Contaminants In The Subsurface

At hundreds of thousands of commercial, industrial, and military sites across the country, subsurface materials including groundwater are contaminated with chemical waste. The last decade has seen growing interest in using aggressive source remediation technologies to remove contaminants from the subsurface, but there is limited understanding of (1) the effectiveness of these technologies and (2) the overall effect of mass removal on groundwater quality. This report reviews the suite of technologies available for source remediation and their ability to reach a variety of cleanup goals, from meeting regulatory standards for groundwater to reducing costs. The report proposes elements of a protocol for accomplishing source remediation that should enable project managers to decide whether and how to pursue source remediation at their sites.

In this updated and expanded second edition, new literature has been added on contaminant fate in the soil-subsurface environment. In particular, more data on the behavior of inorganic contaminants and on engineered nanomaterials were included, the latter comprising a group of “emerging contaminants” that may reach the soil and subsurface zones. New chapters are devoted to a new perspective of contaminant geochemistry, namely irreversible changes in pristine land and subsurface systems following chemical contamination. Two chapters were added on this topic, focusing attention on the impact of chemical contaminants on the matrix and properties of both liquid and solid phases of soil and subsurface domains. Contaminant impacts on irreversible changes occurring in groundwater are discussed and their irreversible changes on the porous medium solid phase are surveyed. In contrast to the geological time scale controlling natural changes of porous media liquid and solid phases, the time scale associated with chemical pollutant induced changes is far shorter and extends over a “human lifetime scale”.

Combining earth science, subsurface hydrology and environmental geochemistry, this book provides a comprehensive background for those interested in the protection and sustainable management of the subsurface environment. The reader is introduced to the chemistry of contaminants, which usually disturb the natural equilibrium in the subsurface as a result of human activity. One focus of the book is on contaminant reactions in soil solutions. Discussions on case studies are provided.

This volume offers detailed information on the behaviour of various water pollutants, and on the principles and concepts of groundwater flow and transport. It will help readers to understand and execute the planning, supervision, and review of solute transport and groundwater modeling projects. The book also discusses the role and fate of elements that have been identified as major contaminants in surface and subsurface waters, and their adverse effects on ecology and human health. The book explores this theme throughout four sections – a. Understanding Soil-Water Systems, b. Fate and Transport of Pollutants, c. Physico-Chemical Treatment of Wastewater and d. Microbial Techniques Used to Decontaminate Soil-Water Systems. Introducing readers to a range of recent advances concerning the fundamentals of subsurface water treatment, it offers a valuable guide for teachers, researchers, policymakers, and undergraduate and graduate students of hydrology, environmental microbiology, biotechnology and the environmental sciences. It also provides field engineers and industrial practitioners with essential support in the effective remediation and management of polluted sites.

Transport and remediation of subsurface contaminants: introduction; Colloid deposition in porous media and an evaluation of bed-media cleaning techniques; Deposition of colloids in porous media: theory and numerical solution; Surface-charge repulsive effects on the mobility of inorganic colloids in subsurface systems; Colloid transport and the gas-water interface in porous media; Colloid remediation in groundwater by polyelectrolyte; Removal of chromate from aqueous strems by ultrafiltration and precipitation; Potential for bacterial remediation of waste sites containing selenium or lead; Heap leaching as a solvent-extraction technique for remediation of metals-contaminated soils; Factors affecting surfactant performance in groundwater remediation applicationsInfluence of surfactant sorption on capillary pressure-saturation relationships; Surfactant-enchanced solubilization of tetrachloroethylene and degradation products in pump and treat remediation; Solubilization and biodegradation of Hydrophobic organic compounds in soil-aqueous systems with nonionic surfactants; sorption of hydrophobic organic compounds and nonionic surfactants with subsurface materials; Field tests of surfactant flooding: mobility control of dense nonaqueous-phase liquids; Landfill leachate effects on transport of organic substances in aquifer materials; Clay and immiscible organic liquids: greater capillary trapping of the organic phase; Exposure assessmnet modeling for hydrocarbon spills into the subsurface: sensitivity to soil properties.

This book identifies the most important "rules" governing transport, partitioning, retention and transformation of leaked motor fuels in the underground environment. It examines micro-scale fate and transport processes as a means toward promoting a better understanding of larger scale movement of contaminants. Environmental scientists, engineers, consultants, and managers will find Mobility and Degradation of Organic Contaminants in Subsurface Environments to be a useful technical handbook. Less experienced users will appreciate its in-depth explanations of the fate and transport processes vital to effective remedial response. More experienced users will use the book as a source of information, data and equations to support quantitative assessments of pollutant fate and transport.

Research Needs in Subsurface Science provides an overview of the subsurface contamination problems across the DOE complex and shows by examples from the six largest DOE sites (Hanford Site, Idaho Engineering and Environmental Laboratory, Nevada Test Site, Oak Ridge Reservation, Rocky Flats Environmental Technology Site, and Savannah River Site) how advances in scientific and engineering knowledge can improve the effectiveness of the cleanup effort. This report analyzes the current Environmental Management (EM) Science Program portfolio of subsurface research projects to assess the extent to which the program is focused on DOE's contamination problems. This analysis employs an organizing scheme that provides a direct linkage between basic research in the EM Science Program and applied technology development in DOE's Subsurface Contaminants Focus Area. Research Needs in Subsurface Science also reviews related research programs in other DOE offices and other federal agencies (see Chapter 4) to determine the extent to which they are focused on DOE's subsurface contamination problems. On the basis of these analyses, this report singles out the highly significant subsurface contamination knowledge gaps and research needs that the EM Science Program must address if the DOE cleanup program is to succeed.

Across the United States, thousands of hazardous waste sites are contaminated with chemicals that prevent the underlying groundwater from meeting drinking water standards. These include Superfund sites and other facilities that handle and dispose of hazardous waste, active and inactive dry cleaners, and leaking underground storage tanks; many are at federal facilities such as military installations. While many sites have been closed over the past 30 years through cleanup programs run by the U.S. Department of Defense, the U.S. EPA, and other state and federal agencies, the remaining caseload is much more difficult to address because the nature of the contamination and subsurface conditions make it difficult to achieve drinking water standards in the affected groundwater. Alternatives for Managing the Nation's Complex Contaminated Groundwater Sites estimates that at least 126,000 sites across the U.S. still have contaminated groundwater, and their closure is expected to cost at least $110 billion to $127 billion. About 10 percent of these sites are considered "complex," meaning restoration is unlikely to be achieved in the next 50 to 100 years due to technological limitations. At sites where contaminant concentrations have plateaued at levels above cleanup goals despite active efforts, the report recommends evaluating whether the sites should transition to long-term management, where risks would be monitored and harmful exposures prevented, but at reduced costs.