126-F-1 radiological investigation and downposting. Final report

The 126-F-1 ashpit is located in the 100 F Area of the Hanford Site, in the 100-FR-2 operable unit. This waste site is managed under the Radiation Area Remedial Action (RARA) project. As such, the area has undergone routine surveillance which indicated that the site may have been improperly posted as a contamination area. The ashpit was the result of coal fired plant operations in the 100 F Area. Coal ash contains various amounts of fly ash, bottom ash, and boiler slag. From 1944 to 1971, reactor cooling water was discharged to the 107-F retention basins via an above grade pipe. This paper traversed the north edge of the 126-F-1 ash pit. Effluent leakage from the pipeline led to the formation of a pond north of the pipeline. In addition, effluent flowed south into the ashpit. Ultimately, the pipeline was removed. The area north of the pipeline was included inside the 100 F concrete marker posts and as such was posted as an underground radioactive material area. At a later unspecified date, the entire ashpit was posted ''Surface Contamination Area'', then later as a ''Contamination Area''. Routine surveys indicated that radioactive contamination levels were low. This report details efforts that lead to the downposting of the 126-F-1 ashpit from contamination area to no posting or underground radioactive material