This open access book synthesizes important advances in the assessment and management of soil and groundwater systems contaminated with petroleum hydrocarbons, especially in the form of light non-aqueous phase liquids (LNAPLs). LNAPL characterization and remediation is challenging due to the multi-phase, multi-component nature of the problem and the various physical, chemical, and biological processes involved in a dynamic and heterogeneous hydrogeological setting. This book focuses on the current state of practice of LNAPL characterization and remediation and seeks to provide information and a framework that would allow some of these complexities to be better addressed by contaminated land practitioners, researchers, and regulators.

There are many global environmental issues that are directly related to varying levels of contamination from both inorganic and organic contaminants. These affect the quality of drinking water, food, soil, aquatic ecosystems, urban systems, agricultural systems and natural habitats. This has led to the development of assessment methods and remediation strategies to identify, reduce, remove or contain contaminant loadings from these systems using various natural or engineered technologies. In most cases, these strategies utilize interdisciplinary approaches that rely on chemistry, ecology, toxicology, hydrology, modeling and engineering. This book series provides an outlet to summarize environmental contamination related topics that provide a path forward in understanding the current state and mitigation, both regionally and globally. Topic areas may include, but are not limited to, Environmental Fate and Effects, Environmental Effects Monitoring, Water Re-use, Waste Management, Food Safety, Ecological Restoration, Remediation of Contaminated Sites, Analytical Methodology, and Climate Change.

Preface

Petroleum hydrocarbons (PHCs) are among the most common and widespread contaminants in urban and industrial environments. Following a release from containment facilities, these complex mixtures of organic compounds can be found as nonaqueous phase liquids (NAPLs) in the subsurface, where they may act as a persistent source of contamination for soil and groundwater systems. Common petroleum fuels such as petrol (gasoline), diesel, and kerosene-type jet fuel are lighter-than-water NAPLs (LNAPLs).

Subsurface characterisation and remediation of sites contaminated with PHCs is often challenging due to the multi-fluid, multi-component nature of the problem and the various physical, chemical, and biological processes involved in a dynamic and naturally heterogeneous hydrogeological setting. Establishing an effective and sustainable strategy to manage risks posed by PHCs must be done considering all stakeholders and existing regulatory framework.

The objective of this book is to give visibility to advances in the characterisation and remediation of PHC-impacted sites, as well as pertinent concepts and methods that may still be underutilised by the remediation industry internationally. Potential future lines of research and development as well as best practices that provide guidance to contaminated land practitioners are presented throughout the book.

The book contains three sections: Chaps. 1–6 mainly address understanding and analysing the fate and transport of PHCs in the subsurface; Chaps. 7–11 focus on site characterisation tools; and Chaps. 12–18 discuss in situ remediation technologies and site management strategies.

In the first section, Chap. 1 serves as an introduction to the rest of the book and presents an overview of the main challenges found in PHC-contaminated sites. Chapter 2 critically underpins our assessment of LNAPL distribution by examining the historical development of constitutive relationships between water, LNAPL, and air governed by fluid saturations and capillary pressures. Chapter 3 shows in more detail how these constitutive relationships enable the estimation of subsurface LNAPL volumes, in particular in unconsolidated media with multi-modal pore distributions. Chapter 4 further explores the effects of subsurface heterogeneity on LNAPL distribution by discussing the application of geological-based sequence stratigraphy to both site investigation and remediation. Chapter 5 focuses on natural source zone depletion (NSZD) mechanisms, which are essential to understand the fate and transport of petroleum NAPLs. Lastly, Chap. 6 addresses petroleum vapour intrusion and the risks linked to it.

In the second section, Chap. 7 discusses high-resolution site characterisation (HRSC) approaches for the investigation of subsurface physical properties by using direct push, nuclear magnetic resonance (NMR), and groundwater tracing technologies, and Chap. 8 focuses on high-resolution targeted NAPL delineation methods. Chapter 9 explains the influence of PHC biodegradation on geophysical measurements and how biogeophysics can contribute to optimise site investigation outcomes. Chapters 10 and 11 consider, respectively, the use of molecular biological tools (MBTs) and compound-specific isotope analysis (CSIA) to determine the presence and activity of PHC-degrading microorganisms and assess remediation performance.

In the third section, each chapter examines the application of different in situ remediation technologies. Chapter 12 evaluates the utility and challenges of estimating LNAPL transmissivity and implementing hydraulic recovery systems. Chapter 13 deliberates how NSZD can be incorporated into a site management strategy. Chapter 14 stresses the continued central role of bioremediation. Chapter 15 examines the range of in situ chemical oxidation (ISCO) possibilities. Chapter 16 explores the use of activated carbon injectates as a sorptive and treatment substrate. Chapter 17 discusses the novel application of foams as a remediation and blocking agent. Chapter 18 presents advances in low-temperature thermal remediation.

Not all topics could be covered and more could have been included regarding certain subjects (e.g. sustainability and resiliency considerations for site management, cutting-edge laboratory analytical techniques, or assessment of risks posed by PHC biodegradation by-products), but we hope this book will contribute to the increased adoption of improved theories and methods within our industry and promote further research in the fields of contaminated site characterisation and in situ remediation.