Conceptual Site Model - Argonne National Laboratory

WVDP Phase 1 CSAPbore/core scan identifies an elevated zone not included in one of these three, themeter interval containing the elevated zone will be submitted for laboratoryradiological analysis. Towards the eastern end of the planned excavation, theoverlying sand/gravel unit may pinch out; in this case there may be less than foursamples submitted for analysis if the depth to till is less than four meters. [required]oFrom each location three groundwater samples will be collected: one from the watertable, one from immediately above the Lavery Till, and one midway between thesetwo, if possible. In areas where the overlying sand/gravel unit pinches out, thenumber of groundwater samples may be reduced accordingly. [required]oIf any interval other than the top 1 m identifies contaminants above backgroundlevels, then additional soil core locations will be placed on a triangular grid with aseparation of 10 meters to the south of the location(s) of concern in a manner thatbounds the original contamination as the terrain allows and sampled as describedabove. This process will continue until the southern extent of subsurfacecontamination is bounded. If extensive subsurface contamination is encountered afield decision may be made to increase the separation distance between the originalset of core locations and the next set of bounding core locations. The ultimate intentis to spatially bound subsurface contamination to the south of the planned WMA 2excavation. This sampling may extend into WMA 12. [contingent]• Slurry Wall Footprint Characterization. Subsurface soil coring and scanning will takeplace following the planned slurry wall footprint along the western, northern, and easternportion of the WMA 2 excavation. These core locations will be separated by 20 m.Approximately 20 cores will be required. At each location, one core will be retrieved thatextends one meter into the Lavery Till. A down-hole scan will be conducted to the extentpossible at each location with a static measurement every 30 cm. Each core will bedivided into one meter segments.oSubsurface soil sampling, groundwater sampling, and core scanning protocols will bethe same for soil cores from the slurry wall footprints as for the southern boundary ofthe WMA 2 excavation. [required]Rev. 1 B-23