI 015

89266

18 May 2012

Water

UNI 016

A pH CSM 20 7.59 7.17 7.92A Electrical conductivity (EC) mS/m CSM 20 69.10 16.37 44.00A Total dissolved solids (TDS) mg/l CSM 06 444 93 283A Total alkalinity mg/l CSM 01 281.1 66.6 217.3A Chloride (Cl) mg/l CSM 02 29.0 8.7 18.6A Sulphate (SO4) mg/l CSM 03 80.20 4.76 32.99A Nitrate (NO3) mg/l as N CSM 06 1.633 3.933 1.032A Ammonium(NH4) mg/l as N CSM 05 0.163 0.090 0.178A Orthophosphate (PO4) mg/l as P CSM 04 0.088 0.278 0.084A Fluoride (F) mg/l CSM 11 0.369 0.192 0.218A Calcium (Ca) mg/l CSM 30 40.716 12.818 41.953A Magnesium (Mg) mg/l CSM 30 22.387 7.367 18.438A Sodium (Na) mg/l CSM 30 100.18 12.58 35.32A Potassium (K) mg/l CSM 30 1.139 2.593 4.042A Aluminium (Al) mg/l CSM 31 <0.006 0.029 <0.006A Iron (Fe) mg/l CSM 31 <0.006 <0.006 <0.006A Manganese (Mn) mg/l CSM 31 <0.001 <0.001 0.005A Total chromium (Cr) mg/l CSM 31 <0.002 <0.002 <0.002A Copper (Cu) mg/l CSM 31 <0.001 <0.001 <0.001A Nickel (Ni) mg/l CSM 31 <0.003 <0.003 <0.003A Zinc (Zn) mg/l CSM 31 0.066 0.962 0.039A Cobalt (Co) mg/l CSM 31 <0.002 0.002 <0.002A Cadmium (Cd) mg/l CSM 31 <0.001 <0.001 <0.001A Lead (Pb) mg/l CSM 31 <0.001 <0.001 <0.001A Total hardness mg/l CSM 26 194 62 181

T0374

12 Jun 2012

Test ReportClient:

Address:

Report No:


Date accepted:

Date completed:

Page: 1 of 1

Digby Wells & Associates 12 Jun 2012

07 Jun 2012359 Pretoria Ave, Fern Isle, Section 5, Ferndale, Randburg


Lab no:

Date sampled:

Sample type:


Analyses: Method




90383

06 Jun 2012

Water

UNI 04

A pH CSM 20 7.61A Electrical conductivity (EC) mS/m CSM 20 35.16A Total dissolved solids (TDS) mg/l CSM 26 165A Total alkalinity mg/l CSM 01 108.0A Chloride (Cl) mg/l CSM 02 11.3A Sulphate (SO4) mg/l CSM 03 2.72A Nitrate (NO3) mg/l as N CSM 06 17.482A Ammonium(NH4) mg/l as N CSM 05 <0.015A Orthophosphate (PO4) mg/l as P CSM 04 0.034A Fluoride (F) mg/l CSM 08 <0.183A Calcium (Ca) mg/l CSM 30 35.909A Magnesium (Mg) mg/l CSM 30 17.739A Sodium (Na) mg/l CSM 30 9.55A Potassium (K) mg/l CSM 30 5.773A Aluminium (Al) mg/l CSM 31 <0.006A Iron (Fe) mg/l CSM 31 <0.006A Manganese (Mn) mg/l CSM 31 <0.001A Total chromium (Cr) mg/l CSM 31 <0.002A Copper (Cu) mg/l CSM 31 <0.001A Nickel (Ni) mg/l CSM 31 <0.003A Zinc (Zn) mg/l CSM 31 <0.004A Cobalt (Co) mg/l CSM 31 <0.002A Cadmium (Cd) mg/l CSM 31 <0.001A Lead (Pb) mg/l CSM 31 <0.001A Total hardness mg/l CSM 26 163

T0374

26 Jun 2012

Test ReportClient:

Address:

Report No:


Date accepted:

Date completed:

Page: 1 of 1

Digby Wells & Associates 26 Jun 2012

22 Jun 2012359 Pretoria Ave, Fern Isle, Section 5, Ferndale, Randburg


Lab no:

Date sampled:

Sample type:


Analyses: Method




92133

15 Jun 2012

Water

BRABH 01

92134

15 Jun 2012

Water

BRABH 02

92135

15 Jun 2012

Water

BRABH 04

A pH CSM 20 5.58 6.80 7.77A Electrical conductivity (EC) mS/m CSM 20 15.78 24.39 29.90A Total dissolved solids (TDS) mg/l CSM 26 57 131 154A Total alkalinity mg/l CSM 01 12.1 111.1 134.0A Chloride (Cl) mg/l CSM 02 11.5 6.2 9.0A Sulphate (SO4) mg/l CSM 03 2.62 11.88 2.06A Nitrate (NO3) mg/l as N CSM 06 9.003 0.393 1.371A Ammonium(NH4) mg/l as N CSM 05 <0.015 0.134 0.062A Orthophosphate (PO4) mg/l as P CSM 04 <0.025 <0.025 <0.025A Fluoride (F) mg/l CSM 08 <0.183 0.279 <0.183A Calcium (Ca) mg/l CSM 30 7.031 21.180 20.869A Magnesium (Mg) mg/l CSM 30 5.218 11.002 9.421A Sodium (Na) mg/l CSM 30 9.45 11.07 27.49A Potassium (K) mg/l CSM 30 4.799 2.983 3.513A Aluminium (Al) mg/l CSM 31 0.482 <0.006 <0.006A Iron (Fe) mg/l CSM 31 0.069 <0.006 <0.006A Manganese (Mn) mg/l CSM 31 0.001 0.032 <0.001A Total chromium (Cr) mg/l CSM 31 <0.002 <0.002 <0.002A Copper (Cu) mg/l CSM 31 <0.001 <0.001 <0.001A Nickel (Ni) mg/l CSM 31 <0.003 <0.003 <0.003A Zinc (Zn) mg/l CSM 31 0.031 0.010 <0.004A Cobalt (Co) mg/l CSM 31 <0.002 <0.002 <0.002A Cadmium (Cd) mg/l CSM 31 <0.001 <0.001 <0.001A Lead (Pb) mg/l CSM 31 <0.001 <0.001 <0.001A Total hardness mg/l CSM 26 39 98 91

T0374

06 Jul 2012

Test ReportClient:

Address:

Report No:


Date accepted:

Date completed:

Page: 1 of 1

Digby Wells & Associates 06 Jul 2012

03 Jul 2012359 Pretoria Ave, Fern Isle, Section 5, Ferndale, Randburg


Lab no:

Date sampled:

Sample type:


Analyses: Method

A = Accredited (Included in the SANAS Schedule of Accreditation); N = Not accredited (Excluded from the SANASSchedule of Accreditation); OSD = Outsourced; S = Sub-contracted; NR = Not requested; RTF = Results to follow;TNTC = To numerous to count; ND = Not detected; NATD = Not able to determine

Aquatico Laboratories does not accept responsibility for any matters arising from the further use of these results.Measurement of uncertainty available on request. This report only relates to the above samples and variables analysed.


92648

28 Jun 2012

Water

BR BH 03

92649

01 Jul 2012

Water

BR BH 05

A pH CSM 20 7.47 8.67A Electrical conductivity (EC) mS/m CSM 20 12.77 39.70A Total dissolved solids (TDS) mg/l CSM 26 41 220A Total alkalinity mg/l CSM 01 12.6 216.3A Chloride (Cl) mg/l CSM 02 8.7 6.0A Sulphate (SO4) mg/l CSM 03 0.64 0.64A Nitrate (NO3) mg/l as N CSM 06 6.627 <0.057A Ammonium(NH4) mg/l as N CSM 05 0.037 0.457A Orthophosphate (PO4) mg/l as P CSM 04 <0.025 0.033A Fluoride (F) mg/l CSM 08 <0.183 0.317A Calcium (Ca) mg/l CSM 30 6.835 41.165A Magnesium (Mg) mg/l CSM 30 5.730 11.658A Sodium (Na) mg/l CSM 30 3.41 23.60A Potassium (K) mg/l CSM 30 1.605 6.861A Aluminium (Al) mg/l CSM 31 0.007 <0.006A Iron (Fe) mg/l CSM 31 <0.006 <0.006A Manganese (Mn) mg/l CSM 31 <0.001 0.214A Total chromium (Cr) mg/l CSM 31 <0.002 <0.002A Copper (Cu) mg/l CSM 31 <0.001 <0.001A Nickel (Ni) mg/l CSM 31 <0.003 <0.003A Zinc (Zn) mg/l CSM 31 <0.004 0.016A Cobalt (Co) mg/l CSM 31 0.009 <0.002A Cadmium (Cd) mg/l CSM 31 <0.001 <0.001A Lead (Pb) mg/l CSM 31 <0.001 <0.001A Total hardness mg/l CSM 26 41 151

Telephone: +2712 – 349 – 1066 Facsimile: +2712 – 349 – 2064 Email: [email protected]

WATERLAB (PTY) LTD

CERTIFICATE OF ANALYSES ACID – BASE ACCOUNTING

EPA-600 MODIFIED SOBEK METHOD

Date received: 2012-06-15 Date completed: 2012-07-12 Project number: 1000 Report number: 35600 Order number: UNI1292

Client name: Digby Wells & Associates Contact person: Megan Edwards Address: Private Bag X 10046, Randburg, 2125 Email: [email protected] Email: [email protected] Telephone: 011 789 9495 Facsimile: 011 789 9498

The information contained in this report is relevant only to the sample/samples supplied to WATERLAB (Pty) Ltd. Any further use of the above information is not the responsibility or liability of WATERLAB (Pty) Ltd. Except for the full report, parts of this report may not be reproduced without written approval of WATERLAB (Pty) Ltd.

Page 1 of 6

Building D, The Woods, Persequor Techno Park, Meiring Naudé Road, Pretoria P.O. Box 283, 0020

Acid – Base Accounting Modified Sobek (EPA-600)

Sample Identification

BH4 S2 BN4 S4 BN8 S4 BN8 S1/S2

Sample Number 5755 5756 5757 5758

Paste pH 4.6 6.2 5.3 6.5

Total Sulphur (%) (LECO) 1.43 1.00 0.30 2.26

Acid Potential (AP) (kg/t) 44.69 31.25 9.38 70.63

Neutralization Potential (NP) -1.78 20.11 -1.27 4.86

Nett Neutralization Potential (NNP) -46.46 -11.14 -10.64 -65.77

Neutralising Potential Ratio (NPR) (NP : AP) 0.04 0.64 0.13 0.07

Rock Type I I I I



BN8 SST BN9 S2 BN9 S4 BN9 SST

Sample Number 5759 5760 5761 5762

Paste pH 5.2 6.6 7.3 6.0



Neutralization Potential (NP) -5.35 22.71 -1.11 3.33



Rock Type III I II I


WATERLAB (PTY) LTD






Page 2 of 6




BN11 S4 BN11 SST BN11 SST BN14 S4 BN14 S2

Sample Number 5763 5764 5764D 5765 5766

Paste pH 4.1 5.3 5.9 4.7 4.9

Total Sulphur (%) (LECO) 1.30 0.14 0.14 0.11 1.75

Acid Potential (AP) (kg/t) 40.63 4.38 4.38 3.44 54.69

Neutralization Potential (NP) -2.80 0.78 -0.76 -1.78 -2.03

Nett Neutralization Potential (NNP) -43.42 -3.60 -5.13 -5.21 -56.72

Neutralising Potential Ratio (NPR) (NP : AP) 0.07 0.18 0.17 0.52 0.04

Rock Type I II II II I



BN14 SST BN18 S4 BN18 SST BN22 SST

Sample Number 5767 5768 5769 5770

Paste pH 4.0 5.4 6.6 5.4

Total Sulphur (%) (LECO) 0.36 0.16 <0.01 0.27


Neutralization Potential (NP) -2.80 -3.31 -4.07 -2.54



Rock Type I II III I


WATERLAB (PTY) LTD






Page 3 of 6




BN23 S1/S2

BN26 S1/S2 BN26 S4 BN26 SST BN26 SST

Sample Number 5771 5772 5773 5774 5774D

Paste pH 6.1 6.3 4.4 6.2 6.3

Total Sulphur (%) (LECO) 0.47 3.84 0.13 0.06 0.06

Acid Potential (AP) (kg/t) 14.69 120.00 4.06 1.88 1.88

Neutralization Potential (NP) -0.50 0.27 -0.25 -1.01 0.01

Nett Neutralization Potential (NNP) -15.19 -119.74 -4.31 -2.88 -1.87

Neutralising Potential Ratio (NPR) (NP : AP) 0.03 0.00 0.06 0.54 0.01

Rock Type I I II II II



BN29 S4 BN29 SST

Sample Number 5775 5776

Paste pH 4.0 5.3

Total Sulphur (%) (LECO) 1.35 0.60

Acid Potential (AP) (kg/t) 42.19 18.75

Neutralization Potential (NP) -2.54 -2.03

Nett Neutralization Potential (NNP) -44.73 -20.78

Neutralising Potential Ratio (NPR) (NP : AP) 0.06 0.11

Rock Type I I

• Negative NP values are obtained when the volume of NaOH (0.1N) titrated (pH:8.3) is greater than the volume of HCl (1N) to reduce the pH of the sample to 2.0 – 2.5 Any negative NP values are corrected to 0.00.

Please refer to Appendix (p.4) for a Terminology of terms and guidelines for rock classification


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APPENDIX : TERMINOLOGY AND ROCK CLASSIFICATION

TERMINOLOGY (SYNONYMS)

� Acid Potential (AP) ; Synonyms: Maximum Potential Acidity (MPA) Method: Total S(%) (Leco Analyzer) x 31.25

� Neutralization Potential (NP) ; Synonyms: Gross Neutralization Potential (GNP) ; Syn: Acid Neutralization Capacity (ANC) (The capacity of a sample to consume acid) Method: Fizz Test ; Acid-Base Titration (Sobek & Modified Sobek (Lawrence) Methods)

� Nett Neutralization Potential (NNP) ; Synonyms: Nett Acid Production Potential (NAPP) Calculation: NNP = NP – AP ; NAPP = ANC – MPA

� Neutralising Potential Ratio (NPR) Calculation: NPR = NP : AP

CLASSIFICATION ACCORDING TO NETT NEUTRALISING POTENTIAL (NNP)

If NNP (NP – AP) < 0, the sample has the potential to generate acid If NNP (NP – AP) > 0, the sample has the potential to neutralise acid produced

Any sample with NNP < 20 is potentiall acid-generating, and any sample with NNP > -20 might not generate acid (Usher et al., 2003)

ROCK CLASSIFICATION

TYPE I Potentially Acid Forming Total S(%) > 0.25% and NP:AP ratio 1:1 or less

TYPE II Intermediate Total S(%) > 0.25% and NP:AP ratio 1:3 or less

TYPE III Non-Acid Forming Total S(%) < 0.25% and NP:AP ratio 1:3 or greater


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CLASSIFICATION ACCORDING TO NEUTRALISING POTENTIAL RATIO (NPR)

Guidelines for screening criteria based on ABA (Price et al., 1997 ; Usher et al., 2003)

Potential for ARD Initial NPR Screening

CriteriaComments

Likely < 1:1 Likely AMD generating

Possibly 1:1 – 2:1 Possibly AMD generating if NP is insufficiently reactive or is depleted at

a faster rate than sulphides

Low 2:1 – 4:1 Not potentially AMD generating unless significant preferential exposure

of sulphides along fracture planes, or extremely reactive sulphides in

combination with insufficiently reactive NP

None >4:1 No further AMD testing required unless materials are to be used as a

source of alkalinity

CLASSIFICATION ACCORDING TO SULPHUR CONTENT (%S) AND NEUTRALISING POTENTIAL RATIO (NPR)

For sustainable long-term acid generation, at least 0.3% Sulphide-S is needed. Values below this can yield acidity but it is likely to be only of short-term significance. From these facts, and using the NPR values, a number of rules can be derived:

1) Samples with less than 0.3% Sulphide-S are regarded as having insufficient oxidisable Sulphide-S to sustain acid generation.

2) NPR ratios of >4:1 are considered to have enough neutralising capacity. 3) NPR ratios of 3:1 to 1:1 are consider inconclusive. 4) NPR ratios below 1:1 with Sulphide-S above 3% are potentially acid-generating. (Soregaroli & Lawrence, 1998 ;

Usher et al., 2003)


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REFERENCES

LAWRENCE, R.W. & WANG, Y. 1997. Determination of Neutralization Potential in the Prediction of Acid Rock Drainage. Proc. 4th International Conference on Acid Rock Drainage. Vancouver. BC. pp. 449 – 464.

PRICE, W.A., MORIN, K. & HUTT, N. 1997. Guidelines for the prediction of Acid Rock Drainage and Metal leaching for mines in British Columbia : Part 11. Recommended procedures for static and kinetic testing. In: Proceedings of the Fourth International Conference on Acid Rock Drainage. Vol 1. May 31 – June 6. Vancouver, BC., pp. 15 – 30.

SOBEK, A.A., SCHULLER, W.A., FREEMAN, J.R. & SMITH, R.M. 1978. Field and laboratory methods applicable to overburdens and minesoils. EPA-600/2-78-054. USEPA. Cincinnati. Ohio.

SOREGAROLI, B.A. & LAWRENCE, R.W. 1998. Update on waste Characterisation Studies. Proc. Mine Design, Operations and Closure Conference. Polson, Montana.

USHER, B.H., CRUYWAGEN, L-M., DE NECKER, E. & HODGSON, F.D.I. 2003. Acid-Base : Accounting, Techniques and Evaluation (ABATE): Recommended Methods for Conducting and Interpreting Analytical Geochemical Assessments at Opencast Collieries in South Africa. Water Research Commission Report No 1055/2/03. Pretoria.

ENVIRONMENT AUSTRALIA. 1997. Managing Sulphidic Mine Wastes and Acid Drainage.


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CERTIFICATE OF ANALYSES SULPHUR SPECIATION

ASTM E 1915 – Hot Hydrochloric Acid Method ASTM E 1915 – Hot Nitric Acid Method

Methods from: Prediction Manual For Drainage Chemistry from Sulphidic Geological Materials MEND Report 1.20.1




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Sulphur Speciation Sample Identification

BH4 S2 BN4 S4 BN8 S4 BN8 S1/S2

Sample Number 5755 5756 5757 5758


Sulphate (SO42-) Sulphur (%) 0.51 0.42 0.06 <0.01

Sulphide (S2-) Sulphur (%) 0.88 0.58 0.20 2.26


BN8 SST BN9 S2 BN9 S4 BN9 SST

Sample Number 5759 5760 5761 5762


Sulphate (SO42-) Sulphur (%) 0.06 0.30 0.08 0.04



BN11 S4 BN11 SST BN14 S4 BN14 S2

Sample Number 5763 5764 5765 5766


Sulphate (SO42-) Sulphur (%) 0.09 0.13 0.05 0.67

Sulphide (S2-) Sulphur (%) 1.10 <0.01 0.04 1.08


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CERTIFICATE OF ANALYSES SULPHUR SPECIATION

ASTM E 1915 – Hot Hydrochloric Acid Method ASTM E 1915 – Hot Nitric Acid Method

Methods from: Prediction Manual For Drainage Chemistry from Sulphidic Geological Materials MEND Report 1.20.1




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BN14 SST BN18 S4 BN18 SST BN22 SST

Sample Number 5767 5768 5769 5770

Total Sulphur (%) (LECO) 0.36 0.16 <0.01 0.27

Sulphate (SO42-) Sulphur (%) 0.08 0.11 <0.01 <0.01

Sulphide (S2-) Sulphur (%) 0.28 0.05 <0.01 0.27


BN23 S1/S2 BN26 S1/S2 BN26 S4 BN26 SST

Sample Number 5771 5772* 5773 5774*


Sulphate (SO42-) Sulphur (%) 0.04 <0.01 0.10 0.01



BN29 S4 BN29 SST

Sample Number 5775 5776

Total Sulphur (%) (LECO) 1.35 0.60

Sulphate (SO42-) Sulphur (%) 0.54 0.37

Sulphide (S2-) Sulphur (%) 0.78 0.19

* Sample analysed with cold methods, according to EPA 600 (Hydrochloric Acid Method) and EPA 600 (Nitric Acid Method). Methods from: Prediction Manual for Drainage Chemistry from Sulphidic Geological Materials MEND Report 1.20.1

hydrogeological assessment for the ......2 709 420 1 129 13.07 3 860 428 1 288 14.91 4 639 1 164 1...

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