N Ng f \ \ ‘N ~ f sy / OCEAN _ — LAND BRIOGE TO SALLY NE a ~ —S$2 —-§4 —— $6 APPROXIMATE HIGH TIDE LINE, [972 TILDA- BIJIRE —s ° -_———_—_4 50m —sI9 — $lez | —si4 FIGURE 7-42, ISOPLETH ON FINAL ESTIMATED SURFACE TRU ACTIVITY IN pCi/g FOR ISLAND TILDA line with conservative health physics practices, ERDA would recommend an air sampling program and a minimal program to monitor fresh excavation during initial phases of earth moving operations to document that the soil conditions and actual air concentrations are within national guidelines." 1972 Survey Results Soil samples were collected at 31 locations on Ursula during the 1972 survey, and a vegetation and an animal sample were also taken. At 28 locations, the samples were 0-15 cm cores and three locations were profile sampled from 0 to 35 em. Each of the profile results showed a different distribution of activity with depth. One showed a homogeneousdistribution of 137g, 90sr and 239,240py activities down to a depth of 15 em, and then a steady decline in activity below that depth. Another profile indicated a slight increase in activities of the four isotopes with increasing depth but the level of activities was still low. The third profile showed that the 742™Pu activity dropped sharply and then increased slightly, whereas the 137Cg and 99Sp activities dropped less sharply and then leveled off. Tables 7-1, 7-2 and 7-3 summarize the 0-15 em data for 137Cs, 90sp and 239:240py, respectively, for the 1972 sampling of Ursula. 293