Conceptual Site Model - Argonne National Laboratory

WVDP Phase 1 CSAPdata collected to support the other goals will be used to explore the possibility of a surrogate ROI.Note that almost all CSAP soil samples will be analyzed for all 18 ROIs.6.4 Establish Background Data SetsThe Phase 1 DP presented background activity concentrations for surface and subsurface soilsbased on historical sampling. These background data are sufficient for establishing a generalsense of background activity concentrations for surface and subsurface soils for the 18 ROIs.However, they do not provide information regarding the background levels of the 12 potentialROIs, nor do they address the background level of gross activity that might be encountered duringsurface scans, nor do they establish a background data set sufficient for conducting statistical testssuch as the Wilcoxon Rank Sum (WRS) test that may be required by the Phase 1 FSS process.CSAP data collection will establish background values including both average conditions andbackground variability for gross gamma activity and for radionuclide-specific activityconcentrations for surface soils through the use of a reference area. Section 8 discusses theestablishment of a reference area and associated data collection in greater detail. Section 11.5provides details about protocols for establishing background gross gamma activities for surfacesoil scans.6.5 Determine Extent of Surface Soil ContaminationSurface contamination is defined as radionuclide contamination above background levels withinthe 0- to 1-m depth profile. In the case of surface soils covered with concrete slabs, pavement,asphalt, gravel, hardstand material, and the like, the start of the 0-to 1-m-depth profile is definedas the interface between the overlying cover material and the underlying soil surface. In the caseof areas where some surface soil removal is expected to take place as part of Phase 1 activities(outside of the WMA 1 and WMA 2 deep excavations), the start of the 0- to 1-m-depth profile isdefined as the exposed soil surface that remains after the initial removal has taken place. As anexample, when building slabs are removed, it is expected that as much as 60 cm of soilimmediately underlying the slab will be removed as well. In some cases, such as hardstands, theoverlying cover material may be more than 1-m thick. Phase 1 DP activities will remove existingcover material (building slabs, hardstands, and so on) in many of the WMAs.Rev. 1 29