Conceptual Site Model - Argonne National Laboratory

WVDP Phase 1 CSAParranged on a triangular grid with a 20-m grid spacing will be used to evaluate thecontamination status of the top 1m of soil. Approximately 15 sampling locations will berequired. Each location will have one sample collected to a depth of 1 m. In addition,each will have a down-hole gross activity scan with one measurement taken each 15 cm.[required]A.9.4Subsurface Soil SamplingSubsurface soil sampling within WMA 1 has three purposes: (1) to determine presence andvertical extent of contamination impacts above background levels for WMA 1 areas along theedge of and outside the planned deep excavation, (2) to estimate waste stream volumes in supportof the planned WMA 1 deep excavation, and (3) to provide geotechnical and contamination statusinformation for the footprints of the slurry and sheet walls.• WMA 1 Waste Characterization. Subsurface soil cores will be obtained within thefootprint of the planned WMA 1 excavation to address contaminated soil volumeestimation needs. Of the three acre excavation footprint, only approximately 1.2 acreswould likely be readily accessible for intrusive subsurface sampling. This 1.2 acres isabout evenly divided between the western edge of the excavation, the northeastern cornerof the excavation, and the southeastern corner of the excavation. Sixteen core locationswill be placed within these accessible areas to a depth of 1 m into the Lavery Till. Thecores will be located to provide systematic coverage of the accessible areas(approximately one core per 300 m 2 ). Each one meter interval of each core will be subsampledin a fashion to obtain a representative sample, and those samples submitted forquick turn-around analysis of Sr-90 and Cs-137. With an average expected depth-to-tillof 35 feet, approximately 192 samples will be collected and analyzed. These data will beused to estimate waste stream volumes resulting from the excavation of WMA 1.[required]• Sheet Piling Footprint Characterization. Subsurface soil coring, scanning, andsampling will take place along the western and southern boundaries of the plannedexcavation, as well as the portions of the northern boundary associated with the sheetpiling footprint, to confirm the contamination status of adjacent surface and subsurfacesoils. An initial set of approximately 30 locations will be sampled; these locations will beRev. 1 A-16