0-5 em 90sr, pCi/g 137s, pCi/g 40.6 20.5 0-40 em 0-60 em 21.8 10.4 17.0 rc 7.9 Total Samples 573 2,126 Table 7-3 summarizes the 0-15 em results for 239,240 py, as estimated from 24lAm. When the 50 m Samples had been analyzed for 24lam, two locations showed estimated subsurface TRU activity exceeding 160 pCi/g. The two locations, NW 20-4 and SW 6-10, were investigated by taking sidewall samples at 6.25 m or 12.5-m intervals around the original high values. As shown by Figure 7-70, there was no further evidence of elevated subsurface TRU activity at SW 6-10. However, the sampling around NW 20-4 revealed TRU activity greater than 160 pCi/g at one additional location, NW 19-5, so the sampling was extended around that location. A third TRU value greater than 160 pCi/g was found in the additional samples. The investigation was terminated at this point because no 0.0625 hectare centered on either NW 20-4 or NW 19-5 had average TRU activity greater than 160 pCi/g. In addition, the one-hectare area centered on NW 20-4 was thoroughly sampled (186 samples at 40 locations), yet only three of those samples had TRU activity exceeding 160 pCi/g. At 33 of the 40 locations, the highest TRU value was near the surface - 20 cm or shallower. The average over the layer with highest activity, including all three high TRU values, was less than 100 pCi/g. The sampling locations around NW 20-4 and the highest TRU value at each are shown in Figure 7-71. Because no 0.0625 hectare with average TRU activity exceeding 160 pCi/g was found in these investigations, no subsurface excision was done at either location. Overall results of the FPDB characterization of Janet for 137Cs and 9%Sr are shown as isopleths on the 0-40 em profile means in Figures 7-72 to 7-79. The isopleths are shown separately for the four quadrants of Janet for added clarity and detail. Final Characterization It was decided in April 1979, after all other cleanup activities were complete, to excise the Plow-X control plots (see Section 6.7) because no further experimental use of the area was contemplated. The soil excision and IMP resurvey were completed 10 May 1979; 720 cubic meters (940 eubie yards) of soil containing an estimated 0.05 curies of TRU activity were removed from this area. The post-cleanup isopleths on TRU activity based on final data on Janet are shown by quadrant in Figures 7-80 through 7-83. Table 7-4 summarizes the island average results for 1387Cs, 60Co and TRU activity from IMP data. The island average transuranics value reported in the Certification is 20 pCi/gm for surface soil, and the transuranics classification is Residence. 290