ASCE Manuals and Reports on Engineering Practice No. 127 Hydraulics of Wells Design, Construction, Testing, and Maintenance of Water Well Systems Prepared by the Task Committee on Hydraulics of Wells of the Groundwater Hydrology Technical Committee of the Groundwater Council and Watershed Council of the Environmental and Water Resources Institute of the American Society of Civil Engineers Edited by Nazeer Ahmed , Ph.D., P.E.; Stewart W. Taylor , Ph.D., P.E.; and Zhuping Sheng , Ph.D., P.E. Library of Congress Cataloging-in-Publication Data Hydraulics of wells : design, construction, testing, and maintenance of water well systems / prepared by the Task Committee on Hydraulics of Wells of the Groundwater Hydrology Technical Committee of the Groundwater Council and Watershed Council of the Environmental and Water Resources Institute of the American Society of Civil Engineers ; edited by Nazeer Ahmed, P.E., Stewart W. Taylor, Ph.D., P.E., and Zhuping Sheng, Ph.D., P.E. pages cm – (ASCE manuals and reports on engineering practice; No. 127) Includes bibliographical references and index. ISBN 978-0-7844-1273-2 (print : alk. paper) – ISBN 978-0-7844-7826-4 (ebook) 1. Wells. 2. Hydrogeology. 3. Hydrology. I. Ahmed, Nazeer. II. Environmental and Water Resources Institute (U.S.). Task Committee on Hydraulics of Wells. TD405.H93 2014 628.1’14–dc23 2013047661 Published by American Society of Civil Engineers 1801 Alexander Bell Drive Reston, Virginia, 20191-4382 www.asce.org/bookstore | ascelibrary.org Any statements expressed in these materials are those of the individual authors and do not necessarily represent the views of ASCE, which takes no responsibility for any statement made herein. No reference made in this publication to any specifi c method, product, process, or service constitutes or implies an endorsement, recommendation, or warranty thereof by ASCE. 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A list of available Manuals of Practice can be found at http://www .asce.org/bookstore. This page intentionally left blank CONTENTS CONTRIBUTORS ...................................................................................... xi PREFACE ..................................................................................................... xvii INTRODUCTION ...................................................................................... xix 1. FUNDAMENTAL CONCEPTS OF GROUNDWATER FLOW ....................................................................................................... 1 Bruce L. Jacobs 1.1 General ............................................................................................ 1 1.2 Hydrologic Cycle .......................................................................... 2 1.3 Porous Media ................................................................................. 3 1.4 Aquifer Systems ............................................................................ 5 1.5 Aquifer Storage ............................................................................. 11 1.6 Darcy Equation .............................................................................. 15 1.7 Basic Equations of Groundwater Flow ..................................... 24 1.8 Aquifer Flow .................................................................................. 26 1.9 Summary ........................................................................................ 29 1.10 Solved Design Example 1 ............................................................ 30 1.11 Solved Design Example 2 ............................................................ 31 1.12 References ....................................................................................... 34 2. HEAD LOSSES, TOTAL DRAWDOWN, TOTAL DYNAMIC HEAD, AND EFFICIENCY OF WATER-WELL SYSTEMS .......... 37 Nazeer Ahmed and James A. Cardle 2.1 General ............................................................................................ 37 2.2 Head Loss in the Suction Pipe .................................................... 55 2.3 Head Loss in the Delivery Pipe .................................................. 56 2.4 Total Dynamic Head ..................................................................... 58 2.5 Effi ciency of Water-Well Systems ............................................... 65 2.6 Solved Design Example 1 ............................................................ 72 v vi CONTENTS 2.7 Solved Design Example 2 ............................................................ 76 2.8 Solved Design Example 3 ............................................................ 79 2.9 References ....................................................................................... 81 3. DESIGN OF WATER WELLS ............................................................. 83 Otto Helweg, Zohrab Samani, Jorge Garcia, Rao Govindaraju, Dinesh R. Katti, and Clinton Willson 3.1 General ............................................................................................ 83 3.2 Design of Borehole, Casing, and Screen ................................... 85 3.3 Design of Filter Pack .................................................................... 91 3.4 Design of Well Screen ................................................................... 101 3.5 Economic Considerations in Design .......................................... 105 3.6 Summary ........................................................................................ 120 3.7 References ....................................................................................... 120 4. CONSTRUCTION, DEVELOPMENT, AND TESTING OF WATER WELLS .............................................................................. 123 Dennis E. Williams 4.1 General ............................................................................................ 123 4.2 Site Assessment for Potential Municipal Water Well Sites ................................................................................................. 125 4.3 Drilling, Installation, and Cementing of Conductor Casing ............................................................................................. 133 4.4 Drilling the Borehole .................................................................... 134 4.5 Geophysical Borehole Logging ................................................... 164 4.6 Isolated Aquifer Zone Testing .................................................... 170 4.7 Water Quality and Yield .............................................................. 171 4.8 Well Destruction Methods ........................................................... 172 4.9 Mechanical Grading Analyses .................................................... 195 4.10 Lithologic Descriptions of Formation Materials Using Unifi ed Soil Classifi cation System ............................................. 196 4.11 Preparation for Well Completion ............................................... 196 4.12 Installation of Casing, Screen, and Filter Pack......................... 201 4.13 Interaquifer Seals .......................................................................... 205 4.14 Principles of Well Development ................................................. 205 4.15 Final Development with Deep Well Turbine Pump (Vertical Line Shaft) ...................................................................... 211 4.16 Pumping Tests ............................................................................... 213 4.17 Flowmeter (Spinner) Survey ....................................................... 229 4.18 Collecting Water Quality Samples at the End of the Constant-Rate Test ........................................................................ 230 4.19 Miscellaneous Final Tasks ........................................................... 230 4.20 Final Report including Analysis ................................................. 234 4.21 Acknowledgments ........................................................................ 235 4.22 References ....................................................................................... 235 CONTENTS vii 5. CORROSION OF WATER WELLS ................................................... 239 Robert G. McLaughlan 5.1 General ............................................................................................ 239 5.2 Theory of Corrosion ..................................................................... 239 5.3 Types of Corrosion ........................................................................ 242 5.4 Corrosive Properties of Water ..................................................... 246 5.5 Corrosion of Water-Well Systems ............................................... 248 5.6 Prediction of Corrosion ................................................................ 251 5.7 Evaluation of Corrosion Rate Data ............................................ 257 5.8 Protective Measures for Corrosion............................................. 259 5.9 Troubleshooting for Well Corrosion .......................................... 263 5.10 Solved Design Example 1 ............................................................ 264 5.11 References ....................................................................................... 282 6. INCRUSTATION OF WATER WELLS ............................................. 285 John H. Schneiders 6.1 General ............................................................................................ 285 6.2 Theory of Incrustation .................................................................. 285 6.3 Analysis of Groundwater ............................................................ 286 6.4 Forms of Incrustation ................................................................... 290 6.5 Causes of Incrustation .................................................................. 290 6.6 Effects of Velocity, Pressure, and Temperature Changes ........ 291 6.7 Chemical Incrustation .................................................................. 292 6.8 Physical Incrustation .................................................................... 293 6.9 Biological Incrustation ................................................................. 294 6.10 Character of Iron Deposits .......................................................... 297 6.11 Field Testing of Incrustation ....................................................... 298 6.12 Timely Maintenance ..................................................................... 299 6.13 Acid Treatment .............................................................................. 301 6.14 Chlorine Treatment ....................................................................... 305 6.15 Polyphosphate Treatment ............................................................ 308 6.16 Design Considerations to Prevent Well Fouling ...................... 309 6.17 References ....................................................................................... 312 6.18 Recommended Reading ............................................................... 312 7. WELLHEAD PROTECTION FOR WATER WELLS ...................... 315 Zohrab Samani and Jorge Garcia 7.1 General ............................................................................................ 315 7.2 Wellhead Protection and Wellhead Protection Area ............... 316 7.3 Fundamentals of Groundwater Flow and Contaminant Transport ........................................................................................ 318 7.4 Delineation Methods for the Wellhead Protection Area ........ 322 7.5 A Case Study ................................................................................. 329 7.6 Summary ........................................................................................ 335 7.7 References ....................................................................................... 336 viii CONTENTS 8. MAINTENANCE OF WATER WELLS ............................................. 337 Stuart A. Smith 8.1 General ............................................................................................ 337 8.2 Causes of Well Performance: Problems and Failures ............. 337 8.3 Preventive Material, Design, and Treatment Choices to Avoid Well Performance Decline and Failure ..................... 340 8.4 Preventive Maintenance, Monitoring Methods, and Records ........................................................................................... 351 8.5 Schedule of Well Maintenance Activities .................................. 356 8.6 Economics of Well Maintenance ................................................. 356 8.7 The Future: Field and Laboratory Research on Well Maintenance ................................................................................... 360 8.8 Solved Design Example 1 ............................................................ 360 8.9 Solved Design Example 2 ............................................................ 367 8.10 References ....................................................................................... 370 APPENDIX A. EXAMPLE OF A WATER-WELL SYSTEM DESIGN .................................................................................................. 373 Dennis E. Williams A.1 General .......................................................................................... 373 A.2 Hydrogeology ............................................................................... 375 A.3 Groundwater ................................................................................ 377 A.4 Well Site Characteristics .............................................................. 380 A.5 Technical Aspects of Water Wells .............................................. 383 A.6 Geophysical Logging and Aquifer Zone Testing.................... 384 A.7 Design Aspects of Water Wells .................................................. 387 A.8 Pumping Tests .............................................................................. 392 A.9 Video Survey, Plumbness, and Alignment .............................. 399 A.10 Well Equipping, Operation, and Maintenance ....................... 399 A.11 Acknowledgments ....................................................................... 401 APPENDIX B. TECHNICAL SPECIFICATIONS FOR DRILLING, CONSTRUCTING, AND TESTING OF WATER WELLS .............................................................................. 405 Dennis E. Williams B.1 General .......................................................................................... 405 B.2 Drilling Method and Equipment .............................................. 417 B.3 Well Construction Sequence ...................................................... 423 B.4 Testing For Yield and Drawdown ............................................. 441 B.5 Video Survey ................................................................................ 445 B.6 Well Disinfection .......................................................................... 445 B.7 Figures ........................................................................................... 447 B.8 Attachments .................................................................................. 448 APPENDIX C. GLOSSARY ..................................................................... 455 CONTENTS ix APPENDIX D. NOTATION .................................................................... 471 APPENDIX E. SI UNIT PREFIXES ....................................................... 483 APPENDIX F. CONVERSION TABLE AND USEFUL CONSTANTS ......................................................................................... 485 INDEX .......................................................................................................... 491