Conceptual Site Model - Argonne National Laboratory

WVDP Phase 1 CSAPThe WVDP Trenches contain approximately 200,000 cubic feet of LLW resulting fromdecontamination activities performed between 1982 and 1986.The trenches are typically about 30 feet deep and about 15 feet wide. The lengths vary from 30feet to 250 feet. Trenches 9 and 11 have composite liners and caps. All other WVDP Trenches arecapped with clay.WVDP Caissons. Four WVDP Caissons were constructed by the WVDP near the eastern andsouthern corners of the NDA. The caissons are steel-lined concrete cylindrical vaults.WVDP disposal records indicate approximately 823 cubic feet of waste in drums was placed inCaisson 1. The WVDP disposal records do not indicate that any waste was placed in the otherthree caissons. The report, “Estimated Radionuclide Inventory for the NRC-licensed DisposalArea at the West Valley Demonstration Project” (Wild 2000), indicates that drums containingapproximately 823 ft3 of general waste and sludge from the O2 Building (the original Low-levelWaste Treatment Facility) were placed in Caisson 1.The WVDP Caissons are seven feet in diameter and 60 feet deep, finished so that the top of thecaissons were even with the ground surface. The caissons are plugged with concrete for shieldingand covered with a plastic shield to prevent rainwater infiltration.Interceptor Trench and Liquid Pretreatment System. The Interceptor Trench and associatedLiquid Pretreatment System were installed after groundwater contaminated with tributylphosphate, n-dodecane, and several radionuclides was detected in a well in the NDA. Thepurpose of the project was to intercept potentially contaminated groundwater migrating from theNDA.The Interceptor Trench is located on the northeast and northwest boundaries of the NFS WasteDisposal Area. The base of the trench extends to a minimum of one foot below the interface ofthe weathered Lavery Till with the unweathered Lavery Till. The trench is drained by a drainpipethat directs accumulated water to a collection sump. The collection sump has a submersible pumpto transfer groundwater to the Liquid Pretreatment System. As of 2008, no groundwater has everbeen transferred to the Liquid Pretreatment System.Rev. 1 G-3