Cover: Soil and Groundwater Remediation by Chunlong (Carl) Zhang

Soil and Groundwater Remediation

Fundamentals, Practices, and Sustainability

Chunlong (Carl) Zhang, Ph.D., PE

College of Science and Engineering,
University of Houston‐Clear Lake,
Houston, TX, USA

No alt text required.

To my mother Yunfeng Pan (1926–2018)
To my wife Sue and sons Richard and Arnold

About the Author

Dr. Zhang is a professor of environmental science at the College of Science and Engineering, University of Houston‐Clear Lake. He has a combined three decades of experience in academia, industries, and consulting in the environmental field. He is the author and co‐author of more than 150 papers, proceedings, and technical reports in diverse areas including contaminant fate and transport, environmental remediation, sampling and analysis, and environmental assessment. In his current position at the University of Houston, he lectures extensively in the area of environmental chemistry, environmental sampling and analysis, soil and groundwater remediation, and environmental engineering at both the undergraduate and graduate levels. He is the author of the popular textbook “Fundamentals of Environmental Sampling and Analysis” published by Wiley in 2007. His expertise includes a variety of practical experience in both field and lab on contaminant behavior in soil and groundwater, emerging chemical analysis, and remediation feasibility studies. Dr. Zhang is a registered professional engineer in environmental engineering. He also serves as an adjunct professor in the College of Environmental and Resource Sciences at Zhejiang University.


This book is written primarily to equip our undergraduate and graduate students with essential knowledge in the field of soil and groundwater remediation (SGWR). Current environmental science and engineering curriculums in most universities have well‐established course work in the traditional fields of air pollution control, water/wastewater and solid/hazardous waste treatment and disposal. That is obviously not the case for this equally important field of soil and groundwater remediation. Clean air, surface water, soil, and groundwater are all essential to the quality of our life.

SGWR has emerged and it has become an increasingly important and popular topic since the 1980s. SGWR or its equivalent courses are becoming required or elective courses for students at both the undergraduate and graduate levels in many universities, especially in the North America and European countries where sufficient experience has been accumulated following the decades‐long research and development of remediation techniques at various contaminated sites. These sites have received public scrutiny since the 1950s and the remediation technologies started to be developed and implemented since then. The issue of contaminated soil and groundwater has also become increasingly important in many developing countries in the recent decade because of contaminated sites associated with the rapid economic development in Asia and Latin America.

Unfortunately, there is no book that can be considered as a suitable “textbook” for this increasingly important subject. The development of this textbook is to fill this gap. As a textbook, it introduces the underlying principles and essential components of soil and groundwater remediation in a comprehensible but not overwhelming manner. Ample numbers of worked and practice problems are included toward the understanding of fundamental chemistry, microbiology and hydrogeology, practical applications, easy‐to‐understand design equations, and calculations to be useful in preparing our students for the workplace in the environmental remediation industries. In addition to the principles and practices, sustainable remediation is also the theme of this textbook. It is expected that this book will serve as a single source for an instructor to introduce this interdisciplinary subject, including chemical fate and transport, hydrogeology, regulations, cost analysis, risk assessment, site characterization, modeling, and various conventional and innovative remediation technologies.

Chapter 1 serves as an introductory chapter in describing the importance of groundwater resource, groundwater quality, contaminant sources and types from both the US and the global perspectives, and the scope of soil and groundwater remediation. Chapter 2 introduces frequent soil and groundwater contaminants and their fate and transport processes in the subsurface environment, including abiotic and biotic chemical processes, interphase and intraphase chemical movement. Chapter 3 provides some essential background information for readers to understand basic soil and aquifer properties, groundwater wells, and equations in describing groundwater flow under various conditions. Chapter 4 introduces three separate but all essential components of SGWR, i.e. the regulatory framework as a driving force to site cleanup, the cost analysis for the comparison of remedial scenarios, and the risk assessment to help define the cleanup goal. Chapter 5 introduces the methodology to characterize contaminated sites, field techniques to survey soil/geological/hydrogeological parameters, soil and groundwater sampling, and analysis of subsurface contaminants. Chapter 6 provides a general framework for the development of site‐specific remediation technologies, a screening matrix for the selection of remediation technologies, and an overview of various SGWR technologies.

The next six chapters will detail soil and groundwater remediation technologies that are in the common practice in remediation industries. Each chapter will accompany with case studies and example design calculations whenever appropriate. Chapter 7 introduces pump‐and‐treat systems with a focus on design equations on the belowground capture zone and aboveground treatment using air stripping and activated carbon adsorption. The conditions of why conventional pump‐and‐treat systems work/do not work, and how to improve pump‐and‐treat are discussed. Chapter 8 describes soil vapor behavior and gas flow in the subsurface, and how to use design equations to determine well number, flow rate, and well locations. Chapter 9 is devoted to bioremediation and environmental biotechnology in general. The fundamentals of bacterial growth, stoichiometry, kinetics, pathways, and optimal conditions are delineated first, followed by various bioremediation/biotechnology applications such as in situ and ex situ biological treatment, landfills, and phytoremediation. Design calculations such as nutrient/oxygen delivery for bioremediation and landfill design basics will be discussed. Chapter 10 introduces thermally enhanced remediation (i.e. use of hot air, steam, hot water, and electro‐heating) and thermal destruction (vitrification and incineration). Practical design calculations that focus primarily on incinerators are included. Chapter 11 discusses the principles, applications, design, and cost‐effectiveness of soil washing and in situ soil flushing using water, surfactants, and cosolvents. Chapter 12 describes the chemical reaction mechanisms, hydraulics, configuration, design, and construction of permeable reactive barriers.

The last chapter (Chapter 13) is dedicated to the basics about modeling of groundwater flow and contaminant transport. Our focus will be the Darcy's law and mass balance approach in developing the governing equations for groundwater flow in saturated and unsaturated zones (e.g. the Laplace equation and the Richards equation). This is followed by the same approach in the development of governing equations for contaminant transport in saturated and unsaturated zones, with the consideration of advection, dispersion, adsorption, and reaction, as well as more complicated multiphase flow and transport. Finally, the analytical solutions to several simplified flow and transport processes are provided, followed by the mathematical framework in reaching the numerical solutions.

This book is unique in several aspects to serve as a textbook for senior undergraduate and graduate students, as well as a valuable reference book for general audiences. Several approaches are used to ensure the book for a wide usage of readers. (i) Each chapter will have a set of learning objectives, and the discussion of key theories/principles followed by example problems will be provided to help readers' understanding of subjects for classroom use. (ii) When remediation techniques are introduced, case studies will be provided so readers can relate the principles to the applications of relevant remediation techniques. (iii) End‐of‐Chapter Questions and Problems are included to further help understand the materials. (iv) Supplemental materials are provided in the format of Box in each chapter, such as Superfund sites versus Brown fields, emerging contaminants, hydraulic head, and Bernoulli's equation, and terms relevant to environmental legislature. In Chapters 7 through 12, a particular emphasis is placed on the best management practices and green/sustainable remediation in Box format. (v) A bibliography is given at the end of each chapter for those who need specific details from guidelines (e.g. EPA) or recent development from peer‐reviewed journal articles. This list of references is intended to provide an up‐to‐date or in‐depth discussion of remediation topics, such that researchers and experienced remediation practitioners will also find it to be useful.

This book should be an appropriate textbook for a Soil and Groundwater Remediation course perhaps with various focuses and variations depending on the specific discipline, such as Soil and Groundwater Restoration, Groundwater Engineering, Environmental Remediation/Restoration, Remediation Technologies, Remediation/Environmental Geotechnics, Reclamation of Contaminated Land, Site Remediation Technologies, and Site Assessment and Remediation. This book is also appropriate for use as reference or supplemental material for courses such as Environmental Geology, Applied Hydrogeology, Subsurface Fate and Transport, Environmental Engineering, and Groundwater Contamination. Besides a textbook, this book should also be appropriate as a single source reference for environmental professionals to quickly grasp the fundamental principles, practices, and sustainable concepts of soil and groundwater remediation. As a single source, the readers can comprehend the basic science and engineering principles related to site remediation without going into numerous detailed standard methods, handbooks, and technical reports currently available from various sources.

The author will be happy to receive comments and suggestions about this book at his e‐mail address:

January 2019
Chunlong (Carl) Zhang
Houston, TX, USA


Materials of this book have been used in several courses at the University of Houston. I first would like to thank my students for their comments, suggestions, and encouragement. These feedbacks are typically not technically detailed, but help me immeasurably to improve its readability. Certainly I would like to thank technical reviewers for the review of this book from the beginning to the final draft, including Dr. K.J. Reimer of the Royal Military College of Canada, Dr. Ming Zhang, Geological Survey of Japan, Dr. W. Andrew Jackson, Texas Tech University, Dr. Jianying Zhang, Zhejiang University, and a dozen of anonymous reviewers at the U.S. EPA, Argonne National Laboratory, environmental consulting firms, and academia.

My special thanks to Wiley’s Executive Editors Mr. Bob Esposito and Mr. Michael Leventhal for their vision and guidance of this project. Ms. Beryl Mesiadas, Project Editor has been very helpful in insuring me the right format of this writing even from the beginning of this project. Thanks to the Production Editor Ms. Gayathree Sekar who exhibited dedicated assistance throughout the production process of the book. It has been a pleasant experience in working with this editorial team of high professional standards and experience.

This book would not be accomplished without the support and love of my wife Sue and the joys and emotions I have shared with my two sons, Richard and Arnold. Even during many hours of my absence in the past years for this project, I felt the drive and inspiration. This book is written as a return for their love and encouragement. With that, I felt at some points the obligation of fulfilling and delivering what is beyond my capability.

Whom This Book Is Written For

College students and graduate students are the primary targeted readers of this book. Suitable readers who are routinely involved in various aspects of soil and groundwater remediation may include project managers, field personnel, hydrogeologists, monitoring personnel, remediation investigators/engineers, environmental consultants, regulatory personnel, environmental attorneys, expert witness, industrial compliance officers, industrial hygienists, occupational health professionals, and managers/supervisors who will interact with remediation personnel on a daily basis. Other interested readers may also include allied disciplines such as applied chemists, microbiologists, toxicologists, hydrologists, soil scientists, statisticians, universities researchers, and site owners and professionals in various industries for regulatory compliance.

To the Instructor

This book is designed to have more materials than needed for a one‐semester course. It can be taught as a one‐semester course with various focuses and selected chapters depending on the specific need. For example, not all the remediation technologies in Chapters 7 through 12 should be taught, and Chapter 13 regarding the modeling of flow and transport can be generally disregarded at the undergraduate level. In properly using this text, instructors are provided with a solution manual and lecture slides through Wiley. Students and readers of other interesting groups may also find the answers to selected problems at the end of this book. For visual learners, additional audiovisual links can be found through the book Web site from Wiley, located at A word of caution is the unit system used in this book. The International System of Units (SI) is used with US units in parenthesis where appropriate. This makes the book useful to professionals outside the United States and to those within the United States.

List of Symbols

Letters Symbols

1/n Freundlich isotherm constant
A Area (m2)
ABS Absorption rate for dust (%)
AT Averaging time of exposure (years)
b Thickness of a confined aquifer or saturated thickness of an unconfined aquifer (m)
b Reactive cell thickness (m)
BCF Bioconcentration factor (L/kg)
BR Breathing rate for dust (%)
BW Body weight (kg)
C Concentration in water (mg/L), air (mg/m3), or soil/dust (mg/kg)
C Weight percentage of carbon (%)
C Cost
C A constant in equation
Concentration in adsorbed phase (mg/kg)
CDI Chronic daily intake (mg/kg‐day)
CE Combustion efficiency (%)
CMC Critical micellar concentration (mol/L)
C p Specific heat capacity (J/kg‐K; Btu/lb‐F)
C s Surfactant concentration (mol/L)
CSF Cancer slope factor (mg/kg‐d)−1
d Diameter; Infinitesimally small change (m)
D Molecular diffusion coefficient (m2/s)
D Distance (m)
dC/dx Derivative of concentration with respect to x (concentration gradient)
D e Effective diffusion coefficient (m2/s)
D h Hydrodynamic dispersion (m2/s)
dh The infinitesimally small change in hydraulic head (m)
dh/dl Derivative of head with respect to distance (hydraulic gradient) (unitless)
dl The infinitesimally small change in distance (m)
dq/dA Heat flux (W/m2)
DRE Destruction and removal efficiencies (%)
dx Infinitesimally small change in x coordinate (m)
dz/dx Derivative of head with respect to x (potential head change) (unitless)
E Activation energy (kJ/mol)
E Electrode potential (volt)
e 2.71828
EC Exposure concentration (water: μg/L; air mg/m3)
ED Exposure duration (years)
EF Exposure frequency (days/yr)
ET Evapotranspiration rate (L/day, in‐acre/yr)
erf The error function
exp(x) Exponential of x, exp(x) = ex
f Fraction (soil component, cosolvent, and heat loss) (unitless)
f oc Fraction of organic carbon in soil
FV Future value
f w Fraction of contaminant remaining in soil water
g Gravitational constant (9.81 m/s2)
G Air flow rate (m3/m2‐hr) in a stripping tower
G Gibbs free energy (J)
h Potential head/water level/soil depth (m)
H Henry's law constant: atm/(mg/L), atm/M, atm/(mol/m3), or dimensionless
H Total head/water level (m)
ΔH Enthalpy change (J)
ΔHv Heat of vaporization (J/kg; Btu/lb)
H Weight percentage of hydrogen (%)
h c Heat transfer coefficient (W/m2‐K)
HI Hazard index (dimensionless)
HQ Hazard quotient (dimensionless)
i Interest rate
I Cost index value
IR Intake (ingestion) rate (water: L/d; air: m3/d; soil and dust: kg/d)
J Mass (mole) flux per unit area and time (mg/m2‐s; mol/m2‐h)
k Intrinsic permeability (m2)
k First‐order rate constant (s−1)
k b Biodegradation rate constant (s−1)
K Hydraulic conductivity (m/s)
K Equilibrium constant
K Freundlich isotherm partitioning coefficient
K Thermal conductivity (W/m‐K)
K(θ) Moisture‐dependent unsaturated hydraulic conductivity
K d Soil–water partition coefficient, adsorption coefficient (L/kg)
K L Mass transfer coefficient (m/h), concentration driving force
K La Overall mass transfer coefficient (T−1) in a stripping tower
K m Micelle–water partition coefficient (mol/mol)
K ow Octanol–water partitioning coefficient (unitless)
K sp Solubility product constant
l Distance (m)
L Liquid loading (m3/m2‐hr) in a stripping tower
L Length of a flow path (m)
L Reactive cell thickness (m)
L e Effective length of well screen (m)
m Mass rate (kg/s)
M Mass or mass per unit area (kg, kg/m2)
MW Molecular weight (g/mol)
n Soil porosity (%)
n Number of moles/electrons/years/wells
N Weight percentage of nitrogen (%)
N c Capillary number (dimensionless)
n e Effective soil porosity (%)
NOAEL No‐observed‐adverse‐effect level (mg/kg‐d)
N wells Well number
O Weight percentage of oxygen (%)
P Pressure (atm)/Other properties
P atm Absolute ambient pressure (1 atm or 1.01 × 106 g/cm‐s2)
p i Vapor pressure of component i (atm)
images Vapor pressure of its pure component i (atm)
P r Pressure at a radial distance r from the vapor extraction well (atm)
P RI Pressure at the radius of influence (atm)
PV Present value
P w Absolute pressure at an extraction well (atm or g/cm‐s2)
q Specific discharge (L/day)
Q Volumetric discharge/pumping rate (m3/day, ft3/min)
Q/H Flow rate (cm3/s) per unit thickness of a well screen (cm)
r Radius of well/well casing/well screen/steam influence (m)
R Ideal gas constant (0.082 atm‐L/mol‐K)
R Retardation factor (unitless)
R Groundwater recharge (m3/m2‐day)
R Radius of well screen plus sand pack/gravel envelope (m)
R Stripping factor (unitless)
R acceptable Acceptable removal rate (kg/day)
Re Reynolds number (unitless)
R e The effective radial distance over which y is dissipated (m)
R est Estimated vapor removal rate (kg/day)
RfC Inhalation reference concentration (μg/m3)
RfD Oral reference dose (mg/kg‐d)
R I Radius of influence of a vapor extraction well (m)
R w Radius of a vapor extraction well (m)
s Drawdown (s = h0h) (m)
S Sorbed phase concentration (mg/kg)
S Aquifer storativity (unitless)
S Saturation (%)
S Weight percentage of sulfur (%)
S a Capacity (size) of equipment A
S s Specific storage (m−1)
t Time (s)
t 0.37 Time required for the water level to fall to 37% of the initial change (s)
t 1/2 Half‐life (s)
t D Dimensionless form of time (unitless)
T Absolute temperature in Kelvin (K) or Rankine (R)
T Aquifer transmissivity (m2/day)
TPH Total petroleum hydrocarbons (mg/kg)
u Time parameter in pumping test (dimensionless); arithmetic mean
UF Uncertainty factor (unitless)
UR Unit risk from drinking water (μg/L)−1 and from inhalation (μg/m3)−1
v Darcy velocity/specific discharge/gas flow velocity (m/s)
v c Contaminant velocity (m/s)
v k Kinematic viscosity (m2/d)
v p Groundwater (pore) velocity (m/s)
V Volume (m3)
w Width of an aquifer (x direction) (m)
W(u) Well function
x Distance in the x direction or coordinate (m)
x i Mole fraction of the component i in the mixture
X Amount of chemical to be removed (kg)
y Width of the pumping region (capture zone) (m)
y Distance in the y direction or coordinate (m)
y o Drawdown at time t = 0 (slug test) (m)
y t Drawdown at time t (slug test) (m)
Y Specific yield (%)
Y max Maximum half‐width of the capture zone (m)
images Maximum half‐width of the capture zone at x = 0 (m)
z Distance in the z direction or coordinate (m)
z Packing height of a stripping tower (m)
Z The potential head (the elevation head above mean sea level, MSL) (m)
Gradient operator (m−1)
Latin letter d (pronounced as dee) which denotes partial derivative
∂C/∂t Partial derivative of concentration with respect to time (kg/m3‐s)

Greek Symbols

α Dynamic dispersivity
α Compressibility of an aquifer skeleton
α A scale factor related to the inverse of air entry pressure (cm−1)
β Compressibility of water
γ Interfacial tension between oil and water (dyne/cm)
γ Specific weight (kg/L)
Δ Delta which denotes difference (change in) when precedes symbol
θ Contact angle at the solid–water–NAPL interface
θ a Soil air content (volumetric) (L3/L3)
θ Soil moisture content (volumetric) (L3/L3)
θ r Residual soil water content (L3/L3)
θ s Saturated soil water content (L3/L3)
λ i Molar heat of vaporization (kJ/mol)
μ Dynamic viscosity (M/L‐T; g/cm‐s; dyne×s/cm2)
π 3.14159
ρ Density (g/cm3 or kg/L)
σ Cosolvency power (dimensionless); standard deviation
ψ Tension, suction, or the pressure head
φ Angle (radian)
ω Tortuosity factor (unitless)


* At saturation/equilibrium
Prime symbol (e.g. A′ generally denotes that it is related to or derived from A)
0 Distance/time at 0
0 Standard state
n Grid in the finite difference time domain


a Air
aq Aqueous phase
b Bulk soil
est Estimated
g Gas phase
i ith chemical/node
i In/influent/reactant/feed
i, j, k Three‐dimensional spatial grids along x‐, y‐, and z‐coordinates
n NAPL phase
o Out/Effluent/Product
oct Octanol phase
p Soil particle
p Previous (past) year
s Soil (adsorbed) phase/saturated zone
t Time
T Total
v Void
w Water/well

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