This report was compiled by the Institute for Water Quality Studies, together with the assistance and contribution from many individuals and organisations, specifically the members of the Technical Committee. Dr P.L.Kempster compiled and edited the report.

Mr P Botes (Institute for Water Quality Studies)

Mr J Carter (formerly Institute for Water Quality Studies)

Mr H Coetzee (Council for Geoscience)

Ms K Erasmus (Institute for Water Quality Studies)

Mr D Esterhuizen (Gauteng Region, Department of Water and Sanitation)

Dr A Faanhof (Atomic Energy Corporation)

Mr D Grobler (formerly Institute for Water Quality Studies)

Mr S Guy (formerly with Council for Nuclear Safety)

Ms A Howman (Institute for Water Quality Studies)

Mr M Keet (Gauteng Region, Department of Water and Sanitation)

Dr P Kempster (Institute for Water Quality Studies)

Mr M Ludick (formerly with Gauteng Region, Department of Water and Sanitation)

Ms L Mkhondl (Institute for Water Quality Studies)

Mr T Pather (Council for Nuclear Safety)

Ms M Shai ( Institute for Water Quality Studies)

Ms M Smidt (Institute for Water Quality Studies)

Ms C Smith (Gauteng Region, Department of Water and Sanitation)

Mr S van der Woude (Council for Nuclear Safety)

Dr D Wymer (Chamber of Mines)

A note of gratitude must also be extended to the sampling teams, and the staff of the respective analytical laboratories who undertook sample analysis.

The following people participated at some point in the activities of the Committee. Please note that designations are as given by participants at the time of joining the committee, and that affiliations may have changed in the interim.

P Botes Institute for Water Quality Studies (IWQS)

J Botha Anglo Cold Limited

J Carter IWQS

H Coetzee Council for Geoscience

D Dorling Randfontein Estates Gold Mine

M Eksteen Directorate: Water Quality Management, Department of Water Affairs & Forestry (DWAF).

E Erasmus Gold Fields of South Africa.

D Esterhuizen Gauteng Region, DWAF

A Faanhof Atomic Energy Corporation (AEC)

F Fouche AEC

H Fourie Johannesburg Chamber of Industries (JCI)

A Gerber IWQS

D Grobler IWQS

S Guy Council for Nuclear Safety (CNS)

G Hoorn Free State Region, DWAF

A Howman IWQS (Chairperson)

J Katabua Rand Water (RW)

M Keet Gauteng Region, DWAF

P Kempster IWQS

M Kruger Western Transvaal Water Company

H McKay IWQS

A Mc Laren Group Water Technologist, Gold Fields of South Africa.

S Meintjies Dept Mineral and Enegy Affairs

E Meintjies RW

I Meyers JCI

S Miller Gold Fields of South Africa

J Moolman IWQS

A van der Merwe Randfontein Estates Gold Mine

B Nell Potchefstroom Municipality.

T Pather CNS

J Pieterson Western Transvaal Water Company

J Slabbert Gold Fields of South Africa.

M Smidt IWQS

L Stoch Welverdiend

H Theunissen Anglo American

D Traut Gold Fields Water

L van den Bergh Directorate: Water Quality Management, DWAF

J van der Merwe Fochville

J van der Merwe Free State Region, DWAF

S van der Woude CNS

R van Rensburg Bothaville

F Wanders University of Potchefstroom

R Webster Dept Mineral and Energy Affairs

D Wymer Chamber of Mines

P Botes - IWQS

J Carter - IWQS

H Coetzee - Council for Geoscience.

D Esterhuizen - - Gauteng Region (DWAF)

A Faanhof - AEC

D Grobler - IWQS

A Howman - IWQS

M Keet - Gauteng Region (DWAF)

P Kempster - IWQS

A Leuschner - Gold Fields Ltd., on invitation of M. Keet.

T Pather - CNS

S van der Woude - CNS

D Wymer - Chamber of Mines

TABLE OF CONTENTS

Page

Executive Summary 1

1. Introduction 3

1.1 Background 3

1.2 Aims of the Study and Strategy adopted 3

1.3 Management and Co-ordination of the programme 4

2. Monitoring Programme 4

2.1 Selection of Catchment 4

2.2 Characterisation of the Mooi River Catchment and Water Use 4

2.3 Selection of Monitoring Sites 5

2.4 Sampling Frequency and Duration 7

2.5 Geological and Radiological Characterisation of the Catchment 7

2.6 Variables Measured and Data Collected 7

2.6.1 Radionuclides 7

2.6.2 Chemical Variables 8

2.6.3 Other Data 8

2.6.4 Access to Analytical Data 8

2.7 Quality Control 9

3. Basic Radiological Considerations 9

3.1 Exposure from Natural Background Radioactivity and Medical

Procedures 9

3.2 Exposure Pathways 10

3.3 Health Effects of Ionizing Radiation 10

3.4 Radiation Protection Principles and the System of Radiation Protection 11

3.5 Calculation of Dose for the Drinking Water Ingestion Pathway 11

3.5.1 Dose Conversion Factor 12

3.5.2 Activity Concentration 12

4. Drinking Water Quality Considerations 13

5. Discussion of Results 16

5.1 Annual Dose within the Mooi River Catchment for the Drinking Water

Exposure Route 16

5.2 Discussion of Predominance and Uranium 17

5.3 Annual Radiation Dose from Background Radiation Levels in Water 18

5.4 Relationship between Gross Alpha Activity and the Annual Dose 19

5.5 Relationship between Uranium Concentration and the Annual Dose 18

5.6 Verification of Dose Calculations 19

5.7 Possible Uncertainties in Dose Calculations 20

5.8 Suspended Solids 21

5.9 Chemical Results: Sulphate 21

6. The Gauteng Regional Office Water Quality Management Strategy for the

Mooi River 21

6.1 Source Directed Controls 21

6.2 Water User Assessments 22

6.3 Actions taken at Sites 7a and 12 22

6.4 Monitoring 22

7. Conclusions and Recommendations 23

7.1 General Conclusions 23

7.2 Municipal Water Supplies 23

7.3 Indicators of Radiological Water Quality 23

7.4 Suspended Solids 24

7.5 Guideline Development 24

7.6 Recommendations 24

8. References 26

Appendix 1: Water Users in the Mooi River Catchment A1-1

Appendix 2: Methods of Analysis for Radionuclides A2-1

Appendix 3: Sampling and IWQS Analytical Procedures A3-1

Appendix 4: Information on Decay Chains A4-1

Appendix 5: Inter laboratory Split Sample Quality Control A5-1

Appendix 6: Quality Control and Validation done in the AEC Laboratory A6-1

Appendix 7: Evaluation of dose from the drinking water pathway as opposed

to other possible pathways of exposure A7-1

Appendix 7A: Calculations Involving Irrigation A7A-1

Appendix 7B: Significance of dose to drinking water pathway relative to that

of other ingestion pathways A7B-1

Appendix 8: Method One (IWQS), used for dose calculation A8-1

Appendix 9: Method Two (AEC), used for independent dose verification A9-1

Appendix 10: Estimation of possible uncertainties A10-1