Conceptual Site Model - Argonne National Laboratory

WVDP Phase 1 CSAPThe subsurface of WMA 2 consists of a relatively permeable sand and gravel layer that overliesthe impermeable Lavery Till (Figure B.3). Some of the lagoons extend into the Lavery Till.Groundwater generally flows from west to east; however, there are some deviations from this rulein the northern and southern parts of WMA 2. In the northern part of WMA 2, some groundwaterflows north to discharge into the Swamp Ditch, which is a drainage feature that runs west-to-eastalong the north side of the CDDL (WMA 4). Along the southern boundary of WMA 2,groundwater likely has a southern component, leading to discharge into Erdman Brook. Further,Lagoons 2 and 3, near the eastern boundary, are unlined.There is known to be a significant amount of buried infrastructure (piping, etc.) associated withthe WMA 2 facilities.B.3 Area HistoryThe WMA 2 area (and in particular surface soils) has undergone significant reworking since theinitiation of NFS activities.Figure B.4 shows WMA 2 in 1962 prior to site development. At this time WMA 2 was farmed.Figure B.5 shows WMA 2 in 1966. The surface of WMA 2 shows surface scarring over almost itsentirety, with scarring extending from Lagoon 2 to the southeast into WMA 12 South. Lagoons 1,2, and 3 are clearly visible.Figure B.6 shows WMA 2 in 1968. Re-vegetation has occurred over much of the site. Dischargepoints from Lagoons 2 and 3 are clearly visible. The neutralization pit, solvent dike, and Test andStorage Building are also clearly visible along the western edge of WMA 2.Figure B.7 shows WMA 2 in 1977. A significant amount of additional construction has takenplace in WMA 2 since 1968. In particular, Lagoons 4 and 5 have been added, as well as a numberof additional structures in the western portion of WMA 2. Note that these activities would haveresulted in a potentially significant displacement of surface soils that would have beencontaminated by the 1968 Process Building stack releases.Rev. 1 B-7