[en] This report documents the Feasibility Study (FS) phase of the Fernald Environmental Management Project (FEMP) Operable Unit 4 Remedial Investigation/Feasibility Study (RI/FS) Program. The FEMP, formerly known as the Feed Materials Production Center (FMPC), is a US Department of Energy (DOE) facility that operated from 1952 to 1989. The facility's primarily function was to provide high purity uranium metal products to support United States defense programs. Production operations were suspended in 1989 to focus on environmental restoration and waste management activities at the facility. The RI/FS is being conducted pursuant to the terms of a Consent Agreement between DOE and the US Environmental Protection Agency (EPA) under Sections 120 and 106(a) of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), as amended. The Ohio Environmental Protection Agency (OEPA) is also participating in the RI/FS process at the FEMP through direct involvement in program review meetings and technical review of project documentation. The objective of the RI/FS process is to gather information to support an informed risk management decision regarding which remedy appears to be the most appropriate action for addressing the environmental concerns identified at the FEMP. This volume contains appendices F--J