This Remedial Investigation and Feasibility Study Report for the Site-Wide Waste Disposition Evaluation Project at the Portsmouth Gaseous Diffusion Plant, Piketon, Ohio, presents the information necessary to select a Site-wide disposal alternative for the waste generated under the Director’s Final Findings and Orders (DFF&O) for Removal Action and Remedial Investigation and Feasibility Study and Remedial Design and Remedial Action. This decision is designed to coincide closely with another major DFF&O decision, the fate of the majority of buildings at PORTS, which is evaluated in Remedial Investigation and Feasibility Study Report for the Process Buildings and Complex Facilities Decontamination and Decommissioning at the Portsmouth Gaseous Diffusion Plant, Piketon, Ohio. The information in the Site-wide Waste Disposition Evaluation Remedial Investigation/Feasibility Study supports three elements of decision making: (1) problem definition, (2) solution identification, and (3) solution evaluation.