This IMA Volume in Mathematics and its Applications RESOURCE RECOVERY, CONFINEMENT, AND REMEDIATION OF ENVIRONMENTAL HAZARDS contains papers presented at two successful one-week workshops: Confine ment and Remediation of Environmental Hazards held on January 15-19, 2000 and Resource Recovery, February 9-13, 2000. Both workshops were integral parts of the IMA annual program on Mathematics in Reactive Flow and Transport Phenomena, 1999-2000. We would like to thank John Chadam (University of Pittsburgh), Al Cunningham (Montana State Uni versity), Richard E. Ewing (Texas A&M University), Peter Ortoleva (In diana University), and Mary Fanett Wheeler (TICAM, The University of Texas at Austin) for their excellent work as organizers of the meetings and for editing the proceedings. We take this opportunity to thank the National Science Foundation for their support of the IMA. Series Editors Douglas N. Arnold, Director of the IMA Fadil Santosa, Deputy Director of the IMA v PREFACE Advances in resource recovery, and confinement/remediation of envi ronmental hazards requires a coordinated, interdisciplinary effort involving mathematicians, scientists and engineers. The intent of this collection of papers is to summarize recent theoretical, computational, and experimen tal advances in the theory of phenomena in porous media, with the intent to identify similarities and differences concerning applications related to both resource recovery and confinement and remediation of environmental hazards.

This volume is the Proceedings of the symposium held at the University of Wyoming in August, 1985, to honor Gail Young on his seventieth birthday (which actually took place on October 3, 1985) and on the occasion of his retirement. Nothing can seem more natural to a mathematician in this country than to honor Gail Young. Gail embodies all the qualities that a mathematician should possess. He is an active and effective research mathematician, having written over sixty pa pers in topology, n-dimensional analysis, complex variables, and "miscellanea." He is an outstanding expositor, as his fine book Topology, written with J. G. Hocking (Addison Wesley, 1961), amply demonstrates. He has a superlative record in public office of outstanding, unstinting service to the mathematical community and to the cause of education. But what makes Gail unique and special is that throughout all aspects of his distinguished career, he has emphasized human values in everything he has done. In touching the lives of so many of us, he has advanced the entire profession. Deservedly, he has innumerable friends in the mathematical community, the academic community, and beyond."

The need to predict, understand, and optimize complex physical and c- mical processes occurring in and around the earth, such as groundwater c- tamination, oil reservoir production, discovering new oil reserves, and ocean hydrodynamics, has been increasingly recognized. Despite their seemingly disparate natures, these geoscience problems have many common mathe- tical and computational characteristics. The techniques used to describe and study them are applicable across a broad range of areas. The study of the above problems through physical experiments, mat- matical theory, and computational techniques requires interdisciplinary col- boration between engineers, mathematicians, computational scientists, and other researchers working in industry, government laboratories, and univ- sities. By bringing together such researchers, meaningful progress can be made in predicting, understanding, and optimizing physical and chemical processes. The International Workshop on Fluid Flow and Transport in Porous - dia was successfully held in Beijing, China, August 2{6, 1999. The aim of this workshop was to bring together applied mathematicians, computational scientists, and engineers working actively in the mathematical and nume- cal treatment of ?uid ?ow and transport in porous media. A broad range of researchers presented papers and discussed both problems and current, state-of-the-art techniques.

This book describes in detail the current, state-of-the-art numerical treatment and simulation of multiphase flows in porous media. The porous media considered range from ordinary to fractured and deformable media, the models treated from single-phase compressible flow to multiphase multicomponent flow with mass interchange, while the computational algorithms encompass everything from classical iterative solvers to modern multigrid and domain decomposition approaches. Addressing many problems originating from the applied geosciences, the book focuses on their common mathematical and computational aspects. It will serve as an excellent research reference for all geoscientists, mathematicians, physicists, and engineers who work in the mathematical modeling and numerical simulation of multiphase flows in porous media.

The papers in this volume arose out of two workshops entitled "Confinement and Remediation of Environmental Hazards," and "Resource Recovery," as part of the IMA 1999-2000 program year. These workshops brought together mathematicians, engineers and scientists to summarize recent theoretical, computational, and experimental advances in the theory of phenomena in porous media. The first workshop focused on the mathematical problems which arise in groundwater transport of contamination, and the spreading, confinement and remediation of biological, chemical and radioactive waste. In the second conference, the processes underlying petroleum recovery and the geological time scale of deformation, flow and reaction in porous media were discussed. Simulation techniques were used to simulate complex domains with widely-ranging spatial resolution and types of physics. Probability funcional methods for determining the most probable state of the subsurface and related uncertainty were discussed. Practical examples included breakout from chemical and radioactive waste repositories, confinement by injection of pore plugging material and bioremediation of petroleum and other wastes. This volume will be of interest to subsurface science practitioners who would like a view of recent mathematical and experimental efforts to examine subsurface science phenomena related to resource recovery and remediation issues.