Radiological status of the ground water beneath the Hanford Site, January-December 1981

During 1981, 299 monitoring wells were sampled at various times for radionuclide chemical contaminants. This report is one of a series prepared annually to document and evaluate the status of ground water at the Hanford Site. Two substances, tritium and nonradioactive nitrate, are easily transported in ground water; therefore, these substances are used as primary tracers to monitor the movement of contaminated ground water. Data collected during 1981 describe the movement of tritium and the nonradioactive nitrate plumes as well as their response to the influences of ground-water flow, ionic dispersion, and radioactive decay. The gross beta (106Ru) levels have become so low that it will no longer be considered a major radionuclide contaminant. The tritium plume continues to show increasing concentrations near the Columbia River. While it is mapped as having reached the Columbia River, its contribution to the river has not been distinguished from other sources at this time. This plume shows much the same configuration as in 1977, 1978, 1979, and 1980. The size of the nitrate plume appears stable. Concentrations of nitrate in the vicinity of the 100-H Area continue to be high as a result of past leaks from the evaporation facility. The overall quality of the ground water at the Hanford Site is generally comparable to that of other ground waters in eastern Washington. Any exceptions to this statement will be noted in this report