HOEKPLAATS Dolomite (Pty) Ltd Preliminary … Dolomite (Pty) Ltd Preliminary Groundwater Assessment: Portion 23 (A Portion of Portion 15) of the farm Hoekplaats 384 JR DATE: October

HOEKPLAATS Dolomite (Pty) Ltd

Preliminary Groundwater Assessment:Portion 23 (A Portion of Portion 15) of the

farm Hoekplaats 384 JR

DATE: October 2010REVISION FinalREFERENCE: 215_HoekplaatsCOMPILED FOR: Umhlaba Environmental Consulting CC

PO Box 731504Fairland2030

COMPILED BY: GROUNDWATER SQUAREConsulting Groundwater Specialists

HOEKPLAATS Dolomite (Pty) Ltd – Preliminary Groundwater Assessment:Portion 23 (a Portion of Portion 15) of the farm Hoekplaats 384 JR Ref:215_Hoekplaats (Oct’10)

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Executive Summary

Umhlaba Environmental Consulting CC contracted Groundwater Square on behalf of HoekplaatsDolomite (Pty) Ltd to compile a preliminary hydrogeological desk study investigation to provideguidance on any future groundwater studies that may be required.

The proposed opencast dolomite mine is on situated Portion 23 (a portion of Portion 15) of the FarmHoekplaats 384 JR approximately 15km south-west of Pretoria. Mining will entail a conventionaldrilling and blasting opencast operation. The targeted mining area will be approximately 300m x 500min size and approximately 40m deep.

The following main conclusions were reached:

The regional dolomitic aquifers was highlighted as a significant source of drinking- and irrigationwater;

Locally the direction of groundwater movement from the site is in a north-westerly directiontowards the Hennops River and the Aalwynkop Spring. The northern regions of the quarry floor isexpected to be at lower elevations than the Aalwynkop Spring;

The depth of mining will be ±30m below the natural groundwater level. Groundwater will have tobe pumped from the pit;

The Zwartkop dyke may potentially compartmentalise the aquifers (depending on its weatheringdepth) to restrict the extent of the groundwater dewatering cone around mining;

It is anticipated that the aquifer within the proposed mining area may be low yielding due to beingchert-poor and with limited leaching of the dolomites (to the depth of mining);

Borehole EUB-6 is situated on Ptn.23 of the farm Hoekplaats 384 JR. Six external user’sboreholes were indentified within a 1km radius of the property. The reported total daily abstractionrecorded within a 1km of Portion 23 totals approximately 38m

3/d.

Once the mine intersects the natural groundwater table, groundwater will be pumped from the pit,resulting in a cone of dewatering developing around the pit. Although the extent of dewatering may belimited/restricted due to various factors, the potential impact on external users’ boreholes and impacton base-flow to the Hennops River and Aalwynkop Spring requires further investigation.

The main recommendations for further work therefore focussed on the utilisation of a numericalgroundwater flow model to determine/evaluate the potential impacts on external users’ borehole yieldsand groundwater base-flow toward the Hennops River and the Aalwynkop Spring. Dedicatedhydrogeological boreholes should be drilled and pump tested to determine hydraulic aquiferparameters, for inclusion in the numerical model.


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Table of Contents

Executive Summary ...............................................................................................................................iiTable of Contents .................................................................................................................................. iii

1. INTRODUCTION ............................................................................................................................ 41.1. Background.................................................................................................................................. 41.2. Mining Information ....................................................................................................................... 42. TERMS OF REFERENCE .............................................................................................................. 43. SETTING ........................................................................................................................................ 53.1. Regional Setting .......................................................................................................................... 53.2. Rainfall......................................................................................................................................... 63.3. Land-use...................................................................................................................................... 63.4. Morphology and Drainage ........................................................................................................... 73.5. Soils ............................................................................................................................................. 73.6. Local Setting ................................................................................................................................ 74. GEOLOGY...................................................................................................................................... 94.1. Regional Geology ........................................................................................................................ 94.2. Local Geology............................................................................................................................ 105. HYDROGEOLOGY....................................................................................................................... 115.1. Regional Hydrogeology ............................................................................................................. 115.2. Local Geohydrology................................................................................................................... 135.2.1. Groundwater Use .................................................................................................................. 135.2.2. Hydrocensus.......................................................................................................................... 135.2.3. Depth to Groundwater Level and Hydrostatic Fluctuations.................................................. 145.2.4. Groundwater Flow Direction .................................................................................................. 165.2.5. Aquifer Yielding Potential ...................................................................................................... 165.2.6. Groundwater Quality.............................................................................................................. 165.2.7. Surface Water Quality ........................................................................................................... 186. POTENTIAL IMPACTS................................................................................................................. 206.1. Identification of Potential Impacts.............................................................................................. 216.2. Discussion of Potential Impacts................................................................................................. 217. RECOMMENDATIONS ................................................................................................................ 22

References ........................................................................................................................................... 23


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1. INTRODUCTION

1.1. BackgroundUmhlaba Environmental Consulting CC recently compiled an Environmental Scoping Report forHOEKPLAATS Dolomite (Pty) Ltd. The proposed opencast dolomite mine is situated on Portion 23(a portion of Portion 15) of the Farm Hoekplaats 384 JR approximately 15km south-west of Pretoria.

Umhlaba approached Groundwater Square undertake a preliminary hydrogeological investigation. Itwas decided to perform a desk study, which could provide guidance (and serves as the basis) for anyfuture groundwater studies that might be required.

1.2. Mining InformationThe targeted mining area will be approximately 300m x 500m in extent with a maximum projecteddepth of ±40m. The proposed mining will entail a conventional drilling and blasting opencast operationwith the frequency of blasting being dependant on product demand. Rock will be crushed andscreened to include the following products:

19mm concrete stone; 13.2mm concrete stone; 9.5mm concrete stone; ≤6.7mm super-sand.

The installation of services will include the construction of the following: Plant; Settlement dam; Workshops and fuel facilities; Administration offices; Demarcation of the salvage yard; Connection to the water and electricity supply; Sanitation facilities.

2. TERMS OF REFERENCEBased on the project objectives, the following Terms of Reference were proposed by GroundwaterSquare on 07/08/2010:

Collate and perform desktop exercise of available geological and hydrogeological maps/reportspertaining to the study area;

Compile a hydrogeological interpretation of the expected groundwater system; Identify likely impacts in view of the Dolomite Mine design and geological drilling (no impact

assessment was required); Describe dolomite compartments and decant elevations from these compartments; Based on the outcome of the desktop exercise, determine whether a full-scale investigation will

be required (and the nature thereof).

A site visit was undertaken on 15/09/2010, followed by a survey of external users to confirm certainaspects of the desktop assessment. A sample of the nearest borehole was collected to analyse thewater quality.

Disclaimer – The state of hydrogeological knowledge was presented as accurately as possible usingavailable information. Groundwater Square exercised due care and diligence in gathering andevaluating relevant information. Groundwater Square will not accept any liability in the event ofencountering unexpected aquifer conditions during mining and further investigations. Anyunauthorized dissemination or reuse of the desktop study report will be at the user's sole risk and withthe condition that Groundwater Square will not accept any liability for any and all claims for losses ordamages and expenses arising out of or resulting from such unauthorized disclosure or reuse.


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3. SETTINGPortion 23 of the Farm Hoekplaats 384 JR is located within the jurisdiction of the Tshwane MetroCouncil.

3.1. Regional SettingThe subject area as shown in Figure 3.1 falls within quaternary catchment area A21B of the UpperCrocodile sub-area of the Crocodile (West) and Marico Water Management Area (WMA). Thefollowing key groundwater issues pertain to this part of the WMA:

The southern dolomite outcrop, (parts of catchments A21A, B, D, F, G, H) is a hemisphericaloutcrop of dolomite to the east, north and west of the granite underlying Johannesburg;

The dolomite forms mostly level/flat ground to the east and northeast of Johannesburg withextensive dry land agriculture and some irrigation, especially around Bapsfontein where a total ofapproximately 12km

2is irrigated (2004 estimate);

Maximum borehole yields exceed 40L/s (as deep as 250m). Average borehole yields vary from2L/s to 10L/s. Water tables vary from <10m in vlei areas to >50m;

During 1995 the groundwater use was estimated at 21.9Mm3, mostly for the purpose of

abstraction for urban water supply (Centurion) and irrigation (Bapsfontein and Tarlton); The dolomite represents an important aquifer with significant groundwater resources, hence the

widespread abstraction. The potential for additional exploitation of the groundwater resourceswithin the catchment may be considerable;

The aquifer contributes base flow to surface drainage, which flows into the Hartbeespoort Dam; Groundwater quality is generally good. However, the dolomites are vulnerable to pollution,

especially where karst conditions are present. Groundwater protection forms an integral part ofcatchment management in dolomite areas.

Figure 3.1 Regional setting

The following key water issues were identified for this WMA:

The water requirements of the area are increasing due to the spread of settlements and irrigationdemands, especially in catchments A21A (20km to the east) and A21D (30km southwest).Available information indicates that groundwater resources are approximately 85% utilised, while


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surface water is fully accounted for; Dolomite aquifers/compartments do not coincide with surface catchment boundaries and transect

into the Upper Vaal and Olifants WMAs; Groundwater abstraction from dolomite aquifers may cause the development of sinkholes. Areas

where the ground is already unstable and water levels are allowed to fluctuate regularly, areparticularly vulnerable to sinkhole development;

Several examples exist where sewage effluent is discharged into the surface drainage systemswhich flow across dolomite compartments in Gauteng. Incorrect operation of the followingsewage treatment works, can lead to pollution of the surface/groundwater systems in/around theHennops River:o The 50ML/day capacity Hartebeestfontein water treatment works discharges into the easterly

Rietspruit (formerly the Swartspruit) upstream of Rietvlei Dam;o The 38ML/day capacity Olifantsfontein water treatment works discharges into the Olifantspruit

upstream of its confluence with the Sesmylspruit below Rietvlei Dam;o The 35ML/day capacity Sunderland Ridge water treatment works discharges into the Hennops

River upstream of its confluence with the Crocodile River; Additional water quality impacts on local groundwater systems include:

o Below the confluence with the Olifantspruit, the Sesmylspruit features the man-madeCenturion Lake with known quality problems such as algal blooms;

o Informal settlements lacking adequate water and sanitation services (e.g. e-coli, nitrates andsalinity);

o Agricultural practises.

3.2. RainfallAccording to Midgeley (1994), catchment A21B (527km

2) has a mean annual precipitation (MAP) of

672mm/a and a mean annual evaporation (MAE) of 1700mm/a.

3.3. Land-useThe surrounding land-uses include (refer Figure 3.1 & Figure 3.2):

Urban and industrial areas, such as Ladium, Erasmia, Valhalla, Wierdapark and SunderlandRidge;

Numerous agricultural/smallholdings, such as Gerardsville, Raslouw, Sunderland, Deltoidia,Hoekplaas and Mooiplaas. Irrigation takes place on the Mooiplaas and Hoekplaas smallholdingsalong the Hennops River. Poultry farms exist on Vlakplaats 354 JR, Knoppieslaagte 385 JR and355 JR;

The Velmore Hotel is located less than 1km to the east along the M26; The Bayete Function Venue and Day Spa is located on Ptn.4 of Hoekplaats 384 JR some 800m

to the north-northwest; The neighbouring property to the west, along the M26, features The Cheese Shop and the Take a

Break Nursery and Coffee Shop; Hennops Brick & Pave brick works is located to the immediate north of Portion 21 of the farm

Hoekplaats 384 JR; Catwalk Brick Works is located on Ptn.1 of Hoekplaats 384 JR on the opposite side of the M26; An informal settlement is located some 2.5km to the southeast on Potion 7 of the farm

Hoekplaats 384 JR; The PPC dolomite quarry is located some 2km north-northeast on Schurweplaas 353 JR, roughly

1km west of Erasmia; The Sunderland Ridge sewage works with a capacity of 35ML/day is located some 5km upstream

from the subject area, immediately west of the confluence of the Sesmylspruit and the Rietspruit,on the southern bank of the Hennops River;

The Zwartkop Nature Reserve is located between Valhalla, the Sesmylspruit and the R55 some5km east of the subject area;

A domestic refuse site is located some 5.5km to the northeast, opposite the Zwartkop RaceTrack, next to a defunct dolomite quarry (Mittal) between the R55 and the Zwartkop NatureReserve.


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3.4. Morphology and DrainageThe drainage density (Kruger, 1983) does not exceed 2km.km

-2and is classified as “low” to “medium”.

Stream frequency is also classified as “low” to “medium” (0 - 6stream.km-2

).

Catchment A21B is drained by the Hennops River and its tributaries namely the Sesmylspruit belowRietvlei Dam, the Olifantspruit which joins the Sesmylspruit south of Irene as well as the Rietspruitwhich confluence with the Hennops River coincides with that of the Sesmylspruit; and also theSwartbooispruit which joins the Hennops River upstream of its eventual confluence with the CrocodileRiver.

3.5. SoilsThe study area falls within soil mapping unit 11 of the Institute for Soil, Climate and Water (ISCW)broad natural homogeneous soil zone (BNHSZ) regions (Schulze et. al, 1997). This assigns a soildepth of 500 to 1000mm to 80% of unit 11. The remaining 20% of this unit is characterised by soildepths ranging between 100 to 400mm respectively. Unit 11 comprises of 60% SaClLm and 40%SaLm (sandy loam – 10 to 20% clay content) typically supports a medium drainage rate.

3.6. Local SettingPortion 23 of the farm Hoekplaats 384 JR, is located immediately south of the M26. It is 49ha in size.Grasslands are currently used for grazing purposes. The distance to the Hennops River variesbetween 410m to 810m to the north. Existing infrastructure on the property consists of a farmhousewhich is currently occupied by a tenant. Figure 3.3 depicts pertinent site information.

Figure 3.2 Local setting

The following comments relate to surface water and groundwater:

As can be seen in Figure 3.2, the subject area is situated between the Hennops River and theSwartbooispruit which is located some 1.5km to the west. Another small non-perennial drainageline is located some 500m east;

The subject area falls within the boundaries of the Aalwynkop dolomitic compartment. The


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boundaries to this compartment which is also subdivided into a number of sub-compartments arelargely constituted by dykes of low permeability (impermeable at depth) that act ashydrogeological barriers;

Outflow from the Aalwynkop compartment occurs as discharge from the Aalwynkop Spring to thenorthwest;

The site topography slopes to the north-northwest in the direction of the Hennops River:o The topography varies between 1428mamsl (south) and 1364mamsl (north along the M26), at

gradients varying between 0.033 and 0.045;o To the west of the site, the topography slopes to the west in the direction of the

Swartbooispruit, a tributary of the Hennops River.

94250

2858750

2859000

2859250

2859500

94500 94000 93750 93500

2857750

2858000

2858250

2858500

Topography

Geological borehole

Dyke outcrop

Water supply borehole

Portio

nb

oun

da

ry

BH1

BH2

EUB-2

EUB-3

EUB-1

BH3

BH4

BH5

BH6

BH7

BH8

EUB-6

Figure 3.3 Pertinent site information


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4. GEOLOGY

4.1. Regional GeologyThe geology of the study area is portrayed in Figure 4.1 (extract from the published regional 1:50 000geological map; 2528CC LYTTLETON).

Figure 4.1 Regional geological map

The regional geology comprises of strata of the Chuniespoort and Pretoria Groups of the TransvaalSupergroup. The Transvaal Supergroup is characterised by its arcuate distribution around the HalfwayHouse dome and a general dip of 15

0to 25

0towards the northeast and west. The Black Reef

Formation (Vbr) which consists of a basal and upper quartzite separated by dark carbonaceous shaleforms the basal unit of the sequence and is conformably overlain by the carbonates of the MalmaniSubgroup. The Rooihoogte Formation of the Pretoria Group overlies the Malmani Subgroupdisconformably.

The Malmani Subgroup (Vmd) is subdivided into the Oaktree (chert-poor), Monte Christo, Lyttelton(chert-poor), Eccles and Frisco Formations (SACS 1980).

Large tracks of land covering the dolomites are covered by a mantle of red silty soil and residualsolution debris varying considerably in thickness. These were derived from recent dolomite solutionand the weathering of older karst regoliths. The debris consists of angular fragments of chert and grit,sand, clay and manganiferous earth (wad) in various portions.

The presence or absence of chert controls the topographic expression of the dolomite succession.The chert-poor units weather to a smooth topography covered by red silty to clayey soils devoid ofchert. The chert-rich units weather to an uneven topography charaterized by dissolution openings,chert pinnacles and a permeable chert residue with red silty and brown manganiferous soils. Lowdrainage density is indicative of a high degree of leaching.

A characteristic feature of the regional geology is the network of intersecting diabase and syenitedykes as well as syenite sills. These are narrow, vertical, intrusive formations subdividing the dolomiteinto various groundwater compartments. Leakage through dykes is likely to occur. The rate of leakageis controlled by the hydraulic gradient and the permeability of the dyke.

As can be seen in Figure 4.1, the northern boundary of the property coincides with the east-northeasttrending Zwartkop dyke. The northern-most portion of the property is partially transected by the


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southeast trending Pinedene dyke that seems to be displaced between the property’s westernboundary and the M26 further to the west. The southern-most portion of the property is transected bya northeast trending dyke that cuts across both the Pinedene dyke and the Zwartkop dyke as well asthe large syenite sill outcrop coinciding with the southern boundary of the cadastral farm Hoekplaats384 JR. Figure 4.2 is a photograph of this dyke outcrop that was taken at the location indicated inFigure 3.3.

Figure 4.2 North-westerly view of Pinedene dyke outcrop on Ptn.23 of Hoekplaats 384JR

The following comments relate to the likelihood of seismic activity:

According to the Council for Geoscience (CGS, 1992) the region is identified as a Category V(MMS) with only a 10% probability of an event of magnitude 6 (MMS) being exceeded once in aperiod of 50 years;

It is important to note that the site lies outside of the three areas of greatest seismic hazard ofSouth Africa (CGS, 1992);

The South African Bureau of Standards (SABS 1990) issued minimum building requirements tobe implemented in areas it had identified as having inherent seismic risk. No requirements existfor the site.

4.2. Local GeologyThe following description of the local geology were based on 8 exploration boreholes that were drilled(see locations in Figure 3.3):

The depth of exploration boreholes ranged between 19m and 50m deep (average 32m); The only intrusive encountered/penetrated was in BH3, which recorded a syenite intersection

between 15m and 16m deep; Only one borehole, BH4 recorded a water intersection between 23m and 25m deep; No soils were recorded in BH1, BH2, BH3 and to BH4. A soil profile ranging between 0m and 1m

in thickness, and consisting of ferricrete, soil and leached dolomite gravels, were recorded in theremainder of the boreholes;

Leaching ranged between 5m and 17m deep (average 8.9m. The deepest levels of leaching wererecorded in boreholes BH3 (17m) and BH4 (11m);


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The lithological profile recorded in borehole BH5 [WGS84 S25.83078 E28.06007 1373mamsl] ispresented in Table 4.2.

Table 4.2 Geological log – borehole BH50 - 1 Dark grey, medium, chert and leached dolomite fragments - boulders

1 - 2 Pink, medium, leached dolomite and minimal chert

2 - 5 Red grey, medium, leached dolomite and minimal chert

5 - 8 Grey, medium, jointed dolomite, signs of leaching and chert

8 - 15 Pink-red, medium, jointed dolomite, signs of leaching and chert

15 – 16 Pink grey, medium, jointed dolomite, signs of leaching and chert


17 - 18 Dark grey, medium, jointed dolomite, signs of leaching and chert

18 -19 Grey-pink, medium, jointed dolomite, signs of leaching and chert

19 - 20 Pink grey, medium, jointed dolomite, signs of leaching and chert

20 - 22 Light grey, medium, jointed dolomite, signs of leaching and chert

22 - 23 Pink, medium, jointed dolomite, signs of leaching and chert

23 - 27 Grey-pink, medium, jointed dolomite, signs of leaching and chert


28 - 33 Pink grey, medium, jointed dolomite, signs of leaching and chert

33 - 37 Grey-pink, medium, jointed dolomite, signs of leaching and chert



5. HYDROGEOLOGY

5.1. Regional HydrogeologyThe dolomites of the Chuniespoort Group represent one of the most important aquifers in SouthAfrica. According to the Johannesburg 2526 Geohydrologcial sheet, spring flow discharges fromdolomites equates to 120.5Mm

3/a. In comparison (Barnard, 2000), some 315 Mm

3/a were utilised for

irrigation from groundwater abstraction (41.5%), domestic use (3%), mining (50%) andmunicipal/industrial (5.5%).

Leaching of the dolomite and the subsequent development of high to very high storage and permeablehorizons is litho-stratigraphically controlled as the aquifer comprises of an extensive cover of residualsolution debris and in places younger sediments which are underlain by karstified dolomite which isirregular and inhomogenic with hydraulic conditions varying from phreatic to confined. The karstifiedsuperficial zone of the strata acts as the main aquifer, even though fractures that often support highyields can extend to considerable depths in non-karstified dolomite. Intrusions varying in compositionfrom syenite to diabase and dolerite subdivide the dolomite into compartments to form hydrogeologicalunits. Groundwater gradients generally range between 1% and 2% when not influenced by large scaleabstraction. Steps in the water level occur from one sub-compartment to another, validatingboundaries. The low density of surface drainage networks in dolomitic areas suggests high rechargeand significant underground flow which often supports high yielding springs located at the lowestelevation of a compartment in proximity to an impermeable boundary such as a dyke or lithologicalcontact. Overflow or leakage through dyke features in low lying areas where these are weathered nearthe surface is a common occurrence.

The following additional comments relate to the regional hydrogeology:

The groundwater levels in dolomitic aquifers do not necessarily follow the topography:o The generally very shallow gradients are indicative of very permeable formations;o Consequently very deep rest levels may be found in areas of raised topography. Depths

exceeding 100m below surface are not uncommon. Deep water levels in many compartmentsare however the result of dewatering by gold mines as well as overutilization for irrigationpurposes;


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o The Groundwater Resources of the Republic of South Africa Map, sheet 1 & 2, 1995 indicatethe average depth to groundwater as 20m to 30m below surface with a standard deviationrange of 15m to 25m from mean;

The rate and extent of water level drawdown in response to abstraction from dolomitic aquifersare one of the critical factors in the development of ground subsidence and sinkholes:o It is an important consideration in establishing large scale abstraction schemes from the

dolomites;o The risk of subsidence and sinkholes is greatest in areas of shallow groundwater levels

(<30m) and where it fluctuates more than 6m in response to pumping; Boreholes typical yields >5L/s for the area (karst aquifer - dolomitic strata):

o The maximum recorded borehole yield for similar dolomitic aquifers was 126L/s;o Borehole blow yield information sourced from the National Groundwater Database (NGDB)

between Latitude S25.75 to S25.89 and Longitude E28.00 to E28.15 (81 boreholes) rangedbetween 0.1L/s to 40L/s (mean=2.66L/s, median=2L/s);

Porosity and aquifer storage capacity (storativity) values are expected to decrease with depth.Several hydrogeological studies have confirmed this:o A study by Enslin and Kriel (1967) in the Carltonville area indicated that storativity values

decrease from an estimated 9.1% (61m deep) to 1.3% (146m deep);o According to Bredenkamp et. al. (1995), the storativity of dolomitic aquifers generally varies

between 1% and 5%; Natural recharge from rainfall are typically in the order of 7% to 12% of rainfall on an annual basis

as quoted by the following studies:o Bredenkamp (1995), ±7% of MAP;o Kok et. al. (1985) determined that recharge range between 8% and 19% (as a function of

rainfall ranges on an annual basis), an average of 14% of MAP was calculated for the Rietvleiarea;

o Hobbs (1988) estimated recharge for the Irene catchment at 11.1%;o Vegter (1995) indicated the groundwater recharge for the study area to range between 11.2%

(75mm/a) to 16.4% (110mm/a); The Chuniespoort Group groundwater chemistry is summarised in Table 5.1 (223 samples):

o Karst aquifers (dolomitic strata) have a CaMg-HCO3 character;o The natural quality is generally acceptable for any use;o Coefficients of variation greater than 200% for chloride, sulphate and nitrate suggest the

presence of contamination in some of the samples. A Ground Water Quality Management Index of “9” was calculated for the proposed mining area

after the method of Parsons (1995; “Aquifer System Management Classification and AquiferVulnerability Classification”; WRC Report No KV 77/95). Based on this Index of 9, a high level ofgroundwater protection may be required;

The Groundwater Harvest Potential Map of the Republic of South Africa (DWAF, 1986) indicatethe maximum volume of groundwater that may annually be abstracted per surface area topreserve a sustained abstraction, range between 50 000 m

3/km

2/a and 100 000m

3/km

2/a.

Table 5.1 Groundwater chemistry of the Chuniespoort group (223 samples)Variable Minimum Mean Maximum Standard

DeviationCoefficient of

Variation

pH 5.8 7.6 9.5 0.4 5%EC (mS/m) 4.4 62.9 397 56 89%TDS (mg/L) 43.1 443.6 3402 403 91%Ca (mg/L) 1.0 52.7 436 54 102%Mg (mg/L) 1.0 35.4 223 31 88%Na (mg/L) 1.0 24.1 299 39 162%K (mg/L) 0.1 2.3 39 4.2 183%Cl (mg/L) 1.0 37.7 900 83 220%SO4 (mg/L) 1.0 70.5 2172 233 330%T.Alk.(mg/L) 8.0 177.3 664 94 53%NO3 (mg/L) 0.1 5.6 122 12.1 216%F (mg/L) 0.1 0.3 2.8 0.4 133%Langelier Saturation Index(LSI)_

-4.7 -0.4 3.0 1.0

Sodium Adsorption Ratio(SAR)

0.03 0.5 2.9 0.5 100%


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5.2. Local GeohydrologyThe proposed Hoekplaats Dolomite Mine area is located within the Aalwynkop dolomitic compartment.The Aalwynkop and Erasmia dolomitic compartments demonstrate a similar hydrostatic responsepattern and are hydraulically connected along the Sesmylspruit to the east.

5.2.1. Groundwater UseData sourced from the Department of Water Affairs and Forestry’s (DWAF) Water Authorisation andRegistration Management System (WARMS) is summarised in Table 5.2.

Table 5.2 Summary of WARMS groundwater use information – catchment A21B

Topocadastral name UsersAuthorized volume

(m3/annum)

Water use sector

Brakfontein 390 JR 1 6 720 Agriculture: irrigationDoornkloof 391 JR 4 1 143 856 Agriculture: irrigationDoornkloof 391 JR 3 340 444 Agriculture: irrigationEldoraigne Ext 39 1 5 000 Industry (urban)Erand Agricultural Holdings 1 7 774 Agriculture: irrigationErasmia 350 JR 1 101 000 Industry (urban)Exeter 137 JR 1 97 440 Agriculture: irrigationGarsfontein 374 JR 1 1 056 Agriculture: irrigationGlen Austin Agricultural Holdings 1 4 606 Agriculture: irrigationHalfway House Ext 16 1 3 650 Agriculture: irrigationHennopspark Ext 16 1 500 Agriculture: irrigationHoekplaats 384 JR 1 30 000 Agriculture: irrigationKnopjeslaagte 385 JR 7 273 548 Agriculture: irrigationKnopjeslaagte 385 JR 2 29 720 Agriculture: irrigationLekkerhoekie 450 JR 1 3 125 Agriculture: irrigationMagaliesmoot Agricultural Holdings 1 12 050 Agriculture: irrigationMooiplaats 355 JR 2 7 550 Agriculture: irrigationOlifantsfontein 410 JR 1 22 500 Agriculture: irrigationOlifantsfontein 410 JR 1 15 000 Agriculture: irrigationSchurveberg 488 JQ 1 147 825Sterkfontein 401 JR 1 150 600Sterkfontein 401 JR 3 9 360Swartkop 383 JR 1 53 040Sydney 136 JR 1 90 590Timsrand Agricultural Holdings 1 324Vlakplaats 354 JR 2 185 830Witkoppies 393 JR 1 21 965Zwartkop 356 JR 2 13 049Total 45 2 778 422

The Tshwane Metropolitan Council’s groundwater use (22.7Mm3/a) for municipal water supply

purposes are not listed in the WARMS data set (catchment A21B):

Boreholes situated in the Centurion area (catchment A21B) producing some 127L/s (4.01Mm3/a);

The Sterkfontein spring (catchment A21B) which also drains catchment A21A produce some82L/s (2.59Mm

3/a);

The Pretoria Fountains, though situated to the north of catchment A21B, drains this catchment ata rate of roughly 304L/s (9.57Mm

3/a);

The Aalwynkop and Erasmia dolomitic compartments support a number of distributed productionboreholes delivering a combined yield of ±57L/s (1.80Mm

3/a) for municipal water supply

purposes.

5.2.2. HydrocensusA limited hydrocensus was performed across the larger subject area. Apart from the Velmore Hotelwhich has a municipal water connection, a total of 9 points were surveyed (1 borehole on Ptn.23 of thefarm Hoekplaats 384 JR [EUB-6] and 8 external users’ boreholes), all within a 1km radius of theHoekplaats Dolomite Mine property. The reported total daily abstraction recorded within this 1kmradius totals ±38 000 L/d (=38m

3/d = 0.44L/s).


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The surveyed boreholes are indicated in Figures 3.2, 3.3 and 4.1 and summarised in Table 5.3.

A total of 5 water level measurements were recorded and one water sample was taken from theexisting borehole on Ptn.23 of the farm Hoekplaats 384 JR. Borehole depths ranged between 18mand 32m (average 26m).

Table 5.3 Basic hydrocensus informationBorehole Owner Latitude

(WGS 84)

Longitude

(WGS 84)

Abstraction

(L/day)

Groundwater

level depth (m)

Comments

EUB-1 Catwalk Brick WorksJ. NiemandtCell: 082 441 0003

25.82702 28.05621 2 000 9.55 Submersible 32mmBorehole depth = 32m2 000 L reservoir

EUB-2 The Cheese ShopC. KoutzayiotisCell: 083 453 4291

25.82750 28.05880 5 000 - Submersible 5.5Kw2 x 5 000 L reservoirs

EUB-3 Hoekplaats BoerderyJ. SteinbergCell: 082 572 9540

25.82652 28.05843 2 000 9.65 Submersible 0.75KwBorehole depth = 28m

EUB-4 Bayete Day SpaE. MaritzCell: 082 332 5475

25.82021 28.05566 10 000 - Submersible 1.5Kw3 x 5 000 L reservoirs

EUB-5 Hennops Brick & PaveC. VisagieCell: 073 695 4445

25.82125 28.06378 2 000 12.68 Submersible 0.75KwBorehole depth = 18m5 000 L reservoir

EUB-6 Ptn.23 Hoekplaats 384 JRP. JubieCell: 073 153 7054

25.82964 28.06311 1 667 8.99 Submersible5 000 L reservoir

EUB-7 Hennops ValleyNettieCell: 082 331 1705

25.82113 28.06944 15 000 - Submersible2 x 5 000 L reservoirs

EUB-8 MooiplaasLukas SmithCell: 076 471 8436

25.82531 28.07396 2 000 - Submersible2 500 L reservoir

EUB-9 Mooiplaas NurseryW.D. BribnitzCell: 082 461 6102

25.82417 28.07619 20 000 12.5 Submersible 3.5Kwdrought

5.2.3. Depth to Groundwater Level and Hydrostatic FluctuationsFigure 5.1 depicts groundwater table elevations (August/September 2010) and depths for the largerstudy area. The following comments have relevance:

The observed “steps” in the groundwater level across some of the dyke boundaries as well as thewater elevations across the different response units, are highlighted:o A step in the depth to the water table of 16.2m across the Zwartkop dyke between DWA

recorders A2N0757 and A2N0656 to the west of Valhalla;o A step of approximately 9m to 12m further to the south, north of the Sesmylspruit, between

DWA recorders A2N0670 and A2N0669 as well as A2N0660 and A2N0659;o Historical information indicates a substantial step across the southeast trending dyke located

immediately northeast of the Mooiplaats Dolomite Quarry (PPC);o An observation during 2002 indicated the water level elevation in the Mooiplaats Dolomite

Quarry to be around 1347mamsl. This is lower than the groundwater levels observed aroundthe proposed Hoekplaats Dolomite Mine – possibly indicative of localised de-watering aroundthe Quarry;

The 5 water level measurements recorded during the hydrocensus ranged between 9.55m and12.68m (average 10.67m) deep. The groundwater level depth in the on-site borehole (EUB-6)was recorded at 8.99m deep. The quarry is expected to be 40m deep. Consequently mining willoccur ±30m below the natural groundwater table;

The Aalwynkop Spring which drains the Aalwynkop compartment is roughly located at anelevation of 1340mamsl representing the compartment’s decant elevation. By comparison:o The groundwater level in borehole EUB-6, which is situated within the proposed Hoekplaats

Dolomite Mine property is ±1362.5mamsl (topography = 1371.5 and groundwater level =8.99m deep), some 17.5m higher than the Aalwynkop Spring;

o Assuming that the quarry will be 40m deep, the northern regions of the quarry floor isexpected to be at lower elevations than the Aalwynkop Spring.


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To facilitate a comprehensive indication of the hydrodynamic responses in the compartmentalisedgroundwater regime, hydrograph records were sourced for some DWA groundwater monitoringstations across the study area for the period 1986 to 2010. The localities of recorders (A2N0656,A2N0657, A2N0659, A2N0660, A2N0669, A2N0670, A2N0674 and A2N0757) are depicted inFigure 5.1. Groundwater level information for the period August 1988 to August 2010 was plotted andrepresented in Figures 5.2A-C.

Half of the hydrographs recorded a net rise in groundwater levels (0.52m to 0.77m); the other half anet drop in groundwater levels (-0.17m to -0.75m). The overall average mean net change is positive.No signs of prolonged (sustained) monthly declines are evident and no large scale abstraction impactis apparent. The observed fluctuations all fall within the natural hydrostatic fluctuation range (<5m) of atypical dolomitic groundwater environment.

Figure 5.1 Depth to water table and water level elevation distribution

Water Level Fluctuations

-14.00

-13.00

-12.00

-11.00

-10.00

-9.00

-8.00

-7.00

-6.00

-5.00

-4.00

Aug-8

8

Aug-8

9

Aug-9

0

Aug-9

1

Aug-9

2

Aug-9

3

Aug-9

4

Aug-9

5

Aug-9

6

Aug-9

7

Aug-9

8

Aug-9

9

Aug-0

0

Aug-0

1

Aug-0

2

Aug-0

3

Aug-0

4

Aug-0

5

Aug-0

6

Aug-0

7

Aug-0

8

Aug-0

9

Date

Wate

rlev

el(m

)

A2N0660 A2N0669 A2N0670 A2N674

Figure 5.2A Hydrostatic fluctuations in the Erasmia Compartment


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-40.00

-38.00

-36.00

-34.00

-32.00

-30.00

-28.00

-26.00

-24.00

-22.00

-20.00

Aug-8

8

Aug-8

9

Aug-9

0

Aug-9

1

Aug-9

2

Aug-9

3

Aug-9

4

Aug-9

5

Aug-9

6

Aug-9

7

Aug-9

8

Aug-9

9

Aug-0

0

Aug-0

1

Aug-0

2

Aug-0

3

Aug-0

4

Aug-0

5

Aug-0

6

Aug-0

7

Aug-0

8

Aug-0

9

Date

Wate

rlev

el(m

)A2N0657 A2N0659

Figure 5.2B Hydrostatic fluctuations in the Erasmia Compartment


-67

-62

-57

-52

-47

Aug-8

8

Aug-8

9

Aug-9

0

Aug-9

1

Aug-9

2

Aug-9

3

Aug-9

4

Aug-9

5

Aug-9

6

Aug-9

7

Aug-9

8

Aug-9

9

Aug-0

0

Aug-0

1

Aug-0

2

Aug-0

3

Aug-0

4

Aug-0

5

Aug-0

6

Aug-0

7

Aug-0

8

Aug-0

9

Date

Wate

rlev

el(m

)

A2N0656 A2N0757

Figure 5.2C Hydrostatic fluctuations in the Erasmia Compartment

5.2.4. Groundwater Flow DirectionThe direction of groundwater movement from the site is in a north-westerly direction towards theHennops River and the Aalwynkop Spring which drains the Aalwynkop compartment.

5.2.5. Aquifer Yielding PotentialThe reported groundwater use from the existing borehole (EUB-6) on Ptn.23 of the farm Hoekplaats384 JR equates to 0.46L/s for 1hour per day. The yielding potential for the proposed quarrying areaproposed is considered to be low due to the anticipated low volume of effective storage. The dolomiteto be mined is essentially chert-poor and the leaching is limited. The average leaching depth recordedin the 8 exploration boreholes drilled across the proposed area is 8.88mbs and only one of theseboreholes recorded a water intersection.

5.2.6. Groundwater QualityThe water quality results for the groundwater sample collected from borehole EUB-6 are summarisedin Table 5.4. No variable exceeds the guideline concentration (SABS SANS 241:2006 Standard forDrinking Water). The hydro-chemical images (Piper and Durov plots), included as Figure 5.3, confirmthe unimpacted nature of this groundwater sample.

The ambient (background) groundwater quality for the Aalwynkop, Erasmia, West Fountain and theEast and West Doornkloof dolomitic compartments, determined by the average of 13 samples


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analysed for the West Fountain spring recorded between 2002 and 2004 (after Hobbs, Khulani 2004),are also included in Table 5.4. These concentrations also fall within the specified guidelineconcentrations.

Table 5.4 Water quality results for on-site borehole EUB-6 and ambient groundwater quality

EUB – 6 Hoekplaats

Ambientgroundwater

quality

SANS 241 -2006 Domestic Water

Class 1(Recommended Operational

Limit)

Class II (MaxAllowance for

Limited Duration)

Class II WaterConsumptionPeriod, a max

SAMPLED 2010/09/20 2002-2004

pH ( Laboratory) 7.6 7.6 5.0 - 9.5 4.0 - 10.0 No limit

Conductivity (Laboratory) (mS/m) 70 45 < 150 150 - 370 7 years

Total Dissolved Solids (mg/L) 323 283 < 1000 1000 - 2400 7 years

Calcium (mg/L) 65 41 < 150 150 - 300 7 years

Magnesium (mg/L) 39 27 < 70 70 - 100 7 years

Sodium (mg/L) 3.8 12 < 200 200 - 400 7 years

Potassium (mg/L) 0.69 < 50 50 - 100 7 years

Chloride (mg/L) 5.2 29 <200 200 - 600 7 years

Sulphate (mg/L) 30 19 <400 400 - 600 7 years

Nitrate (mg/L) 2.0 2.0 < 10 10 - 20 7 years

Nitrite (mg/L) 0.03

Total Alkalinity (mg/L) 285 206

Silicon (mg/L) 6.2

Ammonia (mg/L) 0.01

Ortho Phosphate (mg/L) <0.01

Fluoride (mg/L) 0.03 <1.0 1.0 - 1.5 1 year

Iron (mg/L) <0.01 < 0.2 0.2 - 2.0 7 years

Manganese (mg/L) <0.01 < 0.1 0.1 - 1.0 7 years

Aluminium (mg/L) <0.01 <0.3 0.3-0.5 1 year

Boron (mg/L) <0.01

20%

40%

60%

80%

20%40%60%80%

20%

40%

60%

80%

20%

40%

60%

80%

20% 40% 60% 80%

20%

40%

60%

80%

20%

40%

60%

80%

20%

40%

60%

80%

Chloride & NitrateCalcium

AnionsCations

EC [mS/m] (10-100)

pH (7-8)

Cl+NO3

SO4

T.AlkNa+K

Mg

Ca

Piper plot Durov plotFigure 5.3 Piper and Durov image plots of the water quality in the proposed mining area as

sampled from borehole EUB-6


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5.2.7. Surface Water QualitySurface water drainage impacting on dolomitic groundwater quality is a distinct reality. The waterquality of the surface water drainage system which features several diffuse and point pollution sourcesacross the larger study area is important and warrants elaboration.

Hydro-chemical data was obtained for two of the Department of Water Affairs and Forestry’s WaterManage System (WMS) Resource Quality Services (RQS) monitoring sites (WMS A21_100000768[Hennops River @ Bridge on M26 – below Sunderland Ridge Sewage Works] and WMSA21_100000773 [Swartbooispruit @ Bridge on M26 – before confluence with Hennops]) for the period2002-06-18 to 2009-07 (See Figure 3.2).

A statistical analysis of selected variables is presented in Table 5.5. Results exceeding the SABSSANS 241:2006 Standard for Drinking Water, are also indicated. Time dependent hydro-chemistrygraphs for WMS sampling localities A21_100000768 and A21_100000773 are presented inFigures 5.4A-C.

The following comments have relevance: The Hennops River upstream of the proposed Hoekplaats Dolomite Mine is indicative of:

o Average ammonia concentrations exceeding Class II (max. allowable for limited duration);o Average nitrate concentration, although compliant is elevated and the average ortho-

phosphate concentration exceeds the wastewater special limit value applicable to discharge ofwastewater into a water resource as outlined in the General Authorisation promulgated inGazette no.26187, Notice no. 399 (published on 26 March 2004 in terms of the National WaterAct, Act No. 36 of 1998);

o The upstream Hennops River EC trend is sideways, and while the nitrate trend is improvingthe ammonia trend is deteriorating;

The Swartbooispruit:o Although the listed average concentrations for Swartbooispruit are all compliant with the

Drinking Water specifications, some concentrations exceed the Class I quality range (Ca andMg), the Class II range (NH4) and the wastewater special limit value (PO4);

o An improving trend is noted for EC and NO3 and a deteriorating trend for NH4; It is clear that the surface water in the study area is of a poorer quality than the background

dolomitic groundwater.

Table 5.5 WMS water quality interpretation (June 2002 to July 2009)WMS A21_100000768

Hennops RiverWMS A21_100000773

SwartbooispruitVariable Min Max Ave 95%ile Min Max Ave 95%ile

pH 7.1 8.8 7.57 7.97 7.3 8.5 7.98 8.3EC (mS/m) 34 108 68 83 27 97 76 88Ca (mg/l) 13 61 35.07 47 7 152^ 63.63 88Mg (mg/l) 8 50 15.28 22.1 11 89^ 43.84 60NO3(N) 0.05 9.5 4.1 7.3 0.05 5 1.5 4.5NH4 0.02 19.3

+5.06

+12.73

+0.05 6

+0.34 0.7

PO4 0.05 4.15 1.45 3.27 0.014 1.1 0.08 0.3SO4 5 132 57 83 25 259 46 69Tot.Alk 87 379 170 240.25 107 466 360 431

Class I (recommended operational limit)^ Class II (max. allowable for limited duration)+ Class II is exceeded


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Electrical Conductivity Trend

0

20

40

60

80

100

120

13-Feb-02 20-Mar-03 23-Apr-04 28-May-05 02-Jul-06 06-Aug-07 09-Sep-08

Date

EC

(mS

m)

WMS A21_100000773 Swartbooispruit WMS A21_100000768 Hennops River

Figure 5.4A EC variations over time

Nitrate Concentration Trend

0

1

2

3

4

5

6

7

8

9

10


Date

NO

3(m

g/l

)


Figure 5.4B Nitrate variations over time

Ammonia Concentration Trend

0

2

4

6

8

10

12

14

16

18

20


Date

NH

4(m

g/l

)


Figure 5.4C Ammonia variations over time


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6. POTENTIAL IMPACTSA mine closure impact rating system, known as “RISKY” was developed by the Institute forGroundwater Studies at the University of the Orange Free State. The software can be used toevaluate the potential impact of a quarry for industrial mineral recovery such as quartz, calcite ordolomite. These types of mining operations will most-likely not pose a threat to the environment. Theselected categories for a typical small-scale operation of this kind are illustrated in Figures 6.1 and 6.2.

Taking cognisance of this first approximation evaluation, the potential impact related to the proposed15 ha dolomite mine on Ptn.23 of the farm Hoekplaats 384 JR is identified and discussed below.

Figure 6.1 Impact assessment on mine/water relationship for silica mining

Figure 6.2 Impact assessment on mine/aquifer relationship for silica mining


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6.1. Identification of Potential ImpactsThe potential impacts on groundwater quality are:

Mining vehicles, mechanical equipment, workshops and fuel facilities may generate diesel/oilleakages/spillages;

Domestic waste may introduce various types of organic and inorganic contamination (at smallvolumes).

Sanitation facilities might pose a localized nitrate and bacteriological contamination problem if amunicipal connection is not possible;

Possible nitrate contamination may also result from:o Rock blasting;o The settlement dam.

The potential impacts on the groundwater quantity primarily relate to the dewatering of the quarry,specifically:

A localized groundwater dewatering cone may manifest around the pit and impact on the yieldingcapacity of the external user’s boreholes;

A certain volume of groundwater base-flow toward the Hennops River and Aalwynkop Spring willbe intercepted.

6.2. Discussion of Potential ImpactsThe following management/mitigation measures, if thoroughly designed, should mitigate most of thecontamination impacts:

Surface water run-off should be controlled in-and-around the proposed plant, quarry, andsettlement pond by a combination of diversion berms and trenches;

The fuel storage/transfer areas, workshop areas, contract serviced oil separators andcontractually serviced portable chemical toilets, should be bund-walled ;

Surface water should be allowed to remain unimpacted, draining freely from the site; The design of the settlement pond liner should be based on:

o Responsible industry standards;o The expected water quality;o Preventing any unnecessary water losses to the subsurface (i.e. water infiltrating through

permeable soil); Proper monitoring should timeously confirm any impacts on the local groundwater quality.

It is likely that a dilution effect will reduce blasting related (increased nitrate concentrations) impacts onthe groundwater quality;

Once the mine intersects the natural groundwater table, groundwater will be pumped from the pit,potentially impacting on the yielding capacity of the two external user borehole’s to the immediate westof Ptn.23 (EUB-1 & EUB-2).

In view of the probable compartmentalisation effect of the Zwartkop dyke (depending on its weatheringstatus) and the anticipated low yielding capacity of the shallow aquifer (being chert-poor, <40m), theimpact on the Hennops River and neighbouring boreholes to the north of the property may potentiallybe insignificant.


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7. RECOMMENDATIONSIt is recommended that the potential impact from the de-watering of the quarry be quantified through a

numeric groundwater model, populated with site specific data. This will entail:

Dedicated hydrogeological boreholes should be drilled:o Four to six boreholes may be required;o Drilled to various depths ranging between 20m and 50m;o Optimally placed across the site, to include testing of the Zwartkop dyke and the aquifer;

Hydrogeological boreholes should be pump-tested to determine:o Hydraulic aquifer parameters;o The compartmentalising effect of the Zwartkop dyke;

In future, the proposed hydrogeological boreholes can be used for:

Dewatering the dolomite rock ahead of mining (resulting in dry in-pit conditions); Groundwater monitoring forming part of the groundwater management strategy required for the

Catchment Management Strategy (CMS).

_____________________________Louis Botha (M.Sc., Pr.Sci.Nat.)for GROUNDWATER SQUARE

file: GW2_215Hoelplaats_GroundwaterAssess_rep.doc


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References

Chief Directorate: Surveys and Mapping. The 1:50 000 Series Topographical Maps 2528CC, CD &DC, 2628AA, AB, AD & DA.

Council for Geoscience, 1978. 1:250 000 Geological Maps, 2528 Pretoria.

DWAF, 1995. Groundwater Resources of the Republic of South Africa, SHEET 1 & SHEET 2.

DWAF, 1999. 1: 500 000 Geohydrologcial map series of the Republic of South Africa, Sheet 2526Johannesburg.

DWAF, October 2000. An Explanation of the 1:500 000 General Geohydrologcial Map Johannesburg2526, HC Barbard.

DWAF, 1996. Groundwater Harvest Potential of the Republic of South Africa.

DWAF, 2002. Republic of South Africa Water Management Areas - Water Availability andRequirements.

DWAF, 2003. Municipal Demarcations of the Republic of South Africa, Task No. Gm653_03.

Midgley DC, Pitman WV, Middleton BJ, 1994. Surface Water Resources of South Africa 1990, Book ofMaps, Volume II, WRC Report No 298/2.2/94.

Parsons R, 1995. A South African Aquifer System Management Classification, WRC Report No KV77/95

Schulze RE, 1997. South African Atlas of Agrohydrology and Climatology, ACRU Report No 46.

Jones & Wagener, 2004. First Interim Report on Sinkholes at Bapsfontein. Report No. JW21/04/9401.

Bredenkamp, DB, 1995. Dolomitic Groundwater Resources of the Republic of South Africa. ReportNo. GH 3857. DWAF.

DWAF. East Rand Dolomite Project, December 1984 – October 1986.

Bredenkamp, DB, Botha, L.J., Van Tonder, G.J. and Van Rensburg, H.J., 1995. Manual onQuantitative Estimation of Groundwater Recharge and Aquifer Storativity based on Practical Hydro-Logical Methods. Water Research Commission. Pretoria.

JMA, June 2005. Formation of Sinkholes in the Bapsfontein Area - Geohydrological Aspects. Ref. No.10275.

Bredenkamp DB, Van der Westhuizen C, Wiegmans FE & Kuhn CM, June 1986. Ground-WaterSupply Potential of Dolomite Compartments West of Krugersdorp, DWAF Technical Report No: GH3440.

PJ Hobbs Khulani Joint Venture, August 2004. Intermediate Groundwater Reserve Determination ForQuaternary Catchments A21A & A21B. Project No. 2002-316.

Sami, K, 2003. Pollution Potential of the Grootfontein Spring and the Rietvlei Boreholes. MothopongConsulting (Pty) Pretoria.

Dr. Fritz Wagener. Sinkholes in the Bapsfontein dolomite water compartment caused by dewatering,Civil Engineering, Vol. 17 No. 3, April 2009.

DWAF, Internal Strategic Perspective: Crocodile West Marico Water Management Area - CrocodileRiver (West) Catchment, Version 1: February 2004.

Hodgson FDI; Usher BOREHOLE, Scott R, Zeelie S, Cruywagen L-M, de Necker E, 2001. Predictiontechniques and preventative measures relating to the post-operational impact of underground mineson the quality of groundwater resources. WRC Report No: 699/1/01. ISBN No: 1-86845-701-X.


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Documents

HOEKPLAATS Dolomite (Pty) Ltd Preliminary … Dolomite (Pty) Ltd Preliminary Groundwater Assessment: Portion 23 (A Portion of Portion 15) of the farm Hoekplaats 384 JR DATE: October