Conceptual Site Model - Argonne National Laboratory

WVDP Phase 1 CSAPFigure B.8 shows WMA 2 in 1984. The area is basically unchanged since 1977. The footprint ofthe French Drain is visible in this photograph.Figure B.9 shows WMA 2 in 1995. Lagoon 1 had been filled and covered in this photograph.There also is a significant surface disturbance in the northeast corner of WMA 2, adjacent toLagoon 3 which later became a hardstand area.Figure B.10 shows WMA 2 in 2007.Figure B.11 shows a 1982 oblique aerial photograph of the WMA 2 area taken from the east.B.4 Known and Suspected ReleasesB.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, and12 North likely are affected. Because Cs-137 is predominant, this area of contamination is knownas “the cesium prong” (DOE 2009 Table 2-17, DOE 2010 Section 3.11.5).As originally deposited, surface soil activity concentrations should have decreased towards thenorth, away from WMA 1. However, the surface features of many areas within the WVDPpremises have been reworked significantly since the release; as a result, the current spatial anddepth distribution of soil contamination may be significantly different than the original footprint.In addition, the surface soil contamination likely has been naturally spread by erosion and runoffinto surface drainage features; this phenomenon may have enlarged the area impacted byRev. 1 B-8