Conceptual Site Model - Argonne National Laboratory

WVDP Phase 1 CSAPD.9 CSAP Pre-Remediation Data Collection and Associated Decision-MakingCSAP pre-remediation data collection will consist of a number of components described in moredetail below.D.9.1Gamma Walkover Survey DataThe purpose of performing a gamma walkover survey of the WMA 4 area is to identify the leveland extent of surface contamination. This includes both general trends in average activityconcentrations pertinent to the surface soil CG w requirement, as well as the identification ofisolated, more-elevated anomalies that might be indicative of discrete releases and/or surface soilCG emc concerns.A complete (100%) logged gamma walkover survey (GWS) will be conducted for accessibleareas within WMA 4. Examples of areas within WMA 4 that would not be accessible are areaswhere standing water is present in wetlands. Based on the GWS results, surface soil within WMA4 will be divided into four categories: (1) surface soils where GWS data indicate contaminationabove CG w requirements; (2) surface soils where GWS data indicate contamination, but it is notclear if contamination exceeds surface soil CG w requirement; (3) surface soils where GWSindicate impacts, but those impacts are not expected to exceed surface soil CG w standards; and (4)surface soils where there is no indication of impacts above background conditions. The purposeof this data collection is to provide insights into the spatial distribution of surface contamination,and to guide subsequent soil sampling. [required]D.9.2Surface 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 surface soil 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. Soil sampling will be required for wetland footprints andfor any other areas where standing water prevents the collection of GWS data. WithinRev. 1 D-8