Conceptual Site Model - Argonne National Laboratory

WVDP Phase 1 CSAPthe sanitary sewer line was believed responsible for elevated gross beta and Sr-90 levels observedin the sewage outfall from 1972 through 1974 (DOE 2009 Table 2-17; DOE 2010 Section 3.11.5).This release likely has contributed to the North Plateau Groundwater Plume.A.4.3.2Waste Transfer FailurePotentially Affected Media:Potentially Affected WMAs:subsurface soil, groundwater1, 2, 3, 4, 5, 6 (North Plateau Groundwater Plume)In 1967, the wastewater line to Tank 8D-2 (Line 7P-170-2A) failed during waste transfer from theProcess Building to the tank (in WMA 3). The failure resulted in approximately 555 gallons ofliquid waste entering an acid recovery sump in the southwest corner of the Process Building anddraining to the Old Interceptor (in WMA 2). Resultant activity levels at the Old Interceptor weregreater than 100 mR/hr. The waste required pump-out back to the Process Building for treatment.This event led to installation of 12 inches of concrete shielding on the Old Interceptor floor. In2003, a gamma radiation level of 408 mR/h was measured near the Old Interceptor tank floor(DOE 2009 Table 2-17; DOE 2010 Section 3.11.5). This release likely has contributed to theNorth Plateau Groundwater Plume.A.4.3.3Laundry Line LeakPotentially Affected Media:Potentially Affected WMAs:surface soil, subsurface soil, groundwater1, 2, 3, 4, 5, 6 (North Plateau Groundwater Plume)In 2003, a hole was discovered in a riser for a wastewater drain line (drain line 15-ww-569) thatconnected the Laundry (on the south side of the Process Building) to the Interceptors (in WMA2). The initial date of the breach was unknown, no specific event was identified which wouldhave caused the breach, and the line was repaired. The hole had allowed contaminated laundrywater to leak into soils adjacent to the riser (in WMA 1) at a rate of approximately 900 gallonsper day. A sample of subsurface soil near the breach identified 3,300 pCi/g Cs-137 and 87 pCi/gAm-241, though the breached line might not have been the only contaminant source (DOE 2009Table 2-18; DOE 2010 Section 3.11.5). This release likely has contributed to the North PlateauGroundwater Plume.Rev. 1 A-6