SOIL PROFILE SAMPLING SURFACE 05 TRU FPDB | 0-5 5-10 10-15 17,.6-22.5 | 15-25 i P 37.5-42.5 57.5-62.5 25-40 | a p - T | 0 E P H F a S oO — 77 .5-82.5 40-60 I a . a (CM) 97.5-102.5 117.5-122.5 bee er FIGURE 6-23. COMPARISON OF TRU AND FISSION PRODUCT SOIL PROFILE SAMPLING PLANS one-sixteenth hectare, which required data on a 6.25-m grid. The latter requirement stemmed from a policy decision that at least four values were needed to obtain an average; each value from a 6.25-m grid would represent one sixty-fourth hectare and any four adjacent points would be averaged to obtain the one-sixteenth heetare value. The iterative sampling procedure that was developed greatly reduced the number of samples which had to be collected and analyzed, and "zeroed-in" on excision boundaries (Figure 6-24) with few iterations. (Details of the procedure appear in Appendix B, Tech Note 18.) Use of the IMP detector system for sample scanning contributed separately to both the reduced number of samples requiring laboratory processing and shorter lag time in obtaining guidance for additional iterations of sampling. However, the utility of the iterative procedure is not dependent upon a "field-operative" system like the IMP. 192