Conceptual Site Model - Argonne National Laboratory

WVDP Phase 1 CSAP• In addition, Lagoon 3 periodically has discharged effluent to Erdman Brook through theLagoon 3 SPDES permitted outfall. Of particular historical note were the relatively largereleases that took place during NFS operations, such as in 1969 when 108 curies of gross betaactivity were released (WVDP-EIS-006). Between 1966 and 1972, a yearly average of0.7 Ci of alpha emitters, 65 Ci of beta emitters, and 3,500 Ci of tritium were released.Subsequent radioactive discharges from Lagoon 3 were related to treatment of SDA leachate(1975 – 1981) and from NFS and WVDP facility operations (1972 – present). Several of thedischarged radionuclides have an affinity to become chemically sorbed to silt, whichaccumulates in stream beds (DOE 2008 Section 2.12.3).These operational units are in the vicinity of the North Plateau Groundwater Plume, and likelyhave contributed to the plume. Based on their specific construction (e.g., depth) and locations,groundwater contamination also is likely to have migrated south from some of these units,through the sand/gravel layer, towards Erdman Brook.Finally, in 2004 two radiologically contaminated bees’ nests were found when a walkway wasremoved between the Vitrification Test Facility and a nearby trailer in WMA 2. Experienceindicated that the nests likely were built with mud from one of the lagoons. This incident isrepresentative of cases where low-level contamination has been found to be spread by insects orsmall animals (DOE 2010 Section 3.11.5).B.4.3.2Lagoons 4 and 5 OverflowPotentially Affected Media:Potentially Affected WMAs:surface soil, subsurface soil, groundwater1, 2, 3, 4, 5, 6 (North Plateau Groundwater Plume)In 1974, Lagoons 4 and 5 overflowed due to loss of capacity at Lagoon 3; this resulted inunplanned treated water released to local soil and groundwater northeast of the O2 Building.Treated water activity concentrations likely were close to surface water free release levels(DOE 2009 Table 2-17). This release likely has contributed to the North Plateau GroundwaterPlume.Rev. 1 B-11