Conceptual Site Model - Argonne National Laboratory

WVDP Phase 1 CSAPsouthern portion of WMA 4. In particular, significant ditch soil and sediment contaminationexists that exceeds Phase 1 surface soil CG w standards.Wastes placed in the CDDL were reportedly un-impacted by radionuclide contamination.However, given the fact that contaminated groundwater is moving through the contents of theCDDL, the working assumption is that currently CDDL contents likely have low-levelradioactive contamination present (DOE 2009 Section 2.4.3).Figure D.14 shows the current CSM for surface soils. Figure D.15 shows the CSM for soilsdeeper than 1 m. Subsurface soil contamination is assumed to be the result of and coincide withgroundwater contamination, although detectable groundwater contamination may exist in areaswhere soil contamination levels would not be detectable or differentiable from background.Figure D.16 shows where measurable groundwater impacts likely exist based on existinginformation.D.8 WMA 4-Specific Characterization Goals• Evaluate appropriateness of the current list of ROI• Determine level and extent of surface contamination• Identify soil waste stream characteristics• Obtain data to support Phase 2 planningA significant portion of the WMA 4 subsurface is known to be impacted by contaminatedgroundwater. In this portion of the WVDP premises, contaminated groundwater movement is ongoing,with the North Plateau Groundwater Plume growing as time progresses. A permeabletreatment wall has been deployed to address this contamination, and will likely alter the futurefate and transport of Sr-90 in this area. Additional characterization and enhanced monitoring arepart of the wall’s remedial design. Further characterization of subsurface contamination (soil andgroundwater) in WMA 4 is not within the current scope of the CSAP, beyond potentiallyvertically bounding the extent of surface contamination.Rev. 1 D-7