Conceptual Site Model - Argonne National Laboratory

WVDP Phase 1 CSAP• Lagoon 1 was an unlined basin excavated into the sand and gravel unit. It measuredapproximately 80 feet long on each side and 5 feet deep. It had a storage capacity of morethan 200,000 gallons. Lagoon 1 was fed directly from the Old Interceptor and the NewInterceptors. It was removed from service in 1984. Most of the contaminated sediment wastransferred to Lagoon 2. Lagoon 1 was filled with contaminated debris from the OldHardstand (WMA 5), including contaminated asphalt, soil, and vegetation, and then cappedwith clay and topsoil.• Lagoon 2 is an unlined basin excavated in the un-weathered Lavery Till. It measuresapproximately 200 feet long by 100 feet wide and 17 feet deep. It has a storage capacity of2.4 million gallons. Historically, Lagoon 2 was fed directly by Lagoon 1; therefore it containscontaminated sediments from the 1984 Lagoon 1 closure. Currently, Lagoon 2 is fed directlyfrom the New Interceptors, the NDA interceptor trench, the tank farm and at times the NorthPlateau Groundwater Recovery System; it is part of the Low-Level Water Treatment Facility.• Lagoon 3 is an unlined basin excavated in the un-weathered Lavery Till. It measuresapproximately 230 feet long by 130 feet wide and 24 feet deep. It has a storage capacity of3.3 million gallons. Lagoon 3 receives treated water from Lagoons 4 and 5. Lagoon 3 isperiodically batch discharged to Erdman Brook through a State Pollutant DischargeElimination System (SPDES) permitted discharge; it is part of the Low-Level WaterTreatment Facility.• Lagoon 4 is a lined basin constructed in the sand and gravel unit on the North Plateau. Itmeasures approximately 100 feet long by 90 feet wide. It has a storage capacity of 204,000gallons. It receives only treated water from the LLW2 Building and discharges to Lagoon 3.Lagoon 4 was originally lined with reworked glacial tills. In 1974, a synthetic membraneliner was installed after NFS identified that Lagoons 4 and 5 were potential sources of tritiumto groundwater in the sand and gravel unit. In the late 1990s, the synthetic membrane linerswere removed and replaced with concrete grout and a XR-5 liner, which is an ethylene interpolymeralloy membrane.• Lagoon 5 is very similar in form and function to Lagoon 4, and shares the same history. It isa lined basin constructed in the sand and gravel unit on the North Plateau. It measuresRev. 1 B-2