Conceptual Site Model - Argonne National Laboratory

WVDP Phase 1 CSAP(DOE 2009 Table 2-17; DOE 2010 Section 3.11.5). This release likely has contributed to theNorth Plateau Groundwater Plume.B.4.3.6Old Hardstand ReleasePotentially Affected Media: surface soil, subsurface soil, groundwaterPotentially Affected WMAs: 1, 2, 3, 4, and 5In 1982 and 1983, evidence of a significant release of radioactivity was discovered at the OldHardstand in WMA 5. This release was apparently associated with outdoor storage ofcontaminated equipment and radioactive waste by NFS. Leakage from that equipmentcontaminated the hardstand’s asphalt surface and the adjacent soil and drainage ditch. Gammaradiation levels as high as 1,500 mR/hr were measured two inches above the ground surface. In1983, aboveground portions of contaminated trees were removed. In 1984, approximately 1,700cubic yards of materials (asphalt, soil, vegetation) were removed from the area and placed in thedecommissioned Lagoon 1. (Waste from Lagoon 1 had previously been transferred to Lagoon 2;both lagoons are in WMA 2.) Lagoon 1 was then capped with a clay cover. A 1995 estimate ofthe activity in the debris placed in Lagoon 1 totaled approximately 18 Ci (DOE 2009 Table 2-17;DOE 2010 Section 3.11.5). This release likely has contributed to the North Plateau GroundwaterPlume.B.4.3.7Waste Tank Farm Valve Pit SpillPotentially Affected Media: surface soil, subsurface soil, groundwaterPotentially Affected WMAs: 1, 2, 3, 4, and 5In 1985, a spill of radioactive water occurred in a valve pit located in WMA 3, northwest of Tank8D-2. A condensate line failed at its flanged valve bolts. Approximately 500 gallons werereleased at 4.6 E-02 uCi/mL gross beta and 4E-03 uCi/mL tritium. Some condensate flowed outof the valve pit into the drainage ditch extending towards the Old Hardstand in WMA 5 and/ortowards WMA 2. The radioactive condensate reached the point in the drainage ditch where theditch turns to the northeast, near the corner of the New/Old Hardstand. At this point, the ditch wasblocked to prevent further downstream flow. The release primarily impacted surface soil in WMARev. 1 B-13