Table Of ContentPhysicochemical Groundwater
Remediation
Physicochemical Groundwater
Remediation
Edited by
James A. Smith
and
Susan E. Burns
Department of Civil Engineering
University of Virginia
Charlottesville, Virginia
KLUWER ACADEMIC PUBLISHERS
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Preface
Timely and cost-effective restoration of contaminated soil and
groundwater continues to be one of the most challenging problems facing
environmental scientists and engineers. Remediation of contaminated
subsurface environments is a multi-billion dollar business owing to years of
improper waste management and disposal practices at tens of thousands of
sites around the globe, and the current absence of technologies to effectively
clean many of these sites.
Several factors contribute to our inability to remediate contaminated
subsurface environments. First, subsurface heterogeneities often create
regions of low water permeability. Over long periods of contaminant release
to the subsurface, pollutants can diffuse into these low-permeability zones.
When a conventional remediation technology such as pump-and-treat is
applied, pollutants must diffuse back out of these low-permeability zones
before they can be captured by the pump-and-treat system. Second,
pollutants may desorb slowly from natural soil, or, in cases of gross
subsurface contamination, pollutants may be present as nonaqueous phase
organic liquids (NAPLs). For these cases, remediation efforts may be further
limited by pollutant desorption and/or dissolution rates. Many organic
pollutants are highly resistant to biodegradation or chemical transformation
under natural conditions, and usually cannot be transformed unless present in
the aqueous phase. Oftentimes, groundwater is contaminated by a variety of
organic and inorganic pollutants, and a remediation technology that works
well for one pollutant may not be appropriate for another. When pump-and-
treat remediation systems are used, they are rarely designed for optimum
performance.
Most of us would agree that much work remains to be done. As we
transition intothe 21stcentury, it is also apparent that this is an exciting time
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vi Preface
for engineers and scientists studying remediation technologies. Our research
activities of the past and next 10 years will have a dramatic impact on the
quality ofthe subsurface environment for the next century. In 20, or even 10
years from now, our approach to subsurface remediation will probably be
vastly different than it is today. Many of the emerging technologies
presented here will form the basis ofstandard remediation practices.
The first two chapters of this book address the design of pump-and-
treat systems for remediation and/or containment of contaminated
groundwater. Using powerful optimization algorithms built on top of
conventional flow and solute-transport models, groups from the University
of Massachusetts and the University of Virginia demonstrate the optimal
design ofpump-and-treat remediation systems. Using appropriate constraints
and penalty functions, the optimization algorithms efficiently search for the
optimal system design with regard to variables such as well pumping rate,
well location, and management periods. These relatively inexpensive
simulations can significantly reduce the cost and improve the effectiveness
ofpump-and-treat remediation technologies.
Chapters 3 through 5 present emerging technologies for chemical,
electrochemical, and biochemical remediation processes. Munakata and
Reinhard from Stanford University discuss the advantages and limitations of
palladium catalysts for the reductive dehalogenation and hydrogenation ofa
variety of contaminants in wastewater. Researchers from Northeastern
University and the U.S. Environmental Protection Agency discuss the
transport and degradation of groundwater pollutants subjected to electric
fields and include a discussion of the mobilization of pollutants from low-
permeability media.
Chapters 6 through 8 focus on the use of sorptive and reactive in situ
treatment walls. Alan Rabideau and his co-workers begin this series with an
overview of sorptive vertical barrier technologies. They explore both low-
and high-permeability systems and present two case studies of barrier
performance. Baolin Deng and Shaodong Hu from New Mexico Tech
discuss the reaction rates of chlorinated solvents on zero-valent iron
surfaces. Their analyses will help guide future designs of these reactive
treatment walls. Robert Bowman and his co-workers describe a pilot-scale
test of a permeable, sorbing treatment wall composed of a surfactant-
modified zeolite at the Large Experimental Aquifer Facility of the Oregon
Graduate Institute. In this study, they observe and analyze problems
associated with permeability reductions inthe treatment zone.
Surfactant-enhanced aquifer remediation for both sorbed pollutants and
nonaqueous phase liquids is addressed in Chapters 9 through 13. Chapters 9
and 10 discuss the effects of surfactants on the sorption of organic
contaminants to natural soil. Seok-Oh Ko and co-workers present data on the
equilibrium distribution ofpollutants in the presence ofsurfactants, whereas
James Deitsch and Elizabeth Rockaway discuss how surfactants can increase
Preface vii
a pollutant’s desorption rate by increasing the desorption mass-transfer
coefficient and the desorption concentration gradient. In Chapter 11, Wu and
co-workers from the University of Oklahoma discuss surfactant selection for
separate-phase oil removal from the subsurface. They demonstrate that
surfactant hydrophobicity should relate to oil hydrophobicity, and they
describe a method to quantify the hydrophobicity of multicomponent
nonaqueous phase liquids. In the next chapter, Kibbey and co-workers
examine the use of surfactant/alcohol mixtures to reduce the density of
nonaqueous phase liquids prior to their mobilization. This approach prevents
downward migration of the nonaqueous phase liquid and possible
complications with its extraction from the subsurface. In Chapter 13, Taylor
and Pennell from Georgia Tech report on the use of surfactant/ethanol
formulations to increase the solubilization of nonaqueous phase
tetrachloroethene.
Finally, Chapters 14 and 15 address the remediation of the unsaturated
zone. In Chapter 14, researchers from the University of Virginia study the
effects of natural atmospheric pressure variations on the flow of air into and
out of the unsaturated zone at the Picatinny Arsenal in northern New Jersey.
This “barometric pumping” contributes to the natural remediation of the
shallow, trichloroethylene-contaminated groundwater. In the last chapter of
the book, Richard Meixner and co-workers present a detailed field study
documenting the effectiveness of soil-vapor extraction to remediate gasoline
hydrocarbons in the unsaturated zone.
Acknowledgements
The “seed” for this book was planted at a meeting ofthe WaterQuality
committee of the Hydrology Section of the American Geophysical Union
(AGU) sometime in late 1997. At that meeting, we proposed to the
committee a special session on “Physicochemical Remediation of the
Subsurface Environment”. Based on the favorable response of the
committee, we moved forward with this special session for the Fall ’98 AGU
meeting in San Francisco, and our seed had taken root. The session was
highly successful, and the discussions were lively and interesting. It was
apparent to us that ideas for many new and exciting physicochemical
remediation technologies were developing and growing. Following the
meeting, we contacted participants in the session and other experts in this
subject area and invited them to contribute a chapter to the book you are
reading today. We think you will find an impressive array of research results
and analyses herein. All of the chapters submitted to us were critically
reviewed by two or more anonymous peer reviewers, and only the most
favorably reviewed submissions were included in this book. As a result of
this multi-stage review process (beginning back at that first AGU Water
Quality committee meeting), we think that our early efforts have grown into
a valuable book for practicing environmental scientists and engineers,
environmental decision makers, and environmental researchers in academia
and government.
To this end, we thank the members of the AGU Water Quality
committee for encouraging us to proceed with our original idea. We also
thank the many participants of the Fall ’98 session for their presentations and
lively discussions, and for their enthusiasm for extending the session topic
into a refereeed book. Certainly, this book would not have been possible
without the high-quality contributions of each of the author groups and the
ix
x Acknowledgments
careful technical evaluations of the anonymous reviewers. We offer all of
you a sincere “thank you” for your hard work.
James A. Smith
Susan E. Burns
Contents
Dynamic Optimal Design ofGroundwater Remediation using Genetic
Algorithms 1
AMYCHANHILTON,AYSEGULAKSOY,ANDTERESAB. CULVER
Optimal Plume Capture Design in Unconfined Aquifers 23
ANN E. MULLIGAN AND DAVID P. AHLFELD
Palladium Catalysis forthe Treatment ofContaminated Waters:
A Review 45
NAOKO MUNAKATA AND MARTIN REINHARD
Electrochemical and Biogeochemical Interactions underDC
Electric Fields 73
AKRAM N. ALSHAWABKEH AND KRISHNANAND MAILLACHERUVU
Transport ofTrichloroethylene (TCE) in Natural Soil by
Electroosmosis 91
SOUHAILR.AL-ABEDANDJIANN-LONGCHEN
Sorbing Vertical Barriers 115
ALANJ.RABIDEAU,JOHNVAN BENSCHOTEN, ASHUTOSHKHANDELWAL,
ANDCRAIGR.REPP
Reductive Dechlorination ofChlorinated Solvents on Zerovalent
Iron Surfaces 139
BAOLINDENG AND SHAODONGHU
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Pilot Test ofa Surfactant-Modified Zeolite Permeable Barrier for
Groundwater Remediation 161
ROBERTS.BOWMAN, ZHAOHUILI,STEPHENJ.ROY,TODDBURT,
TIMOTHYL.JOHNSON, AND RICHARDL.JOHNSON
Effects ofSurfactant Sorption on the Equilibrium Distribution of
Organic Pollutants inContaminated Subsurface Environments 187
SEOK-OHKo,MARKA.SCHLAUTMAN,ANDELIZABETHR.CARRAWAY
Surfactant-Enhanced Desorption ofOrganic Pollutants from
Natural Soil 217
JAMESJ.DEITSCHANDELIZABETHJ.ROCKAWAY
Surfactant-Enhanced Removal ofHydrophobic Oils from
Source Zones 245
BINWU,HEFACHENG,JEFFREYD.CHILDS,ANDDAVIDA.SABATINI
In Situ Density Modification ofEntrapped Dense Nonaqueous-Phase
Liquids (DNAPLs) using Surfactant/Alcohol Solutions 271
TOHRENC. G. KlBBEY, C. ANDREWRAMSBURG,KURTD. PENNELL,
ANDKIMF. HAYES
Effects ofCosolvent Addition on Surfactant Enhanced Recovery of
Tetrachloroethene (PCE) from a Heterogeneous Porous Medium 285
TAMMYP. TAYLOR AND KURTD. PENNELL
Unsaturated-Zone Airflow: Implications for Natural Remediation
ofGround Water by Contaminant Transport through
the Subsurface 307
FREDD.TILLMAN,JR.,JEE-WONCHOI,WHITNEYKATCHMARK,
JAMESA. SMITH, AND HOUSTONG. WOOD,III
High-Vacuum Soil Vapor Extraction in a Silty-Clay Vadose Zone 341
RICHARDE. MEIXNER,RICHARDHEIBEL, AND JAMESE. SADLER
Contributors 361
Index 365
