IMP measurements were made at 45 locations; eight were at locations originally measured on the 50 m grid and the remainder were on intermediate 25 m grid nodes. Figure 7-2 shows the additional soil and IMP sampling locations, Two of the eight repeat IMP measurements were not comparableto the original data because the soil at those locations was severely disturbed when the photo bunker was demolished and removed. The other six repeat measurements were used to compute an additional correction factor of 1.72 + 0.18 (see Tech Note 5.1). This correction resolved most, but not all, of the remaining discrepancy between soil and IMP data. In July 1978 it was discovered that detector SN:496 had suffered a step-function loss of efficiency during the period 17-21 March 1978 as a result of mechanical damage. The measurements on Alice had been done after the damage, so an additional detector effective area correction factor of 1.16 should have been applied (see Tech Note 5.2). The computed voltage correction would then have been 2.00 instead of 1.72. The final characterization of Alice for surface TRU activity included both voltage corrections, the efficiency correction, and was based on final IMP data (see Tech Note 23 for discussion of original versus final data). Fission Product Sampling and Subsurface Investigations Alice was sampled on a 50 m grid for the Fission Product Data Base Program (FPDB) in support of the dose assessment (see Section 6.11). Samples were taken at 26 locations and soil from seven of these was analyzed for 90sr. Tables 7-1, 7-2 and 7-3 summarize the results for 0-15 em data for 137Cs, 99Sr, and 239,440 py, respectively. Two locations, 4-BL-0 and 14-S-4, each had one subsurface sample with TRU activity in excess of 160 pCi/g. The two locations were investigated using the method described in Tech Note 18. No further evidence of subsurface contamination was found, as shown by the results in Figures 7-4 and 7-5. It was concluded that the two elevated subsurface observations resulted from surface soil being disturbed and mixed during lane-cutting and debris-removal activities. Final Characterization Figure 7-3 shows isopleths on the surface TRU activity on Alice, based on final data, including all voltage and efficiency corrections. Island averages for TRU, 13705 and 59Co are given in Table 7-5. The island average transuranies value reported in the Certification is 76 pCi/gm for surface soil, and the transuranies classification is Food Gathering. 20 18 ! 16 i4 12 ig | | a | & | 4 2 Q Ne—— OCEAN “ N BL lo~ /(O ) s$2—— / sa 56— ( ) —_ ~Sf a aNLPPROXIVATE HIGH TIDE LINE, iS72 LAGOON ALICE - BOKOLUO re 50m FIGURE 7-3. ISOPLETHS ON FINAL ESTIMATED SURFACE TRU ACTIVITY IN pCi/g FOR ISLAND ALICE 213