URANIUM CONTAMINATION IN THE GREAT MIAMI AQUIFER AT THE FERNALD ENVIRONMENTAL-MANAGEMENT PROJECT, FERNALD, OHIO

Ground-water investigations at a former U.S. Department of Energy nucl ear weapons complex near Fernald, in southwestern Ohio, included the d elineation of uranium contamination above the USEPA pro posed drinking water standard of 20 mu g/l. Contamination occurs in a buried valley and has migrated > 1.5 km south-southeast of the facility boundary. Fl ooring of the plume(s) appears to be congruent to 32 m below the water table of the Great Miami Aquifer. U6+ predominates in the modeled U-O -2-CO2-H2O system and U retardation decreases at depth. U-234/U-238 di sequilibria analyses complement hydrogeologic studies which suggest th at U leakage through the clayey till cap is less significant than the predominant transport pathway of infiltration via drainage channels in cised into the aquifer.