Conceptual Site Model - Argonne National Laboratory

WVDP Phase 1 CSAP• CG w Sampling. Surface soil sampling may be conducted after the GWS to further clarifyresults, with the level and nature of sampling dependent on GWS results. If GWS resultsindicate no evidence of contamination impacts above background levels, no additionalsurface soil sampling will be required other than to address areas too wet to perform agamma walkover survey. Based on historical direct gamma measurements, the areas mostlikely to have contamination exceeding surface soil CG w requirements are along theboundary between WMA 6 and WMA 1.oIf GWS results indicate contamination impacts above background levels but thatsurface soil contaminant levels exceeding surface soil CG w requirements areunlikely, the area of interest will be systematically sampled using a triangulargrid with a density of one sample per 400 m 2 . One sample will be collected fromeach location representative of a 0-15 cm depth interval. Locations will beselected to provide systematic coverage of the area of interest. The purpose is todocument the activity concentrations present in surface soils within WMA 6.[contingent]oIf GWS results indicate surface soil contaminant levels exceeding surface soilCG w requirements likely exist, one sampling location will be selected at thehighest gross activity level to confirm surface soil CG w exceedances and anotherset of sampling locations will be identified to spatially bound the extent ofcontamination (i.e., along the boundary of what is considered likely abovesurface soil CG w requirements) if this is not obvious from the GWS data. Twosamples will be collected from the location targeting high gross activity levels,one representative of a 0-15 cm depth interval, and one representative of a15 cm-1 m depth interval. One sample will be collected from each locationintended to laterally bound contamination, representative of a 0-15 cm depthinterval. In addition, the location targeting high gross activity levels will haveone down-hole gamma scan conducted at the center of the location with staticmeasurements taken every 15 cm. The purpose is to document surface soil CG wrequirement exceedances and bound the lateral extent of contamination.[contingent]Rev. 1 F-14