In Situ Depth Profiling of CS-137 Contamination in Soils

Preremediation characterization of Cs-137 contamination in soils was conducted at the Auxiliary Reactor Area (ARA)-23 Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) site, located at the Idaho National Engineering and Environmental Laboratory. Characterization activities included verification of the lateral extent of the contaminated area using the INEEL Global Positioning Radiometric Scanner. The vertical extent of the contamination in select areas of the site also was evaluated with an in-situ gamma-ray spectrometer, and depth discrete samples were collected at 2-inch depth intervals down to a depth of 8 inches. A comparison was made between the depth distribution data from the in-situ spectrometric measurements and the physical, depth-discrete samples. The results of the study and of the aforementioned comparison indicate that use of in situ high purity germanium (HpGe) detectors during the remediation of the ARA-23 site will aid in directing the depth of excavation, thereby helping to (a) minimize the amount of soils excavated and removed for disposal, and (b) reduce overall project costs