Feasibility study report for the 200-BP-1 operable unit

This feasibility study (FS) examines a range of alternatives and provides recommendations for selecting a preferred altemative for remediating contamination at the 200-BP-1 operable unit. The 200-BP-1 operable unit is located in the center of the Hanford Site along the northern boundary of the 200 East Area. The 241-BY Tank Farm is located immediately to the south of the operable unit. 200-BP-1 is a source operable unit with contaminated soils associated primarily with nine inactive cribs (known as the 216-B cribs). These cribs were used for disposal of low-level radioactive liquid waste from U Plant uranium recovery operations, and waste storage tank condensate from the adjacent 241-BY Tank Farm. The cribs used for disposal of U Plant waste were in operation from 1955--1965, and the cribs used for disposal of tank condensate were in operation from 1965-1975. In addition to the cribs, four unplanned releases of radioactive materials have occurred within the operable unit. Contaminated surface soils associated with the unplanned releases have been consolidated over the cribs and covered with clean soil to reduce contaminant migration and exposure. Discharge of wastes to the cribs has resulted in soil and groundwater contamination. The groundwater is being addressed as part of the 200 East Aggregate Area groundwater operable unit. Contaminated soils at the site can be categorized by the types of contaminants, their distribution in the soil column, and the risk posed by the various potential exposure pathways. Below the clean soil cover, the near surface soils contain low-:levels of contamination with cesium-137, radium-226, strontium-90, thorium-228 and uranium. The lifetime incremental cancer risk associated with these soils if they were exposed at the surface is 9 x 105