FIGURE 6-21. SUBSURFACE EXCISION ON ISLAND JANET. Soil was pushed out of the hole into a mound. The hole had standing water by the next day. Piled up soil was all removed, then the hole was backfilled and recontoured, (January 1979) 6.9.2 Final Program Soil profile samples collected and analyzed for the FPDB program during the spring of 1979 indicated the possibility of several pockets of contamination exceeding criteria; pockets which were missed by the earlier sampling (Figure 6-23). Criteria definitions had undergone some refinement between the fall of 1977 and early 1979, so the size of a pocket which would be recommended for excision was known: If the average TRU concentration was greater than 160 pCi/g in any layer extended to an area as great as one~sixteenth hectare, then that one-sixteenth hectare would be recommended for excision to a depth sufficient to remove the layer bearing the elevated TRU activity. At the time the results of the FPDB sampling became known, there was very little time left to excise and transport soil from other islands to Yvonne and still meet the demobilization schedule set by DNA. A sampling pattern had to be developed that would yield boundary definition results much more rapidly than could be obtained from sampling on every node of a 6.25-m grid. 190