Conceptual Site Model - Argonne National Laboratory

WVDP Phase 1 CSAPH.9.1 Gamma Walkover Survey DataThe purpose of performing a gamma walkover survey of the WMA 9 area is to identify the leveland extent of surface contamination. This includes both general trends in average activityconcentrations pertinent to the CG w requirement, as well as the identification of isolated, moreelevatedanomalies that might be indicative of discrete releases and/or CG emc concerns.A complete (100%) logged gamma walkover survey (GWS) will be conducted for accessibleareas within WMA 9. Examples of areas that would not be accessible are areas where standingwater is present in wetlands and the footprints of existing buildings. Based on the GWS results,surface soil within WMA 9 will be divided into four categories: (1) surface soils where GWS dataindicate contamination above CG w requirements; (2) surface soils where GWS data indicatecontamination, but it is not clear if contamination exceeds surface soil CG w requirement; (3)surface soils where GWS indicate impacts, but those impacts are not expected to exceed surfacesoil CG w standards; and (4) surface soils where there is no indication of impacts abovebackground conditions. The purpose of this data collection is to provide insights into the spatialdistribution of surface contamination, and to guide subsequent soil sampling. [required]H.9.2 Surface Soil SamplingSurface soil sampling will be used to address areas inaccessible to GWS data collection, toresolve hot spots identified by the GWS data, and to evaluate the presence, absence, and/or extentof surface contamination above CG w requirements based on GWS results.• Wetlands. It is possible that standing water will be present in wetlands that prevent GWSdata collection from those areas. The most likely place for this occurring is along thewestern bank of the railway line. Soil sampling will be required for wetland footprintsand for any other areas where standing water prevents the collection of GWS data.For every area where standing water or saturated soil conditions prevent GWS datacollection, systematic soil sampling will take place. At least one and at most fivesampling locations will be selected per area. One sample will be collected from eachlocation representative of a 0-15 cm depth interval. Locations will be selected to providesystematic coverage of the area of interest with a maximum sample density of one sampleRev. 1 H-6