THE IMPACT OF HISTORICAL METAL MINING

ON THE RIVER SWALE CATCHMENT,

NORTH YORKSHIRE, U.K.

IAN DENNIS

UNIVERSITY OF WALES, ABERYSTWYTH

JULY 2005

Abstract

i

ABSTRACT

This investigation examines the impact of historical metal mining on the River Swale

catchment, North Yorkshire, U.K. Approximately 550,000 tonnes of Pb were extracted

from mines in the Swale catchment during the eighteenth and nineteenth centuries.

Mining and processing operations were relatively inefficient, leading to the discharge of

large quantities of metal-rich sediment into the fluvial system. The primary aim of this

thesis is to assess the physical and chemical impacts of the discharge of metals from

historical mining activities on the River Swale catchment as a whole. The dispersal,

storage and transfer of metal-rich sediment in formerly mined tributaries, floodplain and

flood sediments are evaluated, and the environmental consequences of mining are

assessed.

A detailed geochemical survey of the River Swale catchment indicates that channel and

floodplain sediments within formerly mined tributaries exhibit extremely high

concentrations of Pb, Zn and Cd. Similar enrichment is observed in floodplain sediments

from throughout the catchment, suggesting that large volumes of material have been

transported from the tributaries and deposited on the Swale floodplain. Evidence from

contemporary flood sediments suggests that considerable quantities of metal-rich sediment

continue to be cycled through the system almost 100 years after the cessation of mining

operations. Sediment budgeting suggests that 32,000 tonnes of Pb remain stored in

formerly mined tributaries, with a further 123,000 tonnes stored in the Swale floodplain.

Combined storage represents more than half of the total Pb that is likely to have been

released during mining operations, suggesting that the impacts of metal mining are

extremely long-lasting. Concentrations of Pb, Zn and Cd in tributary, floodplain and flood

sediments greatly exceed current U.K. environmental quality guidelines and catchment-

specific background values. Metal enrichment as a result of historical mining operations

could therefore pose a serious and long-term threat to plant and animal health in the Swale

catchment.

Acknowledgements

ii

ACKNOWLEDGEMENTS

First, I would like to thank my supervisors, Dr. Tom Coulthard, Professor Mark Macklin,

and Dr. Paul Brewer, for their advice and help with all aspects of this thesis. Grateful

thanks are also extended to Dr. Bill Perkins, Dr. Nick Pearce, Lorraine Hill, Lorraine

Morrison and Wynne Ebenezer, without whose invaluable guidance geochemical analyses

would have proved impossible! Ian Gulley and Anthony Smith are also thanked for their

assistance in producing several of the figures included in this thesis. Dr. John Ridgway is

thanked for the provision of BGS G-Base data for the Swale catchment, and Dr. Sean

Longfield and Victoria Townend of the Environment Agency are thanked for providing

flow data from the Catterick Bridge gauging station. Thanks are also extended to the

landowners of the River Swale catchment, without whose co-operation this investigation

would have been impossible. Eric Johnstone, Phillippa Noble, Anna Jones, Graham Bird,

Simon Gittins, Jonathan Turner and Liz Young are all thanked for their helpful discussions

and much appreciated assistance with field work, and Marco van de Wiel is thanked for

his advice with all things mathematical and computational.

I would also like to thank all my friends here in Aberystwyth for their assistance with ‘rest

and recuperation’, especially Eric, Simon, Zenobia, Natalie, and Graham. Finally, deepest

thanks are extended to my parents, Nicola, and of course Clare, who have helped me

through my studies with their support and encouragement.

Ordnance Survey Landline data appears in Figures 4.6, 5.3 – 5.14 and 7.2.

© Crown Copyright Ordnance Survey. An EDINA Digimap/ JISC supplied service.

Contents

iii

CONTENTS

ABSTRACT i

ACKNOWLEDGEMENTS ii

TABLE OF CONTENTS iii

LIST OF FIGURES x

LIST OF TABLES xiv

LIST OF PLATES xvi

CHAPTER 1

INTRODUCTION: METALS IN FLUVIAL SEDIMENTS

1.1. Introduction 1

1.2. Metals in fluvial sediments: a review 3

1.2.1. Introduction 3

1.2.2. The behaviour of metals in fluvial sediments 3

1.2.3. Metal transport in fluvial sediments 6

1.2.4. Metal storage in fluvial sediments 9

1.2.5. Remobilisation of metals 11

1.2.6. The geomorphological impacts of metal mining 12

1.2.7. Summary: Metals in fluvial sediments 15

1.3. Thesis background and aims 15

CHAPTER 2

STUDY AREA: THE RIVER SWALE CATCHMENT AND ITS MINING

HISTORY

2.1. The River Swale catchment 18

2.1.1. General characteristics 18

Contents

iv

2.1.2. Catchment geology 20

2.1.3. Mineralisation 22

2.1.4. Catchment geochemistry 24

2.1.5. Glacial history and Holocene development 25

2.1.6. Fluvial geomorphology 25

2.2. Metal mining in the Swale catchment 31

2.2.1. The history of lead mining in Swaledale 31

2.2.2. Mining and processing techniques 32

2.2.3. Mining production records 39

2.3. The impact of metal mining on the River Swale system 42

2.3.1. The potential impacts of mining and processing 42

2.3.2. Investigations of floodplain contamination 43

2.3.2.1. Upland contamination patterns 43

2.3.2.2. Piedmont contamination patterns 44

2.3.2.3. Lowland contamination patterns 45

2.3.2.4. Summary of catchment-scale patterns 45

2.3.3. Investigations of channel sediment contamination 46

2.3.4. Summary and required research 48

CHAPTER 3

GEOCHEMICAL CHARACTERISATION OF FLUVIAL SEDIMENTS IN THE

SWALE CATCHMENT

3.1. Introduction 50

3.2. Laboratory methods 51

3.2.1. Particle size selection 51

3.2.2. Initial sample preparation 51

3.2.3. Digestion procedure 52

3.2.4. ICP-MS analysis 54

3.3. Analytical Quality Control 55

3.3.1. Approaches to AQC 55

3.3.2. Quality control during sample collection 55

3.3.3. Quality control during sample preparation and analysis 56

3.3.4. Data quality: AQC results 57

3.4. Summary 58

Contents

v

CHAPTER 4

THE IMPACT OF METAL MINING ON HEADWATER TRIBUTARIES OF THE

RIVER SWALE: THE GUNNERSIDE BECK CATCHMENT

4.1. Introduction 59

4.2. Study Area: Gunnerside Beck 60

4.2.1. General characteristics 60

4.2.2. Catchment geology and mineralisation 60

4.2.3. Fluvial geomorphology 63

4.3. Mining in Gunnerside Beck 68

4.3.1. Mining history 68

4.3.2. The Blakethwaite mines 68

4.3.3. The Lownathwaite mines 70

4.3.4. The Old Gang mines 73

4.3.5. Sir Francis Level 74

4.3.6. Summary: The legacy of mining in Gunnerside Beck 75

4.4. The impact of mining on catchment geochemistry 76

4.4.1. Introduction 76

4.4.2. Methods 76

4.4.3. Patterns of metal dispersal in mine waste 76

4.4.4. Patterns of metal dispersal in floodplain sediments 80

4.4.5. Patterns of metal dispersal in channel sediments 87

4.4.6. Grain size partitioning 93

4.4.7. Summary: The geochemical legacy of mining in Gunnerside Beck 95

4.5. The impact of mining on fluvial geomorphology 98

4.5.1. Introduction 98

4.5.2. Morphological changes attributable to mining 98

4.5.3. Morphological changes since the cessation of mining 101

4.5.4. Summary: The geomorphological legacy of mining in Gunnerside Beck 103

4.7. Conclusion 103

CHAPTER 5

METAL DISTRIBUTION IN FLOODPLAIN SEDIMENT

5.1. Introduction 105

5.2. Methods 106

Contents

vi

5.3. Metal distribution patterns 109

5.3.1. Introduction 109

5.3.2. Downstream metal distribution patterns 110

5.3.3. Lateral metal distribution patterns 110

5.3.3.1. Hartlakes 110

5.3.3.2. Reeth 113

5.3.3.3. Hudswell 113

5.3.3.4. Brompton-on-Swale 116

5.3.3.5. Great Langton 116

5.3.3.6. Morton Flatts 118

5.3.3.7. Fairholme 120

5.3.3.8. Maunby 121

5.3.3.9. Holme 122

5.3.3.10. Eldmire 123

5.3.3.11. Thornton Manor 124

5.3.3.12. Myton-on-Swale 124

5.3.3.13. Additional floodplain cores 124

5.3.4. Summary: Metal distribution patterns in floodplain sediments 127

5.4. Controls on metal distribution 127

5.4.1. Introduction 127

5.4.2. Longitudinal distribution patterns 128

5.4.3. Lateral distribution patterns 131

5.4.4. Metal distribution patterns with depth 140

5.4.5. Summary: Controls on metal distribution in floodplain sediments 140

5.5. Conclusion 141

CHAPTER 6

PATTERNS OF METAL DISTRIBUTION IN CONTEMPORARY FLOOD

SEDIMENTS

6.1. Introduction 142

6.2. Methods 143

6.2.1. Recent floods in the Swale catchment 143

6.2.2. Flood sediment: sampling and analysis 144

6.2.3. Measuring overbank metal deposition 148

Contents

vii

6.3. Metal distribution patterns in flood sediments 149

6.3.1. Introduction 149

6.3.2. October-December 2000 floods 150

6.3.2.1. Channel-edge sediment 150

6.3.2.2. Overbank sediment 150

6.3.3. November-December 2001 floods 153

6.3.3.1. Channel-edge sediment 153

6.3.3.2. Overbank sediment 153

6.3.4. January-February 2002 floods 155

6.3.4.1. Channel-edge sediment 155

6.3.4.2. Overbank sediment 157

6.3.5. Grain size partitioning in flood sediments 157

6.3.6 Metal deposition on the River Swale floodplain 161

6.3.7. Summary: Metal distribution patterns in flood sediments 164

6.4. Controls of downstream metal concentrations in flood sediments 168

6.4.1. Introduction 168

6.4.2. Downstream decline of metals on flood sediments 168

6.4.3. Sediment inputs 168

6.4.4. Geomorphological controls 172

6.4.5. The influence of flood magnitude on metal concentrations 175

6.4.6. Summary: Controls of downstream metal distribution in flood sediments 178

6.5. Conclusion 178

CHAPTER 7

METAL STORAGE IN THE RIVER SWALE CATCHMENT

7.1. Introduction 180

7.2. Metal storage in formerly mined tributaries 181

7.2.1. Introduction 181

7.2.2. Methods: Estimating metal storage in Gunnerside Beck 181

7.2.3. Metal storage in Gunnerside Beck 183

7.2.4. Potential metal storage in tributary sediments 188

7.2.5. Summary: Metal storage in tributary sediments 188

7.3. Metal storage in floodplain sediments 191

7.3.1. Introduction 191

Contents

viii

7.3.2. Methods: Estimating floodplain metal storage 191

7.3.3. Metal storage in the River Swale floodplain 192

7.3.4. Summary: Metal storage in floodplain sediments 198

7.4. Metal storage and fluxes in the River Swale catchment 199

7.5. Conclusion 201

CHAPTER 8

ASSESSING THE ENVIRONMENTAL IMPACT OF MINING IN THE SWALE

CATCHMENT

8.1. Introduction 202

8.2. Assessment using environmental quality guidelines 203

8.2.1. Environmental quality guidelines in the U.K 203

8.2.2. Comparison with U.K guidelines 206

8.2.3. Limitations of existing guidelines 212

8.3. Assessing using background concentrations 213

8.3.1. Approaches to background determination 213

8.3.2. Determining background metal concentrations in the Swale catchment 215

8.3.3. Comparison with background concentrations 221

8.3.4. Limitations of estimating background concentrations 225

8.4. Environmental impacts of metal enrichment 227

8.4.1. Implications of metal enrichment in fluvial sediments 227

8.4.2. Potential management strategies 229

8.5. Conclusion: The environmental impact of metal mining 231

CHAPTER 9

CONCLUSIONS

9.1. Summary of findings 233

9.1.1. Metals in tributary sediments 233

9.1.2. Metals in floodplain sediments 234

9.1.3. Metals in flood sediments 234

9.1.4. Metal storage in the Swale catchment 235

9.1.5. The environmental impact of mining 235

9.2. Overall conclusions 236

Contents

ix

9.3. Implications 236

9.4. Recommendations for further research 238

BIBLIOGRAPHY 240

APPENDIX 1: GUNNERSIDE BECK DATA 257

APPENDIX 2: FLOODPLAIN SEDIMENT DATA 261

APPENDIX 3: FLOOD SEDIMENT DATA 267

List of figures

x

LIST OF FIGURES

CHAPTER 2

Figure 2.1: The River Swale catchment, showing drainage network and major

tributaries

19

Figure 2.2: Geology of the Swale catchment 21

Figure 2.3: The distribution of mineral veins in the Swale catchment 22

Figure 2.4: Geomorphological characteristics of the River Swale 26

Figure 2.5: Location and output of Pb mines in Swaledale 32

Figure 2.6: The ore dressing process employed in Swaledale Pb mines 35

Figure 2.7: Location of smelters and dressing floors in Swaledale 38

Figure 2.8: Total Pb production by tributary 41

Figure 2.9: Metal contamination in River Swale channel sediments 47

CHAPTER 3

Figure 3.1: Flow chart detailing the HNO3 digestion procedure used in this

investigation

53

CHAPTER 4

Figure 4.1: Map of the Gunnerside Beck catchment, showing drainage network,

relief, and location of mines, dressing floors and smelters

61

Figure 4.2: Major mineral veins in the Gunnerside catchment 62

Figure 4.3: Geomorphological characteristics of Gunnerside Beck 64

Figure 4.4: The Blakethwaite lead mines 69

Figure 4.5: The Lownathwaite and Old Gang mines 71

Figure 4.6: Sediment sample sites in Gunnerside Beck 77

Figure 4.7: Pb, Zn and Cd concentrations in 2000-63 µm Gunnerside Beck mine

spoil

81

Figure 4.8: Pb, Zn and Cd concentrations in <63 µm Gunnerside Beck mine spoil 82

List of figures

xi

Figure 4.9: Pb, Zn and Cd concentrations in 2000-63 µm Gunnerside Beck

floodplain sediments

83

Figure 4.10: Pb, Zn and Cd concentrations in <63 µm Gunnerside Beck floodplain

sediments

84

Figure 4.11: Floodplain contamination schematic 88

Figure 4.12: Pb, Zn and Cd concentrations in 2000-63 µm Gunnerside Beck

channel sediments

89

Figure 4.13: Pb, Zn and Cd concentrations in <63 µm Gunnerside Beck channel

sediments

90

Figure 4.14: Grain size characteristics of Gunnerside Beck floodplain sediments,

channel sediments and mine spoil

94

Figure 4.15: Gunnerside Beck 2000-63 µm concentrations, waste inputs and

catchment characteristics

96

Figure 4.16: Gunnerside Beck <63 µm concentrations, waste inputs and catchment

characteristics

97

CHAPTER 5

Figure 5.1: Floodplain sediment study sites in the River Swale catchment 108

Figure 5.2: Downstream trends in metal dispersal 111

Figure 5.3: Floodplain metal concentrations and surface topography at Hartlakes 112

Figure 5.4: Floodplain metal concentrations and surface topography at Reeth 114

Figure 5.5: Floodplain metal concentrations and surface topography at Hudswell 115

Figure 5.6: Floodplain metal concentrations and surface topography at

Brompton-on-Swale

117

Figure 5.7: Floodplain metal concentrations and surface topography at Great

Langton

118

Figure 5.8: Floodplain metal concentrations and surface topography at Morton

Flatts

119

Figure 5.9: Floodplain metal concentrations and surface topography at Fairholme 120

Figure 5.10: Floodplain metal concentrations and surface topography at Maunby 121

Figure 5.11: Floodplain metal concentrations and surface topography at Holme 122

Figure 5.12: Floodplain metal concentrations and surface topography at Eldmire 123

Figure 5.13: Floodplain metal concentrations and surface topography at Thornton

Manor

125

List of figures

xii

Figure 5.14: Floodplain metal concentrations and surface topography at Myton-

on-Swale

126

Figure 5.15: Pb concentration in floodplain and tributary sediments, and

geomorphological characteristics

129

Figure 5.16: Floodplain metal concentrations and elevation 134

Figure 5.17: Simulated inundation frequency and floodplain metal concentrations

at Reeth

137

Figure 5.18: Simulated inundation frequency and floodplain metal concentrations

at Brompton-on-Swale

138

CHAPTER 6

Figure 6.1: Mean, minimum and maximum daily discharge at Catterick Bridge

gauging station

145

Figure 6.2: Map of the River Swale catchment, showing flood sediment sampling

sites and the location of major tributaries

146

Figure 6.3: Pb, Zn and Cd concentrations in 2000 channel-edge flood sediment 151

Figure 6.4: Pb, Zn and Cd concentrations in 2000 overbank flood sediment 152

Figure 6.5: Pb, Zn and Cd concentrations in 2001 channel-edge flood sediment 154

Figure 6.6: Pb, Zn and Cd concentrations in 2001 overbank flood sediment 155

Figure 6.7: Pb, Zn and Cd concentrations in 2002 channel-edge flood sediment 156

Figure 6.8: Pb, Zn and Cd concentrations in 2002 overbank flood sediment 158

Figure 6.9: Grain size characteristics of channel-edge flood sediments 159

Figure 6.10: Grain size characteristics of overbank flood sediments 160

Figure 6.11: Overbank sediment and metal deposition along the River Swale 162

Figure 6.12: Pb concentrations in 2000, 2001 and 2002 flood sediments 165

Figure 6.13: Zn concentrations in 2000, 2001 and 2002 flood sediments 166

Figure 6.14: Cd concentrations in 2000, 2001 and 2002 flood sediments 167

Figure 6.15: Pb concentrations in channel-edge flood sediment, tributaries and

floodplain sediment, and geomorphological characteristics

170

Figure 6.16: Pb concentrations in overbank flood sediment, tributaries and

floodplain sediment, and geomorphological characteristics

171

List of figures

xiii

CHAPTER 7

Figure 7.1: Estimating metal storage in tributary and floodplain sediments 182

Figure 7.2: Floodplain Pb storage in Gunnerside Beck 184

Figure 7.3: Likely maximum extent of floodplain metal storage in the Swale

catchment

194

CHAPTER 8

Figure 8.1: Swale tributary, floodplain and flood sediments and U.K.

environmental quality guidelines for Pb

208

Figure 8.2: Swale tributary, floodplain and flood sediments and U.K.

environmental quality guidelines for Pb

209

Figure 8.3: Swale tributary, floodplain and flood sediments and U.K.

environmental quality guidelines for Pb

210

Figure 8.4: Cumulative frequency curves for Pb, Zn and Cd 218

Figure 8.5: Recalculated background population (F’) for Pb, Zn and Cd 220

Figure 8.6: Swale tributary, floodplain and flood sediments and background

concentrations for Pb

222

Figure 8.7: Swale tributary, floodplain and flood sediments and background

concentrations for Pb

223

Figure 8.8: Swale tributary, floodplain and flood sediments and background

concentrations for Pb

224

List of tables

xiv

LIST OF TABLES

CHAPTER 2

Table 2.1: Flood frequency and magnitude in the Yorkshire Ouse basin,

reconstructed from instrumental records

28

Table 2.2: Flood frequency and magnitude in the Yorkshire Ouse basin,

reconstructed from flood deposits

28

Table 2.3: Recorded and estimated lead production 40

Table 2.4: Recorded production of lead metal and concentrates in the North

Swaledale Mineral Belt

40

Table 2.5: Recorded production of lead metal and concentrates in the South

Swaledale mining zone

40

CHAPTER 3

Table 3.1: Sampling and analytical coefficient of variation data for tributary,

floodplain and flood sediments

57

CHAPTER 4

Table 4.1: Multiple regression results: The relationship between metal

concentrations and geomorphological parameters in Gunnerside Beck

floodplain sediments

86

Table 4.2: Multiple regression results: The relationship between metal

concentrations and geomorphological parameters in Gunnerside Beck

channel sediments

92

CHAPTER 5

Table 5.1: Study reach characteristics 107

Table 5.2: Multiple regression results: The relationship between floodplain metal

concentrations and geomorphological parameters

130

List of tables

xv

CHAPTER 6

Table 6.1: Multiple regression results: The relationship between metal

concentrations in channel-edge flood sediments and geomorphological

parameters

173

Table 6.2: Multiple regression results: The relationship between metal

concentrations in overbank flood sediments and geomorphological

parameters

174

CHAPTER 7

Table 7.1: Estimated storage of Pb in formerly mined tributaries 189

Table 7.2: Estimated storage of Pb in floodplain sediments 193

CHAPTER 8

Table 8.1: U.K. metal concentration guidelines for Pb, Zn and Cd 205

Table 8.2: Percentage failure of environmental quality guidelines 207

Table 8.3: Descriptive statistics for fluvial sediments from the Swale catchment 216

Table 8.4: Background concentrations for Pb, Zn and Cd in the Swale catchment 221

Table 8.5: Percentage of samples exceeding background metal concentrations 225

List of plates

xvi

LIST OF PLATES

CHAPTER 2

Plate 2.1: North Hush and Priscilla Level, Gunnerside Beck 34

Plate 2.2: Bouse teams, Old Gang Company dressing floor, Sir Francis Level,

Gunnerside Beck

34

Plate 2.3: Water-powered crusher, Bunton Level, Gunnerside Beck 36

Plate 2.4: Surrender smelt mill, Barney Beck 39

CHAPTER 4

Plate 4.1: The upper reaches of Gunnerside Beck 65

Plate 4.2: Floodplain deposits downstream of the Old Gang and Lownathwaite

mines

65

Plate 4.3: Floodplain deposits and the AD Company dressing floor at Sir Francis

Level

66

Plate 4.4: Blakethwaite smelter and the Blind Gill – Gunnerside Beck confluence 70

Plate 4.5: Sun Hush and North Hush 72

Plate 4.6: Bouse teams and the remains of a crushing mill at Bunton Level

dressing floor

74

Plate 4.7: Channel braiding upstream of the Old Gang and Lownathwaite hushes 100

Plate 4.8: Braid bars and chutes downstream of the Old Gang and Lownathwaite

hushes

100

Plate 4.9: Eroding bank section showing mining-related floodplain development 101

CHAPTER 6

Plate 6.1: Overbank sediments deposited in January-February 2002 147