Mr. Tom McCraw September 22, 1976 Page 7. is not necessary when it really is necessary) is the most crucial for certification purposes. Sampling for certification should also be done independently for homogeneous areas within islands. TABLE 2 Number of Samples* Required to be 100(1-8)% Sure that the True Proportion of Samples With Concentrations Greater Than.L is Less Than Po B .01 .05 .10 .20 .01 458 298 229 160 Po .05 90 58 45 31 .10 44 29 22 16 “Based on assumption that we will find no samples with activities greater than L. Question 5: ——~—~—~ For cleanup operations, is there some optimum combination of In-Situ, soi] sampling, and wet chemistry measurements that yields the most relevant information to guide con- taminated soil removal at the Teast cost? Can a generalized approach be developed for use with all islands or should guidance be derived for the known conditions on each island requiring change? The question of optimum combination of In-Situ and soil sampling needs to be addressed relative to the kriging procedure. Hence, Dr. Delfiner should be consulted on this matter. In general the optimum combination will depend in part on how wel] the In-Situ and plutonium concentrations from soil samples are correlated; and on the relative costs of the two procedures. Gilbert and Eberhardt (1976, "An Evaluation of Double Sampling for Estimating Plutonium Inventory in Soil", Radioecology and Energy Resources, Proceedings of the Fourth- National Symposium on Radioecology, Dowden, Hutchinson and Ross, Inc.) discuss the issues involved.