$B8— O OO) © O) a & = BENCHMARK: WELL RILEY (= IMP LOCATION x = SOIL SAMPLE LOCATION BELLE - BOKOMBAKO 4 s2— A APPROXIMATE HIGH TIDE LINE, i972 bb a OQ ao Zz se OO & © O) © O) O O 0 $4— - S2-— is > O BL— oe O OO) OY © d) © - N2— no ~5Onmn FIGURE 7-6. COASTLINE AND DATA COLLECTION LOCATIONS FOR ISLAND BELLE Fission Product Sampling and Subsurface Investigations Belle was sampled on a 50 m grid for the Fission Product Data Base (FPDB) sampling program in support of the dose assessment (See Section 6.11). There were 40 sampling locations, and soil from 11 of these was analyzed for 9%Sr. Tables 7-1, 7-2 and 7-3 summarize the results for 0-15 em data on 137Cs, 90S- and 239,24 Pu, respectively. Analysis of the FPDB samples showed that eight locations had subsurface TRU activity exceeding 160 pCi/g. All eight locations, 0-BL-0, 2-N-2, 6-N-2, 8-N-2, 12-BL-0, 14-S-2, 16-S-6, and 16-5-8, were investigated in July 1979 using the method described in Tech Note 18. As shown by Figures 7-7 and 7-8 respectively, no further evidence of elevated subsurface activity was found at 0-BL-0 or 2-N-2. At all of the other locations several iterations of sampling were done, including one set that was inadvertently taken at the wrong distance at locations 14-S-2, 16-S-6, and 16-S-8. Other than the original FPDB samples which exceeded 160 pCi/g, no sample deeper than the 0-5 em interval had TRU activity exceeding 160 pCi/g. This result led to the conclusion that the elevated subsurface activity in the FPDB samples resulted from surface soil having been mixed and turned under. the subsequent samples were taken in undisturbed areas.) (All Many of the 0-5 ecm samples had TRU activity greater than 160 pCi/g but none of the 5-10 em or deeper samples did (other than the original FPDB samples). It was therefore not obvious whether there might be some 0.0625 ha with TRU activity exceeding 160 pCi/g in the 2.5 - 7.5 em layer, which was considered to be the shallowest subsurface 5 cm increment. The method described in 217