Hazardous materials in the hydrologic environment the role of research by the U.S. Geological Survey

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Hazardous Materials in the Hydrologic Environment: The Role of Research by the U.S. Geological Survey

Committee on U.S. Geological Survey Water Resources Research Water Science and Technology Board Commission on Geosciences, Environment, and Resources

National Academy Press Washington, D.C. 1996

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ii NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the committee responsible for the report were chosen for their special competencies and with regard for appropriate balance. This report has been reviewed by a group other than the authors according to procedures approved by a Report Review Committee consisting of members of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The National Academy of Sciences is a private, nonprofit, self-perpetuating society of distinguished scholars engaged in scientific and engineering research, dedicated to the furtherance of science and technology and to their use for the general welfare. Upon the authority of the charter granted to it by the Congress in 1863, the Academy has a mandate that requires it to advise the federal government on scientific and technical matters. Dr. Bruce Alberts is president of the National Academy of Sciences. The National Academy of Engineering was established in 1964, under the charter of the National Academy of Sciences, as a parallel organization of outstanding engineers. It is autonomous in its administration and in the selection of its members, sharing with the National Academy of Sciences the responsibility for advising the federal government. The National Academy of Engineering also sponsors engineering programs aimed at meeting national needs, encourages education and research, and recognizes the superior achievements of engineers. Dr. Harold Liebowitz is president of the National Academy of Engineering. The Institute of Medicine was established in 1970 by the National Academy of Sciences to secure the services of eminent members of appropriate professions in the examination of policy matters pertaining to the health of the public. The Institute acts under the responsibility given to the National Academy of Sciences by its congressional charter to be an adviser to the federal government and, upon its own initiative, to identify issues of medical care, research, and education. Dr. Kenneth I. Shine is president of the Institute of Medicine. The National Research Council was organized by the National Academy of Sciences in 1916 to associate the broad community of science and technology with the Academy's purposes of furthering knowledge and advising the federal government. Functioning in accordance with general policies determined by the Academy, the Council has become the principal operating agency of both the National Academy of Sciences and the National Academy of Engineering in providing services to the government, the public, and the scientific and engineering communities. The Council is administered jointly by both Academies and the Institute of Medicine. Dr. Bruce Alberts and Dr. Harold Liebowitz are chairman and vice chairman, respectively, of the National Research Council. Support for this project was provided by the U.S. Geological Survey under Grant No. 1434-93A-0982. Copyright 1996 by the National Academy of Sciences . All rights reserved. Copies available from the Water Science and Technology Board, 2101 Constitution Avenue, N.W., Washington, D.C. 20418. Printed in the United States of America

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COMMITTEE ON U.S. GEOLOGICAL SURVEY WATER RESOURCES RESEARCH GEORGE M. HORNBERGER, Chairman, University of Virginia, Charlottesville LISA ALVAREZ-COHEN, University of California, Berkeley KENNETH R. BRADBURY, Wisconsin Geological and Natural History Survey, Madison CONSTANCE HUNT, World Wildlife Fund, Washington, D.C. DAWN S. KABACK, Colorado Center for Environmental Management, Denver DAVID H. MOREAU, North Carolina State University, Raleigh FREDERICK G. POHLAND, University of Pittsburgh, Pittsburgh, Pennsylvania FRANK W. SCHWARTZ, The Ohio State University, Columbus LEONARD SHABMAN, Virginia Polytechnic Institute and State University, Blacksburg MITCHELL J. SMALL, Carnegie Mellon University, Pittsburgh, Pennsylvania ALAN T. STONE, The Johns Hopkins University, Baltimore, Maryland DAVID A. WOOLHISER, Colorado State University, Fort Collins National Research Council Staff STEPHEN D. PARKER, Project Director ANITA A. HALL, Project Assistant

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WATER SCIENCE AND TECHNOLOGY BOARD DAVID L. FREYBERG, Chair, Stanford University, Stanford, California BRUCE E. RITTMANN, Vice Chair, Northwestern University, Evanston, Illinois LINDA M. ABRIOLA, University of Michigan, Ann Arbor PATRICK L. BREZONIK, Water Resources Research Center, St. Paul, Minnesota JOHN BRISCOE, The World Bank, Washington, D.C. WILLIAM M. EICHBAUM, The World Wildlife Fund, Washington, D.C. WILFORD R. GARDNER, University of California, Berkeley THOMAS M. HELLMAN, Bristol-Myers Squibb Company, New York, New York CAROL A. JOHNSTON, University of Minnesota, Duluth WILLIAM M. LEWIS, JR., University of Colorado, Boulder JOHN W. MORRIS, J.W. Morris Ltd., Arlington, Virginia CAROLYN H. OLSEN, Brown and Caldwell, Pleasant Hill, California CHARLES R. O'MELIA, The Johns Hopkins University, Baltimore, Maryland REBECCA T. PARKIN, American Public Health Association, Washington, D.C. IGNACIO RODRIGUEZ-ITURBE, Texas A&M University, College Station FRANK W. SCHWARTZ, Ohio State University, Columbus HENRY J. VAUX, JR., University of California, Riverside Staff STEPHEN D. PARKER, Director SHEILA D. DAVID, Senior Staff Officer CHRIS ELFRING, Senior Staff Officer GARY D. KRAUSS Staff Officer JACQUELINE MACDONALD Senior Staff Officer JEANNE AQUILINO Administrative Associate ETAN GUMERMAN Research Associate ANGELA F. BRUBAKER Research Assistant ANITA A. HALL Administrative Assistant MARY BETH MORRIS Senior Project Assistant ELLEN DEGUZMAN Senior Project Assistant

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COMMISSION ON GEOSCIENCES, ENVIRONMENT, AND RESOURCES M. GORDON WOLMAN, Chair, The Johns Hopkins University, Baltimore, Maryland PATRICK R. ATKINS, Aluminum Company of America, Pittsburgh, Pennsylvania JAMES P. BRUCE, Canadian Climate Program Board, Ottawa, Canada WILLIAM L. FISHER, University of Texas, Austin JERRY F. FRANKLIN, University of Washington, Seattle GEORGE M. HORNBERGER, University of Virginia, Charlottesville DEBRA S. KNOPMAN, Progressive Foundation, Washington, D.C. PERRY L. MCCARTY, Stanford University, Stanford, California JUDITH E. MCDOWELL, Woods Hole Oceanographic Institution, Massachusetts S. GEORGE PHILANDER, Princeton University, Princeton, New Jersey RAYMOND A. PRICE, Queen's University at Kingston, Ontario THOMAS C. SCHELLING, University of Maryland, College Park ELLEN K. SILBERGELD, University of Maryland Medical School, Baltimore STEVEN M. STANLEY, The Johns Hopkins University, Baltimore, Maryland VICTORIA J. TSCHINKEL, Landers and Parsons, Tallahassee, Florida Staff STEPHEN RATTIEN, Executive Director STEPHEN D. PARKER, Associate Executive Director MORGAN GOPNIK, Assistant Executive Director GREGORY SYMMES, Reports Officer JAMES E. MALLORY, Administrative Officer SANDI FITZPATRICK, Administrative Associate SUSAN SHERWIN, Project Assistant

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PREFACE

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Preface

This report is a product of the Committee on USGS Water Resources Research, which provides consensus advice to the Water Resources Division (WRD) of the U.S. Geological Survey (USGS) on scientific, research, and programmatic issues. The committee is one of the groups that works under the auspices of the Water Science and Technology Board (WSTB) of the National Research Council. The committee considers a variety of topics that are important scientifically and programmatically to the USGS and the nation and issues reports when appropriate. This report concerns the WRD science and technology that is relevant to hazardous materials in the soil and water environment, including the subsurface, stream and lake sediments, and surface waters. Within the USGS, this work is dispersed in a number of WRD program areas, including basic research, regional and site assessments, and data collection activities. In the United States, a massive effort is in progress to remediate sites at which hazardous materials threaten the environment. For perspective, it has been estimated that there may be as many as 300,000 sites where soil and/or ground water may require remediation to reverse the negative impacts of past industrial, military, agricultural, and commercial activity. Estimates of the costs of this effort over the next several decades approach a trillion dollars. The science and technology carried out in the WRD, though modest in terms of investment, contributes significantly to the national effort by continually imparting new understanding about the natural processes relevant to the transport, fate, and remediation of hazardous substances in the soil and water environments.

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PREFACE

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This report attempts to help shape the overall framework for the agency's research in hazardous materials science and technology, while pointing up general areas of scientific opportunity, including communications and education. As such, the report does not represent an in-depth review of all germane WRD programs and projects, but instead is a more general document intended to provide strategic advice to WRD management. The committee began its review in late 1993, when most members participated in the regular meeting of the USGS Toxic Substances Hydrology Program in Colorado Springs, Colorado. Subsequently, the committee met five more times before completing this report. At meetings, members were briefed by USGS personnel on a variety of programs and toured field sites—such as the contaminated ground water sites at Otis Air Force Base on Cape Cod, and a site of mining-related metals transport into the Arkansas River in Leadville, Colorado—to acquire information for review. The members wrote individual contributions and deliberated as a group to achieve consensus on the content of this report. It is hoped that by maintaining a broad, forward-looking perspective, this assessment will prove useful. As the committee deliberated and became more cognizant of USGS activities, productive discussions occurred between the members and USGS personnel. This interaction was critical to success of this project. The committee is particularly grateful to Dr. Robert M. Hirsch, Chief Hydrologist, Dr. Gail E. Mallard, Acting Assistant Chief Hydrologist for Research and External Coordination, and their colleagues for all the information and cooperation they provided. It is hoped that this report will help promote the understanding of natural processes relevant to hazardous materials science and technology, and that in turn, this improved understanding will lead to advances in public policy and environmental management. The work of the USGS in this area is key to making progress on one of the most crucial natural resources science policy issues of our time. George M. Hornberger Chair, Committee on USGS Water Resources Research

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CONTENTS

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Contents

EXECUTIVE SUMMARY

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1

INTRODUCTION

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2

OVERVIEW OF THE FEDERAL EFFORT IN HAZARDOUS MATERIAL REGULATION AND REMEDIATION Legislative Background The Evolution of Research in Hydrology Overview of Relevant USGS Programs Comparison of USGS Hydrologic Research to That of Other Organizations From Process Discovery to Application: The Role of the USGS

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8 11 13 17 20

CHARACTERIZATION: PROCESSES AND METHODS FOR IMPROVING UNDERSTANDING The Need State-of-the-art of Characterization Critical Areas of Research Opportunities for the USGS

23 23 24 34 35

REMEDIATION Introduction

37 37

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CONTENTS

State-of-the-Art in the Field Critical Areas for Research Opportunities for the USGS 5

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38 44 45

MATHEMATICAL MODELS AND DECISION SUPPORT Predictive Flow and Transport Models Decision Support Systems Optimization and Decision Analysis Decision Support in the USGS Hazardous Materials Science Program Opportunities for the USGS in Modeling

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CONCLUSIONS Overall Program Framework USGS Collaboration With Other Agencies Some Critical Issues Educational Opportunities Issues in Planning and Implementation

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REFERENCES

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APPENDIXES A

U.S. Geological Survey Water Resources Division Plan for Hazardous Materials Science

B

Biographical Sketches of Committee Members

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EXECUTIVE SUMMARY

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Executive Summary

This report focuses on the programs in science and technology of the U.S. Geological Survey's Water Resources Division (WRD) that are relevant to hazardous materials in soil and water. In the United States, a massive effort is in progress to remediate sites at which hazardous materials threaten the environment. The science and technology programs of the WRD, with a heritage of over 100 years, contribute significantly to the national remediation effort by continually imparting new and credible understanding about soil and water contamination. This report attempts to help shape the overall framework of the agency's research in hazardous materials science and technology, and identifies general areas of scientific opportunity. It is not a detailed critique but instead contains strategic advice to WRD management. The report was developed over a two-year period, during which time information was acquired and assessed and conclusions and recommendations were formulated with respect to: an overall research framework for the agency's pertinent programs, critical areas of research, educational opportunities, methods to evaluate research success, and approaches to improve coordination with others. This report reinforces the widely-held viewpoint that addressing the nation's hazardous materials problems is a large and challenging undertaking involving many entities in a cooperative fashion. Among these entities, the USGS has important roles to play. From a strategic perspective, the agency must affect a shift in emphasis from addressing basic questions in hydrogeological sciences toward solving generic applied problems as congressional attention becomes more oriented toward practical results and as additional methods

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EXECUTIVE SUMMARY

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for solving problems become available. This will require application of a riskbased approach for setting research priorities to assure that resources are directed to activities with the greatest potential benefits to public health and the environment. As part of this risk-based approach, priorities for research and the evaluation of research results must involve input from cooperating agencies and peer review of planning strategies and research results. Although relevant activities in the hazardous materials science and technology program are dispersed throughout the WRD, this study revealed no cause for significant reorganization. Nevertheless, the importance of both internal and external coordination and cooperation will likely increase in the future in response to strong pressure from Congress to increase productivity through interagency cooperation. In many cases this cooperation and proactive outreach will mean maintaining a keen sensitivity to the needs of those entities who are effectively consumers of research and information generated by USGS scientists. The characterization of processes relevant to the transport and fate of hazardous materials in soils and waters is a significant strength of the USGS. Long-term, field-based studies, for example, have been one of the agency's greatest strengths. This type of research should continue and be expanded to integrate methods to evaluate the effectiveness of remediation efforts. Such an approach will require continued dedication to research, together with the development and implementation of new modeling capabilities and decisionsupport tools. The USGS should lead the effort to perform the long-term assessments that are essential to both technology refinement and informed policy decisions.

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INTRODUCTION

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1 Introduction

The U.S. Geological Survey (USGS) has addressed problems related to the contamination of surface waters and ground waters since shortly after its establishment by Congress in 1879. As former USGS hydrologist Walter Langbein recounts (1981), the first USGS paper on the quality of water concerned the use of sewage for irrigation (Rafter, 1897). Studies on the effects of waterborne contaminants have continued to be a focus of the USGS, especially its Water Resources Division (WRD), which was formed in 1949. (The 1949 date is deceptively late. Forerunners of the WRD, the “Irrigation Survey”, the “Hydrologic Branch”, and the “Water Resources Branch” date from before 1900.) During the early part of this century, the majority of the contaminantrelated work by the USGS was done under the auspices of the Federal-State Cooperative Program (Langbein, 1981). This program, in which the federal investment is matched by a cooperator (typically a state), but in which the work is performed by USGS personnel, addresses a variety of problems of local urgency (e.g., sewage discharges, waste storage, urban runoff, etc.). From the mid-1950's to the early 1970's, the research program of the USGS WRD burgeoned (Langbein, 1981). In that era, federal programs within the USGS grew as did the work done for other federal agencies. Subsequent to the 1970s, WRD programs in hazardous materials science and technology have diversified and come into their own as the “bread and butter” of the USGS. The Toxic Substances Hydrology Program was established in 1983, the Nuclear Waste Hydrology Program was established as a separate program in 1985 (although the WRD has had a significant effort in this area since the early

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INTRODUCTION

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1960s), and the National Water Quality Assessment (NAWQA) Program was established as a pilot program in 1986 and as a full-scale program in 1991. Langbein (1981) pointed out the increasingly important niche that was being occupied by studies related to water quality within research programs of the WRD: Over the years there has been a considerable change in the subject matter of research due mainly to corresponding changes in the nation's water problems, especially water quality. Fortunately, the division began to broaden its research in the 1960's with research into water chemistry as such, and soon expanded the scope to include geochemical relations. During the 1950's nuclear bomb testing and the resulting radioactive fallout, and the environmental movement set in motion in the late 1960's both created a vast explosion of interest in water quality, so that it is now the dominant feature of the division's research and includes not only the physical and chemical properties of water, but the biological and ecological as well.

The USGS focus on developing the geoscience knowledge base that is required to address the difficult problems facing the nation regarding the need to maintain good quality waters can be seen as part of a broad effort by many federal, state, and local agencies to come to grips with issues related to the disposal and inadvertent releases of hazardous materials in the natural environment. (In this report, the term “hazardous material” refers to any substance that poses a substantial risk to human health or the environment as a result of contamination of water, air, or soil.) In this sense, several programs of the USGS are related to the science and technology of dealing with hazardous materials in our society. The role of the USGS in the hazardous materials arena lies squarely in the geosciences, the traditional strength of the USGS. The remediation of sites that have already been contaminated is a daunting task. In addition, the development of new sites for disposal of wastes, the determination of allowable discharges into waterways, and the assessment of the efficacy of remediation efforts must proceed with the very best

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INTRODUCTION

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scientific and technical base if the mistakes of the past are to be avoided in the future. The potential roles for the USGS in addressing these serious national problems draw on the experience that the USGS has developed over many decades (Figure 1-1). Recognizing that problems related to hazardous materials research and technology are both national and international in scope, and that the USGS is an agency charged with providing information to resolve important water-related problems of the nation, the Committee on USGS Water Resources Research undertook a review of the research efforts and an assessment of the directions the WRD should take in this area. In support of the USGS's general objective to expand the body of scientific knowledge relevant to hazardous materials and their behavior in the environment, this project sought to: (1) help establish an overall framework for the USGS's research plan; (2) identify critical research areas for the coming decade; (3) advise on educational opportunities in the context of research; (4) provide guidance on processes and measures for evaluating the success of research in this area; and (5) advise on improved approaches for involving “consumers” of the science and technology in program planning and the implementation of results. The committee focused much of its attention on the first two items listed above. With regard to educational opportunities, the general advice to the WRD in Preparing for the Twenty-First Century: A Report to the USGS Water Resource Division (National Research Council, 1991) holds in particular for the hazardous materials programs. With regard to measures for evaluating research, the use of peer review is highly recommended. By involving “consumers” of research in the peer review, the process would also serve to address item 5. Some of these items will be discussed more fully in the final chapter of this report, although the bulk of the technical material in this report will concentrate on a discussion of a framework for research and the identification of some critical areas of research.

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FIGURE 1.1 Potential roles for the USGS in Hazardous Materials Science and Technology.

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INTRODUCTION

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The research conducted by the WRD on topics related to hazardous materials is spread over many complex WRD programs (as described in Appendix A). This report is not a detailed review of work within these diverse programs. Rather, the report is a general review that seeks to provide overall strategic perspective. It concentrates on four main themes: the understanding of natural processes that affect the fate and transport of hazardous substances, the understanding of processes that are useful for remediation of contaminated sites, the use of research results in the decision-making process, and methods to assess the success of the various programs in reaching some of the goals within the critical research areas.

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OVERVIEW OF THE FEDERAL EFFORT IN HAZARDOUS MATERIAL REGULATION AND REMEDIATION

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2 Overview of the Federal Effort in Hazardous Material Regulation and Remediation LEGISLATIVE BACKGROUND Efforts of the federal government to regulate toxic and hazardous materials during the past 40 years have revealed the lack of available knowledge regarding the extent and severity of hazardous material impacts on human health and the environment. It is difficult, for example, to state precisely how many potentially toxic materials are in use, how many enterprises are involved in hazardous waste management, the total volume of chemical wastes generated in the United States each year, and the total number of sites used for hazardous waste management. In addition, very little is known about the toxic effects or environmental fate of many chemicals. Thus, there are abundant research challenges in the area of hazardous materials. The primary role of the USGS in reducing public risks associated with hazardous materials is to provide scientific support, primarily to other agencies. As the nation's leading geoscience agency, the USGS provides analyses of the fate and transport of hazardous substances through natural environments that are crucial to assessing risks and devising remediation strategies. Because the USGS is a public agency, its main responsibility is to perform research that will assist in addressing issues that are most relevant to the public interest: in the case of hazardous materials, those issues that pose the greatest risk to human health and the environment. The federal government first became involved in the regulation of toxic and hazardous substances with the 1958 Food Additives Amendment to the Food, Drug, and Cosmetic Act. This amendment contained the

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OVERVIEW OF THE FEDERAL EFFORT IN HAZARDOUS MATERIAL REGULATION AND REMEDIATION

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“Delaney Clause”, which prohibited the addition of a known carcinogen into human food. In 1972, the federal government began to regulate hazardous materials that are released into the environment with the passage of the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA). This law authorizes the U.S. Environmental Protection Agency (EPA) to register and regulate the sale and distribution of pesticides in the United States. And although FIFRA has limited somewhat the use of pesticides, and thus has produced environmental benefits, it has also resulted in disposal problems, for example, on farms where disposal options are limited. The Toxic Substances Control Act (TSCA), enacted in 1976, was also designed to manage releases of hazardous substances into the environment. TSCA gives EPA the authority to restrict the use of substances that are likely to present an unreasonable risk of injury to human health or to the environment. In the same year, Congress also authorized the first law regulating hazardous wastes—the Resources Conservation and Recovery Act (RCRA). Although this act was passed largely in response to the growing public awareness of serious problems related to disposal, the RCRA actually regulates the generation and transport of hazardous wastes. The Clean Water Act of 1977 as a general pollution statute contains multiple provisions, the most relevant of which pertains to defining EPA's mission in the restoration of the physical, chemical, and biological integrity of the nation's waters. The act prescribes a list of toxic water pollutants and provides that they are subject to effluent limitations based on a “best available technology” standard, with EPA having discretion to impose more stringent limitations based on an “ample margin of safety” standard. This act, of course, has its roots in the 1948 Federal Water Pollution Control Act, the initial federal legislation regarding water quality control, which defined the federal role concerning water quality monitoring and research. Public concern over hazardous substances increased throughout the late 1970s and early 1980s as the Love Canal incident became national news and policymakers began to confront the technical complexities of regulating these substances (Barke, 1988). EPA has estimated that U.S. industries produced approximately 290 million tons of hazardous wastes

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OVERVIEW OF THE FEDERAL EFFORT IN HAZARDOUS MATERIAL REGULATION AND REMEDIATION

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in 1981, and that prior to RCRA, up to 90 percent of hazardous wastes was disposed of improperly (Finley and Farber, 1992). The substantial public concern over hazardous waste disposal sites climaxed with the 1980 enactment of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), commonly known as Superfund, and the 1986 Superfund Reauthorization and Amendment Act (SARA). CERCLA established an information gathering and analysis system to help government agencies characterize and prioritize remediation of hazardous waste sites; it also provided the federal authority to respond to emergencies and remediate sites. The law also created a trust fund to pay for site remediation, and made parties responsible for releases of hazardous substances on lands for which they are liable. SARA requires that priority be given to remediation methods that reduce the toxicity, mobility, and volume of waste rather than trying to contain waste by transferring it to another land disposal facility. As a result of amendments to RCRA and CERCLA, there has been a move away from land disposal of hazardous wastes. In the mid to late 1980s, following the end of the cold war, the nation began to recognize the extent of radioactive and other hazardous wastes stockpiled at Department of Defense (DOD) and Department of Energy (DOE) facilities. Potential threats to human health and the environment near these sites come not only from the millions of gallons of wastes that are currently awaiting proper disposal, but also from seriously contaminated soil, ground water and surface water, and from releases to the air. Estimated costs for remediation of these sites exceed $100 billion (World Resources Institute, 1993). The U.S. Environmental Protection Agency began to question the high priority placed on remediation of hazardous waste sites in the late 1980s, as the agency broadened its use of scientific risk assessment. In February 1987, the EPA released a report on the relative risk of environmental problems in an attempt to set priorities for its own activities (U.S. Environmental Protection Agency, 1987). The report concluded that areas related to ground water consistently ranked medium or low in terms of the relative risk they pose to human health and the environment. The report found that active hazardous waste sites ranked relatively high in cancer risks but relatively low in noncancer human health risks and ecological effects. These sites can also depress property

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values. Overall, they were ranked medium in terms of risks to welfare. The report further concluded that RCRA sites, Superfund sites, underground storage tanks, and municipal non-hazardous waste sites were among areas of high EPA effort but relatively medium or low risk (Environmental Protection Agency, 1990). Methods for evaluating risks posed by environmental contamination also began to change significantly in the late 1980s. Conclusions about the relative risks to human health and the environment historically have been derived from in vitro tests of toxic pollutants for acute problems such as skin rashes, eye sensitivity, and immediate mortality to test species such as fish or algae. Cancer risk also has been evaluated for many chemicals based on laboratory tests. Within the last decade, however, scientists have been accumulating more information regarding chronic effects of toxic pollutants largely from field studies of wildlife and accidental exposures of humans to organohalogens such as polychlorinated biphenyls, or PCBs (see for example, Colburn et al., 1990). These studies indicate a correlation between toxic pollutants, particularly persistent, bioaccumulative, organohalogen compounds, and teratogenic effects in humans and wildlife. More recent research has discovered that a number of synthetic chemicals, including pesticides, components in plastics and detergents, and other industrial products and by-products, are capable of disrupting the endocrine system. Humans and other organisms are exposed to these substances primarily through air, water, and ingestion. These findings, like much of scientific research, tend to raise more questions than they answer. A substantial amount of public funds is expended on hazardous material research, regulation, and remediation. In an area of environmental management where so much uncertainty continues to exist, it is difficult, but vitally important, to set priorities for research that will be of most benefit to the public interest over the long term by assuring that remedial actions are based on sound science and that regulations are formulated and enforced in an informed manner. THE EVOLUTION OF RESEARCH IN HYDROLOGY The National Research Council recently described a conceptual model of the evolutionary stages of research in hydrogeology (National Research Council, 1992). Taking a process-oriented viewpoint, the report illus

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trates how research follows a well-defined pathway that leads from process discovery to process description and finally to process application. Process discovery is concerned with the original characterization of a process and often its mathematical formulation. Such a discovery may derive from experiments, field studies, or theoretical analyses. In most instances, contributions are required from all areas. A case in point is the study of dispersion in porous media. The original studies on the process of dispersion occurred in the early 1950's with simple column experiments and the development of the theoretical-mathematical description of the component processes. The role of dispersion at field scales remained poorly understood until the late 1970's when appropriate theoretical studies combined with subsequent large-scale field experiments were advanced. Thus, process discovery depends upon a complementary collection of research techniques involving laboratory, field, and theoretical approaches. After a process is discovered, the thrust of research shifts to process description. This research expands the knowledge base about processes, detailing how the process works, determining its relative importance to other processes, and establishing values for characteristic parameters of the process. The main investigative approaches involve carefully controlled field and laboratory experiments, and sensitivity analyses with mathematical models. Returning again to the study of dispersion, examples of research on process discovery include the many laboratory experi-experiments designed to establish “characteristic” values of dispersion lengths for different types of media, and field studies to quantify correlation structures that give rise to macro-scale dispersion. After a process and its controlling parameters are well understood, it is possible to utilize this knowledge to solve practical problems through process application. For example, after discovering the ability of indigenous populations of microbes to biodegrade some organic contaminants, and describing the conditions under which these processes occur, it is possible to focus on the development of related remedial methodologies. The conceptual model described above portrays how research in processoriented hydrology should proceed, and serves as a basis for this report. The remainder of this report examines the state-of-the-art of research in areas related to hazardous materials science and technology, explains how the USGS is presently positioned for this research, and

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explains how the USGS is presently positioned for this research, and describes opportunities for the USGS in addressing critical needs in these areas. The character of scientific research has changed with time. For instance, from relatively humble beginnings in the 1920's, 1930's, and 1940's, hydrology has developed into a complex science embodying elements of physics, chemistry, mathematics, and biology. The research categorization methodology developed in the previous section can be used as a measure of research progress in the study of flow and mass transport processes. In general, as fundamental problems are solved and experience is gained, the research emphasis logically shifts to applications. For example, such is the case with ground water flow through saturated media. After over 100 years of research, the continuing focus in the area of saturated flow is mainly to develop flow codes (e.g., MODFLOW; McDonald and Harbaugh, 1988), or computational enhancements to codes (e.g., Hill, 1990). The study of coupled flow processes (complex problems where, for example, mass transport depends upon fluid flow and fluid flow depends upon mass transport), however, remains at the process discovery stage and will require extensive research to sort out a large array of complex effects. The emphasis on research related to problems of hazardous waste will almost certainly shift toward applications. What remains to be discussed is what ultimately brings about this shift to applications, and when it is likely to occur in the various process areas. Analysis of these questions should be useful in planning future USGS research efforts on hazardous materials science and technology. OVERVIEW OF RELEVANT USGS PROGRAMS The WRD of the USGS has a number of programs in which studies are conducted to aid in resolving problems related to the contamination of surface and ground waters by hazardous materials (see Appendix A). Funding for projects related to hazardous materials in various programs within the USGS has reflected priorities established both by the USGS and by Congress (Figure 2.1).

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FIGURE 2.1 Expenditures on USGS programs related to hazardous materials: Federal-State Cooperative Program, Toxic Substances Hydrology Program, Low-Level Nuclear Waste Hydrology Program, Department of Defense Environmental Contamination Program. Note: The values for the Federal-State Cooperative Program are estimated by assuming that approximately 14 percent of the total Federal-State budget, the future reported by Gilbert et al. (1987) for FY 1986, is devoted to contaminant-related work.

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Funding for the Federal-State Cooperative Program for projects on hazardous materials has increased fairly substantially, although in terms of constant dollars, the funding for the program has been essentially flat. Funding for the Toxic Substances Program, by the same reasoning, has decreased slightly in constant dollars. Funding for the Nuclear Waste Hydrology Program declined to zero in 1994. In addition to programs funded internally by the USGS, other federal agencies also fund work related to hazardous materials that is performed by USGS personnel. In recent years, work in support of environmental restoration and waste management at Department of Defense (DOD) sites has increased drammatically. Over the past eight years, the relative contribution of the various major programs has shifted somewhat, with an increase in the percent of the work funded other federal agencies being related to growth in work related to hazardous materials (Figure 2.2). Within and across USGS programs related to hazardous materials science and technology, there is a spectrum of activities that ranges from pure research to what may be called service—the problem-solving function of the Water Resources Division within government. Separating research from service is not an easy task. Langbein (1981) addressed this question by starting with Webster's definition of research “(1) careful or diligent search (2) studious inquiry or examination esp....having for its aim the discovery of new facts and their correct interpretation, the revision of accepted conclusions, theories or laws, ...or the practical application of such new or revised conclusions, theories, or laws.” He pointed out that with a definition as broad as (1), virtually every program of the USGS, including data collection, would constitute “research”. He preferred instead the more narrow definition implied in (2), which he interpreted to mean new techniques, instruments, and exploration (Langbein, 1981). By this latter definition, research constitutes a relatively small proportion of the activities of the Water Resources Division. Activities related to hazardous materials science and technology that concentrate almost exclusively on research are found mainly in the Toxic Substances Hydrology Program, which involves researchers in USGS district offices and the national centers. In addition, core funding for the National Research Program (NRP) contributes significantly to the overall research effort in hazardous materials science and technology. There are also

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FIGURE 2.2 Breakdown of funding by major source of funds: Federal appropriations, state and local government contributions to lthe Federal-State Cooperative Program, and reimbursements from Other Federal Agencies. Source: Data for FY 1986 from Gilbert et al. (1987). Data for FY 1994 from material provided by G. Mallard, USGS, Reston, VA.

many projects under the Federal-State Cooperative Program that have a substantial research component. NAWQA, which has a small research component, also provides opportunities for integration of research from other USGS programs within the framework of issues of national concern. In this study, the research and service activities of the USGS have been differentiated in order to concentrate primarily on research. It is recognized that the service functions can and do contribute to research, but a more intensive focus on the issue of research per se was chosen.

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COMPARISON OF USGS HYDROLOGIC RESEARCH TO THAT OF OTHER ORGANIZATIONS Hazardous material and toxic waste research in the United States is conducted by a variety of organizations including universities, federal and state government agencies, and large and small corporations. Historically, the type of research each has conducted has been framed by a variety of factors, such as the mission of the organization, history, and circumstance. Federal agencies with missions related to regulating hazardous materials (e.g., EPA) or with extensive remediation problems at agency sites (e.g., DOD, DOE) have a perspective toward research strongly oriented toward short-term results. The USGS is one of the few federal agencies with a more long-term view, having a broad program in field-oriented, multidisciplinary research in hazardous materials science as related to problems in the natural environment. The USGS is known throughout the world for its experience in monitoring the natural environment and for the collection of high-quality, consistent data sets. The USGS is particularly well versed in taking an integrated approach to the study of systems and for including the important details regarding temporal and spatial variability in characterizing natural constituents. Universities, by virtue of the discontinuous funding they receive for research and the relatively more limited infrastructure, typically restrict their research to aspects of process discovery. Much of the work involves computer simulation or laboratory experimentation. Field-related hazardous material remediation studies, when they are undertaken, often require strong support from organizations like the USGS, ARS, or the DOE that have ongoing field operations. Some programs have been able to fund field research at high levels from a variety of funding sources, but this is the exception rather than the rule. Programs of the USGS related to hazardous materials science and technology are dominated by field studies that have as their goal the discovery and description of surface and ground water flow and mass transport processes. This focus is understandable, given the historical roots of research within the Water Resources Division, and the distributed character of the organization where many researchers work in district offices. The USGS is one of a very few organizations among all of the

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groups (universities, other federal agencies, and states) that has the ability to conduct long-term research in field settings. EPA, DOD, and DOE focus much of their research efforts on applications owing to their cleanup responsibilities. These agencies have large and active programs concerned with developing new remedial strategies for the cleanup of hazardous and mixed wastes. Much of this research has a strong engineering orientation directly related to waste (ex situ and in situ waste treatment). All three agencies support fundamental process studies through their large extramural grant programs and their own laboratories. Research and development work in industry is mainly concerned with the commercialization of new remedial processes and the development of new measurement processes. The research and development work being performed is tied closely to practice. Interestingly, the focus of research also can be influenced by the nature of the reward system. For example, excellence in research at the discovery end of the spectrum often is “measured” by papers published in high quality scientific journals that stress innovation in research. Relatively little attention is paid to whether the research is “industrially relevant”. At the applications end of the spectrum, success is measured by patents, licenses, and commercialization. In many cases, research is presented in the scientific literature for reasons other than to advance science. This discussion raises important questions concerning the future direction of research related to hazardous materials. For example, are there reasons why the USGS or any of the other organizations should reallocate their activities differently across the research sub-divisions—discovery, description and application? Are there factors that would favor one given research topic over another? Clearly, the assessment of what research will be most important in the next decade depends upon the selection of rational criteria that might serve to identify critical research. To a large extent, the “consumer” of the research determines the prioritization of research foci or areas. Some organizations, like the National Science Foundation, are responsive to national and international needs and initiate research in critical areas such as “Global Change and Continental Hydrology” and “Math and Science Education”. Another large body of research consumers is represented by industrial hydrogeologists. To this group, critical research is that with the

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potential to affect the practice of hydrogeology. It is more difficult to support research programs in the area of process discovery and term them as critical. However, programs such as the “solvents in ground water program” at the University of Waterloo, and the “microbial processes program” and the “passive bioremediation program” developed within the USGS under the leadership of Derek Lovely and Mary Jo Baedecker, respectively, are examples of successful research. Another, slightly different consumer of critical research is the organization that is conducting the research. For example, critical research for AT&T or IBM is that research that has the potential to develop new products within the organization. Critical research at the USGS might involve research that creates opportunities for technological leadership or increases the effectiveness of its district efforts. Critical research also may advance specific goals or missions of the agency, or the public and political perception of what the agency mission is all about. To date, individual researchers within the hazardous waste programs bear the major responsibility for determining the direction and focus of future studies. In many respects, such an approach provides the academic freedom of a university researcher with the added benefit of at least some assured funding. This emphasis on curiosity-driven research has served both the USGS and individuals well in the past. It could be argued that political and economic realities have eclipsed this research model, however. The major corporations cited above all have restructured their research programs in fundamental ways that emphasize corporate needs for research and development. For example, although some may lament the passing of the “old” Bell Laboratories as the premier basic research organization of its kind in the world, AT&T has adapted to the realities of the market place. The Toxic Substances Hydrology Program has developed and flourished as a curiosity-driven research program that has capitalized on the particular abilities of the USGS to conduct large-scale interdisciplinary field studies. Nevertheless, there are important ways in which the Toxic Substances Program must evolve to ensure that the work of the USGS is focused on work of highest importance to the nation. First, more of the work must be made immediately relevant to the major cleanup issues that the country is presently facing at industrial and defense facilities. The report's recommendations in the areas of remedial technologies provide

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an overview of how to address this problem. Second, complementary laboratory and modeling studies must be used to support and to generalize field investigations, which have been the focus of much of the work to date. FROM PROCESS DISCOVERY TO APPLICATION: THE ROLE OF THE USGS As pointed out above, the research programs of the USGS related to hazardous materials are focused on studies of surface and ground water flow and mass transport processes. The endpoints for this research—the applications —are: 1) the analysis of water resources and of sites as to their suitability for waste disposal; 2) the analysis of contaminated resources and sites to evaluate the need for cleanup and to determine effective strategies for cleanup; and 3) the provision of unbiased information to guide legislation and governmental policy decisions. These are topics of critical concern to the nation. Conservative estimates of the cost of cleaning up contaminated sites in the United States are very large. Considering only ground water and soil remediation, and considering only DOE sites, estimated costs over the next three decades are several hundreds of billions of dollars (National Research Council, 1994c). When surface waters, wetlands, and sediments are included and attention is not focused solely on DOE, it is clear that solutions to the problems associated with hazardous materials in the environment are both costly and daunting. Potentially toxic chemicals are now present, at least in trace quantities, essentially everywhere. For example, polychlorinated biphenyls (PCBs), DDT, dioxins, hexachlorocyclohexane (HCH), dibenzofurans, chlordane, and toxaphene have been found in arctic air, surface water, snow, suspended sediments, fish, marine mammals, seabirds, terrestrial animals and humans (Barrie et al., 1992; Lockhart et al., 1992; Muir et al., 1992; O'Connor et al., 1992; Thomas et al., 1992). The nearly ubiquitous nature of hazardous materials presents two key challenges to those involved in research on hazardous materials in the environment: defining the major problems (with regard to risk to human health and

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ecosystem functioning) and determining practical alternatives for alleviating the problems. A broad range of problems involving the contamination of water resources affect the United States. Surface waters, including streams, rivers, wetlands, lakes, reservoirs, and estuaries, are contaminated with organics, metals, nutrients, and sediments. Sources of the contamination range from industrial discharges to agricultural runoff to direct deposition from the atmosphere. Because many of the contaminants that are released into surface waters partition onto sediments, there are also significant problems associated with hazardous materials in deposits of sediments in waterways and wetland areas. A recent NRC report (National Research Council, 1990a) summarizes some of the problems related to contamination of surface waters and sediments, and provides recommendations for restoration of these aquatic systems. Ironically, laws passed between 1952 and 1977 to control air and water pollution caused many industries and municipalities to turn to land disposal for wastes, an action that has contributed to some of the most difficult problems of ground water and soil contamination now faced. Estimates of the number of contaminated sites in the United States range in the hundreds of thousands, with a variety of contaminants present in the soils and ground waters. Some of the issues related to hazardous substances in ground water are addressed in a recent NRC report (National Research Council, 1994a). The long-term outlook for environmental cleanup at contaminated sites is not clear. Nor are all of the requisite tools available to determine in a costeffective manner when natural processes will suffice, i.e., when “passive” or “intrinsic” remediation will be adequate to protect humans and ecosystems in the final analysis. Moreover, the scientific understanding and methods needed to assess the appropriateness of a given site as a waste-disposal facility are not all yet available. The strength of the USGS has been in areas of geoscience: in collecting data that allow assessment of the quality of water, in gaining a fundamental understanding of what natural processes are important in the transport of contaminants (including biogeochemical reactions), and in developing models that are useful in analyzing contaminant transport in natural systems. Building on these strengths, the USGS should pursue a strategy in the area of hazardous materials science and technology that

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stresses: 1) improvements in the ability to characterize natural environments in terms of the transport of contaminants and of the biogeochemical reactions that affect these contaminants (i.e., gaining an understanding of the nature of different environments, including processes that affect contaminants); 2) improvements in methods for remediating contaminated sites (i.e., gaining an understanding of the processes and techniques that are useful for containing and for cleaning up contaminated sites); and 3) improvements in the way information gained from scientific studies can be used to reach decisions about appropriate actions in cases where cleanup is likely to be difficult and costly. It is in these areas that the USGS can make important contributions toward solving the problems associated with remediation of contaminated sites and with protection of the environment, especially with regard to proposed new waste-disposal sites. Some of these issues are explored in the remainder of this report.

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3 Characterization: Processes and Methods for Improving Understanding

THE NEED Contamination of the environment (surface and subsurface; waters, soils, sediments, and biota) with hazardous materials has occurred through a variety of mechanisms induced by humans. Sources of contamination are classified as either point (a single, concentrated, identifiable source) or nonpoint (a diffuse source). For example, a chemical spill is a point source of contamination, whereas runoff from fertilized farmland is a nonpoint source of contamination. Since the industrial revolution, human activities have served to introduce both anthropogenic and natural materials to the environment in unnatural ways. For example, certain mining operations have produced widespread contamination of surface waters and stream sediments with elevated levels of metals. A broad spectrum of contaminants have been introduced to the environment in a variety of ways, including surface spills, underground pipeline leaks, surface seepage basins, direct releases to streams or lakes, and underground injection wells. Many industrial operations have resulted in subsurface contamination by solvents. Many facilities that handled petroleum hydrocarbons (tank farms, refineries, pipelines, and gasoline stations) have contaminated the subsurface. Organic contaminants such as solvents and petroleum hydrocarbons have migrated rapidly in the subsurface at these sites, often creating large ground water plumes. Naturally-occurring toxic substances that present human health concerns also have been identified in ground water and surface water. In a number of cases, radioactive materials and trace metals from natural sources have

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been found in ground water at levels that exceed public health drinking water standards. For example, LeGrand (1988) reported elevated activities of radium and radon in ground waters of the Piedmont Plateau and the Blue Ridge Mountains. Other toxic substances known to occur naturally at levels exceeding drinking water standards include arsenic, fluoride, lead, strontium, and selenium (Hem, 1992). The USGS maintains and distributes a data base containing chemical analyses of ground water and surface water for many areas of the United States (Hoffman and Buttleman, 1994). STATE-OF-THE-ART OF CHARACTERIZATION The characterization of sites containing hazardous materials must involve an interdisciplinary approach with personnel with expertise in the fields of hydrology, geology, geochemistry (contaminant distribution), analytical chemistry, microbiology, ecology, statistics, and image processing. Improved understanding of the processes involved in, or affecting, contaminant transport is critical to developing innovative approaches to characterizing both the surface and the subsurface, and ultimately preventing future contamination or remediating sites already contaminated. According to a previous NRC report “the greatest progress will be made if site cleanups are accompanied by investigations aimed at identifying the critical conditions and processes controlling contaminant behavior...” (National Research Council, 1994b). Improvements in process understanding and the development of innovative tools for characterization are needed to advance the state of knowledge of contaminated sites. In situ remediation represents an attempt to change the physical, chemical, and biological attributes of natural systems to mitigate the adverse effects of hazardous materials in the environment. In order for in situ remediation to be successful, the link between particular attributes of natural systems and the processes affecting the hazardous constituents must be established clearly.

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Constituents The physical, chemical, and biological attributes of natural systems vary from site to site. Characterizing these properties is important because they determine the response of natural systems to contamination by hazardous materials. The geology and hydrology define the transport characteristics of the system. Dissolved anions and cations, mineral surfaces, and natural organic matter all represent chemical “reagents” that react in distinctive ways with hazardous waste chemicals. In addition, distribution of bacteria, plants, and other organisms and their level of metabolic activity are affected by the amount of organic carbon sources and the nature and amounts of electron acceptors available. In recent years significant advances have been made in the characterization of the chemical and biological constituents of natural systems and in the understanding of how they react with hazardous materials. The composition, physical structure, and chemical properties of oxides, clays, and other products of rock weathering have been extensively characterized (Banfield et al., 1991), and have been examined within the context of prevailing hydrologic and biogeochemical conditions (Hem and Lind, 1994; Webster and Jones, 1994). Information of this kind is important for establishing the types of mineral surfaces present in soils and aquifer sediments capable of sorbing pollutant ions (Balistrieri and Chao, 1990; Fuller et al., 1993). For example, iron (II) as a component of silicate and other minerals commonly found in most aquifer materials, has been demonstrated as a strong reducing agent with the capacity to remove many contaminants from the ground water (White, 1990). The efficacy of the iron (II) reduction process has been demonstrated on chromium (VI) in the laboratory (Anderson et al., 1994), and several field-based researchers are examining the efficacy of solids containing both elemental iron and iron (II) as a reactive barrier to remove organic solvents from ground water (Wilson, 1995). Natural organic matter is an exceedingly complex material that significantly affects fate and transport of pollutants in the environment. Methods have been developed to divide organic matter samples into distinct molecular size and chemical property fractions (Aiken et al., 1992). Chemical derivatization and spectroscopic methods have been used to substantially improve understanding of functional groups and

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other structures within natural organic matter (Leenheer et al., 1995). Further research is needed to evaluate sorption of organic pollutants onto soils (Chiou et al., 1983) and to evaluate the role of organic matter in oxidation/reduction reactions, precipitation/dissolution reactions, and complex formation reactions with naturally-occurring and contaminant-derived metals (McKnight and Bencala, 1990). Bacteria, plants, fungi, and other biological species play an important role in the transformation of both naturally-occurring and contaminant chemicals within the environment. Documenting the distribution and metabolic activity of microorganisms, particularly in subsurface environments, is important for evaluating the potential for biodegradation of contaminants (Vroblesky and Chapelle, 1994; Chapelle et al., 1995). Much has been learned in recent years about the types and abilities of microbial populations indigenous to the subsurface (Thiem et al., 1994). The reduction of selenium (Oremland et al., 1994) and uranium (Lovley and Phillips, 1992) by bacteria has been established recently, providing good evidence that microorganisms play a greater role in the redox transformations of inorganic contaminants than was previously suspected. As additional synthetic organic compounds are shown to biodegrade (Visscher et al., 1994), and as biodegradation in field settings is better understood (Cozzarelli et al., 1994), the need to properly assess the potential for biodegradation becomes more readily apparent. Indeed, a remediation strategy involving no additional active measures is being considered for some contaminated sites where the processes of natural attenuation and biodegradation are acting to remediate the site. This new approach to cleanup of hazardous waste sites is highly dependent on a good characterization of the environment and a sufficient understanding of these processes. Processes It is important to understand the processes governing natural systems on several temporal and spatial scales. Pertinent temporal scales are linked to a number of factors: the rates of chemical and biological process, the transport of solutes and sediments in the hydrologic cycle, the ecosystem response, and possible human disturbance. Pertinent

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spatial scales range from the molecular (where fundamental chemical and biological processes take place) through intermediate scales that govern flow through porous media and the distribution of microorganisms and invertebrates, to scales applicable to human activities and whole ecosystems, to the global scale. Processes such as precipitation/dissolution, adsorption, complexation, and dispersion, and factors such as oxidation/reduction and pH, control the migration of many constituents in the environment. A better understanding of these processes and controls with a focus on hazardous constituents, will enhance the ability to characterize sites with known contamination and to design effective remediation systems. Prior environmental research has focused primarily on processes occurring in a single medium: air, soil, or water. Natural environments are open systems, however, and processes acting across media are of fundamental importance. In order to understand the dynamic behavior of natural systems, an interdisciplinary approach is required. Subsurface Processes Significant advances in knowledge of subsurface contaminant migration processes have occurred in the last thirty years. Improvements in understanding of processes such as facilitated transport, adsorption, and dispersion have enhanced contaminant distribution prediction and remediation systems design. Progress also has been made in understanding the geological processes that formed most subsurface units. In particular, more has been learned about depositional models, diagenetic processes that alter geologic materials, subsurface heterogeneities, and the hydrology of ground waters that flow through complex subsurface matrices. Additional advances are needed to achieve a better understanding of the heterogeneous nature of the subsurface, however. Significant progress has been made in the last 20 years in understanding the ecology of subsurface microorganisms and the role they play in the fate and mobility of contaminants. Microorganisms have been shown to transform hazardous materials to products that are either harmless or less hazardous, to convert them to forms with differing solubility, or to sorb them onto cell surfaces. In addition, notable advances have been

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made in knowledge of the degradability of numerous hazardous compounds, including the identification of specific degradation pathways. Many questions with respect to biological processes in the subsurface, such as microbial transport (Hurst, 1991), and the fate and degradability of contaminants, still remain unanswered, however. Because contaminants such as gasoline and solvents have entered the subsurface as separate phases (i.e., not as a dissolved phase in water) it is also necessary to understand multiphase flow in the subsurface. Most research in this area has concentrated on model studies and well-controlled laboratory investigations. This theoretical work, originally developed within the petroleum industry, provides an important theoretical and methodological framework for subsequent work that has occurred in the field of hydrogeology. The problems are even more complex in the field of contaminant transport because they involve interphase mass transfers. Compositional models that incorporate interphase transfer (Abriola and Pinder, 1985a,b; Baehr and Corapciouglu, 1987) have been used as the principal approach to modeling nonaqueous phase liquid (NAPL) flow. True multiphase capabilities incorporating complex patterns of gas flow and mass removal have been developed to support theoretical investigation of remedial approaches such as gas sparging or soil venting. Mass transfer between NAPLs and water and between aqueous and gas phases is being studied to improve the knowledge of contaminant migration through the subsurface (Anderson et al, 1992; Miller et al., 1990; Whelan et al., 1994). There is a deficiency of fundamental field and laboratory data concerning multiphase flow parameters relevant to contaminant systems. Physical models have been utilized to improve the state of understanding. Mass transfer reactions typically encompass families of nuclear, chemical, and biological processes. Although some of these processes like radioactive decay are well understood, those processes involving multiple chemical species and biological reactions are much less understood and provide a major focal point of contemporary research in contaminant hydrogeology. Valid conceptual and mathematical representations exist for many of these processes, but they have not yet been applied to solving real world problems. For example, the use of overly simplistic models such as distribution coefficients to describe sorption is now being re-evaluated in terms of better conceptual and mathematical models (Barber,

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1994; Harvey et al., 1989; Harvey and Garabedian, 1991; Stollenwerk, 1991). Other important areas of research include the modeling of complex species in solution (MINTEQ: Felmy et al, 1983; EQ3/EQ6: Wolery, 1979) and the incorporation of inorganic reactions into flow and mass transport models (Cederberg, 1985; Liu and Narasimhan, 1989; Narasimhan et al., 1986). The diversity and complexity of subsurface systems require an understanding of coupled flow processes. Coupling of thermal, hydrologic, mechanical, biological, and chemical processes is required to obtain a complete understanding of the subsurface. Tsang (1987) provided a general overview of the commonly studied coupled problems in hydrology. The most advanced studies to date involve codes such as V-TOUGH, developed for the Yucca Mountain nuclear waste repository program to predict the response of the hydrologic system to significant repository heating (Buscheck and Nitao, 1992). Other studies have examined density-driven transport of dense hydrocarbon vapors in partially saturated media (Mendoza and Frind, 1990a,b) and the development of instabilities in variable density flow (Schincariol and Schwartz, 1993). The study of fractured media has been a major focus of a group of researchers over the last 30 years. New knowledge about how fluids move in the subsurface through fractured media has been obtained through advancements in fracture flow modeling and field experiments. For example, the USGS has recently conducted in-depth, multidisciplinary studies of site characterization and ground water movement in fractured rocks at the Mirror Lake site in New Hampshire (Hsieh et al., 1993). These studies have brought together hydrogeologists, geophysicists, geochemists, structural geologists, and numerical modelers to address fundamental questions of fluid flow in such environments. Theoretical work in this field has continued to progress through the development of more realistic fracture flow codes. The state-of-the-art in discrete fracture models is represented by codes such as NAPSAC (UK Harwell) and FracMan/MAFIC (Golder Associates, 1988). Recent work (Sudicky and McLaren, 1992) has extended the discrete modeling approach to accommodate complex fracture matrix coupling in both flow and contaminant transport. Most field and laboratory studies related to fractured rock problems continue to be motivated by the need to assess the implication of fracturing in relation to waste storage and contaminant transport.

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Surface Processes When potentially hazardous materials are accidentally spilled or are deliberately applied on vegetation or soils, they may be transported to surface waters by direct surface runoff, or to aquifers by water percolating through the unsaturated zone. Surface waters deserve a great deal of attention because of their widespread use as drinking water sources, their importance to fisheries and as habitats for wildlife, and their role in the hydrologic cycle. Energy production, manufacturing, agricultural production, mining, and waste treatment all are performed in close proximity to surface waters, and all represent potential sources of contamination. In addition, surface waters receive both ground water and atmospheric inputs of contaminants. Sediments, which often contain considerable contaminant levels as a result of past activities, are both contaminant sources and sinks with respect to the water column. Intensive field and analytical research on the fate and transport of surface applied chemicals has been carried out since the mid-1960s. Much of this research has been done by the Agricultural Research Service (ARS) of the U.S. Department of Agriculture (USDA) and by universities. These groups have developed several computer models that predict the fate and transport of agricultural chemicals in order to assist policy-makers in making regulatory and policy decisions (U.S. Department of Agriculture, 1980; Smith, 1992). However, there are many uncertainties involved in predicting the fate and transport of surface applied chemicals because of the complicated nature of the processes and the unpredictability of factors such as precipitation (Woolhiser, 1976). The flow and chemical composition of upland streams and rivers are strongly linked to hydrologic processes and biogeochemical processes within the watershed. There is a clear need to evaluate the causative factors in temporal variability, especially as they pertain to the movement of hazardous materials. McKnight and Bencala (1990) and McKnight et al. (1992) of the USGS have made significant progress in understanding the temporal behavior of iron, aluminum, and natural organic matter in streams and rivers, and their biogeochemical linkages. In these studies, the exchange of water and solutes with adjoining sediments and aquifers has been found to be significant.

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Lowland rivers, lakes, and estuaries are linked to larger and more complex watersheds. Establishment of sources and sinks to such systems is essential, as is the development of a hydrologic model that can account for mass transport. The dynamic behavior of pesticides and other organic contaminants in San Francisco Bay has been found to be a strong function of the distribution between water and suspended sediment (Domagalski and Kuivila, 1993). Distinguishing hydrologic inputs from atmospheric inputs is important for evaluating the efficacy of existing regulatory controls on contaminant release. Estimates of atmospheric inputs into the Chesapeake Bay, for example, have been revised upward in recent years (Baker et al., 1994). When dealing with sites contaminated at the ground surface, ecological characterization is essential. Improving the understanding of stresses and changes that have occurred as a result of contamination at a site is critical to the long-term goal of site restoration. Ecological processes must be understood so that contaminant migration and processes of natural attenuation can be better understood. Characterization Methods Characterization methods available to the geosciences community have improved vastly in recent years. Some new methods represent cost-effective and reliable alternatives to existing characterization methods, whereas others provide insight into parameters and processes that was not available in the past. In order to obtain information about the geology of a site, samples are generally collected by drilling holes into the subsurface. Indirect information about the subsurface geology also can be obtained using both surface and downhole geophysical tools. Existing methods for characterizing the hydrology of a site include the installation of wells and piezometers from which aquifer tests and tracer tests can be performed. In order to obtain information about the geochemistry of a site (contaminant distribution), samples are collected from soils (both at the surface and downhole), from ground water, and from vapor samples in the unsaturated zone.

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Innovations in characterization technology have been developed to promote collection of better data at lower cost. Emphasis has been placed on innovative drilling technologies that minimize the amount of hazardous waste extracted while maintaining the integrity of samples collected. New techniques to perform chemical analyses in the field have been developed to lower overall analytical costs and allow for real-time data collection. Innovative geophysical tools have been developed recently to enable collection of better data about the geology, geochemistry, and hydrology of the subsurface, while also minimizing the amount of intrusion into contaminated zones and reducing costs. Chemical isotopes have been utilized to characterize the age of ground waters and to trace or delineate ground water flow paths. All this information is used to improve the understanding of the migration of contaminants with the ultimate goal of promoting better design of remediation systems. Innovative drilling technologies recently applied to hazardous waste site applications include the cone penetrometer, which collects geologic and geochemical data before new drilling locations are selected. These data are used to design a more standard drilling program for characterization of the site and for installation of monitoring wells. Other innovative drilling technologies include sonic drilling, which minimizes hazardous waste materials extracted during drilling while maintaining the quality of the core that can be obtained from the subsurface (Barrow, 1994). Horizontal drilling has been modified for drilling at hazardous waste sites, enhancing access to the subsurface and promoting characterization and remediation of sites otherwise inaccessible, such as under large buildings or under landfills (Kaback et al., 1989). Innovative sampling technologies include the SEAMIST™ liner that collects vapor samples at discrete depths in the unsaturated zone. The HydroPunch™ and the BAT™ sampler have been used to collect depth-discrete ground water samples from a single borehole (Kaback et al., 1990). Fiber optic sensors have been developed to detect subsurface contamination in monitoring wells and have been adapted to the cone penetrometer to provide real-time data in the field (Colston et al., 1992). Innovations in three-dimensional image analysis have allowed scientists to create better visualizations of subsurface contamination (Eddy and Looney, 1993). Geophysical methods for imaging the subsurface also have been improved. For example, crosshole tomography using electrical

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resistivity, electromagnetics, and seismic sources has been demonstrated as a tool to image subsurface geology, hydrology, and the effects of in situ remediation on the subsurface. Fate and transport modeling has been advanced using new codes developed to mimic real subsurface conditions, such as heterogeneity, fractured bedrock, and adsorption. The understanding of subsurface microorganisms, their diversity, and their innate ability to remediate contaminants in the subsurface has developed recently into an important research area. Innovative techniques to characterize these intrinsic inhabitants of the subsurface using DNA probes are an example of recent advances in the state-of-the-art (Hazen and Jimenez, 1988). The quality and utility of analytical results depend upon many elements of the research protocol. Samples must be collected over spatial and temporal scales that capture systematic and stochastic variations in the parameters under study. Numerous precautions must be taken to maintain the integrity of samples and minimize contamination. Because each analytical technique has its strengths and limitations, it is important to perform several complementary techniques on the same field samples. Surface water contamination by toxic elements is often demonstrated by comparing total concentrations in waters receiving anthropogenic inputs to concentrations from upstream, pristine waters. Ultraclean sampling, handling, and analysis and careful comparison with reagent and instrument blanks are necessary to obtain reliable trace metal data from surface waters. Failure to follow these procedures can yield estimates of toxic metal concentrations that are two orders-of-magnitude too high (Benoit, 1994). In combination with ultraclean techniques, resolution of naturally-occurring isotopes (e.g. Erel et al., 1991) and rare earth element profiles (Olmez et al., 1991) can be used to resolve anthropogenic inputs from those derived from natural sources. Characterization of natural organic matter is needed to evaluate its ability to form complexes with toxic metals, form covalent compounds with pesticides, participate in dissolution/precipitation reactions of minerals, serve as a carbon source for bacteria, and form chlorination byproducts during drinking water chlorination (Aiken and Cotsaris, 1995). USGS scientists have been at the forefront of developing new and innovative means of collecting (Aiken et al., 1992) and characterizing (Leenheer et al. 1995) natural organic matter, and have developed a comprehensive

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understanding of its role in natural biogeochemical processes (Averett et al., 1989). In addition, Nitrogen-15 and carbon-13 Nuclear Magnetic Resonance (NMR) methods to obtain fundamental information regarding natural organic matter functional groups are currently under development (Thorn et al., 1992). Capillary electrophoresis, which separates organic molecules according to molecular charge and hydrodynamic radius, has been shown to resolve natural organic matter sub-fractions (Garrison et al., 1995). In combination with established detection methods, capillary electrophoresis should be an effective new tool for characterizing natural organic matter. Gas chromatography, in combination with electron capture detection or with mass spectrometry, represents one of the most powerful analytical techniques available today. Neutral, hydrophobic organic contaminants are most amenable to such analysis. In the case of polychlorinated biphenyls (PCBs), resolution of individual congeners at environmentally-relevant levels is now possible (Eganhouse and Gossett, 1991). Changes in congener profiles in space and in time are now widely used to explore the physical, chemical, and biological processes acting upon them. Ionized organic contaminants frequently require derivatization and sample enrichment. The determination of anionic surfactants in sewage effluent and ground water samples has, however, been effectively demonstrated (Field et al., 1992). CRITICAL AREAS OF RESEARCH Better understanding of the processes that affect contaminant migration are critical to cleaning up the nation's hazardous waste sites. Good characterization data are required to design effective and efficient remediation systems. Improved understanding of processes such as adsorption, desorption, facilitated transport, and sediment-water interactions are required so that superior systems for removing or immobilizing contaminants can be designed and developed. Characterization of sites with separate phase contaminants such as light nonaqueous phase liquids (LNAPLs) and dense nonaqueous phase liquids (DNAPLs) is critical to remediation of sites contaminated with organics. The principles developed within the petroleum industry regarding petroleum migration and

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extraction from the subsurface have been, and should be applied to studies of contaminant fate and transport and remediation designs. Improvements in the understanding of subsurface heterogeneities also will be required for better predictions of contaminant fate and transport. A major research need with respect to characterizing biological processes in the subsurface is to improve the fundamental understanding of microbial populations in context with the heterogeneous physical and chemical conditions of the subsurface. Questions remain as to how microbial populations develop and are maintained in aquifers through periods of environmental stress caused by insufficient substrates, nutrients, moisture, or other undesirable conditions. Associated with these questions are the issues of microbial transport and survival within saturated and unsaturated, aerobic and anaerobic zones, as well as the issue of relating microbial populations to flow patterns within an aquifer. More tools are needed to characterize the subsurface non-invasively or with minimal invasion. Improved field screening of contaminants could save millions of dollars. Development of tools to characterize sites with mixtures of contaminants will be necessary as more is learned about the nature of contaminant problems. Future research must integrate the understanding of surface and subsurface processes and closely examine the interaction between ground water and vadose zone processes. Hazardous waste systems must be examined as a whole by integrating concepts from a variety of fields. OPPORTUNITIES FOR THE USGS The USGS has made significant contributions to the understanding of the hydrologic cycle and the subsurface in both pristine and contaminated settings. This research has concentrated on improved understanding of processes rather than the creation of new technologies. Future opportunities within this arena will likely be extensions of previous or existing work, rather than totally new endeavors. Process-related research topics of broad scope that require the multidisciplinary resources and expertise available within the USGS are listed below:

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• Hydrological, biological and geochemical processes within fractured and heterogeneous media. • The effects of physical form or phase (e.g., NAPLs, gases, sorbed) on the availability of contaminants to geochemical and microbial actions and reactions. • Incorporation of biological processes into contaminant fate modeling. • Microbial transport through the subsurface. • Microbiological adaptation and contaminant degradation under conditions of typical subsurface physical and chemical stresses. • Development of analytical tools to evaluate chemical, hydrological, and biological processes directly within the subsurface environment. • Improved prediction capability for heterogeneities in the subsurface. • The effect of nutrient levels (nitrogen and phosphorus) on the chemistry, biology, and transport of contaminants in surface waters. • Sediment-water interactions, such as contaminant entrainment in sediments by particle settling, resuspension by storms, and release caused by chemical and biological processes within the sediment. • Direct photolysis of contaminants in surface waters, and the reaction of contaminants with reactive species generated through the photolysis of organic matter and other natural solutes. • The production and decomposition of natural organic matter.

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4 Remediation

INTRODUCTION Although the USGS is unlikely to become directly engaged in either developing or implementing technologies for remediation, it is likely that the USGS increasingly will be called on to support cleanup efforts by providing high quality data on natural systems and processes necessary for the proper design of remediation options, and to evaluate the efficacy of remediation efforts through field measurement programs. Moreover, the USGS is well positioned to further understanding of intrinsic bioremediation, the process that occurs when natural conditions at a contaminated site promote in situ bioremediation in the absence of engineering intervention. With appropriate monitoring, intrinsic bioremediation can be a successful treatment strategy if the rate of contaminant destruction outpaces contaminant migration such that the contaminant plume shrinks over time without causing a significant threat of exposure. Thus, it is considered appropriate for the USGS to participate in the identification and solution of problems associated with remediation of contaminated land and water resources. This chapter briefly reviews the state-ofthe-art of remediation technology and monitoring, identifies critical areas for remediation research, and describes specific research opportunities where the USGS can contribute to meeting the challenges of remediation contaminated sites.

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STATE-OF-THE-ART IN THE FIELD Remedial technologies can be grouped into the following categories, based upon levels of development as well as effectiveness in providing environmental remediation. • Emerging Technology. A technology that requires additional laboratory or pilot-scale testing to document the technical viability of the process. • Innovative Technology. A technology for which cost or performance information is incomplete, thus impeding routine use. An innovative technology may require additional full-scale field testing before it is considered proven and ready for commercialization and routine use. • Established/Available Technology. A technology that is fully proven, in routine commercial use, and for which sufficient performance and cost information is available. The development and application of many remedial alternatives has occurred largely in response to the mandates of state and federal regulations such as “Superfund” (CERCLA and SARA), as discussed in chapter 2. The range of options that has become available includes emerging concepts with bench-scale testing, field demonstrations, and techniques approved for full-scale use and commercialization. For example, the state of technology development for options applicable to soils, sediments, ground waters, and other matrices (Table 4.1) includes both ex situ and in situ techniques that are based on biological, physical, and chemical processes, either in separate or combined systems. Technology applications for soils, sediments, and ground waters have been, or are being developed to destroy, detoxify, separate, recover, or immobilize contaminants according to their functional identity (Figure 4.1 and Figure 4.2). Many of these same technologies also may be applied to sludges and dredge spoils. In addition, augmentation and/or enhancement may be required to optimize in situ biological and physical-chemical techniques, and in situ immobilization may be but one consequence of an applied technology rather than its primary intent. Therefore, techniques for contaminant access, isolation or capture, as well as extraction and ex situ

Source: U.S. Environmental Protection Agency, 1994; Kovalick, 1994; and WASTECH, 1995.

Table 4.1 Status of Remedial Technologies (Soils, Sediments, Sludges, Ground Waters, and Solid-Matrix Wastes) Innovative Established/Available Emerging Bench-Scale Testing Field Demonstration Selected for Remediation Limited Full-Scale Use or Limited Data In situ electrokinetics Radio-frequency heating Thermal desorption Solvent extraction Land treatment X-ray treatment Ex situ furnace vitrification In situ soil flushing Soil vapor extraction Soil washing Dechlorination Electron irradiation Pneumatic or hydraulic fracturing Bioventing Laser-induced oxidation Air sparging In situ bioremediation Treatment wall Slurry-phase bioremediation In situ vitrification Incineration Solidification/stabilization Above-ground treatment

Common Full-Scale Use

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FIGURE 4.1 Technologies applicable to soils and sediments. aqueous-phase treatment, may provide supplemental alternatives for an integrated remedial approach. New remedial technologies continue to be developed (WASTECH, 1995), and the use of innovative options has already surpassed established or conventional alternatives for remediation at Superfund sites. There has been a significant trend toward innovation as new technologies are demonstrated and applied for the remediation of contaminated ground waters,

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FIGURE 4.2 Technologies applicable to ground waters. soils and sediments (Figure 4.3 and Figure 4.4). Moreover, depending on site-specific circumstances, more than one technology or process may be needed to achieve remediation goals. Combinations of technologies that have already been implemented at Superfund sites include (U.S. Environmental Protection Agency, 1993a, b): • soil washing, followed by bioremediation, incineration, or solidification/ stabilization of soil fines; • thermal desorption, followed by incineration, solidification/stabilization, or dehalogenation to treat PCBs; • soil vapor extraction, followed by in situ bioremediation, in situ flushing, solidification/stabilization, or soil washing to remove semivolatile organics;

FIGURE 4.3 Status of treatment technologies at Superfund sites. Source: EPA, 1994; Kovalick, 1994.

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FIGURE 4.4 Status of alternative technologies for Superfund Remedial Action. Source: EPA, 1994; Kovalick, 1994.

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• dechlorination, followed by soil washing for inorganics; • solvent extraction, followed by solidification/stabilization or incineration of extracted contaminants and solvents; • bioremediation, followed by solidification/stabilization of inorganics; and • in situ flushing, followed by in situ bioremediation of organic residuals. Nearly 50 emerging, innovative, or established/conventional technologies have been identified for contaminated soils, sediments, sludges, and ground waters (U.S. Environmental Protection Agency, 1993b). Many include in situ and ex situ biological, thermal, physical, and chemical processes, which are supplemented by techniques primarily used for containment, separation, or enhanced recovery or off-gas treatments. Each involves a variety of challenges, including cost, performance, technical, developmental, and institutional issues. Collectively, these challenges constitute screening factors influencing the efficacy of a particular remedial technology, and range from overall cost to community acceptability. Some of these factors pose performance-related questions, whereas the others present opportunities to assign comparative ratings (i.e., better, average, worse, or inadequate information) based on available knowledge, experience and expertise. Such an approach has led to the development of an interagency DOD/EPA remedial technologies matrix (U.S. Environmental Protection Agency, 1993b), and resource documents that describe remediation case studies (U.S. Environmental Protection Agency, 1995). CRITICAL AREAS FOR RESEARCH Technology development and deployment are in considerable flux, even for those technologies ranked as having full-scale or conventional status. Further, technologies currently not highly rated in terms of various screening factors may become attractive in the future as more is learned. There is considerable opportunity for additional discovery in terms of basic scientific principles and their applications to remediation, whether for characterization of processes or the environmental setting that

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is the ultimate target for remediation. For example, heterogeneities within hydrogeological environments, and the complexities of contaminant partitioning behavior, can hinder the effectiveness of remediation technologies in the field. Therefore, in order to improve understanding of contaminant transport and fate within natural systems, research priorities should emphasize studies that employ direct measurements from field investigations rather than from more easily controlled laboratory experiments. A research area that would have major impacts on improved application of in situ remediation technologies is the development of methods for evaluating remediation success or progress in the field. Currently, evidence that applied remediation technologies are responsible for the removal or detoxification of contaminants is difficult to collect and rarely convincing (National Research Council, 1993 and 1994b). Similarly, as the limitations of currently applied physical, chemical, and biological remediation processes, including the uncertainties of retardation, attenuation, and/or mobility enhancement mechanisms, become more evident through the increasing numbers of laboratory field demonstration studies, it will become clear that future priorities in field-scale development should be directed toward application of combinations of remediation technologies or remediation technologies that are designed to work together with natural attenuation processes. Growing out of these integrations will be the need to understand the complex responses resulting from multiple processes, in order to more confidently evaluate the overall effectiveness of complex remediation schemes. OPPORTUNITIES FOR THE USGS The research challenges associated with remedial technologies represent an important avenue of opportunity for the USGS, because the experience and expertise required to assess and characterize the nation's water resources as impacted by hazardous materials are the same as those needed to successfully engage in the assessment of the effectiveness of remediation. Therefore, the USGS should embark on a focused strategy to position itself as an active participant in decisions that involve environmental assessments associated with contaminated soils, sediments,

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ground waters, and surface waters, and the application of innovative technologies for effective remediation. This strategy is consonant with the USGS's general objective to expand the body of scientific knowledge relevant to the behavior of hazardous materials in the environment. The USGS, as the principal federal nonregulatory organization charged with investigating water resources problems, is positioned to extend its national agenda beyond characterization of contaminants and their transport and fate in the natural environment, to the science and technology of source remediation. This added dimension is justified because one of the historical strengths of the USGS has been its long-term involvement in field research. In the area of hazardous waste remediation, field research should continue to have a high priority, with the understanding that laboratory studies that support work in the field will also be necessary and beneficial. In establishing an agenda for future research emphasis, the USGS should not specifically direct efforts towards the development of new remediation technologies, but should capitalize on its field experience and research capabilities in evaluating the effectiveness of technologies developed and implemented by others. Because the USGS is not directly associated with contaminated site liability or directly responsible for cleanup, it should play a significant role in providing objective and unbiased assessment of results. This will require close coordination among researchers involved in diverse applications. For example, researchers studying metals transformation in anoxic sediments may greatly benefit by frequent communication with those studying acid mine drainage in surface waters and vice versa. The programmatic structure of the USGS also is well suited to integrating short- and long-term field studies with directed laboratory research in the area of hazardous materials science and technology. The Federal-State Cooperative Program supports specific site-related studies that are short term and may include site characterization and monitoring as well as the evaluation of remedial technologies. The evaluation of more broadly applicable field methods and techniques may be funded by the Department of Defense Environmental Contamination Program, whereas the Core Hydrologic Research and Toxic Substances Hydrology Programs provide long-term funding that supports scientific work with more prospective potential. Thus, the potential for integration of exper

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tise across disciplinary boundaries, and the associated ability to perform multidisciplinary short- and long-term research using field sites for the purposes of advancing the science and technology of hazardous materials research, may be one of the USGS's most valuable assets.

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5 Mathematical Models and Decision Support

Mathematical models are indispensable tools in ground and surface water hydrology. They provide a basic framework useful in codifying knowledge concerning the fundamental laws describing the flow of water and mass and energy transport. Beyond their use in fundamental studies of hydrologic processes and theory, models assist in decision making in relation to site- or region-specific problems. In such applications, models can reduce the uncertainty in decision making by providing a rational, self-consistent structure for data collection, site characterization, hypothesis testing, quantification of uncertainty, risk assessment, and the evaluation and design of remediation alternatives (National Research Council, 1992). Through the years, the USGS has undertaken a spectrum of modeling activities, including those that pertain to contaminant transport and multiphase flow in ground and surface waters (Appel and Reilly, 1994). This chapter examines recent USGS activities in modeling related to hazardous materials research and examines opportunities for future work. Three general modeling types considered include: (1) predictive flow and transport models and their applications, (2) decision support models, and (3) optimization/decision support systems. The predictive models include those concerned with the solution of the classical differential equations for single and multiphase flow, as well as mass and energy transport. These models commonly find their most important applications in the elucidation of basic theory and the evaluation of actual problems. Optimization models represent mathematical approaches for the analysis of very complex systems with the specific view of finding the best course of action

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from a set of alternatives. They differ from the trial and error approach of conventional models in that they represent a more formal mathematical approach to decision making. A decision support system can be broadly defined as a collection of data, models, process information, and other expertise that is integrated in a unified way for analysis and evaluation of problems and alternative solutions to these problems. Decision support systems differ from the conventional modeling approaches in that they typically address less well-defined problems, managerial or planning in nature, without established approaches for solution. In addition, they stress flexibility to allow for ongoing changes in the situation or approach of the decision maker (Sprague and Carlson, 1982; Newell et al., 1990). Because the USGS has been historically active in the development of mathematical models for ground water flow and transport, and because similar activity for surface water quality models has been (at least in recent years) limited to the integration of existing models in decision support systems, the following discussion of predictive models for water quality is largely limited to ground water, whereas the analysis of decision support systems considers both ground water and surface water models. PREDICTIVE FLOW AND TRANSPORT MODELS Flow and transport models are now widely utilized and accepted as tools for basic scientific study and management of hazardous materials in surface and ground water environments (Friedman et al., 1984; National Research Council, 1990b). In assessing the state-of-the-art with respect to modeling and opportunities for research, this study refers to and builds on a recent National Research Council assessment of modeling carried out for the U.S. Army (National Research Council, 1992). The development of conventional modeling approaches is cast in the same framework developed earlier, with a pathway of evolution leading from process discovery to model application. Within the context of this modeling approach, process discovery considers the mathematical formulation of the processes of interest. Process description refers to detailed studies to examine how the process works, the importance of one process relative to another, and the worth

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of modeling parameters (National Research Council, 1992). The application of models usually involves the use of the model in a predictive mode to sitespecific problems of assessment and remediation. The extent to which models can be productively used in practice is mixed. In many cases, such as multicomponent flow involving NAPLs and water or multispecies transport, there are usually insufficient data to routinely apply models in a predictive mode. Models can be used productively for sensitivity analysis to better understand real problems, however. In other areas, such as aquifer analysis, models are used routinely in practice. In terms of overall directions for research, ground water modeling issues with respect to problems of saturated and unsaturated flow in simple porous media therefore do not present the most important challenges. Similarly, hydrologic and hydrodynamic models for the quantity and velocity of surface water flow provide only a portion of the information needed to predict pollutant fate and transport in surface water systems, with effective representation of chemical and biological transformations also required. The difficulties in using more sophisticated models is well known, and it is in these areas where the greatest potential remains for research at the USGS. Table 5.1 represents the committee's view of progress with respect to some of the most important flow and mass transport processes in ground water. The list of processes is divided into three parts, representing a set of flow processes, a set of mass transport and chemical mass transfer processes, and a set of other, generally more complicated processes. This latter category represent complexities in the manifestation of processes due to fractures and coupling among the flow and transport processes. Saturated Flow in Porous Media A previous National Research Council report determined that the state of knowledge with respect to the saturated flow of ground water in porous media is well developed, with the bulk of research activities at the applications end (National Research Council, 1992). This finding is not surprising given that problems of this type have formed the scientific basis of hydrogeology for more than 100 years. The pioneering efforts in the development of numerical approaches for the simulation of complex aqui

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fer systems began in the USGS with the work of Pinder and Bredehoeft (1968), Pinder and Frind (1972), and Trescott et al. (1976). Significant efforts have continued within the USGS in the area of aquifer simulation. The most well-known development in this area is MODFLOW (McDonald and Harbaugh, 1988), which is the industry standard code for aquifer analysis. In recent years, USGS efforts have been concerned with improving the efficiency and robustness of MODFLOW (e.g., Hill, 1990), and expanding the codes capabilities through useful extensions such as parameter estimation procedures in MODFLOWP (Hill, 1992), and the capability to treat narrow horizontal barriers. A related code, directly relevant to the analysis of contamination problems, is MODPATH (Pollock, 1989). This code takes flow information from MODFLOW and computes three-dimensional pathlines. It is used extensively in industry to estimate directions and spreading rates for plumes and for the design of pump-and-treat systems. The potential for scientific work in this area is on the applied side with prospects for algorithm refinement, improved design interfaces, and the further development of related “packages.” The MODFLOW family of codes in particular represent a significant achievement of the USGS. However, USGS efforts in recent years appear to have lagged behind many of the newest developments from other government agencies and industry. It is believed that the USGS must reassert its leadership role in the enhancement of this code, its distribution, and training in its use. Efforts should focus on ease of use, visualization technologies, and package integration. Additionally, there is a need for better links between data input for model codes and real-world spatial data. For example, the USGS is ideally suited to improve the somewhat crude links between model inputs and GIS systems. Such efforts would be very useful to those working in the area of hazardous waste. Unsaturated Flow in Porous Media Unsaturated flow processes refer to the flow of a single fluid (in this case, water) coexisting with a static gas phase. Traditionally, work on this problem has resided in the domain of soil physicists concerned with local scale fluxes of water in the vadose zone.

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Flow in an unsaturated medium is more complicated than saturated flow. Hydraulic conductivity, which is constant for saturated flow, varies as a function of moisture content and ultimately pressure head. In order to model unsaturated flow, information therefore must be provided on the form of soil hydraulic conductivity curves (hydraulic conductivity versus pressure head) or soil-water characteristic curves (soil moisture versus pressure head) (National Research Council, 1990b). Because the resulting equation of flow is generally nonlinear, the possibility of analytical modeling of flow is limited to exponential hydraulic conductivity curves that lead to linearized forms of the flow equation. Numerical solutions to forms of the unsaturated flow problem have existed for a long time (e.g., Freeze, 1969; Freeze, 1971). There is relatively limited theoretical work underway for simple unsaturated flow problems. Research is now focused on problems involving dual porosity systems that develop due to the presence of fractures or macropores, and the more complex problem of mass transport through porous media. Although this area of modeling research has not received a high priority within the USGS, there has been work in the development of unsaturated flow and transport codes (e.g., Lappala et al., 1987). Much of the most recent theoretical work in unsaturated flow is being carried out by the national laboratories (e.g., Lawrence Berkeley and Sandia National Laboratories) in relation to the proposed high-level nuclear waste repository project at Yucca Mountain, Nevada. In terms of code development for the assessment of industrial problems of contamination, much of the existing work is being conducted or sponsored by the U.S. Environmental Protection Agency and the U.S. Department of Agriculture. Multiphase Flow in Porous Media In this report, multiphase flow is used to refer to the simultaneous flow of water and other liquids or gases. Examples of these problems include the flow of a nonaqueous phase liquid (NAPL) such as gasoline in a medium that is saturated or partially saturated with water, or simply water and gases in the unsaturated zone. Given this report's emphasis on

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the USGS hazardous materials initiatives, the discussion will be restricted to NAPLs. The basic theory of multiphase flow was developed in the petroleum industry. These fundamental concepts were adopted in the 1980s by hydrogeologists concerned with modeling the migration of NAPLs and developing technologies for their remediation. The NAPL problem, however, provided significant challenges because of the range in properties of organic contaminants, and the complex interphase mass transfers due to volatilization or dissolution of soluble compounds. Several theoretical approaches were listed in National Research Council (1992) as available to model multiphase flow of contaminants. These include: sharp interface approaches, immiscible phase approaches incorporating capillarity, and compositional models that incorporate interphase transfer. Much of the ongoing research in the field is targeting the development of compositional models. However, the U.S EPA is sponsoring the development of simpler sharp interface models for the application to practical problems. The inherent complexity of multiphase models and relatively limited availability of appropriate flow parameters for various materials of interest has unfortunately limited the application of these models. In industry, there is nonetheless a history of modeling experience with immiscible approaches, using codes like SWANFLOW (Faust, 1985; Faust et al., 1989) and ARMOS (Parker et al., 1990). Table 5.1 reflects the need for considerably more work before the modeling technology evolves to a completed state, however. Significant opportunities remain in the modeling and estimation of field parameters related to multicomponent systems. Continued work can be justified on the basis of fundamental interest in science, and the seriousness of the problem posed by LNAPLs and DNAPLs. Historically, little modeling work of this kind has been undertaken by the USGS. The main emphasis of research in the Toxic Waste Hydrology Program related to multiphase contamination problems has been in the geochemical and microbiological investigations of an oil spill at Bemidji, Minnesota, and a gasoline spill in New Jersey—both influenced by the unique compositional and chemical characteristics of organic contaminants. Given the recommendation of this report that the USGS move into the field aspects of remediation, and the large number of sites where multiphase contamination is present, there is a critical need for more research on

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multiphase problems and for the development of expertise in modeling to support this work. Advection and Dispersion Advection and dispersion together account for the physical transport of mass from one point to another in a ground water system. Although research on aspects of dispersion began in the 1950s, the first quantitative description of advection and dispersion were published by Bear (1972) and USGS scientists (Bredehoeft and Pinder, 1973). Although the mathematical framework for describing dispersive processes has been known for more than two decades, it has been only in the last few years that these processes have been understood with the confidence represented in Table 5.1. As National Research Council (1992) points out, the main difficulty in this area has been in explaining the complexity of dispersion at various scales. Although theoretical studies of macroscopic dispersion paved the way, it has been the large-scale field experiments at Canadian Forces Base Borden (e.g., Mackay et al., 1986, Sudicky, 1986) and the USGS Cape Cod research site that have provided the most important new insights on field-scale mass transport. Mass transport models are now used routinely to model advection and dispersive processes. Analytical approaches work very well for simple problems and have formed the basis for practical inverse methods (Domenico and Robbins, 1985; Ala and Domenico, 1992). More complex problems must rely on powerful numerical approaches that are embodied in industry-standard codes like MOC (Konikow and Bredehoeft, 1978). The number of theoretical studies of advection and dispersion has begun to decrease after decades of research elucidating the key features of these processes. Work continues on the development of sophisticated numerical approaches that overcome limitations with the current generation of codes. It appears, however, that much of this work is being conducted outside of the USGS, with noteworthy efforts at the University of Waterloo, Lawrence Berkeley National Laboratory, and the University of Alabama.

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Work remains to be done in this area, although much of the future emphasis will likely shift to model applications. The USGS could productively work in the area of new modeling technologies through the development of refinements designed to improve the robustness and usability of models. Radioactive Decay, Biological Processes, and Multiphase Interactions A variety of chemical, nuclear, and biological processes influence the transport of mass in geological systems. Due to the number and complexity of these processes, the list in Table 5.1 is illustrative rather than comprehensive. As indicated previously (National Research Council, 1992), a few simple processes such as radioactive decay are well known and can be modeled with relatively little uncertainty. Several other transport processes that are represented generally as biological processes and multiphase interactions are generally poorly known, however. Work to describe these latter groups of processes constitutes a major new focus of the hazardous substances programs at the USGS. Generally speaking, most of the key processes have been “discovered.” Whether the processes involve biotransformation, surface reactions or mineral dissolution/precipitation reactions, there are valid mathematical representations of the processes in terms of several key parameters. Significant gaps in knowledge exist, however, in terms of the complex interactions that may occur among constituents, and with natural geological materials. The USGS efforts in many of the field-oriented programs are targeted towards understanding diversity and complexity in biological systems, as well as chemical reactions involving organic and inorganic chemical systems. Limited knowledge of biological systems means that the fate of only a few common contaminants under relatively simple geochemical conditions can be predicted with any certainty. Data necessary to model the kinetic character of biological reactions are rudimentary. Although considerable research is needed to fully understand the operation of biological systems, some transport models have attempted to include biological effects. The simplest models represent the biotransformation

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of organic compounds simply as a first-order kinetic process (Bouwer and McCarty, 1984). Other more mechanistic transport models (e.g., Borden and Bedient, 1986; Molz et al., 1986) incorporate kinetic models of the microbial populations. However, the kinetic (and other necessary) parameters for these formulations are poorly known and there has yet to be a field-scale validation of the approach. Of all the chemical reactions that can affect contaminant fate, sorption is among the most important. Sorption effectively couples mass in solution to the solid surfaces, and in so doing can retard the rate of contaminant migration relative to that of ground water. Compared to biological processes, the problem of parameterizing such a system is a little less severe for two reasons. First, an extensive base of information on the equilibrium partitioning of hydrophobic organic compounds, appears to work reasonably well in ground water systems (Curtis et al., 1986). The situation is complicated, however, by the fact that desorption reactions often occur at rates different than sorption reactions. Second, it is believed that for engineering decisions, metal sorption can be modeled using site-specific estimates of distribution coefficients. It is generally conceded, however, that the K d approach to modeling the surface behavior of metals is seriously flawed. Some of the first field oriented attempts to adapt more sophisticated process models (e.g., surface complexation, or cation exchange) are underway at Cape Cod (e.g., Stollenwerk, 1991). Another type of multiphase process is that involving the redistribution of mass among the solids, other liquids, and gases that water encounters in moving through a ground water system. The simplest models of these processes are based on equilibrium mass law relationships for which relatively complete data bases of equilibrium constants are available. However, if the reactions of interest are best described using a kinetic viewpoint, then there are virtually no existing data to model these processes. The state-of-practice in the application of transport models that can account for nuclear, chemical, and biological processes has advanced very little in recent years. Most codes used in applications typically work with a small subset of the possible reactions, and avoid coupling among the constituents through the use of first-order kinetic rate laws for biotransformation reactions, and simple equilibrium linear or Freundlich models for

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sorption. More comprehensive codes have been developed (e.g., Lin and Narasimhan, 1989), but they are rarely used in solving practical problems. Beyond the considerable problem of collecting the necessary data to use the more complex models at a given site, is the more fundamental research need to validate the modeling approach at both laboratory and field scales. Significant opportunities remain for field-oriented research in the elucidation of processes and the characterization of mass transfer parameters. The existing program in hazardous materials is exceptionally strong in this area and should continue. Progress in the modeling of complex geochemical systems has been much more modest and could be improved to take advantage of the impressive field-scale contributions. Coupled Flow Processes The term “coupled flow” is used to describe interdependent flow and transport processes where, for example, the flow of water depends strongly upon the concentration and/or temperature distributions, and the concentration and/or temperature distributions depend upon the flow of water. In even more complex situations, coupling may involve flow, transport, and mechanical contributions. The details of coupled flow processes will not be described in this report; interested readers can refer to a collection of papers on this topic by Tsang (1987). Progress in the mathematical modeling of these kinds of problems has been mixed. For certain problems, such as the interaction between fresh water and sea water, there has been considerable effort in model development. In general, however, progress in modeling complex coupled processes is relatively limited (see Table 5.1). The most serious modeling effort in the area of coupled flow has been that associated with the proposed high-level nuclear waste repository at Yucca Mountain, Nevada. In particular, the coupled thermal hydrologic models V-TOUGH and NUFT likely will form the technical basis for the license application. Historically, the USGS has played a role in the development of codes to simulate coupled phenomena. Examples include the work of Kipp (1987) with HST3D and Voss (1984) with SUTRA. In recent years, it appears that little further development work has been undertaken on these

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codes. In relation to conventional problems of ground water contamination, recent modeling studies are examining the density driven transport of dense hydrocarbon vapors in partially saturated media (Mendoza and Frind, 1990a,b) or unstable mixed flows (Schincariol et al., 1993). Coupled process modeling is emerging as a fertile area for both theoretical and applied research. Coupled systems represent the new frontier for research in computational hydrogeology. The field has been slow to develop in part because of the high level of sophistication needed to solve systems of partial differential equations, and because of the tremendous computational power required to solve even relatively small problems. Run times of days on state-ofthe-art workstations, and many hours on supercomputers are the norm for even quite simple problems. The lack of clearly identified practical problems has also tended to limit development of the field. The emphasis on thermal approaches to contaminant remediation is one area likely to spur new research, however. Flow and Transport in Fractured Media Research efforts to model flow and transport in fractured media have been ongoing for several decades and are continuing. The main motivation for this work is the importance of fractured media in relation to contamination problems, and the scientific and computational challenges in the modeling of fractured rock systems. The earliest combined flow and transport models represented fractured systems either as an equivalent porous medium, or as a discrete network of fractures. With the first of these approaches, it is assumed that the behavior of the fractured system is describable in a straightforward manner with porous medium models once an appropriate choice of parameters is made. In the second approach, each fracture is represented discretely in terms of its geometry, mean aperture roughness, and interconnection with other fractures. Codes of this type (e.g., NAPSAC, UK Harwell; FracMan/MAFIC, Golder Associates, 1988) have been developed to handle flow and transport in relatively large and complex fracture networks, and have been applied to assess practical fractured rock problems related to the Stripa Project in Sweden.

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One limitation of the current generation of discrete fracture codes is the inability to handle fracture matrix coupling. Work underway at the University of Waterloo (Sudicky and McLaren, 1992), however, has led to a powerful new modeling approach that incorporates fracture matrix coupling. This work exemplifies the continuing interest in fractured media applied to many different types of process modeling. Fracture flow and transport codes are also being used in DOE sponsored studies on both the Waste Isolation Pilot Plant (WIPP) site in New Mexico and the Yucca Mountain site in Nevada. The complexity of basic theory and computational burden associated with the discrete modeling approaches has limited progress in research. Considerable potential remains in the study of fractured rock problems, however. Detailed information on the geometry and hydraulic characteristics of fracture networks is a necessary requirement for the application of sophisticated modeling codes. Not surprisingly, acquiring this kind of detailed information requires careful field measurements. The USGS has taken a valuable step forward in this regard with the initiative at the Mirror Lake Basin in New Hampshire. The new downhole, and cross-hole testing technologies being developed at this site will be of great assistance in the characterization of fractured rock systems. Issues in Flow and Transport Modeling at the USGS The leadership role that the USGS has played in the development of modeling methodologies is reflected in the extent to which models like MODFLOW, MODPATH, MOC, and others have been accepted by industry. This role has diminished in recent years, however, as the national laboratories, other government agencies (e.g., U.S. EPA, U.S. Army), universities and private industry have taken the lead role in many areas of the modeling field. In vitally important areas of multicomponent flow and transport, and reactive transport modeling, the USGS has minimal ongoing efforts. The USGS should reinvigorate its internal modeling capabilities, and add to existing capabilities as practicable. Besides the addition of personnel, there is a critical need for new facilities to support high-speed

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computation and visualization. Advanced modeling capabilities are a requirement for the detailed, field-oriented research programs now operated as part of the toxic materials program. The design of appropriate experiments, the interpretation of experimental results, and the development of initiatives in remediation all require the integration of modeling. It is not in the interest of the hazardous materials programs to be seen only as an investigator of fieldoriented processes. The emphasis in research in many areas is rapidly shifting away from process studies toward applications involving models. It is important for the USGS to recognize this change in emphasis and diversify activities to some extent toward the modeling areas. This diversification makes sense scientifically and tactically, for it is an imperative to develop new modeling capabilities within the districts as a follow on to the successful Regional Aquifer-System Analysis (RASA) Program. Mathematical models for flow and transport are most useful for decision support when they can be interfaced with an effective data base management system. The ability to allow flexible data input, storage, retrieval, analysis, and visualization is an important part of advanced modeling systems. One important development in recent years is the ability to interface models with Geographic Information Systems (GIS). An obvious development of this capability would involve codes like MODFLOW and MODPATH. Basin-scale hydrologic models are particularly rich in these kinds of applications, including topographically-based modeling of watershed stream flow with digital terrain data (e.g., Hornberger and Boyer, 1994) and nonpoint source identification, modeling and control (e.g., Sivertum et al., 1988; Vieux, 1991; Tim et al., 1992; Srinivasan and Engel, 1994; Srinivasan and Arnold, 1994; Yoon and Padmanabhan, 1994). DECISION SUPPORT SYSTEMS In most current applications and usage, the concept of a decision support system is associated with computer-based tools and software packages used in support of decision making. However, decision support in a more general sense involves the unified application of information, expertise and experts from several related fields (such as hydrology,

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geology, geochemistry, statistics, and database management) for problem solution. To a growing extent, these are the types of environmental problems faced by the USGS and its cooperators, where a range of hydrologic, chemical, biochemical, and economic factors must be integrated in a consistent, but often unique manner, in different problem applications. A decision support system for an environmental problem can serve as a platform for integrating existing scientific knowledge and data sources on chemical transport, transformation, and exposure processes in the natural environment, and allow this information to be used to address critical decisions and policy concerns. It also can aid in the ability to characterize and assess current water quality problems, predict the effect of alternative management strategies, and guide in the selection and implementation of these management strategies. For example, in watershed-scale assessments, a decision support system would allow users to: a.

b.

c. d. e. f. g. h.

input site or watershed data on hydrogeologic characteristics, meteorology, water flow, contaminant sources, and water quality directly or through remote data collection systems; access, manipulate, and utilize data files, including those from Geographic Information Systems (GIS), for visualization and input into predictive models; call and test alternative models for chemical transport and transformation for the site or watershed; allow assessments of the reliability and uncertainty of model predictions; use the models to examine alternative management options and aid in the selection of optimal strategies; identify data needs and the value of information to improve models and associated decisions; track ongoing implementation and monitoring of the management strategy; and encourage education and participation in the decision process by a wide range of user groups.

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Although this or a similar list of objectives can provide a target for much of the current research and development in decision support systems, available systems to date have only been able to provide some of these capabilities. Development efforts by the USGS should focus most appropriately on a subset of these capabilities. For example, automated data collection, input to GIS data base management systems and utilization for site characterization and assessment fit naturally with the historic mission of the USGS for resource description. The tracking of implementation of management strategies is heavily weighted towards the application end of resource management, and may thus involve more significant efforts by agencies such the EPA, DOD, or DOE. Even so, at the discovery end, when new decision support system technologies are developed, these eventual applications must be anticipated. Existing and Potential USGS Initiatives The USGS currently has underway a number of projects to support the development of decision support systems for evaluating surface water flow and quality. The center-piece of the USGS effort is the Modular Modeling System (MMS) of Leavesley et al. (1992, 1994, 1995), developed as part of the USGS initiative on Watershed Modeling Systems. The MMS is an integrated system of computer software developed to support the development, testing, and evaluation of hydrologic and ecosystem impact models for watersheds. It includes a GIS interface for input and management of the watershed data needed for hydrologic and water quality models, libraries for the selection of component models, capabilities for parameter estimation, visualization and statistical analysis of model results, and optimization for determination of management strategies. MMS allows researchers from a variety of disciplines to work cooperatively in the development, testing and application of linked modules in an integrated evaluation framework for multidisciplinary problems. Additional development work for decision support systems addressing surface water problems has occurred in selected projects supported by the state water resources institute programs (e.g., Cheng et al., 1993). In ground water applications, the enormous quantity of site characterization data at many sites requires that predictive models be interfaced

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with effective data base management systems. Decision support systems for ground water fate and transport evaluations have been developed, notably the OASIS system of Newell et al. (1990). The USGS has supported similar efforts through the state water resources institute programs (e.g., Peralta et al., 1992), and significant work has been done by private software firms to enhance the front- and back-end capabilities of the USGS MODFLOW program for more efficient input, output, and parameter estimation. In addition, advanced database management and visualization capabilities have been incorporated into a number of USGS ground water modeling studies. However, a complete and unified USGS effort for ground water assessment, comparable to that of the MMS program, is not in place. In the future, the power of decision support systems to allow analysts and decision makers to synthesize complex data and model problems and visualize the impact of alternative management strategies will grow with the availability of new technologies utilizing 3-D color graphics and perhaps even virtual reality, where a decision maker could travel along with an “insiders view” of a proposed remediation option. For certain components of a predictive model, in which traditional approaches to simulation and data interpretation cannot fully capture important factors and relationships, approaches based on artificial intelligence and expert systems may be appropriate. Applications in ground water science include site characterization, interpretation of geophysical logs, and model selection and calibration (National Research Council, 1990b). Because these advanced computer technologies are evolving rapidly, the USGS should ensure that the scientific information produced by the Survey can be utilized along with these tools. OPTIMIZATION AND DECISION ANALYSIS Predictive models allow decision makers to examine the possible impact of alternative management strategies in a “what if?” manner. Often, however, the suite of alternatives is too large or complex to effectively explore in an ad hoc manner in search of a “best” (or simply “good”) strategy. In this case, more formal methods for strategy selection

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are needed as part of the decision support package. These methods generally fall into the category of optimization or decision analysis tools. Optimization methods have been widely applied to both surface water and ground water problems. Applications have evolved from simple linear, single criteria, deterministic formulations that consider only water quantity, to nonlinear, multicriteria formulations that consider uncertainty and address problems of both water quantity and quality (Hipel, 1992). Numerous formulations have recently been developed to address the design of ground water remediation, focusing on the optimal placement, timing, and flow rates of pump-and-treat capture wells (e.g., Gorelick et al., 1984; Wagner and Gorelick, 1987; Chang et al., 1992; Wang and Ahlfeld, 1994). Optimization is also an important tool for decision support, and research by the USGS has contributed significantly to its advancement. Optimization packages for both parameter estimation and management strategy selection are included as part of the MMS for watershed evaluation, and similar tools can now be interfaced with MODFLOW. These efforts are extremely valuable and should continue. Such an initiative also would be of tremendous industrial and regulatory interest. A second approach to the selection of management strategies, the technique of decision analysis, is similar in many respects to optimization, but emphasizes different aspects of the decision problem. In decision analysis, the emphasis is on the role of uncertainty in affecting the optimal decision, and the role that information can play in reducing this uncertainty. The methods of decision analysis have recently been applied to structure models, data collection, and management decisions for ground water (e.g., Marin et al., 1989; Reichard and Evans, 1989; James and Freeze, 1993), and sediment remediation (Dakins et al., 1994). These methods allow iterative evaluation of ongoing data collection programs in concert with decisions on contaminant control and remediation. They are thus well suited for packages that integrate data-base management, modeling, characterization of uncertainty, and visualization of water flow and water quality problems. An important limitation in the application of optimization and decision analysis methods to the management of hazardous materials in the environment is the inherent time lag in incorporation of state-of-the-art process knowledge and models. The critical geophysical, chemical, and

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biological processes discussed earlier in this chapter are only now being incorporated into contaminant transport models. A further lag occurs in the incorporation of these models into optimization or decision analysis evaluations. For example, virtually all of the optimization and decision analysis applications to ground water remediation cited earlier were for “pump-andtreat” applications assuming dissolved phase contaminant transport with simple adsorption/reaction processes. In this case, the principal source of uncertainty is assumed to evolve from the stochastic character of the subsurface hydraulic conductivity. Although this focus has allowed impressive scientific advancement and methods development, extension of these methods to consider other important processes—such as multiphase flow and microbially- and surface-mediated reactions, and the significant uncertainty present in these processes—is needed to address the many sites where the traditional model and pump-and-treat approaches are inadequate (National Research Council, 1994b). To help speed the transition from research to applied decision models, decision support systems should be designed in a flexible, modular manner, allowing easy substitution and testing of alternative model formulations (as is the design for the MMS). Advances in computing technology, which promote such a flexible, tool-box approach, can thus go hand-in-hand with advances in fundamental process knowledge in promoting more effective and useful decision support systems. An important recent trend in the management of hazardous materials is the desire to include a broader range of participants in the decision making process. Greater stakeholder involvement in problem formulation and evaluation, and decision making is sought for the cleanup and management of contamination on both private and public lands. Methods for considering evaluation by multiple stakeholders have evolved in recent years, including techniques that help facilitate negotiation and conflict resolution (e.g., Ridgley and Rijsberman, 1992; Thiessen and Loucks, 1992). These features can help enhance a decision support system and allow it to be used as a focal point for evaluation in a group decision context.

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DECISION SUPPORT IN THE USGS HAZARDOUS MATERIALS SCIENCE PROGRAM To help delineate the near-term potential for decision support systems to enhance the hazardous materials science research program of the USGS, a brief review of the types of decisions supported in this program is provided. In particular, the range of decision support exhibited in the USGS Federal-State Cooperative and DOD contamination programs, and whether and how research from the Core Hydrologic Research and Toxic Substances Hydrology programs could better interact with these through the aid of decision support systems, are considered. The Core Hydrologic Research program and the Toxic Substances Hydrology program provide the long-term research for theoretical process understanding and the development of general methods and tools. Decision support systems fall within the general domain of such tools; system development efforts thus occur within these more basic research programs. However, the motivation for developing these tools is based, in part, on their potential applications in the Federal-State Cooperative and DOD contamination programs. The Federal-State Cooperative program has encompassed approximately 2,000 projects since it was formally recognized in 1928. Both surface and ground water projects are included, with a somewhat greater portion of the current activity involving ground water problems. Both water flow and quality problems are addressed, though the latter have been more greatly emphasized in recent years. Models of one type or another are used in approximately half of these investigations. Models are used to a greater extent in ground water studies; studies of surface waters and non-point source pollution are more often descriptive in nature. The DOD contamination hydrology program focuses on specific water and soil quality problems at DOD sites. In most cases, these problems involve subsurface soil and ground water contamination, often with the need to consider geochemical processes for metals and organic complexes. The studies are often conducted as part of ongoing remedial investigations, aimed at determining whether the proposed remedy is consistent with the hydrogeologic conditions at the site. Such sites thus provide the need for ongoing data collection for the purpose of tracking remediation

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progress, effectiveness, and compliance; while also providing the opportunity for post-audit confirmation studies of predictive models. This type of ongoing evaluation can be greatly served by decision support systems with integrated data base and modeling capabilities. To address the evolving needs for advanced process representation, these systems will require flexible configurations to allow new models and data configurations to be imported as the need arises. Decision support systems with data base and modeling capabilities can play a direct and important role in expediting the implementation and interpretation of surface water and ground water studies in both the FederalState Cooperative and DOD contamination programs. The capability to accomplish this for surface water evaluation is now in sight, through the work of the USGS initiative on Watershed Modeling Systems and the Modular Modeling System. Similar efforts are underway to enhance the capabilities of USGS ground water models, although a single, unified effort similar to that of the MMS is not apparent. The committee supports such integrated research, and encourages efforts to incorporate and apply this work in the evaluation studies of the hazardous materials science and technology research program. It is clear that the USGS research programs provide the information and expertise necessary for the solution of many critical water quality problems at the site and regional scale. Development of the next generation of decision support methodologies and platforms will allow these solutions to be identified in a more efficient, insightful, and generalizable manner. OPPORTUNITIES FOR THE USGS IN MODELING The field of modeling continues to be a fruitful area for potential research. Given current research directions, several areas in particular should provide significant opportunities within the USGS, including: •

continued development of the MODFLOW family of codes with particular emphasis on the addition of state-of-the-art capabilities for mass transport, more modern solvers, and graphical interfaces;

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• development of robust, stand alone mass transport codes capable of modeling the complexities of reactive chemical transport and the kinetics of microbial processes; • modeling and parameterization of field parameters in relation to NAPLwater systems with emphasis on field and laboratory-based studies as well as modeling-related work; • validation of contaminant fate and transport models using field experiments; • fundamental work in the model investigation of coupled phenomena; and • development of new approaches for modeling flow and transport in fractured rock systems. The area of decision support is a relatively new field that has not been studied extensively. Opportunities for research exist at the USGS in: • the linkage of powerful visualization technologies with the design of remedial systems; • the creation of decision support “tool-boxes” similar to MMS that would enable users to rapidly create and test decision support systems; and • the integration of model and data base capabilities in decision support schemes.

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6 Conclusions

Effective policies for hazardous materials management must consider the development of new methods for the disposal of hazardous materials that avoid unacceptable levels of contamination, as well as methods for dealing with existing contaminated waters, sediments, and soils that have resulted from past inadequate water disposal practices. The USGS, as the agency with primary responsibilities for assessing the nation's land and water resources, has an important role to play in the overall solution to problems associated with the disposal of hazardous wastes. But no single agency, including the USGS, can be charged with answering all of these questions. What is needed is an imegrated, cooperative research effort by several agencies and institutions with relevant roles in the area of hazardous materials management. In considering directions that the various programs within the USGS could follow to resolve important problems in hazardous materials science and technology, this study reached several conclusions and presents a set of recommendations to the USGS. These recommendations can be interpreted as broad guidelines for implementing a plan to maximize the effectiveness of USGS work on hazardous materials. OVERALL PROGRAM FRAMEWORK USGS programs should be responsive to national priorities for addressing problems in the area of hazardous waste. In planning these pro-

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grams, careful attention needs to be given to select critical problems for study, and to appreciate the shift in emphasis in the hydrogeological sciences toward applied problems of a generic nature. Further, there must be a diversification in scientific personnel that includes theorists, computer modelers, and laboratory experimentalists in addition to a field-oriented work force. The USGS should develop a risk-based approach for setting research priorities within the hazardous materials programs. It is important that the agency focus its resources for research on hazardous materials in the hydrologic environment on those issues that have the greatest potential to reduce risks to both public health and natural resources. By no means straightforward, the approach must make full use of decision-support tools as well as the professional judgement of scientists and decision makers from within and outside the agency. Documents such as Science and Judgement in Risk Assessment (National Research Council, 1994d) can provide conceptual guidance that should be of general value in developing the approach. The USGS recently adopted a new strategic planning process into which this risk-based approach can be incorporated explicitly and applied consistently. This process should be useful in ensuring that actions throughout the agency conform with agency priorities set over the coming years. USGS COLLABORATION WITH OTHER AGENCIES The USGS programs in hazardous materials science and technology are very diverse and are carried out within an organizational structure that has evolved over time in response to national problems (Appendix A). The USGS has produced solid scientific results under this structure, and thus there appears to be no reason to undertake significant reorganization. During the course of this study, many instances of cooperation were evident within the WRD (between scientists in the district offices and scientists in the NRP), within the USGS (between scientists in WRD and scientists in the Geological Division), and among federal agencies (among scientists in the USGS and scientists in other agencies and institutions). In the future, cooperation will become ever more important because it will be needed to address interdisciplinary problems and because

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there are likely to be fewer federal resources available to address these issues. The USGS should strive to improve program integration and coordination both within the USGS itself and with other agencies. In addition, other federal agencies often act as "consumers" of USGS research. Satisfying the needs of these agencies is likely to assume increased importance in the future, as the USGS takes on a new role of assessing the efficacy of remediation schemes and methods in relation to hydrogeological settings. Providing leadership in the assessment of long-term results of environmental remediation and the development of modern methods for waste disposal is a role that appears to be particularly fitting for attention by the USGS. SOME CRITICAL ISSUES The USGS has been very effective at characterizing natural processes that control the transport, and to some extent the fate, of hazardous materials released to the environment. The long-term, field-based, mass transport studies of environmental contaminants have been a successful part of USGS research. This type of work should be continued, but expansions into critical areas are essential. First, the USGS should move aggressively to expand the application of their broad-based expertise in characterizing natural processes to include the evaluation of the effectiveness of remediation techniques. Most remediation systems are evaluated only over relatively short periods of time. The USGS should lead the effort to perform the long-term assessments that are essential to both technology refinement and for informed policy decisions. For example, the USGS should undertake work to assess the long-term performance of ground water remediation schemes, the side effects of remediation, and optimal monitoring strategies in various hydrogeological settings. Other critical areas in which the USGS should consider focusing attention include the issue of translocation of contaminated sediments and soils due to extreme events (floods) and, in the area of computer modeling, the refinement of flow visualization techniques and muiticomponent and compositional hydrogeochemical modeling. The USGS also must maintain its strong tradition of interdisciplinary studies. It is critical that the organization provide an integrated

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effort in which physical, chemical, and biological scientists fully cooperate toward mutual goals. EDUCATIONAL OPPORTUNITIES The USGS has provided substantial benefits to students through a variety of informal mechanisms and should strive to increase cooperative activities with universities. Evidence for USGS impact on graduate education includes publications stemming from work in the programs related to hazardous materials that are co-authored by students from a number of universities. Not only has the USGS contributed to the education of professionals who will help solve environmental problems now and in the future, but it has in turn benefitted by association of USGS scientists with other capable scientists at universities and elsewhere. When appropriate, such cooperative arrangements should be encouraged. For example, a professor from a university with strong programs in contaminant hydrology might be “traded” for a USGS scientist for a year. Specific problems could be addressed by graduate and undergraduate students with full or partial USGS funding. The existing relationship between USGS and land-grant universities through the state water resources research institutes provides one mechanism for implementing increased cooperation. ISSUES IN PLANNING AND IMPLEMENTATION This report identifies issues that should be addressed in the context of future planning and implementation of research programs. As an institutional imperative, the USGS must look outward to develop research activities that are relevant to national needs, such as the cleanup of industrial and defense related industries. Thus, it is recommended that the USGS make even greater efforts to communicate and explain results of research on hazardous materials to interested parties, including personnel from other agencies, regulators, industrial workers, and conconcerned citizens. Several approaches might be considered by the USGS to achieve this improvement. There may be opportunities for better part-

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nerships with industries, other agencies, and universities in the future. Care should be taken to maintain long-term follow through with regulators and other stakeholders after a project has been completed. USGS staff will need to communicate better the value of their programs to a non-scientific audience, including Congress, and may need to receive training on how to make effective presentations to lay audiences. The USGS should develop decision-support systems to assess hazardous-materials problems, to assist in the design of remediation programs, and to develop national policies to prevent problems in the future. USGS work in this area should be coordinated carefully with other agencies, for example the Agricultural Research Service, where decisionsupport systems for nonpoint pollution from agriculture are being developed. In respect to research, general priorities should be set with input from other agencies (DOD, DOE, EPA, and appropriate state agencies, for example), scientists with backgrounds in environmental risk assessment, and appropriate non-governmental organizations. Once the priorities are set and a strategic plan is developed, the plan should be submitted to an external scientific panel and reviewed for scientific quality. This type of peer review is needed as part of the process to ensure success of research in the hazardous materials area. The recommendation for peer review at this level is the primary recommendation of this report with regard to the charge to advise on methods for planning for success. The “standard” peerreview measure of success—the review of articles prepared for publication— will serve the purpose of evaluating the success of the USGS programs in hazardous materials science and technology, but only if the strategic direction of the program is focused at the outset on the most important problems for the nation. Continued external peer review of USGS priorities, plans, and strategies related to hazardous materials in the hydrogeologic environment is essential.

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Yoon, J., and G. Padmanabhan. 1994. A decision support system for nonpoint source pollution management using a distributed model-GIS-DBMS linkage. Computing in Civil Engineering: Proceeding of the First Congress held in conjunction with A/E/C Systems '94, ed. K. Khozeimeh. American Society of Civil Engineers, New York, 402-409.

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Appendix A U.S. Geological Survey Water Resources Division Plan for Hazardous Materials Science INTERRELATIONSHIP OF PROGRAMS U.S. Geological Survey (USGS) investigations related to hazardous materials science are conducted primarily through four programs: (1) Core Hydrologic Research, (2) Toxic Substances Hydrology, (3) Federal-State Cooperative, and (4) Department of Defense Environmental Contamination. Together, investigations funded by these programs span a range of effort from long-term research on controlling processes to site-specific studies designed to provide near-term options for existing problems. Two programs, Core Hydrologic Research and Toxic Substances Hydrology, are funded by federal appropriations to the USGS. The other two programs are funded entirely or partially by other federal agencies or state and local cooperators. Details about the planning and decision-making process for each of these programs are provided in Sections 2 through 5 of this appendix. Section 1 addresses the interrelationship of the programs. Activities–Research and Methods Development Research and methods development projects are funded by the Core Hydrologic Research and Toxic Substances Hydrology programs. Both of these programs are line items in the USGS budget. As such, they must meet the goals and objectives outlined in the annual budget submission to the Congress. Within these broad goals, there is considerable flexibility

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to adjust the directions of projects funded by these programs to meet emerging needs. There is also an opportunity to address theoretical problems and questions that require longer-term research. Core Hydrologic Research provides partial support for the National Research Program. The Toxic Substances Hydrology program is conducted by scientists in the National Research Program and District offices. Activities–Site-specific Investigations The Federal-State Cooperative program, also a line item in the USGS budget, is based within Water Resources Division (WRD) District offices. At least 50 percent of the funds for projects within this program are provided by state or local cooperators. Typically, projects funded by this program address problems such as assessing the presence and distribution of contaminants in water resources, predicting the probable effects of alternative actions, and measuring the progress of clean-up operations. Projects must be highly relevant to the over 1,000 cooperators who help support them. The availability of federal funds is the controlling factor in the growth of the Federal-State Cooperative program. Every year there are several million dollars worth of cooperator funds that are unmatched by federal funds. Thus, federal interest in the project is a key factor in identifying priority projects for funding. Projects conducted with funds entirely supplied by other federal agencies, such as the Department of Defense Environmental Contamination program, are closely linked to the needs of the funding source. This program is administered at the district level. Often there is little flexibility within individual projects which must complete the tasks agreed to within the agreed upon time frame. However, it has been the USGS experience that, these projects can evolve into challenging areal hydrologic assessments. There is little opportunity for processoriented research within this program, but there is much opportunity to field test methods and techniques, to demonstrate new study approaches, and to apply the scientific understanding obtained from the Core Hydrologic Research program and the Toxic Substances Hydrology program. Because growth of this program is primarily limited by the availability of personnel, the USGS has the opportunity to choose offers which are

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most challenging and which will provide opportunities to further the general understanding of contaminant hydrology. Program Development and Interaction The mix of projects within the four programs provides a variety of activities related to hazardous materials science. The Core Hydrologic Research program and Toxic Substances Hydrology program provide continuity, longterm investigations, and the opportunity for development of methods and tools. At the other end of the spectrum, the Federal-State Cooperative program and projects funded by other federal agencies keep the USGS in touch with realworld problems and help to identify emerging issues. The balance of effort within programs and among programs is periodically adjusted to meet new challenges and to maintain an overall effort that provides understanding for the present and the future, as well as the capability for action at specific problem sites. The success of the USGS Hazardous Materials Science program is judged by its relevance and usefulness to the scientific community and to decision makers. The Core Hydrologic Research program has the longest time horizon; here exists the opportunity to fund scientific investigations that may have payoff years into the future. For example, scientists funded by this program were instrumental in developing the basic understanding of ground water hydrology that was fundamental for the development and application of ground water flow and transport models. Today, these models are used world-wide by the USGS and the academic and consulting communities, in studies of hazardous waste sites. Other tools developed under the Core Hydrologic Research program that are currently in widespread use or are emerging technologies include geochemical models and the use of chloroflourocarbon compounds for agedating ground water. Although there is a component of undirected, long-term research within the Toxic Substances Hydrology program, most projects are more problemoriented and of intermediate duration (4-10 years). The focus on interdisciplinary research at field sites known to be contaminated has allowed USGS to produce important understanding of contaminant trans

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port and transformation mechanisms. This understanding and the study approaches used by the program have been adapted for use within USGS operational programs. For example, natural biodegradation of organic contaminants in ground water, as demonstrated at the Bemidji and Galloway field sites, is starting to be considered as a remediation alternative. Projects funded by the Federal-State Cooperative program and the Department of Defense are gathering data related to this process and evaluating their importance at contaminated ground water sites. The Federal-State Cooperative program and the Department of Defense Environmental Contamination program provide an important feedback mechanism to USGS research and methods development programs. First, it is through these programs that new research methods are applied to help solve problems. Second, these operational programs have, over the years, identified problems that have required increased attention from the research community. For example, in the 1970's, projects within the Federal-State Cooperative program and meetings with local cooperators, as well as other sources of information, helped to identify the emerging problem of organic contaminants in ground water. The USGS responded to the general problem of ground water contamination by developing new procedures for sample collection, new analytical methodology in the laboratory, and new approaches to understanding ground water transport of organic contaminants. Further, concern about hazardous contaminants in water resources led to the initiation of the Toxic Substances Hydrology program. CORE HYDROLOGIC RESEARCH PROGRAM PLANNING AND DECISION-MAKING PROCESS Origin The Core Hydrologic Research program is an important source of funding for the National Research Program (NRP), which had its beginnings in the late 1950's when core research was added as a line item to the Congressional budget. Since that time, the NRP has grown to encompass a broad spectrum of scientific investigations, and the source of funding for the NRP has expanded to include several other USGS

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programs and other federal agencies. Because the planning process for Core Hydrologic Research program funds is included within the overall NRP planning process, the remainder of this section will focus on the plans and decision-making process of the NRP. The NRP uses the sciences of hydrology, mathematics, chemistry, physics, ecology, biology, geology, and engineering to gain a fundamental understanding of the processes that affect the availability, movement, and quality of the nation's water resources. The knowledge gained and methods developed have great value to WRD's operational program. Results of the investigations conducted by the NRP are applicable not only to the solution of current water problems, but also to future issues that may affect the nation's water resources. Plans for Program Development The NRP conducts basic and problem-oriented research in support of the mission of the USGS. Relevant hydrologic information provided by the USGS is available today to assist the nation in solving its water problems because of a conscious decision made in years past to invest in research. The NRP is designed to encourage pursuit of a diverse agenda of research topics aimed at providing new knowledge and insights into varied and complex hydrologic processes that are not well understood. The emphasis of these research activities changes through time, reflecting the emergence of promising new areas of inquiry and the demand for new tools and techniques with which to address water resources issues. For example, the National Water Quality Assessment program was conceived by NRP researchers, and has now become one of the largest operational programs in WRD. Recently, a new technique using chloroflourocarbon compounds to date ground water was developed in the NRP and is being widely used in the operational program. Knowledge gained and methods developed in this program apply to all of the hydrologic investigations of the USGS, to the water-oriented investigations and operations of other agencies, and to the general scientific community. Through the years, many of the USGS's major research and resource assessment initiatives related to existing and emerging national water resources problems had their origins in the NRP.

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Decision-making Process The activities of the NRP are divided into six research disciplines: Ground Water Chemistry; Surface Water Chemistry; Ground Water Hydrology; Surface Water Hydrology; Geomorphology and Sediment Transport; and Ecology. Activities in each discipline are conducted by project chiefs, and the general focus of, and guidance within, a discipline is provided by a Research Adviser (RA) and Assistant Research Adviser (ARA) for that discipline. Individual researchers within the NRP operate with a high degree of independence in terms of choosing a research problem and in carrying out research on that problem. The results of the research are published in peer-reviewed journals, as USGS publications, or sometimes both. In this way, the information gained in the studies is widely disseminated within the agency and to the scientific community at large. In addition, researchers in the NRP generally spend up to 30 percent of their time consulting with District personnel on specific problems, the approaches needed to solve those problems, and new methods and techniques useful to District projects. Researchers in the NRP are evaluated every three years (or more often if desired) by a panel of peers. The evaluation, based on material supplied by the researcher, prepared according to a standard format, considers the researchers achievements, publications, service to the organization, and other factors. Promotions and other personnel actions are based on the recommendation of the peer panel. Once a year, a meeting of the NRP Research Committee is held. The committee consists of: Assistant Chief Hydrologist for Research and External Coordination (ACH/R&EC); Assistant Chief Hydrologist for Program Coordination and Technical Support; Chief, Office of Hydrologic Research (OHR); Chief, Office of Ground Water; Chief, Office of Surface Water; Chief, Office of Water Quality; RAs, and ARAs. At this meeting, the NRP program is reviewed, strengths and weaknesses are identified, and recommendations are made for program direction and priority areas for new hires. In order to continue to foster effective and productive scientific research programs, managers of the USGS WRD require ongoing assessments of the quality of research being conducted. An important part of this assessment procedure is a periodic review of research activities and

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accomplishments within related "subdiscipline" groups (clusters) of WRD research projects by panels of respected researchers from both inside and outside of the USGS. The primary purposes of the cluster reviews are to provide managers with expert opinion concerning WRD research activities and to provide the research staff with an evaluation of the direction, techniques, and perceived impact of their research. The goal of the cluster review is to improve future research within subdiscipline groups (clusters). Once a year, an NRP budget meeting is held. At this meeting, the ACH/ R&EC; Chief, OHR; Chief, Branch of Regional Research (BRR), Eastern Region; Chief, BRR, Central Region; Chief, BRR, Western Region; RAs, and ARAs review each of the projects in the NRP and their requested budgets for the next fiscal year. Productive projects addressing high priority issues are treated most favorably. Funding restraints may be used to encourage changes in less productive projects and those addressing lower priority issues. In this manner, the budgetary process provides one method of directing reorientation of the focus and productivity of projects. USGS TOXIC SUBSTANCES HYDROLOGY PROGRAM PLANNING AND DECISION-MAKING PROCESS Origin The USGS Toxic Substances Hydrology (Toxics) program began in 1983 as an outgrowth of a then-existing program on Subsurface Waste Injection. From 1983 until 1985, the program addressed only ground water contamination. In 1986, a surface water component was added. The driving force for the creation and continuation of the program is the fact that it will take enormous financial resources to clean up hazardous waste sites in this country and to reduce contamination from nonpoint sources. The objective of the program is to provide information that is useful in making decisions about remediation of existing contaminated areas and the prevention of future contamination.

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Plans for Program Development Focused field investigations are conducted at sites that are known to be contaminated. The goal of these intensive investigations is to obtain a better understanding of the processes that control contaminant transport and transformation. Obtaining information that is transferable to other sites is a factor in selecting sites and planning investigations. The goal of the program is to address major sources and types of contamination of ground water and surface water. A decision was made early in the program that USGS could make an important contribution by conducting, long-term research at wellcharacterized sites. Thus, assessments of sites continue to be funded as long as they are productive. The program's budget has been stable for several years; therefore, new investigations can only begin when ongoing studies are completed and funds can be redirected. Original plans for the program were to gain additional insights into controlling processes by conducting comparison studies of the same contaminants in different climatic and geographic regions. For example, gasoline in ground water would be investigated in the humid northeast and in the and west, and pulp mills discharging to rivers in Florida and in Oregon would be studied. This overall plan has not been followed because of financial and human resource limitations. Duplication of studies in different climatic regions has been judged to be less important than addressing a number of the most important types and sources of contamination at least once. In the early years of the program, 14 studies of nonpoint source and ground water contamination were funded. Seven of these studies were continued through the late 1980's to allow for more extensive data analysis. The overall goal of all of these studies was to understand the relationship between ground water quality and land use and natural factors. In 1989, the program began a series of studies of the occurrence of agricultural chemicals (pesticides and nitrate) in water resources of the upper Midwestern cornbelt. These studies have been highly coordinated with the U.S. Department of Agriculture (USDA) and the U.S. Environmental Protection Agency (USEPA).

SW, San Francisco Bay and tributaries, CA GW & SW, Norman landfill, OK

nutrients, trace metals

organic chemicals

arsenic

organic chemicals

trace metals

copper, trace metals

trichloroethylene

gasoline

pesticides, trace metals, organic chemicals

mixture of inorganic and organic contaminants

Sewage disposal

Crude oil

Gold-ore processing

Petrochemical industry

Mining

Copper-ore processing

De-greasing operation

Leaking storage tank

Agriculture and urban land use

Landfill

GW, Galloway, NJ

GW, Picatinny Arsenal, NJ

GW & SW, Globe, AZ

SW, Arkansas River, CO

SW, Calcasieu River, LA

SW, Whitewood Creek, SD

GW, Bemidji, MN

GW, Cape Cod, MA

GW, Pensacola, FL

creosote

Wood treatment

Environment

Contaminants

Source

The Toxics program has investigated the following major sources and types of contamination:

initiated FY 1994

ongoing

ongoing

report writing

ongoing

ongoing

finished

finished

ongoing

ongoing

finished

Status

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Decision-making Process Decisions about the nonpoint source investigations are discussed above. The most recent focus for that component of the program, the upper Midwest, was chosen after consultation with USDA and USEPA. New directions within the field-oriented investigations are established by the selection of new sites for study of specific types of contaminants. The process for selecting sites for new focused field investigations is a follows: 1. Regional, District, and research offices are contacted to gain insight into the sources of contamination, types of contaminants, or hydrogeologic environments that are in need of investigation by the Toxics program. The intent is to provide understanding, methods, and study approaches for use in the USGS operational program. Because personnel in the USGS operational program have frequent contact with state agencies and EPA regional offices, they are an excellent source of information about emerging national issues. 2. A call for site nominations is distributed. 3. An interdisciplinary team of USGS experts is assembled to review site nomination packages and provide advice about which sites offer the best opportunities. 4. The research team for the selected site prepares a 3- or 4-year integrated research plan which will guide activity at the site. The site-selection team provides some advice about the kinds of issues that need to be clarified during preparation of the research plan. 5. After the integrated research plan is prepared, it is reviewed by several members of the site-selection team. Comments and suggestions are forwarded to the site team. Modifications to the research plan are made, as necessary. 6. Progress of the site investigations is determined on a continuing basis through review of publications from the studies. A more complete review occurs every 2 and one-half years at technical meetings of the Toxics program. At the end of the 3- or 4-year research cycle, the site research teams are asked to prepare a plan for continuation of research. This is reviewed by program coordinators and technical advisors to deter

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mine relevance, quality of science, and past productivity. Decisions about closing out projects are based on this technical review. FEDERAL-STATE COOPERATIVE PROGRAM PLANNING AND DECISION-MAKING PROCESS Origin The USGS Federal-State Cooperative Program has contributed directly to water resources knowledge for almost 100 years. The first USGS cooperative water resources investigation was with the State of Kansas in 1895. In 1905, Congress appropriated funds specifically for cooperative studies, marking the official beginning of the program. In 1928, Congress gave formal recognition to the federal-state partnership and limited the Federal financial contribution for cooperative water resources studies to no more than 50 percent of the total funds for each investigation. In 1977, Congress recognized the need for uniform, current, and reliable information on water use and directed the USGS to establish a National Water-Use Information Program, which is similar to the Federal-State Cooperative Program. The data collected and compiled on the nation's water use complements the USGS data on the availability and quality of the nation's water resources. The fundamental characteristic of the Federal-State Cooperative Program is that local and state agencies provide at least one-half the funds to the USGS and the USGS does most of the work. The Federal-State Cooperative Program contributes directly to water resources knowledge by fostering a working partnership between the federal and state and local governments in the advancement of earth science, and by compiling a major part of the nation's hydrologic information. From its earliest days, the program has been responsible directly for the development of procedures for streamgaging, concepts of surface water and ground water flow, and analytical techniques for investigations of water quality.

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Plans for Program Development In fulfilling its water resources mission, the USGS performs four principal functions: • It collects data needed for the continuing determination and evaluation of the quantity, quality, and use of the nation's water resources. • It conducts analytical and interpretive appraisals to describe the occurrence, availability, and physical, chemical, and biological characteristics of surface and ground water. • It conducts research in hydraulics, hydrology, and related scientific and engineering fields. • It disseminates water data and the results of investigations and research. The collection of surface water and ground water data on a systematic basis under the provisions of the Federal-State Cooperative Program is a major part of the USGS's coordinated water resources activities. The resulting information provides a continuing record of the quantity, quality, and use of the nation's water resources. These data provide information necessary for the determination of water suitability for various uses, identification of trends, and evaluation of the effects of stresses on the nation's surface and ground water resources. Within the Federal-State Cooperative Program, typically about half of the funds support the collection of hydrologic data; the remaining half support hydrologic investigations and research. Investigations encompass areas that range in size from a square mile or less to multistate regions. In these investigations, USGS scientists bring together information to define, characterize, and evaluate the areal extent, quality, and availability of the water resource. Since the early 1970's, there has been an increase in the number of investigations that have emphasized water quality issues, such as aquifer contamination, river quality, storm runoff quality, and the effects of acid rain, coal mining, and agricultural chemicals and practices on the hydrologic system. All data and results of analytical studies are made available to cooperating agencies and to the public through published reports and

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through computerized information programs, such as the National Water Information System (NWIS) and the National Water Data Exchange (NAWDEX) Program. Abstracts of completed reports are made available through the USGS Water Resources Scientific Information Center (WRSIC). Hydrologic data can be accessed by computer terminals at offices in every state. In many places, the Federal-State Cooperative Program provides the only source of support for water data collection and investigations required to assess, on a continuing basis, the status of the nation's water resources. Information developed in the Federal-State Cooperative Program has relevance to potential and emerging long-term problems, such as water supply, waste disposal, energy development, and environmental management and protection. Because common analytical methods and techniques are used, the information also is relevant to problems having interstate, regional, national, or international significance. The program provides the basis required to abide by interstate and international compacts and federal law and court decrees, and to carry out congressionally mandated studies, regional and national water resources assessments, and planning activities. Decision-making Process Program priorities are based on national needs that have been identified by the President and Administration advisors, by the Congress, by the Department of the Interior, by other federal agencies, and from information the USGS has received from cooperating agencies and other interested parties. Issues that are identified through the National Water Summary preparation process also are taken into consideration. As a result, the priorities are developed in response to mutual federal, regional, state, and local requirements. The USGS and its cooperating agencies work together in a continuing process that leads to adjustments in the program each year. The number of requests for scientific and technical assistance continues to grow from state agencies responsible for ground water protection and for controlling and mitigating contamination. State offerings typically exceed federal matching funds each year and reflect the increasing emphasis on water

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quality issues, as well as other concerns regarding the availability, distribution, and use of the resource. Each year, about $1.0 million in federal funds from the Federal-State Cooperative Program allocation are set aside for merit competition. Project proposals are reviewed by USGS peer panels and those with highest scientific merit are selected to receive the federal merit funds. The other half of the funds for these projects are provided by state or local cooperators. This process, which directs federal matching funds to the best proposals, assures that the FederalState Cooperative Program will continue to provide relevant and high-quality information. DEPARTMENT OF DEFENSE ENVIRONMENTAL CONTAMINATION HYDROLOGY PROGRAM–PLANNING AND DECISION-MAKING PROCESS Origin The USGS Department of Defense (DOD) Environmental Contamination Hydrology Program became an official WRD program in 1987 when a manager was named to the program at WRD headquarters. Until that time the program consisted of a loose network of a few studies throughout the WRD. The objective of the program is to provide technical expertise to the DOD while simultaneously providing a forum for furthering WRD's understanding of the processes related to the fate and transport of environmental contaminants in ground water, surface water, and aquifer material. Plans for Program Development The program is developed by responding to the requests by DOD agencies to WRD headquarters and District offices. Agreements have been developed and are in the process of being developed with numerous DOD agencies. These agreements list WRD's interests and capabilities. DOD partners communicate directly with WRD District offices identified by the Program Manager as the appropriate partnering WRD office. The

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program is developed at the District level where studies are undertaken within the District's capabilities and limitations. Current investigations address the following aspects of contaminant hydrology: • • • • • • • • •

Definition of hydrogeologic framework of many terranes. Movement of ground water and contaminants in different terranes. Ground water flow modeling of different terranes. Heavy metals in ground water. Isotope geochemistry. Surface and borehole geophysics. Soil gas and its relation to ground water contamination. Determination of aquifer parameters of different terranes. Development of relational data base and use of geographic information systems. • Bioremediation of contaminants in different hydrogeologic environments. • Quality assurance and quality control of laboratory analytical data and field data. Decision-making Process

DOD commands contact the program manager who in turn contacts the Regional Hydrologist's representative in the affected region. The decision to undertake a DOD-funded project lies with the District Chief in consultation with the pertinent Regional Hydrologist. In some cases a DOD partner may request that WRD undertake a program consisting of many studies located throughout the country under the condition that WRD agree to work at some or all of the sites. In these cases the decision on any study remains with the District Chief in consultation with the Regional Hydrologist. Decisions to undertake these environmental studies are made when the process of conducting the investigation provides the WRD with opportunities to further advance its understanding of the processes related to the fate and transport of environmental contaminants in ground water, surface water, and aquifer material.

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SUMMARY In summary, USGS projects in hazardous materials science span a spectrum of hydrologic investigations. Collectively, the Core Hydrologic Research program, the Toxic Substances Hydrology program, the Federal-State Cooperative program, and the Department of Defense Environmental Contamination program allow the USGS to maintain the capability to undertake process-oriented research, conduct developmental activities, and address realworld problems. Each program has a planning and decision-making process that meets individual program needs as determined by program objectives. Balance and feedback among programs keep the USGS effort at the cutting-edge of science and relevant to policy makers and resource managers.

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Appendix B Biographical Sketches of Committee Members GEORGE M. HORNBERGER obtained his Ph.D. from Stanford University (hydrology) in 1970. He also holds a bachelor's (1965) and a master's (1967) degree in civil engineering from Drexel University. As a professor at the University of Virginia, he is currently interested in modeling of environmental systems with uncertainty, hydrogeochemical response of small catchments, and transport of bacteria in porous media. Dr. Hornberger is a member of the National Academy of Engineering. LISA ALVAREZ-COHEN is an Assistant Professor in the Department of Civil Engineering at the University of California, Berkeley, where she teaches classes on Hazardous and Industrial Waste Treatment Process and Environmental Microbiology. She received her Ph.D. in Environmental Engineering and Sciences from Stanford University. Dr. Alvarez-Cohen's research interest include experimental research and modeling of microbial processes in porous media, bioremediation of contaminated aquifers, innovative hazardous waste treatment technologies, and application of cometabolic biotransformation reactions. KENNEYH R. BRADBURY is a research hydrogeologist/professor with the Wisconsin Geological and Natural History Survey, University of WisconsinExtension, in Madison, Wisconsin. He received his Ph.D. (hydrogeology, 1982) from the University of Wisconsin-Madison, his A.M. (geology, 1977) from Indiana University, and his B.A. (geology, 1974) from Ohio Wesleyan University. His current research interests

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include ground water flow in fractured media, ground water recharge processes, wellhead protection, and the hydrogeology of glacial deposits. CONSTANCE HUNT received her BS in wildlife biology from Arizona State University, and her MA in public policy from the University of Chicago. She is a senior program officer with the World Wildlife Fund, where she directs the freshwater ecosystem conservation program, including projects to promote restoration of the upper Mississippi River basin, coordination with South Florida restoration efforts, involvement in national water resources policy, and international river conservation efforts. Previously, she conducted inter-agency coordinator projects, wetland evaluations and delineations, permit processing, and environmental impact analysis while on the staff of the U.S. Environmental Protection Agency and the U.S. Army Corps of Engineers. DAWN S. KABACK is a hydrogeochemist who received her Ph.D. in geological sciences from the University of Colorado in 1977. Presently, she is Interim Director of the Colorado Center for Environmental Management in Denver. Until recently, Dr. Kaback managed the ground water research group (Environmental Sciences Section) at the DOE Savannah River Laboratory in Aiken, South Carolina. Her work involves aquifer characterization and development of innovative technologies to improve environmental restoration of contaminated soils and ground water. Previously, she worked for Conoco in the R&D department where she had a variety of assignments related to environmental effects of mining, geochemical exploration, and clastic diagenesis as applied to petroleum exploration. DAVID H. MOREAU is director, Water Resources Research Institute of the University of North Carolina and also professor in the departments of City and Regional Planning and Environmental Sciences and Engineering. Dr. Moreau received a B.Sc. (civil engineering, 1960) from Mississippi State University, a M.Sc. (civil engineering, 1963) from North Carolina State University, a M.Sc. (engineering, 1964) from Harvard University, and a Ph.D. (water resources, 1967) from Harvard University. Dr. Moreau has been a consultant to United Nations Development Program, Water Management Models for Water Supply; New

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York City, review of water demand projections; and Water for Sanitation and Health Program (AID), financing of water supply and waste disposal. FREDERICK G. POHLAND is Professor and Edward R. Weidlein Chair of environmental engineering, Department of Civil and Environmental Engineering, University of Pittsburgh. He received his Ph.D. in civil engineering from Purdue University in 1961. Dr. Pohland research interests include environmental engineering operations and processes; water and waste chemistry and microbiology; solid and hazardous waste management; and environmental impact monitoring assessment and remediation. Dr. Pohland is a member of the National Academy of Engineering. FRANK W. SCHWARTZ received his Ph.D. in geology in 1972 from the University of Illinois. He is currently Ohio Eminent Scholar in Hydrogeology at Ohio State University. Dr. Schwartz has been an active consultant to government and private industry since 1972. Most of his work has involved project management, report review, technical advice, the development and application of computer models, and field investigations. Dr. Schwartz is a member of the Water Science and Technology Board. LEONARD SHABMAN received a Ph.D. in agricultural economics in 1972 from Cornell University. He is a professor at Virginia Polytechnic Institute, Department of Agricultural Economics. Dr. Shabman has conducted economic research over a wide range of topics in natural resource and environmental policy, with emphasis in 6 general areas: coastal resources management; planning, investment, and financing of water resource development; flood hazard management; federal and state water planning; water quality management, and fisheries management. MITCHELL J. SMALL a professor at the Carnegie Mellon University, in the Civil and Environmental Engineering and Engineering and Public Policy Departments. He received his M.S. and Ph.D. from the University of Michigan. Dr. Small, has interests in mathematical modeling of environmental quality; statistical methods and uncertainty analysis; human risk perception and decision making.

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ALAN T. STONE received his B.S. in chemistry from the University of Maryland-College Park in 1978, his M.S. in 1981 and Ph.D. in 1983 in environmental engineering from the California Institute of Technology. He is currently a professor in the Department of Geography and Environmental Engineering at Johns Hopkins University. His research interests are in the area of chemical kinetics and mechanisms; reactions at surfaces; abiotic degradation of organic pollutants; redox reactions; precipitation and dissolution of minerals, environmental chemistry of soils, sediments, and aquifers. DAVID A. WOOLHISER received his Ph.D. in Civil Engineering, with minors in Meteorology and Geophysics, from the University of Wisconsin in 1962. Dr. Woolhiser retired from the USDA Agricultural Research Service in 1991 after a 30 year career and is currently a Faculty Affiliate in civil engineering at Colorado State University and a hydrologist in Fort Collins, Colorado. He is known for his work on the hydrology and hydrometerology of arid and semiarid rangelands, simulation of hydrologic systems, numerical modeling of surface runoff, erosion and chemical transport, and probabilistic models of rainfall and runoff. He is a member of the National Academy of Engineering.