1 000 mw kobong pumped storage scheme on the katse dam ... - Iliso

1 <strong>000</strong> MW KOBONG PUMPED STORAGE SCHEME ON 

THE KATSE DAM RESERVOIR 

WATER QUALITY IMPACT ASSESSMENT REPORT 

DISCLAIMER 

ILISO Consulting (Pty) Ltd assumes no 

responsibility for any errors that may appear in 

this document. The information contained in 

this document is subject to change without

Water Quality Assessment Report 

Proposed 1<strong>000</strong> MW Kobong Pumped Storage Scheme on the Katse Dam Reservoir 



Report Title: Water Quality Assessment Report 

Authors: Carol Hooghiemstra and Martin van Veelen 

ILISO project reference no.: 1100373 

Status of report: Draft v.0.3 

First issue: July 2012 

Final issue: 

Approved for ILISO Consulting (Pty) Ltd by: Approved for the Lesotho Highlands 

Water Commission by: 

________________________________________ ___________________________________ 

Dr Martin van Veelen Mr Charles Mwakalumbwa 

Director: ILISO Consulting Secretary: Lesotho Highlands Water 

Commission 

Prepared by: 

ILISO Consulting (Pty) Ltd Contact: Martin van Veelen 

P O Box 68735 Tel: +27 12 685 0900 

Highveld Fax: +27 12 665 1886 

0169, South Africa E-Mail: martin@iliso.com 

July 2012 i




TABLE OF CONTENTS 


1. INTRODUCTION .......................................................................................................... 1-1 

1.1 BACKGROUND.......................................................................................................... 1-1 

1.2 PURPOSE OF THE EIA STUDY .................................................................................. 1-2 

1.3 PURPOSE OF THIS STUDY......................................................................................... 1-3 

1.4 TERMS OF REFERENCE ............................................................................................ 1-4 

1.5 AUTHOR’S CREDENTIALS AND DECLARATION OF INDEPENDENCE................................ 1-4 

1.6 STRUCTURE OF THIS REPORT................................................................................... 1-4 

2. DESCRIPTION OF THE PROPOSED PROJECT........................................................ 2-5 

2.1 DESCRIPTION OF THE PROPOSED INFRASTRUCTURE.................................................. 2-5 

2.2 DESCRIPTION OF THE PROPOSED DEVELOPMENT PROCESS ....................................... 2-8 

3. METHODOLOGY ......................................................................................................... 3-1 

3.1 BASELINE CHARACTERISATION................................................................................. 3-1 

3.2 IMPACT ASSESSMENT .............................................................................................. 3-1 

3.3 MITIGATION MEASURES............................................................................................ 3-4 

4. DESCRIPTION OF THE RECEIVING ENVIRONMENT............................................... 4-1 

4.1 LOCATION OF ACTIVITY............................................................................................. 4-1 

4.2 LANDSCAPE AND LANDUSE ....................................................................................... 4-8 

4.2.1 Access Routes ................................................................................................... 4-8 

4.2.2 Nature and Conservation ................................................................................... 4-9 

4.2.3 Agriculture.......................................................................................................... 4-9 

4.2.4 Construction Industry ....................................................................................... 4-10 

4.2.5 Recreation and Tourism................................................................................... 4-10 

4.2.6 Residential ....................................................................................................... 4-11 

4.3 TOPOGRAPHY AND GEOLOGY ................................................................................. 4-11 

4.4 CLIMATE................................................................................................................ 4-12 

4.5 VEGETATION AND BIODIVERSITY ............................................................................. 4-14 

4.6 SOCIO-ECONOMIC STATUS ..................................................................................... 4-15 

5. SURFACE WATER QUALITY STATUS .................................................................... 5-18 

5.1 AVAILABILITY OF DATA ........................................................................................... 5-18 

5.2 VARIABLES OF CONCERN....................................................................................... 5-20 

5.3 FITNESS FOR USE.................................................................................................. 5-25 

5.3.1 Identification of fitness-for- use ........................................................................ 5-25 

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5.3.2 Combined Fitness-For-Use Classification........................................................ 5-26 

5.4 DATA ANALYSIS..................................................................................................... 5-34 

5.5 WATER QUALITY ASSESSMENT............................................................................... 5-34 

6. IMPACT ASSESSMENT .............................................................................................. 6-1 

6.1 PRE-CONSTRUCTION PHASE: ................................................................................... 6-1 

6.1.1 Surface water quality ......................................................................................... 6-1 

6.2 CONSTRUCTION PHASE............................................................................................ 6-4 

6.2.1 Impacts of the upper reservoir on the upper tributaries of the Kobong River .... 6-5 

6.2.2 Surface water quality ......................................................................................... 6-5 

6.2.3 Stor<strong>mw</strong>ater....................................................................................................... 6-13 

6.2.4 The operational phase ..................................................................................... 6-14 

7. MITIGATION MEASURES ........................................................................................... 7-1 

7.1 OPERATIONAL PHASE .............................................................................................. 7-8 

8. CONCLUSIONS AND RECOMMENDATIONS............................................................ 8-1 

LIST OF TABLES 

TABLE 2-1: RESERVOIR AREA AND VOLUME FOR UPPER DAM SITE.......................................... 2-8 

TABLE 3-1: GEOGRAPHICAL EXTENT OF IMPACT ...................................................................... 3-2 

TABLE 3-2: DURATION OF IMPACT........................................................................................... 3-2 

TABLE 3-3: INTENSITY OF IMPACT........................................................................................... 3-3 

TABLE 3-4: PROBABILITY OF IMPACT....................................................................................... 3-3 

TABLE 3-5: CONFIDENCE IN LEVEL OF KNOWLEDGE OR INFORMATION ...................................... 3-4 

TABLE 3-6: SIGNIFICANCE OF ISSUES (BASED ON PARAMETERS) .............................................. 3-4 

TABLE 4-1:TEMPERATURE CHARACTERISTICS FOR KOBONG SITE (APPROX. LOCATION; ALTITUDE 2 

300 M): KEY: TEMP. = TEMPERATURE................................................................. 4-13 

TABLE 4-2: PRECIPITATION CHARACTERISTICS FOR KOBONG SITE (APPROX. LOCATION; ALTITUDE 

2 300 M): KEY: PRECIP. = PRECIPITATION........................................................... 4-14 

TABLE 5-1: LESOTHO HIGHLANDS DEVELOPMENT AUTHORITY WATER QUALITY MONITORING 

STATIONS IN THE KATSE DAM............................................................................... 5-18 

TABLE 5-2: COLOUR CODES ASSIGNED TO FITNESS FOR USE RANGES.................................... 5-25 

TABLE 5-3: USER SPECIFIC GUIDELINES: DOMESTIC (DWAF, 2006) ..................................... 5-27 

TABLE 5-4: USER SPECIFIC GUIDELINES: INDUSTRIAL (DWAF, 2006).................................... 5-28 

TABLE 5-5: USER SPECIFIC GUIDELINES: AGRICULTURE & ECOLOGY (DWAF, 2006)............. 5-29 

TABLE 5-6: COMBINED FITNESS-FOR-USE CATEGORIES........................................................ 5-31 

TABLE 5-7: WATER QUALITY ASSESSMENT CATEGORY........................................................... 5-33 

TABLE 5-8: VARIABLES THAT ARE ANALYSED AS PART OF THE WATER QUALITY MONITORING 

PROGRAMME IN THE KATSE DAM .......................................................................... 5-36 

TABLE 5-9: FITNESS FOR USE OF THE WATER QUALITY IN THE KATSE DAM ............................ 5-37 

TABLE 6-1: SIGNIFICANCE TABLE OF IMPACTS ON WATER QUALITY DURING THE PRE- 

CONSTRUCTION PHASE .......................................................................................... 6-3 

July 2012 ii



TABLE 6-2: SIGNIFICANCE TABLE ASSOCIATED WITH SPILLAGES OF HYDROCARBONS DURING THE 

CONSTRUCTION PHASE .......................................................................................... 6-6 

TABLE 6-3: SIGNIFICANCE TABLE FOR CONTAMINATED RUNOFF FROM THE CONSTRUCTION YARD, 

CRUSHING AND BATCH PLANTS ............................................................................... 6-7 

TABLE 6-4: SIGNIFICANCE TABLE FOR THE SPILLAGES OF DANGEROUS GOODS......................... 6-8 

TABLE 6-5: SIGNIFICANCE TABLE FOR WATER DISCHARGED WITH A HIGH CONCENTRATION OF 

SUSPENDED SOLIDS............................................................................................... 6-9 

TABLE 6-6: SIGNIFICANCE TABLE FOR WASTE MANAGEMENT.................................................. 6-11 

TABLE 6-7: SIGNIFICANCE OF THE PROVISION OF SANITATION ................................................ 6-12 

TABLE 6-8: IMPACTS ASSOCIATED WITH THE CONSTRUCTION OF RIVER CROSSINGS................ 6-13 

TABLE 6-9: IMPACT ASSOCIATED WITH STORMWATER MANAGEMENT ...................................... 6-14 

TABLE 6-10: IMPACT ASSOCIATED WITH THE OPERATIONAL PHASE OF THE PROJECT............... 6-15 

TABLE 7-1: ENVIRONMENTAL MANAGEMENT PROGRAMME FOR THE CONSTRUCTION PHASE..... 7-1 

LIST OF FIGURES 

FIGURE 2-1: DESCRIPTION OF THE KOBONG PUMPED STORAGE SCHEME ................................ 2-6 

FIGURE 4-1: THE GENERAL LOCATION OF THE KOBONG PUMPED STORAGE SCHEME................ 4-2 

FIGURE 4-2: THE PROPOSED SITE LAYOUT OF THE KOBONG PUMPED STORAGE SCHEME......... 4-3 

FIGURE 4-3: PROPOSED TRANSMISSION LINE ROUTE AS SURVEYED BY HELICOPTER................ 4-4 

FIGURE 4-4: PHOTOGRAPHIC OVERVIEW OF THE GREATER SITE............................................... 4-7 

FIGURE 4-5: MAFIKA-LISIU PASS THROUGH THE LESOTHO HIGHLANDS .................................... 4-8 

FIGURE 4-6: VIEW OF BOKONG NATURE RESERVE ................................................................. 4-9 

FIGURE 4-7: AGRICULTURAL LAND ......................................................................................... 4-9 

FIGURE 4-8: VIEW OF SURROUNDING INFRASTRUCTURE ....................................................... 4-10 

FIGURE 4-9: TOURIST ACCOMMODATION AT BOKONG NATURE RESERVE .............................. 4-10 

FIGURE 4-10: LOCAL VILLAGE RESIDENTIAL DWELLINGS ....................................................... 4-11 

FIGURE 4-11: SENSE OF PLACE SHOWING VIEW OF MALUTI MOUNTAINS ............................... 4-12 

FIGURE 4-12: SITE OF PROPOSED KOBONG DAM SHOWING EXISTING VEGETATION................. 4-15 

FIGURE 4-13: POPULATION GROWTH RATES: 1976 TO 2006 ................................................ 4-17 

FIGURE 5-1: LOCALITY OF THE MONITORING POINTS.............................................................. 5-19 

July 2012 iii



EXECUTIVE SUMMARY 

The Lesotho Highlands Water Commission (LHWC) has appointed ILISO Consulting (Pty) 

Ltd in association with Sechaba Consultants, to undertake an Environmental Impact Study 

(EIS) in compliance with the Lesotho Environment Act of 2008 for the proposed 1 <strong>000</strong> MW 

Kobong Pumped Storage Scheme. The EIS is required to address potential impacts that 

might be associated with the proposed project, and to provide an assessment of the project 

in terms of the biophysical, social and economic environmental factors. 

The project will comprise of: 

• A new 101 m high dam (i.e. the upper reservoir) on the Kobong River that has a Full 

Supply Level of approximately 2604 meters above sea level and is expected to 

inundate approximately 0.5 km2 when full; 

• An intake tower on the upper reservoir; 

• A headrace tunnel (4 270 m, 11.5 m diameter, 12.1 % inclination), with penstocks 

and a surge arrestor; 

• An underground 1 <strong>000</strong> MW power station; 

• A tailrace tunnel (1 050 m long, 6.3 m diameter) and outlet tower at the Katse Dam 

(i.e. the lower reservoir); 

• A 65 km long 400 kV transmission line from the powerhouse running north to 

Maputsoe near Lesotho’s border with South African – the power line will follow the 

existing feeder road from Kobong to the Katse intake, and from there it will run 

parallel to the existing transmission line; 

• A switchyard near the Katse Dam; and, 

• Construction specific infrastructure. 

No water quality data was available for the Kobong River especially in the upper reaches 

where the proposed upper reservoir will be constructed. The upper reaches of the Kobong 

is directly dependent on rainfall and melting snow in winter. 

Water quality data for the Katse Dam was obtained from the Monitoring and Evaluation 

Manager of the Lesotho Highlands Development Authority (LHDA) for the water quality 

monitoring programme that is implemented in the catchment. 

Variables of concern that may have an impact on the Pumped Storage Scheme or which 

could be expected to be impacted on during the construction and/or operational phase of the 

project were compared with the South African Water Quality Guidelines (DWAF, 2006). 

July 2012 iv



These variables included temperature, pH, Alkalinity, Total Dissolved Solids (TDS) /Electrical 

Conductivity (Ec), Suspended Solids (SS), Nitrate/Nitrite, Ammonia, Phosphate, Chloride, 

Sulphate Silica, Iron, and Manganese. 

The water quality data was analysed by determining the median, the 75 th percentile and the 

95 th percentile. From the data it could be determined that the water has a low alkalinity and 

a medium pH between 8 and 9. The medium temperature of the various monitoring points 

varied between 14°C and 17°C. The electrical conductivity was below 10 mS/m with the 

sulphate concentrations below 10 mg/ℓ, sodium below 5 mg/ℓ and magnesium below 5 mg/l. 

It further appears that the metals are generally below the detection limit of the laboratory 

used to analyse the samples. 

The only variable that seems to be an issue is suspended solids. The 95 th percentile of 

suspended solids was reported to be 34 mg/ℓ at Bokong (compared to a median of 5 mg/ℓ) 

and 29.7 mg/ℓ at Kdamusurf. Nutrient levels for the monitoring points were also reported to 

be low. Ammonia is below 0.33 mg/ℓ, nitrates are below 0.5 mg/ℓ and phosphates are below 

0.23 mg/ℓ. 

The water quality assessment undertaken for the monitoring points indicates that Ec, 

chlorides, alkalinity and sulphates falls within an ideal category. Chemical Oxygen Demand 

(COD), iron, pH, ammonia fall in the acceptable category, while phosphates, silica and 

manganese fall within a tolerable level. The only variable that fell in an unacceptable 

category at various monitoring points was suspended solids for the 95 th percentile and some 

of the median for these monitoring points also fell in the unacceptable category. The reason 

for these high SS may be due to the rainstorm events which result in high loads of sediment 

transported to the receiving catchment. 

The impact assessment considered the assessment of the potential surface water impacts 

associated with the construction, operation and decommissioning phase of the construction 

of the new dam and the powerlines. 

The surface water quality may be impacted upon during the construction phase due to the 

following: 

• Clearing of vegetation, 

• Contamination of stor<strong>mw</strong>ater 

• Spillages of hydrocarbons/dangerous goods 

July 2012 v



• Discharging water found in the borrow pit and tunnel with high suspended solids, 

• Disposal of general waste, 

• Provision of insufficient sanitation. 

The impacts associated with the activities above are in general considered to be of a 

MEDIUM significance and will be mitigated to an impact with a LOW significance. The only 

impacts that were identified with a high significance were that of spillages of dangerous 

goods and the construction of river crossings. These will again be able to be mitigated to an 

impact with a LOW significance. 

During the operational phase water will be <strong>pumped</strong> from the Katse Dam to the Kobong Dam 

during periods when there is a low electricity demand. During periods of high electricity 

demand the water will be released from the upper reservoir to the lower Katse Dam to 

generate electricity. 

Impacts associated with the operational phase include: 

• Potential increase in salinity due to the evaporation of water in the upper reservoir, 

which may impact on the Katse Dam. The impacts associated with this are foreseen 

to be limited when the volume of water released from the Upper dam is compared 

with the volume of the Katse Dam. 

• The water quality in Katse dam has a low buffering capacity and is considered to be 

aggressive which may impact on equipment and concrete. The pH of the water may 

also decrease with the increase of depth and therefore it will be important to ensure 

that the water abstracted from the Katse Dam to be <strong>pumped</strong> to the Kobong upper 

reservoir is withdrawn from various levels. 

• The treated effluent generated from the sewage works will remain throughout the 

operational phase. The impact will be of a regional nature should the effluent be 

released which does not comply with the standards. Untreated or partially treated 

effluent may result in increase of nutrients. 

However the probability that this will happen is not likely due to the volume of effluent 

treated compared to the volume of water in the Katse Dam. The impact may be 

localised in the area where the water is released into the dam at the permanent 

labour camp. 

Mitigation measures were identified for each potential impact and should they be 

implemented it is considered that the significance of the impacts will be reduced. 

July 2012 vi



In conclusion it is not expected that the project will have a significant impact on the 

downstream catchment and Katse Dam due to the localised nature of the upper reservoir 

and the volumes of water that will be abstracted during the operational phase. 

July 2012 vii



LIST OF ABBREVIATIONS 

Cl Chloride 

CO3 2- Carbonate 

DWAF Department of Water Affairs and Forestry 

EC Electrical Conductivity 

EIA Environmental Impact Assessment 

EIS Environmental Impact Study 

HCO3 

Bicarbonate 

LEGA Lesotho Electricity Generation Authority 

LHDA Lesotho Highlands Development Authority 

LHWC Lesotho Highlands Water Commission 

NES National Environmental Secretariat 

NH3 

Ammonia 

NO2 

Nitrite 

NO3 

Nitrate 

OH - Hydroxide 

PO4 

Phosphate 

PPP Pumped Storage Scheme 

SS Suspended Solids 

LIST OF UNITS 

hrs Hours 

km Kilometres 

kV Kilovolts 

m Metres 

mm Millimetres 

mm/day millimetres per day 

m 3 

cubic metres 

MW Megawatt 

C⁰ degrees Celsius 

% Percentage 

July 2012 viii



1. INTRODUCTION 

July 2012 



1.1 BACKGROUND 

The Lesotho Highlands Water Commission (LHWC) has appointed ILISO Consulting 

(Pty) Ltd in association with Sechaba Consultants, to undertake an Environmental 

Impact Study (EIS) in compliance with the Lesotho Environment Act of 2008 for the 

proposed 1 <strong>000</strong> MW Kobong Pumped Storage Scheme. The purpose of the project is 

to develop infrastructure which will add to the reliable income already gained by the 

Kingdom of Lesotho via the Lesotho Highlands Water Scheme (LHWS), through the 

provision of both water and electricity. This is dominantly sold to South Africa for use 

in Gauteng as the economic and industrial centre of the greater sub-continental area, 

further, the greater LHWS <strong>scheme</strong> also provides the majority of Lesotho’s electricity. 

The provision of both water and electricity within Southern Africa are acknowledged 

to be significant long-term constraints to both economic development of the greater 

sub-region. For this reason, construction on the LHWS, with construction of the “kingpin” 

of the <strong>scheme</strong>, Katse Dam, began in the late 1980s as a joint partnership 

between Lesotho and South Africa. Katse Dam itself was completed in the late 

1990s. 

The aim of the LHWS is to supply both water and electricity in the form of 

hydroelectric power. The <strong>scheme</strong> is composed of a number of large dams, tunnels 

and associated electrical infrastructure. The dams are located in the highlands of 

Lesotho where water is relatively abundant and set at a high altitude which facilitates 

the hydro-electric power generation process. The project at hand is an extension of 

the existing LHWS as it will increase the overall electricity provision function, 

specifically for supplying additional electricity to South Africa. 

To meet this aim, a new <strong>pumped</strong> <strong>storage</strong> <strong>scheme</strong> is to be developed and linked to 

the Katse Dam Reservoir system in northern Lesotho. The project will consist of both 

water and electrical related infrastructure, with support structures as required. 

1-1



The specific purpose of this study is to consider the proposed underground 

1 <strong>000</strong> MW <strong>pumped</strong> <strong>storage</strong> <strong>scheme</strong> to be sited near Lejone on the Katse Dam 

Reservoir in northern Lesotho. 


A new 101 m high dam (i.e. the upper reservoir) on the Kobong River that has a 

Full Supply Level of approximately 2604 meters above sea level and is expected 

to inundate approximately 0.5 km 2 when full; 

An intake tower on the upper reservoir; 

A headrace tunnel (4 270 m, 11.5 m diameter, 12.1 % inclination), with 

penstocks and a surge arrestor; 

An underground 1 <strong>000</strong> MW power station; 

A tailrace tunnel (1 050 m long, 6.3 m diameter) and outlet tower at the Katse 

Dam (i.e. the lower reservoir); 

A 65 km long 400 kV transmission line from the powerhouse running north to 

Maputsoe near Lesotho’s border with South African – the power line will follow 

the existing feeder road from Kobong to the Katse intake, and from there it will 

run parallel to the existing transmission line; 

A switchyard near the Katse Dam; and, 

Construction specific infrastructure. 

1.2 PURPOSE OF THE EIA STUDY 

The objectives of the project are to fulfil the environmental assessment requirements 

necessary to: 

Provide the client (i.e. LHWC) with information pertaining to the sustainability of 

the project; 

Obtain environmental authorisation from the Kingdom of Lesotho National 

Environmental Secretariat (NES); and, 

Provide funding organisations with information they require to approve funding 

for the project. 

The specific purpose of the EIA study is to review the proposed project and to ensure 

that the aims given above are reached whilst still: 

Ensuring that all potential environmental effects are taken into account in terms 

of the planning and implementation (i.e. construction and operation) of the 

planned project; 

July 2012 1-2



Promote sustainable development; 

Ensuring that activities do not have a detrimental effect on the environment, 

including consideration of the biophysical and socio-economic factors; 

Facilitate public involvement; 

Provide the client with applicable information required to implement the project in 

an environmentally sound manner; 

Provide the information required to enable the NES to make informed decisions 

regarding the authorisation of the project; and, 

Provide funding donors with confidence that the project meets internationally 

acceptable environmental standards. 

1.3 PURPOSE OF THIS STUDY 

The Surface Water Quality Specialist Study will assess the assimilative capacity and 

fitness for use of the receiving stream and downstream users, including potential 

impacts on the Katse Dam. 

The issues with respect to water quality centre around two effects. The first is the 

<strong>storage</strong> of a large quantity of water in the proposed new dam, which can lead to 

eutrophic conditions and an increase in salinity due to the concentrating effect of 

evaporation losses. These problems tend to be accentuated during periods of 

prolonged low inflow. 

The second issue is a possible change in water quality in the river downstream of the 

new dam. The change can be far-reaching, such as a cumulative change in salinity 

as a result of reduced flows, or it can be of a local nature, such as changes in 

temperature directly downstream of the dam due to the release of colder bottom 

water. 

The effect of the proposed new dam on water quality will be studied as follows: 

• Obtain all available water quality data from existing data banks; 

• Determine from the data the current water quality as well as an assessment 

of the natural background conditions; 

• Predict the water quality in the dam by means of a mass balance; 

• Predict the changes in water quality downstream of the dam by analyzing a 

future predicted steady-state flow condition; 

July 2012 1-3



• Assess the fitness for use of the predicted water quality for the uses of the 

water that have been identified; and, 

• Propose mitigating measures where needed and appropriate. 

1.4 TERMS OF REFERENCE 

ILISO Consulting has been appointed by the LHWC to undertake the water quality 

assessment as part of the EIA in order to identify impacts of the proposed 

development on the water quality of the Katse Dam. 

1.5 AUTHOR’S CREDENTIALS AND DECLARATION OF INDEPENDENCE 

The author of this report, Dr M van Veelen of ILISO Consulting, is a professional 

engineer with a PhD in in Aquatic Health and has been involved in a variety of water 

quality studies. He was the project leader to develop water quality guidelines for 

domestic use in South Africa, and was responsible for the water quality study of the 

Olifants River (SA) as well as the water quality impact of the Zeekoegat and 

Baviaanspoort Waste Water Treatment Works near Tshwane in South Africa. He was 

also the water quality specialist for the proposed new Mosetse River Dam in 

Botswhana. 

He is a registered Professional Engineer (Reg. No. 800333), certified Environmental 

Assessment Practitioner and fellow of the South African Institution of Civil Engineers. 

He is a member of the South African Society of Aquatic Scientists, the International 

Water Association and the Water Institute of South Africa. Dr van Veelen has over 30 

years experience. Dr van Veelen is independent and has no vested interest in the 

proposed activity and will not engage in conflicting activities associated with the 

project. 

1.6 STRUCTURE OF THIS REPORT 

A description of the location of the project is provided in Chapter 2. A description of 

the approach and methodology is provided in Chapter 3 and the description of the 

environment in Chapter 4. The surface water quality status is provided in Chapter 5 

and the impact assessment is provided in Chapter 6. The mitigation measures are 

presented in Chapter 7. The conclusions and recommendations are presented in 

Chapter 8. 

July 2012 1-4



2. DESCRIPTION OF THE PROPOSED PROJECT 

July 2012 

The intention of this project is to enhance the existing Lesotho Highlands Water 

Scheme, so as to increase the electricity generation potential of the <strong>scheme</strong> as a 

whole. 

Due to high mountainous terrain on the western side of the existing Katse Reservoir, 

a potential head for a <strong>pumped</strong> <strong>storage</strong> <strong>scheme</strong> can be created between an upper 

reservoir and the water level of Katse itself as the lower reservoir as indicated in 

Figure. 

As a <strong>pumped</strong> <strong>storage</strong> <strong>scheme</strong> (PSS) does not consume water, with the same amount 

of water being transferred back and forth between the upper and lower reservoirs, 

the installed capacity of a <strong>pumped</strong> <strong>storage</strong> <strong>scheme</strong> can in principle be “unlimited”. 

A <strong>pumped</strong> <strong>storage</strong> <strong>scheme</strong> can be operated according to the demand of peak power 

and the availability of inexpensive off-peak power for the pumping mode. 

A <strong>pumped</strong> <strong>storage</strong> <strong>scheme</strong> thus takes advantage of the steep gradient characteristic 

of the Lesotho Highlands, combined with the availability of water, and space in which 

to build the infrastructure. 

The specific aim of the Kobong <strong>pumped</strong> <strong>storage</strong> system is to allow for the generation 

of additional electricity for sale to South Africa. 

2.1 DESCRIPTION OF THE PROPOSED INFRASTRUCTURE 


Reservoir (i.e. dam) and related infrastructure: 

o A new 101 m high dam (i.e. the upper reservoir) on the Kobong River – Katse 

Dam forms the lower reservoir; 

o An intake tower on the upper reservoir; 

o A headrace tunnel (4 270 m, 11.5 m diameter, 12.1 % inclination), with 

penstocks and a surge arrestor; 

o A tailrace tunnel (1 050 m long, 6.3 m diameter) and outlet tower at the Katse 

Dam (i.e. the lower reservoir); 

2-5



July 2012 

Figure 2-1: Description of the Kobong Pumped Storage Scheme 

2-6



July 2012 

Access roads: 

o A main access road to the construction area; and, 

o Temporary haul roads will be required in and around the dam wall. 

Electrical infrastructure: 

o An underground 1 <strong>000</strong> MW power station; 

o A 65 km long 400 kV transmission line from the powerhouse running north to 

Maputsoe near Lesotho’s border with South African – the power line will 

follow the existing feeder road from Kobong to the Katse intake, and from 

there it will run parallel to the existing transmission line; and, 

o A switchyard near the Upper Reservoir. 

Additional infrastructure on / near the site: 

o A temporary accommodation construction camp near to Kobong Village; 

o A permanent operation and maintenance building; 

o Staging areas for temporary <strong>storage</strong> and loading of parts and equipment; and, 

o Fencing (to be erected as required). 

Borrow pits / quarries: 

o A borrow pit will be located within the dam basin. 

A temporary construction camp will be built at the start of the construction phase. The 

site of the construction camp for the dam will be located downstream of the proposed 

dam wall. The construction camp will accommodate the following: 

Concrete Batching Plants; 

Site Offices and Parking; 

Workshops and Stores; 

Helipad; 

Weather Station; 

Sand and crushed stone Stockpile Areas; 

Areas for the handling of hazardous substances; 

An explosives <strong>storage</strong> magazine; 

Wash bays for construction plant; 

Radio communication infrastructure; 

Facilities for the bulk <strong>storage</strong> and dispensing of fuel for construction vehicles, 

A sewage treatment plant 

2-7



Power lines, a small-scale sewage treatment plant; and, 

A temporary solid waste disposal facility. 

The exact area to be inundated by the proposed new upper <strong>storage</strong> facility will 

depend on the final height of the dam, and is estimated to be approximately 0.5 km 2 . 

Table 2-1: Reservoir Area and Volume for Upper Dam Site 

Elevation 

Area 

m 

km 2 

Volume 

Million m 3 

2501 0.00 0.00 

2510 0.00 0.01 

2520 0.03 0.15 

2530 0.06 0.59 

2540 0.10 1.39 

2550 0.15 2.66 

2560 0.20 4.41 

2570 0.27 6.77 

2580 0.33 9.79 

2590 0.41 13.51 

2600 0.48 17.99 

2610 0.55 23.20 

2620 0.62 29.10 

2630 0.69 35.68 

2640 0.76 42.98 

2650 0.85 51.05 

2.2 DESCRIPTION OF THE PROPOSED DEVELOPMENT PROCESS 

In order to understand what is involved in the project, a summary is provided below 

of the construction process and sections that need to be constructed. As such, the 

project itself, should it be approved, will be implemented in a number of phases: 

Pre-construction phase: 

o This phase includes materials investigations, geological drilling, site 

surveying, mitigation of impacts on identified heritage resources, and, plant 

rescue. All of these tasks need to be carried out before construction activities 

commence. 

July 2012 2-8



Construction process: 

o The first task of the construction phase will be the development of the site 

construction camp for the dam, which will be just downstream of the 

proposed dam wall. 

o The main access road to the construction area will be constructed. Further, 

temporary haul roads will be required in and around the dam wall and a 

borrow pit will be located within the dam basin itself. 

o Construction procedure: 

Construction activities will commence with the stripping of vegetation 

and topsoil to establish the access and construction roads, site offices, 

dam foundations, and, crusher and concrete mixer stations. 

Excavators, bulldozers and trucks will be engaged to remove all loose 

material on the foundation area of the dam until sound founding material 

is exposed. Blasting will be necessary for this step. 

Sand will be required for the production of concrete and for filter 

construction. 

Concrete production at the batching plant will then commence and 

placement of the central spillway section, outlet works and apron areas, 

probably by roller compaction techniques and the use of high tower and 

mobile cranes, will occur 24 hours a day, seven days a week, for a 

period of time. Earth embankments will be constructed on both banks by 

compacting material hauled in by large trucks from the borrow areas 

upstream of the dam. 

The temporary site administrative buildings will be erected complete 

with security fencing, a water supply, a sewage purification plant and an 

electric overhead supply line. 

After construction activities have been completed all the crushers, 

mixers and site offices, etc., will be removed and the construction site 

rehabilitated. All temporary access roads not in the dam basin will be 

ripped and planted with suitable grass and tree cover. The aim is to 

return the whole construction site to as close as possible its 

undeveloped / pre-development appearance. 

The tunnel will be constructed by a process of drilling and blasting. 

July 2012 2-9



o Transmission line construction: 

A 55 m servitude (27.5 m on either side of the centre line) is required to 

accommodate the towers on which the overhead line will be strung. In 

forestry areas the servitude will need to be wider. The servitude is 

required to ensure safe construction, maintenance and operation of the 

line and the Lesotho Electricity Generation Authority (LEGA) will be 

entitled to unrestricted access. Where 400kV transmission powerlines 

are constructed in parallel, a minimum separation distance of 55 m 

between the centre points is required. The minimum vertical clearance 

between the line and the ground after construction is approximately 9 m. 

The land beneath the overhead lines can continue to be used for certain 

activities by the landowners. However, the height of structures and 

crops higher will be restricted along the route within the defined 

servitude. 

The co-ordinates of the centre line of the route and position of the 

towers will be determined by surveyors after a final route corridor has 

been approved by the environmental authorities. 

The construction process consists of the following phases: 

Contractor site establishment; 

Survey and pegging of tower positions; 

Access road negotiation and construction; 

Gate installation and vegetation clearing; 

Foundation excavation and installation; 

Tower assembly and erection; 

Conductor stringing and tensioning, and 

Servitude clean-up and rehabilitation. 

It is foreseen that there will be 2 construction camps required for the 

construction camps and the transmission powerline. They will be 

positioned at Kabong and one at Maputsoe. The exact position of these 

construction camps will be negotiated with the relevant landowners. 

Strict conditions, including the approval of the location of the 

construction camp and for the use and management of resources, will 

be set out in the Environmental Management Plan, and will have to be 

adhered to. 

Any plants that could interfere with the construction, maintenance or 

operation of the power line, will be removed or trimmed in accordance 

July 2012 2-10



with relevant legislation and the EMP. The EMP will specify standards to 

be adhered to for vegetation clearing and protected species 

management. Once the centre line has been cleared, the tower 

positions will be pegged. 

Vehicle access is usually required along the entire route for 

construction, maintenance and operation purposes. Existing roads will 

be used as far as possible and the construction of roads and bridges will 

be kept to the minimum. Any additional authorisation required will be a 

condition of the EMP and will be obtained during the implementation 

phase of the project and prior to the construction of the relevant 

component of the project. Gates will be installed on all fences that the 

line crosses. Any existing infrastructure will be maintained in (or 

returned to, if damaged) its existing condition. Access points and roads 

will be negotiated with the relevant landowners. 

The type of foundation required for each tower is dependent on the 

exact geo-technical conditions. The estimated working area required for 

the erection of a self-supporting strain tower is 40 m by 40 m, and for a 

cross-rope suspension tower is 50 m by 50 m. 

If the area is deemed non-sensitive grassland it will be trampled by 

activities, rather than cleared. 

Foundations may be drilled, mechanically excavated, or, dug by hand. 

No blasting will take place. Concrete is then placed in the footing area. 

Helicopters may be used to transport equipment and materials if tower 

positions are inaccessible. Due to the costs involved, this is not the 

standard method of accessing the towers and line and access roads will 

still be used for the majority of the route. 

Any incomplete excavations will be protected to prevent animals and 

people from injury until construction is completed. All foundations will be 

back-filled, stabilised through compaction, and, capped with concrete at 

ground level. Towers are lifted into position by cranes or helicopters, as 

appropriate. 

The conductor cable is then strung between towers by first passing a 

guide wire through the desired position. Cable drums, which contain 2.5 

km of cable and can be steel or wooden approximately 2.5 to 3 m in 

size, are placed at 5 km intervals in the cleared section of the servitude, 

July 2012 2-11



and fed out 2.5 km in each direction from the point of lay-down (i.e. the 

cable drum is placed at the centre point). 

o Operation: 

The principle behind the operation of a Pumped Storage System (PSS) 

is simple. Electricity costs more to produce and its availability is more 

limited, during peak-time periods (i.e. breakfast and dinner time, with a 

slightly lower peak across the remainder of the day). During off-peak 

time periods (i.e. late at night or in the very early morning) electricity is 

cheaper to use and is less limited in terms of availability. To take 

advantage of this situation, during peak-periods water is released in a 

controlled manner from the upper reservoir to the lower, using gravity, 

which turns the turbines of the power plant and thus generates 

electricity which is available to the power-grid. During off-peak periods, 

the water is <strong>pumped</strong> from the lower reservoir to the upper using cheaper 

and spare electrical capacity from the power-grid. The tunnel linking the 

2 reservoirs and the power plant are underground, thus limiting the 

footprint to the lower (i.e. existing Katse Dam) and the upper (i.e. 

proposed Kobong Dam) reservoirs, the electricity transfer mechanisms 

(i.e. sub-station and electricity transmission lines), and ancillary uses 

such as access roads and operational buildings. 

July 2012 2-12



3. METHODOLOGY 

July 2012 

The water quality assessment was conducted in two phases, water quality baseline 

characterisation and impact assessment. 

3.1 BASELINE CHARACTERISATION 

The objective of the baseline characterisation was to provide a description of the 

water quality that is found in the Katse Dam. Baseline water quality data obtained 

from the Monitoring & Evaluation Manager of the Lesotho Highlands Development 

Authority (LHDA) for the period from November 1996 to May 2012 was evaluated. 

3.2 IMPACT ASSESSMENT 

The impact assessment was conducted as described in the Scoping Report. This 

included a description of the nature of the impact, any specific legal requirements 

and the stage (i.e. construction, decommissioning, and, operation). Impacts were 

considered to be the same during construction and decommissioning. 

The following criteria were used to evaluate significance: 

Nature: The nature of the impact will be classified as positive or negative, and 

direct or indirect. 

Extent and location: Magnitude of the impact (see Table 3-1), and is classified 

as: 

o Local: the impacted area is only at the site – the actual extent of the activity; 

o Regional: the impacted area extends to the surrounding area, the 

immediate and the neighbouring properties; 

o National: the impact can be considered to be of National importance; and, 

o International: the impact can be considered to have an International impact, 

in this case, into South Africa. 

3-1



Table 3-1: Geographical extent of impact 

Category Extent Description 

A Local 

B Regional 

C National 

D International 

Impacted area limited to site – actual extent of 

activity. 

Impacted area extends into surrounding region 

/ area – including immediate and neighbouring 

properties. 

Impact considered of National importance – will 

affect entire country. 

Impact considered of International importance 

– crosses international borders. 

Duration: This measures the lifetime of the impact (see Table 3-2 below), and is 

classified as: 

o Short term: the impact will be for 0 – 3 years, or only last for the period of 

construction. 

o Medium term: three to ten years. 

o Long term: longer than 10 years or the impact will continue for the entire 

operational lifetime of the project. 

o Permanent: this applies to the impact that will remain after the operational 

lifetime of the project. This is defined as being permanent with mitigation 

feasible, or, is permanent without mitigation being possible. 

Table 3-2: Duration of Impact 

Category Duration Description 

A Short term 0 – 3 years, or length of construction period 

B Medium term 3 – 10 years 

C Long term > 10 years, or entire operational life of project. 

Mitigation measures of natural process will 

D Permanent – mitigated reduce impact – impact will remain after 

operational life of project. 

E 

Permanent – no 

mitigation 

No mitigation measures of natural process will 

reduce impact after implementation – impact will 

remain after operational life of project. 

July 2012 3-2



Intensity: This is the degree to which the project affects or changes the 

environment (see Table 3-3 below), and is classified as: 

o Low: the change is slight and often not noticeable, and the natural 

functioning of the environment is not affected. 

o Medium: The environment is remarkably altered, but still functions in a 

modified way. 

o High: Functioning of the affected environment is disturbed and can cease. 

Table 3-3: Intensity of Impact 

Category Intensity Description 

A Low 

B Medium 

C High 

Change is slight, often not noticeable, natural functioning 

of environment not affected. 

Environment remarkably altered, still functions, if in 

modified way. 

Affected environment function disturbed – potentially to 

ceasing to function. 

Probability: This is the likelihood or the chances that the impact will occur (see 

Table 3-4 below), and is classified as: 

o Low: during the normal operation of the project, no impacts are expected. 

o Medium: the impact is likely to occur if extra care is not taken to mitigate 

them. 

o High: the environment will be affected irrespectively; in some cases such 

impact can be reduced. 

Table 3-4: Probability of Impact 

Category Probability Description 

A Low During normal operation, no impacts expected. 

B Medium Impact is likely to occur IF mitigation is not carried out. 

C High 

Environment will be affected irrespective of action, 

mitigation may reduce impact. 

Confidence: This is the level knowledge or information available, the 

environmental impact practitioner or a specialist had in his/her judgement (see 

Table 3-5 below), and is rated as: 

o Low: the judgement is based on intuition and not on knowledge or 

information. 

July 2012 3-3



o Medium: common sense and general knowledge informs the decision. 

o High: Scientific and or proven information has been used to give such a 

judgement. 

Table 3-5: Confidence in level of knowledge or information 

Category Confidence Description 

A Low 

Judgement 

information. 

based on intuition, not knowledge / 

B Medium Common sense and general knowledge informs decision. 

C High Scientific / proven information informs decision. 

Significance: Based on the above criteria the significance of issues will be 

determined. This is the importance of the impact in terms of physical extent and 

time scale, and is rated as (see Table 3-6 below): 

o Low: the impacts are less important, and will require no mitigation actions. 

o Medium: the impacts are important and require attention; mitigation is 

required to reduce the negative impacts to acceptable levels. 

o High: the impacts are of great importance. Mitigation is therefore crucial. 

Table 3-6: Significance of issues (based on parameters) 

Category Confidence Description 

A Low 

Impacts are less important, not deemed to need 

mitigation. 

B Medium 

Impacts are important, require action, mitigation required 

to reduce negative impacts to acceptable levels. 

C High Impacts of great importance, mitigation is crucial. 

Cumulative Impacts: The possible cumulative impacts will also be considered. 

Mitigation: Mitigation for significant issues will be incorporated into the 

Environmental Management and Mitigation Plan (EMP) for construction. 

3.3 MITIGATION MEASURES 

Mitigation measures to minimise or avoid the identified negative impacts on the 

receiving water environment were included as part of the report. 

July 2012 3-4



4. DESCRIPTION OF THE RECEIVING ENVIRONMENT 

July 2012 

This section will provide a general description of the upper catchment that will be 

affected near Ha Lejone and the Katse Reservoir where the Kobong Pumped 

Storage Scheme will be constructed 

4.1 LOCATION OF ACTIVITY 

The proposed site occurs in the northern part of the Kingdom of Lesotho. More 

specifically it is located near Ha Lejone and the Katse Reservoir. The site falls within 

the administrative jurisdiction of the Leribe District Council. 

The site is in a quiet, low population density area, characterised by rural agricultural 

activities along with a small village, with minimal traffic moving either into or through 

the area. 

The transmission power line will run from the Katse Reservoir area, adjacent to the 

existing power line, to Maputsoe located close to the border with South Africa. 

Figure 4-1 and Figure 4-2 indicate the proposed project area and layout. 

4-1



Figure 4-1: The general location of the Kobong Pumped Storage Scheme 

July 2012 4-2

29°10'0"S 

29°11'0"S 

29°12'0"S 

29°13'0"S 

29°14'0"S 

2900 

$ 

2900 

2800 

28°25'0"E 

2800 

2900 

INTAKE 

28°25'0"E 

ROCK QUARRY 

HEADRACE TUNNEL 

SPILLWAY 

KOBONG 

UPPER RESERVOIR 

FSL 2604 

2400 

2700 

2800 

SURGE SHAFT 

A 

CONSTRUCTION YARD AND 

CRUSHING AND BATCHING PLANTS 

AREA 200 <strong>000</strong> m 3 

2800 

2900 

28°26'0"E 

28°26'0"E 

2800 

POWER HOUSE 

2700 

NEW ACCESS ROAD 

2600 

Ha Rafanyane Khohlong 

! 

2500 

28°27'0"E 

MAIN ACCESS TUNNEL 

Ha Rafanyane Sehaula 

! 

2200 

28°27'0"E 

Ha Rafanyane Matsoapong 

! 

TAILRACE TUNNEL 

2200 

ADIT 

RAFANYANE BRIDGE 

Ha Thoora Ha Mokomane 

! 

Ha Thoora Ha Mofota 

! 

Ha Ts'Ehlo 

! 

! 

2400 

2300 

Ha Thoora Ha Tlali 

! 

2200 

2200 

2100 

2200 

Ha Thoora Ha Mallane Ha Mamokiba 

! 

2200 

2100 

2100 

Ha Rafanyane Matsoiring 

! 

EXISTING FEEDER ROAD 

2100 

2100 

28°28'0"E 

28°28'0"E 

Ha Sekhele Moreneng 

! 

Ha Sekhele Matebeleng 

! 

Ha Rafanyane 

! 

Kobong Ha Nkone 

! 

! 

! 

! 

Ha Thibeli Khohlong 

! 

Ha Thibeli Lithakong 

! 

2100 

OUTLET 

CONSTRUCTION YARD 

AREA 250 <strong>000</strong>m 3 

! 

Ha Thibeli 

! 

Ha Rafanyane Thoteng 

! 


2200 

2100 

2100 

2100 

2100 

2100 

28°29'0"E 

2100 

MAIN ROAD TO KATSE 

NEW 

ACCESS 

ROAD 

SWITCH YARD 


28°29'0"E 

2100 

2100 


Mphorosane 

! 

OFFICE 

MANAGEMENT 

AREA 75 <strong>000</strong>m 3 + 75 <strong>000</strong>m 3 

CONSTRUCTION YARD 


2100 

2100 

2200 

2100 

2100 

Ha Nts'Eli Kutu-Kutu 

! 

Ha Nts'Eli Patising 

! 

2200 

LABOUR CAMP 


Mphorosane Moqoboko 

! 

2100 

2200 

28°30'0"E 

2200 

! 

Ha Selei 

Ha 'Mikia Moreneng 

! 

Mphorosane Makaoteng 

! 

28°30'0"E 

EXISTING FEEDER ROAD 

Mphorosane Ha Tema 

! 

Mphorosane Thepung 

! 

0 0.5 1 2 Km 

! 

28°31'0"E 

Litjokofeng 

! 

Ha Bereng Qophello 

! 

PLAN OF 

ALTERNATIVE 1 

Ha 'Mikia Ha Moakhi 

! 

Ha 'Mikia Nts'Irele 

! 

Laitsoka Majakaneng 

! 

Laitsoka 

! 

Laitsoka Nts'Irele 

! 

Ha Bereng Mafikeng 

! 

Ha Bereng ! 

! 

Ha Bereng Khohlo-Nts'O 

1:15<strong>000</strong>(A1) 

FIGURE 28°31'0"E 2:1 

Ha Bereng Taung 

! 

REV. NO. DESCRIPTION 

DATE SIGN 

KOBONG Ha Bereng Lekhaloaneng 

! 

PUMPED STORAGE SCHEME 

SWECO 

SWECO International 

Gjörwellsgatan 22, Box 34044, 10026 Stockholm, Sweden 

Phone +46 8 695 60 00, Fax +46 8 695 60 10 

REG. NR. 

SCALE 

DRAWN/DESIGNED 

FIGURE NO. 

ADMINISTRATOR CHECKED 

5463586 KNLU AGUS HNMA 

DATE 

2010-12-22 

SWECO APPROVAL 

Göran Lifwenborg 

REV. 

29°10'0"S 

29°11'0"S 

29°12'0"S 

29°13'0"S 

29°14'0"S



Air Survey 

Kobong Site 

Katse Dam 

Katse Lodge 

Road Survey 

Figure 4-3: Proposed Transmission Line Route as surveyed by helicopter 

The proposed upper <strong>storage</strong> reservoir is located on an unnamed tributary forming 

part of the Kobong River system that flows through a remote and mountainous area. 

Upstream of the dam site the only land use that occurs is livestock grazing. 

Downstream of this point the river joins the other tributaries forming the Kobong River 

which flows into the Katse dam approximately 4 kilometres downstream. 

The closest village is Ha Lejone. 

Figure 4-4 presents pictures of the greater site showing its characteristics. 

July 2012 4-4



A. Kobong Dam basin B. View from the proposed adjunct down to proposed 

tunnel start point 

C. Herding posts affected by the dam reservoir and 

electricity transmission line 

E. Bokong Nature Reserve – parts of which the 

electricity transmission line will run 

D. Bokong Nature Reserve – parts of which the 

electricity transmission line will run 

F. Electricity transmission line will go down this valley, 

the run along the plain below 

July 2012 4-5



G. Katse Dam H. Kobong Village 

I. Kobong River J. Proposed site for the construction accommodation 

camp site 

K. The road along which the first part of the 

transmission line will run 

L. Mountainous area through which the electricity 

transmission line will run 

July 2012 4-6



K. Upper section of the lowlands which is traversed by 

the electricity transmission line 

M. Maputsoe – the end point of the electricity 

transmission line 

O. Typical lowland land-use types 

Figure 4-4: Photographic overview of the greater site 

L. Housing type in the areas through which the 

electricity transmission line will run that may 

require compensation measures 

N. An example of an electrical sub-station that will 

form part of the PSS 

Q. An example of the watercourse which the 

transmission line will need to cross 

July 2012 4-7



4.2 LANDSCAPE AND LANDUSE 

4.2.1 Access Routes 

Figure 4-5: Mafika-lisiu Pass through the Lesotho Highlands 

The A25 is the main tarred access road running from Leribe to the Katse Information Centre. 

Minor local access roads run along the western edge of the Malibamatso River from the A25 

to the villages of Kobong and Ha Thoora. 

July 2012 4-8



4.2.2 Nature and Conservation 

Figure 4-6: View of Bokong Nature Reserve 

4.2.3 Agriculture 

Figure 4-7: Agricultural land 

15 km to the north of the proposed dam is 

the 1 970 hectare Bokong Nature Reserve 

at the head of the Mafika-lisiu pass. 

Bokong Nature Reserve and the 

Liphofung Cave Cultural Historical Site 

are administered by Lesotho Northern 

Parks. They were originally established 

by the LHDA to compensate for the loss 

of biodiversity caused by the Lesotho 

Highlands Water Project. The affected 

communities have benefited through 

tourism projects in these areas (Wade 

Publications 2011. Lesotho Economic 

Review). 1 

Agriculture is a major source of 

employment within the country and is 

dominated by livestock activities. 

However, arable land is reported to have 

fallen from 13 percent of the total area at 

Independence (in 1966) to 9 percent due 

to residential encroachment, one of the 

most severe causes of soil erosion on the 

continent (Ministry of Economic Planning, 

1989). 

July 2012 4-9



4.2.4 Construction Industry 

Figure 4-8: View of surrounding infrastructure 

4.2.5 Recreation and Tourism 

Figure 4-9: Tourist accommodation at Bokong 

Nature Reserve 

The construction sector has been an 

important contributor to Lesotho’s Gross 

Domestic Product. Water is sold to South 

Africa under the authority of the Lesotho 

Highlands Development Authority. The 

development of the Lesotho Highlands 

Water Project in 1986 involved the 

construction of a system of dams and 

tunnels to transfer water from Lesotho to 

South Africa’s Vaal Dam, as well as the 

building of roads and the generation of 

hydro-electricity for use in Lesotho. 

Completed in 2004, the first phase 

comprised the 185 m high concrete 

double-curvature Katse Dam (the highest 

in Africa) and the 145 m high concretefaced 

rockfill Mohale Dam, their 

interconnecting tunnels and the ‘Muela 

Hydropower Station. 2 

Existing identified tourist attractions in the 

area include the Katse Dam, the Bokong 

Nature Reserve, Lepaqoa Valley and 

Waterfall, and Orion Katse Lodge. The 

Lesotho Vision 2020 highlights the need 

to conserve the scenery of the Lesotho 

Highlands and the unique ecosystem of 

the country for future potential tourism 

opportunities. 

2 Wade Publications 2011. Lesotho Economic Review. http://www.lesothoreview.com/construction.htm 

July 2012 4-10



4.2.6 Residential 

Figure 4-10: Local Village residential dwellings 

The closest villages to the proposed Dam 

are Kobong (3.7 km), Ha Thoora (3.5 km) 

and Ha Rafanyane (5 km) (distances are 

measured to the proposed dam wall). 

4.3 TOPOGRAPHY AND GEOLOGY 

The National University of Lesotho Rangelands Preliminary Report, 1998 3 , states 

that the terrain in Lesotho is mostly highland with plateaus, hills and mountains, with 

the lowest point at the junction of the Orange and Makhaleng Rivers, and Mount 

Thabana Ntlenyana being the highest point at 3 482 m. The country is divided into 

four physiographic regions: The Lowlands form a narrow strip along the western 

border with South Africa at approximately 1 500 to 1 800 m above sea level; the 

Foothills range in elevation from 1 800 to 2 <strong>000</strong> m above sea level along the lower 

mountain range; the Senqu River Valley is a major grassland area marked by shallow 

soils; and the Mountain region ranges from 2 <strong>000</strong> to 3 400 m above sea level. The 

last mentioned area is primarily used for summer grazing and hosts some unique 

alpine and sub-alpine habitats of the Drakensburg range. 

The aquatic study undertaken by SAS (2012) determines that the area is almost 

entirely underlain by basaltic lava flows of the Drakensberg Group, with some of the 

shallow soils covering sandstones of the Clarens formation (Stormberg Group, Karoo 

Supergroup) in the form of disintegrating carpets. Soils derived from the basalt have 

fairly even proportions of coarse sand, fine sand, silt, clay, and organic matter. The 

organic matter increases from about 20 % on the slopes to about 26 % in the valleys. 

The high organic contend results in a high water-retention capacity of the soil. Water 

redistribution through seeps is frequent (Mucina & Rutherford, 2006). 

3 

Global Change and Subsistence Rangelands in Southern Africa: Resource Variability, Access and 

Use in Relation to Rural Livelihoods and Welfare A Preliminary Report and Literature Review for 

Lesotho. Contributors: Makoala Marake, Chaba Mokuku, Moeketsi Majoro, None Mokitimi. National 

University of Lesotho. 1998. http://rangeland.bangor.ac.uk//reports/le-task0.htm#Bioph 

July 2012 4-11



Figure 4-11: Sense of Place showing view of Maluti Mountains 

According to the tourist information website www.seelesotho.com, the geology of the 

greater Lesotho area is a high mountain plateau, carved out by river valleys. Most of 

these rivers drain into the Senqu River, which later becomes one of South Africa's 

major rivers, the Orange. The river valleys and the mountain ranges run from the 

north-east to the south-west of the country. The area between the Caledon River 

and the first range of mountains is known as the Lowlands. The peaks and ridges of 

the mountains are harder basalt and have therefore resisted erosion. The basalt 

layers in the Lowlands have eroded and exposed the sandstone. 4 

4.4 CLIMATE 

The site experiences temperatures characteristic of its relatively high altitude giving it 

a warm, but not hot, summer, while winters are cold, often with snow. Rainfall is year 

long, but is dominantly during summer. Rainfall, or precipitation as snow, does occur, 

as is characteristic of the high Drakensberg area, and is higher than the surrounding 

lowlands of both Lesotho and South Africa. Rainfall events can be very extreme, 

given that over 40 % of the annual rainfall falls within a 3 month period (i.e. 

November to January). The combination of a cool to warm rainy season, and the dry 

season being during the coldest months is likely to lead to lower evaporation indices. 

4 http://www.seelesotho.com/About-Lesotho/General-Information/Geography.html 

July 2012 4-12



Table 4-1:Temperature characteristics for Kobong site (approx. location; 

altitude 2 300 m): Key: Temp. = Temperature 

Month 

Temperature 

(°C) 

Min. Max. 

January 9 22 

February 8.7 21.4 

March 7.1 19.7 

April 3.7 17 

May 0.1 13.7 

June - 3 11.3 

July - 2.7 11.5 

August - 0.2 13.2 

September 3 16.5 

October 5.3 18.6 

November 6.7 19.9 

December 8.2 21.2 

Yearly average (min / max) 3.8 17.2 

Annual mean temp. 10.5 

Max temp. of warmest month 22.0 

Min temp. of coldest month - 3.0 

Temp. annual range (A) 25.0 

Mean monthly temp. range (B) 13.3 

Mean temp. of wettest quarter 14.5 

Mean temp. of driest quarter 5.0 

Mean temp. of warmest 

quarter 

15.1 

Mean temp. of coldest quarter 5.0 

Isothermality (B/A*100) 53.4 % 

Temp. seasonality (STD * 100) (414.3) 

(Data: www.worldclim.org) 

July 2012 4-13



Table 4-2: Precipitation characteristics for Kobong site (approx. location; 

altitude 2 300 m): Key: Precip. = Precipitation 

Month 

Precipitation (mm) 

Average 

January 116 

February 98 

March 89 

April 50 

May 27 

June 12 

July 12 

August 22 

September 43 

October 88 

November 102 

December 107 

Annual precipitation 766 

Precip. of Wettest Month 116 

Precip. of Driest Month 12 

Precip. Seasonality (CV) 62.5 

Precip. of Wettest Quarter 325 

Precip. of Driest Quarter 46 

Precip. of Warmest Quarter 321 

Precip. of Coldest Quarter 46 

(Data: www.worldclim.org) 

4.5 VEGETATION AND BIODIVERSITY 

Lesotho is generally considered to be a grassland biome with a limited forest cover. 

Afro Mountain Grassland covers approximately 52% of the country, followed by Moist 

Cold Highveld Grassland at 22% and Alti Mountain Grassland at 24% (Lowe and 

Robelo, 1996). The sub-alpine scrub occurs at elevations above 2 <strong>000</strong>m above sea 

level. The alpine belt occurs above the sub-alpine scrub at 2 800m above sea level. 

The Maluti/ Drakensberg alpine region contains unique habitats including bogs, fans 

and afro-alpine wetland sponges with high levels of endemic plants. 5 

5 Global Change and Subsistence Rangelands in Southern Africa: 

http://rangeland.bangor.ac.uk//reports/le-task0.htm#Bioph 

July 2012 4-14



Figure 4-12: Site of proposed Kobong Dam showing existing vegetation 

Katse Dam, Bokong Nature Reserve and the A25 road all have significant landscape 

character which is associated with tourism. As such, it will be important to ensure 

that project components located in areas which are associated with tourist scenic 

views do not detract from the sense of place. 

The Kobong Dam site falls within the Grassland biome (i.e. a large area 

characterised by broad ecological patterns), and specifically falls within the 

Drakensberg Grassland Bioregion. More specifically, the site falls within the 

Themeda-Festuca Alpine Veld and/or Lesotho Highland Basalt Grassland vegetation 

type which has a characteristic suite of species. The Lesotho Highland Basalt 

Grassland’ vegetation type has a vast range within the sub-continent, and is related 

in the main to altitudes between about 1 900 – 2 900 m. This upland heath vegetation 

may include sensitive and/or Red Data List plant and animal species. 

The vegetation is currently less impacted on by human activities close to the Kobong 

dam basin due to the high altitude and related weather conditions. Closer to the 

Kobong Village and Katse Dam, the area is more significantly modified with related 

changes to the vegetation and remainder of the ecosystem. 

An important sub-category of the ecology of the greater site is that of the 

watercourse, its tributaries, their associated wetland areas and the Katse Dam. 

4.6 SOCIO-ECONOMIC STATUS 

Directly affected communities are regarded as those who are located near the project 

components and associated infrastructure such as construction camps, lay down 

areas, and, borrow pits. The following broad communities have been identified: 

Project area village communities located within close proximity to the project 

area and at the start of the power line, i.e. Mphorosane, Ha Rafanyane Thoteng, 

Ha Sekhele Matebeleng, Ha Sekhele Moreneng, Ha Rafanyane Sehaula, Ha 

Rafanyane Khohlong, Ha Rafanyane Matsoapong, Kobong Ha Nkone, Ha 

July 2012 4-15



Thoora Ha Mokomane, Ha Thoora Ha Mofota, Ha Thoora Ha Tlali, and Ha 

Thoora Ha Mallane Ha Mamokiba amongst others; 

Neighbouring villages located in the Katse Reservoir catchment; 

Ha Lejone residents, being the wider city community that will experience both the 

construction impacts (such as increased traffic) and operation impacts; 

Villages and towns located along the power line route to Maputsoe; and, 

The nation, being all citizens of the country who stand to benefit from the 

improved health services associated with the project. 

Communities living in the area adjacent to the power line may be affected by the 

construction and placement of the power line and associated pylons. 

Potential negative impacts resulting from the project include the spread of HIV and 

AIDS in the immediate area of the construction camp, and the impacts of blasting on 

nearby communities in terms of safety and damage to existing structures. 

The high levels of poverty in Lesotho are closely associated with the HIV and AIDS 

pandemic which has emerged as the worst humanitarian crisis that Lesotho has had 

to endure in recent times. The incidence of HIV and AIDS in Lesotho is now 

reportedly one of the highest in Southern Africa at a prevalence rate of 24 % among 

all adults in the 14 – 49 year range. The rate in urban areas is 29 %, while that in 

rural areas is 22%. The rate among women is 26 %, while that among men is 19 %. 

AIDS also appears to be most pronounced in young women (15 – 29), who account 

for 75 % of all reported cases. This is attributed to the so-called ‘sugar-daddy’ 

phenomenon of older men having sex with younger women. 

The debilitating effects of HIV and AIDS have made it virtually impossible for people 

to contribute productively to the livelihoods of their households. It has decimated 

entire families, leading to the liquidation of family assets or resources being diverted 

from everyday household requirements as these are used to care for the sick or offset 

medical and/or burial costs, children are dropping out of school because they 

have to nurse their sick parents or work in order to feed their younger siblings, and so 

forth. 

The increasing number of HIV and AIDS orphans and vulnerable children is a 

constant reminder of the havoc brought about by the pandemic. Various estimates of 

the population of orphans have been suggested. For instance, Kimane (2006) cites 

92 <strong>000</strong> from a 2004 survey, and 181 <strong>000</strong> by USAID, UNICEF and UNAIDS (2004), a 

figure projected to rise to 210 <strong>000</strong> by 2010 6 . Regardless of the exact figure, it is 

evident that Lesotho is facing the reality of having a very large proportion of its 

children living without parents. 

6 

This summary of the HIV/AIDS is drawn largely from R. Leduka and J.Gay, Lesotho Country Social 

Assessment: Literature Review, Sechaba Consultants for the World Bank, 2007 

July 2012 4-16



The recently released 2006 Census results have confirmed that HIV and AIDS 

(together with declining fertility rates and out migration) have severely constrained 

growth, reducing it to virtually zero. This is unlikely to change within the next 

generation (30 years) as the child bearing population is most directly impacted. The 

growth rates between census years are shown in the graph below: 

Source: BOS, 2008 

Figure 4-13: Population Growth Rates: 1976 to 2006 

Due to its cold climate Lesotho is fortunate not to have any of the major tropical 

waterborne diseases, such as bilharzia (Schistosomiasis), river blindness 

(Onchocerciasis), or, Guinea worm (Dracunculiasis). Diseases, such as typhoid and 

cholera, do exist but are not common. By contrast, diarrhoea is common. If left 

untreated, diarrhoea presents a serious risk to children, particularly for those under 

five years of age. 

July 2012 4-17



5. SURFACE WATER QUALITY STATUS 

The study area is located in the upper reaches of the Kobong River catchment where 

the proposed Kobong Dam will be developed as part of the proposed <strong>pumped</strong> 

<strong>storage</strong> <strong>scheme</strong>. This Dam will form the upper reservoir and the Katse Dam will form 

the lower reservoir. 

The aquatic ecosystems (i.e. watercourse and related wetland areas) specific to the 

proposed project are the Kobong River and associated tributaries which lead into the 

Katse Dam. 

The area is characterised by a low population density. Nonetheless, the area and its 

watercourses have been modified by human intervention (e.g. herd access to the 

water, fields, erosion / siltation from residential areas up-slope). The wider area has 

also been significantly altered in the last 3 decades by the presence of the Katse 

Dam Reservoir with its implications on the water network of the area. 

5.1 AVAILABILITY OF DATA 

No water quality data was available for the Kobong River especially in the upper 

reaches. The upper catchment where the dam will be located have a very limited 

catchment. The upper reaches of the Kobong River is directly dependent on rainfall 

and melting snow after winter. It is expected that the upper reaches will be dry 

during some parts of the year if not most parts. 

Water quality data for the Katse Dam was obtained from the Monitoring & Evaluation 

Manager of the Lesotho Highlands Development Authority for the monitoring points 

indicated in Table 5-1 and Figure 5-1. This study will evaluate the impact of the 

project during the construction phase on the tributaries and the long term impact on 

the Katse Dam. . 

Table 5-1: Lesotho Highlands Development Authority water quality monitoring 

stations in the Katse Dam 

Monitoring Point 

Name 

Located on feature name Latitude/ 

Longitude 

Period samples 

taken 

Bokong Not available 23/05/1996 - 

05/09/2012 

Kda<strong>mw</strong>surf Katse Dam wall surface S 29 20.212; 

E 28 28.981 

Kdamisurf Katse Dam Island surface S29 14.720; 

E28 28.792 

Kdamusurf Katse Dam Upstream surface S29 05.883 

E28 30.300 

Kdamtsurf Katse Dam Tower (intake) 

surface 

S29 10.353 

E28 28.981 

23/05/1996 

-05/09/2012 

23/05/1996 

-05/09/2012 

21/11/96 

-05/09/2012 

23/05/96 

-05/09/2012 

July 2012 5-18



Figure 5-1: Locality of the monitoring points 

July 2012 5-19



5.2 VARIABLES OF CONCERN 

All the variables received from the Lesotho Highlands Development Authority were 

not assessed but only the variables that were expected to have an impact on the 

Pumped Storage Scheme or which could be expected to be impacted on during the 

construction or operational phase of the project were compared with the DWAF 

Water Quality Guidelines (2006) for the relevant water users. 

The following indicator variables were assessed. 

Temperature 

Temperature may be defined as the condition of a body that determines the transfer 

of heat to, or from, other bodies. As temperature increases viscosity, surface 

tension, compressibility, specific heat, the ionisation constant and the latent heat of 

vaporisation decrease whereas thermal conductivity and vapour pressure increase 

(DWAF 2006). 

The Water Quality Guidelines explains that temperature plays an important role in 

water by affecting the rates of chemical reactions and therefore also the metabolic 

rates of organisms. Temperature is therefore the most important factor controlling 

the distribution of aquatic organisms. Natural variations in water temperature occur 

in response to seasonal and diel cycles and organisms use these changes as cues 

for activities such as migration, emergence and spawning. Artificially – induced 

changes in water temperature can thus impact on individual organisms and on entire 

aquatic communities. 

pH 

The pH of natural waters is a measure of the acid-base equilibrium of various 

dissolved compounds, and is a result of the carbon dioxide-bicarbonate-carbonate 

equilibrium which involves various constituent equilibriums, all of which are affected 

by temperature. Conditions which favour production of hydrogen ions result in a 

lowering of pH, referred to as an acidification process. Alternatively, conditions which 

favour neutralisation of hydrogen ions result in an increase in pH, referred to as an 

alkalinisation process. The pH of water does not have direct consequences on the 

use except at extremes. The adverse effects of pH result from the solubilisation of 

toxic heavy metals and the protonation or deprotonation of other ions (DWAF: 

Ecosystems, 1996). pH is used as an indicator of characteristics such as the acidity 

or alkalinity of the water, which in turn is an indication of possible aggressive or 

corrosive properties. Health impacts are normally limited to irritation of mucous 

membranes or the eyes when swimming. The aquatic ecosystem is only affected by 

significant deviations from the natural background value. 

July 2012 5-20



Alkalinity 

Alkalinity is the measure of the acid-neutralising capacity of water. Ions which 

commonly contribute to the alkalinity of water are bicarbonate (HCO3 - ) and carbonate 

(CO3 -2 ) and at a high pH hydroxide (OH - ). The geological nature of rocks and soils 

in a particular catchment might determine the alkaline content of the water. Elevated 

concentrations of alkalinity can lead to various problems: 

Elevated concentrations of alkalinity and hardness are conducive to scaling 

and may result in the damage of equipment and structures. 

It can further influence process as it may promote precipitation of calcium 

carbonate especially in hard water or in alkaline processes. 

It can influence product quality. 

The treatment of water to remove alkalinity may result in increased levels of 

TDS or chlorides which may require special treatment prior to discharging the 

effluent. 

Total Dissolved Solids (TDS)/ Electrical Conductivity (EC) 

The total dissolved solids (TDS) are a measure of the quantity of various inorganic 

salts dissolved in water. The TDS concentration is directly proportional to the 

electrical conductivity (EC) of water. Normally at a ratio of TDS: EC of 6.5:1. Since 

EC is much easier to measure than TDS, it is routinely used as an estimate of the 

TDS concentration (DWAF: Domestic, 1996). Electrical Conductivity (EC): is used as 

an indicator of the salinity of the water. This affects industrial and domestic use as 

well as irrigation. The aquatic ecosystem is only affected if the salinity deviates to a 

large extent from the natural background value. 

Suspended Solids (SS) 

Suspended solids in water consist of inorganic and organic matters such as, clay 

particles or suspended mineral matter and a combination of decay products and 

living organisms respectively. In clear non turbid waters, like spring water, the 

suspended matter is low or absent, while in muddy waters, the amount of suspended 

matter is high (DWA: Industrial, 1996). The amount of suspended matter found in the 

rivers draining a catchment is usually an indication of the soil erosion that occurs. 

The presence of suspended solids in water supplies is one of the main causes of 

fouling. Fouling is the accumulation of inorganic and organic solid matter other than 

scale, which interferes with the normal operation of a facility and may contribute to 

deterioration and is encountered in steam generation and cooling water systems 

where it causes blockages, impedes the air circulation and can lead to localised 

overheating in boilers with subsequent metal damage. It can further be abrasive and 

cause failure of pump seals, bearings or valves. 

July 2012 5-21



Nitrite (NO2)/Nitrate (NO3) 

Nitrogen refers to all inorganic nitrogen forms present in water, that is, ammonia, 

ammonium, nitrite and nitrate. Ammonia (NH3) and Ammonium (NH4) are the 

reduced forms of inorganic nitrogen and their relative portions in water are governed 

by water temperature and pH. Nitrite (NO2) is the inorganic intermediate and nitrate 

(NO3) the end product of the oxidation of organic nitrogen and ammonia. Nitrate is 

the more stable of the two forms, and usually, by far, the more abundant in the soil 

and water environment. In view of their co-occurrence and rapid interconversion, 

nitrite and nitrate are usually measured and considered together (DWAF: Irrigation, 

1996). Nitrate/Nitrite (NO3/NO2): has a health effect on humans, and is also an 

indication of contamination from human activities in the catchment, notably the 

discharge of treated waste water. Nitrite has a toxic effect on aquatic organisms, 

particularly those organisms that breathe under water. 

Ammonia (NH3) 

Total Ammonia is used as an indicator of the presence of Ammonia which is highly 

toxic to aquatic life even in low concentrations, and is therefore difficult to measure. 

Ammonia has no effect on human consumption or on irrigation in the concentrations 

in which it occurs in rivers and streams. Ammonia is broken down to Nitrate/Nitrite 

by bacteria that occur naturally in water bodies. 

Phosphate (PO4) 

Phosphorus can occur in numerous organic and inorganic forms, and may be present 

in waters as dissolved and particulate species. Elemental phosphorus does not 

occur in the natural environment. In unimpacted waters Phosphorus is readily 

utilized by plants and converted into cell structures by photosynthetic action. 

Phosphorus is considered to be the principle nutrient controlling the degree of 

eutrophication in aquatic ecosystems. Natural sources of phosphorus include the 

weathering of rocks and the subsequent leaching of phosphate salts into surface 

waters, in addition to the decomposition of organic matter. In South Africa, 

phosphorus is seldom present in high concentrations in unimpacted surface waters 

because it is actively taken up by plants. Elevated levels of phosphorus may result 

from point-source discharges such as domestic and industrial effluents, and from 

diffuse sources (non-point sources) in which the phosphorus load is generated by 

surface and subsurface drainage. Non-point sources include atmospheric 

precipitation, urban runoff, and drainage from agricultural land, in particular from land 

on which fertilizers have been applied. 

Phosphorus concentrations are usually determined as orthophosphates, total 

inorganic phosphate or total dissolved phosphorus (which includes organically bound 

phosphorus and all phosphates). The dissolved forms are measured after filtering 

the sample through a pre-washed 0.45 μm filter. Concentrations of particulate 

phosphorus can be calculated from the difference between the concentrations of the 

total and dissolved fractions (DWAF: Ecosystems, 1996). Phosphate (PO4): has no 

July 2012 5-22



direct effect on the use of water, but is an indicator of contamination from activities in 

the catchment such as waste water discharge and fertilisers from agricultural 

activities 

Chloride 

Chloride is the anion of the element chlorine. Chlorides of sodium, potassium, 

calcium and magnesium are highly soluble in water and tend to accumulate. 

Chlorides cannot be removed through precipitation at concentrations normally 

present. Electrolysis is used to remove the chloride to form chlorine gas but is not 

effective when the Cl and Ec are low. High concentrations of Chlorides can result in 

damage to equipment and are specifically aggressive to stainless steel, causing 

localised stress and cracking corrosion (DWAF: Industrial, 1996). 

Sulphate 

Sulphate is a common constituent of water and arises from the dissolution of mineral 

sulphates in soil and rock, particularly calcium sulphate (gypsum) and other partially 

soluble sulphate materials. Sulphates tend to accumulate to progressively increasing 

concentrations when added to water. Examples of sulphates that can be discharged 

to the receiving water environment include acid mine drainage and other industrial 

processes using sulphuric acid. Sulphates can be removed or added to water by ion 

exchanges processes and microbial reduction. The microbial processes tend to be 

slow and require anaerobic conditions usually only found in sediments and soils. 

High concentrations of sulphate exert predominantly acute health effects (diarrhoea). 

These effects are temporary and reversible since sulphate is rapidly excreted in the 

urine. Individuals exposed to elevated concentrations in their drinking water for 

periods become used to the sulphate and adapt and will not experience these 

effects. However sulphate concentrations of more than 600 mg/ℓ will result in 

diarrhoea and adaptation will not occur (DWAF Domestic, 2006). 

Silica 

Silicon is the second most abundant element in the earth's crust after oxygen and 

makes up 27.7 % thereof. It occurs predominantly as silica or as various silicates. 

Silica is found in low concentrations in all natural waters given its universal 

occurrence. Silica is of relatively low solubility in water. The solubility of silicates in 

water depends on the nature of the metal cations present. Most metal silicates are 

insoluble in water, with the exception of the silicates of sodium and potassium, which 

are highly soluble in water. Under alkaline conditions, the solubility of silica is 

enhanced. The solubility of silica is also affected by particle size and temperature. 

The insolubility of transition metal silicates implies that silica will tend to be 

reprecipitated onto sediments. 

Depending on the concentrations of silica it may damage equipment and structures, 

interfere with industrial processes; impact on product quality and complicate 

July 2012 5-23



treatment and/or disposal of wastes generated as a result of the concentration of 

silica (DWAF, 2006 Industrial). 

Iron 

Iron is abundantly found in the earth’s crust. It is found in many minerals, the most 

common of which is haematite (Fe2O3) widely used as an iron ore for metallurgical 

purposes (DWAF: Industrial, 1996). Other important iron minerals are pyrite (FeS2). 

This is usually associated with coal formations and iron may also its elemental form, 

either as terrestrial iron or as meteoric iron. Iron is removed from water using 

oxidising process which converts the iron into an insoluble oxide removable by 

filtration. Elevated concentrations can result in damage to equipment and structures. 

Damage to equipment may occur in two ways. On precipitation in contributes to the 

sediment deposits which foul boilers, heat exchangers and pipelines. Localised hot 

spots occurring under such iron precipitates in boilers or heat exchangers may result 

in overheating and subsequent structural damage. The fouling on ion exchange 

resins can reduce their ion exchange efficiency. 

Manganese 

Manganese like iron is an abundant element of the earth’s crust. Manganese is an 

essential element for humans and animals but is neurotoxic in excessive amounts. 

At typical concentrations encountered in water manganese has aesthetic rather than 

toxic effects. Elevated concentrations of Mn can result in fouling and therefore the 

same effects as iron. Resin exchange capacity of ion exchange columns may be 

destroyed by the accumulation of manganese precipitates within the resin structure 

(DWAF: Industrial, 1996). 

The median, 75 th percentile and the 95 th percentile were determined for all the 

variables that were measured by the Lesotho Highlands monitoring programme. This 

provides an indication of the water quality in the Katse Dam at various points. 

However it must be noted that the sampling of the monitoring points were scaled 

down to at least four times a year from a monthly monitoring programme in the past 

therefore this may not necessarily present a realistic snap shot of the current water 

quality. 

The water quality data was compared to the South African Water Quality Guidelines 

for Domestic Use, Agricultural Use (Livestock watering and irrigation), Industrial use 

and then to the Aquatic environment for variables of concern. These variables were 

determined based on the potential impacts that the activity may have on the receiving 

environment. 

July 2012 5-24



5.3 FITNESS FOR USE 

Water quality does not suddenly change from “good” to “bad”. Instead there is a 

gradual change between categories and this is reflected by the fitness-for-use range 

which is graded to indicate the increasing risk of using the water. 

Water quality criteria are discrete values that describe a specific effect as a result of 

a particular set of conditions. These criteria are then used to develop guidelines, 

which describe the effect on a user who is exposed to an ever increasing 

concentration or changing value. 

Water quality criteria are used to describe the fitness-for-use. The fitness-for-use 

range can be divided into four sections which are classified as four categories, 

ranging from “ideal” to “unacceptable”. These categories are described as: 

Ideal : the user of the water is not affected in any way; 

Acceptable : slight to moderate problems are encountered; 

Tolerable : moderate to severe problems are encountered; and 

Unacceptable : the water cannot be used under normal circumstances. 

The fitness-for-use range is colour coded for ease of interpretation of information 

during the assessment of the water quality (Table 5-2). 

Table 5-2: Colour codes assigned to fitness for use ranges 

Fitness for use range Colour code 

Ideal Blue 

Acceptable Green 

Tolerable Yellow 

Unacceptable Red 

5.3.1 Identification of fitness-for- use 

In 2009 Orasecom undertook an assessment of the fitness for use and provided an 

assessment of the suitability of use for both ground and surface water in the Orange 

– Senqu basin based on key water quality parameters. During this assessment the 

South African Water Quality Guidelines and Standards were used as one of the 

standards available to assess the situation. Therefore, it was decided that these 

Water Quality Guidelines will once again be used to determine the fitness for use of 

the water quality in the Katse Dam and the potential impact on the water quality. 

The Water quality guidelines describe the fitness-for-use of the water. The biological, 

chemical or physical data is analysed and the results are compared against the 

guidelines to assess the water quality of a resource. 

July 2012 5-25



It is therefore necessary that water quality guidelines be identified for each water use 

and for each variable of concern. The basis of these guidelines can be found in the 

South African Water Quality Guidelines, Volumes 1 to 7 (DWAF: Domestic, 1996), 

(DWAF: Ecosystems, 1996), (DWAF: Irrigation, 1996), (DWAF: Industrial, 1996 

Category 1) and (DWAF: Livestock, 1996). Category 1 for Industrial use was 

considered as this requires the most stringent quality of water for industrial use. The 

water is used for cooling water, steam generation, process water and wash water. 

The DWA water quality guidelines make provision for five water use categories, 

namely domestic, recreation, industrial, agricultural (irrigation, livestock watering, and 

aquaculture) and the aquatic ecosystem. 

For the purposes of this study four of the five water use categories have been taken 

into account, namely domestic use, industrial, agricultural use (irrigation and livestock 

watering) and the aquatic ecology, as the other are not relevant to the catchment in 

the study area. 

The water quality guidelines identified for the abovementioned water uses for the 

variables of concern are summarised in Table 5-3 to Table 5-5. 

5.3.2 Combined Fitness-For-Use Classification 

The cut-off values for the fitness for use categories are per user and per variable and 

can be used to assess the fitness for use of the water in the Katse Dam for individual 

uses or user categories such as domestic, agriculture, industry, recreation and the 

aquatic ecosystem. 

In order to determine the fitness for use of the water resource in the Katse Dam as a 

whole, the different fitness for use categories for different users affected by the same 

variable were reconciled. 

This was done by selecting the most stringent value, in other words the value for the 

most sensitive use to water quality deterioration, for each cut-off value in order to 

arrive at the management levels or combined fitness-for-use. 

The summary of the combined fitness-for-use values are given in Table 5-6. The 

majority of variables were determined by the industrial use guidelines. 

July 2012 5-26



Table 5-3: User Specific Guidelines: Domestic (DWAF, 2006) 

Variable Units Ideal Acceptable Tolerable Unacceptable 

DOMESTIC (SA) 

Alkalinity mg CaCO3 

Chemical Oxygen 

Demand 

mg O2 

Electrical Cond. mS/m < 70.00 70.00 to 150.0 150.0 to 370.0 > 370.0 

pH (lower range) pH units > 5.00 5.00 to 4.50 4.50 to 4.00 < 4.00 

(upper range) < 9.50 9.50 to 10.00 10.00 to 10.50 > 10.50 

Iron mg/l Fe 0.10 0.10 0.30 0.30 1.00 1.00 

Manganese mg/l Mn 0.05 0.05 0.15 0.15 1.00 1.00 

Nitrate / Nitrite mg/l N < 6.00 6.00 to 10.00 10.00 to 20.00 > 20.00 

Ammonia mg/l < 1.00 1.00 to 2.00 2.00 to 10.00 > 10.00 

Chloride mg/l < 100.0 100.0 to 200.0 200.0 to 600.0 > 600.0 

Phosphate mg/l P 

Silica mg/l Si 

Sulphate mg/l < 200.0 200.0 to 400.0 400.0 to 600.0 > 600.0 

Suspended solids mg/l 

July 2012 5-27



Table 5-4: User Specific Guidelines: Industrial (DWAF, 2006) 


INDUSTRIAL (SA) 

Alkalinity mg CaCO3 < 50 50 to 120 120 to 300 > 300 


Demand 

mg O2 < 10 10 to 30 30 to 50 > 50 

Electrical Cond. mS/m < 15 15 to 30 30 to 70 to 70 

pH (lower range) pH units 7.00 6.00 to 7.00 < 6 

(upper range) 8.00 8.00 to 9.5 > 9.5 

Iron mg/l Fe < 0.1 0.1 to O.3 0.3 to 1.0 > 1.00 

Manganese mg/l Mn < 0.05 0.05 to 0.2 0.2 to 1.0 > 1.00 

Nitrate / Nitrite mg/l N 

Ammonia mg/l 

Chloride mg/l < 20 20 to 50 50 to 120 > 120 


Silica mg/l Si < 5 5 to 10 10 to 20 > 20 

Sulphate mg/l < 30 30 to 80 80 to 150 > 150 

Suspended Solids mg/l < 3 3 10 10 to 25 > 25 

July 2012 5-28



Table 5-5: User Specific Guidelines: Agriculture & Ecology (DWAF, 2006) 

Variable 

AGRICULTURE: 

Irrigation (SA) 

Units Ideal Acceptable Tolerable Unacceptable 



Demand 

mg O2 


pH (lower range) pH units > 6.50 < 6.50 

(upper range) < 8.40 > 8.40 

Iron mg/l Fe 0.2 0.2 0.75 0.75 1.5 1.5 




Chloride mg/l < 100.0 100.0 to 175.0 175.0 to 700.0 > 700.0 



Sulphate mg/l 

Suspended Solids 

AGRICULTURE: 

Livestock Watering 

(SA) 

mg/l 50 50 75 75 100 100 



Demand 

mg O2 


pH pH units 

Iron mg/l Fe 10 10 20 20 50 50 

Manganese mg/l Mn 10 10 20 20 50 50 


July 2012 5-29





Chloride mg/l < 1<strong>000</strong>. 1<strong>000</strong>. to 1750. 1750. to 2<strong>000</strong>. > 2<strong>000</strong>. 



Sulphate mg/l < 1<strong>000</strong>. 1<strong>000</strong>. to 1250. 1250. to 1500. > 1500. 

Suspended Solids 

ECOLOGICAL (SA) 

mg/l 



Demand 

mg O2 

Electrical Cond. mS/m 

pH pH units 

Iron mg/l Fe 

Manganese mg/l Mn 



Chloride mg/l 

Phosphate mg/l P < 0.01 0.01 to 0.03 0.03 to 0.25 > 0.25 


Sulphate mg/l < 1<strong>000</strong>. 1<strong>000</strong>. to 1250. 1250. to 1500. > 1500. 

Suspended Solids mg/l 

July 2012 5-30



Table 5-6: Combined Fitness-for-Use Categories 


Alkalinity mg CaCO3 50.00 50 120 120 300 300 


Demand 

mg O2 10.00 10 30 30 50 50 

Electrical Cond. mS/m < 15.00 15 to 30 30 to 70 > 70 

pH (lower range) pH units > 7.00 6.00 to 7.00 < 6 

(upper range) < 8.00 8.00 to 9.50 > 9.5 

Iron mg/l Fe < 0.1 0.1 to O.3 0.3 to 1.0 > 1.00 




Chloride mg/l < 20 20 to 50 50 to 120 > 120 

Phosphate mg/l P < 0.01 0.01 to 0.03 0.03 to 0.25 > 0.25 

Silica mg/l Si < 5 5 to 10 10 to 20 > 20 

Sulphate mg/l < 30 30 to 80 80 to 150 > 150 

Suspended Solids mg/l < 3 3 10 10 to 25 > 25 

July 2012 5-31



The explanation of how the cut-off values for each of the water quality variables were 

decided on, are described below: 

Alkalinity: 

The industrial guideline was the only guideline for alkalinity. The ideal range falls 

below 50 mg/l. 

Chemical Oxygen Demand (COD) 

Chemical oxygen demand is determined by the industrial guidelines and requires an 

ideal category of less than 10 mg/l. 

Electrical Conductivity (EC): 

The industrial guideline is the most stringent. The ideal range in this guideline falls 

between 0 and 15 mS/m. 

pH: 

The fitness for use for the pH category simply represents a combination of all the 

user-specific guidelines to form the most stringent. 

Iron (Fe) 

The industrial and domestic guidelines have the most stringent requirements 

regarding iron concentrations in the water. 

Manganese (Mn) 

The irrigation guidelines determined the ideal and acceptable range while the 

industrial guideline requires a lower range for tolerable and unacceptable ranges. 

Nitrate and Nitrite (NO2/NO3): 

Nitrate/Nitrite concentrations are important in domestic and for irrigation use. 

However, it is more stringent for domestic use. 

Ammonia (NH4): 

There are guidelines for ammonia in the domestic and ecological user groups. It is, 

however, more stringent in ecological use. It is also an existing variable within the 

existing data and gives a good indication of water quality for domestic use. 

Chloride 

The chloride concentrations are important in industrial uses and require lower 

concentrations as that of domestic use. 

Phosphorous (PO4): 

The only guideline for phosphorous is in the ecological user group. 

July 2012 5-32



Suspended solids (SS) 

Industrial use determined the guidelines and is more stringent than the guidelines for 

irrigation use. 

Silica (Si) 

The industrial guideline has the only requirement for Silica. 

Sulphate 

Industrial use has strict requirements for sulphate concentrations and determined the 

combined fitness for use guidelines. 

Table 5-7: Water quality assessment category 

Fitness for use range in which the variable falls 

Median 75 th percentile 95 th percentile 

Water quality 

assessment 

category 

Colour code 

Ideal Ideal Ideal Ideal Blue 

Ideal Ideal Acceptable 

Ideal Acceptable Acceptable 

Acceptable Acceptable Acceptable 

Ideal Ideal Tolerable 

Ideal Acceptable Tolerable 

Acceptable Acceptable Tolerable 

Acceptable Tolerable Tolerable 

Tolerable Tolerable Tolerable 

Acceptable Green 

Tolerable Yellow 

Any other combination Unacceptable Red 

For instance, if the median is in the ideal range, the 75 th percentile is in the 

acceptable range and the 95th percentile is in the tolerable range, then the water 

quality assessment category is “tolerable” as set out in the Table 5-7. 

This methodology thus tests a set of data in a consistent and unbiased manner, 

taking into consideration the water quality, of each of the variables of concern, for the 

full range of fitness-for-use (median, the 75 th and the 95 th percentiles) of the water for 

a specific resource. In this methodology the full time span of the water quality of the 

resource is checked in an acceptable scientific manner in the same way one sample 

would be checked for fitness-for-use. 

July 2012 5-33



5.4 DATA ANALYSIS 

The median, 75 th percentile and 95 th percentile for each variable were determined as 

indicated in Table 5-8. From the data it can be determined that the water has a low 

alkalinity and a median pH between 8 and 9. The median temperature of the various 

monitoring points varies between 14°C and 17°C. The Electrical conductivity at all 

the stations is less than 10 mg/ℓ with the sulphate concentrations below 10 mg/ℓ, 

sodium below 5 mg/ℓ and magnesium below 5 mg/ℓ. It appears that all the metals are 

generally below the detection limit of the laboratory used to analyse the samples. 

The only variable that seems to be an issue is suspended solids. The 95 th percentile 

for suspended solids was reported to be 34 mg/ℓ at Bokong (compared to a median 

of 5 mg/ℓ) and 29.7 mg/ℓ at Kdamusurf. 

Dissolved nitrogen and phosphate levels also appears to be very low, ammonia is 

below 0.33 mg/ℓ, nitrates are below 0.5 mg/ℓ and phosphates are below 0.23 mg/ℓ. 

From previous experience in the catchment there is reason to believe that there are 

some anomalies regarding the data: 

The pH is very high given the nature of the catchment, 

Manganese seems to be high, 

PO4 is very high and could not be attributed to the geology or anthropogenic 

activities around the dam 

The occasional high suspended solids may be due to sampling errors or due 

to stor<strong>mw</strong>ater runoff and may not be representative of the dam as a whole. 

5.5 WATER QUALITY ASSESSMENT DISCUSSION 

The current water quality in the vicinity of the project area is presented in Table 5-8. 

The combined fitness for use is applied to the water quality assessment indicated in 

the Table 5-9. The ideal water quality is presented in blue, acceptable in green, 

tolerable in yellow and unacceptable in red. 

The water quality for the dam indicates that electrical conductivity, chlorides, 

alkalinity and sulphates falls within an ideal category. Chemical oxygen demand, 

iron, pH and ammonia fall in the acceptable category, while phosphates fall within a 

tolerable level. The only variable that fell in an unacceptable category at various 

monitoring points was suspended solids for the 95 th percentile and some of the 

median for these monitoring points also fell in the unacceptable category. The 

reason for these high suspended solids may be depended on the locality of the 

monitoring point and external factors such as strong wind that results in wave action 

and this cause the sediment to come into suspension, or due to the rainstorm events 

which result in high loads of sediment transported to the receiving catchment. 

July 2012 5-34



The water quality recorded for the Bokong River and that of the Katsee Dam is 

homogeneous. Therefore it can be accepted that the water quality for the Kobong 

River will be the same as that of the Bokong River and Katse dam. 

July 2012 5-35



Table 5-8: Variables that are analysed as part of the water quality monitoring programme in the Katse Dam 

July 2012 5-36



Table 5-9: Fitness for use of the water quality in the Katse Dam 

Bokong 

DOf 

mg/l 

Temp 

o 

C 

Ec 

mS/m 

pH 

Cl 

mg/l 

COD 

mg/l 

Fe 

mg/l 

F 

mg/l 

Hard 

Mg/l 

K 

mg/l 

M Alk 

mg/l 

Mg 

mg/l 

Mn 

mg/l 

Na 

mg/l 

NH4 

mg/l 

NO2 

mg/l 

NO3 

mg/l 

P 

mg/l 

P 

ALK 

PO4 

mg/l 

S 

mg/l 

Si 

mg/l 

SO4 

mg/l 

SS 

mg/l 

TDS 

mg/l 

95 Percentile 11.00 22.76 8.58 9.02 10.00 20.55 0.13 0.15 43.00 0.70 40.00 3.75 0.15 4.78 0.14 0.10 0.40 0.50 2.50 0.17 1.89 12.75 6.29 34.10 96.15 

75th Percentile 9.34 18.90 7.40 8.50 5.00 7.50 0.05 0.08 34.00 0.69 35.00 2.90 0.05 2.20 0.07 0.03 0.15 0.14 2.50 0.04 1.30 6.50 2.50 8.00 63.00 

Median 8.47 14.70 5.80 8.10 2.50 5.00 0.03 0.06 27.00 0.25 27.00 2.20 0.03 1.50 0.03 0.03 0.05 0.10 2.50 0.03 1.00 5.80 2.50 5.00 54.00 

Water quality 

Category 

Kda<strong>mw</strong>surf 

95 Percentile 10.84 22.70 10.00 9.51 2.50 19.70 0.06 0.14 45.99 0.79 41.00 4.20 0.15 4.40 0.14 0.10 0.48 0.50 2.50 0.13 1.80 7.26 6.57 15.20 100.00 

75th Percentile 8.50 20.50 8.52 8.91 2.50 11.50 0.03 0.09 38.00 0.70 39.00 3.50 0.05 2.40 0.06 0.04 0.20 0.15 2.50 0.05 1.50 6.90 5.00 5.00 71.00 

Median 7.60 16.78 7.80 8.30 2.50 5.00 0.03 0.07 35.50 0.34 37.00 3.20 0.03 1.80 0.03 0.03 0.11 0.12 2.50 0.03 1.30 6.60 2.50 5.00 62.00 

Water quality 

Category 

Kdamisurf 

95 Percentile 11.52 22.60 9.16 9.37 2.50 20.00 0.09 0.40 43.75 0.70 42.95 4.07 0.15 3.56 0.16 0.09 0.33 0.50 2.50 0.15 1.80 7.57 7.25 14.00 93.30 

75th Percentile 8.65 20.555 8.50 8.68 2.50 7.50 0.04 0.082 38 0.65 39.00 3.5 0.05 2.3 0.08 0.05 0.17 0.163 2.5 0.03 1.5 7.10 5.00 5.00 70 

Median 7.7 16.9 7.80 8.19 2.50 5.00 0.03 0.1 35.5 0.3 37.00 3.2 0.03 1.8 0.03 0.0 0.1 0.1 2.5 0.03 1.3 6.75 2.50 5.00 64.0 

Water quality 

Category 

Kdamusurf 

95 Percentile 10.58 22.25 9.19 9.36 3.48 22.10 0.13 0.14 44.00 0.70 40.00 3.97 0.15 4.71 0.16 0.08 0.40 0.50 2.50 0.19 1.85 8.00 8.45 29.70 101.80 

75th Percentile 8.95 20.07 8.00 8.55 2.50 11.00 0.05 0.08 37.00 0.62 38.00 3.40 0.05 2.40 0.08 0.05 0.22 0.20 2.50 0.05 1.50 7.05 5.00 5.00 67.75 

Median 7.91 16.26 7.40 8.03 2.50 5.00 0.03 0.06 34.00 0.26 36.00 3.10 0.03 1.70 0.03 0.03 0.14 0.12 2.50 0.03 1.30 6.50 2.50 5.00 60.00 

Water quality 

Category 

Kdamtsurf 

95 Percentile 11.05 22.50 9.64 9.40 2.50 17.90 0.18 0.20 43.25 0.74 42.00 4.00 0.15 4.93 0.21 0.07 0.38 0.50 2.50 0.12 1.80 16.00 6.88 13.00 98.55 

75th Percentile 8.99 19.87 8.33 8.83 2.50 9.00 0.04 0.08 38.00 0.61 39.00 3.40 0.05 2.40 0.08 0.04 0.20 0.15 2.50 0.03 1.60 7.03 5.00 5.00 70.75 

Median 7.83 16.34 7.60 8.20 2.50 5.00 0.03 0.06 35.00 0.30 36.00 3.20 0.03 1.70 0.03 0.02 0.13 0.11 2.50 0.03 1.30 6.65 2.50 5.00 63.00 

Water quality 

Category 

July 2012 5-37



6. IMPACT ASSESSMENT 

The impact assessment considered the assessment of the potential surface water 

impacts associated with the construction, operational and closure and 

decommissioning phase of the construction of the dam and the powerline. Impacts 

were assessed taking into consideration the construction method and it was 

assumed that best practices will be implemented throughout the project. 

6.1 PRE-CONSTRUCTION PHASE: 

The main activities during the pre-construction phase were set out in the previous 

chapter but will be repeated for easy reference. 

Materials investigation, 

Geological drilling, 

Site surveying, 

Mitigation of impacts on identified heritage resources, and 

Plant rescue 

6.1.1 Surface water quality 

Surface water quality may be impacted upon during the pre-construction phase due 

to the following: 

Hydrocarbon spillages from the drills and survey equipment, 

Sludge generated during the drilling not disposed of correctly may result in 

contamination due to high suspended solids, and 

Clearing of vegetation to construct access roads for drilling and survey 

equipment may generate an increase in suspended solids during rainfall events. 

Soil compaction due to the equipment that is used during the survey resulting in 

an increase in runoff during rainstorm events. 

At the time of writing this report it was not clear how many holes will be drilled and 

where. It was also not clear how access to the various sites will be obtained; 

therefore a conservative approach was adopted to assess potential impacts on the 

surface water quality. The relief differs from high to extremely high with various 

smaller streams and drainage lines draining the area. The water will therefore tend 

to flow away. Should a hydrocarbon spillage therefore occur the probability exist that 

the hydrocarbons or contaminated runoff will enter a drainage line and move off site 

July 2012 6-1



and therefore have a regional impact. Although the impact will be of short duration 

during a storm event and a few hours thereafter it will occur throughout the preconstruction 

phase. Should the impact materialise it may reduce the functionality of 

the surface water and may result in a negative impact. 

The potential significance of impacts is set out in the table below. 

July 2012 6-2



Table 6-1: Significance table of impacts on water quality during the pre-construction phase 

Water quality Pre-mitigation Post-mitigation 

Potential impact Extent Duration Intensity Probability Confidence Significance Extent Duration Intensity Probability Confidence Significance 

Contamination of the receiving water 

due to hydrocarbon spillages 

Contamination of surface water due to 

irresponsible disposal of sludge during 

the drilling 

Increase in turbidity resulting in 

sedimentation due to runoff from areas 

that are cleared 

Regional 


Short 

term 

Short 

term 

Regional Short 

term 

Low Medium High LOW Local 

Medium Medium Medium MEDIUM Local 

Medium Medium High MEDIUM Local 

July 2012 6-3 

Short 

term 

Short 

term 

Short 

term 

Low Medium HIGH LOW 

Low Medium Medium MEDIUM 

Low Medium High MEDIUM 

Although mitigation measures will be implemented as discussed in the next chapter and the impact will be localised the impact is likely 

to occur should the measures not be implemented. 

Mitigation measures may include but will not be limited to: 

Hydro carbon spillages shall be contained to the smallest footprint, cleaned and rehabilitated immediately, 

Sludge generated during the drilling phase shall be disposed of in a manner that it will not impact on any receiving surface water 

e.g. disposal of the sludge to a sedimentation pond, 

Clearing of areas shall be kept as small as possible.



6.2 CONSTRUCTION PHASE 

The main construction activities will include the following the construction of: 

the upper reservoir, 

access roads including a main access road to the construction site and 

temporary haul roads, 

Electrical infrastructure, 

Associate infrastructure on or near the site including a temporary 

 

accommodation construction camp near Kobong Village, 

Borrow pit will be located within the dam basin, 

Permanent camp 

Temporary construction camp which include: 

o Concrete batching plants, 

o Site offices and parking, 

o Workshops and stores, 

o Helipad, 

o Weather Station, 

o Sand and crushed stone stockpiles, 

o Hazardous substance areas, 

o Explosive <strong>storage</strong> magazines, 

o Wash bays or the construction plant, 

o Facilities for bulk <strong>storage</strong> and dispensing for construction vehicles 

o Power lines, 

o Small scale sewage treatment plant, and 

o A temporary solid waste disposal facility. 

The surface water quality may be impacted upon during the construction phase due 


Clearing of vegetation, 

Contamination of stor<strong>mw</strong>ater, 

Spillages of hydrocarbons/dangerous goods, 

Discharging water found in the borrow pit and tunnel with high suspended solids, 

Disposal of general waste, 

Provision of insufficient sanitation, 

July 2012 6-4



6.2.1 Impacts of the upper reservoir on the upper tributaries of the Kobong River 

During the construction of the upper reservoir, the upper catchment of the Kobong 

River will be highly modified and the receiving environment changed in such a way 

that it will not function as it did previously. The catchment of the Upper Reservoir is 

small compared to the catchment of the Katse Dam. The upper reaches of the 

reservoir is dependent on direct rainfall and snow melting during the winter periods. 

The impact will continue from the construction phase through to the operational 

phase and is considered to be permanent. 

6.2.2 Surface water quality 

Site clearing 

Surface water quality may be impacted upon during site clearing and construction of 

various infrastructure: 

Sedimentation may cause an increase in runoff from cleared areas or from 

stockpiled areas which will result in an increase in suspended solids, 

Change in drainage of areas, and 

Soil compaction causing an increase in runoff during rainstorm events from 

cleared areas. 


Clearing of areas for the construction shall be kept to the smallest possible 

footprint 

Separation of clean and dirty water shall be implemented 

Sensitive areas shall be demarcated to prevent unauthorised travelling in 

sensitive areas in order to prevent soil compaction 

Access routes shall be determined and kept to the minimum in order to prevent 

the whole area being used by construction equipment 

July 2012 6-5



Spillages of hydrocarbons 

The construction site will be established within the upper reaches of the tributary of the Kobong River. The catchment is relatively small 

and therefore impacts associated with spillages within the dam area will be localised and will only occur for the duration of construction. 

Due to the nature of construction the probability of a spillage occurring remains likely. However, this impact will remain within the dam 

basin and will not be transferred downstream. The project may change the surface water quality but the ecosystems will still function in 

the modified way. Therefore the impact on the surface water quality environment will be of a MEDIUM significance as indicated in the 

table below. 

Table 6-2: Significance table associated with spillages of hydrocarbons during the construction phase 



Contamination of water due to 

hydrocarbons 

l 

o Local 

c 

Short 

term 


July 2012 6-6 

Short 

Term 

Low Medium HIGH LOW 

Although the impact will remain localised it is still important to implement procedures to prevent, reduce and mitigate spillages within the 

dam basin. 


Clean and dirty water shall be separated on the construction site, 

Contaminated runoff shall be contained, 

Oil traps shall be installed in all working areas,



Construction vehicles shall be serviced in a demarcated area and not in the field, and 

Once construction machinery is parked in an area, they shall have drip trays to contain any spillages from the equipment. 

Contaminated stor<strong>mw</strong>ater runoff 

The construction yard, crushing plants and the batch plant will be constructed downstream of the new dam wall. Contaminated runoff 

from the batch plant providing concrete for the construction and from the crushing plants providing aggregate for the infrastructure might 

enter the Kobong River and result in the sedimentation of the river downstream and increase in turbidity. The impact will occur 

throughout the construction phase and is likely to occur if there are no stor<strong>mw</strong>ater control measures in place. 

Table 6-3: Significance table for contaminated runoff from the construction yard, crushing and batch plants 



Contaminated runoff leaving the batch 

plant and the stockpiles will increase in 

turbidity resulting in sedimentation of the 

Kobong River downstream from the dam 

wall 


Short 

term 


July 2012 6-7 

Short 

term 

Low Medium High LOW 

Depending on the volume of the spillages the impact may leave the site and extend downstream of the Kobong River which will have a 

regional impact. However the Kobong River discharges directly into the Katse Dam. Any sediment will settle out in the immediate 

vicinity of the discharge point therefore the extent will remain localised. It is assumed that best practices will be implemented on site 

and spillages will be addressed immediately and therefore the impact will be of short duration and only applicable to the construction



phase. As mitigation measure procedures and stor<strong>mw</strong>ater control will be implemented to ensure that no contaminated runoff will enter 

the Kobong River and therefore reduce the impact to a LOW significance. 


All clean and dirty water shall be separated where possible. Clean water shall be diverted away from the site and contaminated 

water shall be contained, settled out and only then discharged. 

Spillages of dangerous goods 

Spillages of dangerous goods at the point of <strong>storage</strong> will be localised and have a medium intensity. Should it reach the Kobong River 

and result in the contamination of the surface water, the ecosystems may be altered and even cease to exist. The probability of this 

happening is likely if control measures are not implemented. 

Table 6-4: Significance table for the spillages of dangerous goods 



Spillages of dangerous goods at the 

point of <strong>storage</strong> 


Short 

term 

High Medium High HIGH Local 

July 2012 6-8 

Short 

term 

Low LOW High LOW 

The impact will be mitigated from a HIGH significance with the implementation of mitigation measures to an impact with a LOW 

significance.




A spillage shall be contained to the smallest possible area, 

Spillages shall be cleaned and rehabilitated as soon as possible 

Discharging water containing high concentrations of suspended solids 

Discharging water accumulating in the borrow areas, excavations and even the tunnel in order to continue with construction activities 

may result in the increase in turbidity and result in sedimentation. The probability that the water can enter the Kobong River is likely due 

to the short distance to the river. The impact will therefore extend to a regional context, the probability that runoff will impact the water 

quality in the Kobong River is likely and this will result in the change of the water quality but will probably still function in a modified way. 

The baseline data indicated that the suspended solids are the only variable for which the 95 th percentile falls within the unacceptable 

category and therefore the probability of increase in turbidity and sedimentation is most likely and therefore the impact is of a MEDIUM 

significance. 

Table 6-5: Significance table for water discharged with a high concentration of suspended solids 



Increase in turbidity and sedimentation 

in the Kobong River due to the 

discharge of water found in tunnel, 

borrow pit and excavations 


Short 

term 

Medium Medium High MEDIUM Regional 

July 2012 6-9 

Short 

term 

Low Low High LOW



With the implementation of mitigation measures the impact can be reduced from medium to low by reducing the probability of the impact 

occurring. 


Clean stor<strong>mw</strong>ater shall be diverted away from any excavations 

No silt laden water shall be discharged directly to the environment 

Silt laden water shall be diverted through a sedimentation pond before release or reuse of water 

Where necessary apparatus shall be installed to recover any hydrocarbons form the surface of the water. 

Recovered hydrocarbons must be stored in a bunded covered area to prevent any further water being contaminated 

Recovered oils will be removed by an approved service provider 

The necessary safe disposal certificates and waste manifests will be made available on disposal 

Waste management 

The disposal of general waste, cement bags and hazardous waste during the construction period can potentially contaminate runoff if 

not managed properly. The receiving environment can be significantly altered if this is not disposed to a proper designed landfill site. 

The impacts will be localised if it does not leave the property but if the contaminated runoff reaches the river it will impact on the region. 

The impact will occur throughout the construction period. The impact due to irresponsible waste disposal is likely to occur if the 

necessary measures are not implemented to ensure that this does not happen. 

July 2012 6-10



Table 6-6: Significance table for waste management 



Surface water contamination due to 

irresponsible disposal of general and 

hazardous waste 


Short 

term 

Medium Medium High MEDIUM Regional 

July 2012 6-11 

Short 

term 

Low Low High LOW 

The necessary measures must be implemented to ensure that waste is disposed of to an approved site to prevent any contamination of 

soils and surface water runoff. 

Provision of Sanitation 

The provision of sanitation in the form of chemical toilets and the disposal of the contents from the chemical toilets to a waste water 

treatment works (WWTW) will potentially have an impact on the quality of the effluent from the receiving waste water treatment works. 

The intensity of the impact will depend on the volume of sewage that is received at the WWTW. The intensity is considered to be 

medium as the impact can change the environment significantly and will remain for the duration of the construction phase. WWTW will 

be constructed at various points where a concentration of people occur such as the construction yard, crushing and batching plants and 

the labour camps B and C. It would most probably be package plants bought off the shelf for a specific purpose. These package plants 

function well provided that they are not hydraulically overloaded. Due to the movement of people and contractors on a project such as 

this, it is likely that the sewage plant can be overloaded when high numbers of labourers are required and this results in an effluent that 

does not comply with the necessary discharge standards. The impact will be of a regional importance, and might be of short duration 

once the impact is identified and mitigated. The probability of this happening is likely as the residents in the labour camps change 

depending on the construction needs throughout the project life cycle.



Table 6-7: Significance of the provision of sanitation 



Surface water contamination due final 

treated effluent not complying to final 

effluent standards 


Provision shall be made for sanitation, 

Regional Medium Medium Medium High MEDIUM Regional Medium Low Low High LOW 

Effluent discharged shall comply with the relevant regulations, and 

Use of chemical toilets shall be limited as far as possible 

Construction of access roads and pylons across rivers 

New access roads constructed to the site and pylons will cross various rivers. The construction of river crossings may result in the 

increase in turbidity and result in sedimentation downstream of the river crossings. The duration of the impact will be of short duration, 

the intensity will be medium as the environment will be significantly changed but it is foreseen that the environment will still function in its 

modified way. 

July 2012 6-12



Table 6-8: Impacts associated with the construction of river crossings 



Increase in turbidity and sedimentation 

due to construction of river crossings 

Regional Medium Medium Medium High HIGH Regional Medium Low Medium High LOW 

The HIGH significant impact will be mitigated to an impact with a LOW significance. 


No pylons shall be constructed within a river or within the 1: 100 year flood line, 

Construction of the river crossings shall be limited to the smallest potential foot print, and 

Erosion control measures shall be implemented to prevent water containing high concentrations of suspended solids entering the 

river downstream of the workings. 

6.2.3 Stor<strong>mw</strong>ater 

Stor<strong>mw</strong>ater management during the construction of the dam, the construction yards, waste management facilities, labour camps and at 

the batch plants will have an impact on the surface water. Clearing of the vegetation and stockpiling topsoil for the construction of 

infrastructure will increase the runoff from the areas in more contaminated water to be handled and managed. The probability that the 

water will reach the Kobong River or the Katse dam is likely. The impact will occur throughout the construction phase. 

July 2012 6-13



Table 6-9: Impact associated with stor<strong>mw</strong>ater management 



Contaminated stor<strong>mw</strong>ater impacting on 

the downstream water quality 

Regional Medium Medium Medium High MEDIUM Regional Medium Low Low High LOW 

If mitigation measures are applied, the significance of impacts associated with stor<strong>mw</strong>ater management will be reduced from a MEDIUM 

to a LOW significance. 

6.2.4 The operational phase 

During the operational phase water will be <strong>pumped</strong> from the Katse Dam to the Kobong Dam during periods when there is a low 

electricity demand. During periods of high electricity demand the water will be released from the upper reservoir to the lower Katse 

Dam to generate electricity. In general the dam will fill completely over weekends and then be empty towards the end of the week, 

residence time is therefore very short, and there will not be a significant change in the water quality. The water quality from the Katse 

Dam is expected to be the same as that of the Kobong River prior to construction and therefore it is not foreseen that the water released 

for the users downstream of the Kobong Dam will have an impact on the receiving environment or users. 

Impacts associated with the operational phase will be limited to: 

Potential increase in salinity due to the evaporation of water in the upper reservoir which may impact on the Katse Dam. The 

impacts associated with this are foreseen to be limited when the volume of water released from the Upper dam is compared with 

July 2012 6-14



the volume of the water in the Katse Dam. The period of one week presents a limited time frame wherein the water quality of the 

dam will change. Therefore it is expected that the operational phase will have a LOW significant impact on the water quality in the 

Katse Dam. 

It is expected from previous experience in the catchment that the water quality in Katse dam has a low buffering capacity and is 

considered to be aggressive which may impact on equipment and concrete. The pH of the water may also decrease with the 

increase of depth and therefore it will be important to ensure that the water abstracted from the Katse Dam to be <strong>pumped</strong> to the 

Kobong upper reservoir is withdrawn from various levels. 

The probability is low that the water can be contaminated with oils and grease due to the water coming into contact with oils and 

grease due to maintenance. The impact may be localised within the immediate area of the outlet and due to the volumes of water 

that will be released compared with the volume of water available in the Katse Dam the impact will be of a short duration and the 

intensity will be slight and may not even be noticeable. 

The treated effluent generated from the sewage works will remain throughout the operational phase. The impact will be of a 

regional nature should the effluent be released which does not comply with the standards. Untreated or partially treated effluent 

may result in increase of nutrients. However the probability that this will happen is not likely due the volume of effluent treated 

compared to the volume of water in the Katse Dam. The impact may be localised in the area where the water is released into the 

dam at the permanent labour camp. 

Table 6-10: Impact associated with the operational phase of the project 



Increase in salinity Local Low Medium Low High LOW Regional Medium Low Low High LOW 

July 2012 6-15





Damage to structures and equipment 

Contamination of water released from 

the tunnels with oils 

Increase in nutrients due to discharging 

water from the WWTW with a quality not 

complying with the standards 

L 

O Regional 

Local 

Local 

Long 

term 


term 


term 

Medium Medium High MEDIUM Regional Medium Low Low High LOW 

Low Medium High LOW Local Long term Low Low High LOW 

Low Medium High LOW Local Long term Low Low High LOW 

Although the impact is considered to have a LOW significance it will be important to implement the following mitigation measures: 

Include the monitoring of oils and greases in the water quality programme, 

Ensure that the WWTW is operated at the optimum level to ensure that all treated effluent complies with the discharge standards, 

Ensure that waste generated at the WWTW is disposed of responsibly so that it does not cause secondary pollution, 

July 2012 6-16



7. MITIGATION MEASURES 

The purpose of this chapter is to provide mitigation measures for the potential impacts that were identified in Chapter 5. 

Table 7-1: Environmental Management Programme for the Construction phase 

Aspect Impact Objective Performance 

indicator 

Run off from 

cleared areas 

Spillages of 

hydrocarbon 

materials from 

earthmoving 

equipment 

Increase in turbidity 

resulting in water 

contamination 

Increase in 

contaminated water 

that needs to be 

managed 

Potential soil erosion 

Contamination of 

soil resulting in 

contamination of 

water 

To prevent the 

erosion and increase 

in turbidity and 

increase in 


To prevent and 

minimise any 

hydrocarbons from 

entering any surface 

water streams 

No evidence of 

erosion 

No signs of silt laden 

runoff discharged 

over land 



discharged to the 

environment 

Management and mitigation measures 

Access roads shall be kept to the minimum and these will 

be clearly demarcated 

Construction of infrastructure shall not be delayed once 

vegetation is cleared 

Land clearing shall be kept to smallest possible footprint 

Silt laden runoff from cleared areas shall not be 

discharged directly overland and shall be contained and 

managed before reuse 

Overland discharges shall not result in erosion 

Where necessary water shall be diverted through a 

sedimentation pond to promote the settling of suspended 

solids 

Soil erosion protection measures will be employed where 

necessary e.g. protection berms 

Where cleared areas are not being used it must be 

rehabilitated 

All earth moving vehicles shall be put on a preventative 

maintenance schedule to ensure that equipment is in a 

good working order to prevent the leakages of oil and 

diesel 

An inspection programme shall be implemented to ensure 

that all mechanical equipment is inspected on a daily basis 

to ensure optimally functioning of equipment 

Vehicle maintenance areas shall be isolated from any 

clean stor<strong>mw</strong>ater systems. Drainage from these areas will 

July 2012 7-1




indicator 

Runoff from 

topsoil 

Increase in turbidity 

and erosion 

To prevent erosion 

and increase in 


erosion 


pass through an oil separator 

Oil removed from the oil separators shall be stored in 

suitable containers for recycling. An approved service 

provider which is a member of the Rose Foundation shall 

be used to remove the oil from site 

Refuelling of equipment shall occur in designated areas by 

trained people 

Bunding areas shall be provided for bulk <strong>storage</strong> of diesel, 

fuel, and oils which shall contain 110% of the volumes 

stored 

Spill kits shall be readily available to clean up spillages 

Drivers and operators shall be trained to use spill kits and 

contain spillages to the smallest possible areas 

Contaminated soil shall be removed to a demarcated area 

e.g. soil hospital for rehabilitation and replaced where 

necessary once rehabilitated 

Field maintenance shall be done in such a way as to 

prevent any spillages 

Drip trays shall be used when dispensing fuel or oils from 

the earthmoving equipment outside any demarcated areas 

for maintenance 

Drip trays shall be emptied into a dedicated container that 

will be used while vehicles are serviced in the field 

Dedicated drums must be emptied into containers for 

removal by an approved contractor to be recycled 

Waste manifests and safe disposal certificates must be 

filed as proof of safe disposal 

Topsoil stockpiles will be rehabilitated as soon as possible 

to prevent the increase in turbidity 

Stockpiles shall be shaped in such away that it will not be 

July 2012 7-2




indicator 

stockpiles turbidity in surface 

water 

Spillages of 

hazardous 

substances/ 

reagents e.g. 

ammonium 

nitrates during 

blasting 

Accumulation 

of runoff water 

in excavations 

or other areas 

(e.g. borrow 

Water contamination To prevent 

hazardous 

substances to enter 

the water 

environment and 

leaching later from 

stockpiles 

Water contamination 

– high in suspended 

solids 


increase in turbidity 

No evidence of silt 

laden runoff 




contamination or 

spills of hazardous 

substances 

No silt laden water 

shall be discharged 

directly to the 



higher than 3 m with side slopes of 45 degrees, be free 

draining and do not impound water 

Erosion control measures shall be implemented 

Runoff from the topsoil stockpiles shall be detained in 

order to support growth of vegetation 

Vegetation should be used to promote infiltration of water 

into the stockpile instead of increasing runoff 

A monitoring programme will be implemented whereby the 

vegetation of the stockpiles in terms of their basal cover 

and species diversity is monitored 

If it is noticed that the vegetation on the stockpiles is not 

sustainable, necessary actions will be taken to rectify the 

situation 

 

To use the correct amount of materials needed for 

optimum blasting 

Contain spillage to the smallest possible area 

Store the ammonium nitrates in a demarcated area with 

the necessary pollution control measures in place 

Spillages of material during the on and offloading of 

materials shall be contained to the smallest possible area 

within a bunded area 

Spillages must be contained and cleaned after delivering 

Clean stor<strong>mw</strong>ater shall be diverted away from any 

excavations 

No silt laden water shall be discharged directly to the 


Silt laden water shall be diverted through a sedimentation 

pond before release or reuse of water 

July 2012 7-3




indicator 


pits) Where necessary apparatus shall be installed to recover 

any hydrocarbons form the surface of the water. 

Recovered hydrocarbons must be stored in a bunded 

covered area to prevent any further water being 

contaminated 

Recovered oils will be removed by an approved service 

provider 

The necessary safe disposal certificates and waste 

manifests will be made available on disposal 

Removal of 

runoff water 

and ground 

from the tunnel 

Using 


runoff water for 

dust 

suppression 

on access and 

haul roads 

Construction 

activities 

including 

excavation, 

Contamination of 

surface water 



surface water 

To optimise the 

reuse of water from 

the tunnel 

Water contamination To contain all 


on site 

Water contamination To prevent 


surface runoff 

Water removed from 

the tunnel shall not 

be discharged to the 


Reuse all water from 

the open pit 

Prevent secondary 

pollution from dust 

suppression 

Project development 

must be within the 

identified footprint 

No silt laden water shall be discharged directly to the 


Silt laden water shall be diverted through a sedimentation 

pond before release or reuse of water 

Where necessary apparatus shall be installed to recover 

any hydrocarbons form the surface of the water. 

Haul roads within the dam basin shall be designed in such 

a way to divert runoff water to a dirty water system for 

reuse 

Water will be applied in such a way as to impede runoff or 

ponding on site and thus causing secondary contamination 

Clean stor<strong>mw</strong>ater will be diverted away 

All construction shall take place within the identified 

footprint 

No temporary structures shall be established outside the 

footprint area e.g. guard huts 

The disturbed area shall be kept to the smallest possible 

July 2012 7-4



Aspect 

and building of 

infrastructure 

Impact Objective Performance 

indicator 

Contamination 

from batch 

plants 

Water contamination To contain all 

contaminated runoff 

to the batch plant 

Crusher plant Contaminated runoff 

from the crusher 

plant 

Waste 

management 

disposal of 

hazardous 

substances (oil 


oily rags, 

To contain all 

contaminated runoff 

from the crusher 

plant and reuse it 

where possible 

Water contamination To dispose of 

hazardous waste in 

such a way that it 

will not impact on 

the receiving 


No contaminated 

water shall be 



No contaminated 


discharged 

Hazardous waste 

shall be disposed of 

to dedicated bins 


footprint 

No mixing of concrete or any other construction activities 

shall take place outside the demarcated area 

Contaminated runoff will be contained to the site and can 

be diverted through a sedimentation pond to remove 

suspended solids in order to reuse the water again 

Sedimentation pond must be designed to optimise the 

settlement of the suspended solids to ensure water can be 

recycled and reused 

Sludge removed from the sedimentation pond shall be 

disposed of in an appropriate manner 

Batch plants will not be located in area with steep gradient 

Clean stor<strong>mw</strong>ater shall be diverted around the area 

Water used for dust suppression and contaminated runoff 

shall be contained to the site 

Water containing high suspended solids shall be diverted 

to a settling pond from where water can be reused again 

Clean stor<strong>mw</strong>ater shall be diverted around the site 

All waste management facilities will be maintained in good 

working order 

Hazardous waste must be disposed of to dedicated bins 

Bins must have lids in order to keep rain water out 

Bins must be located in a demarcated area with an 

impermeable floor 

Runoff from the demarcated area must be contained and 

removed to dedicated containers for safe disposal by an 

approved service provider 

July 2012 7-5



Aspect 

cement bags 

etc) 

Impact Objective Performance 

indicator 

Bulk <strong>storage</strong> of 


and other 

hazardous 

substances 

Sanitation 

during 

construction 

Laydown 

areas/ 

contractors 

camp 

Water contamination To ensure that all 

hazardous 

substances are 

stored according to 

legislation 


Health concerns 


Health concerns 

To ensure that 

sufficient sanitation 

is provided 

To prevent any 

surface water 

contamination 

To provide sufficient 

laydown areas or 

contractors 

Bunded areas must 

be able to contain 

110% of stored 

volumes 

Comply with SANS 

0345 

Sanitation facilities 

shall not pollute the 

receiving 


Activities within 

contractors camp 

must be contained to 

the footprint 


contamination or 


On surface bulk <strong>storage</strong> of hydrocarbons shall be stored in 

a dedicated area which will include a bund or a drain 

where necessary to contain any spillages during the use, 

loading and off loading of the substances 

Bunded areas shall contain 110% of the stored volume 

Bund area shall be impermeable 

Bund area shall have a facility such as a valve/sump to 

drain or remove clean stor<strong>mw</strong>ater 

Contaminated water shall be <strong>pumped</strong> into a container for 

removal by an approved service provider 

Sufficient ablution facilities shall be provided to service the 

construction site 

Ablution facilities shall not be placed within 100 m of any 

drainage lines or any boreholes used for drinking water for 

human or animal consumption 

Ablution facilities shall be serviced on a regular basis by 

an approved service provider 

Contents of ablution facilities e.g. chemical toilets shall be 

disposed of to an approved Waste Water Treatment Works 

and the necessary measures shall be taken to ensure that 

it will not impact on the operations of the WWTW 

The area required for the contractors camp/ laydown shall 

must be kept to the minimum 

Laydown areas and construction camps shall not be 

established in any of the pans 

Sufficient areas shall be provided for the maintenance and 

washing of vehicles 

No washing of vehicles shall be allowed outside 

July 2012 7-6




indicator 


spillages of demarcated areas. Washing bays for vehicles and other 

equipment shall be provided with appropriate soakaways, 

will be clearly demarcated and will not be allowed to 

contaminate any surface runoff 

Refuelling of vehicles will only be allowed in designated 

areas 

Stor<strong>mw</strong>ater 

management 

Increase in runoff 

due to clearing of 

vegetation and 

topsoil resulting in 

additional water that 

must be managed 

and/or erosion 

To ensure that the 

volume of runoff 

from cleared areas / 

other impermeable 

areas is the same as 

prior to construction 

Stor<strong>mw</strong>ater shall not 

be concentrated 

and conveyed to a 

low lying area 

Water shall be 

dispersed and 

energy dissipated 

Clean and dirty 


separated 

Contaminated areas footprint shall be kept to the smallest 

possible areas and runoff water from these areas shall be 

contained and reused where possible instead of conveying 

it to a centralised point 

Clean and dirty water shall be separated wherever 

possible 

Clean water must be kept clean and not allowed to be part 

of or enter the dirty water system at any point in time 

Vegetation shall be used for filtering purposes and to 

detain the water in order to promote infiltration 

Runoff or wash water from the bulk <strong>storage</strong> areas, 

maintenance areas or any other contaminated areas shall 

pass through an oil separator prior to release or reuse of 

the water. 

Parking areas shall be designed to promote the infiltration 

of water instead of concentrating and conveying it away 

from the area. 

July 2012 7-7



7.1 OPERATIONAL PHASE 


indicator 

Pumping of 

water from the 

lower reservoir 

to the upper 

reservoir 

Aggressiveness 

of water from 

the Katse dam 

Treated effluent 

from the 

WWTW 

Increase in salinity 

due to evaporation 

Potential damage to 

the equipment due 

to aggressiveness of 

water 

Potential impact on 

the infrastructure 

To reduce impacts 

on aquatic life 

downstream of the 

upper reservoir 


July 2012 7-8 

 

To design and The aggressiveness of the water will be taken into 

consideration when designing the infrastructure 

To ensure that the 

treated effluent 

complies with the 

regulations 

Compliance of 

treated water quality 

to the standards 

WWTW shall be operated at optimal operations to ensure 

that the works comply with the standards 

The hydraulic load shall not be exceeded at any time.



8. CONCLUSIONS AND RECOMMENDATIONS 

The proposed project will provide much needed water and electricity in the Southern 

Africa region. The advantages of the project outweigh the potential negative impacts. 

The surface water quality may be impacted upon during the construction phase due 


Clearing of vegetation, 

Contamination of stor<strong>mw</strong>ater, 

Spillages of hydrocarbons/dangerous goods, 

Discharging water found in the borrow pit and tunnel with high suspended solids, 

Disposal of general waste, 

Provision of insufficient sanitation, 

The impacts associated with these activities are considered to be of a MEDIUM 

significance which can be reduced to an impact with a LOW significance with the 

implementation of mitigation measures throughout the project. 

During the operational phase water will be <strong>pumped</strong> from the Katse Dam to the 

Kobong Dam during periods when there is a low electricity demand. During periods 

of high electricity demand the water will be released from the upper reservoir to the 

lower Katse Dam to generate electricity. 

Impacts associated with the operational phase will be limited to: 

Potential increase in salinity due to the evaporation of water in the upper 

reservoir may impact on the Katse Dam. The impacts associated with this are 

foreseen to be limited when the volume of water released from the Upper dam is 

compared with the volume of the Katse Dam. 

The water quality in Katse dam is has a low buffering capacity and is considered 

to be aggressive which may impact on equipment and concrete. The pH of the 

water may also decrease with the increase of dept and therefore it will be 

important to ensure that the water abstracted from the Katse Dam to be <strong>pumped</strong> 

to the Kobong upper reservoir is withdrawn from various levels. 

The treated effluent generated from the sewage works will remain throughout the 

operational phase. The impact will be of a regional nature should the effluent be 

released which does not comply with the standards. Untreated or partially 

treated effluent may result in increase of nutrients. However the probability that 

July 2012 8-1



this will happen is not likely due the volume of effluent treated compared to the 

volume of water in the Katse Dam. The impact may be localised in the area 

where the water is released into the dam at the permanent labour camp. 

In conclusion the impacts associated with the project during the construction phase 

will be localised within the upper reaches of the Kobong River. During the operational 

phase it will not have a significant impact on the Katse Dam. 

Kabong Water Quality Draft Report V0-3 

26 July 2012

1 000 mw kobong pumped storage scheme on the katse dam ... - Iliso

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