de beers consolidated mines (pty) limited - …...the agreement between de beers consolidated mines...

October 2017

DE BEERS CONSOLIDATED MINES (PTY) LIMITED - VOORSPOED MINE

Summary of Surface and Groundwater Study for Mine Closure

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Report Number: 1663605-316475-5

Distribution:

1 x eCopy Voorspoed Mine.

1 x eCopy [email protected].

Submitted to:

De Beers Consolidated Mines (Pty) Ltd Voorspoed Mine PO Box 1964 KROONSTAD 9500

(91 Gol4er Associates

DBCM - ENQUIRY NO.: VS-E-085-16

October 2017 Report No. 1663605-316475-5 i

Table of Contents

1.0 INTRODUCTION ........................................................................................................................................................ 1

2.0 OBJECTIVES ............................................................................................................................................................ 1

3.0 PROJECT ADMINISTRATION .................................................................................................................................. 1

4.0 HISTORICAL STUDIES ............................................................................................................................................. 2

4.1 Gaps identified during previous modelling work ........................................................................................... 2

4.2 Way forward (from preceding studies) .......................................................................................................... 3

5.0 GEOHYDROLOGICAL INVESTIGATIONS ............................................................................................................... 3

5.1.1 Voorspoed Mine Geological Model ......................................................................................................... 3

5.1.2 Groundwater Quality Assessment (incl. surface ponds) .......................................................................... 4

5.1.3 Groundwater levels and flow directions ................................................................................................. 14

5.2 Appendixes Related to the Hydrogeological Investigation .......................................................................... 17

5.3 Conceptual modelling ................................................................................................................................. 17

5.4 Conclusions and Recommendations (Hydrogeological Investigation) ........................................................ 22

6.0 GEOCHEMICAL ASSESSMENT ............................................................................................................................. 24

6.1 Previous Geochemistry studies .................................................................................................................. 24

6.2 Summary of Water Qualities Observed (near field area) ............................................................................ 24

6.3 Conceptual Model (geochemistry) .............................................................................................................. 25

6.4 Sampling and Laboratory Program ............................................................................................................. 26

6.5 Geochemical Test Results .......................................................................................................................... 27

6.6 Acid Base Accounting ................................................................................................................................. 27

6.7 Drainage Chemistry Analyses..................................................................................................................... 30

6.8 Waste Assessment and Classification ........................................................................................................ 32

6.9 Conclusions (Geochemical Assessment) ................................................................................................... 34

6.10 Appendixes Related to the Geochemical Assessment ............................................................................... 35

7.0 FLOOD LINE ASSESSMENT .................................................................................................................................. 36

8.0 DYNAMIC WATER AND SALT BALANCE ............................................................................................................. 38

8.1 Process Water Reticulation System Description ......................................................................................... 38

8.1.1 Water and waste storage facilities ........................................................................................................ 38

8.1.2 Water demand figures ........................................................................................................................... 41

8.2 Water Balance Modelling Methodology and Results ................................................................................... 41


October 2017 Report No. 1663605-316475-5 ii

8.3 Salt Balance................................................................................................................................................ 42

8.4 Conclusions and Recommendations (Water & Salt Balance) ..................................................................... 42

9.0 NUMERICAL GROUNDWATER FLOW AND CONTAMINANT TRANSPORT MODEL ......................................... 43

9.1 Applicable Conclusions (Numerical Modelling) ........................................................................................... 54

10.0 SYNOPSIS ............................................................................................................................................................... 55

11.0 REFERENCES ......................................................................................................................................................... 57

TABLES

Table 1: Project Team .............................................................................................................................................. 2

Table 2: Water quality guidelines ............................................................................................................................. 8

Table 3: Conceptual source-pathway-receptor characterisation for mine facilities at Voorspoed........................... 26

Table 4: Geochemical Abundance Index for waste rock, coarse residue and fine residue samples. ..................... 27

Table 5: Summary of the Dam Characteristics ....................................................................................................... 38

Table 6: FRDs Summary ........................................................................................................................................ 41

Table 7: Average Water Demands ......................................................................................................................... 41

Table 8: Source terms TDS concentrations............................................................................................................ 42

Table 9: Pit lake water quality range based on static test data............................................................................... 50

FIGURES

Figure 1: 2017 Hydrocensus survey points (with water level data). ......................................................................... 5

Figure 2: Piper Diagram illustration of the 2017 Hydrocensus monitoring sites at Voorspoed Mine. ....................... 6

Figure 3: Schoeller Diagram illustration of the 2017 Hydrocensus monitoring sites at Voorspoed Mine. ................. 7

Figure 4: Groundwater quality time series TDS concentration in borehole MBH02 at Voorspoed Mine. .................. 8

Figure 5: 2007-2016 time series TDS concentration (mg/l) in borehole VDBH01 at Voorspoed Mine, just SW of FRD (Class 1: WRC, 1998). .................................................................................................................... 9

Figure 6: 2007-2016 time series sodium [Na] concentration (mg/l) in borehole VDBH01 at Voorspoed Mine, just SW of .................................................................................................................................................... 10

Figure 7: 2007-2016 time series chloride [Cl] concentration (mg/l) in borehole VDBH01 at Voorspoed Mine, just SW of FRD. ........................................................................................................................................... 10

Figure 8: 2007-2016 time series fluoride [F] concentration (mg/l) in borehole VDBH01 at Voorspoed Mine, just SW of FRD ................................................................................................................................................... 11

Figure 9: Sulphate concentrations of boreholes at the FRD and downstream (MBH02). ....................................... 12

Figure 10: Fluoride (F) concentrations in the Voorspoed mine area, including the pit water (DBV Pit) .................. 13

Figure 11: Water level time series for borehole VBBH04, Voorspoed Mine ........................................................... 15

Figure 12: Water level & CRD Trends - VDBH04 ................................................................................................... 16

Figure 13: Water level & CRD Trends – MBH05 .................................................................................................... 16

Figure 14: Boreholes used for conceptual model design and illustration of secondary geological features (faults/dykes) on the Voorspoed mine site area. ................................................................................... 18


October 2017 Report No. 1663605-316475-5 iii

Figure 15: Voorspoed Mine 3D Conceptual Model (current operational phase) from the South and observed (2017) sulphate concentration levels (mg/l). .......................................................................................... 19

Figure 16: Operational phase conceptual model of the Voorspoed Pit (based on 2017 observations). ................. 20

Figure 17: Voorspoed Mine 3D Conceptual Model (post-closure scenario) from the South showing partially filled pit lake scenario. ................................................................................................................................... 21

Figure 18: Post operational phase conceptual model of the Voorspoed Pit (~50 years after closure). .................. 22

Figure 19: Location of mine waste, seepage and water samples ........................................................................... 29

Figure 20: Plot of NAG pH versus TNPR (Bulk NP/TAP) of coarse and fine residue and waste rock. ................... 30

Figure 21: Piper diagram of waste rock, processed waste rock seepages and pit water samples. ........................ 31

Figure 22: Voorspoed Mine - Perennial and Non-perennial Streams ..................................................................... 37

Figure 23: Voorspoed mine water reticulation system showing monthly water meter figures (viz. minimum, average and maximum). ........................................................................................................................ 40

Figure 24: Inflows to the Voorspoed Mine pit simulated between 2008 and 2017. ................................................. 44

Figure 25: Time series water level data and simulated water level at monitoring site VDH04 (wrongly numbered VBH04) .................................................................................................................................................. 45

Figure 26: Operational hydraulic head distribution (as per 2017 prediction) .......................................................... 46

Figure 27: Simulated drawdown and cone of depression of the Voorspoed Mine site area (as per 2017 hydrocensus processing) ...................................................................................................................... 47

Figure 28: Prediction of the Voorspoed Pit Lake development after closure. ......................................................... 48

Figure 29: Schematic of the Voorspoed Mine post operational pit lake development ............................................ 49

Figure 30: Simulated sulphate (SO4) plume development from post closure phase – after 5, 10, 15 and 30 years. .................................................................................................................................................... 52

Figure 31: Simulated sulphate (SO4) plume development from post closure phase – after 50, 100, 150 and 200 years ..................................................................................................................................................... 53

APPENDICES

APPENDIX A Document Limitations


October 2017 Report No. 1663605-316475-5 1

1.0 INTRODUCTION

De Beers Consolidated Mines (Pty) Limited’s Voorspoed diamond mine situated in the north-eastern Free

State Province, is approaching its mining operations closure phase (approximately four years ahead). In

preparation for closure permitting, a surface and groundwater study for mine closure requirements covering

the following disciplines were conducted:

i) a geohydrological assessment (groundwater flow and quality), incl. a conceptualization and a

numerical flow and transport model,

ii) a geochemistry study assessment (characterisation of potential contaminant sources to surface and

groundwater resources),

iii) a dynamic water balance model (including user interface which enables the user to update inputs, run

the model and view the results of the simulations; and

iv) a hydrological assessment of potential flood line risks (to confirm the status of perennial/non-perennial

streams in the area).

2.0 OBJECTIVES

In terms of preparing for mine closure status, the following objectives were addressed and investigated as

part of the surface and groundwater study:

A review and assessment of the existing hydrogeological and hydrogeochemical data collated during

previous studies and important observations made in these studies;

Identification of information/data gaps [gap analyses] and address to optimise the surface and

groundwater characteristics of the Voorspoed mine site and surrounding area (~3-5 km

radii);hydrogeological and geochemical aspects;

Undertake a geochemical characterisation (waste assessment and waste classification) of the fine and

coarse tailings deposits and waste rock dump;

Conduct a baseline groundwater situation/status assessment of the mine and surrounding area

(hydrocensus survey and water quality assessment of the mine site and surrounding area); and

Develop a representative conceptualization of the groundwater characteristics on the mine site and

immediate surrounding area based on the available datasets.

Develop a numerical groundwater flow model and contaminated transport model to aid in the post

closure contamination of the aquifers proximal to the mine and post mine lake characteristics;

Develop a long-term dynamic water balance and a salt balance for the mine; and

Undertake a [desktop] flood line assessment on the Voorspoed mine site area.

Based on the CGwM, draft a conceptual source-pathway-receptor model (SPRM) for the mine site.

Prepare a post mining monitoring programme which specifically addresses the mine closure

requirements by Departments of Water and Sanitation and Mineral Resources.

The main objective, therefore, is to update the hydrological and geochemical status and conditions at the

Voorspoed Mine consequently to ensure mine closure requirements are addressed and post mining

hydrological1 status is well monitored and maintained within the closure conditions and limits.

3.0 PROJECT ADMINISTRATION

The agreement between De Beers Consolidated Mines (Pty) Limited and Golder Associates Africa (Pty) Ltd

was signed on the 14th March 2017 and preparations for the hydrocensus work started within a week after

signing the agreement. Induction of the Golder staff member, conducting the hydrocensus were done in

1 Surface water and groundwater components.



January 2017 already, however, all field activities were stopped due to fact that the agreement was not

legally finalised.

The first “onsite” project initiation meeting were conducted on the 6th of April 2017. A presentation of the

project objectives and approaches was presented by the Golder Team. The Golder Team, at this stage was

selected and is listed in Table 1 below.

Table 1: Project Team

Golder Team Designation Qualification

Senior Hydrogeologist & Project Manager – Technical Reviewer

Eddie van Wyk PhD. (Pr.Sci.Nat. – 400121/10),

Senior Geochemist – Technical Reviewer

David Love PhD, FWISA)

Principal Water Resource Engineer

Trevor Coleman Pr Eng, BSc (Civ Eng), MSc (Eng)

Geochemist Keretia Lupankwa PhD - Env. Geology

Hydrogeologist/Numerical Modeller

Talita Germishuyse (Megan Hill)

MSc (Geohydrology), Pr. Sci. Nat.

Hydrogeologist Lukas Marais (Intern) MSc. Hydrogeology

Water Resource Engineer Dorcas Adjei-Sasu (Amelia Basson)

BSc. Civil Engineering

Two Golder “in-house” team meetings were held during April and May; mainly to discuss the outcome of

our internal data/information Gap analysis process and identification of outstanding data/information.

Several short “one-to-one” discussions are conducted on an ongoing bases where specific aspects of the

project are discussed/planned.

The project team is virtually the same group that has been proposed in the original proposal, except for

Megan Hill (replaced by Ms Talita Germishuyse) and Amelia Basson (replaced by Dorcas Adjei-Sasu).

4.0 HISTORICAL STUDIES

Historical water related investigations undertaken at Voorspoed mine include;

Geocon on behalf of Metago (2004) Geohydrological specialist investigation at the De Beers

Voorspoed Diamond Mine, Report No. G/R/04/10/12;

Hydrologic Consultants, Inc. (HCI), 2004. Predicted ground-water conditions at proposed

Voorspoed Mine based on preliminary ground-water flow modelling. Report prepared by Hydrologic

Consultants, Inc., for KLM Consulting Services (Pty) Ltd., August; and

Itasca Denver, Inc. (2014) Predicted Groundwater Conditions at Voorspoed Mine, Report No. #1809.

Numerical modelling was undertaken concurrently by Geocon and HCI in 2004. The purpose of the two

models were to forecast the groundwater conditions associated with mining activities during the operational

phase of mining.

4.1 Gaps identified during previous modelling work

The following gaps have been identified during the preliminary Voorspoed data/information [gap]

assessment and they are:

As highlighted in Geocon in 2004 and in Itasca in 2014 uncertainty exists over the hydraulic

parameters of the rock/formation units proximal to the Voorspoed pit;

The mass transport plumes associated with the tailings facility were not simulated for the period post

closure and hence no modelling work currently (2017) exists to describe post closure mass transport;



mitigation requirements, and time series monitoring datasets (specifically, the for area outside the

Voorspoed mine site area); and

The existing models provide no insight of the pit lake conditions likely to develop in the post closure

era (i.e. the rate of filling, the possibility for decant (although unlikely) and the water quality).This type

of information is crucial for guiding the closure process.

During the project period, these gaps were addressed and improved, however, specific ones such as the

actual water quality signature of the [slow re-watering of the] pit lake requires a detailed assessment of the

pit sidewall-rock formation(s) and the anticipated local pit catchment area.

4.2 Way forward (from preceding studies)

Important aspects have been identified during the review of the previous reports and information of the

Voorspoed Mine and tabled for this study, and probably future assessments as well. They are:

In order to develop flow and particle transport models on which mine closure can be achieved it is

necessary that the data gaps previously identified are addressed/closed……..for this current study, all

available data has been collated and incorporated into the 2017 conceptual model of the mine site

area and a number of long-term time series assessments (viz. water levels and water quality trends)

were possible;

While Geocon (2004) previously undertook a hydrocensus in a 6 km radius of the mine, it was

deemed necessary that the hydrocensus be updated. The purpose of the update is to;

Determine if additional potential receptors occur within the study area; and

If water uses have altered over the past decade.

A borehole hydrocensus has been conducted in April 2017 and at least 12 boreholes have been surveyed

outside the Voorspoed Mine Site area of which eight (8) could be recorded (i.e. water level and/or water

quality)

As described above, it was necessary to develop a calibrated numerical model which can be utilised

to simulate mass transport associated with the tailings during the post operational phase. Through

development of such a model, appropriate mitigations strategies can be developed and a suitable

monitoring network established to guide closure.

A model should be developed which can assist in forecasting the actual hydrological and geochemical

characteristics of the pit lake during post mine-closure times(i.e. pit lake water balance, water level

elevation trends, bulk water quality characteristics and impact(s) of long-term evaporation losses) (not

included in this study). Through gaining understanding the hydrological characteristics of a Pit Lake it

can then be determined if the pit will remain a legacy or liability during the post operational phase of

mining and appropriate mitigation strategies can be suggested.

The different components of the mine closure study are summarised as follows (where applicable,

supporting explanations of these components are included, however, references to the main reports are

made subsequently).

5.0 GEOHYDROLOGICAL INVESTIGATIONS

A hydrocensus survey was conducted in April 2017 on the Voorspoed mine site area and in an area ~3-

5 km’s outside the mine site area (mainly private land). The purpose of the hydrocensus survey was to re-

located all available boreholes and other important water resources and update the hydrological

characteristics of time series datasets that are available. The hydrocensus, therefore focussed on the

“impacted” area (source areas) and the non-impacted areas (potential receptors).

5.1.1 Voorspoed Mine Geological Model

The geological model of the Voorspoed mine is described in detail in the Golder Groundwater Model Report

(Rep. No. 1663605-315698-2, sections 2.4 and 2.5). The conceptual groundwater model is based on the



available borehole drill log sheets and models described in the historical reports of the site. An updated

conceptual model of the Voorspoed Mine (viz. Kimberlite Pipe) is described in section 5.3 below.

5.1.2 Groundwater Quality Assessment (incl. surface ponds)

A total of sixteen water samples were collated during the hydrocensus survey and was submitted to the

Exova Jones Environmental Laboratory in Somerset West (SA) and Deeside (UK). Samples were analysed

and a SANAS accredited analytical report was submitted to Golder on the 3rd of May 2017. The positions of

the boreholes covered during the 2017 Golder hydrocensus survey is shown in Figure 1 below.

Water quality analyses of the sampled groundwater is shown in Figure 2 (Piper Diagram presentation) and

Figure 3 (Schoeller Diagram presentation). These diagrams also include a “Pit Water Sample” (Pit-W) and

seepage samples from the FRD (fine residual deposits), CRD (course residual dump), RWD (raw water

dam) sites.

The Piper Diagram reports natural groundwater quality evolution from the recently recharged waters (left-

hand quadrant of the Piper Diamond) characterised by a Ca/Mg-HCO3 signature to water representative of

dynamic flow, characterised by a Na-HCO3 signature and gradually towards a typical deep Karoo water

quality signature, characterised by Na-Cl (right-hand quadrant of the Piper Diagram). Stagnant

groundwater, or groundwater impacted by industrial/mining activity where elevated levels of chloride (Cl)

and sulphate (SO4) plots towards the top quadrant of the Piper Diamond – or very stagnant deep

groundwater.

The “Pit Water” quality Piper plot portrays a Na-SO4 water quality signature. Similarly, water samples

associated with the Coarse Residue Dumps and Fine Residue Dumps, plot as Na-Cl water types. This

likely indicates a [natural] source of sodium chloride associated with the Kimberlite pipe – associated with

the background hydrochemical signature of Karoo sedimentary formations, i.e. a primary elevated

constituent. Although the Pit Water, FRD, CRD and RWD have high levels of sulphate, the background Na-

Cl signature of the Karoo aquifers still, therefore, dominates the water quality signature in the area.



Figure 1: 2017 Hydrocensus survey points (with water level data).



Most of the groundwater quality sampled outside the mine site area, plots in the Ca/Mg-HCO3 quadrant and

represent the upper, shallower part of the aquifer system, which receive frequent rainwater recharge and not

impacted by mining/agricultural activities. Two monitoring sites (GL 1 and GL 2, located towards the western

Far Field Area reports elevated Na-Cl concentrations. The reason(s) for this is not clear, but could be related

to an agricultural related source and is unlikely associated with the mine due to the distance between the

mine and these boreholes.

To conclude, the groundwater quality from the mine site area have slightly elevated salinity levels (TDS ~750

mg/l) compared to the surrounding far field Area (viz. < 500 mg/l TDS).

Figure 2: Piper Diagram illustration of the 2017 Hydrocensus monitoring sites at Voorspoed Mine.

The Schoeller Diagram just reiterates the groundwater quality signatures as noted in the Piper Diagram,

however, the significance of the different water quality criteria (viz. Ca/Mg-HCO3, Na-HCO3 and Na-Cl) is

noted. One should note the strong signatures of HCO3, Na, Cl and SO4 for that matter.

Most of the water sources plots within a Class 0 (Ideal) and Class 1 (Good) with some constituents plots in

the Class 2 (Marginal) categories. To note is the elevated NO3 (as N) concentrations in for the RWD, F&CRD

and the Pit Water (i.e. ~49 mg/l as N).

The poor water quality condition at monitoring site GL2 (── in Figure 3) in the far field area is probably due

to local agricultural activity/pollution. Of all the monitoring points analysed, this site has the highest dissolved

mineral content, and is in fact an anomaly in the area. Due to the distance from the mine site area, the GL2

site has no relation to the mine site area and is regarded as a local [agricultural] impacted case.



Figure 3: Schoeller Diagram illustration of the 2017 Hydrocensus monitoring sites at Voorspoed Mine.

As mentioned above, groundwater in the far field area is used for domestic supplies and livestock watering.

The water quality guidelines applicable for these uses are summarised in

A medium-term (~5-10 years) water quality (viz, salinity as TDS in mg/l) time series plot of borehole MBH02

(or VD-BH2) is illustrated in Figure 4 and shows a steady increase in the water salinity concentration. This

boreholes lie outside the mine site area and indicate a rising trend in the hydrochemistry signatures. Initial

values in February 2007 were around the 450 mg/l level and dropped to ~350 mg/l during the 2009-2011

wetter rainfall cycles, before starting with a gradual increase towards the ~550 mg/l salinity level. The

hydrochemical constituents causing this rise is sodium and total hardness [as the chloride and sulphate

concentrations are respectively ~50 and ~35 mg/l]. This observation is, however, rather important and should

be seen as a potential risk for the surface water system downstream of the Voorspoed mine site area. The

physical risk should be quantified as part of the 2017 Hydrological Monitoring Program for Voorspoed Mine

[Closure].



Table 2: Water quality guidelines

Constituent/ Guideline

Chloride (mg/l) Sulphate (mg/l) Sodium (mg/l) Nitrate (mg/l) TDS (mg/l)

Baseline Limit* 48 27 123 43** 902

Drinking water Limits (SANS 241: 2015)

300 (250) 500 200 49 1200

Livestock Limits (Cattle) (DWAF, 2006)

3000 1000 2000 885 2000

*Baseline data taken from Geocon 2004

**Baseline Nitrate is high likely owing to livestock contamination

Figure 4: Groundwater quality time series TDS concentration in borehole MBH02 at Voorspoed Mine.

Other monitoring sites on the Voorspoed mine site area situated close to potential source areas, such as

monitoring site VDBH01 (also referenced as VDBH1), reports a rising trend in TDS values due to rising Na

and Cl concentrations as illustrated in Figure 5, Figure 6 and Figure 7 below.



Figure 5: 2007-2016 time series TDS concentration (mg/l) in borehole VDBH01 at Voorspoed Mine, just SW of FRD (Class 1: WRC, 1998).

Detailed evaluation of the spatial distribution of chloride (Cl), sodium (Na), sulphate (SO4), and total

dissolved solids (TDS) is covered in section 3.5 of the Golder Report: Hydrogeological Investigation, No.

1663605-315698-2).



Figure 6: 2007-2016 time series sodium [Na] concentration (mg/l) in borehole VDBH01 at Voorspoed Mine, just SW of

Figure 7: 2007-2016 time series chloride [Cl] concentration (mg/l) in borehole VDBH01 at Voorspoed Mine, just SW of FRD.



With reference to the fluoride concentrations in the Voorspoed mine site area, the following aspects are

relevant:

The background fluoride concentrations is Karoo groundwater are high. Research work on the fluoride

concentrations indicates value of between 2 and 6 mg/l are common. The 2017 Pit Water analysis

indicates a concentration level of 1.3 mg/l, and all the boreholes on the site area covered during the

2017 hydrocensus survey varies between 0.3 mg/l and 0.9 mg/l;

A Time Series plot of the Fluoride concentrations at Monitoring Site VDBH1, situated just upstream of

the FRD site is illustrated in Figure 8 below. It is obvious that there is virtually no trend in the fluoride

concentration level and the average value (~0.45 mg/l F) is that of a Class 0, Ideal water quality. The

fluoride value during the 2017 hydrocensus survey was 0.4 mg/l;

A map of the fluoride concentrations observed during the 2017 hydrocensus is illustrated in Figure 10

below. The Pit Water concentration is the only one that is above the long-term threshold of 1.0 mg/l.The

fluoride concentration levels in the mine site area (excluding the Pit Water) and the surrounding farm

lands are below 1.00 mg/l as indicated in Figure 10; and

The origin of fluoride in groundwater is generally related to (i) weathering and dissolution of fluoride

containing minerals such as apophyllite in zeolites, and (ii) deep circulating groundwater (viz. along

deep vertical structure such as dolerite dykes and Kimberlite fissures/pipes for example). The

concentrations of the Pit Water sample is in fact too low to indicate a deep water source (normally these

fluoride concentrations are in the order of 6 to 10 g/l and unless significantly diluted by local direct

[rainfall] recharge into the pit area.

Figure 8: 2007-2016 time series fluoride [F] concentration (mg/l) in borehole VDBH01 at Voorspoed Mine, just SW of FRD



In terms of the sulphate concentration on the Voorspoed mine site area, a detailed discussion thereof of

appear under section 3.5 (viz. Hydrochemistry) of the Hydrogeological Investigation (Golder Report No.

1663605-315698-2). Sulphate was selected as there are no other sources of sulphate proximal to the mine

with the exception of the dumps and hence sulphate is a suitable tracer of mine seepage. A detailed long-

term monitoring has been undertaken at several boreholes both far and near field area, however, the results

conclude that:

That sulphate concentrations at all monitoring sites, except private borehole GL2 (west of the mine site

area) do not exceed the WRC (WRC et al, 1998) drinking water quality limits for sulphate. Thus in terms

of sulphate, the water quality is not deemed to be impacted severely.

Detailed discussion of the long-term monitored sulphate concentrations with time series sulphate

concentrations illustrations at high risk areas, i.e. (i) the waste rock dump (WRD), (ii) course residue dumps

(CRD), and (iii) fine residue dump (CRD) appears on pages 39 to 41 of the above-mentioned groundwater

modelling report (section 3.5). The sulphate concentration [trends] observed in the vicinity of the FRD is

illustrated in Figure 9 below, and although the concentrations are still at Class 0 (viz. Ideal water quality), a

long-term rising trend is present at some boreholes, i.e.

The near field borehole VDBH01 (see Figure 1) was found to gradually be increasing over time. This is

expected as this borehole is on the flow pathway trajectory between the FRD and open pit; and

Similarly a gradual increasing sulphate trend is observed at far field borehole MBH02 (see Figure 1),

which possibly indicates that a plume associated with the FRD is impacting on this borehole via the

small drainage system flowing from the RWD and SWCD (see Figure 10 below).

Figure 9: Sulphate concentrations of boreholes at the FRD and downstream (MBH02).



Figure 10: Fluoride (F) concentrations in the Voorspoed mine area, including the pit water (DBV Pit)



5.1.3 Groundwater levels and flow directions

A detailed discussion of the groundwater levels (boreholes) appears in section 3.3 of the groundwater

modelling report (Golder Report: Hydrogeological Investigation, No. 1663605-315698-2).

The main aspects of the groundwater levels in far and near field areas of the Voorspoed mine site area, are

as follows:

Water levels on the surrounding farms represented both static and dynamic levels and ranged between

2 mbgl and > 30 mbgl.

Boreholes BH 31 and BH 32 (3.3 km west-south-west of the pit) located on Siding 1568 displayed deep

water levels (> 30 mbgl). However, deep water levels were also measured at the boreholes in 2004

indicating that mine dewatering is unlikely the cause and rather the deep water levels are probably a

consequence of groundwater abstraction for livestock watering and domestic use.

At the time of the census, the pit was at a depth of 1193 mamsl (217 mbgl). The water levels at

boreholes located adjacent to the pit; GDH1602 and GDH 1601 are 53 mbgl and 38 mbgl respectively.

This indicates that the cone of depression associated with the pit is steep and has limited lateral impact.

Water levels in boreholes proximal to the tailings were found to be shallow (< 7 mbgl) which are inferred

to be a result of the effects of seepage from these facilities.

Proximal to the pit groundwater is expected to flow toward the pit due to the effects of evaporation on

the pit area. North of the dumps, groundwater flows north and north easterly from the dump areas.

While south of the mine flow occurs in a south – south westerly flow direction.

A time series water level hydrograph observed at monitoring site VDBH04 (situated on the eastern,

downstream area of the Voorspoed mine site area as shown in Figure 10 above) is illustrated in Figure 11

below, and:

Water level has recovered since it was [probably] used for water supplies prior to 2011;

Water level indicates a slight downward trend (viz. water level recession) since May 2011; and

Moderate aquifer storage response (water table rebounds) following high rainfall events in October-

November 2007, January-February 2010, and October-November 2011.

Water table time series data does not indicate local “dewatering” impacts of the Voorspoed mining

taking place on the mine site area.

VDBH04 is located 400 m from the foot of the coarse waste rock dump. Based on measured water

levels and inferences from topography, groundwater is expected to flow from the waste rock dump

toward this borehole and therefore explains the shallower water table conditions wrt the CRD

simulation. The water level trend at this site closely represent the CRD trend; and

MBH01 - MBH05 are located on adjacent properties north and north east of the mine. With the

exception of MBH01 and MBH 05, the boreholes have sporadically been monitored and consequently

data interpretation is limited. MBH01 and MBH 05 both closely correlate with the CRD trend.



Figure 11: Water level time series for borehole VBBH04, Voorspoed Mine

The water levels have been compared against the cumulative rainfall departure (CRD) in order to aid in

understanding the water level trends on site, as illustrated in Figure 12 and Figure 13 below.



Figure 12: Water level & CRD Trends - VDBH04

Figure 13: Water level & CRD Trends – MBH05



The following observations have been made from the water level dataset:

5.2 Appendixes Related to the Hydrogeological Investigation

Several appendixes containing processed time series water quality and water level datasets are attached to

the separate reports submitted during the project period, they are as follows:

Golder Report: Surface and Groundwater Study for Mine Closure Requirements, No. 1663605-314859-

1: Three appendixes containing the following processed datasets:

Appendix A: Groundwater and open (surface) water LAB certificates and analytical data;

Appendix B: Water Quality and Water Level Graphs; and

Appendix C: Waste chemistry LAB certificates and datasets (same as included in the Geochemical

Assessment Report (Golder Report No. 1663605-316224-4).

Golder Report: Hydrogeological Investigation, No. 1663605-315698-2: Two appendixes containing the

following processed datasets:

Appendix A.1: Fluoride time series graphs; and

Appendix A.2: Elemental chemistry time series graphs.

These are all time series plots of the available water hydrochemistry of the Voorspoed mine site area.

5.3 Conceptual modelling

The geology of the site was described by previous investigators; Geocon (2004), HCI (2004), Shangoni

(2011) and most recently by Itasca (2014) the descriptions presented are used as the basis for describing

the geology of the site below. A plan view of the borehole sites and information [from previous studies] used

in the design of the conceptual model is illustrated in Figure 14 below. The figure also shows the positions

and directions sub-vertical geological features, i.e. faults and dykes which could play a role in the “on-site”

groundwater flow regime.

The basic geological model of the Voorspoed Kimberlite feature and surrounding geology is depicted in

Figure 15 and Figure 17.The Voorspoed mine site area comprises of shales and mudstones of the Volksrust

formation (VRM) which are part of the Ecca Group of the Karoo Supergroup. The Volksrust formation is

underlain by coarser grained; conglomerates, shales and sandstones of the Vryheid formation (VRSSC).

Shale (VRVS) is found to occur at depth. The sedimentary package dips at approximatly150 toward the

north-north-west.

The strata has been intruded by dolerite dykes and sills. Three major sills were identified to intersect the pit,

namely;

Dolerite Sill (#14) (the number assigned in the GEMCOM model) - a sill with a thickness ranging from 1

to 25 m, but more commonly ranging from 3 to 8 m thick in the immediate mine area. The upper contact

zone of the sill is relatively permeable based on packer test data;

Dolerite Sill (#13) - a thicker sill with a thickness ranging from 20 to 180 m, more commonly ranging

from 80 to 120 m in the mine area; and

Dolerite Sill (#12) - a sill in the shale discovered by De Beers in exploration boreholes. The thickness of

this lower sill ranges from 10 to 65 m, most commonly being between 30 and 55 m.

The Kimberlite pipe on the farm Voorspoed 401 is an irregular, approximately oval shaped body. The

dimensions of the pipe are in the order of 490 m x 350 m. An essentially vertical body of Stormberg-age

basalt intruded into the southern part of the kimberlite pipe. The bottom of the basalt body has been

intersected at a depth 430 m below ground surface (Ref. Hydrogeological Investigation, Report No.

1663605-315698-2, section 2.4, Figure 4, page 5).



Figure 14: Boreholes used for conceptual model design and illustration of secondary geological features (faults/dykes) on the Voorspoed mine site area.



The following features of the 2017 conceptual model were noted:

The hydraulic parameters of the sedimentary sequence (Karoo Ecca Group) at Voorspoed Mine is low

to insignificant (i.e. based on previous aquifer investigations and test pumping);

Due to the low hydraulic characteristics of the surrounding Karoo Supergroup aquifer systems (viz.

shales and mudstones), the 2017 water table status indicates a limited development of a dewatering

cone due to the mining activity as indicated in Figure 15 below;

The role of [secondary] Karoo dolerite sills probably has a limited impact on the local groundwater flow

regime on the mine site area as this [intrusive] formation also has low to insignificant hydraulic features.

The dolerite-sedimentary contact zone (viz. metamorphosed due to the magma temperature, is

however limited to a small “contact aquifer” system, but obviously not a significant contributor to

groundwater flow in the pit area. These sills have a folder nature in the mine site area, but does not

impact significantly on the local flow regime (not specifically noted in the groundwater piezometric

surface dataset).

Figure 15: Voorspoed Mine 3D Conceptual Model (current operational phase) from the South and observed (2017) sulphate concentration levels (mg/l).

On the other hand, the role of sub-vertical dolerite dykes in the area as illustrated in Figure 14, has

been noted by local geologists and exploratory drilling has shown that high permeable flow paths are

present (i.e. narrow contact fractured water bearing zones) which could play a significant role in the

migration of groundwater [containing, or not-] from the mine site area. To verify this aspect, an upgrade

of the monitoring infrastructure and dedicated monitoring sites on the mine site area are planned for

2017-2018 and monitoring sites will be placed in these areas to monitoring the actual role these sub-

vertical water bearing zones might play during the post-mining period [based a dedicated monitoring

program].



However, during the 2017 hydrocensus and specific observations in the Voorspoed Pit [where the

above-mentioned features, as well as sub-vertical faults were mapped in the past] no significant water

ingress were noted on the side walls of the pit, a condition confirmed by Voorspoed staff (Pers. Comm.,

2017); and

Limited seepage takes place on the higher elevations in the pit sidewalls, but due to high evaporation in

the area, most of this water evaporates and does not report to the final water make at the pit bottom, as

indicated in Figure 15 above.

A close-up of the Voorspoed Pit hydrological status during operational times is illustrated in Figure 16 and

shows the different pit wall processes and the groundwater elevations in the country rock surrounding the pit

side wall. Based on the local water level observations, a large part of the pit sidewall acts as an unsaturated

zone where any seepages generated by direct rainfall recharge/groundwater seepage, is intercepted by

evaporation and subsequently diminishes long before it all accumulated in the pit sump. It indicates that:

Local seepages (e.g. from rainfall events) occurs near the upper fractured and weathered part of the pit,

and only during exceptional rainfall events, pit sidewall run-off reaches the base of the pit (i.e. as per

Google Image interpretations);

Rock materials in the open pit are likely to generate near neutral drainage with high total dissolved

solids, moderate sulphate and low concentration of trace elements upon exposure to rainfall; and

The drainage from the wall rock is likely to be similar to that of waste rock leachate in the long term, but

the concentrations will rise and fall with inflows and evaporation.

Figure 16: Operational phase conceptual model of the Voorspoed Pit (based on 2017 observations).



Based on the numerical modelling of the post mine closure phase, water starts too accumulated in the pit

and subsequently forms a pit lake, as illustrated in Figure 17. It is expected that under a partially filled pit

lake condition, the high evaporation uptake in the area will retain the pit lake water table at a negative water

balance, unless additional water ingress will be generated from a larger [engineered] pit lake catchment

area. Depending on the area (viz. hectares) of an engineered pit lake catchment [to enhance the water table

recovery for security reasons] the pit lake water table under normal climate conditions might never reach the

pristine piezometric water table.

Figure 17: Voorspoed Mine 3D Conceptual Model (post-closure scenario) from the South showing partially filled pit lake scenario.

A close-up of the processes that are relevant during a high elevation pit lake scenario, is illustrated in Figure

18 below. The following aspects have relevance [but is discussed in detail in Golder Report: Hydrogeological

Investigation, No. 1663605-315698-2 section 4.3.3.2, Post Closure Hydrochemistry with relation to plumes

associated with the WRD, CRD and FRD]. Basically the pit lake concept indicates that:

During the operational phase, solutes flushed by runoff and seepage from the wall rock are pumped

out;

Pumping of pit water will cease at the end of mining and solutes flushed from the wall rock will

accumulate in the pit;

It is expected that the mass of solutes added will be initially be high due to the large surface area of

exposed wall rock and will decrease with time as pit fills up and surface area of exposed wall rock

decreases; and

Once the water table equilibrates, inflows will be limited to rainfall and so concentrations are likely to

increase due to evaporation effect.



It is expected that stratification of the pit lake water body will developed over time, leaching in the

unsaturated zone (pit rim area) will continue indefinitely, and chemical reactions in the upper part of the

water body will take place due to the effects of evaporation (higher Salinity) and rainwater ingress (lower

salinity) will take place. As noted above, it is unlikely that the pit lake will reach a state where decanting will

take place under [existing] normal climate conditions – evaporation is just too high in relation with rainfall run-

off events.

Figure 18: Post operational phase conceptual model of the Voorspoed Pit (~50 years after closure).

5.4 Conclusions and Recommendations (Hydrogeological Investigation)

Conclusions:

The following conclusions were drawn from hydrogeological investigation:

The Voorspoed pit at life of mine will reach a final elevation of 1103 mamsl which equates to a pit depth

of 307 m. Throughout life of mine the inflow to the pit has been low owing the low permeability of

mudrocks, sandstones and shale which surrounding the kimberlite pipe.



Water level responses (i.e. rebounds) shows sharp rise in water level (> 15 m) that were seemingly

associated with significant recharge events. These types of fluctuations are common in low permeability

aquifers.

The cone of depression created through mining is consequently steep and limited in lateral/spatial

extent, 1.2 km to the west and terminates beneath the waste rock dump in the east and north

The water quality of boreholes on farms adjacent to the mine are presently not impacted by seepage

from the facilities nor from drawdown associate with the mining activities, i.e. open cast pit mining.

Corresponding with the seasonal fluctuations observed in the monitored water levels, recharge was

estimated to occur in the high rainfall summer months of the year and little to no recharge occurs in the

winter months.

Groundwater recharge across the study area is expected to be low. Average recharge for most of the

Karoo Supergroup is in the range of 2 to 3 % of MAP with a recurrence rate of 1 in 5 years of a

significant aquifer storage recharge event(s).

The key-potential impacts identified for the post closure phase of the operation is the pit lake rebound rate

and water quality and the migration of contaminant plumes associated with the dumps.

Pit Lake (reference to the numerical modelling part, see section 9.1 below as well)

Due to the low permeability of the country rock proximal to the Kimberlite pipe, the inflows to the pit are

low. Pit abstractions range between 0 l/s to 46.5 l/s (i.e. wetter periods with higher runoff inflow result in

higher abstraction rates).

Post operational hydrochemistry

The Piper Diagram shows a natural groundwater quality evolution from the recently recharged waters

characterised by a Ca/Mg-HCO3 signature to water representative of dynamic flow, characterised by a

Na-HCO3 signature and gradually towards a typical deep Karoo water quality signature, characterised

by Na-Cl.

The “Pit Water” quality Piper plot portrays a Na-SO4 water quality signature. Similarly, water samples

associated with the Coarse Residue Dumps and Fine Residue Dumps, plot as Na-SO4 water. This likely

indicates a natural source of sodium and sulphate associated with the Kimberlite pipe.

Most of the groundwater quality in the Far Field Area, plots in the Ca/Mg-HCO3 quadrant and represent

the upper, shallower part of the aquifer systems, which receive frequent rainwater recharge and is not

impacted by mine contamination.

With the exception of the TDS concentrations of the CRD all source concentrations are below the

livestock watering limit for the selected constituents. Sulphate, sodium and nitrate concentrations of the

sources tend to exceed drinking water quality limits and chloride exceeds the baseline water quality

limits.

Plumes associated with the WRD, FRD and CRD

Due to the effects of evaporation, the pit was found to remain as a sink during the post operational

phase of mining and as such a component of seepage from the WRD and FRD continued to be

captured by the pit.

However, due to the low permeability of the aquifer the radius of influence of the pit is limited and

consequently a component of seepage is expected to migrate downgradient toward the identified

receiving boreholes.

Recommendations

Re-design of the surface and groundwater monitoring infrastructure and programme to cover the study

area:



Specific reference of the surface water monitoring requirement (see discussion immediately above)

is required for the drainage running from the return water dam’s area towards the east.

Dedicated boreholes to monitor the shallow and deep aquifers individually are required especially in the

CRD area;

Establishment of a local weather station on the site; and

Prediction of the long-term evolution of pit lake water chemistry based upon the volume and chemistry

of surface run-off water channelled from the near filed areas to enhancement the pit lake water level

recovery, evaporative mass balance and a long-term mixing model.

6.0 GEOCHEMICAL ASSESSMENT

6.1 Previous Geochemistry studies

Metago Environmental Engineers (Pty) Ltd (2005) carried out an assessment of pollution potential of the

mine residue materials at Voorspoed on a limited number of samples, including one of kimberlite, as part of

the environmental management plan. Six waste rock samples with most carbonaceous bands were

subjected to South African Acid Rain Leach Test (SAAR) and elemental composition determination by X-ray

fluorescence (XRF); and three samples acid base accounting and mineralogical analysis by X-ray Diffraction

(XRD) and optical examination of polished thin sections under the microscope. The samples containing

carbonaceous materials were considered to represent the worst case in terms of potential for acid rock

drainage generation. The findings of the study are detailed under section 3.2 of the geochemistry report

(Golder Report: Geochemical Assessment, No. 1663605-316224-4).

It was concluded that the toxicological pollution potential from the waste rock material was negligible with the

possible exception of manganese. Salinity, from mainly sodium was identified as a major issue requiring

management of drainage from both waste rock and tailings storage facilities at Voorspoed. The potential for

acid rock drainage (ARD) generation was predicted to be low to unlikely due to presence of sufficient

carbonate in the waste rock for neutralising acid generated by oxidation of sulphides.

The potential for acid rock drainage (ARD) generation was predicted to be low to unlikely due to presence of

sufficient carbonate in the waste rock for neutralising acid generated by oxidation of sulphides. It was

concluded that the environmental risk associated with the waste rock material was negligible with the

possible exception of manganese. Salinity was identified as a major issue requiring management of drainage

from both waste rock and tailings storage facilities at Voorspoed.

6.2 Summary of Water Qualities Observed (near field area)

Hydrochemical analyses of the water sources, i.e. mine water, surface water and groundwater

located/monitored on the mine site area, and indicate the following:

Pit water: The water was characterised by alkaline pH (8.2-9.5) and elevated concentrations of TDS

(769-1318 mg/l), sodium (213-375 mg/L), sulphate (173-370 mg/L), nitrate as N (30-120 mg/L) and

fluoride (1.28-1.95 mg/L) that frequently exceeded DWAF (1996) domestic irrigation or livestock

guidelines between June 2013 and June 2015. The concentrations of iron and manganese rarely

exceeded domestic and irrigation water quality guidelines;

Return water Dam water: The water was characterised by near-neutral to alkaline pH (7.3-9.0) and

highly variable concentrations of TDS (196-1779 mg/L), calcium (22-102 mg/L), sodium (16-457 mg/L),

chloride (9.9-544 mg/L), nitrate (<0.057-60 mg/L) and sulphate (21-452 mg/L), which occasionally to

frequently exceeded DWAF water quality guidelines for domestic use, irrigation and livestock watering

between June 2008 and May 2016.

Groundwater: The groundwater from boreholes located close to the waste rock dump (VD BH04 and

MBH 19) was characterised by near-neutral to alkaline pH (6.8-8.7). The concentrations of TDS (236-

666 mg/L), calcium (12-73 mg/L) and sodium (51-237 mg/L) frequently to occasionally (calcium-

marginally) exceeded DWAF water quality guidelines for domestic use, irrigation or livestock watering



between April 2007 and June 2015 borehole MBH 19. The concentrations of TDS (68-574 mg/L) and

sodium (23-42 mg/L) were relatively low in borehole VD BH04 while calcium (38-82 mg/L) was relatively

high compared to MBH19 and they occasionally (TDS) to consistently (calcium) exceeded the

guidelines. The sulphate concentrations were generally low in groundwater from both VDBH04 (12-46

mg/L) and MBH 19 (19-106 mg/L).

Groundwater from borehole VD BH01, which is located close to the fines residue facilities was characterized

by near-neutral to alkaline pH (7.4-9.5), variable TDS (262-1566 mg/L), calcium (9.0-183 mg/L), sodium (58-

176 mg/L), chloride (21-620 mg/L) and sulphate (14-88 mg/L), which frequently exceeded DWAF water

quality guidelines with the exception of sulphate, which was below the guidelines. Though there were

fluctuations between monitoring events, the concentrations of TDS, sodium and chloride show a general

upward trend over time.

6.3 Conceptual Model (geochemistry)

Detailed discussion of the conceptual models during the Voorspoed operational times appears under section

3.4 of the Golder Report: Geochemical Assessment, No. 1663605-316224-4. In short it comprises of the

following components:

Open pit: where mining is currently taking place using normal drill and blast techniques.

Weathering/oxidation processes, are expected to take place on the wall rock and ore at the bottom of

the pit. The weathering products, including efflorescent salts are likely to be flushed by runoff and

seepage, which collects on the pit floor, from where it is pumped out of the pit (ref. Figure 16 above);

Waste rock dump (WRD): which is located along the pit boundary from the south to north east, and is

heterogeneous in terms of composition and particle size. Contaminants are likely to be transported to

surface water sources by runoff and to groundwater by seepage (ref to Figure 6 in Geochemical

Assessment Report referenced above).

Coarse residue dump (CRD): where wet, course treated kimberlite from the plant is dumped. The

water seeps to the toe drainof the CRD from where it is channelled to the return water dam. Some of

the water evaporates leaving behind white precipitates, which are likely to be dissolved by rainwater

and local surface water flow. Acid rock drainage processes are likely to take place in the dry residue

and contaminants are likely to reach surface water source via runoff and to groundwater through

seepage (ref to Figure 7 in Geochemical Assessment Report referenced above).

Fine residue dump (FRD), where treated kimberlite fines (sit and clay) from the plant are disposed.

The fine residue is deposited as slurry and the process water drains to the return water dam. Though

ARD processes can occur in the dry beach area (see Figure 8 in Geochemical Assessment Report

referenced above).

ROM stockpiles: located adjacent the plant. Ore is expected to be stockpiled for a short period and the

stockpiles are thus not likely to be major sources of contaminants.

In terms of groundwater inflow to the pit, it is understood to be low due to the low permeability of the

surrounding [Karoo Supergroup] Ecca Group strata consisting of mudrocks, sandstones and shale which

surrounding the kimberlite pipe (pers. comm. Voorspoed staff, 2017). The contribution of groundwater in

terms of loads are therefore insignificant in terms of the open pit contribution indicated above.



Simplified Source-Pathway-Receptor Concept.

A simplified source-pathway-receptor conceptualisation for Voorspoed is presented in Table 3.

Table 3: Conceptual source-pathway-receptor characterisation for mine facilities at Voorspoed.

Source Pathway Proximate Receptor

Ultimate Receptor

Open pit

Run-off on wall rock, ramps and pit floor to sump area.

Seepage through fractures on pit floor.

Non-perennial tributaries of the Heuningspruit and Renosterspruit. Local fractured and weathered aquifer system and contact aquifer system associated with sub-vertical faults/dolerite dykes.

The Vaal River and the regional aquifer

Waste rock dump Runoff on WRD slopes

Seepage through waste rock

ROM stockpiles Run-off

Coarse residue dump

Run-off on CRD slopes

Seepage through the coarse residue

Fine residue dump Run-off on FRD wall slopes

Seepage through fine residue

The major receptors are:

v) Surface water: The mining is taking place on a watershed. Un-named non-perennial tributaries drains

the eastern side into the Heuningspruit, and western side into the Renosterspruit. The Heuningspruit

drains into the Renosterspruit and ultimately the Vaal River. The monitoring database for raw water

dam at Voorspoed indicate that the water quality of Koppies dam, which is located on Renoster, is

alkaline with variable TDS (254-781 mg/L), sodium (42-218 mg/L), chloride (38-303 mg/L) and sulphate

(29-118 mg/L).

vi) Groundwater: Groundwater around Voorspoed occurs in shallow aquifer zone comprising the

weathered and fractured, layered Karoo Ecca Group strata, which is classified as a minor to

insignificant aquifer. Deep water bearing zone may exists, but contribute to a much lesser degree to the

flow regime. Secondary geological structures (viz. sub-vertical faults and dykes) behave as preferential

flow paths for groundwater flow (i.e. contact aquifer units). Close to the pit, groundwater flows towards

the pit and north of the residue dumps, groundwater flows in a northerly and north easterly direction

while south of the mine flow occurs in a south – south westerly flow direction.

Groundwater quality around the mine area monitoring sites are characterised by slightly elevated

salinity levels (TDS ~750 mg/L), with elevated [rising] sulphate, sodium and chloride concentrations.

Although fluoride has been identified as one of the risk constituents in the waste rock classification

study, it is confined to the pit water quality and probably represent a primary deep water source

associated with the remaining Kimberlite orebody.

6.4 Sampling and Laboratory Program

A detailed discussion of this component appears under section 4.0 of the Geochemical Assessment Report

(as referenced above), covering the following aspects:

Sampling Program; and

Laboratory Program.

The actual sampling sites, i.e. mine waste, water and seepages are illustrated in Figure 19 below.



6.5 Geochemical Test Results


(as referenced above), covering the following aspects:

Environmental Mineralogy:

The mineralogical analysis was aimed at identifying minerals that have a potential of generating acidity

(sulphides and sulphates) and neutralisation potential (including carbonate and silicate minerals).

Neutralisation capacity in the CRD, FRD and WRD materials is expected to be provided by calcite, which is a

fast-reacting (dissolving) buffering mineral. The alumino-silicate minerals are likely to provide additional

buffering capacity in the mine residue materials, albeit at variable rates as these are fast (diopside) to very

slow (microcline) weathering minerals.

Alumino-silicate minerals were rare to major phases in all the samples. Calcite, a carbonate mineral occurred

as a minor phase (2.2-7.4 wt. %) in all samples.

Secondary mineral precipitates were observed mainly on CRD surfaces and around seepage areas. The

precipitates were identified to be sulphate minerals thernardite (Na2(SO4)) and gypsum (Ca(SO4)·2H2O).

These minerals precipitate from sulphate-rich solutions, acting as temporary sinks for dissolved metals,

frequently dissolving again during rainfall events as they are highly soluble (MEND, 2009).

Elemental Composition:

The extent of elemental enrichment in the CRD, FRD and WRD samples was assessed using the

geochemical abundance index (GAI). The elements that were found to be enriched in at least one sample of

the different mine residue materials are provided in Table 4 below.

Table 4: Geochemical Abundance Index for waste rock, coarse residue and fine residue samples.

Source of Sample Material Type Sample count

Elements with GAI > 0 (Elements with GAI > 3 are highlighted in bold)

Coarse Residue Dump Coarse Residue 3 As, Au, Ba, Bi, C, Cr, Hf, La, Pt, S, Se and Te

Waste Rock Dump Waste Rock 3 As, Au, B, Bi, C, Cr, Cs, Hf, Li, Pt, S, Sb, Se, Th and Te

Fine Residue Dump Fine Residue 3 As, Au, Ba, Bi, C, Ce, Cr, Hf, La, Mg, Nd, Ni, Pt, S, Se and Te.

Enrichment of elements in mine residue samples over crustal concentrations was also determined in Figure

12 of the Geochemical Assessment Report (section 5.2, page 18) and can be summarised as follows:

The waste rock, coarse residue and fine residue materials at Voorspoed materials are enriched (in

decreasing order) in tellurium, carbon, bismuth, platinum, gold, selenium, arsenic, antimony, lanthanum,

chromium, boron, barium and sulphur.

Selenium, arsenic, antimony, chromium, boron and sulphur are environmentally-significant as they are

associated with sulphides, carbonates and mafic silicate minerals, which are fast weathering minerals.

Thus, these elements are potential constituents of concern (PCOCs) from the different residue dumps at

Voorspoed. The other enriched elements, e.g. tungsten, are mainly insoluble and therefore not

environmentally significant.

6.6 Acid Base Accounting


(as referenced above), high-lighting the following observations:

The total sulphur (0.04%-0.11%), sulphide (0.01%-0.03%) and sulphate (0.001%-0.16%) content of all

mine residue materials was very low.



Bulk neutralization potential (Bulk NP) was generally high in the waste rock (40-48 kg CaCO3 eqv t-1),

coarse residue (47-63 kg CaCO3 eqv t-1) and fine residue samples (56-74 kg CaCO3 eqv t-1). The

carbonate neutralization potential (CaNP) for all mine residue samples (23-52 kg CaCO3 eqv t-1) was

less than Bulk NP indicating that neutralization potential was provided by both carbonate and silicate

minerals;

The alkaline paste pH (9.1-10.9) indicates sufficient reactive NP in all mine residue materials to buffer

acidity generated by the initial oxidation of sulphides during the testing procedure. There is excess

buffering capacity in the coarse residue, fine residue and waste rock materials, with Bulk NP exceeding

acid potential (AP) in all samples.

Classification of acid rock drainage (ARD) potential show that all the coarse residue, fine residue and

waste rock samples are not potentially acid generating (Non-PAG).

Specific references to the applicable guidelines used for the evaluation of the Voorspoed geochemical

analyses (i.e. Bulk NP and ARD) is mentioned in section 5.3 of the Geochemical Assessment Report

[referenced above].



Figure 19: Location of mine waste, seepage and water samples



Net acid generation (NAG) pH and TNPR (viz. bulk neutralization potential /total acid producing) of all the

mine residue samples also classify all the materials as Non-PAG and illustrated in Figure 20 below.

Figure 20: Plot of NAG pH versus TNPR (Bulk NP/TAP) of coarse and fine residue and waste rock.

6.7 Drainage Chemistry Analyses


(as referenced above). Australian standard leaching procedure (ASLP) and net acid generation (NAG) leach

tests were carried out on coarse residue, fine residue and waste rock samples, in order to obtain indications

of the potential drainage quality and PCOC from the mine residue dumps at Voorspoed.

These short-term leach tests measure readily soluble components of geological materials but do not predict

long term water quality. Water-rock interactions often develop over periods of time that are much greater

than can be represented in an 18 to 24 hour extraction test.

Leachate generated by net acid generation (NAG) leach tests represents complete and instantaneous

oxidation and leaching of all reactive minerals. These tests were done to assess the maximum (worst case)

quality of drainage from the coarse residue dump, fine residue dump and waste rock dumps. Under field

conditions, sulphide oxidation and release of elements will occur gradually and concentrations in mine

drainage are expected to be lower than NAG leachate chemistry at any given time.



The results of leach tests, seepage, return water dam and pit water samples are summarized and compared

with DWAF (1996) water quality guidelines in Tables, 6 to 8 and Figures 16 to 18 of the Golder Report:

Geochemical Assessment, No. 1663605-316224-4.

The results were also compared to resource water quality objectives (RWQO) for management units in the

Renoster River catchment. It should however be noted that RWQO are set only for pH, EC, turbidity and

ammonia for catchment C70H, in which the Voorspoed mine is located.

A Piper Diagram plot of the drainage chemistry analyses results for pit water, CRD, FRD and WRD are

illustrated in Figure 21 below and high-lights the strong sodium-chloride (Na-Cl) signature of the Karoo

aquifer system in the Voorspoed area (also with reference to Figure 2 in section 5.1.2 above).

Figure 21: Piper diagram of waste rock, processed waste rock seepages and pit water samples.

With regard to the drainage chemistry analyses of the individual [potential] sources of leachate on the

Voorspoed mine site area, a detailed discussion appears under the following sections of the Geochemical

Assessment Report:

Section 5.4.1: Coarse Residue Dump Drainage –

The coarse residue materials are likely to produce predominantly near-neutral, low-metal drainage

upon exposure to rainfall, and specifically (wrt WRC et al 1996 domestic and irrigation water

quality guidelines):

pH (alkaline), aluminium, iron and manganese, and Sodium absorption ratio (SAR) for irrigation

water.



The NAG leachate results indicate that the coarse residue materials are likely to generate neutral

mine to acid rock drainage with low metal concentrations and likely to be elevated and to exceed

water guidelines for the following constituents, i.e.:

Manganese, mercury, aluminium, calcium, iron, and total dissolved solids, pH and sodium SAR).

Individual seepage samples from the CRD exceeds pH, electrical conductivity, calcium, sodium and SAR

domestic and irrigation guidelines

Fine Residue Dump Drainage –

The fine residue materials from the three facilities are likely to produce predominantly near-neutral,

low-metal drainage upon exposure to rainfall (wrt WRC et al 1996 domestic, livestock and

irrigation water quality guidelines):

pH (alkaline), aluminium, iron and manganese, and Sodium absorption ratio (SAR) for irrigation

water.

The NAG leachate results indicate that fine residue materials are likely to generate neutral mine to

acid rock drainage with low mental concentrations, i.e.:

pH (alkaline), aluminium, iron, manganese, mercury, total dissolved solids, sodium (SAR), and

calcium.

Water samples from the FRD was neutral mine drainage with low metals, however, the water sample was of

a sodium/chloride signature (see Figure 21) and it exceeded the WRC et al (1996) water quality guidelines

for pH (alkaline), total dissolved solids, nitrate, sulphate, calcium, molybdenum, chloride, sodium, SAR and

selenium.

Waste Rock Dump Drainage –

The waste rock materials are likely to produce predominantly near-neutral, low-metal drainage

upon exposure to rainfall (wrt WRC et al 1996 domestic, livestock and irrigation water quality

guidelines):

Aluminium, pH (alkaline), manganese, iron, SAR.

The NAG leachate results indicate that the waste rock materials are likely to generate neutral mine

to acid rock drainage with low mental concentrations

Manganese, mercury, total dissolved solids, pH (alkaline), sodium (SAR), aluminium, calcium

and iron.

Pit and Return Water Dam –

Sample analyses indicate neutral mine drainage with low metals, with a sodium/chloride signature

(Figure 21) and exceeded the following water quality guidelines selectively for domestic, livestock

and irrigation (WRC et al, 1996):

Total dissolved solids, nitrate, sodium, SAR, sulphate, fluoride and molybdenum.

The elevated nitrate levels could be due to explosives residue. See discussion of the elevated fluoride in

the pit water component in section 5.1.2 above.

6.8 Waste Assessment and Classification

A detailed discussion on the analyses results for the waste assessment appears under section 5.5 of the

Geochemical Assessment Report reference above. Please note that the Waste Classification and

Management Regulations (WCMR) and the Norms and Standards for the Assessment of Waste for Landfill

Disposal (GN R.634 to R636, 23 August 2013) applies herein – see section 2.4 in the Geochemical



Assessment Report referenced above. In terms of the potential sources of elevated geochemical

constituents, the following observations were made:

Course Residue Dump – (3 samples taken)

Waste Assessment:

Total concentrations of barium, copper, fluoride, manganese, nickel and vanadium exceeded the

total concentration threshold (TCT0) levels; and

The coarse residue material is not Type 4 waste as at least one parameter exceed TCT0 but it

does not meet the definition of Type 3 waste due to low risk from leachable concentrations (LC),

i.e. all parameters LC≤LCT0.

Waste Classification:

Physical hazards: classified as non-hazardous in terms of physical hazards;

Health hazards: The total concentration of aluminium, calcium, iron, magnesium, potassium and

silicon exceeded 1% in the coarse residue samples. However, none of these parameters exceed

1% in leachate and therefore do not constitute a health risk.

Carcinogens (Cd, Ni, As and Cr (VI)): The total and leachable concentrations of carcinogenic

trace metals were <0.1% in the samples from the CRD. Therefore none of these elements

constitute a health risk.

Environmental hazard: The CRD is considered to be non-hazardous to the environment due to

low solubility of elements, i.e. aluminium, calcium, iron, magnesium, potassium and silicon, and

the leachable concentrations of these elements do not exceed the % threshold for environmental

hazard.

Fine Residue Dump – (three samples taken)

Waste Assessment:

Total concentrations of barium, copper, fluoride, manganese, nickel and vanadium exceeded the

TCT0 levels, however, leachable concentrations of all potential constituents of concern were

less than LCT0 in all samples; and

The residue from FRD 1A, FRD 1B and Phase 2 FRD is not Type 4 waste as at least one

parameter exceed TCT0 but it does not meet the definition of Type 3 waste due to low risk from

leachate (all parameters LC≤LCT0).


Physical hazards: classified as non-hazardous in terms of physical hazards;


silicon exceeded 1% in the fine residue samples. However, none of these parameters exceed

1% in leachate and therefore do not constitute a health risk.

Carcinogens (Cd, Ni, As and Cr (VI)): The total and leachable concentrations of carcinogenic

trace metals were <0.1% in the samples from the FRDs. Therefore none of these elements


Environmental hazard: The leachable concentrations of aluminium, calcium, iron, magnesium,

potassium and silicon do not exceed the % threshold for environmental hazard. Therefore the

fine residue material from the FRDs is considered to be non-hazardous to the environment due

to low solubility of elements.

Waste Rock Dump – (three samples taken)



Waste Assessment:

Total concentrations of arsenic, barium, copper, fluoride, manganese, nickel and vanadium

exceeded the TCT0 levels (at least one of the three samples), however, leachable

concentrations of all analytes were less than LCT0 in all the samples; and

The waste rock material is not Type 4 waste as at least one parameter exceed TCT0 but it does

not meet the definition of Type 3 waste due to low risk from leachate (all parameters LC≤LCT0).


Physical hazards: Classified as non-hazardous in terms of physical hazards;


silicon and sodium exceeded 1% in the waste rock samples. However, none of these

parameters exceed 1% in leachate and therefore do not constitute a health risk.

Carcinogens (Cd, Ni, As and Cr (VI): The total and leachable concentrations of carcinogenic

trace metals were <0.1% in the samples from the WRD. Therefore none of these elements


Environmental hazard: The leachable concentrations of aluminium, calcium, iron, magnesium,

potassium, sodium and silicon do not exceed the % threshold for environmental hazard.

Therefore the waste rock material from the WRD is considered to be non-hazardous to the

environment due to low solubility of elements.

6.9 Conclusions (Geochemical Assessment)

Voorspoed Pit

1) According to monitoring data, the pit water is alkaline and brackish, with sodium, sulphate, nitrate and

fluoride that frequently exceeded DWAF (1996) domestic irrigation or livestock guidelines.

2) The pit water is neutral mine drainage with low metals, but exceedances of multiple parameters in the

domestic, livestock and irrigation water quality guidelines

Waste Rock Dump

3) Previous studies suggested low potential for acid rock drainage from the waste rock and low

environmental risk from seepage, except for elevated manganese.

4) The waste rock is not potentially acid generating (Non-PAG).

5) The waste rock is likely to produce predominantly near-neutral, low-metal drainage upon exposure to

rainfall, with pH likely to exceed RWQO for local catchment management unit C70H; aluminium, iron

and manganese are likely to exceed the domestic and irrigation water quality guideline and Sodium

Absorption Ratio likely to exceed the irrigation water quality guideline.

6) The sampled waste rock from the WRD is classified as non-hazardous waste.

7) Although the waste rock material might be considered as Type 3 for the purpose of cover design (in

terms of GN R. 635 Regulation 7(6)), the environmental risk associated with seepage from the dump is

similar to that of a Type 4 waste.

Coarse Residue Dump

8) The coarse residue is not potentially acid generating (Non-PAG), although secondary sulphate

precipitates were observed on CRD surfaces and around seepage areas.

9) The coarse residue materials are likely to produce predominantly near-neutral, low-metal drainage upon

exposure to rainfall, with pH likely to exceed RWQO for local catchment management unit C70H;



aluminium, iron and manganese are likely to exceed the domestic and irrigation water quality guidelines

and Sodium Absorption Ratio likely to exceed the irrigation water quality guideline.

10) The material from the CRD is classified as non-hazardous waste.

11) Although the coarse residue material might be considered as Type 3 for the purpose of cover design (in

terms of GN R. 635 Regulation 7(6)), the environmental risk associated with seepage from the dump is


Fine Residue Dump

12) The fine residue is not potentially acid generating (Non-PAG).

13) The fine residue materials are likely to produce predominantly near-neutral, low-metal drainage upon

exposure to rainfall, with pH likely to exceed RWQO for local catchment management unit C70H;

aluminium, iron and manganese are likely to exceed the domestic and irrigation water quality guidelines

and Sodium Absorption Ratio likely to exceed the irrigation water quality guideline.

14) The sampled materials from all the FRDs are classified as non-hazardous waste.

Although the fine residue material might be considered as Type 3 for the purpose of cover design (in terms

of GN R. 635 Regulation 7(6)), the environmental risk associated with seepage from the three dumps is


A detailed summary of the geochemical assessment appears under section 6.0 of the Geochemical

Assessment Report referenced above.

6.10 Appendixes Related to the Geochemical Assessment

The following appendixes were developed during the project period and are available in the relevant reports:

Golder Report No. 1663605-314859-1 (see References, Item 11.0 below):

Appendix A: Groundwater and open (surface) water LAD certificates and analytical data; and

Appendix C: Waste Chemistry LAB certificates and analytical datasets.

Golder Report No. 1663605-316224-4 (see References, Item 11.0 below):

Appendix B: Method Statement;

Appendix C: QAQC Statement;

Appendix D: Detailed Results; and

Appendix E: Laboratory Certificates (An update of Appendix C above).



7.0 FLOOD LINE ASSESSMENT

The Voorspoed mine is situated on the farm Voorspoed 401 in the Free State, 30 km from Kroonstad. The

study area is situated within the primary catchment of the Vaal River and within quaternary catchment C70H.

Locally the site is drained by tributaries of the Heuningspruit, which runs in a north-westerly direction where it

joins the Renoster River, approximately 15 km to the north.

The site is located on a high point above the headwaters of four streams that drain the area. The locations of

the perennial and non-perennial streams are shown in Figure 22. There are no identifiable water courses

draining across the site. The distance of the identified water courses from the mine boundary varies between

200m and 800m. Given the distance of the water courses from the mine boundary due to the mine being

located on the catchment divide, no flood lines need to be determined.



Figure 22: Voorspoed Mine - Perennial and Non-perennial Streams



8.0 DYNAMIC WATER AND SALT BALANCE

A detailed discussion of the Voorspoed mine site area’s dynamic water and salt balance appears in Golder

Report: Voorspoed Diamond Mine Water and Salt Balance Report 2017, No.1663605-316021-3. A summary

with specific references] is provided herein.

Site locality and description ito the Vaal River Water management Area (WMA) and local drainages

comprising of the Heuningspruit (Quaternary Catchment C70H) and the Renoster River (Quaternary

Catchment C60G), see Figure 22 above.

A description of the Model Data (section 2.0 in the Water and Salt Balance Report) is provided covering the

following aspects of the mine site area:

Climate data, mainly rainfall data from the SAWS Station 0401407 W (Middelweg) showing the

following criteria:

The mean annual precipitation (MAP) at the station is 495 mm/a;

The area is a summer rainfall area with low rainfall from May to September (below 17 mm/month);

The annual precipitation measured at the gauge varies between 265 mm/year and 1 107 mm/year;

24 Hour Storm Rainfall Depths (mm) were conducted (Table 2 under sub-section 2.2, showing that

rain storms generating a downpour of >50 mm (driving a moderate groundwater recharge event)

has a return period of 1 in ~5 years;

Average S-Class pan evaporation is 1551 mm/year measured at C6E001 station (highest average

monthly evaporation occurs in December).

8.1 Process Water Reticulation System Description

The water reticulation diagram for the Voorspoed Mine is shown in Figure 23 below (section 2.3 of the Water

and Salt Balance Report referenced above). There is a single open pit from which ore is mined and sent to

the Plant for processing. Raw water is sourced from the Koppies Dam and transferred to the Renoster

storage. It is then transferred to the Storm Water Control Dam. The Renoster storage also supplies the Raw

Water Dam (RWD) under extreme dry conditions.

There are a few sites on the mine site area where additional flow meters are required, as noted in subsection

2.7 of the Water and Salt Balance Report.

8.1.1 Water and waste storage facilities

A detailed description of the Water Related Infrastructure appears in section 2.4 of the referenced report (viz.

Water Related Infrastructure), and a summary of the Voorspoed Mine Water Storage Facilities is listed in

Table 5 below.

Table 5: Summary of the Dam Characteristics

Dam Catchment area (ha)

Capacity (m3)

Surface area at capacity (m2)

Operating procedure/level maintained

Outflow pump capacities (m3/hr)

Koppies Dam

4,2Mm3 Only release from dam when Renoster storage is below 2.5m wall height through sluice gates

Renoster Storage

200 270,000 100,000

Abstract to maintain 45-55% summer level in SWCD and 55-65% in winter. Abstract to RWD under extreme conditions (RWD below 15%)

220



Dam Catchment area (ha)

Capacity (m3)

Surface area at capacity (m2)

Operating procedure/level maintained

Outflow pump capacities (m3/hr)

RWD 14 75,000 18,000 Spills to Storm Water Control Dam (SWCD)

250

SWCD None 290,000 86,250

Maintain level:

45-55% summer

and 55-65% in winter

70



Figure 23: Voorspoed mine water reticulation system showing monthly water meter figures (viz. minimum, average and maximum).



The Waste Storage Facilities on the Voorspoed Mine are as follows:

Fine Residual Disposal: (listed in Table 1 below)

Table 6: FRDs Summary

FRD Surface area(m2)

FRD (Phase 2) 547,972

FRD 1A 22,816

FRD 1B 24,950

TOTAL 595 738

CRD Dumps: Seepage and runoff collected from CRD reports to the RWD (via trenches). No specific

measurement of this flow is available due to difficulties with flow measurements.

Open pit: An open area of ~75 ha, all runoff and groundwater ingress (insignificant volume) is pumped

to the RWD. An average volume of ~ 14 000 m3/m (~5 l/s) is pumped from the pit sump(s).

8.1.2 Water demand figures

The water demand (m3/month) is listed in Table 7 below.

Table 7: Average Water Demands

Plant Average Water Demand (m3/month)

Voorspoed plant 120,000

LDV refuel bay, stores waste yard, AECL - washwater

1,000

Sandvik workshop - washwater 200

EMV washbay - washwater 1,000

Dust suppression 15 000

TOTAL 137 200

8.2 Water Balance Modelling Methodology and Results

A detailed description of the model characteristics, climate model and model results appears in section 3.0

and 4.0 of the Water and Salt Balance Report [referenced above], includes the following model scenarios:

An average daily water balance model based on actual pumping records and rainfall data:

2015-2016 average water balance model (Figure 8 on page 14).

Forecasts based on rainfall sequences (50 different ones), followed by an statistical summary of the

results:

2017-2018 mean annual water balance model – average year (Figure 9 on page 15);

2017-2018 mean annual water balance model – wet year (> 90th percentile, Figure 10, page 16);

and

2017-2018 mean annual water balance model – dry year (<10th percentile, Figure 11, page 17).

The water management system was simulated for the period January 2014 to October 2018. Total storage

changes (i.e. the balance of Inflows – Outflows) are indicated on each model outcome and indicates a

positive water balance in all cases/scenarios simulated, i.e. between +54 m3/d (dry season), to +65 m3/d (wet

season), with a forecast average water balance of +58 m3/d on average rainfall.



8.3 Salt Balance

A detailed description of the Voorspoed mine site area’s salt balance is presented in section 5.0 of the Water

and Salt Balance Report 2017. The available Total Dissolved Solids (TDS) concentrations recorded for the

Renoster Storage and the Raw Water Dam were incorporated in the model and used during the calibration

process and includes the following model scenarios:

An average daily water balance model based on actual pumping records and rainfall data:

2015-2016 average water balance model (Figure 12 on page 19).

Forecasts based on rainfall sequences (50 different ones), followed by an statistical summary of the

results:

2017-2018 mean annual water balance model – average year (Figure 13 on page 20);

2017-2018 mean annual water balance model – wet year (> 90th percentile, Figure 14, page 21);

and

2017-2018 mean annual water balance model – dry year (<10th percentile, Figure 15, page 22).

The water management system was simulated for the period January 2014 to October 2018. Total salt load

(i.e. Input load kg/d – Output load kg/d) are indicated on each model outcome and indicates an “in-balance”

salt load varying between 1% and 3% in all cases/scenarios simulated, i.e. -46 kg/d (dry and wet season),

with forecasted -47 kg/d on average rainfall for 2017-2018. Total change in storage, i.e. what is currently

sitting in the storage facilities varies between +740 kg/d (dry season) to +979 kg/d (wet season), with an

average of +831 kg/d forecasted for 2017-2018.

The average TDS concentrations for the various water sources used in the model are presented in Table 8

These values were assumed based on available data for similar sites and/or determined during the

calibration process.

Table 8: Source terms TDS concentrations

Source Average Concentration (mg/l)

Rain 40

Koppies Dam 600

Natural Runoff 400

CRD Runoff and Seepage 1200

Plant Runoff 1000

Ore Moisture 3500

FRD Runoff 2500

Groundwater 400

Wash bay Runoff 2000

Pit Runoff 980

Wash water 200

Potable water 200

A Model User Interface has been designed for the Voorpsoed Mine and special training has been provided

[on the 11th of September 2017 at the Golder, Midrand Offices]. An explanation of the model is provided in

section 6.0 of the Golder Report: Voorspoed Diamond Mine Water and Salt Balance Report 2017,

No.1663605-316021-3).

8.4 Conclusions and Recommendations (Water & Salt Balance)

The following has significance to the water and salt balance study of the Voorspoed Mine:



Conclusions:

During the 2015/2016 Hydrological Year (which was based on the pumping records):

Approximately 3.5Ml/d, on average, is added to the system, of which almost 1.8Ml/d is sourced from

Koppies Dam;

The largest portion of water is lost from the system via interstitial storage and residual moisture in

the FRD’s and CRD (approximately 2.1Ml/d); and

The change in volume stored on site over the period is insignificant (0.1Ml/d).

Comparing the estimated volumes that need to be brought in from Koppies Dam for an average, wet

and dry year, the 2015/2016 year is comparable to a very dry year.

Due to the current management practices of Renoster Storage and the Storm Water Control Dam,

spillages are likely to occur at both facilities during a wet, average or dry year.

The differences between the water balance (i.e. inflows vs outflows, and what is stored on the mine site

area, are significantly small (~1 m3/d); and

Differences between the salt load inputs and outputs indicate slight in-balances in the order of <5%,

however, improvement of the water monitoring program would eventually minimize these differences.

Due to the nature of the primary salts contained in the rock mass, which is a characteristic of the Karoo

Ecca Group sediments, a positive salt load has been developed on the site, which is currently contained

by the management of seepages from the CRD and FRD sites and a “no discharge” condition I terms of

the water balance the mine site area.

The following observations were made during the flow meter assessments:

There are flow meters with consistent data for most of the lines on the mine.

A flow meter is not installed from the penstock to the RWD. Further to this the abstraction to the plant

from the RWD and the SWCD is not metered separately. This poses a challenge to the assessment of

the actual raw water requirements of the mine.

Water from the EMV wash bay to the plant is not metered. This may be small quantities but helpful in

the understanding of the system.

Recommendations:

Expansion of the water monitoring plan, specifically aimed at gaining confidence in the volumes of water

transferred between facilities on a daily basis and the volume of water stored on site;

Expansion of the water quality monitoring plan, to be able to more accurately model estimate future salt

loads;

Continued data capturing within the input spreadsheets of the water and salt balance model; and

As more data becomes available the calibration of the various unknown elements within the model can

be improved.

9.0 NUMERICAL GROUNDWATER FLOW AND CONTAMINANT TRANSPORT MODEL

As outlined in the objectives of the conceptual model description (see section 5.2 above), the purpose of this

numerical model approach is to;

Aid in charactering the hydrogeological related impacts associated with the Voorspoed mine; and,

To forecast the impacts of the mine post operations.



Through forecasting the post operational impacts, appropriate mitigation measures can be recommended to

limit the impact of the mine after closure. The preceding sections of this study dealt with the characterisation

the current condition of the site. While the following chapter discusses the set-up and results of a numerical

model used to forecast groundwater conditions.

A detailed discussion of the groundwater flow model and contaminant transport model appears under section

4.0 of the Hydrogeological Investigation Report, Golder Report No. 1663605-315698-2, and highlights the

following aspects of the numerical modelling part of the investigation:

Model Design, with emphasis on:

Boundary conditions, i.e. constant head, specified flux and a combination of the two;

3D Model Layering, i.e. 24 layers with specified hydraulic characteristics down to ~460 m, thus ~

150 m below the base of the pit.

The numerical modelling considered assessing mine development and the post-closure times:

Scenario 1: Steady state model: A steady state model has been developed to describe the aquifer system

under pre-mining conditions (2004 water level information).

Scenario 2: Transient model calibration – Operational period of the mine (2008 -2019). The calibration of the

model is evaluated through pit inflows, water level distributions and water quality data.

Scenario 3A: Transient simulation through the post operational period to quantify pit flooding and mass

transport without the implementation of mitigation measures.

A detailed description of the numerical modelling scenarios appears under section 4.3 of the above-

mentioned report. Scenario 2 (viz. the transient model) simulates the pit inflows over the period January

2008 up to January 2017 (as illustrated in Figure 24 below)

Figure 24: Inflows to the Voorspoed Mine pit simulated between 2008 and 2017.

Qualitatively, the model is deemed to suitably represent inflows to the pit. The resulting cone of depression,

representative of current conditions, extends 1.2 km west of the pit and is limited to the east due to seepage

from the waste rock dump.



The simulated hydraulic head distribution representing current conditions was evaluated against the

measured data collected during the 2017 hydrocensus and illustrated for [water level] monitoring site VD-

BH4 in Figure 25 below, see position in Figure 1. Monitoring site VD-BH4 is situated directly east of the pit

and waste rock dump.

The 2017 hydraulic head distribution for the Voorspoed Mine’s “catchment area” is illustrated in Figure 26

below and portrays the following characteristics:

Groundwater, regionally reports to the Renoster and Heuningspruit surface water drainages over a

head gradient of ~61 m;

A local “dewatering cone” has developed around the pit area and is illustrated in Figure 27 below.

Figure 25: Time series water level data and simulated water level at monitoring site VDH04 (wrongly numbered VBH04)



Figure 26: Operational hydraulic head distribution (as per 2017 prediction)



Figure 27: Simulated drawdown and cone of depression of the Voorspoed Mine site area (as per 2017 hydrocensus processing)



Post operational impacts (i.e. initiated by the mine closure phase) has been modelled accordingly to the low

permeability of the country rock. Consequently, the key issues envisioned for the post operational period is

the further development of the contaminant plumes associated with CRD, FRD and WRD and secondly the

pit lake re-filling rate and water quality. This aspect is discussed under subsection 4.3.3 of the

Hydrogeological Investigation Report (Scenario 3: Post operational impacts). Of significant importance is the

Pit Lake development.

The pit void was simulated by applying (i) a high hydraulic conductivity to the pit area and correspondingly a

storativity equal to one – water ingress of ~10 l/s, (ii) direct rainfall contribution over the entire pit catchment

footprint – 631238 m2, (iii) and potential evaporation distributed over the year – 1 550 mm. No storm water

inflow was accounted for. The cumulative inflows and corresponding pit water levels are depicted in Figure

28.

The following deductions of this modelling scenario is made (the storage curve of the Voorspoed pit is

described in section 2.5 of the Hydrogeological Investigation Report [referenced above]:

After 10 years from mine closure the Pit Lake water level elevation would be at ~1240 mamsl or 170

meters below surface.

After 200 years the inflows were balanced by evaporation and thus the quasi steady state head is

expected to be at approximately 1367 mamsl (43 m below surface).

In an additional scenario, where the groundwater inflow was assumed to be approximately 4 l/s,

comparable to the operational inflows simulated, the final head elevation within the pit is expected to

be1334 mamsl (76 meters below surface).

Figure 28: Prediction of the Voorspoed Pit Lake development after closure.

The rewatering progression of the Voorspoed Pit Lake is schematically presented in F….. below, and high-

lights the fact that total rewatering will probably never materialises of the inflow to the pit is not enhance by

one or other engineered design, i.e. design of a local Pit Lake catchment system to divert as much of the

local surface runoff to the pit.



Figure 29: Schematic of the Voorspoed Mine post operational pit lake development

The main focus of Voorspoed post closure phase would be around the impact on the water quality status of

the mine site area and what quality the Pit Lake will have towards the end of the pit rewatering – which

seems to be an extremely long period, unless the runoff component is significantly enhanced which will also

have an effect on the water quality for example if the runoff is generated for example over the waste rock

dump. Water level, or aquifer saturation levels, on the other hand, has only been impacted around the pit,

and will therefore not be a significant factor for a post closure management measure.

The final water quality characteristics of the Pit Lake water body is much more relevant in terms of water

resources impacts. A detailed discussion of the Post Closure Hydrochemistry appears in subsection 4.3.3.2

of the Hydrogeological Investigation Report. The following aspects are relevant:

Plumes associated with the WRD, FRD and CRD:



captured by the pit;


consequently a component of seepage is expected to migrate downgradient toward receiving

downstream boreholes downstream the mine site area, mainly boreholes BH30 and BH4;

It was found that the sulphate plume which will migrate onto adjacent farms are unlikely to exceed

the SANS 241: 2011 drinking water limits for sulphate (250 mg/l) and similarly the livestock water

quality limit is not exceeded.

Of the receptor boreholes identified through the 2017 hydrocensus, only BH30 and BH4 (viz. both in the

far field area respectively south and east of the mine site area) are expected to be impacted. BH 30 is

expected to be impacted 10 -15 years post operations while BH4 is expected to be impacted 100 years



following cessation of mining. Thus while the sulphate concentrations in these boreholes will gradually

increase through time it is not expected that the sulphate will exceed drinking water quality.

Surface water resource (receptor):

In addition to the boreholes mentioned above, the unnamed non-perennial tributary (C70H) of the

Heuningspruit) east of the mine is expected to be a sink to the solute plume over time;

As the stream is only perennial it is likely that salt loads will accumulate during the dry periods and

be flushed down stream following rainfall events. Thus while, the groundwater concentrations are

expected to remain below drinking water levels there may be periodic spikes in surface water

quality as a consequence of discharge to the stream.

As sequence of simulated plumes between 5 and 200 years is illustrated in Figure 30 and Figure 31 below.

Pit Lake Chemistry

The chemical composition of pit water as the pit fills up will depend on a number of factors including:

Chemical composition of wall rock and associated geochemical reactions,

Surface area of exposed wall rock;

Quantity and rate of release of solutes through flushing of the wall rock;

Amount of direct rain falling into the pit and evaporation rates;

Groundwater inflow rates; and

Mixing or stratification of the pit water overtime

The static tests on waste rock materials indicated that rock materials in the open pit are likely to generate

near neutral drainage with high total dissolved solids, moderate sulphate and low concentration of trace

elements upon exposure to rainfall.

The drainage from the wall rock is likely to be similar to that of waste rock leachate in the long term, but the

concentrations will rise and fall with inflows and evaporation. Schematic presentations of these conditions

are shown in Figure 16 and Figure 18 above.

A postulation of the minimum and maximum Pit Lake water qualities are illustrated in Table 9.

Table 9: Pit lake water quality range based on static test data

Parameter Units Minimum Maximum

pH s.u 6.1 9.6

Total dissolved solids mg/l 173 1690

Electrical conductivity mS/m 24 221

Sulphate mg/l 30.3 456

Chloride mg/l 1.7 42

Nitrate mg/l 2.6 218

Nitrite mg/l 0.23 0.50

Fluoride mg/l 0.23 1.3

M Alkalinity mg/l 65 293

Aluminium mg/l 3.6 7.9

Arsenic mg/l 0.01 0.06

Barium mg/l 0.03 0.80



Parameter Units Minimum Maximum

Boron mg/l 0.14 0.28

Cadmium mg/l <0.00036 <0.00036

Calcium mg/l 4.7 181

Chromium mg/l 0.021 0.2

Cobalt mg/l 0.002 0.02

Copper mg/l 0.013 0.09

Iron mg/l 3.1 5.2

Lead mg/l 0.0024 0.0081

Magnesium mg/l 1.2 29.4

Manganese mg/l 0.0030 1.2

Mercury mg/l 0.0001 0.2

Molybdenum mg/l 0.0054 0.2

Nickel mg/l 0.0052 0.2

Potassium mg/l 4.0 57

Selenium mg/l 0.0049 0.047

Silicon mg/l 7.2 217

Sodium mg/l 36 360

Uranium mg/l 0.0011 0.0051

Zinc mg/l 0.023 0.67

In terms of the identified hydrochemical constituents of concern (as picked during the water study), fluoride

and sulphate concentrations becomes elevated. Other constituents such as nitrate (NO3) and a few trace

metals becomes elevated to levels above the drinking water limits for domestic water uses. As indicated

throughout the study, these elevated concentrations will be limited to the Voorspoed mine site area under

normal climate conditions.



Figure 30: Simulated sulphate (SO4) plume development from post closure phase – after 5, 10, 15 and 30 years.



Figure 31: Simulated sulphate (SO4) plume development from post closure phase – after 50, 100, 150 and 200 years



9.1 Applicable Conclusions (Numerical Modelling)

The following conclusions were drawn from the numerical modelling exercise:

Pit Lake development

The pit lake is expected to initially rebound quickly, the simulated water level within the pit after 10

years is expected to be approximately 1238 mamsl or 172 meters below surface.

After 200 years the inflows are expected to be balanced by evaporation and thus the quasi steady state

head is expected to be at approximately 1367 mamsl (43 m below surface).

In an additional scenario, where the groundwater inflow was assumed to be approximately 4 l/s,

comparable to the operational inflows simulated, the final head elevation within the pit is expected to

be1334 mamsl (76 meters below surface).

Thus it is not expected that the pit will decant and rather the pit will continue to act as local sink for

groundwater indefinitely.

Post operational contaminant transport

Sulphate was selected as there are no other sources of sulphate proximal to the mine with the

exception of the dumps and hence sulphate is a suitable tracer of mine seepage.

The contamination from WRD appears to be rainfall driven and hence the behaviour of the plume varies

seasonally.

However, the simulated plume for a period of 200 years indicates that the plume generated from the

waste rock facilities will unlikely exceed the drinking water limits in terms of sulphate on the farms

neighbouring the mine.

The CRD, while having the highest source concentrations, do not appear to impact on nearby

boreholes. It follows that either seepage from this site is not entering the groundwater system or the

boreholes installed do not suitably represent the upper fractured aquifer.

Seepage from the FRD is envisioned in part to migrate toward the pit and off site in a north easterly

direction toward identified receptors.

Similarly, the two receptor boreholes which are likely to be impacted over time, BH30 (15 years post

operations) and BH 4 (100 years post operations) are expected to gradually increase in sulphate

concentration but are not expected to exceed drinking water limits for sulphate.

Plumes associated with the WRD, FRD and CRD



captured by the pit.


consequently a component of seepage is expected to migrate downgradient toward the identified

receiving boreholes.

It was found that the sulphate plumes which will migrate onto adjacent farms are unlikely to exceed the

SANS 241: 2011 drinking water limits for sulphate (250 mg/l) and similarly the livestock water quality

limit is not exceeded.

Impact on local surface water systems

In addition to the boreholes identified, the unnamed non-perennial tributary north of the mine is

expected to be a sink to the solute plume over time.

As the stream is only perennial it is likely that salt loads will accumulate during the dry periods and be

flushed down stream following rainfall events. Thus while, the groundwater concentrations are expected



to remain below drinking water levels there may be periodic spikes in surface water quality as a

consequence of discharge to the stream.

10.0 SYNOPSIS

Golder Associates Africa (Pty) Ltd were appointed to undertake a hydrogeological investigation to guide the

closure process of the De Beers Voorspoed mine. The following synopsis was drawn from this study.

During the mining operations since 2008, a diamond pipe has been mined down to a depth of ~307 m. The

host rock formation are sediments of the Ecca Group of the Karoo Supergroup consisting mainly of

mudrocks and interbedded sandstone/siltstone horizons. Secondary geological features, such as faults,

dolerite sills and dykes are present on the mine site area. During mining operations very little groundwater

ingress occurred, and a large portion of the water requirements were obtained from external sources

(surface water supplies – nearby Koppies Dam) supplemented by a few local water supply boreholes on the

mine site area.

The hydraulic characteristics of the host rock formations are indeed low to insignificant, although all

boreholes in the near (mine site) and far (surrounding land) areas have intercepted groundwater at various

depths – highest yields, however, are associated with the sub-vertical dolerite dyke features, i.e. so-called

dolerite contact aquifer systems. The groundwater flow pattern is directed towards the surrounding surface

water drainage systems of which only the Heuningspruit and Renoster River are regarded as perennial

systems. No drainage runs directly through the mine site area, although a small tributary of the

Heuningspruit starts just of the north-eastern boundary of the mine site area.

As a result of the mine workings on the Voorspoed site, four prominent storage facilities have developed

over the time, being (i) the large waste rock dump southeast of pit area (not part of the mine water cycle), the

fine residue dumps consisting of three units and containing the final wash waste from the processing plant,

(iii) the course residue dump, containing the waste portion from the milling/processing plants, (iv) the raw

water dam which includes the captured discharges from the fine and course residue dumps, and (iv) the

storm water control dam.

In terms of the water balance status of the Voorspoed Mine, external water from the Koppies Dam and a few

boreholes in the mine site area provides the water supply to the Voorspoed operations – which is in balance

with the use as no water is discharged from the mine site area. Management practices at the main storage

facilities on site, i.e. the Renoster Storage and the storm water control dam (SWCR), spillages are likely to

develop during wet, average or dry years. The salt balance, however, indicates a steady increased based on

the primary salt loads of the rock mass on the mine site area. Seepages from the CRD and FRD are

managed and a management protocol of “no discharge to the environment” retains the salt load on the mine

site area. Groundwater quality monitoring in the far field area, i.e. land surrounding the mine site area, does

not indicate any specific increase in the normal slat loads found in the Karoo Ecca Group groundwater

systems. Monitoring of the far field surface water runoff is ominously important – especially downstream of

the storm and return water storage facilities.

The geochemical assessment of the mine site area included all the waste rock dumps (i.e. Karoo Ecca

Group sediments, basalt and dolerite rock), and processed Kimberlite ore (i.e. CRD and FRD dump sites), as

well as the water (i.e. seepages from processed rock dump sites), pit water and storage facilities (i.e. storm

water and return water dams). The geochemical assessment focussed on the (i) acid producing

characteristics, (ii) geochemical constituents of the seepages, and (iii) the leachates of the waste and

processed rock dump sites. The geochemical results indicate (i) not potentially acid generating, (ii) these

sites, upon exposure to rainfall produce a predominantly near-neutral, low-metal drainage with pH likely to

exceed the recommended water quality objectives the C70H quaternary catchment [with regard to pH, EC,

turbidity and ammonia], and (iv) concentrations of aluminium, iron and manganese are likely to exceed the

domestic and irrigation water quality guidelines and (v) Sodium Absorption Ratio likely to exceed the

irrigation water quality guideline. Additionally, the sampled waster rock, and material from the CRD and FRD

are classified as non-hazardous waste. To conclude, although the fine residue material (FRD) might be

considered as Type 3 for the purpose of cover design (in terms of GN R. 635 Regulation 7(6)), the

environmental risk associated with seepage from the three dumps is similar to that of a Type 4 waste,



however, coarse residue material (CRD), fine residue material (FRD), and waste rock material (WRD) are

considered to be non-hazardous to the environment due to low solubility of elements in crystallised state.

In terms of the groundwater chemical characteristics in the far field area, it is characterised by slightly

elevated salinity levels (TDS ~750 mg/L), sodium, chloride and sulphate concentrations – which abides it’s

salinity (viz. Na-Cl) origin from the ambient Karoo Ecca Group water quality type, and the sulphate probably

from concentrations of primary iron-pyrite in the sandstone layers imbedded in the Ecca Group. Under field

conditions, sulphide oxidation and release of elements will occur gradually and concentrations in mine

drainage are expected to be lower than NAG leachate chemistry at any given time.

In terms of the flood line analyses, the conclusion is that the Voorspoed Mine is situated on the highest

elevation of the C70H quaternary catchment – above the headwaters of this quaternary catchment, as well

as the neighbouring catchments that drains the area. There are no identifiable surface water drainages

across the site.

Finally, the numerical modelling based on a 3D finite element model covers (i) the steady state model (i.e.

describe the aquifer system under pre-mining conditions (2004 conditions), (ii) a transient model calibration

(i.e. operational period 2008-2019), a transient simulation through the post-operational period to quantify pit

flooding and mass transport (excluding mitigation measures). A 3D finite element model, consisting of a 24

layered package (i.e. 460 m), covering the total depth of the Voorspoed pit (~307 m), including three dolerite

sill contact water bearings zones, as well as including the major sub-vertical dolerite dyke and fault line

contact aquifers.

A detailed conceptual model was constructed for the Voorspoed Mine site area based on the regional

geology and the detail geological model of the mine site area. The concept model depicts the dewatering

that took place during the Life of Mine, however, based on the hydrogeological study [and the insignificant

overall hydraulic nature on the surrounding geological formations], impacts such as dewatering and

migration of potential contaminants from the mine site area based on the elevation model, does not progress

significantly into the far field area.

The Steady State numerical model indicates the natural catchment-like groundwater flow regime describes

the status of the aquifer system(s) as depicted in the conceptual model, and recharged water ultimately

reports to the major surface water drainages after a momentous long flow period [due to the low hydraulic

nature of the aquifer systems. Impacts are therefore mainly localised, with a steady recovery supported by

local/direct rainwater recharge and “re-freshing” of the aquifer system.

The Transient Model Calibration (i.e. pit inflows and surrounding water table elevation), indicates (i) the

dewatering cone extends 1.2 km west of the pit and is limited to the east due to seepage from the waste rock

dump, and (ii) impacts (direct infiltration into the upper shallow aquifer system from the coarse residual dump

are deemed valid.

The Post Operational Impacts highlights (i) the Pit Lake development, which indicate that evaporation from

the pit sidewalls and the pit lake will result in a slow recovery rate and after 200 years, the inflows (high

inflow scenario) are balanced by evaporation and thus the quasi steady state head is expected to be at

approximately 1367 mamsl (43 m below surface). It is therefore concluded, that based on the actual inflow

volumes (excluding any engineered, local Pit Lake Catchment design), the final water table elevation will be

between 76 m (4 l/s inflow, + rainfall - evaporation), and 43 m (~10 l/s inflow, + rainfall – evaporation).

Secondly, (ii) the post closure hydrochemistry (Mass Transport Model) based on the calibrated transient

model, was utilised to simulate the post-operational plume migration from the WRD, CRD and

FRD – sulphate was used as the tracer for contamination migration as it was found to be associated with the

waste rock facilities [and not commonly associated with agricultural practices].

The most important results of the mass transport modelling indicate, that (i) the pit will remain as a sink (i.e.

capturing local seepages via the shallow aquifer system) during post operational times due to the effects of

evaporation, (ii) due to the low permeability of the aquifer rock, the current radius of influence of the pit [sink]

is limited and a component of the seepage is expected to migrate downgradient to receiving boreholes

(BH30 and BH04) will be impacted over ~12 and 100 years respectively. In a scenario where the sulphate



plume migrates to the far field area, the mass transport model predicts that the concentration will unlikely

exceeds the drinking water limits for sulphate (~250 mg/l) and livestock.

Water quality impacts via the surface water flow system has been identified in the drainage path of an

unnamed, non-perennial tributary in the C70H quaternary catchment, just east of the storm water and return

water dam sites due to the accumulation of salt loads during dry periods, and periodic surface flooding will

flush these salt further downstream and may impact on water resources further downstream. This is

conclusion is merely a “desktop observation”, however, and it is recommended that a more detailed

investigation is considered.

The geochemistry evolution of the Pit Lake during rewatering will depend on a number of factors, including (i)

the (geo)chemical composition of the pit-wall rock formations, (ii) the surface area of the exposed rock face,

(iii) the rate at which solutes are released through pit-wall rock flushing, and (iv) the combined effects of

rainwater filling, evaporation rate, groundwater inflow rates/quality, geochemical reactions,

mixing/stratification of the water body in the pit lake – over time.

Static tests on the waste rock materials indicated that rock materials in the open pit are likely to generate

near neutral drainage with (i) high total dissolved solids, (ii) moderate sulphate and (iii) low concentration of

trace elements upon exposure to rainfall. The drainage from the wall rock is likely to be similar to that of

waste rock leachate in the long term, but the concentrations will rise and fall with inflows and evaporation.

Should an engineered, local Pit Lake catchment developed, the final impact could be significantly different.

Further investigations on refined the Pit Lake water quality signatures would require a detailed geochemical

assessment of the pit wall rock face, an aspect not catered in this study.

To conclude, recommendations related to the post-closure phase of the Voorspoed Mine are as follows:

Upgrading of the current water resources monitoring infrastructure (dedicated deep/shallow boreholes

and water meters on pipeline systems), and especially the unnamed non-perennial surface water

drainage east of the SWD and RWD area;

Active practice of the water balance modelling procedure (i.e. GoldSim modelling) and database

maintenance (incl. an updated groundwater component database system, i.e. MS Office – Excel

system);

Establishment of a local weather station on the site; and

Prediction of the long-term evolution of pit lake water chemistry based upon the volume and chemistry

based on the existing water make model of a Pit Lake (natural inflow and side wall leaching and runoff.

In addition, if a larger surface water runoff catchment is engineered in the near filed area to enhance the

pit lake water level recovery, specific aspects such as evaporative mass balance and a long-term

mixing model will have to be addressed.

11.0 REFERENCES

The following Golder reports (viz, study component reports) were consulted in prepare this Summary Report.

Several references to these are made and it is recommended that this Summary Report should be used in

conjunction with the study components reports as detailed references, they are as follows:

1663605-314859-1: Surface and Groundwater Study for Mine Closure Requirements – Enquiry No: VS-

E-085-6, i.e. Progress Report covering the (i) the hydrocensus survey and (ii) water and geochemical

results. Introduction of the water and salt balance program was included;

1663605-315698-2: Hydrogeological Investigation, i.e. addressed the (i) hydrological data assessment,

(ii) preliminary geochemical assessment, and (iii) introduction to the numerical modelling task;

1663605-316021-3: Voorspoed Diamond Mine Water and Salt Balance Report 2017, i.e. addressing the

(i) hydrological aspects of the site area, (ii) complete water and salt balances, and (iii) the GoldSim

modelling process, presented as a training course to Voorspoed staff on the 11th of September 2017;



1663605 Mem_008: A Technical Memorandum, i.e. Voorspoed Mine Floodline Assessment;

1663605-316224-4: Geochemical Assessment Report, i.e. a comprehensive update of the preliminary

geochemical assessment, including (i) information review, (ii) sampling and laboratory programme, and

(iii) geochemical test results.

Where applicable, references to several Appendixes are made which are included in the above-mentioned

reports. All these reports, and associated datasets were uploaded to the Anglo American Dropbox facility

during September and October 2017. A total of 181 files have been uploaded which includes 14 report files

and dotPPTX presentations.

Talita Germishuyse Eddie van Wyk

Senior Modeller Senior Hydrogeologist

TG/EvW/ck

Reg. No. 2002/007104/07

Directors: RGM Heath, MQ Mokulubete, SC Naidoo, GYW Ngoma

Golder, Golder Associates and the GA globe design are trademarks of Golder Associates Corporation.

g:\projects\1663605 - debeers gwss voorspoed\6.1 deliverables\g_summary_report\1663605-316475-5_vspmc_sumrep_final_301017.docx


October 2017 Report No. 1663605-316475-5

APPENDIX A Document Limitations


October 2017 Report No. 1663605-316475-5

DOCUMENT LIMITATIONS

This Document has been provided by Golder Associates Africa Pty Ltd (“Golder”) subject to the following

limitations:

vii) This Document has been prepared for the particular purpose outlined in Golder’s proposal and no

responsibility is accepted for the use of this Document, in whole or in part, in other contexts or for any

other purpose.

viii) The scope and the period of Golder’s Services are as described in Golder’s proposal, and are subject to

restrictions and limitations. Golder did not perform a complete assessment of all possible conditions or

circumstances that may exist at the site referenced in the Document. If a service is not expressly

indicated, do not assume it has been provided. If a matter is not addressed, do not assume that any

determination has been made by Golder in regards to it.

ix) Conditions may exist which were undetectable given the limited nature of the enquiry Golder was

retained to undertake with respect to the site. Variations in conditions may occur between investigatory

locations, and there may be special conditions pertaining to the site which have not been revealed by

the investigation and which have not therefore been taken into account in the Document. Accordingly,

additional studies and actions may be required.

x) In addition, it is recognised that the passage of time affects the information and assessment provided in

this Document. Golder’s opinions are based upon information that existed at the time of the production

of the Document. It is understood that the Services provided allowed Golder to form no more than an

opinion of the actual conditions of the site at the time the site was visited and cannot be used to assess

the effect of any subsequent changes in the quality of the site, or its surroundings, or any laws or

regulations.

xi) Any assessments made in this Document are based on the conditions indicated from published sources

and the investigation described. No warranty is included, either express or implied, that the actual

conditions will conform exactly to the assessments contained in this Document.

xii) Where data supplied by the client or other external sources, including previous site investigation data,

have been used, it has been assumed that the information is correct unless otherwise stated. No

responsibility is accepted by Golder for incomplete or inaccurate data supplied by others.

xiii) The Client acknowledges that Golder may have retained sub-consultants affiliated with Golder to

provide Services for the benefit of Golder. Golder will be fully responsible to the Client for the Services

and work done by all of its sub-consultants and subcontractors. The Client agrees that it will only assert

claims against and seek to recover losses, damages or other liabilities from Golder and not Golder’s

affiliated companies. To the maximum extent allowed by law, the Client acknowledges and agrees it will

not have any legal recourse, and waives any expense, loss, claim, demand, or cause of action, against

Golder’s affiliated companies, and their employees, officers and directors.

xiv) This Document is provided for sole use by the Client and is confidential to it and its professional

advisers. No responsibility whatsoever for the contents of this Document will be accepted to any person

other than the Client. Any use which a third party makes of this Document, or any reliance on or

decisions to be made based on it, is the responsibility of such third parties. Golder accepts no

responsibility for damages, if any, suffered by any third party as a result of decisions made or actions

based on this Document.

GOLDER ASSOCIATES AFRICA (PTY) LTD

Golder Associates Africa (Pty) Ltd.

P.O. Box 6001

Halfway House, 1685

Building 1, Maxwell Office Park

Magwa Crescent West

Waterfall City

Midrand, 1685

South Africa

T: [+27] (11) 254 4800

Caption Text

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