Conceptual Site Model - Argonne National Laboratory

WVDP Phase 1 CSAPAPPENDIX DWMA 4 PRE-REMEDIATION DATA COLLECTIOND.1 BackgroundWaste Management Area 4 (WMA 4) is approximately 10 acres in size. The only WVDP facilitywithin WMA 4 is the Construction and Demolition Debris Landfill (CDDL) (see Figure D.1 formap). Disposal operations at the CDDL began as early as 1963 and continued through 1981 underNuclear Fuel Services and 1984 under the WVDP.D.2 Physical SettingWMA 4 is located on the North Plateau. It is bounded to the east by the WVDP fence line, to thenorth by WMA 12 North, to the west by WMA 5, and to the south by WMA 2.WMA 4 is vegetated. It is relatively flat, sloping towards the north and east. It is drainedprimarily by the Swamp Ditch which runs through WMA 4, along the north side of the CDDL.The Swamp Ditch and associated contributing ditches have been identified as radiological controlareas because of the discharge of contaminated groundwater from the North Plateau GroundwaterPlume. North of the CDDL there are several wetland areas where groundwater discharges beforeflowing off the WVDP project premises.WMA 4 is underlain by the sand and gravel unit which overlies the Lavery Till. The sand andgravel unit has been subdivided into the Thick Bedded Unit (TBU) and the underlying SlackWater Sequence (SWS), both of which are present beneath WMA 4. Groundwater in the sand andgravel unit flows to the northeast across the North Plateau, discharging to surface drainagefeatures such as the wetlands and Swamp Ditch, and to seeps off-premises along Franks Creekand Quarry Creek. The Lavery Till has low permeability but groundwater does flow verticallydownward through this unit recharging the underlying Kent Recessional Sequence.Rev. 1 D-1