IV.
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SOLL CLEANUP
A. GENERAL
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J. The Cleanup ‘guidelines specify removal of soil when Pu con~
centration exceeds 400 pCi/g regardless of the depth at which the contaminated
soil is. found, and a negotiable removal of soil when Pu concentration is in
the range of 40-400 pCi/g. The guidelines obviously do not intend that soil
cleanup involve a complete search of the AtollforburiedPu, rather buried Pu
‘should be looked for emily where it is suspected of being present.
The suspected
locations are listed in Enclosure 2.
The AEC Survey confirmed the presence
of buried Pu exceeding 400 pCi/g on Boken (Irene), Lujor (Pearl) and Runit
- (Yvonne).
Cleanup will excise these contaminated burial sites, and investigate
the others in Enclosure 2 tg determine if they too warrant removal. However,
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unless additional information is forthconjng
est that high Pu con-
centrations exist beneath the surface elsewhere, only those sites [isted in
Enclosure Z will be SéarchnegLor buried Pu contaminated soil.
Since the major
hazard of Pu results from resuspension into the air, and that is more feasible
.from the surface than from depths beneath the surface, soil cleanup will primarilyZocus on
©. Adentifying end Temoving Pu Sontaminated soitfrom bhe auxsece.
nF
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2. The AEC Survey reports analyses of soil samples collected
from about 1100 spots throughout Enewetak Atoll.
Samples from about 900
of these spots were labeled as "surface samples" containing soil from within
30 om? of ground and to a verticaldepthof15cn. The remaining spots
yielded "profile samples."
Each soil profile was for a column
of ground whose surface area was 100 cm“
and which was sectioned
into component profile samples at depth increments of 0 to 2, 2 to 5, 5 to 10,
10 te 22, 15 to 25, 25 to 35 cm and at 10-cm increments to the total depth
sampled which varied from as little as 35 cm as to as much as 185 cm.
The
surface samples thus had a volume of 450 cm while the profile samples had
either 200, 300, 500 or 1000 cm.
Samples were analyzed for Pu as well as
other radioactive elements, including Am-241.
3.
From 306 surface samples and 55 profiles (approximately |450 addi-
tional samples) taken on {slands in the south,
Boko
(Sam) clockwise through
Kidrenen (Keith), it was found that no sample had a Pu concentration preater
than 1.1 pCi/g and most had much less than this amount. The absence of
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significant contamination on these islands was expected as none were the site
of any nuclear tests, and they were not downwind of sites where tests did occur.
Since the soil data obtained are consistent with other facts (aerial survey,
nuclear test locations, fallout patterns), it is reasonable to assume that the
southern islands avoided receiving any Pu at concentration levels which might
warrant soil removal as part of Cleanup.
The southern islands as a group
fali in the “no cleanup required" category.
4.
For the northergp islands, on the other hand,
surface samples
and59profileswere reported in the AEC Survey to have Pu concentrations
exceeding 40 pCi/g, and eight of these profiles included| samples | with more
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