Successful Implementation of Soil Segregation Technology at the Painesville FUSRAP Site - 12281
Typically the highest cost component of the radiological soils remediation of Formerly Utilized Sites Remedial Action Program (FUSRAP) sites is the cost to transport and dispose of the excavated soils, typically contaminated with naturally occurring isotopes of uranium, thorium and radium, at an appropriately permitted off-site disposal facility. The heterogeneous nature of the contamination encountered at these sites makes it difficult to accurately delineate the extent of contaminated soil using the limited, discrete sampling data collected during the investigation phases; and difficult to precisely excavate only the contaminated soil that is above the established cleanup limits using standard in-field scanning and guiding methodologies. This usually results in a conservative guided excavation to ensure cleanup criteria are met, with the attendant transportation and disposal costs for the larger volumes of soil excavated. To address this issue during the remediation of the Painesville FUSRAP Site, located in Painesville, Ohio, the Buffalo District of the U.S. Army Corps of Engineers, and its contractor, Safety and Ecology Corporation (SEC), employed automatic soil segregation technology provided by MACTEC (now AMEC) to reduce the potential for transportation and disposal of soils that met the cleanup limits. This waste minimization technology utilized gamma spectroscopy of conveyor-fed soils to automatically segregate the material into above and below criteria discharge piles. Use of the soil segregation system resulted in cost savings through the significant reduction of the volume of excavated soil that required off-site transportation and disposal, and the reduction of the amount of imported clean backfill required via reuse of 'below criteria' segregated soil as place back material in restoring the excavations. Measurements taken by the soil segregation system, as well as results of quality control sampling of segregated soils, confirmed that soils segregated as below criteria for reuse as site fill did meet the Record of Decision cleanup criteria for the site. Automatic soil segregation technology was successfully implemented as part of the 2010 - 2011 remediation effort at the Painesville FUSRAP Site. The Orion ScanSortSM system employed at the site demonstrated the ability to accurately determine the radioactivity concentrations in the processed soil and soil-like material and quickly segregate that material for appropriate final disposition. Data from the soil segregation system and confirmatory QC samples indicated that the segregated 'below criteria' soils met the cleanup criteria in the ROD, and was appropriate for reuse as fill in the excavations. The reduction of the total excavated soil volume requiring off-site disposal by 94% yielded significant project cost savings through reduction of transportation and disposal and backfill procurement costs. Use of automatic soil segregation technology was an efficient and cost-effective method for addressing the radiological contamination at the Painesville Site. (authors)