[en] This Proposed Plan identifies the preferred alternative for interim remedial measures for remedial action of radioactive liquid waste disposal sites that include contaminated soils and structures at the 100-BC-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 pose potential threats to human health and the environment. The preferred alternative presented in this Proposed Plan is to remove, treat as appropriate or required, and dispose of the contaminated soil and associated structures from nine source areas within the 100-BC-1 Operable Unit. Treatment would be conducted as necessary or appropriate for cost effective operations. The preferred alternative will reduce potential threats to human health and the environment at 100-BC-1 Operable Unit radioactive liquid waste disposal sites. The remedial actions described are intended to reduce potential human health and ecological risks and to ensure that contaminants present at these waste sites will not adversely impact groundwater beneath the sites or the Columbia River