ENGINEERING GEOLOGY FIELD MANUAL SECOND EDITION VOLUME I 1998 REPRINTED 2001 U.S. Department of the Interior Bureau of Reclamation The Mission of the Department of the Interior is to protect and provide access to our Nation's natural and cultural heritage and honor our trust ·responsibilities to tribes. · The Mission ofthe Bureau of Reclamation is to manage, develop, and protect water and related resources in an environmentally and economically sound manner in the interest of the American public. Information contained in this manual regarding commercial products or firms may not be used for advertising or promotional purposes and is not an endorsement of any product or firm by the Bureau of Reclamation. The information contained in this manual was developed for the Bureau of Reclamation; no wtuT8Ilty as to the accuracy, usefulness, or completeness is expressed or imolied. 11 Aclm.owledgmenu tor Second Edition The original compilation and p~paration of this manual involved many engineering geologists and geophysicists within Reclamation. Their input is greatly appreciated. This second edition incorporates comments on the first edition and technological changes since the first edition was prepared appro:limately 10 years ago. Without the comments and i.JJ.put from the Denver, Regional, and Area Offices the revision would not have happened. Special thanks to Sam Bartlett, Engineering Geology Group 1 Manager, for his support and input throughout the preparation of the manual. Although there are too many people to acknowledge individually who contributed to the revisions and the second edition, Frank Calcagno, Mel Hill (retired), Sandy Kunzer, Jeff Farrar, SharoJ;l Hebenstreit, Linda Arrowwood, and Peter Rohrer made especially significant contributions. Mark McKeown contributed to and edited the second edition. Continued recognition ili given to Jerry S. Dodd (retired), who initiated the manual; Jeny's successor, Newcomb Bennett (retired), who kept the manual moving; and to Steve D. Markwell (retired), who saw the first edition completed. We extend our thanks and appreciation to Louis R. Frei, who helped establish and document many geological standards of practice, and to Richard H. Throner, who wrote much of the original manual, who assembled and served on committees for preparation and review, to Sam R. Bartlett who compiled and printed the early loose leaf ven:~ion of the manual, and to Mel Hill who completed the publication of the first edition. To the ~gion-al Geologists and their staffs and the many geotechnical engineers who offered comments that have been mcorporated into the manual we extend our thanks and appreciation for their work as well. The manual would not be oeomplete with-out the drawings and figures; to the engineering and physical science technicians we extend our gratitude and thanks. lll FOREWORD TO THE SECOND EDITION Approximately 10 years have gone by since the first edition was published, and technolOgy and missions have changed significantly. This second edition incorporates many modifications and additions. The Global Positioning System (GPS) baa revolutionized how we survey and locate OU1'8elves in the field, computers are used extensively ta collect and evaluate data, and computer aided modeling, design, and drafting are almost universal. Reclamation has a greater emphasis on maintenance and safety of infrastnicture, dam safety analyses and modifications, and water resource management than on design and construction of new hydraulic structures. Techniques for these activities and environmental restoration/hazardous waste remediation activities are reflected ill' this edition. A few of the moat significant changes to the manual are the addition of a section on concrete core logging, a chapter on hazardous waste site investigations, and an index to facilitate finding relevant information. Many other suggested revisions and improvements collected since the manual was first published also are incorporated. The manum now is in two uolumes. Volume I contains material commonly needed in the field, and Volume II includes reference or other material. As in the first edition, the Engineering Geolcgy Fkld Manual presents the practices for the collection of geologic data obtained by the Burcnu of Reclamation. The manual establishes common guidelines, procedures, and concepts for the collection, evaluation, and presen­ tation of geologic i.¢onnation. The analyai.l! of geologic conditions, the preparation ofdesigns and specifications, and effective construction monitoring and use of geo­ logical information to assess site characteri.l!tics and ri.l!k, require consi.l!tent, comprehen8ive, and timely geologic v information. The use of these guidelines by all Recla­ mation engineering geologists collecting, documenting, evaluating, and presenting geological and geotechnical data promotes consistency, helps assure that the requind evaluations and data are complete, and promotes inte­ gration and coordination of geological and engineering activities. The Engineering Geology Field Manual, in conjunction with the Engineering Geology Office Manual, forms the basis for the mutually beneficial exchange of ideas by Reclamation geologists. Experienced geologists will find useful reminders and new procedures and special tech­ niques, while less experienced engineering geologists and those from other disciplines can use the manual to expand their familiarity with geology as practiced in the Bureau of Reclamation. Review and comments on the manual are encouraged, and if you have comments ·or suggested additions, please forward them to the Technical Service Center Engineering Geology Groups. Richard Throner Leadership Team Member Geotechnical Services vi CONTENTS Page Acknowledgments ...................... iii Foreword .............................. v Chapter 1 Introduction ................. 1 Chapter 2 Geologic Terminology and Classifications for Geologic Materials .......................... 3 Established References for Geological Terminology ........................ 3 Geologic Classification of Materials ....... 4 Engineering Classification of Geologic Materials .......................... 5 Application and Use of Standard Indexes, Terminology, and Descriptors .......... 9 Units of Measurements for Geologic Logs of Exploration, Drawings, and Reports .. 12 Bibliography .......................... 15 Chapter 3 Engineering Classification and Description of Soil ................. 17 General .............................. 17 Classifications of Soils .................. 21 Abbreviated Soil Classification Symbols ... 39 Description of the Physical Properties of Soil ............................. 40 Narrative Descriptions and Examples ..... 48 Use of Soil Classification as Secondary Identification Method for Materials Other Than Natural Soils ............. 51 Bibliography .......................... 56 Chapter 4 Classification of Rocks and Description of Physical Properties of Rock ................. 57 Introduction .......................... 57 Rock Classification .................... 57 FIELD MANUAL Chapter 4 Classification of Rocks and Description of Physical Properties of Rock (continued) Page Description of Rock .................... 59 Example Descriptions .................. 86 Bibliography .......................... 90 Chapter 5 Terminology and Descriptions for Discontinuities ................. 91 General .............................. 91 Indexes for Describing Fracturing ........ 94 Description of Fractures ................ 98 Descriptions of Shears and Shear Zones ... 114 Bibliography .......................... 126 Chapter 6 Geologic Mapping and Documentation .................... 129 Responsibilities of the Engineering Geologist ........................... 129 Development of a Study Plan ............ 130 Specific Mapping Requirements .......... 133 Global Positioning System .............. 135 Site Mapping ......................... 153 Dozer Trench Mapping ................. 157 Backhoe Trench Mapping ............... 161 Construction Geologic Mapping .......... 167 Large Excavation Mapping .............. 168 Steep Slope Mapping ................... 169 Canal and Pipeline Mapping ............ 170 Underground Geologic Mapping ......... 171 Underground Geologic Mapping Methods .. 185 Photogeologic Mapping ................. 196 Analysis of Aerial Photographs .......... 198 viii CONTENTS Chapter 6 Geologic Mapping and Documentation (continued) Page Photoanalysis for Reconnaissance Geologic Mapping .................... 199 Availability of Imagery ................. 200 References ........................... 202 Bibliography .......................... 203 Chapter 7 Discontinuity Surveys ........ 205 General .............................. 205 Bibliography .......................... 211 Chapter 8 Exploration Drilling Programs ......................... 213 Introduction .......................... 213 Preparation of Drilling Specifications and Format ......................... 223 Chapter 9 Groundwater Data Acquisition Methods ........................... 227 Introduction .......................... 227 Design and Installation of Observation Wells and Piezometers ............... 229 Methods Used to Measure Groundwater Levels ............................. 235 Methods and Techniques Used to Estimate Flows from Seeps, Springs, and Small Drainages .......................... 241 Computer-Based Monitoring Systems ..... 242 Definitions ........................... 245 References ........................... 246 Bibliography .......................... 247