[en] This proposed plan introduces the interim remedial measures for addressing contaminated soil at the 100-HR-1 Operable Unit, located at the Hanford Site. In addition, this plan includes a summary of other alternatives analyzed and considered for the 100-HR-1 Operable Unit. The EPA, DOE, and Washington State Dept. of Ecology believe that a combination of removal, treatment, and disposal technologies, where appropriate, would significantly reduce the potential threats to human health and the environment at the 100-HR-1 Operable Unit high-priority waste sites. The remedial actions described in this proposed plan are designed to minimize human health and ecological risks and ensure that additional contaminants originating from these waste sites are not transported to the groundwater. The 100-HR-1 Operable Unit contains the retention basin for the H reactor cooling system, process effluent trenches, the Pluto crib which received an estimated 260 gallons of radioactive liquid waste, process effluent pipelines, and solid waste sites used for the burial of decontaminated and decommissioned equipment from other facilities. Potential health threats would be from the isotopes of cesium, cobalt, europium, plutonium, and strontium, and from chromium, arsenic, lead, and chysene