Report on the Oak Ridge sewage sludge land-farming experience. Part 1. Data presentation

Disposal of sludge from the City of Oak Ridge's sewage treatment facility on a 65-acre site on the Department of Energy's Oak Ridge Reservation was initiated in November 1983. On March 22, 1984, DOE and the City determined that the sludge contained radioactive materials. Application of sludge on the Reservation was suspended on March 25 and a comprehensive survey and sampling plan was instituted to radiologically characterize the disposal site. By April 1, a radiation walkover survey had been completed on the site and samples of air, water, and soil had been collected to be analyzed for the presence of radionuclides. The mean air dose rate, one meter above the ground surface, was found to be 13 μR/h with a range from about 8 μR/h, which is the usual background level in the area, to 21 μR/h. Concentrations of Cs-137 and Co-60, the principle contaminants in the soil, were essentially below the analytical detection limits in the air and water. About 350 soil samples were collected by extracting cores to a depth of 12 to 15 inches according to a systematic random sampling design. Each core was separated into three sections; the top 3 inches, a middle section, and the bottom 3 inches to represent layers on the site. The majority of the radioactivity was determined to be in the upper 3 inches of soil. A statistical treatment of the analytical results provided an estimate of the total activity at the site, the vertical distribution of the gamma activity, and the areal distribution of the primary radionuclides. A total of 170 mCi of activity was estimated as present in the top 3-inch layer of the 65-acre site, 69% of which was contributed by Co-60 and Cs-137, 23% by U-234 and Sr-90, and 8% by other minor radionuclides. 4 references, 12 figures, 43 tables