“a
.
+
= ae on!
The first modification, labeled "village graveled" in Table IV reflects
the effect of covering the village areas with 1 to 2 inches of coral gravel.
Tobin indicated this practice was common throughout Micronesia (Private
Communication).
This action can be expected to reduce the gamma exposure
levels in the village area by approximately a factor of two.
The second and third modifications are based on the assumption that
clearing the islands for agricultural use and housing will result in some
mixing of the top soil.
It would appear that it would not be impractical ©
during this period to also plow many of the more contaminated islands to a
depth of about one foot.
Assuming that plowing results in mixing rather than
‘burying the top soil, we estimate average reductions in exposure rates of
t
about a factor of three would be obtained.
This reduction factor is based
on the present 3-5 em relaxation lengths for radionuclide depth distribution
in the uppermost soil layers of the more contaminated areas (this mean value
ee eae
atin
tee lage oe
varies considerably from site to site).
The reduction was then calculated
from exposure rate versus depth distribution data (HASL-258).
Modification