, -?>r:~-'-"'; y!tfLPftttC£ IA .. 76~?:J REPORT ~R&U\J\11\, LIBRARY COpy ENVIRONMENTAL EFFECTS OF SLAKING OF SURFACE MINE SPOILS EASTERN & CENTRAL UNITED STATES prepared for: UNITED STATES DEPARTMENT OF THE INTERIOR BUREAU OF MINES by: D'Appolonia Consulting Engineers, Inc. 10 Duff Road Pittsburgh, Pennsylvania 15235 Final Report Contract No. J0285024 SEPTEMBER 1980 2 3. Recipi~nt's Acc~ssion No. REPORT DOCUMENTATIONll. R~pon No. 1 . PAGE 4. Titl~ and Subtitl~ 5. R~pon Dat~ September, 1980 Environmental Effects of Slaking of Surface Mine Spoils - Eastern and Central United States 6. 7. Author(s) 8. Performin~ Organization Rept. D. E. Andrews, J. L. Withiam, E. F. Perry, and H. L. Crouse No. 78- 75 9. Performing Organization Name and Address 10. Project/Task/ll'ork Unit No. D'Appolonia Consulting Engineers, Inc. 10 Duff Road 11. Contract/Grant No. Pittsburgh, PA 15235 J0285024 12. Sponsoring Organization Name and Addr~ss 13. Type of Report & Period United States Department of the Interior Covered Final Report Bureau of Mines 10/78 - 9/80 Denver Federal Center 14. Denver, CO 80225 15. Supplementary Notes 16. Abstracts The objective of this study was to investigate the environmental effects of slaking of sur face mine spoils. To accomplish this, both field and laboratory programs were undertaken,. supplemented by a thorough literature search. The field program consist- ed of drilling the highwall as well as test pitting 1n recent, two-, five- , and ten- year-old spoil piles at four active mining sites 1U the eastern bituminous coal fields. Pertinent observations were made and samples collected for laboratory analyses which consisted of several standard geotechnical, agronomic, and geochemic al tests. Durao'i- lity tests utilized inc luded jar slake, cyc lic wet-dry, rate of slake, and slake durability tests. Correlation between field and laboratory portions was made and re- sults presented. The report is conc luded with a discussion of the slaking process and associated environmental impacts, proposal of a preliminary classification system for use in premine planning, and presentation of management techniques to optimize the slaking process. 17. Document Analysis •. Descriptors Environmental Effects, Slaking, Eastern and Central United States, Slaking Mechanisms, Classification, Management Techniques, Annotated Bibliography b. Identifiers/Open-Ended Terms Surface Coal Mine Spoils, Field Investigations, Laboratory Testing c. COSA TI Field/Group 8D, 8G, 81 18. Availability Stat~m~nt 19. Security Class (This 21. No. of Pages Report ) 'UNCLASSIFIED 247 Release Unlimited 20. Security Class {This 22. Pric~ P.~ NCLASSIFIED FORM NTIS.3S '~EV. 10-131 ENDORSED BY ANSI AND UNESCO. THIS FORM MAYBE REP RODUCED USCOMM·OC 12es·P l. FOREWORD This report was prepared by D'Appolonia Consulting Engineers, Inc., under USBM Contract No. J0285024. The contract was initiated under the Mining Environmental Research Program and completed under the Minerals Environmental Technology Program. It was administered under the technical direction of Bureau of Mines with Mr. Michael J. Bailey acting as Technical Project Officer. Mr. William R. Case was the Con­ tract Administrator for the Bureau of Mines. This report is a summary of the work recently completed as a part of this contract during the period October 1978 to November 1979. This report was submitted by the authors on September 30, 1980. We wish to acknowledge the participation of the many D'Appolonia employ­ ees who aided with the various phases and tasks of the study. Special recognition is given to Mr. Kevin Roberts who provided the majority of literature review during the initial stages of the project. We extend our grateful appreciation to Mr. William Strohm, Waterways Experimental Station, Vicksburg, Mississippi for the loan of the slake durability testing apparatus and to the mining companies and mine per­ sonnel for their cooperation during the investigations. Their assis­ tance and friendly attitudes were key factors to a successful completion of this project. 2 TABLE OF CONTENTS PAGE LIST OF TABLES 6 LIST OF FIGURES 7 1.0 INTRODUCTION AND SUMMARY 10 2.0 SLAKING MECHANISMS 12 2.1 CONFINING STRESS RELIEF 13 2.2 HYDRATION FORCE INCREASE 17 2.3 DOUBLE LAYER REPULSION FORCE INCREASE 19 2.4 PORE AIR COMPRESSION 20 2.5 NEGATIVE PORE PRESSURE INCREASE 22 2.6 CRYSTAL GROWTH FORCE INCREASE 23 2.7 BOND OR PARTICLE DETERIORATION 25 2.8 SURFACE ENERGY REDUCTION 26 3.0 GEOLOGY OF COAL-BEARING UNITS OF APPALACHIAN AND ILLINOIS BASINS 28 3.1 GEOLOGY OF THE APPALACHIAN AND ILLINOIS BASINS 29 3.1.1 Appalachian Basin 31 3.1.2 Illinois Basin 32 4.0 MINING AND RECLAMATION TECHNIQUES 45 4.1 EXCAVATION AND PLACEMENT TECHNIQUES 45 4.2 RECLAMATION TECHNIQUES 47 5.0 FIELD PROGRAM 49 5.1 PRELIMINARY SITE SELECTION 49 5.2 SITE RECONNAISSANCE AND FINAL SELECTION 50 5.3 HIGHWALL EXPLORATION 50 5.4 MINE SPOIL EXPLORATION 52 5.5 INTERVIEWS WITH MINE AND REGULATORY PERSONNEL 56 6.0 SITE CONDITIONS 59 6.1 SITEA 59 6. I. I Geologic Condit ions 60 6.1.2 Mining Technology and Spoil Handling 60 6.1.3 Reclamation Techniques 63 6.2 SITE B 64 6.2.1 Geologic Conditions 64 6.2.2 Mining Technology and Spoil Handling 64 6.2.3 Reclamation Techniques 67 6.3 SITE C 68 6.3.1 Geologic Conditions 68 6.3.2 Mining Technology and Spoil Handling 69 6.3.3 Reclamation Techniques 69 3 TABLE OF CONTENTS (Continued) PAGE 6.4 SITE D 72 6.4. I Geologic Conditions 72 6.4.2 Mining Technology and Spoil Handling 73 6.4.3 Reclamation Techniques 76 7.0 PREVIOUSLY DEVELOPED SLAKING-RELATED CLASSIFICATIONS AND LABORATORY TECHNIQUES 78 7. I CLASSIFICATION 78 7. I.I Taxonomic Classification Systems 78 7.1.2 Engineering (Technical) Classification Systems 79 7.2 MATERIAL TESTING 88 7.2.1 Identification Tests 90 7.2.2 Durability Tests 93 7.2.3 Strength Tests 97 8.0 LABORATORY PROGRAM 100 8.1 SAMPLE SELECTION AND PREPARATION 102 8.2 DURABILITY TESTS 103 8.3 IDENTIFICATION TESTS 103 8.4 ANCILLARY TESTS 105 9.0 RESULTS OF FIELD AND LABORATORY PROGRAMS 109 9.1 FIELD PROGRAM RESULTS 109 9.1.1 Modes of Slaking 109 9.1.2 Impact of Material Properties on Slaking 110 9.1.3 Impact of Mining Techniques on Slaking 110 9.1.4 Physical Characteristics of Spoil Piles as Related to Slaking 113 9.1.5 Environmental Effects of Slaking 130 9.2 LABORATORY TESTING PROGRAM 132 9.2.1 Durability Tests 133 9.2.1.1 Jar Slake Test 135 9.2.1.2 Cyclic Wet/Dry Test 136 9.2.1.3 Cyclic Rate of Slaking Tests 140 9.2.1.4 Slake Durability Test 143 9.2.1.5 Summary of Durability Test Results 146 9.2.2 Identification Tests 149 9.2.2.1 Moisture Content 150 9.2.2.2 Grain Size (Disaggregated) and Atterberg Limits 154 9.2.2.3 Unit Weight 154 9.2.2.4 I: I (Soil) pH 154 9.2.2.5 Exchange/Adsorption Capacity 157 9.2.2.6 Petrographic (Thin Section) Examination 161 9.2.2.7 X-Ray Diffraction 162 4 TABLE OF CONTENTS (Continued) PAGE 9.2.3 Ancillary Tests 162 9.2.3.1 Point Load Tests 162 9.2.3.2 Slake Fluid pH 166 9.2.3.3 Specific Conductance 166 9.2.3.4 Postdurability Testing 168 9.3 COMBINED FIELD AND LABORATORY RESULTS 168 9.3.1 Durability and Slaking Modes 169 10.0 CONCLUSIONS AND RECOMMENDATIONS 178 10.1 SUMMARY OF THE SLAKING PHENOMENON 178 10.2 ENVIROt~NTAL EFFECTS OF SLAKING 181 10.2.1 Hydrological Impacts 182 10.2.2 Slope Instability and Settlement 182 10.2.3 Erosion and Sedimentation 184 10.2.4 Vegetation Relationships 186 10.3 PROPOSED CLASSIFICATION SYSTEM 188 10.4 MANAGEMENT TECHNOLOGY 193 ANNOTATED BIBLIOGRAPHY 199 APPENDIX A - TEST PROCEDURES 233 5 LIST OF TABLES TABLE NO. TITLE PAGE 2. 1 Summary of Slaking Mechanisms: Material Relationships 14 2.2 Summary of Slaking Mechanisms: Environmental and Rate Relat ionships 16 3. 1 Summary of Coal-Bearing Units in Alabama-Cahaba Field 33 3.2 Summary of Coal-Bearing Units in Alabama-Coosa Field 34 3.3 Summary of Coal-Bearing Units in Alabama-Plateau Field 35 3.4 Summary of Coal-Bearing Units in Alabama-Warrior Field 36 3.5 Summary of Coal-Bearing Units in Eastern Kentucky 37 3.6 Summary of Coal-Bearing Units in Ohio 38 3.7 Summary of Coal-Bearing Units in Western Pennsylvania 39 3.8 Summary of Coal-Bearing Units in West Virginia 40 3.9 Summary of Coal-Bearing Units in Illinois 42 3.10 Summary of Coal-Bearing Units in Indiana 43 3.11 Summary of Coal-Bearing Units in Western Kentucky 44 5. 1 Outline of Descriptors Used for Mine Spoil Characterization 54 6.1 Site A: Summary of Lithologic Propert ies 61 6.2 Site B: Summary of Lithologic Propert ies 65 6.3 Site C: Summary of Lithologic Propert ies 70 6.4 Site D: Summary of Lithologic Properties 74 7. 1 Summary of Laboratory Tests Associated with Slaking 89 8. 1 Schedule for Identification Tests 106 9.1 Relationship of Slaking Modes to Rock Properties III 9.2 Summary of Durability Test Results 134 9.3 Summary of Slake Durability Test Results 144 9.4 Summary of Degradation Indices (DI) for Comparable Test Conditions 147 9.5 Summary of Unit Weight and 1:1 pH Determinations 156 9.6 Summary of Exchange/Adsorption Capacity Test Results 160 9.7 Summary of X-Ray Diffraction Analyses 163 9.8 Summary of Point Load Test Results 164 6 LIST OF FIGURES FIGURE NO.