Process wastes are stored on site in rubber-lined and clay-lined pits and in large tanks at the U.S. Department of Energy Feed Materials Production Center (FMPC), where purified uranium and uranium compounds are produced. Water samples collected from off-site domestic and commercial wells in December 1981 and in August 1982, contained concentrations of dissolved uranium that ranged from < 0.4 to 430 micrograms/L (ug/L). The wells whose samples contained unusual concentrations of uranium (> 10 ug/L) lie roughly along a line extending about 2000 ft south from the southern boundary of FMPC. The offsite area affected by these concentrations is probably < 100 acres. It is not possible to determine the exact point of origination of contaminants in the groundwater on the basis of available data. (Author 's abstract)