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The threat of mine effluent to the UNESCO status of the Cradle of
Humankind World Heritage Site

JF DURAND,* J MEEUVIS** AND M FOURIE***

Abstract
There is a significant environmental risk posed to the region in which one of the most
important and richest archaeological and palaeontological resources is located in South
Africa. This area, known as the Cradle of Humankind World Heritage (COHWHS), is
situated adjacent to one of the richest gold bearing geological sequence in the world. The
mine pollution which is emanating from the mines in the form of acid mine drainage
(AMD) is threatening this remarkable resource which has yielded the biggest collection of
hominin fossils in the world. The environmental degradation of the COHWHS will have
a major impact on the archaeological and palaeontological heritage of not only South Africa,
but the world, as well as the tourism, hospitality and education sectors of South Africa. If
monitoring, mitigation and management measures are not implemented effectively with
immediate effect to avoid or minimise the negative effects, the COHWHS may stand the
risk of losing its status and be demoted to the UNESCO List of World Heritage in Danger.
Ultimately, if the site loses the characteristics that determined its inscription in the World
Heritage List, the World Heritage Committee may decide to delete the property from its
list.

Keywords: Cradle of Humankind World Heritage Site, Sterkfontein Caves, acid mine drainage,
archaeological and palaeontological resources, dolomite, karst system, risks and impacts

Disciplines: Environmental management, Palaeontology, Archaeology

1. Introduction

The Cradle of Humankind to the north of Krugersdorp on the West Rand in Gauteng was
awarded World Heritage Site status by the United Nations Educational, Scientific and Cultural

* Department of Zoology, University of Johannesburg; (all correspondence should be sent to: fdurand@uj.ac.za).
** Department of Geography and Environmental Management and Energy Studies, University of Johannesburg.
*** PhD candidate in the Department of Geography and Environmental Management and Energy Studies,

University of Johannesburg.

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Organization (UNESCO) in 1999. Its status is based on the unique cultural and natural
heritage contained within this area.

The Cradle of Humankind World Heritage Site is a remarkable South African tourist attraction
and is also acknowledged as an important research resource. The sensitive karst system, in
which the Cradle of Humankind World Heritage is situated, is threatened by urban
development and the unauthorized removal of dolomite, cave formations, fossils and
archaeological artefacts by the public, as well as the over-use of natural resources and pollution
in the area (Durand, 2008). The acidic water decanting from the West Rand pose the most
severe immediate threat to the sensitive and soluble dolomite rock which contains most of the
important palaeontological and archaeological sites of the Cradle of Humankind World
Heritage Site however (Van Eeden et al., 2009).

If these negative impacts are not mitigated in time or become more severe, the Cradle of
Humankind World Heritage Site could be placed on the list of world heritage sites under threat
or even may lose its UNESCO status. More importantly, this could lead to the loss of
irreplaceable archaeological and palaeontological resources (Durand, 2007; Boyd, 2008).

2. Legislative requirements

National guidelines
South Africa possesses some of the world’s most comprehensive and progressive legislation for
the protection and conservation of environmental, archaeological and palaeontological resources
such as the National Environmental Management Act (Act no. 107 of 1998), the Environmental
Conservation Act (Act no.73 of 1989), the National Heritage Resources Act (Act no. 25 of
1999) and the Mineral and Petroleum Resources Development Act (Act no. 28 of 2002). In
terms of the World Heritage Convention Act (Act no.49 of 1999), the unnatural disturbance,
pollution and degradation of the environment must be avoided, or where they cannot be
avoided, mitigated.

In theory, the abovementioned laws, regulations and guidelines provide comprehensive support
for the conservation and sustainable development and use of archaeological and palaeontological
resources of the COHWHS. In practice however it has been found that there is a lack of
expertise and resolve regarding the effective assessment, management and implementation of
legislature regarding archaeological and palaeontological resources. In addition, it seems that
little progress has been made regarding the effective implementation of national environmental
guidelines (Deacon, 2007; Fourie, 2007; Van Eeden et al., 2009). The inability of government
agencies to implement the necessary legislative procedures and the absence of dynamic
management networks within the national/provincial structure in South Africa cause frustration
and confusion amongst various stakeholders, including mining companies, heritage authorities,
archaeological and palaeontological NGOs, environmental consultants and public interest
groups. This is an issue that should be analysed and urgently addressed in order to identify

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potential measures to improve the efficacy of the management of the archaeological and
palaeontological terrains on a national and a provincial level (Deacon, 2007).

Environmental Impact Assessments (EIAs) and Environmental Management Plans (EMPs) are
often complicated by conflicting interpretations of legislation. The legislative requirements of
archaeological and palaeontological specialist studies are often ranked lower in priority
compared to other laws and regulations required for proposed mining development. The
National Heritage Resources Act (Act no.25 of 1999) was only officially promulgated during the
same year as the inscription of the COHWHS and the Department of Arts and the South
African Heritage Resources Agency (SAHRA) has since then been attempting to achieve effective
and efficient implementation of these guidelines, which calls for a proactive, dynamic and
integrated approach towards environmental management (Fourie 2007).

In addition to the aforementioned national legislative requirements, there are a number of
international regulations aimed at the sustainable development and conservation of
archaeological and palaeontological resources which can be used as guidelines for the
development and implementation of heritage policies for South Africa.

International Guidelines
The World Bank stipulates in the Performance Standard 8 of the International Finance
Corporation (IFC) guidelines how cultural and natural heritage resources should be used
sustainably and be conserved during projects, development and operations. In accordance with
the Convention Concerning the Protection of the World Cultural and Natural Heritage,
Performance Standard 8 aims to protect irreplaceable cultural heritage and to guide clients on
protecting cultural heritage in the course of business operations (IFC Guidelines, 2006).

The United Nations Educational, Scientific and Cultural Organization (UNESCO) is dedicated
to the identification, protection and preservation of cultural and natural heritage sites which are
considered to be of outstanding value to humanity. UNESCO World Heritage Sites include
natural features, such as forests, mountains, or man-made structures that are recognised for their
cultural or physical significance to the international community (UNESCO, 2008). Several
World Heritage Sites, both cultural and natural have been inscribed by UNESCO since 1999.

UNESCO’s World Heritage Committee is responsible for the implementation of the World
Heritage Convention, the management of the World Heritage Fund, the identification and
inscription of Wold Heritage Sites and also decides on the inscription or deletion of sites on the
List of World Heritage in Danger.

As defined in Articles 1 and 2 of the Convention, a World Heritage Site can be inscribed on the
List of World Heritage in Danger by the Committee when it finds that the condition of the site
corresponds to one or more of the criteria outlined in Section 177 of the Convention which
deals with the degradation of Heritage Sites. The potential dangers which pose a risk to a
World Heritage Site are described in Section 179 (b) of the Convention and refers to those
threats that would have deleterious effects on its inherent characteristics (UNESCO, 2008).
The most serious threats to the geological and ecological integrity of the COHWHS are certain
agricultural practices, urbanisation and mining (Durand, 2007; 2008).

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3. Area of investigation

Cradle of Humankind World Heritage Site
The Cradle of Humankind World Heritage Site is located approximately fifty kilometres
northwest of Johannesburg and lies across the border between Gauteng and Northwest
Provinces. This 47 000 hectare area is exceptionally rich in archaeological and palaeontological
resources. The COHWHS extends from Krugersdorp in the south to the Hartebeespoort Dam
in the north. This region is not only important from a research and conservation perspective,
but also has significant business and recreational value.

The COHWHS contains more than two hundred caves and fossil localities situated in the
Malmani Dolomite of the Chuniespoort Group which dominates the geology of the area. Due to
the soluble nature of dolomite, the region is pock-marked with solution cavities, caves,
sinkholes, dolines and springs situated between gently undulating hills which is typical of a karst
landscape.

More than a century ago, there was a growing demand on the Witwatersrand for lime which was
used to neutralise the acid solution which remained after the extraction of gold from the crushed
ore. Limestone mines appeared in the Krugersdorp District soon after the Main Reef was
discovered along the length of the Witwatersrand Supergroup. Several of the fossil sites in the
COHWHS were initially utilised as limestone mines.

Palaeontology
The Plio-Pleistocene palaeontological sites in South Africa are situated within the Malmani
Subgroup dolomites in the northern part of South Africa. The abundance of the dolomitic caves
in this region is the main reason for the concentration of heritage resources in the COHWHS.
These dolomitic caves provided shelters for hominids and other predators from approximately 3
million years ago. The bony remains of their prey collected in the caves as part of the cave fill.
The reason for the remarkable preservation of fossil bones in the COHWHS is due to the
alkaline environment created by the dolomite and calcite formations which allows the bones to
be preserved and be mineralised over time.

There are approximately 40 known fossil-bearing sites within the COHWHS and many that fall
outside the borders of the COHWHS. Thirteen of the better known sites, which include sites
that yielded hominid remains, were inscribed as part of the description and declaration of the
COHWHS. These are: Sterkfontein Caves, Bolt’s Farm, Cooper’s Cave, Kromdraai,
Swartkrans, Plover’s Lake Cave, Minnaar’s Cave, Gondolin Cave, Gladysvale Cave, Haasgat
Cave, Drimolen, Motsetsi, and Wonder Cave (See Fig. 1).

The first recorded discovery of fossils at the Sterkfontein Caves was made by a group of students
from the Marist Brothers College in Johannesburg in 1895. Although a member of the South
African Geological Society, David Draper, advised that these caves were worthy of conservation
due to their limestone formations and palaeontological value, mining continued in the vicinity
(Hilton-Barber and Berger, 2002). The discovery of the skull of a juvenile apeman at Taung in
the Northwest Province, in 1924, sensitised people to the importance of the fossils that were

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associated with limestone deposits in South Africa. This apeman was named Australopithecus
africanus, or southern ape of Africa (Dart, 1925).

Figure 1: The most important palaeontological sites in the COHWHS as inscribed by UNESCO

Robert Broom of the Transvaal Museum discovered the first adult apeman skull, albeit very
incomplete and fragmentary, at Sterkfontein in 1936 (Broom, 1936). Broom originally named
this apeman fossil Australopithecus transvaalensis, but later changed it to Plesianthropus
transvaalensis. However, in the light of many subsequent discoveries a convincing argument
could be made that these genera were actually the same. Plesianthropus transvaalensis was finally
renamed to Australopithecus africanus (Broom, 1950).

In 1947 Broom discovered a second adult Australopithecus africanus skull, but this time it was
undistorted and almost complete. The new skull was slightly smaller that the first adult apeman
skull and it was therefore presumed to be that of a female. This, together with the original
binomen Plesianthropus transvaalensis, inspired the nickname Mrs. Ples by which this fossil
became known (Broom, 1950).

Many thousands of fossils have been excavated at Sterkfontein since then; the majority of which
are the remains of mammals which were the prey of carnivores that used the prehistoric caves as
their lairs (Brain, 1981). The Sterkfontein fossil site, which has to date yielded more than half
of all the hominid fossils on earth, may be considered to be the world’s richest hominid site.

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Fossil excavations are still ongoing at Sterkfontein, making it the hominid site with the longest
record of uninterrupted excavations on earth (Hilton-Barber and Berger, 2002).

Robert Broom and his colleagues were responsible for the discovery and exploratory excavations
of the palaeontological deposits at Bolt’s Farm, Cooper’s Cave, Gladysvale, Swartkrans and
Kromdraai where the remains of a second type of apeman, Paranthropus robustus were discovered
(Broom, 1947). Several other fossil-bearing sites were discovered after Broom’s death in 1951,
the most important being Gondolin, Minnaar’s Cave, Plover’s Lake, Haasgat, Drimolen,
Motsetsi Cave and Wonder Cave.

Archaeology
Thousands of stone tools have been discovered in the COHWHS. These tools include
Oldowan hand axes, Acheulean points and microliths. In younger strata pot shards and other
artefacts dating from the Iron Age have been unearthed.

Several dating techniques have been used to date the different palaeontological sites in the
COHWHS, these include: palaeomagnetic surveys, electron spin resonance assessments,
uranium decay series measurements and biochronological and archaeological comparisons. The
palaeontological sites which yielded fossils and tools associated with Paranthropus and early
Homo were dated by using these techniques at between 2 million and 800 000 years (Herries et
al., 2009).

One of the most important discoveries of an archaeological nature in the COHWHS was the
excavation of burnt bones at Swartkrans. These bones were burnt in a fireplace inside the
prehistoric cave at temperatures of up to 500˚C which is interpreted as the oldest proof for the
controlled use of fire (Brain, 1981). The age of this fireplace has been estimated to be between
1 million and 1.5 million years old (Brain, 1983).

4. Threats to the COHWHS

4.1 Mining

4.1.1. Gold
Mining in the vicinity of the COHWHS dates back to the Early Iron Age period where the
descendants of the Sotho and Tswana populations were respected for their metal work and were
part of a dynamic trading community. Other commodities that have been mined in the area
include gold, dolomite and limestone. The Blaaubankspruit Gold Mine was proclaimed in 1875
and the Kromdraai gold mine (in the COHWHS) in 1885. George Harrison discovered the
Main Reef of the Witwatersrand Supergroup on the Farm Langlaagte in 1886. This reef turned
out to be the richest and most extensive gold deposit in the world (Mendelsohn & Potgieter,
1986). During the subsequent year, the Main Reef was traced along the rest of the
Witwatersrand from the West Rand to the East Rand (Viljoen & Reimold, 2002).

As the mining strategies changed from small scale open cast and shallow pit mining methods
along the outcrop of the Main Reef to underground mining, new techniques had to be

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developed to access the rich gold deposits which extended far underground. To extract the gold
of the Witwatersrand, a new mining technique namely deep mining was developed and perfected
in South Africa and has become the proven way to excavate gold in the world. Deep mining
involves the excavation of the gold-bearing reefs, leaving stopes which are connected via incline
and vertical shafts while pillars of natural rock, wood or concrete support the hanging wall.

The gold mines of South Africa have been the foundation of the country’s economic growth for
the past century, producing up to 35% of the world’s gold. Gold mining in the West Rand area
remains one of the most prominent contemporary industries in South Africa with approximately
45% of gold mining originating from the Witwatersrand Basin (Boyd, 2008). Mining
companies with interest in this mineral rich area include Anglo Gold Ashanti Limited, Durban
Roodepoort Deep Gold Limited, Ergo Mining (Pty), Gold Fields, Harmony Gold Mining
Company Limited (now part of Rand Uranium), Mintails South Africa, Pamodzi Gold (West
Rand Mining Operations), Randgold and Exploration Company (Ltd) and the Witwatersrand
Consolidated Gold Resources (Ltd), amongst others (Chamber of Mines, 2008).

4.1.2 Uranium
Radioactive metals were first discovered in the Witwatersrand Supergroup in 1915. The first
plant that produced uranium commercially was built at West Rand Consolidated Mines in 1952
when the strategic importance of nuclear weapons became clear. Waste material from the gold
mines containing uranium and its radioactive daughter products is dumped in slimes dams, wash
down rivers and drain into the groundwater (Coetzee et al., 2006). Although some uranium
extraction takes place on the West Rand (e.g. Uranium One in Carletonville), it is done on a
small scale and is not economically viable. Plans to open a more extensive uranium extraction
plant are underway in the form of Rand Uranium on the old Harmony Gold property in
Randfontein. Great quantities of uranium has been, and still is dumped in the slimes dams on
the West Rand (Coetzee et al., 2006; Winde, 2009)

4.1.3 Dewatering the dolomites
The dolomites of the Malmani Subgroup house an extensive karstic aquifer that supplies most of
the groundwater in these provinces (Hobbs and Cobbing, 2007a). The dolomitic rocks which
overlie the gold-bearing quartzite rocks of the Witwatersrand Supergroup along the southern
part of Gauteng and North West Province had to be dewatered for deep mining to commence
(Warwick et al., 1987; Dreybrodt, 1996). The dewatering of the mine disrupted the normal
recharge and discharge rates of groundwater, it interfered with the natural flow of groundwater
and surface water and it caused sinkholes to be formed in the region (Enslin et al., 1976;
Kleywegt & Pike, 1982; Swart et al., 2003).

4.1.4 Acid mine drainage (AMD)
The auriferous layers of the Witwatersrand Supergroup are characterised by their high gold,
uranium and pyrite (FeS2) content. When pyrite comes in contact with water and oxygen,
sulphuric acid (H2SO4) is produced.

The sulphuric acid content in stagnant water in deep mines become concentrated enough to
dissolve rock and set the metals it contains free. The most common metals released by sulphuric
acid in gold mines on the Witwatersrand include manganese, aluminium, iron, nickel, zinc,

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cobalt, copper, lead, radium, thorium and uranium (Kleywegt, 1977; Venter, 1995; Coetzee et
al., 2006). The high iron content of AMD turns the water orange (See Fig. 2).

The gold mines of the Witwatersrand have been dewatered up to a level of 3km underground for
the best part of a century water. As the mines on the Witwatersrand were abandoned one after
the other after WWII, the mine void left by mining, slowly flooded again. The Western Basin
Mine Void under Krugersdorp and Randfontein alone constitutes 45 million cubic meters.

In 2002, the springs on the West Rand started to flow again after a century, but this time with
AMD containing acid, sulphates and heavy metals. Megaliters of AMD are currently decanting
into the Tweelopiespruit and Wonderfonteinspruit from the Black Reef Incline Shaft and the
no.17 and 18 Winze Shafts as well as from several springs, boreholes and seepage points
(Coetzee and Van Tonder, 2008). The Tweelopiespruit flows through the Krugersdorp Nature
Reserve and into the Rietspruit which in turn flows into the Bloubankspruit. The
Bloubankspruit, which is a tributary of the Crocodile River, flows through the COHWHS.

Figure 2: AMD from Harmony Gold Mine in Robinson Lake in Randfontein

The impact of AMD on the groundwater in the proximity of mines is even worse than that on
surface water bodies. Pollutants remain stagnant in groundwater for many years whereas
pollutants may be flushed out from rivers during heavy rains. AMD reaches the groundwater by
permeating through the rock adjacent to the mine void, the recharge of aquifers and by leaching

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from spoil heaps and mine dumps. It was discovered decades ago that slimes dumps that were
built on the dolomites tended to be more stable and did not collapse as easily as those built on
less permeable surfaces. This stability is caused by the permeable nature of the underlying
dolomite into which the water of the slimes dumps drains.

The structural stability of the dolomites in COHWHS is threatened by the influx of AMD into
the region. Dolomites and limestone are highly soluble in acid which will lead to accelerated
karstification of the affected area. The sulphuric acid in the AMD will dissolve large volumes of
rock as it passes over dolomite and through the dolomitic aquifer. Fissures will widen and
solution cavities will be created in the process. Dolines and sinkholes will form when the surface
collapses into the subterranean void below (Swart et al., 2003; Hodgson et al., 2001).

A high level of sulphates occurs in the groundwater of the region between Harmony Gold Mine
and the COHWHS and in the COHWHS itself (Krige, 2006). Sulphates are formed as a by-
product of the chemical reaction between sulphuric acid and dolomite and can therefore be used
as an indication of the presence of AMD in a dolomitic region.

4.2 Tourism and Business Development
The area between the western part of the Witwatersrand and Magaliesberg Mountains was used
for farming from the late 19th Century to the present. Even today there are approximately 700
farms or smallholdings in the COHWHS, many of which are used to produce crops and have
livestock (Hamann, 2004). Although gold mining became the primary foundation of the region’s,
and indeed the country’s, economic prosperity after 1886, the focus more recently shifted to
include tourism, manufacturing, agribusiness and recreational development (Mogale City Local
Municipality, 2008).

Owing to its geographical proximity to major cities and airports like O.R Tambo and Lanseria
International Airports, there has been an evident increase in residential and ,light industrial
development on the West Rand. The agricultural, horticultural and animal husbandry practices
in this area tend to be more intensive than in neighbouring provinces, where it is more common
to have free ranging cattle grazing on natural veld and low density farming. It is reported that
the agricultural and farming activities of the Western regions of Gauteng can only sustain high
density farming such as piggeries, chicken batteries and feedlots due to limited veld and available
water resources (Durand, 2007). Overall, the Gauteng Province seems to be more focused on
industrial development and mining.

With reference to tourism development, the Cradle of Humankind World Heritage Site region
currently consists of approximately 387 tourist attractions and more than 90 graded
establishments. As part of the sustainable development and conservation of the Cradle of
Humankind World Heritage Site area, the Gauteng Provincial Government’s Management
Authority invested an estimated amount of R189 million in roads and bulk infrastructure to
develop the site and motivate private sector investment in tourism development. In October
2003, the Gauteng Provincial Government entered into a contract valued at R163 million with
Maropeng a'Afrika Leisure (Pty) Ltd for the construction, design and operation of world class
visitor exhibition and recreational facilities at the Cradle of Humankind World Heritage Site.
This Public Private Partnership is an unique concession agreement, requiring Maropeng a'Afrika
Leisure (Pty) Ltd to pay an annual concession fee that the government will invest in community

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benefit projects and in scientific research (Gauteng Provincial Government, 2008). In addition
to numerous tourist attractions and graded establishments, there are in excess of 175
accommodation establishments, 113 restaurants, 70 conference venues and 44 wedding venues
in and around the Cradle of Humankind World Heritage Site. These tourism establishments
directly employ an estimated 7 000 permanent employees and 2 200 casual employees.

In February 2008, the Cradle of Humankind World Heritage Site and Dinokeng Blue-IQ
projects received the Sustainable Tourism Investment of the Year award at a gala ceremony at
the Hyatt Regency Hotel in Johannesburg. These two Blue-IQ projects are an initiative of the
Gauteng Provincial Government to establish geo-spatial tourism destinations in the northwest
and the northeast of the province (Mogale City, 2008). It is evident that the economic
prosperity of tourism is directly linked to the conservation of archaeological and
palaeontological resources found in the Cradle of Humankind World Heritage Site area. As
main tourist attraction in this area, the conservation of these resources and the limestone caves
associated with the fossillferous deposits, is therefore of paramount importance for the
sustainable development of the regional tourism industry.

Although it is essential that these irreplaceable archaeological, palaeontological and geological
resources need to be conserved in order to protect the status of the COHWIS, there is
increasing evidence that the decant of mine effluent in the West Rand area threatens the
sensitive karst environment of the COHWHS (Durand, 2007; Durand, 2008; Van Eeden et al.,
2009).

5. Potential Risks

In South Africa and specifically in the COHWHS, the karst system associated with dolomitic
environments is threatened by various elements, including groundwater pollution, urban
development, vandalism and unauthorized removal of fossils or cave formations by the public, as
well as the over-use of natural resources in the area (Durand, 2007). The most significant risk
to the archaeological and palaeontological resources in the Cradle of Humankind World
Heritage site is associated with surface- and groundwater pollution, more specifically acid mine
drainage. AMD decanting from the mine void into the karst system has penetrated the
dolomitic Zwartkrans Compartment below the mine property, the Krugersdorp Nature Reserve
and the southern part of the COHWHS (Krige, 2006; Oelofse et al., 2007; Hobbs and
Cobbing, 2007a; 2007b; Coetzee et al., 2009.). Mine effluent is now decanting from the
Zwartkrans Compartment into the Northern dolomitic compartment in the northern part of the
COHWHS (Krige, 2006). In addition to the AMD, the COHWHS has also been affected by
effluent discharge from municipal waste treatment works, and especially from the Percy Steward
Sewage works (Hobbs and Cobbing, 2007a; 2007b).

The solubility and permeability of the sensitive karst system in the Cradle of Humankind World
Heritage area makes it especially susceptible to water pollution and environmental degradation.
The effects of acid mine drainage on dolomitic environments and karst systems could cause sink
holes, irreversible damage to the karst system and surrounding dolomitic environment and
irreparable damage to archaeological and palaeontological resources contained in this area. Acid
mine drainage has the potential to dissolve any dolomitic geological structure on its dispersion

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route, including the vulnerable dolomitic in the Cradle of Humankind World Heritage Site that
accommodates various fossils and archaeological and palaeontological resources (Durand, 2007).

The legacy of environmental mismanagement of the water resources entering the COHWHS is
evidently becoming an increasing concern for stakeholders and communities in this area who
depend almost entirely on groundwater for drinking and irrigation purposes. Due to the
potential harmful effects of acid mine drainage in this area, negative impacts pose severe risks to
the health and well-being of humans, animals and the environment, as well as the status of the
Cradle of Humankind World Heritage Site (Durand, 2007; Van Eeden et al., 2009; Winde,
2009). In order to quantify and comprehend the significance of potential impacts on
archaeological and palaeontological resources in the Cradle of Humankind World Heritage Site,
an impact assessment is required.

6. Impact Assessment

6.1. Impact assessment rating
The impact rating process is designed to provide a numerical rating of the various environmental
impacts identified by use of the “Input-Output” model. The purpose of the impacts assessment
process is not to provide an incontrovertible rating of the significance of various aspects, but
rather to provide a structured, traceable and defendable methodology of rating the relative
significance of impacts in a specific context (DWA and PGS, 2009). The significance rating
process follows the established impact/risk assessment formula: Significance = Consequence x
Probability; where: Consequence” = Severity + Spatial Scale + Duration; and Probability is
determined with reference to industry knowledge and instances of impacts happening in similar
instances. The significance rating of archaeological and palaeontological sites is generally also
based on four main criteria:

• Site integrity (i.e. primary vs. secondary context),

• Amount of deposit, range of features (e.g. stone tools and enclosures),

• Uniqueness and

• Potential to answer present research questions.

Management actions and recommended mitigation are expressed as follows:

A - No further action necessary;

B - Mapping of the site and controlled sampling required;

C - Preserve site, or extensive data collection and mapping of the site; and

D - Preserve site

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For the purpose of the impact and risk assessment of archaeological and palaeontological
resources in the COHWHS, site significance classification standards prescribed by the South
African Heritage Resources Agency (SAHRA), approved by the Association for Southern African
Professional Archaeologists (ASAPA) for the Southern African Development Community
(SADC), were utilised. The integrated impact assessment approach and associated ratings that
were utilised in this assessment have been summarised in the following tables (National Heritage
Resources Act, 1999 and DWA and PGS, 2009):

Site Significance (SAHRA and ASAPA)

FIELD RATING GRADE SIGNIFICANCE RECOMMENDED MITIGATION

National Significance
(NS)

Grade 1 - Conservation; National Site nomination

Provincial Significance
(PS)

Grade 2 - Conservation; Provincial Site
nomination

Local Significance (LS) Grade 3A High Significance Conservation; Mitigation not advised

Local Significance (LS) Grade 3B High Significance Mitigation (Part of site should be
retained)

Generally Protected A
(GP.A)

- High / Medium
Significance

Mitigation before destruction

Generally Protected B
(GP.B)

- Medium Significance Recording before destruction

Generally Protected C
(GP.C)

- Low Significance Destruction

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Severity (Positive and Negative Impacts)

5 Very significant impact/total destruction of a highly valued species, habitat or ecosystem in
the environment; or Irreparable damage to/destruction of highly valued items of great cultural
significance

4 Serious impairment of ecosystem function or Serious social issues/Permanent damage to
items of cultural significance

3 Moderate negative alteration of ecosystem functioning or Moderately important social issues
and/or moderately significant damage to items of cultural significance

2 Minor effects not affecting ecosystem functioning or Minor Impacts on the local population,
repairable over time. Temporary impairment of the availability of items of cultural
significance

1 Insignificant effects on the biophysical environment or Insignificant social issues / low-level
repairable damage to commonplace structures.

Spatial Scale/Extent

5 National/International (Neighbouring countries or abroad)

4 Provincial or Regional (Gauteng Province)

3 Regional (substantially beyond site boundary; more than 5 km)

2 Local (beyond site boundary and affects neighbours; up to 5km from site)

1 Site (does not extend beyond site boundary, Cradle of Humankind area)

Duration

5 Permanent/Irreversible (more than 50 years)

4 Long Term (26 to 50 years or beyond)

3 Medium Term (5-25 years)

2 Medium-Short Term (1-4 years)

1 Short term (Less than a year)

Durand,
Meeuvis
and
Fourie

Probability

5 Certain/ Normally happens in cases of this nature (81-100% chance)

4 Will more than likely happen (61-80% chance)

3 Could happen and has happened here or elsewhere (41-60% chance)

2 Has not happened yet, but could (21-40% chance)

1 Conceivable, only very specific circumstances, not likely (0-20% chance)

6.2. Impact assessment and AMD in the COHWHS
The COHWHS is considered to be of national and international significance and consequently
classified as a site of National Significance (NS, Grade 1) (National Heritage Resources Act,
1999). As indicated in Table 1, this World Heritage Site may be severely threatened by the
potential impact of surface- or groundwater pollution and the infiltration of acidic water with
pH values between 2-4 into the sensitive dolomitic environment. The risks posed to the Cradle
of Humankind World Heritage Site is due to the solubility and permeability of the sensitive
karst system that could cause sinkholes, irreversible damage to the karst system and surrounding
dolomitic environment and irreparable damage to archaeological and palaeontological resources
contained in this area (Durand, 2007). Recent reports indicate that acidity levels of between
pH2 and pH4 have already been recorded and documented, verifying the possibility of a
medium to high significance impact assessment rating to the COHWHS (Van Eeden et al.,
2009, Hobbs and Cobbing, 2007a and Boyd 2008).

In order to mitigate these impacts or risks, the decanting of acid mine drainage from mine
workings on the West Rand that causes these impacts and associated surface- and groundwater
pollution, must be ceased. Alternatively, where the activities associated with the impacts cannot
be ceased, it must be mitigated. As indicated in Table 2, this implies that the mine effluent (acid
mine drainage and polluted water) must be treated at a water treatment plant and a programme
must be implemented to continuously monitor and manage water quality (Hobbs and Cobbing,
2007a; Boyd, 2008; Coetzee and Van Tonder, 2008). The effective implementation of these
mitigation measures would require integrated cooperation between various stakeholders and
assist to restore water quality to acceptable levels in the Cradle of Humankind World Heritage
area. Ultimately, the mitigation and restoration of water quality in the region may decrease the
risks and associated impacts significance rating from medium-high to medium-low.

7. Conclusion

Environmental management is a multi-disciplinary concept that is especially important in large
scale industrial developments such as gold mining, that have the potential to negatively affect the
environment and its resources. Although South Africa possesses some of the world’s most
progressive environmental guidelines and legislation, the practical implementation of these

Mine
effluent
and
the
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of
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World
Heritage
Site

TD, 6(1), July 2010, pp. 73 – 92.

guidelines and recommendations by specialists are often constrained by limitations such as a lack
of authority, lack of funding, lack of human resources, a lack of proactive environmental
management and pressing time constraints (Deacon, 2007; Fourie, 2007). The ineffective
implementation of national guidelines and legislative requirements can subsequently lead to
environmental disasters that are difficult to mange or control such as water pollution, health
risks and environmental degradation (Van Eeden et al., 2009).

Gold mining and mineral extraction on the West Rand has played an important role in the
socio-economic development of South Africa; however, the negative impacts and legacies of
environmental mismanagement are becoming an increasing concern for the communities and
environmental stakeholders, especially on the West Rand, including the COHWHS (Coetzee et
al., 2006; Boyd, 2008; Van Eeden et al., 2009).

AMD emanating from the mine void on the West Rand poses a threat to the structural stability
of the karst system of the region. Acid containing mine effluent may lead to irreparable damage
to the archaeological and palaeontological resources in the COHWHS (Durand, 2007). In
addition, it may pose health, safety and environmental risks to surrounding communities (Van
Eeden et al., 2009). Site significance ratings for the Cradle of Humankind World Heritage Site
has been classified as being medium-high.

In terms of UNESCO criteria, the site could risk losing its World Heritage Site status if these
impacts and risks are not mitigated. Where a property has deteriorated to the extent that it has
lost those characteristics which determined its inclusion in the World Heritage List, the
UNESCO Committee may consider the deletion of a property or site from the World Heritage
List (UNESCO, 2008).

An integrated mitigation plan must be implemented by all the stakeholders concerned, including
governmental authorities, mining companies and interest groups, followed by continuous water
management and monitoring (Hobbs and Cobbing, 2007a; 2007b). Ultimately, the integrated
significance of environmental management as a multi-disciplinary concept must be understood
before it can be effectively implemented. The medium-high significance ratings of irreplaceable
heritage in the COHWHS may be reduced by prompt and decisive intervention.

The poisoning of the water on which thousands of people rely for drinking and farming
purposes, the loss of the UNESCO status and the resulting loss of potential income in the form
of tourism may be considered to be a crime towards the people of South Africa. The damage to
the unique palaeoanthropological wealth of the COHWHS, which is essential for our
understanding of human evolution, may be considered to be a crime against humanity.

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Table 1: Summary of potential impacts

Table 2: Summary of recommended mitigation and management measures

ACTIVITY OBJECTIVES
MITIGATION/

MANAGEMENT FREQUENCY APPLICABLE LAWS/ REGS ACTION PLANS
RESPONSIBLE

PERSON

SIGNIFICANCE
AFTER

MITIGATION

Decanting of
acid mine

drainage from
mine workings

on the West
Rand causing
Surface- and
groundwater

pollution

To facilitate conservation
and ensure the

protection of geological,
archaeological and
palaeontological

resources in the Cradle
of humankind World

Heritage area

Treatment of
acidic water and

acid mine
drainage being

decanted into the
environment at
water treatment

plant

Continuous
(Long term)

World Heritage Convention Act (Act
no. 49 of 1999), National

Environmental Management Act (Act
no. 107 of 1998), Environmental
Conservation Act (Act no. 73 of

1989), National Heritage Resources
Act (Act no. 25 of 1999), and

Minerals & Petroleum Resources
Development Act (Act no.28 of

2002)

Effective
treatment of
mine effluent

(acidic/polluted
water), and
Continuous
Hydrological

management and
monitoring

Governmental
departments (i.e.

Local and National
Departments of

Water and
Environmental

Affairs), Mining
Companies and
working groups

Medium-low
significance

SITE IMPACT/ RISK PROBABILITY SPATIAL SCALE /
EXTENT

DURATION SEVERITY SAHRA & ASAPA
SITE

SIGNIFICNACE

SIGNIFICANCE
BEFORE

MITIGATION

Cradle of Humankind World
Heritage Site consisting of

various caves and fossils in a
sensitive karst system/

dolomitic environment on the
West Rand, Gauteng Province,

South Africa

Infiltration of
surface- or

groundwater
with pH values
between 2 to 4

(or lower)

3 – Could happen and
has happened here or
elsewhere (41-60%

chance)

3 – Regional
(substantially
beyond site

boundary; more
than 5 km)

5 – Permanent/
Irreversible (more

than 50 years)

4 - Serious
impairment of

ecosystem function
or Serious social

issues/ Permanent
damage to items of
cultural significance

National
Significance

(NS)

Grade 1

Medium to High
significance
(Immediate
Mitigation
required)