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1 OS-299 (11-13) TRANSMITTAL LETTER PUBLICATION: Publication 293 DATE: 12/18/20 SUBJECT: December 2020 Edition, Publication 293 - Geotechnical Engineering Manual INFORMATION AND SPECIAL INSTRUCTIONS: Publication 293 (Geotechnical Engineering Manual), December 2020 Edition is to be issued with this letter. Clarification was added to Chapter 8 of this publication regarding rock scaling. Chapter 2 updates were completed for any broken links. Also, included throughout, are updates or revisions that have been implemented via Strike-Off Letter or are editorial in nature. Chapter 9, Compaction of Embankment and Fills, and Chapter 10, Acid Producing Rock, of this manual were completed by subject matter experts and circulated for review and comments through the Clearance Transmittal process on CT# C-18-033 and CT# C-18-036, respectively.

2 This release incorporates Chapter 9 and 10 into this edition of Publication 293. Appendix C, Limited Mobility Grouting Use Guidelines, of this manual was completed by subject matter experts and circulated for review and comments through the Clearance Transmittal process on CT# H-20-002. This release incorporates Appendix C into this edition of Publication 293. CANCEL AND DESTROY THE FOLLOWING: Publication 293, April 2018 Edition ADDITIONAL COPIES ARE AVAILABLE FROM: PennDOT SALES STORE (717) 787-6746 phone (717) 525-5180 fax PennDOT website - Click on Forms, Publications & Maps DGS warehouse (PennDOT employees ONLY) APPROVED FOR ISSUANCE BY: Christine Reilly, , Chief Bureau of Project Delivery Construction and Materials Division By: Beverly Miller, , Chief Geotechnical Engineer Construction and Materials Division PUB 293 (12-20) Publication 293 2020 Edition [THIS PAGE IS INTENTIONALLY LEFT BLANK] i PENNSYLVANIA DEPARTMENT OF TRANSPORTATION PUBLICATION 293 2020 GEOTECHNICAL ENGINEERING MANUAL TABLE OF CONTENTS BACKGROUND.

3 Vi CHAPTER 1 GEOTECHNICAL WORK PROCESS, TASKS AND REPORTS INTRODUCTION .. 1-1 GEOTECHNICAL ENGINEERING ALTERNATIVES ANALYSIS PHASE .. 1-10 GEOTECHNICAL ENGINEERING PRELIMINARY DESIGN PHASE .. 1-20 GEOTECHNICAL ENGINEERING FINAL DESIGN .. 1-31 GEOTECHNICAL ENGINEERING SUBMISSIONS .. 1-37 GEOTECHNICAL INVOLVEMENT DURING CONSTRUCTION .. 1-68 CHAPTER 2 RECONNAISSANCE IN GEOTECHNICAL ENGINEERING INTRODUCTION .. 2-1 OFFICE RECONNAISSANCE .. 2-3 FIELD RECONNAISSANCE .. 2-13 CHAPTER 3 SUBSURFACE EXPLORATION INTRODUCTION .. 3-1 TEST BORINGS .. 3-3 TEST PITS .. 3-14 EXAMPLE 3-15 CONSIDERATIONS WHEN PLANNING SUBSURFACE EXPLORATION PROGRAM .. 3-16 TEST BORING EQUIPMENT, TOOLS AND, PROCEDURES .. 3-20 TEST BORING PROCEDURES/CONSIDERATIONS.

4 3-36 CHAPTER 4 LABORATORY TESTING INTRODUCTION .. 4-1 DEVELOPMENT OF A LABORATORY PROGRAM .. 4-4 GUIDELINES FOR SELECTING LABORATORY TESTS AND SOIL AND ROCK 4-5 PUB. 293, Table of Contents December 2020 ii DISTURBED, UNDISTURBED, AND REMOLDED SOILS SAMPLES .. 4-8 LABORATORY TESTING PRECAUTIONS .. 4-10 VERIFICATION OF LABORATORY TEST RESULTS .. 4-12 PRESENTATION OF LABORATORY TEST RESULTS .. 4-15 GEOTECHNICAL SOIL, ROCK, AND WATER LABORATORY TESTS .. 4-18 GEOTECHNICAL TEST CONSIDERATIONS .. 4-45 CHAPTER 5 SOIL AND ROCK PARAMETER SELECTION INTRODUCTION .. 5-1 UNDERSTANDING SOIL AND ROCK CONDITIONS .. 5-4 STANDARD PENETRATION TEST (SPT) AND N-VALUE .. 5-8 ROCK CORE DRILLING .. 5-11 ESTIMATING ENGINEERING PROPERTIES OF SOIL AND ROCK.

5 5-11 FINAL SELECTION OF DESIGN VALUES .. 5-39 CHAPTER 6 SOIL SLOPE STABILITY CHAPTER 7 SETTLEMENT CHAPTER 8 ROCK CUT SLOPE AND CATCHMENT DESIGN INTRODUCTION .. 8-1 ROCK CUT SLOPE TERMS AND DEFINITIONS .. 8-4 DESIGN SCOPE OF WORK .. 8-11 GEOTECHNICAL/GEOLOGICAL INVESTIGATIONS .. 8-13 ROCK CUT SLOPE DESIGN FOR STABILITY .. 8-17 ROCK SLOPE BENCHES .. 8-24 ROCKFALL CATCHMENT DESIGN .. 8-29 ROCKFALL SIMULATION MODELING .. 8-32 HAZARD MITIGATION SYSTEMS .. 8-37 SPECIAL GEOTECHNICAL CONSIDERATIONS .. 8-42 ROCKFALL REMOVAL CONSIDERATIONS .. 8-43 CONTRACTOR SPECIFICATION CONSIDERATIONS .. 8-43 CHAPTER 9 COMPACTION OF EMBANKMENTS AND FILLS INTRODUCTION .. 9-1 MECHANICS OF COMPACTION .. 9-3 COMPACTION EQUIPMENT .. 9-7 LABORATORY AND FIELD TESTING FOR COMPACTION.

6 9-8 PUB. 293, Table of Contents December 2020 iii FIELD OPERATIONS .. 9-13 CHAPTER 10 ACID-PRODUCING ROCK INTRODUCTION .. 10-1 UNDERSTANDING ACID-PRODUCING ROCK (APR) .. 10-1 APR PLANNING AND MANAGEMENT .. 10-6 PRELIMINARY APR ASSESSMENT .. 10-7 DETAILED APR INVESTIGATION .. 10-9 SAMPLE TESTING TO DETERMINE THE POTENTIAL FOR APR .. 10-18 ANALYSIS AND INTERPRETATION OF TEST RESULTS .. 10-21 ACID DRAINAGE MITIGATION 10-23 ACID-PRODUCING ROCK AND SOIL MITIGATION METHODS .. 10-26 EXPANSIVE DEPOSITS PYRITIC SHALES AND SULFATE SOILS .. 10-44 OTHER DESIGN CONSIDERATIONS .. 10-47 CONSTRUCTION .. 10-48 POST-CONSTRUCTION MONITORING .. 10-49 CHAPTER 11 GEOSYNTHETIC REINFORCED SOIL (GRS) SLOPES INTRODUCTION .. 11-1 REINFORCED SLOPE DESIGN REQUIREMENTS.

7 11-1 GRS SLOPES IN FLOODPLAINS AND SUBSURFACE DRAINAGE .. 11-2 GRS STABILITY AND FOUNDATION SUPPORT .. 11-3 SLOPE FACE TYPE .. 11-4 GEOMETRIC, LOAD, AND PERFORMANCE REQUIREMENTS FOR DESIGN .. 11-5 EARTH MATERIAL REQUIREMENTS .. 11-8 GEOSYNTHETIC REQUIREMENTS .. 11-11 CONSTRUCTION RELATED CONSIDERATIONS .. 11-15 DESIGN SUBMISSION .. 11-16 CHAPTER 12 GEOCELL INTRODUCTION .. 12-1 GEOCELL SELECTION GUIDELINES .. 12-3 CHAPTER 13 GEOFOAM INTRODUCTION .. 13-1 OVERVIEW OF GEOFOAM MANUFACTURING PROCESS .. 13-1 EXPANDED POLYSTYRENE (EPS) GEOFOAM PROPERTIES .. 13-2 PUB. 293, Table of Contents December 2020 iv TYPICAL USES OF EPS GEOFOAM .. 13-3 ECONOMIC ANALYSES OF EPS 13-4 DESIGN REQUIREMENTS AND CONSIDERATIONS .. 13-6 CONSTRUCTION REQUIREMENTS AND CONSIDERATIONS.

8 13-19 CALCULATIONS FOR THE DETERMINATION OF REQUIRED EPS GEOFOAM COMPRESSIVE RESISTANCE AND DENSITY .. 13-29 CHAPTER 14 GEOSYNTHETICS USE GUIDELINES CHAPTER 15 ROCK SLAKE DURABILITY INTRODUCTION .. 15-1 CONDITIONS WHERE SLAKING MAY AFFECT FOUNDATION DESIGN . 15-3 IDENTIFYING SLAKING ROCK .. 15-5 SLAKE TESTING METHODS, RESULTS AND INTERPRETATION .. 15-11 FOUNDATION DESIGN GUIDELINES FOR SLAKING ROCK .. 15-17 APPENDIX A INSTRUMENTATION FIELD (IN-SITU) TESTING APPENDIX B CLAY AND IMPERVIOUS LINERS APPENDIX C LIMITED MOBILITY GROUTING USE GUIDELINES INTRODUCTION ..C-1 LIMITED MOBILITY GROUTING APPLICATIONS ..C-4 SUBSURFACE EXPLORATIONS FOR GROUTING ..C-4 LIMITED MOBILITY GROUTING PROGRAM DESIGN ..C-8 CONSTRUCTION ..C-18 DATA APPENDIX D ROCK MASS RATING (RMR) APPENDIX E DESIGN/CONSTRUCTION IN KARST APPENDIX F GROUND MODIFICATION APPENDIX G SUBSIDENCE v [THIS PAGE IS INTENTIONALLY LEFT BLANK] vi PENNSYLVANIA DEPARTMENT OF TRANSPORTATION PUBLICATION 293 2020 GEOTECHNICAL ENGINEERING MANUAL BACKGROUND Publication 293, Geotechnical Engineering Manual provides policy and guidance for geotechnical engineering activities for roadway and structure projects for the Pennsylvania Department of Transportation.

9 This publication addresses geotechnical engineering activities required for three phases of projects, including: alignment alternatives analyses, preliminary design, and final design. Publication 293 is applicable to both design/bid/build projects and design/build projects and applies to design done by consultants and design done in-house by the Department. The geotechnical engineering work for structures must also follow the requirements specified in Publication 15 (Design Manual Part 4 (DM-4), Part A, Chapter 1, Sections and ), and Publication 448 (Innovative Bidding Toolkit, Chapter 3, Section ). Additionally, Publication 293 provides policy and guidance on completing structure foundation tasks and describes how to integrate geotechnical work for structures and roadway in the most efficient and coherent manner.

10 Since each project is unique and requires engineering judgment based on the specific project circumstances, this publication should not be used as the geotechnical scope of work for projects. Instead, the scope of work for each project should be based on project specific information and goals, using this publication only as a reference. Additionally, since roadway and structure projects involve numerous people from within the Department, outside agencies, and consultants, communication is critical from the onset of the project through construction to produce a successful project. This includes early (during project scoping) and continual involvement of geotechnical personnel. The policies set forth in this publication are to be considered minimum requirements.