Title Details

Preface xi

Lewis Clark (1937–2004): an appreciation xiii

Acknowledgements xv

1 Introduction 1

1.1 Wells and boreholes 1

1.2 Groundwater occurrence 7

1.2.1 Aquifers, aquicludes and aquitards 7

1.2.2 Porosity and aquifer storage 12

1.3 Groundwater flow 16

1.3.1 Darcy’s equation 16

1.3.2 General equations of groundwater flow 20

1.3.3 Radial flow to wells 25

2 Groundwater investigations for locating well sites 31

2.1 Desk studies 34

2.2 Field reconnaissance 38

2.3 Well survey 40

2.4 Geophysical surveys 42

2.4.1 Electrical resistivity 43

2.4.2 Electromagnetics 49

2.5 Drilling investigations 53

2.6 Groundwater resources assessment 61

2.6.1 Inflow estimation: direct recharge 61

2.6.2 Inflow estimation: indirect recharge 66

2.6.3 Aquifer response analysis 66

2.6.4 Outflow estimation 68

2.6.5 Catchment water balance and modelling 69

2.7 Groundwater quality 71

2.7.1 Introduction 71

2.7.2 Chemical composition of groundwater 71

2.7.3 Groundwater for potable supply 73

2.7.4 Groundwater for irrigation 79

2.8 Pollution risk assessment and prevention 81

2.8.1 Groundwater vulnerability 81

2.8.2 Wellhead protection areas 83

2.8.3 Estimating the pollution risk for a new well site 88

2.9 Planning the well scheme 90

3 An introduction to well and borehole design 93

3.1 Drilled wells 93

3.1.1 General design principles 93

3.1.2 Wells in crystalline aquifers 98

3.1.3 Wells in consolidated aquifers 101

3.1.4 Wells in unconsolidated aquifers 106

3.1.5 Economic considerations in well design 110

3.2 Hand-dug wells 111

3.2.1 Design for yield 111

3.2.2 Design for health 115

3.3 Infiltration galleries 118

3.4 Radial collector wells 123

3.5 Observation boreholes 124

3.6 Exploration boreholes 127

3.7 Pump selection 128

3.7.1 Vertical turbine pumps 132

3.7.2 Electrical submersible pumps 133

3.7.3 Motorized suction pumps 135

3.7.4 Helical rotor pumps 136

3.7.5 Hand pumps 138

4 Specific issues in well and borehole design 143

4.1 Choice of construction materials 143

4.1.1 Strength 144

4.1.2 Jointing system 145

4.1.3 Durability 145

4.1.4 Chemical inertness 147

4.1.5 Standards 147

4.2 Casing 149

4.2.1 Steel casing 149

4.2.2 Plastic and fibreglass casing 150

4.3 Screen 151

4.3.1 Slot design and open area 152

4.3.2 Slot width 154

4.4 Gravel pack design 155

4.4.1 Natural gravel pack 155

4.4.2 Artificial gravel pack 156

4.5 Hydraulic design 160

4.5.1 Partial penetration effects 162

4.5.2 Gravel pack loss 165

4.5.3 Screen entrance loss 165

4.5.4 Well upflow losses 168

4.6 Economic optimization of well design 174

4.6.1 General principles 174

4.6.2 Example 175

5 Well and borehole construction 181

5.1 Percussion drilling 186

5.1.1 Drilling in hard-rock formations 188

5.1.2 Drilling in soft, unstable formations 189

5.1.3 Light-percussion drilling 194

5.2 Rotary drilling 195

5.2.1 Direct circulation rotary 195

5.2.2 Fluids used in direct circulation rotary drilling 201

5.2.3 Reverse circulation 206

5.2.4 Top-hole and down-the-hole hammer drilling 209

5.2.5 Borehole testing during drilling 212

5.2.6 Methods of casing and screen installation 215

5.3 Auger drilling 217

5.4 Jetting 217

5.5 Driving of well-points 219

5.6 Manual construction 220

5.7 Well development 223

5.7.1 Well and aquifer damage 223

5.7.2 Developing the well 224

5.7.3 Developing the aquifer around the well 224

5.7.4 Methods of development 226

5.7.5 Disinfecting the well 233

5.8 Wellhead completion 235

6 Formation sampling and identification 241

6.1 Observing the drilling process 241

6.1.1 Observing the drilling process in hard-rock aquifers 244

6.2 Collecting formation samples 245

6.2.1 Disturbed formation sampling 247

6.2.2 Undisturbed formation sampling 252

6.3 Description and analysis of drilling samples 257

6.3.1 Characterizing disturbed samples 258

6.3.2 Characterization of representative samples 258

6.3.3 Characterization of undisturbed samples 265

6.4 Downhole geophysical logging 267

6.4.1 The geophysical logging package 267

6.4.2 Organizing a geophysical logging mission 271

6.4.3 On arriving on site 275

6.4.4 Formation logs 275

6.4.5 Fluid logs 282

6.4.6 Well construction logs 285

6.5 Downhole geophysical imaging 286

6.6 Preparing a composite well log 290

7 Well and borehole testing 293

7.1 Objectives of test pumping 293

7.1.1 Well performance 293

7.1.2 Water quality 294

7.1.3 Sustainability 295

7.1.4 Environmental impacts 296

7.1.5 Aquifer properties 296

7.2 Planning a well pumping test 297

7.2.1 Before starting 297

7.2.2 When to test pump 299

7.2.3 Consents and permissions 300

7.2.4 Equipment 302

7.2.5 The observation network 307

7.2.6 Recording of data 311

7.3 Types of pumping test 313

7.3.1 Dimension pumping 313

7.3.2 The step test 314

7.3.3 Medium- to long-term (constant rate) test 314

7.3.4 Recovery test 316

7.4 Analysis of test pumping data from single wells 317

7.4.1 Fundamentals 317

7.4.2 The misuse of test pumping analysis 317

7.4.3 Well performance – the step test 320

7.4.4 Steady-state analyses 323

7.4.5 Time-variant analysis 326

7.4.6 Analysis of recovery tests 333

7.5 Multiple wells 334

7.5.1 Steady-state analysis of multiple pumping wells 334

7.5.2 Time-variant analysis of multiple wells 335

7.5.3 Application of the Cooper–Jacob approximation to multiple wells 335

7.6 The shape of the yield–drawdown curve: deviations from the ideal response 336

7.6.1 A noninfinite aquifer: presence of an impermeable barrier 336

7.6.2 Recharge during a pumping test 338

7.6.3 Unconfined aquifers: delayed yield 341

7.7 Interpretation of pumping and recovery test data in hard-rock aquifers 343

7.7.1 High yielding hard-rock wells 344

7.7.2 Low yielding hard-rock wells 345

7.7.3 Sustainable yield of hard-rock wells 349

7.8 Single borehole tests: slug tests 349

7.8.1 Slug tests 349

7.8.2 Packer testing 351

7.9 Test pumping a major well field: the Gatehampton case study 352

7.10 Record-keeping 355

8 Groundwater sampling and analysis 357

8.1 Water quality parameters and sampling objectives 359

8.1.1 Master variables 359

8.1.2 Main physicochemical parameters 360

8.1.3 Major ions 361

8.1.4 Drinking water 362

8.1.5 Water for agricultural and industrial purposes 364

8.1.6 Pollution-related parameters 364

8.1.7 Indicator parameters 364

8.1.8 Microbiological quality and indicator parameters 367

8.2 Field determinations 371

8.2.1 The purpose of field determinations 371

8.2.2 Downhole sondes and throughflow cells 372

8.2.3 Field kits for other parameters 373

8.2.4 Emergency water supply 375

8.3 Collecting water samples from production wells 377

8.3.1 The sample line 377

8.3.2 When to sample: well testing 379

8.3.3 When to sample: production wells 381

8.4 Collecting water samples from observation boreholes 381

8.4.1 Preparation for sampling 381

8.4.2 Bailers and depth samplers 383

8.4.3 Simple pumps 385

8.4.4 Submersible pumps 386

8.4.5 Other pumps 386

8.4.6 Sampling at specific depths 388

8.4.7 Sampling for non-aqueous phase liquids 390

8.5 Sample filtration, preservation and packaging 393

8.5.1 Sampling order 395

8.5.2 Physicochemical parameters 395

8.5.3 Microbial parameters 396

8.5.4 Inorganic parameters: acidification and filtration 397

8.5.5 Inorganic parameters: sampling 400

8.5.6 Organic parameters 400

8.6 Packing and labelling samples 403

8.7 Quality control and record keeping 405

8.8 Sample analysis 409

8.9 Hydrochemical databases 411

9 Well monitoring and maintenance 413

9.1 Factors affecting well system performance 414

9.1.1 Physical processes 414

9.1.2 Chemical processes 415

9.1.3 Microbiological processes 421

9.1.4 Well design and construction 423

9.1.5 Well system operation 423

9.2 Monitoring well system performance 424

9.2.1 Monitoring well performance 426

9.2.2 Well inspection tools 433

9.2.3 Pump performance 434

9.2.4 Water quality monitoring 437

9.2.5 Monitoring microbial processes 438

9.3 Well maintenance and rehabilitation measures 439

9.4 Well decommissioning 445

10 Well and borehole records 449

10.1 Well archives 449

10.2 Operational well databases 450

Appendix 1 Units and conversion tables 459

Appendix 2 World Health Organization drinking water guidelines 463

Appendix 3 FAO irrigation water quality guidelines 469

References 471

Index 489

“Overall, this book is a valuable addition to the literature and a useful asset to any hydrogeologist that is involved in the design and construction of water wells, their operation and rehabilitation. It is also strongly recommended for graduate and undergraduate students of hydrogeology and others with an interest in water well operations."  (Hydrogeology Journal, 9 January 2011)

…lucid, comprehensive and beautifully-written...  would recommend every aspiring and practicing hydrogeologist should buy it and thumb it to pieces.’ (Quarterly Journal of Engineering Geology and Hydrogeology, May 2007)