Soil and Groundwater Remediation

CHUNLONG (CARL) ZHANG is a professor of environmental science at the College of Science and Engineering, University of Houston-Clear Lake, and a registered professional engineer (PE) in the field of environmental engineering. A noted expert in environmental remediation, he is also the author of the popular textbook Fundamentals of Environmental Sampling and Analysis published by Wiley.

About the Author xv

Preface xvii

Acknowledgments xxi

Whom This Book is Written For xxiii

To the Instructor xxv

List of Symbols xxvii

About the Companion Website xxxiii

1 Sources and Types of Soil and Groundwater Contamination 1

1.1 Uses of Surface Water vs. Groundwater 1

1.2 Groundwater Quantity vs. Groundwater Quality 4

1.3 Major Factors Affecting Groundwater Quality 6

1.4 Soil and Groundwater Contaminant Sources in the United States 8

1.4.1 Superfund Sites and Brownfields 9

1.4.2 RCRA Facilities and Underground Storage Tanks 12

1.4.3 DoD/DoE Sites 14

1.5 Contaminated Soil and Groundwater: A Global Perspective 14

1.6 Soil and Groundwater Remediation 16

1.6.1 Unique Challenges Relative to Air and Surface Water Pollution 16

1.6.2 Scope of Environmental Remediation 17

Bibliography 17

2 Subsurface Contaminant Fate and Transport 21

2.1 Frequent Soil and Groundwater Contaminants 22

2.1.1 Aliphatic and Aromatic Hydrocarbons 23

2.1.2 Halogenated Aliphatic Hydrocarbons 24

2.1.3 Halogenated Aromatic Hydrocarbons 25

2.1.4 Nitrogen‐containing Organic Compounds 26

2.1.5 Oxygenated Organic Compounds 27

2.1.6 Sulfur‐ and Phosphorus‐containing Organic Compounds 28

2.1.7 Inorganic Nonmetals, Metals, and Radionuclides 29

2.2 Abiotic and Biotic Chemical Fate Processes 30

2.2.1 Hydrolysis 31

2.2.2 Oxidation and Reduction 32

2.2.3 Biodegradation 35

2.3 Interphase Chemical Transport 35

2.3.1 Volatilization 36

2.3.2 Solubilization, Precipitation, and Dissolution 38

2.3.2.1 Solubility and Solubility Product for Inorganic Compounds 38

2.3.2.2 Solubility and Kow for Organic Compounds 41

2.3.3 Sorption and Desorption 42

2.4 Intraphase Chemical Movement 48

2.4.1 Advection 49

2.4.2 Dispersion and Diffusion 49

Bibliography 53

3 Soil and Groundwater Hydrology 59

3.1 Soil Composition and Properties 60

3.1.1 Constituents of Soils 60

3.1.2 Soil Physical and Chemical Properties 62

3.2 Basic Concepts of Aquifer and Wells 66

3.2.1 Vertical Distribution of Aquifer 66

3.2.2 Groundwater Well and Well Nomenclature 68

3.2.3 Hydrogeological Parameters 68

3.2.3.1 Specific Yield and Specific Retention 68

3.2.3.2 Hydraulic Conductivity and Permeability 70

3.2.3.3 Transmissivity and Storativity 71

3.3 Groundwater Movement 73

3.3.1 Flow in Saturated Zone 74

3.3.2 Flow in Unsaturated Zone 77

3.3.3 Flow to Wells in a Steady‐State Confined Aquifer 80

3.3.4 Flow to Wells in a Steady-State Unconfined Aquifer 82

3.3.5 Flow of Nonaqueous Phase Liquid 84

Bibliography 86

4 Legal, Economical, and Risk Assessment Considerations 91

4.1 Soil and Groundwater Protection Laws 92

4.1.1 Relevant Soil and Groundwater Laws in the United States 92

4.1.1.1 Safe Drinking Water Act 93

4.1.1.2 Resource Conservation and Recovery Act 94

4.1.1.3 Comprehensive Environmental Response, Compensation and Liability Act 95

4.1.1.4 Hazardous and Solid Waste Amendment 95

4.1.1.5 Superfund Amendment and Reauthorization Act 96

4.1.1.6 Small Business Liability Relief and Brownfields Revitalization Act 96

4.1.2 Framework of Environmental Laws in Other Countries 96

4.2 Cost Constraints in Remediation 97

4.2.1 Remediation Cost Elements 99

4.2.2 Basis for Remediation Cost Estimates 99

4.2.3 Cost Comparisons among Remediation Alternatives 101

4.3 Risk‐based Remediation 104

4.3.1 How Clean is Clean 104

4.3.2 Estimate Environmental Risk from Carcinogenic Compounds 108

4.3.3 Estimate Environmental Risk from Noncarcinogenic Compounds 112

4.3.4 Determine Risk-Based Cleanup Levels for Soil and Groundwater 113

4.3.4.1 Determining Maximum Concentration in Drinking Water and Air 114

4.3.4.2 Determining Allowable Soil Cleanup Level 115

4.3.4.3 Risk Involving Multimedia 116

Bibliography 118

5 Site Characterization for Soil and Groundwater Remediation 123

5.1 General Consideration of Site Characterization 124

5.1.1 Objectives and Scopes of Site Characterization 124

5.1.2 Basic Steps: Phase I, II, and III Assessment 125

5.1.2.1 Phase I Environmental Site Assessment 125

5.1.2.2 Phase II Environmental Site Assessment 126

5.2 Soil and Geologic Characterization 130

5.2.1 Stratigraphy, Lithology, and Structural Geology 130

5.2.2 Direct Drilling Methods 130

5.2.3 Drive Method Using Cone Penetrometer 132

5.2.4 Indirect Geophysical Methods 132

5.3 Hydrogeologic Site Investigation 138

5.3.1 Well Installation, Development, and Purging 138

5.3.2 Hydraulic Head and Flow Direction 139

5.3.2.1 Methods to Measure Hydraulic Head 140

5.3.2.2 Groundwater Flow Direction 140

5.3.3 Aquifer Tests to Estimate Hydraulic Conductivity 141

5.3.3.1 Slug Test: Hvorslev Method 142

5.3.3.2 Slug Test: Bouwer and Rice Method 143

5.3.3.3 Pumping Test: Theis Type‐Curve Method 143

5.4 Environmental Sampling and Analysis 146

5.4.1 Common Soil Samplers 146

5.4.2 Groundwater Sampling 148

5.4.2.1 Groundwater Sampling Tools 148

5.4.2.2 Cross‐Contamination in Groundwater Sampling 149

5.4.3 Vadose Zone Soil Gas and Water Sampling 150

5.4.4 Instruments for Chemical Analysis 150

Bibliography 152

6 Overview of Remediation Options 157

6.1 Types of Remediation Technologies 158

6.1.1 Classifications of Remediation Technologies 158

6.1.2 Common and Frequently Used Remediation Technologies 162

6.1.3 Technologies from Contaminant Perspectives 163

6.2 Development and Selection of Remediation Technologies 168

6.2.1 Remedial Investigation/Remedial Feasibility Study 172

6.2.2 Remediation Technologies Screening and Selection Criteria 174

6.2.3 Green and Sustainable Remediation 178

6.3 A Snapshot of Remediation Technologies 179

6.3.1 Description of Various Treatments 180

6.3.2 Treatment Train 180

Bibliography 183

7 Pump‐and‐Treat Systems 187

7.1 General Applications of Conventional Pump‐and‐Treat 188

7.1.1 Contaminant Removal versus Hydraulic Containment 188

7.1.2 Schemes of Injection/Extraction Well Placement 191

7.2 Design of Pump‐and‐Treat Systems 192

7.2.1 Capture Zone Analysis of Pump‐and‐Treat Optimization 194

7.2.2 Aboveground Treatment of Contaminated Groundwater 198

7.2.2.1 General Treatment Technologies Available 198

7.2.2.2 Design Considerations for Air Stripping 200

7.2.2.3 Design Considerations for Activated Carbon 202

7.3 Pump‐and‐Treat Limitations and Alterations 204

7.3.1 Residual Saturations of Nonaqueous Phase Liquid 204

7.3.1.1 Dissolved Contaminant from NAPLs 204

7.3.1.2 Residual Saturation 205

7.3.2 Tailing and Rebound Problems 209

7.3.2.1 Slow NAPL Dissolution 209

7.3.2.2 Slow Contaminant Desorption/Precipitate Dissolution 210

7.3.2.3 Slow Matrix Diffusion 211

7.3.2.4 Groundwater Velocity Variation 211

7.3.3 Alterations of Conventional Pump‐and‐Treat 212

7.3.3.1 Chemical Enhancement to Increase Contaminant Mobility and Solubility 213

7.3.3.2 Horizontal Wells, Inclined Wells, Interceptor Trenches, and Drains 213

7.3.3.3 Phased Extraction Wells, Adaptive Pumping, and Pulsed Pumping 215

7.3.3.4 Induced Fractures 216

7.3.3.5 Pumping in Conjunction with Permeable and Impermeable Barriers 217

Bibliography 219

8 Soil Vapor Extraction and Air Sparging 225

8.1 General Applications and Limitations of Vapor Extraction 226

8.1.1 Process Description and System Components 226

8.1.2 Chemical and Geologic Parameters Affecting Vapor Extraction 227

8.1.3 Pros and Cons of Vapor Extraction and Air Sparging 229

8.2 Soil Vapor Behavior and Gas Flow in Subsurface 231

8.2.1 Airflow Patterns in Subsurface 231

8.2.2 Vapor Equilibrium and Thermodynamics 233

8.2.3 Kinetics of Volatilization, Vapor Diffusion, and NAPL Dissolution 239

8.2.4 Darcy’s Law for Advective Vapor Flow 241

8.3 Design for Vapor Extraction and Air Sparging Systems 245

8.3.1 Quantitative Analysis for the Appropriateness of Soil Venting 245

8.3.2 Well Number, Flow Rate, and Well Location 249

8.3.3 Other Design Considerations 251

Bibliography 257

9 Bioremediation and Environmental Biotechnology 263

9.1 Principles of Bioremediation and Biotechnology 264

9.1.1 Microorganisms and Microbial Growth 265

9.1.1.1 Types of Microorganisms 265

9.1.1.2 Cell Growth on Contaminant 267

9.1.2 Reaction Stoichiometry and Kinetics 271

9.1.3 Biodegradation Potentials and Pathways 275

9.1.3.1 Biodegradation of Petroleum Aliphatic Hydrocarbons 276

9.1.3.2 Biodegradation of Single‐Ring Petroleum Aromatic Hydrocarbon (BTEX) 276

9.1.3.3 Biodegradation of Fuel Additives (MTBE) 278

9.1.3.4 Biodegradation of Polycyclic Aromatic Hydrocarbons (PAHs) 278

9.1.3.5 Biodegradation of Chlorinated Aliphatic Hydrocarbons (CAHs) 279

9.1.3.6 Biodegradation of Chlorinated Aromatic Compounds 280

9.1.3.7 Biodegradation of Explosive Compounds 280

9.1.4 Optimal Conditions for Bioremediation 281

9.1.4.1 Hydrogeologic Parameters 282

9.1.4.2 Soil/Groundwater Physicochemical Parameters 283

9.1.4.3 Microbial Presence 285

9.1.4.4 Contaminant Characteristics 285

9.2 Process Description of Bioremediation and Biotechnologies 286

9.2.1 In Situ Bioremediation 287

9.2.2 Ex Situ Biological Treatment 290

9.2.2.1 Biopiles and Composting 290

9.2.2.2 Landfarming 292

9.2.2.3 Bioslurry Reactors 293

9.2.3 Sanitary Landfills 293

9.2.4 Phytoremediation and Constructed Wetland 294

9.3 Design Considerations and Cost‐Effectiveness 300

9.3.1 General Design Rationales 300

9.3.1.1 Design for In Situ Groundwater Bioremediation 300

9.3.1.2 Design for Bioventing 301

9.3.1.3 Design for Biosparging 301

9.3.1.4 Design for Biopiles and Composting 301

9.3.1.5 Design of Landfill 302

9.3.2 Cost Effectiveness Case Studies 302

Bibliography 305

10 Thermal Remediation Technologies 315

10.1 Thermal Destruction by Incineration 316

10.1.1 Principles of Combustion and Incineration 316

10.1.1.1 Combustion Chemistry and Combustion Efficiency 316

10.1.1.2 Heating Values of Fuels/Wastes 319

10.1.1.3 Oxygen (Air) Requirement 320

10.1.1.4 Three T’s of the Combustion/Incineration 323

10.1.2 Components of Hazardous Waste Incinerator Systems 324

10.1.2.1 General Applications: Pros and Cons 324

10.1.2.2 Incinerator System Components 325

10.1.2.3 Four Types of Combustion Chambers 326

10.1.3 Design Considerations for Incineration 328

10.1.3.1 Incinerator Size and Dimensions 329

10.1.3.2 Factors Affecting Incinerator Performance 331

10.1.4 Regulatory and Siting Considerations 332

10.2 Thermally Enhanced Technologies 332

10.2.1 Temperature Effects on Physicochemical and Biological Properties 333

10.2.2 Heat Transfer Mechanisms in Soil and Groundwater 338

10.2.3 Required Heat‐Up Time and Radius of Influence 338

10.2.4 Use of Hot Air, Steam, Hot Water, and Electro‐Heating 339

10.2.4.1 Hot Air, Steam, Hot Water, and Electro-Heating 339

10.2.4.2 Flow Chart to Select Thermal Processes 343

10.3 Vitrification 344

Bibliography 347

11 Soil Washing and Flushing 353

11.1 Basic Principles of Soil Washing and Flushing 354

11.1.1 Overview of Soil Washing and Flushing 354

11.1.2 Surfactant‐Enhanced Contaminant Solubilization 356

11.1.3 Surfactant‐Enhanced Contaminant Mobilization 358

11.1.4 Cosolvent Effects on Solubility and Mobilization 361

11.2 Process Description, Technology Applicability, and Limitations 363

11.2.1 Ex Situ Soil Washing 364

11.2.2 In Situ Soil Flushing and Cosolvent Flooding 368

11.3 Design and Cost‐Effectiveness Considerations 370

11.3.1 Chemical Additives in Soil Washing and Flushing 370

11.3.2 Recycle of Chemical Additives and Disposal of Flushing Wastes 373

Bibliography 375

12 Permeable Reactive Barriers 379

12.1 Reaction Mechanisms and Hydraulics in Reactive Barriers 380

12.1.1 Barrier Technologies as a Viable Option for Pump‐and‐Treat 380

12.1.2 Dechlorination Mediated through Redox Reactions by Zero‐Valent Iron 381

12.1.3 Other Abiotic and Biotic Processes in Reactive Barriers 384

12.1.4 Hydraulics and Fouling Problems in Reactive Barriers 386

12.2 Process Description of Reactive Barriers 388

12.2.1 Configurations of Reactive Barriers 388

12.2.2 Available Reactive Media and Selection 389

12.2.2.1 Types of Reactive Media 389

12.2.2.2 Reactive Media Selection 391

12.3 Design and Construction Considerations 392

12.3.1 Barrier Design Concept 392

12.3.2 Construction Methods 394

Bibliography 400

13 Modeling of Groundwater Flow and Contaminant Transport 403

13.1 Governing Equations for Groundwater Flow 404

13.1.1 Saturated Groundwater Flow under Steady‐State Condition (Laplace Equation) 404

13.1.2 Saturated Groundwater Flow under Transient Condition 406

13.1.3 Unsaturated Groundwater Flow under Transient Condition (Richards Equation) 407

13.2 Governing Equations for Contaminant Transport 408

13.2.1 General Mass Balance Equations Considering Advection and Dispersion 408

13.2.2 Governing Equations for Contaminant Transport in Unsaturated Zone 411

13.2.3 Governing Equations Incorporating Adsorption and Reaction 412

13.2.4 General Concepts and Equations Describing Multiphase Flow and Transport 415

13.2.4.1 Processes Relevant to Multiphase and Multiple Components 415

13.2.4.2 Framework of Governing Equations for Multiphase Flow and Transport 417

13.3 Analytical Solutions to Flow and Transport Processes 420

13.3.1 Darcy’s Law: 1‐D Flow in Unconfined Aquifer (Dupuit Equation) 420

13.3.2 Fick’s Second Law: 1‐D Diffusion Only Solutions 422

13.3.3 Advection and Dispersion: 1‐D, 2‐D, and 3‐D Solutions to Slug Injection 424

13.3.4 Advection and Dispersion: 1‐D Solutions to Continuous Injection 425

13.3.5 Advection and Dispersion: 2‐D and 3‐D Solutions to Continuous Injection 427

13.4 Numerical Solutions to Flow and Transport Processes 430

13.4.1 Partial Differential Equations and Numerical Methods 430

13.4.2 2‐D Laplace Equation Using Finite Difference Method 433

Bibliography 436

Appendix A Common Abbreviations and Acronyms 439

Appendix B Definition of Soil and Groundwater Remediation Technologies 445

Appendix C Structures and Properties of Important Organic Pollutants in Soil and Groundwater 451

Appendix D Unit Conversion Factors 459

Appendix E Answers to Selected Problems 461

Index 465

IUPAC Periodic Table of the Elements 477