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