As at many other locations, the hydrologic, geologic, climatic, and demographic characteristics of the Savannah River Plant do not encourage the disposal of radioactive waste to the environment. Disposal to the ground has been limited to the burial of solid waste and the discharge of very low-level liquid waste to seepage basins. Although solid wastes are subjected to leaching by an annual rainfall of 40 inches, no radionuclides have been detected in ground water from this source. Seepage-basin retention of radionuclides has been less satisfactory, since liquid waste is usually acidic (pH 3-4), and strontium^ is poorly adsorbed on local soil under these conditions. Strontium^ is detectable in sand layers (at concentrations less than the Radioactivity Concentration Guide) as far as 500 feet from the basins. Fission-product tritium, present as water, is not adsorbed and thus serves as a useful ground-water tracer.

The path of radionuclide migration from seepage basins excavated in the Hawthorn Formation (Miocene) is determined by the geology and hydrology of each disposal area. Most of the radionuclide migration has been through sandy strata or sand-filled clastic dikes. Wherever the soils do not contain these imperfections, migration has been slow.

The areal and detailed hydrology, lithology, and structure of waste-disposal areas are presented, with emphasis on those factors that influence the safety of disposal. The migration patterns of radioactive ground water from the seepage basins during the period February through September 1962 is traced by detailed measurements on maps and diagrams.