Time pattern of off-site plutonium deposition from rocky flats plant by lake sediment analyses

OU3 sediment dating and sedimentation rates

“…in Mower Reservoir (MR). RFS sediment dating for Operable Unit 3 compared favorably with the Hardy, Livingston, Burke, and Volchok Standley Lake study (Hardy et al 1978).…”

“…During the history of activities, releases of contaminants into the environment occurred due to early operational practices during the 1950's and 1 9 6 0 '~~ holding pond reconstruction between 1970-1 973, and an airborne radionuclide release during a building fire in 1969. Recent studies illustrated plutonium concentrations over normal global fallout in the 1969 sedimentation year for GWR and SL creating an independent dating marker Hardy et al 1978). The 1969 fire was used as the plutonium peak for this study.…”

“…Lack of adequate sample size prevented 210Pb dating measurement. To verify cesium/plutonium dating results, RFS used historic sediment dating information from studies performed by Hardy et al (1978), EPA (1973), Thomas and Robertson (1981), and Rockwell (1 985).…”

The history of plutonium and cesium-137 contamination of the Ob River delta sediments

“…an upward tail forms. This feature was observed many times in sediment cores at many locations (Breteler et al, 1984;Wan et al, 1987;McCall et al, 1984;Smith and Ellis 1982;Hardy et al, 1980, Livingston, 1979). …”

“…The large Cs-137 maxima can also be used to estimate average sedimentation rates if one assumes that these maxima represent layers deposited in 1963, when the maximum in global fallout was observed (Table 9). This technique has been widely used to date sediment cores (Breteler et al, 1984;Hardy et al, 1980).…”