FIGURE 6-26. CACTUS CRATER/DOME ON YVONNE. Debris and soil disposal is nearing completion and placement
of cap sections is well underway. (Summer 1979)
6.10.3 Fig/Quinee Excision
By 14 April 1979, the top 20 em of soil had been removed ("lifted") from about three hectares
surrounding and including the Fig/Quince area, and post-lift in situ measurements were completed.
All measurements in the area were made on a 25-m grid, so each node represented a one~sixteenth
hectare square. Prior to any lift (removal of the top 20 em of soil), 47 squares had indicated TRU
greater than 160 pCi/g, with an average of about 600 pCi/g. The indicated TRU concentration
increased in a few of the squares following the first lift with one square, 0-BL~0, showing an increase
from about 4,100 pCi/g up to about 7,000 pCi/g. (These numbers are only "about" because the
TRU/241Am ratio was approximated from NVO-140 data; samples with high levels of radioactivity
were not processed in the RADLABfor reasons explained in Chapter 4.) The post4ift average TRU
in the 47 squares was about 560 pCi/g. When the extra high values at 0-BL-0 are removed from the
computations, the pre- and post-lift means become about 515 and 420 pCi/g, respectively. The
number of squares with indicated TRU above 160 pCi/g was reduced to 30 by the soil removal; the
average of these 30 was about 810 pCi/g including point 0-BL-0 and about 580 pCi/g excluding
0-BL-0.
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