A four-volume report provides guidance to owners and operators of hazardous waste management facilities concerning the second phase of the EPA RCRA Corrective Action Program, viz., the RCRA Facility Investigation (RFI). Guidance is provided for conducting an RFI, based on pollutant release determinations made by the regulatory agency, covering soil, surface water, ground water, subsurface water, and air. Volume I covers the rationale, general strategy, and procedures for developing a plan for conducting an RFI, and describes how data collecting in an RFI will be interpreted by the regulatory agency; Volumes II and III describe media-specific methods for conducting an RFI; Volume IV presents case studies to illustrate various aspects of the RFI process.