[en] This proposed plan identifies the preferred alternative for interim remedial measures for remedial action of radioactive liquid waste disposal sites at the 100-HR-1 Operable Unit, located at the Hanford Site. It also summarizes other remedial alternatives evaluated for interim remedial measures in this operable unit. The intent of interim remedial measures is to speed up actions to address contaminated areas that historically received radioactive liquid waste discharges that pose a potential threat to human health and the environment. This proposed plan is being issued by the Washington State Department of Ecology (Ecology), the lead regulatory agency; the US Environmental Protection Agency (EPA), the support regulatory agency; and the US Department of Energy (DOE), the responsible agency. Ecology, EPA, and DOE are issuing this proposed plan as part of their public participation responsibilities under Section 117(a) of the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA), commonly known as the ''Superfund Program.'' The proposed plan is intended to be a fact sheet for public review that (1) briefly describes the remedial alternatives analyzed; (2) proposes a preferred alternative; (3) summarizes the information relied upon to recommend the preferred alternative; and (4) provides a basis for an interim action record of decision (ROD). The preferred alternative presented in this proposed plan is removal, treatment (as appropriate), and disposal of contaminated soil and associated structures. Treatment will be conducted if there is cost benefit