Conceptual Site Model - Argonne National Laboratory

WVDP Phase 1 CSAPI.7 Conceptual Site ModelNone of the buildings within the WMA 10 boundary are believed to have been impacted byradioactive contamination. Soil surfaces that were exposed at the time of the 1968 airbornereleases would have been impacted to some degree. The majority of WMA 10 was exposed soilsurface at that time. Since then there has been significant reworking of WMA 10 surface soils,including paving activities. Consequently, there is the potential for surface soil contaminationabove background conditions for exposed soils, and also the possibility of contamination beneathexisting pavement and clean fill material. The highest concentrations would likely be along thenortheastern edge of WMA 10 along WMA 1, closest to the original 1968 airborne releases, andin the footprint of surface drainage features present within WMA 10.The only structure present in 1968 was the Administration Building and the Security Gatehouse.There is the possibility of contaminated soils underneath building foundations built after 1968.The most likely facilities where this would be the case are the New Warehouse, the formerContractor Fabrication Shop, and the Vit Hill trailer pads, whose footprints fall within elevatedgross activity identified by the 1982 direct gamma survey.There also is the possibility of low level contamination associated with storm water sewerspresent in WMA 10 at depths greater than 1 m. This contamination may have been introducedwhen the present storm water configuration was installed due to the use of contaminated soils asbackfill material, and/or from leakage from the system. If contaminated fill material is present, itis most likely to be associated with the northernmost portion (within WMA 10) of the stormsewer system since this is where historical surface soil contamination would have been thegreatest.Finally, one background soil core within WMA 10 along its border with WMA 6 encounteredelevated tritium in soils at a depth of 5 to 7 feet. This is most likely due to subsurfacecontamination extending from WMA 6. The soil core location was approximately 55 msouth/southwest of the current sewage treatment facility.Rev. 1 I-8