Conceptual Site Model - Argonne National Laboratory

WVDP Phase 1 CSAPFigure C.5 shows WMA 3 in 1968. Vegetative cover appears to be returning to the WMA 3surface in this photograph.Figure C.6 shows WMA 3 in 1977. There are no significant changes from 1968.Figure C.7 shows WMA 3 in 1984. There are no significant changes from 1977. As is clear fromthis photograph, the majority of the WMA 3 surface is vegetated or exposed soils.Figure C.8 shows WMA 3 in 1995. Significant surface changes have occurred since 1984, withthe construction of numerous new facilities and above-ground infrastructure.Figure C.9 shows WMA 3 in 2007. There are no significant changes since 1995.Figure C.10 shows a recent oblique aerial photograph of the WMA 3 area taken from thenorthwest. As is clear from this photo, the ground surface has been covered by paving materialwith little evidence of vegetation remaining. Based on historic aerial photographs, the groundsurface was paved sometime after 1984.C.4 Known and Suspected ReleasesC.4.1Cesium ProngPotentially Affected Media:Potentially Affected WMAs:surface soil, subsurface soil, sediments1, 2, 3, 4, 5, 6, 10, 12 NorthIn 1968, a ventilation system filter in the Process Building (in WMA 1) failed, releasingcontaminated particulate up the Process Building stack. A mixture of radionuclides was released,with Cs-137 predominant. Approximately 0.33 Ci particulate gross beta radioactivity wasreleased. The contaminated particulate was deposited on surface soils, resulting in a large area ofcontamination around the Process Building and to the north-northwest. Detectable depositsextend several miles, including beyond the WVDP premises. WMAs 1, 2, 3, 4, 5, 6, 10, and 12North likely are affected. Because Cs-137 is predominant, this area of contamination is known as“the cesium prong” (DOE 2009 Table 2-17, DOE 2010 Section 3.11.5).Rev. 1 C-5