Conceptual Site Model - Argonne National Laboratory

WVDP Phase 1 CSAPsamples. 10 pCi/L and 500 pCi/L were selected as thresholds for Sr-90 and tritium,respectively, because based on ELIMS data results above these activity concentrationswere consistently above method detection limits and so indicative of contaminationimpacts rather than simply measurement error. Contamination was encountered at bothlocations. It is not clear if this contamination represented releases from WMA 3activities, or originated from releases associated with the main processing facility’sactivities.C.6 Planned Phase 1 DP ActivitiesFor a more complete description of planned Phase 1 DP activities, see the Phase 1 DP, Section3.1 and Section 7.5.The waste tank mobilization and transfer pumps, the Con-Ed Building, the Equipment Shelter andcondensers, and the piping and equipment in the HLW transfer trench are slated for removal aspart of Phase 1.Phase 1 does not include the four underground waste tanks, the Permanent Ventilation SystemBuilding, the Supernatant Treatment System Support Building, the high level waste transfertrench itself, or the underground infrastructure.Some Phase 1 activities planned for WMA 1 affect WMA 3. These include a temporary sheetpiling wall that will run along a portion of the WMA 1 and WMA 3 boundary, and a permanentslurry wall that will extend into WMA 3 (Figure C.15). Depending on the outcome of CSAP datacollection work, the planned excavation in WMA 1 may be revised in a way that extends intoWMA 3.C.7 Conceptual Site ModelBased on the limited available information, the conceptual site model (CSM) for WMA 3 is asfollows. A number of potential releases within the WMA 3 footprint are known to have occurred,or may have occurred that likely impacted surface and subsurface soils and groundwater. Inaddition, environmental media within WMA 3 have likely been affected to some degree byreleases elsewhere at the WVDP site. These include air deposition contamination on surface soilsRev. 1 C-10