This document addresses the factors that have been found to be relevant for successfully implementing PRBs for contaminant remediation. Additionally, it provides sufficient background in the science of PRB technology to allow a basic understanding of the chemical reactions proposed for the contaminant transformations that have been witnessed both in the laboratory and in field settings. It contains sections on PRB-treatable contaminants and the treatment reaction mechanisms, feasibility studies for PRB implementation, site characterization for PRBs, PRB design, PRB emplacement, monitoring for both compliance and performance, and summaries of several field installations. The appendices supplement this information with a detailed table of information available in the literature through 1997, summarizing the significant findings of PRB research and field studies (Appendix A), a further examination of the physical and chemical processes important to PRBs, such as corrosion, adsorption, and precipitation (Appendix B), and a set of scoping calculations that can be used to estimate the amount of reactive media required and facilitate choosing among te possible means of emplacing the required amount of media (Appendix C). Appendix D provides a list of acronyms and Appendix E a glossary of terms that are used within this document.