Conceptual Site Model - Argonne National Laboratory

WVDP Phase 1 CSAPeastern ends of the NDA, various support facilities immediately above the NDA for leachatecollection, and the NDA Hardstand in the southeastern portion of the area.The WMA 7 area is drained by two drainage features, one running along the eastern boundary ina northerly direction, and the second that runs along the northern boundary in an easterlydirection. Both features eventually drain into Erdman Brook.The WMA 7 area is underlain by the weathered and unweathered Lavery Till. The weatheredLavery Till allows some groundwater movement. Groundwater within the weathered Lavery Tillflows to the northeast, following the surface topography.The unweathered Lavery Till is a relatively impermeable unit. Groundwater flows verticallythrough the unweathered Lavery Till to the Kent Recessional Sequence.Within the unweathered Lavery Till there is a layer known as the Kent Recessional Sequence thatis more permeable and that does transport groundwater. Groundwater within the KentRecessional Sequence, in general, moves to the northeast, discharging to Buttermilk Creek.Subsurface features associated with the NDA extend through the weathered Lavery Till into theunweathered Lavery Till, but do not penetrate the Kent Recessional Sequence.Figure G.4 shows a west-to-east cross-section of the subsurface through the NDA.G.3 Area HistoryFigure G.5 shows the WMA 7 area in 1962, before site development. The area at that time wasfarmed.Figure G.6 shows the WMA 7 area in 1966. The area had already been largely cleared, althoughfrom this photograph it is not possible to determine its use.Figure G.7 shows the WMA 7 area in 1968. Area development has continued, with the footprintof the NDA now fairly well-defined.Rev. 1 G-6