DOE received several different estimates of the total volume of soil removed from Kickapoo. The results for each of these estimates using mixed linear and exponential assumptions are: Volume Distribution Areas with Estimate of Total Volume Estimate Subsurface Total Volume Contamination Areas without Total Contamination Removed Subsurface cu. yd. cu. yd. Activity Ci 7 July 78, J3 22 July 78, B Co 84th Engr 4000 1175 2825 0.45 4400 1290 3110 0.50 sample sheets 4500 1320 3180 0.51 22 July 78, FRST-truck In order to check how much effect the models chosen have on the estimates of total activity removed, the estimates were repeated assuming only linear gradients. That is, the average for areas without subsurface contamination was computed as 0.5(131 + 31.8) = 81.4 pCi/g TRU. In areas with subsurface contamination, the assumption was that the gradient was linear with a positive slope of 20 em and linear with a negative slope below 20 em. The average concentration would then be 0.4 [0.5(203 + 194)]+ 0.6 [0.5(194 + 85.4)] = 0.4 (198.5) + 0.6 (139.7) = 163.2 pCi/g TRU. The computed activity removed for the various volume estimates under the all-linear assumptionis: Estimated Total Activity Total Volume Removed 4000 cu. yds. 4400 cu. yds. 4500 cu. yds. 0.50 Ci 0.55 Ci 0.56 Ci The differences between the models are far less than the difference between the two methods (IMP versus truck samples). The IMP methodis preferable for a number of reasons: 1, 2. 3. 4. 5. The truck samples are biased high. Truck volumes are difficult to estimate accurately, and are not likely to be consistent. IMP readings average over a large area, thus taking a larger sample of the population. IMP readings are unbiased and have much lower variance than soil samples. Total activity computations are fairly insensitive to errors in fitting a function to the soil gradient. Therefore, the values derived by the mixed linear and exponential models are to be considered the most reliable, and the IMP sampling data is preferable for future computations of total activity removed. (Editor's Note: Following thorough reappraisal of various measurement parameters (ef. Tech Note 23) the final estimates of TRU activity in soil removed from Island Sally are: Yuma 0.28 Ci; Hustead, 0.16 Ci; Aomon Crypt, 0.93 Ci; Island Total, 2.22 Ci). B~-10-4 Kickapoo, 0.85 Ci; shen Date & Source of