Military geology comprises research and practical efforts directed toward providing geological input for military construction, civil works projects (e.g., dams, navigable waterway maintenance), remediation of polluted military facilities, terrain analysis, sustainability of training lands, mobility prediction, and site characterization activities. Land use sustainability issues, base closures, and heightened levels of environmental awareness by the general public have introduced new challenges for using, maintaining, cleaning, and restoring lands that have served as military installations for decades. In this volume, the legacy of military operations and their impact on the terrain and geology, particularly from an environmental viewpoint, are considered by geologists of diverse lands and backgrounds. This book, a companion volume to Military Geology in War and Peace (Reviews in Engineering Geology, v. 13, 1998), emphasizes current research and applications of engineering geology principles and practice to modern day military problems, many of which are environmental in nature.