Conceptual Site Model - Argonne National Laboratory

WVDP Phase 1 CSAPwould be of concern. Depending on the depth of the buried infrastructure, this could haveresulted in contamination at depths significantly greater than one meter.• The Old Hardstand was known to have been contaminated by releases associated with itsuse. The Old Hardstand was reworked as part of WVDP activities and the area is nowoccupied by the Lag Storage Buildings and the New Hardstand. As a result, soils in thevicinity of the Old Hardstand and beneath its footprint (now covered by pavement andportions of the Lag Storage Buildings’ slabs) are likely impacted also.• The 1985 WMA 3 condensate release likely resulted in contamination of the drainageditch that connected WMA 3 with the Old Hardstand area in WMA 5.• Sediments in the drainage feature that originally ran along the Old Hardstand anddischarged out the through the northeastern corner of WMA 5 is likely impacted fromOld Hardstand releases, and from contaminated surface soil erosion/deposition processes.• The foundation of the Lag Storage Addition 2 and associated soils are expected to becontaminated by releases associated with material stored in that facility.• Subsurface releases from the Process Building may have impacted subsurface soils andgroundwater in WMA 5 along its southeastern border. The western and northern extent ofthese subsurface soil impacts is unknown.• The prevalence of low levels of Sr-90 and tritium groundwater contamination in theeastern half of WMA 5 indicates other sources of contamination besides the ProcessBuilding. These could include contamination arising from historic hardstand spills, fromWMA 3, from buried infrastructure, or from other releases within WMA 5 that were notdocumented.Figure E.15 shows the current Conceptual Site Model (CSM) for surface soils. Based onhistorical direct gamma readings and the limited available historical surface soil sampling results,all surface soils within WMA 5 are considered potentially above surface soil CG w standards.Figure E.16 shows the CSM for soils deeper than 1 m. Subsurface soil contamination, if it exists,Rev. 1 E-11