Conceptual Site Model - Argonne National Laboratory

WVDP Phase 1 CSAP• If contamination above background is identified in one or more of these locations,additional locations may be selected further from the planned excavation footprint tobound the lateral extent of subsurface contamination (groundwater or soils) in the case ofsheet pile wall footprints and the southern boundary of the WMA 2 excavation. Theseparation distance from the excavation footprint will be a location-specific decision, andwill depend on the level of contamination encountered, the type of contamination (e.g.,groundwater versus soil), and the vertical extent of contamination observed. Bounding isnot required for the slurry wall footprints; the working assumption is that subsurface soilcontamination is present on the other side of slurry walls.• If buried infrastructure of potential concern is identified that intersects the planned WMA1 or WMA 2 excavation footprints, one of the trenches used to expose the buriedinfrastructure will be along the planned excavation boundary and evaluated for thepresence of adjacent soil contamination.6.9 Identify Soil Waste Stream CharacteristicsA significant volume of soil will be removed as part of the WMA 1 and WMA 2 excavations. Allexcavated soils will be disposed of off-site regardless of the soil activity concentrations. Theradionuclide activity concentrations of these soils are expected to vary widely, from non-affectedsoils, to low-level radionuclide contamination, to heavily contaminated soils. For planningpurposes, it is important to have estimates of the various soil waste streams that will be generatedby the WMA 1 and WMA 2 excavations.CSAP data collection will support the identification and estimation of contaminated waste streamtypes. Data collection will take the form of soil sampling from soil cores that are systematicallycollected across the accessible portions of the planned WMA 1 and WMA 2 excavations. Soilcores will be obtained that extend at least 1 m into the Lavery Till. Each soil core will be dividedinto 1-m intervals, with the final sample representing the top 1 m of Lavery Till and a samplefrom each interval submitted for analyses of Cs-137 and Sr-90. For example, if there were 10 soilcores to a total depth of 10 m, this would result in 100 samples. The sample with the highest Cs-137 activity concentration from each core will also be analyzed for the other 12 potential ROIs. .Rev. 1 43