Conceptual Site Model - Argonne National Laboratory

WVDP Phase 1 CSAPshine from facility buildings; however, they are patterns that are potentially indicative ofsoil contamination and are consistent with what would have been expected from airdeposition resulting from stack releases.• In 1990 and 1991, a second static direct exposure measurement program was conductedacross the WVDP premises (WVNSCO 1992). In the case of WMA 10, this effortprovided systematic coverage on a 10-m grid, with the exception of the northern portionof WMA 10. This data collection used different instrumentation/protocols than the 1982study, so the results are not quantitatively comparable. Figure I.11 shows these resultsoverlain on a 1984 aerial photograph. The patterns of gross activity values match thoseobserved in 1982.• There have been two soil sampling activities in WMA 10 (Figure I.12) that resulted insample results contained in ELIMS. In 1993, soil samples were collected from fourlocations; three locations were surface samples only and one location was sampled todepth. In 2008, three additional locations were sampled as part of a subsurfacebackground study; at each location, soil samples were retrieved from depths greater thanone meter. Table I.1 identifies the number of samples analyzed for each of the 18 primaryradionuclides of interest (ROI) from these two sampling programs. The 1993 samplingprogram only included Am-241, Cs-137, Sr-90, the plutonium isotopes, and the uraniumisotopes. The 2008 background sampling program addressed all 18 ROI. Neithersampling program collected surface samples from the northeastern portion of WMA 10,which is the portion most likely affected by contamination.All Cs-137 results were less than one pCi/g and all Sr-90 results were non-detects. Theseresults are not surprising because surface samples were not collected in areas most likelyto have been impacted by site activities. Of the four subsurface cores (one from 1993 andthree from the 2008 background study), one sample from a depth of 5 to 7 feet fromGPBG0408 reported elevated gross beta and tritium concentrations above backgroundconditions. While these values were not high, they were indicative of impacts. Tritium isthe most mobile site contaminant, and while not one of the 18 ROI, tritium does serve asa marker of subsurface site impacts. GPBG0408 is immediately adjacent to WMA 6,along the eastern edge of WMA 10.Rev. 1 I-6