Chapter 17 Advances in the Determination of Soil Moisture Content

This chapter discusses some advanced methods that are used to extract information from electrical signals, and how this could be used to predict soil moisture content. A brief explanation of what is meant by signal and various signal processing techniques, either by summation of elemental signals (synthesis) or by decomposition into elemental signals (analysis), is discussed. To demonstrate the synthesis methods, pulse and sinusoid signals are applied; whereas, for decomposition analysis, both time domain and frequency domain analyses are discussed. In frequency domain analysis of signals the use of the Time Domain Reflectometry (TDR) and Fourier spectral analysis to predict soil moisture content and salt concentration is demonstrated. Unlike Fourier decomposition, which partitions signals based on harmonic frequencies by using parametric sines and cosines, eigen-decomposition analysis, separates signal components by differences in their power. These methods are applied in several case studies for the determination of soil moisture content, soil density, clay content, salt concentration, and organic fluid content. In addition, a Neuro-Fuzzy Logic method of analysis, which simply uses both neural networks and fuzzy logic, is discussed. To demonstrate the use of this method to predict soil moisture content, the changes in spectral magnitude and phase angle of the tested soil systems were considered as specific signatures for different soil conditions and were used to train Neuro-Fuzzy Logic models. This method of analysis provided a powerful design technique that combines the ability to learn from data sets, the transparent representation of knowledge acquired, and the ability to cope with uncertainties

Chapter 7 Soil and Contaminant Interaction

This chapter provides details of the complex interactions of the soil constituents and the chemicals that may exist in situ or find their way into a soil. These interactions have important implications for studies and predictions of the movement of contaminants in the subsurface environment as adsorption and other soil-contaminant binding mechanisms may affect the hydraulic conductivity of a geologic medium. Whereas the binding of chemicals on soils solid surfaces may render groundwater remediation techniques ineffective, other chemical and biological processes can provide natural attenuation of contaminated sites. The chapter begins with the commonly used methods to determine the amount of a solute bound by matrix surfaces by Freundich and Langmuir isotherms, together with a discussion of the S-, L-, H-, C-curve isotherms, as well as more advanced descriptions of multicomponent adsorption. Subsequently, the theories by Gouy-Chapman and Stern are presented together with detailed calculations of the electrical charges on the surface of clays, in the Stern layer and the diffuse layer. A brief introduction of first- and second-order kinetics is presented, followed by a detailed exposition of metal cation adsorption, organic contaminant-soil interaction, and of the biological processes that may lead to natural attenuation

Chapter 5 Groundwater

This chapter presents an introduction to the basic concepts and developments in the study of flow of water in the subsurface environment. The importance of groundwater as a natural freshwater reserve and for the public health is initially described. The relation between groundwater extraction and land subsidence is discussed, as well as the problems of coastal saltwater intrusion. Subsequently, an exposition is presented of the basic groundwater flow equations that include Darcy\u27s law and the continuity equation. Flow in fractured rocks is briefly discussed together with the cubic law that describes the velocity in such media. The concept of the effective hydraulic conductivity is introduced through the flow in stratified aquifers, followed by the mathematical exposition of one-dimensional (1-D) flow in confined and unconfined aquifers. Applications are provided for the cases of flow through earth dams, aquifers under rain, and groundwater flow to streams. The final part of this chapter introduces some basic concepts and solutions from well hydraulics. Steady-state flow to wells in confined and unconfined aquifer, the method of images, and De Glee\u27s solution for leaky aquifers are presented. The chapter concludes with an exposition of issues related to construction dewatering

Fundamentals of Geoenvironmental Engineering: Understanding Soil, Water, and Pollutant Interaction and Transport

© 2018 Elsevier Inc. All rights reserved. Fundamentals of Geoenvironmental Engineering: Understanding Soil, Water, and Pollutant Interaction and Transport examines soil-water-pollutant interaction, including physico-chemical processes that occur when soil is exposed to various contaminants. Soil characteristics relevant to remedial techniques are explored, providing foundations for the correct process selection. Built upon the authors\u27 extensive experience in research and practice, the book updates and expands the content to include current processes and pollutants. The book discusses propagation of soil pollution and soil characteristics relevant to remedial techniques. Practicing geotechnical and environmental engineers can apply the theory and case studies in the book directly to current projects. The book first discusses the stages of economic development and their connections to the sustainability of the environment. Subsequent chapters cover waste and its management, soil systems, soil-water and soil-pollutant interactions, subsurface transport of pollutants, role of groundwater, nano-, micro- and biologic pollutants, soil characteristics that impact pollution diffusion, and potential remediation processes like mechanical, electric, magnetic, hydraulic and dielectric permittivity of soils. Presents a clear understanding of the propagation of pollutants in soils. Identifies the physico-chemical processes in soils. Covers emerging pollutants (nano-, micro- and biologic contaminants). Features in-depth coverage of hydraulic, electrical, magnetic and dielectric permittivity characteristics of soils and their impact on remedial technologies

Chapter 2 Sources and Characteristics of Wastes

The technological, industrial, agricultural, and medical discoveries of the 20th century and their massive application to daily life products have created a historically unprecedented economic prosperity to large segments of the human population. The negative by-product of all modern economic activities is the generation of huge volumes of waste. Fertilizers and pesticides that helped trigger the agricultural revolution and the steady supply of food to societies, at the same time have become responsible for the significant deterioration of the environment. Extraction of natural resources, industrial processing, and utilization of those resources have led to serious environmental pollution problems in all phases of their economic life. Thus rock materials, for housing purposes; metals, on which many of our daily products are based on; and petroleum products, which span a wide range of products, from toothpaste to clothing to gasoline have generated, during processing and disposal, pollution problems to air, soil, and water. The magnitude of these problems, be it the ever-increasing volume of waste, or the effect on ecosystems and human health surpasses the scientific and technological capabilities of current societies. The current chapter provides an overview of the economic activities and processes that constitute the main sources of waste, as well as the characteristics of the generated waste. This will set the stage for the subsequent chapter where the existing regulations and their proposed amendments will be discussed in order to put into perspective the environmental regulatory trends and the attempts in several countries to reach a stage, where economic development can coexist with the protection of the environment

Chapter 16 Dielectric Permittivity and Moisture Content

This chapter discusses the concept of soil dielectrics, available techniques for the determination of soil dielectric permittivity and soil moisture content, and the associated theoretical background for a better understanding of the measured soil dielectric property and the moisture content. The design stages of the Time Domain Reflectometry (TDR) system and the methods used to characterize the reflected signal are discussed. Important probe design factors, such as probe length, rod diameter, spacing between the rods, sampling volume, connector type, connector correction, and probe robustness, that influence the reflected signals are evaluated. Laboratory measurement techniques for dielectric permittivity and bulk electrical conductivity are also deliberated. These two properties are often obtained by direct analysis of the TDR waveforms in the time domain. However, since much more information is contained in TDR waveforms, using the extended Debye model, the inverse modeling of TDR waveform to extract information about the frequency dependence of the soil dielectric permittivity, is explained. To represent the macroscopic dielectric property of a soil by its individual components, the widely used mixing models that relate dielectric constant and soil moisture content, are assessed. The influences of physicochemical properties, such as bound water content, capillary and free water, saline water solution, mineralogy, bentonite content, clay content, soil texture, moisture content, soil density, volcanic soils, and nonaqueous phase liquid solutions, on dielectric permittivity of soils are analyzed. The various moisture content prediction models such as empirical models, dielectric mixing, and physical models, are discussed. The impact of the physicochemical soil parameters on the validity of these models is also emphasized

Chapter 8 Fate and Effects of Pollutants on the Land Environment

This chapter discusses initially the different pathways (soils, sediments, water, and air) through which contaminants are transported and become available to organisms and people posing health risks. The concept of bioavailability, the physical, chemical, and biological processes that define the exposure of plants and animals to chemicals is discussed as it relates to different scientific disciplines. Inorganic and organic contaminants can be retained in soils and sediments, and hence not available to living organisms under variable conditions. The chapter details further the main mechanisms of retention of different classes of chemicals, the conditions under which they can be immobilized or become mobile and travel within the water, and the type of soil material that can react and retain chemicals. The chapter discusses also the ecotoxicological hazard potential of contaminants by detailing their most important physicochemical, fate and effect parameters, and some of the methods to determine them. Calculations are also provided through the hazard quotient risk tool for persistent organic pollutants (POPs), which enables risk-based analyses to prioritize and manage POPs and other hazardous substance contaminated sites. Finally, the chapter concludes with a discussion on particulate matter, its sources and health effects, and ambient air quality standards

Chapter 3 Management of Wastes: An International Prospective

Hazardous waste needs to be carefully managed and disposed of as the material classified under this category can ignite, or explode, or react violently with water, air, and other substances, or corrode the drums that the waste is transported or temporarily stored in. Some of this material may also be carcinogenic, or toxic to humans or the environment, infectious, or even present the risk of creating mutations. Because of the danger that hazardous wastes pose, environmental management and regulations, in all phases of their life, are very detailed and stringent in most countries. The United States was the first to enact a comprehensive framework of regulations on hazardous waste with the landmark acts of Resource Conservation and Recovery Act (RCRA) and Comprehensive Environmental Response, Compensation and Liabilities Act (CERCLA). These important pieces of environmental legislations are discussed in detail in order to demonstrate both the complexity of protecting the environment and human populations, and the challenges, but also the trends in waste minimization and disposal. The design criteria and the elements of the disposal facilities for these types of wastes are also discussed here. In addition, the main elements of related pieces of legislation in Canada and in Europe are described and comparisons are provided between the regulatory acts in the United States, Canada, and Europe. This will help the reader realize that environmental legislation in advanced countries shares similar elements, frequently borrowing important insights from another country\u27s regulations, as well as the future trends. Finally, the chapter concludes with a brief exposition of the management and disposal of the most dangerous type of waste that of radioactive waste

Chapter 13 Hydraulic Properties of Soils

This chapter addresses the hydraulic properties of soils, which are primarily expressed through the concept of the hydraulic conductivity parameter in Darcy\u27s law. In that respect, it is a companion to Chapter 5 of this book, which provides the background for the material discussed here. Initially, different models to estimate the hydraulic conductivity are presented, followed by laboratory methods of its estimation. The scale effect is particularly emphasized, the discrepancy that has been observed between laboratory and field estimates of hydraulic conductivity, which may range over several orders of magnitude. Field tests, through the pumping of wells in aquifers, are extensively presented. Steady-state solutions are initially discussed, followed subsequently by methods to assess the hydraulic parameters when the test, as is in most cases, has not reached equilibrium flow conditions. Transient radial flow to a well in a confined aquifer is presented through the Theis and the Cooper-Jacob methods. In addition, the Hantush-Jacob method for leaky aquifers, and the Neuman method for pumping tests in unconfined aquifers are described. The chapter also discusses the physical and chemical factors that affect the hydraulic properties of clay mixtures that are used as engineered barriers such as the heterogeneity, soil structure and composition, fracturing, and adsorption capacity, among others. It concludes with the effect that inorganic and organic contaminants may have on the hydraulic properties of soil-based engineered barriers