Table of Contents. List of Figures...iii List of Tables... v Acknowledgments...vi Preface...vii Introduction... 1 Scope of Report...

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1 Table of Contents List of Figures...iii List of Tables... v Acknowledgments...vi Preface...vii Introduction... 1 Scope of Report Physicochemical Processes and Consequences for Geotechnical Systems Chemical reactions and attendant biological and physical processes Sulfide minerals Sulfate minerals Physical, chemical, and biological weathering Physical processes Chemical processes Biological processes Consequences for geotechnical projects and systems Heave and uplift pressures Concrete expansion / degradation Steel corrosion Acid production Strength and stability effects Case Histories Sulfide-induced heave study Microbially-induced sulfidic heave study Embankment fill study Subgrade study Stability study Acid drainage study Guidelines for Anticipating Problems Problematic formations and associated identifying clues Shale formations created in a marine or estuarine environment Visual indications of shales created in a marine or estuarine environment Fine-grained rock and soil with significant pyrite content Visual indications of pyritic fine-grained rock and soil Rocks with recognized potential for acid production from sulfide minerals Visual indications of sulfidic rocks with recognized acid potential Rock formations with recognized potential for heave from sulfide minerals Visual indications of sulfidic rocks with recognized heave potential Guidelines for Practitioners Recommended procedures for site evaluation Review of regional and site-specific geologic information Early reconnaissance of the site Grab samples and drilled core samples for testing Geophysical testing... 60

2 ii Chemical testing Total sulfur test Sulfur fractionation test Sulfide sulfur field method Acid-Base Accounting (ABA) test Hydrogen peroxide oxidation test Soluble sulfate test Magnitudes, rates, and parameters governing the effects of pyrite oxidation Expected rates and magnitudes of swell pressures resulting from pyritic expansion Time-rate of pyrite oxidation Mitigation options for geotechnical systems Conclusion Possible Related Research Paths References Appendices A. Mitigation Options...A-1 B. Survey of Practitioners... B-1 C. Chemical Test Procedures... C-1 D. Glossary...D-1 E. Visual Identification of Sulfidic Geomaterials... E-1

3 iii List of Figures Figure 1 - Schematic of (a) sulfide-induced and (b) sulfate-induced heave... 5 Figure 2 - Plot of sulfide sulfur content vs. amount of heave... 6 Figure 3 - Pyrite octahedral crystals in organic marine shale... 8 Figure 4 - Cubical fool s gold form of pyrite... 8 Figure 5 - Pyrite framboids... 8 Figure 6 - Anhedral pyrrhotite grains... 9 Figure 7 - Effects of pyrite oxidation in New Albany Shale Figure 8 - Fibrous gypsum crystal Figure 9 - Shale platelets forced apart by gypsum growth Figure 10 - Geologic cross-section showing origin and migration of gypsum in soil overlying pyritic bedrock Figure 11 - Comparison of rate constants (k) in relation to ph for Eqs. 1, 2, and Figure 12 - The chemical alteration of pyrite and calcite into gypsum Figure 13 - Ferrobacillus-Thiobacillus bacteria isolated from weathered shale below a heaved floor Figure 14 - Sulfide-induced heave of library floor and bookshelves at Johnson City Public Library, Johnson City, Tennessee Figure 15 - Aerial photo of nine Questa mine waste rock piles, which span 677 acres, in Questa, New Mexico Figure 16 - One of the mine waste rock piles at the Questa molybdenum mine, Questa, New Mexico Figure 17 - Schematic diagram defining the conditions needed for the formation of metalliferous black shales Figure 18 - Locations of typically pyritic Devonian Shales in North America Figure 19 - Geologic time scale Figure 20 - Marine fossil found in Millboro Shale formation (Devonian age) Figure 21 - Devonian spiriferid ( winged brachiopod) Figure 22 - Stringocephalus brachiopod commonly used to identify Middle Devonian strata... 42

4 iv Figure 23 - SEM photographs of Marcellus Shale formation, Devonian age Figure 24 - Fool s gold pyrite crystals Figure 25 - Set of color chips from Munsell Color Chart Figure 26 - Munsell hue designations Figure 27 - Munsell Rock Color Chart Figure 28 - Corrosion of corrugated steel buried culvert from pyrite oxidation Figure 29 - Concrete degradation resulting from sulfate attack and corrosion Figure 30 - Floor heave resulting from pyrite oxidation Figure 31 - Vertical displacement of floor from pyrite oxidation Figure 32 - Floor heave requires leveling of generators Figure 33 - Results of simulated weathering of Alum shales Figure 34 - Schematic diagrams of oxidation/dissolution zones and fluxes of oxygen and water transporting sulfuric acid Figure E.1 - Reference Chart of Munsell Colors Associated with Sulfidic and Other Types of Geomaterials... E-1 Figure E.2 - Flake of pyrite in Millboro Shale... E-2 Figure E.3 - Cubical crystalline pyrite, fool s gold... E-2 Figure E.4 - Fibrous gypsum crystal... E-2 Figure E.5 - Marine fossil in Millboro Shale... E-2 Figure E.6 - Effects of pyrite oxidation on New Albany Shale... E-2 Figure E.7 Outcrop of pyritic, calcareous Sevier Shale at the site of the Johnson City Public Library (TN)... E-2 Figure E.8 - Visible evidence of weathering by pyrite oxidation of exposed face of Millboro Shale... E-2

5 v List of Tables Table 1 - Volume Increases of the Crystalline Solid Phases of Selected Mineral Transformations Table 2 - Pyrite Oxidation Effects on Various Geotechnical Projects and Systems Table 3 - Published Guidelines for Handling Pyritic Materials Table 4 - Simplified Weathering Classification System Relating Geological Description and Engineering Significance Table 5 - Examples of Pyritic Shales Created in a Marine or Estuarine Environment Table 6 - Examples of Fine-Grained Rock and Soil Types with Significant Pyrite Content Table 7 Munsell Color Guidelines for Pyritic Geomaterials Table 8 - Examples of Rocks with Recognized Potential for Acid Production from Sulfide Minerals Table 9 - Examples of Rock Formations with Recognized Potential for Heave from Sulfide Minerals Table 10 - Iron and Sulfate Alterations in Shale Samples Over Time Table 11 - Heave Parameters Resulting from Pyrite Oxidation Table 12 - IPPG Rating Classification Table A - Mitigation Options and Affected Systems...A-1 Table B - Responses to Survey of Practitioners... B-4