Results of the Separations Area ground-water monitoring network for 1985

The purpose of this report is to present a summary of the results for calendar year 1985 of the Rockwell Hanford Operations (Rockwell) groundwater monitoring program for the Separations Area of the Hanford Site. The objectives of the monitoring program are to (1) evaluate the quality of ground water for compliance with Rockwell and DOE guidelines, (2) assess the performance of waste disposal and storage sites in the Separations Area, (3) determine the impact of waste disposal operations on the ground water, and (4) provide data for hydrologic analyses and model application. The 1985 Separations Area unconfined aquifer monitoring network included 127 wells. Water samples were collected monthly, quarterly, or semiannually from the wells in the network. These samples were selectively analyzed for total alpha, total beta, tritium, 90Sr, 137Cs, 60Co, 106Ru, uranium, and nitrate. Average radionuclide concentrations in monitoring wells for 1985 were similar to 1984, with the exception of wells at the 216-U-1/2 cribs. Water levels were measured in 224 wells to produce water table maps of the Separations Area (annually) and of the Hanford Site (semiannually). Radionuclide concentrations in the ground water within the Separations Area are compared with the Rockwell internal guidelines of RHO-MA-139, Environmental Protection Manual, Part L, which are applicable at the waste sites. These guidelines have their basis in DOE orders. The comparisons are conservative for the Separations Area since concentrations would be reduced by sorption, dispersion, dilution, and decay by the time flow reached the site boundary. Tritium, which is controlled on the basis of discharge concentrations, did not exceed the radioactivity levels specified in RHO-MA-139. Cases where guidelines were exceeded at active liquid waste disposal facilities and inactive facilities are reported