Conceptual Site Model - Argonne National Laboratory

WVDP Phase 1 CSAP• Direct measurement gamma surveys were conducted over portions of the WVDPpremises in 1982 and 1990-1991; however, no direct measurement gamma data werecollected for the WMA 12 North area.• There has been no sediment or soil sampling from within the WMA 12 North footprintavailable in the ELIMS database.• There has been no groundwater data collection from within the WMA 12 North footprintthat is reported in the ELIMS database.K.6 Planned Phase 1 DP ActivitiesThere are no planned Phase 1 decommissioning activities for WMA 12 North.K.7 Conceptual Site ModelBased on the very limited available information, the conceptual site model (CSM) for WMA 12North is as follows. No environmental releases of contamination within WMA 12 North arebelieved to have occurred. However, environmental media within WMA 12 North likely havebeen affected to some degree by releases elsewhere on the WVDP premises. These include airdeposition contamination on surface soils, most likely along the western and southern portions ofWMA 12 North since these were in closest proximity to WMA 1, and potential reworking of thatcontamination by erosional processes in the vicinity of WMA 12 North.Pond sediments may be of concern since these ponds would have served as a settling basin forcontaminated soils eroded from surrounding surface soils. The ponds appear to have been presentfor forty years.Figure K.9 shows the current CSM for surface soils. Figure K.10 shows the CSM for soils deeperthan 1 m. The assumption is that it is unlikely that there is soil contamination deeper than onemeter within WMA 12 North. The assumption also is that there are no significant groundwaterimpacts within WMA 12 North; the most likely source of groundwater contamination would havebeen migration associated with the North Plateau Groundwater Plume. 2008 characterizationRev. 1 K-4