Conceptual Site Model - Argonne National Laboratory

WVDP Phase 1 CSAPPlateau although there probably is also localized discharge to Erdman Brook. The Lavery Till haslow permeability but groundwater does flow vertically downward through this unit recharging theunderlying Kent Recessional Sequence.The weathered Lavery Till is exposed at the surface in the southern half of WMA 6. Groundwaterin the weathered Lavery Till flows to the northeast across the South Plateau with likely dischargeto Erdman Brook.WMA 6 is drained by Erdman Brook via ditches that run parallel to the railway line.F.3 Area HistoryFigure F.3 shows the WMA 6 area in 1962, prior to site development. At this time the WMA 6area was bifurcated by a public road, there was a residence within its boundaries, and a portion ofit was farmed.Figure F.4 shows the WMA 6 area in 1966, after site development had begun. WMA 6 wasaffected primarily by the completion of a road connecting the main plant area with theNDA/SDA, the installation of the railway, and the construction of the demineralizer sludgeponds, cooling towers and old sewage treatment plant in the northern portion of WMA 6.Figure F.5 shows the WMA 6 area in 1968. The primary change is the expansion ofhardstand/open storage/staging areas west of the WMA 7 area within the southern end of WMA6.Figure F.6 shows the WMA 6 area in 1977. Nothing of significance had changed since 1968 otherthan a lessening of activity at the south end of WMA 6.Figure F.7 shows the WMA 6 area in 1984. There were no significant changes from 1977.Figure F.8 shows the WMA 6 area in 1995. There were significant changes between 1984 and1995, including the construction of additional hardstands, the Sewage Treatment Facility, theconstruction of the Equalization Basin, and various other smaller supporting facilities in thenorthern area of WMA 6.Rev. 1 F-4