Results of the separations area ground-water monitoring network for 1980

The monitoring program for assessing ground-water quality under low-level radioactive disposal facilities is based upon an understanding of the hydrology of this area. Knowledge of the ground-water flow system predicates well location, well completion, and sampling frequency. There were seven active cribs, and four active ponds and associated active ditches in 1980. The 216-A-3 Crib and the 216-S-11 Ditch are not monitored because they receive minor discharges. In 1980, concentrations of radionuclides (except tritium) in samples from the wells monitoring these active sites were below 10% of Table II guidelines. Tritium, in samples from wells monitoring 216-A-37 Crib, reached 33% of Table II guidelines and samples from a well monitoring 216-S-25 Crib exceeded Table II guidelines. The 216-A-37 Crib received discharges of 242-A Evaporator steam condensate containing tritium in concentrations as high as 4390 pCi/mL in 1980 (1.6 times Table II guidelines). Discharge of process condensate from the 242-S Evaporator to 216-S-25 Crib containied tritium concentrations as high as 3930 pCi/mL. Tritium is incorporated into water molecules and is not adsorbed onto the sediments. Therefore, the tritium discharged to a crib will move under unsaturated flow to the ground water. The other long-lived radionuclides prevalent in the waste stream are strongly adsorbed (Routson et al., 1979) and thus do not reach the ground water readily